Sample records for friction reduction ii

  1. Efficiency Improvement through Reduction in Friction and Wear...

    Broader source: Energy.gov (indexed) [DOE]

    killian.pdf More Documents & Publications Heavy Truck Friction & Wear Reduction Technologies Development of High Power Density Driveline for Vehicles Low-Friction Engineered...

  2. Engine Friction Reduction Through Surface Finish and Coatings...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Coatings Opportunities exist for friction reduction in piston rings and valve trains using durable, advanced material technologies, such as diamond-like carbon (DLC)...

  3. Friction Stir Spot Welding of Advanced High Strength Steels II...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    II Friction Stir Spot Welding of Advanced High Strength Steels II 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation...

  4. Friction Reduction for Microhole CT Drilling

    SciTech Connect (OSTI)

    Ken Newman; Patrick Kelleher; Edward Smalley

    2007-03-31T23:59:59.000Z

    The objective of this 24 month project focused on improving microhole coiled tubing drilling bottom hole assembly (BHA) reliability and performance, while reducing the drilling cost and complexity associated with inclined/horizontal well sections. This was to be accomplished by eliminating the need for a downhole drilling tractor or other downhole coiled tubing (CT) friction mitigation techniques when drilling long (>2,000 ft.) of inclined/horizontal wellbore. The technical solution to be developed and evaluated in this project was based on vibrating the coiled tubing at surface to reduce the friction along the length of the downhole CT drillstring. The Phase 1 objective of this project centered on determining the optimum surface-applied vibration system design for downhole CT friction mitigation. Design of the system would be based on numerical modeling and laboratory testing of the CT friction mitigation achieved with various types of surface-applied vibration. A numerical model was developed to predict how far downhole the surface-applied vibration would travel. A vibration test fixture, simulating microhole CT drilling in a horizontal wellbore, was constructed and used to refine and validate the numerical model. Numerous tests, with varying surface-applied vibration parameters were evaluated in the vibration test fixture. The data indicated that as long as the axial force on the CT was less than the helical buckling load, axial vibration of the CT was effective at mitigating friction. However, surface-applied vibration only provided a small amount of friction mitigation as the helical buckling load on the CT was reached or exceeded. Since it would be impractical to assume that routine field operations be conducted at less than the helical buckling load of the CT, it was determined that this technical approach did not warrant the additional cost and maintenance issues that would be associated with the surface vibration equipment. As such, the project was concluded following completion of Phase 1, and Phase 2 (design, fabrication, and testing of a prototype surface vibration system) was not pursued.

  5. Some Hamiltonian models of friction II

    SciTech Connect (OSTI)

    Egli, Daniel; Gang Zhou [Institute for Theoretical Physics, ETH Zurich, CH-8093 Zuerich (Switzerland)

    2012-10-15T23:59:59.000Z

    In the present paper we consider the motion of a very heavy tracer particle in a medium of a very dense, non-interacting Bose gas. We prove that, in a certain mean-field limit, the tracer particle will be decelerated and come to rest somewhere in the medium. Friction is caused by emission of Cerenkov radiation of gapless modes into the gas. Mathematically, a system of semilinear integro-differential equations, introduced in Froehlich et al. ['Some hamiltonian models of friction,' J. Math. Phys. 52(8), 083508 (2011)], describing a tracer particle in a dispersive medium is investigated, and decay properties of the solution are proven. This work is an extension of Froehlich et al. ['Friction in a model of hamiltonian dynamics,' Commun. Math. Phys. 315(2), 401-444 (2012)]; it is an extension because no weak coupling limit for the interaction between tracer particle and medium is assumed. The technical methods used are dispersive estimates and a contraction principle.

  6. Some Hamiltonian Models of Friction II

    E-Print Network [OSTI]

    Daniel Egli; Gang Zhou

    2011-08-29T23:59:59.000Z

    In the present paper we consider the motion of a very heavy tracer particle in a medium of a very dense, non-interacting Bose gas. We prove that, in a certain mean-field limit, the tracer particle will be decelerated and come to rest somewhere in the medium. Friction is caused by emission of Cerenkov radiation of gapless modes into the gas. Mathematically, a system of semilinear integro-differential equations, introduced in [FSSG10], describing a tracer particle in a dispersive medium is investigated, and decay properties of the solution are proven. This work is an extension of [FGS10]; it is an extension because no weak coupling limit for the interaction between tracer particle and medium is assumed. The technical methods used are dispersive estimates and a contraction principle.

  7. TEXTURE-INDUCED CAVITATION BUBBLES AND FRICTION REDUCTION IN THE ELROD-ADAMS MODEL

    E-Print Network [OSTI]

    Buscaglia, Gustavo C.

    TEXTURE-INDUCED CAVITATION BUBBLES AND FRICTION REDUCTION IN THE ELROD-ADAMS MODEL Hugo M. Checoa, Friction reduction, Cavitation, Numerical simulation. Symbol Description a, b the pad occupies the region of textures µ dynamic viscosity cavitation boundary 0 cavitated region + pressurized region 1 INTRODUCTION

  8. Vehicle Technologies Office Merit Review 2014: Engine Friction Reduction Technologies

    Broader source: Energy.gov [DOE]

    Presentation given by Argonne National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about engine friction...

  9. Bar-Halo Friction in Galaxies II: Metastability

    E-Print Network [OSTI]

    J. A. Sellwood; Victor P. Debattista

    2005-11-05T23:59:59.000Z

    It is well-established that strong bars rotating in dense halos generally slow down as they lose angular momentum to the halo through dynamical friction. Angular momentum exchanges between the bar and halo particles take place at resonances. While some particles gain and others lose, friction arises when there is an excess of gainers over losers. This imbalance results from the generally decreasing numbers of particles with increasing angular momentum, and friction can therefore be avoided if there is no gradient in the density of particles across the major resonances. Here we show that anomalously weak friction can occur for this reason if the pattern speed of the bar fluctuates upwards. After such an event, the density of resonant halo particles has a local inflexion created by the earlier exchanges, and bar slowdown can be delayed for a long period; we describe this as a metastable state. We show that this behavior in purely collisionless N-body simulations is far more likely to occur in methods with adaptive resolution. We also show that the phenomenon could arise in nature, since bar-driven gas inflow could easily raise the bar pattern speed enough to reach the metastable state. Finally, we demonstrate that mild external, or internal, perturbations quickly restore the usual frictional drag, and it is unlikely therefore that a strong bar in a galaxy having a dense halo could rotate for a long period without friction.

  10. Department of Mechanical and Nuclear Engineering Spring 2012 Heavy-Duty Diesel Engine Friction Reduction Testing and Analysis

    E-Print Network [OSTI]

    Demirel, Melik C.

    PENNSTATE Department of Mechanical and Nuclear Engineering Spring 2012 Heavy-Duty Diesel Engine Friction Reduction Testing and Analysis Overview Volvo Group Powertrain Engineering is interested will need to be constructed that can motor the engine and measure power losses using a torque sensor built

  11. Efficiency Improvement through Reduction in Friction and Wear in Powertrain Systems

    SciTech Connect (OSTI)

    Michael Killian

    2009-09-30T23:59:59.000Z

    The objective of this project is to improve the efficiency of truck drivelines through reduction of friction and parasitic losses in transmission and drive axles. Known efficiencies for these products exceeded 97 percent, so the task was not trivial. The project relied on a working relationship between modeling and hardware testing. Modeling was to shorten the development cycle by guiding the selection of materials, processes and strategies. Bench top and fixture tests were to validate the models. Modeling was performed at a world class, high academic level, but in the end, modeling did not impact the hardware development as much as intended. Insights leading to the most significant accomplishments came from bench top and fixture tests and full scale dynamometer tests. A key development in the project was the formulation of the implementation strategy. Five technical elements with potential to minimize friction and parasitic losses were identified. These elements included churning, lubrication, surface roughness, coatings and textures. An interesting fact is that both Caterpillar and Eaton independently converged on the same set of technical elements in formulating their implementation strategies. Exploiting technical elements of the implementation strategy had a positive impact on transmission and drive axle efficiencies. During one dynamometer test of an Eaton Best Tech 1 transmission, all three gear ranges tested: Under drive, direct drive and over drive, showed efficiencies greater than 99 percent. Technology boosts to efficiency for transmissions reached 1 percent, while efficiency improvements to drive axle pushed 2 percent. These advancements seem small, but the accomplishment is large considering that these products normally run at greater than 97 percent efficiency. Barriers and risks to implementing these technology elements are clear. Schemes using a low fill sump and spray tubes endanger the gears and bearings by lubricant starvation. Gear coatings have exhibited durability issues, stripping away under conditions less demanding than 750,000 miles in service on the road. Failed coatings compound the problem by contaminating the lubricant with hard particles. Under the most severe conditions, super finished surfaces may polish further, reaching a surface roughness unable to support the critical oil film thickness. Low viscosity and low friction lubricants may not protect the gears and bearings adequately leading to excessive pitting, wear and noise. Additives in low friction oils may not stay in solution or suspended thus settling to the bottom and unavailable when they are needed most. Technical barriers and risks can be overcome through engineering, but two barriers remain formidable: (1) cost of the technology and (2) convincing fleet owners that the technology provides a tangible benefit. Dry sumps lower lubricant operating temperatures so the removal of heat exchangers and hoses and reduced demand on engine cooling systems justify their use. The benefits of surface texturing are varied and remain unproven. Lubricant costs seem manageable, but the cost of super finishing and gear coating are high. These are issues of scale and processing technology. Going across the board with gear super finishing and coating will reduce costs. Pushing the envelope to applications with higher torque and higher power density should drive the adoption of these technologies. Fleet owners are an educated and seasoned lot. Only technology measureable in dollars returned is used on truck fleets. To convince fleet owners of the benefit of these technologies, new precision in measuring fuel efficiency must be introduced. Legislation for a minimum standard in truck miles per gallon would also enable the use of these technologies. Improving the efficiency of truck transmissions and axle will make a noticeable impact on the fuel consumption by heavy vehicles in the United States. However, the greatest benefit will come when all the individual efficiency technologies like hybrid power, aerodynamic fairings, auxiliary power units, super

  12. Department of Mechanical Engineering Fall 2011 Heavy Duty Diesel Engine Friction Reduction

    E-Print Network [OSTI]

    Demirel, Melik C.

    PENNSTATE Department of Mechanical Engineering Fall 2011 Heavy Duty Diesel Engine Friction the friction losses of a heavy duty diesel engine. In addition, a tear down procedure needed to be created needs Discussed test cell configuration with Diesel Combustion & Emissions Laboratory Performed

  13. In situ control of lubricant properties for reduction of power cylinder friction through thermal barrier coating

    E-Print Network [OSTI]

    Molewyk, Mark Allen

    2014-01-01T23:59:59.000Z

    Lowering lubricant viscosity to reduce friction generally carries a side effect of increased metal-metal contact in mixed or boundary lubrication, for example near top ring reversal along the engine cylinder liner. A ...

  14. Skin friction blistering: computer model.

    E-Print Network [OSTI]

    Xing, Malcolm; Pan, Ning; Zhong, Wen; Maibach, Howard

    2007-01-01T23:59:59.000Z

    K. L.Jones, B. H. , Friction blisters. Pathophysiology,and M.B. Sulzberger, The friction blister. Mil Med, 1972.on blisters produced by friction. II. The blister fluid. J

  15. Overview of Friction and Wear Reduction for Heavy Vehicles | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankCombustion | Department ofT ib l L d F SSales LLCDiesel Enginesthewith2009Energy Friction and Wear

  16. Vehicle Technologies Office Merit Review 2014: Friction Reduction through Surface Modification (Agreement ID:23284) Project ID:18518

    Broader source: Energy.gov [DOE]

    Presentation given by Oak Ridge National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about friction...

  17. Department of Energy and Electrical Engineering Spring 2012 Heavy-Duty Diesel Engine Friction Reduction Testing and Analysis

    E-Print Network [OSTI]

    Demirel, Melik C.

    PENNSTATE Department of Energy and Electrical Engineering Spring 2012 Heavy-Duty Diesel Engine and pumping frictional losses on Volvo-Mack's 11 liter Diesel Engine. Thermocouples and pressure transducers is to quantify friction losses on Volvo's current 11-liter engine model. Team members will remove hardware

  18. Casimir Friction Force and Energy Dissipation for Moving Harmonic Oscillators. II

    E-Print Network [OSTI]

    Johan S. Høye; I. Brevik

    2010-09-16T23:59:59.000Z

    This paper is a second in a series devoted to the study of a two-oscillator system in linear relative motion (the first one published as a letter in Europhys. Lett. 91, 60003 (2010)). The main idea behind considering this kind of system is to use it as a simple model for Casimir friction. In the present paper we extend our previous theory so as to obtain the change in the oscillator energy to second order in the perturbation, even though we employ first order perturbation theory only. The results agree with, and confirm, our earlier results obtained via different routes. The friction force is finite at finite temperatures, whereas in the case of two oscillators moving with constant relative velocity the force becomes zero at zero temperature, due to slowly varying coupling.

  19. ALTERNATE REDUCTANT COLD CAP EVALUATION FURNACE PHASE II TESTING

    SciTech Connect (OSTI)

    Johnson, F.; Stone, M.; Miller, D.

    2014-09-03T23:59:59.000Z

    Savannah River Remediation (SRR) conducted a Systems Engineering Evaluation (SEE) to determine the optimum alternate reductant flowsheet for the Defense Waste Processing Facility (DWPF). Specifically, two proposed flowsheets (nitric–formic–glycolic and nitric–formic–sugar) were evaluated based upon results from preliminary testing. Comparison of the two flowsheets among evaluation criteria indicated a preference towards the nitric–formic–glycolic flowsheet. Further research and development of this flowsheet eliminated the formic acid, and as a result, the nitric–glycolic flowsheet was recommended for further testing. Based on the development of a roadmap for the nitric–glycolic acid flowsheet, Waste Solidification Engineering (WS-E) issued a Technical Task Request (TTR) to address flammability issues that may impact the implementation of this flowsheet. Melter testing was requested in order to define the DWPF flammability envelope for the nitric-glycolic acid flowsheet. The Savannah River National Laboratory (SRNL) Cold Cap Evaluation Furnace (CEF), a 1/12th scale DWPF melter, was selected by the SRR Alternate Reductant project team as the melter platform for this testing. The overall scope was divided into the following sub-tasks as discussed in the Task Technical and Quality Assurance Plan (TTQAP): ? Phase I - A nitric–formic acid flowsheet melter test (unbubbled) to baseline the CEF cold cap and vapor space data to the benchmark melter flammability models; ? Phase II - A nitric–glycolic acid flowsheet melter test (unbubbled and bubbled) to: o Define new cold cap reactions and global kinetic parameters in support of the melter flammability model development; o Quantify off-gas surging potential of the feed; o Characterize off-gas condensate for complete organic and inorganic carbon species. After charging the CEF with cullet from Phase I CEF testing, the melter was slurry-fed with glycolic flowsheet based SB6-Frit 418 melter feed at 36% waste loading and was operated continuously for 25 days. Process data was collected throughout testing and included melter operation parameters and off-gas chemistry. In order to generate off-gas data in support of the flammability model development for the nitric-glycolic flowsheet, vapor space steady state testing in the range of ~300-750°C was conducted under the following conditions, (i) 100% (nominal and excess antifoam levels) and 125% stoichiometry feed and (ii) with and without argon bubbling. Adjustments to feed rate, heater outputs and purge air flow were necessary in order to achieve vapor space temperatures in this range. Surge testing was also completed under nominal conditions for four days with argon bubbling and one day without argon bubbling.

  20. Ni(II) Salts and 2-Propanol Effect Catalytic Reductive Coupling of Epoxides and Alkynes

    E-Print Network [OSTI]

    Beaver, Matthew G.

    A Ni-catalyzed reductive coupling of alkynes and epoxides using Ni(II) salts and simple alcohol reducing agents is described. Whereas previously reported conditions relied on Ni(cod)2 and Et3B, this system has several ...

  1. Abiotic U(VI) Reduction by Sorbed Fe(II) on Natural Sediments

    SciTech Connect (OSTI)

    Fox, Patricia M.; Davis, James A.; Kukkadapu, Ravi K.; Singer, David M.; Bargar, John R.; Williams, Kenneth H.

    2013-09-15T23:59:59.000Z

    Laboratory experiments were performed as a function of aqueous Fe(II) concentration to determine the uptake and oxidation of Fe(II), and Fe(II)-mediated abiotic reduction of U(VI) by aquifer sediments from the Rifle IFRC field site in Colorado, USA. Mössbauer analysis of the sediments spiked with aqueous 57Fe(II) showed that 57Fe(II) was oxidized on the mineral surfaces to 57Fe(III) and most likely formed a nano-particulate Fe(III)-oxide or ferrihydrite-like phase. The extent of 57Fe oxidation decreased with increasing 57Fe(II) uptake, such that 100 % was oxidized at 7.3 ?mol/g Fe and 52 % at 39.6 ?mol/g Fe, indicating that the sediments had a finite capacity for oxidation of Fe(II). Abiotic U(VI) reduction was observed by XANES spectroscopy only when the Fe(II) uptake was greater than approximately 20 ?mol/g and surface-bound Fe(II) was present. The level of U(VI) reduction increased with increasing Fe(II)- loading above this level to a maximum of 18 and 36 % U(IV) at pH 7.2 (40.7 ?mol/g Fe) and 8.3 (56.1 ?mol/g Fe), respectively in the presence of 400 ppm CO2. Greater U(VI) reduction was observed in CO2 free systems [up to 44 and 54 % at pH 7.2 (17.3 ?mol/g Fe) and 8.3 (54.8 ?mol/g Fe), respectively] compared to 400 ppm CO2 systems, presumably due to differences in aqueous U(VI) speciation. While pH affects the amount of Fe(II) uptake onto the solid phase, with greater Fe(II) uptake at higher pH, similar amounts of U(VI) reduction were observed at pH 7.2 and 8.3 for a similar Fe(II) uptake. Thus, it appears that abiotic U(VI) reduction is controlled primarily by Fe(II) concentration and aqueous U(VI) speciation. The range of Fe(II) loadings tested in this study are within the range observed in bioreduced sediments, suggesting that Fe(II)-mediated abiotic U(VI) reduction may indeed play a role in field settings.

  2. CU(II): catalyzed hydrazine reduction of ferric nitrate

    SciTech Connect (OSTI)

    Karraker, D.G.

    1981-11-01T23:59:59.000Z

    A method is described for producing ferrous nitrate solutions by the cupric ion-catalyzed reduction of ferric nitrate with hydrazine. The reaction is complete in about 1.5 hours at 40/sup 0/C. Hydrazoic acid is also produced in substantial quantities as a reaction byproduct.

  3. Rate of reduction of ore-carbon composites: Part II. Modeling of reduction in extended composites

    SciTech Connect (OSTI)

    Fortini, O.M.; Fruehan, R.J. [US Steel Research & Technological Center, Monroeville, PA (United States)

    2005-12-01T23:59:59.000Z

    A new process for ironmaking was proposed using a rotary hearth furnace and an iron bath smelter to produce iron employing wood charcoal as an energy source and reductant. This paper examines reactions in composite pellet samples with sizes close to sizes used in industrial practice (10 to 16 min in diameter). A model was constructed using the combined kinetic mechanism developed in Part I of this series of articles along with equations for the computation of pellet temperature and shrinkage during the reaction. The analysis of reaction rates measured for pellets with wood charcoal showed that heat transfer plays a significant role in their overall rate of reaction at elevated temperatures. The slower rates measured in pellets containing coal char show that the intrinsic kinetics of carbon oxidation is more significant than heat transfer. Model calculations suggest that the rates are highly sensitive to the thermal conductivity of pellets containing wood charcoal and are less sensitive to the external conditions of heat transfer. It was seen that the changes in pellet surface area and diameter due to shrinkage introduce little change on reaction rates. The model developed provides an adequate description of pellets of wood charcoal up to circa 90% of reduction. Experimentally determined rates of reduction of iron oxide by wood charcoal were approximately 5 to 10 times faster than rates measured in pellets with coal char.

  4. Friction Induced Skin Tags

    E-Print Network [OSTI]

    Allegue, Francisco; Fachal, Carmen; Pérez-Pérez, Lidia

    2008-01-01T23:59:59.000Z

    Duplantis KL, Jones BH. Friction blisters. Pathophysiology,Friction Induced Skin Tags Francisco Allegue MD 1 , Carmenetiopathogenic role for friction. Introduction Skin tags (

  5. REDUCED ENGINE FRICTION AND WEAR

    SciTech Connect (OSTI)

    Ron Matthews

    2005-05-01T23:59:59.000Z

    This Final Technical Report discusses the progress was made on the experimental and numerical tasks over the duration of this project regarding a new technique for decreasing engine friction and wear via liner rotation. The experimental subtasks involved quantifying the reduction in engine friction for a prototype rotating liner engine relative to a comparable baseline engine. Both engine were single cylinder conversions of nominally identical production four-cylinder engines. Hot motoring tests were conducted initially and revealed that liner rotation decreased engine friction by 20% under motoring conditions. A well-established model was used to estimate that liner rotation should decrease the friction of a four-cylinder engine by 40% under hot motoring conditions. Hot motoring tear-down tests revealed that the crankshaft and valve train frictional losses were essentially the same for the two engines, as expected. However, the rotating liner engine had much lower (>70%) piston assembly friction compared to the conventional engine. Finally, we used the Instantaneous IMEP method to compare the crank-angle resolved piston assembly friction for the two engines. Under hot motoring conditions, these measurements revealed a significant reduction in piston assembly friction, especially in the vicinity of compression TDC when the lubrication regime transitions from hydrodynamic through mixed and into boundary friction. We have some remaining problems with these measurements that we expect to solve during the next few weeks. We will then perform these measurements under firing conditions. We also proposed to improve the state-of-the-art of numerical modeling of piston assembly friction for conventional engines and then to extend this model to rotating liner engines. Our research team first modeled a single ring in the Purdue ring-liner test rig. Our model showed good agreement with the test rig data for a range of speeds and loads. We then modeled a complete piston assembly in an engine. The model appears to produce the correct behavior, but we cannot quantify its strengths or weaknesses until our crank-angle-resolved measurements have been completed. Finally, we proposed and implemented a model for the effects of liner rotation on piston assembly friction. Here, we propose that the rotating liner design is analogous to the shaft-bushing mechanism. Therefore, we used the side-slip rolling friction model to simulate the effects of liner rotation. This model appears to be promising, but final analysis of its strengths and/or weaknesses must await our crank-angle-resolved measurements.

  6. Introduction Rolling and Friction

    E-Print Network [OSTI]

    Kuhn, Matthew R.

    Introduction Kinematics Solutions Rolling and Friction in Discrete Element Simulations Matthew R of rolling resistance Creep-friction definition Creep-friction vs. Cattaneo-Mindlin friction Classification / papers / EMI2011.pdf #12;Introduction Kinematics Solutions Classification of rolling resistance Creep-friction

  7. Solid friction in gel electrophoresis S. F. Burlatskya)

    E-Print Network [OSTI]

    Deutch, John

    Solid friction in gel electrophoresis S. F. Burlatskya) and John M. Deutch Department of Chemistry 1995 We study the influence of solid frictional forces acting on polymer chains moving in a random environment. We show that the total reduction in the chain tension resulting from the small friction between

  8. Quantum friction

    E-Print Network [OSTI]

    R. Tsekov

    2012-03-12T23:59:59.000Z

    The Brownian motion of a light quantum particle in a heavy classical gas is theoretically described and a new expression for the friction coefficient is obtained for arbitrary temperature. At zero temperature it equals to the de Broglie momentum of the mean free path divided by the mean free path. Alternatively, the corresponding mobility of the quantum particle in the classical gas is equal to the square of the mean free path divided by the Planck constant. The Brownian motion of a quantum particle in a quantum environment is also discussed.

  9. Friction in (im-)miscible polymer brush systems and the role of transverse polymer-tilting

    E-Print Network [OSTI]

    Mueser, Martin

    Friction in (im-)miscible polymer brush systems and the role of transverse polymer-tilting Sissi de preferred solvent, leading to low friction and low wear rates. Here, we demonstrate, using molecular systems also show smaller friction than miscible systems, although the friction reduction is less than

  10. Reduction

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared at 278, 298,NIST 800-53 National Renewable EnergyReducingReduction

  11. Biological Oxidation of Fe(II) in Reduced Nontronite Coupled with Nitrate Reduction by Pseudogulbenkiania sp. Strain 2002

    SciTech Connect (OSTI)

    Zhao, Linduo; Dong, Hailiang; Kukkadapu, Ravi K.; Agrawal, A.; Liu, Deng; Zhang, Jing; Edelmann, Richard E.

    2013-10-15T23:59:59.000Z

    Nitrate contamination in soils, sediments, and water bodies is a significant issue. Although much is known about nitrate degradation in these environments, especially via microbial pathways, a complete understanding of all degradation processes, especially in clay mineral-rich soils, is still lacking. The objective of this study was to study the potential of removing nitrate contaminant using structural Fe(II) in clay mineral nontronite. Specifically, the coupled processes of microbial oxidation of Fe(II) in microbially reduced nontronite (NAu-2) and nitrate reduction by Pseudogulbenkiania species strain 2002 was investigated. Bio-oxidation experiments were conducted in bicarbonate-buffered medium under both growth and nongrowth conditions. The extents of Fe(II) oxidation and nitrate reduction were measured by wet chemical methods. X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and 57Fe-Mössbauer spectroscopy were used to observe mineralogical changes associated with Fe(III) reduction and Fe(II) oxidation in nontronite. The bio-oxidation extent under growth and nongrowth conditions reached 93% and 57%, respectively. Over the same time period, nitrate was completely reduced under both conditions to nitrogen gas (N2), via an intermediate product nitrite. Magnetite was a mineral product of nitrate-dependent Fe(II) oxidation, as evidenced by XRD data and TEM diffraction patterns. The results of this study highlight the importance of iron-bearing clay minerals in the global nitrogen cycle with potential applications in nitrate removal in soils.

  12. Rotating Liner Engine: Improving Efficiency of Heavy Duty Diesels by Significant Friction Reduction, and Extending the Life of Heavy Duty Engines.

    SciTech Connect (OSTI)

    Dardalis, Dimitrios

    2013-12-31T23:59:59.000Z

    This report describes the work on converting a 4 cylinder Cummins ISB engine into a single cylinder Rotating Liner Engine functioning prototype that can be used to measure the friction benefits of rotating the cylinder liner in a high pressure compression ignition engine. A similar baseline engine was also prepared, and preliminary testing was done. Even though the fabrication of the single cylinder prototype was behind schedule due to machine shop delays, the fundamental soundness of the design elements are proven, and the engine has successfully functioned. However, the testing approach of the two engines, as envisioned by the original proposal, proved impossible due to torsional vibration resonance caused by the single active piston. A new approach for proper testing has been proposed,

  13. Friction between Ring Polymer Brushes

    E-Print Network [OSTI]

    A. Erbas; J. Paturej

    2015-01-07T23:59:59.000Z

    Friction between ring-polymer brushes at melt densities sliding past each other are studied using extensive course-grained molecular dynamics simulations and scaling arguments, and the results are compared to the friction between linear-polymer brushes. We show that for a velocity range spanning over three decades, the frictional forces measured for ring-polymer brushes are half the corresponding friction in case of linear brushes. In the linear-force regime, the weak inter-digitation of two ring brushes compared to linear brushes also leads to a lower number of binary collisions between the monomers of opposing brushes. At high velocities, where the thickness of the inter-digitation layer between two opposing brushes is on the order monomer size regardless of brush topology, stretched segments of ring polymers take a double-stranded conformation. As a result, monomers of the double-stranded segments collide less with the monomers of the opposing ring brush even though a similar number of monomers occupies the inter-digitation layer for ring and linear-brush bilayers. The numerical data obtained from our simulations is consistent with the proposed scaling analysis. Conformation-dependent frictional reduction observed in ring brushes can have important consequences in non-equilibrium bulk systems.

  14. Skin friction blistering: computer model.

    E-Print Network [OSTI]

    Xing, Malcolm; Pan, Ning; Zhong, Wen; Maibach, Howard

    2007-01-01T23:59:59.000Z

    on blisters produced by friction. I. Results of linearDuplantis KL, Jones BH. Friction blisters. Pathophysiology,WA, Sulzberger MB. The friction blister. Mil Med 6. Cortese

  15. Frictional Widgets: Enhancing Touch Interfaces with Programmable Friction

    E-Print Network [OSTI]

    Levesque, Vincent

    Frictional Widgets: Enhancing Touch Interfaces with Programmable Friction Abstract Touch the design possibilities offered by augmenting touchscreens with programmable surface friction. Four exemplar of touch interactions can be enhanced when using a touchscreen with dynamically varied surface friction. We

  16. Piston ring design for reduced friction in modern internal combustion engines

    E-Print Network [OSTI]

    Smedley, Grant, 1978-

    2004-01-01T23:59:59.000Z

    Piston ring friction losses account for approximately 20% of the total mechanical losses in modern internal combustion engines. A reduction in piston ring friction would therefore result in higher efficiency, lower fuel ...

  17. Friction Tests in Magnesium Tube Hydroforming at Elevated Temperatures

    SciTech Connect (OSTI)

    Hwang, Yeong-Maw; Wang, Kuo-Hsing; Kuo, Tsung-Yu [National Sun Yat-Sen University-Department of Mechanical and Electro-mechanical Engineering, No.70, Lien-Hai Rd., Kaohsiung, Taiwan (China)

    2011-05-04T23:59:59.000Z

    In metal forming, lubricants have a variety of functions. The top priority is usually reduction of friction in order to increase the formability of the materials and reduce tool wear. Because magnesium alloys have very poor formability at room temperature, it is essential to manufacture a part from Magnesium alloys at elevated temperatures. The aim of this paper is to present a friction test method to evaluate the performance of different kinds of lubricants and determine their coefficients of friction at elevated temperatures in tube hydroforming of magnesium alloys. A self-designed experimental apparatus is used to carry out the experiments of friction tests. The coefficient of friction between the tube and die at guiding zone is determined. The effects of the internal pressure, the axial feeding velocity and temperatures on the friction forces and coefficients of friction for different lubricants are discussed.

  18. Influence of Biogenic Fe(II) on the Extent of Microbial Reduction...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    indicating that other factors, such as blockage of the electron transfer chain and mineralogy, restricted the reduction extent. This study also revealed that the relative...

  19. Rotational Quantum Friction

    E-Print Network [OSTI]

    Rongkuo Zhao; Alejandro Manjavacas; F. Javier García de Abajo; J. B. Pendry

    2012-08-21T23:59:59.000Z

    We investigate the frictional forces due to quantum fluctuations acting on a small sphere rotating near a surface. At zero temperature, we find the frictional force near a surface to be several orders of magnitude larger than that for the sphere rotating in vacuum. For metallic materials with typical conductivity, quantum friction is maximized by matching the frequency of rotation with the conductivity. Materials with poor conductivity are favored to obtain large quantum frictions. For semiconductor materials that are able to support surface plasmon polaritons, quantum friction can be further enhanced by several orders of magnitude due to the excitation of surface plasmon polaritons.

  20. Nanotribology and Nanoscale Friction

    SciTech Connect (OSTI)

    Guo, Yi [Stevens Institute of Technology, Hoboken, New Jersey; Qu, Zhihua [University of Central Florida, Orlando; Braiman, Yehuda [ORNL; Zhang, Zhenyu [ORNL; Barhen, Jacob [ORNL

    2008-01-01T23:59:59.000Z

    Tribology is the science and technology of contacting solid surfaces in relative motion, including the study of lubricants, lubrication, friction, wear, and bearings. It is estimated that friction and wear cost the U.S. economy 6% of the gross national product (Persson, 2000). For example, 5% of the total energy generated in an automobile engine is lost to frictional resistance. The study of nanoscale friction has a technological impact in reducing energy loss in machines, in microelectromechanical systems (MEMS), and in the development of durable, low-friction surfaces and ultra-thin lubrication films.

  1. LABORATORY REPORT ON THE REDUCTION AND STABILIZATION (IMMOBILIZATION) OF PERTECHNETATE TO TECHNETIUM DIOXIDE USING TIN(II)APATITE

    SciTech Connect (OSTI)

    DUNCAN JB; HAGERTY K; MOORE WP; RHODES RN; JOHNSON JM; MOORE RC

    2012-06-01T23:59:59.000Z

    This effort is part of the technetium management initiative and provides data for the handling and disposition of technetium. To that end, the objective of this effort was to challenge tin(II)apatite (Sn(II)apatite) against double-shell tank 241-AN-105 simulant spiked with pertechnetate (TcO{sub 4}{sup -}). The Sn(II)apatite used in this effort was synthesized on site using a recipe developed at and provided by Sandia National Laboratories; the synthesis provides a high quality product while requiring minimal laboratory effort. The Sn(II)apatite reduces pertechnetate from the mobile +7 oxidation state to the non-mobile +4 oxidation state. It also sequesters the technetium and does not allow for re-oxidization to the mo bile +7 state under acidic or oxygenated conditions within the tested period oftime (6 weeks). Previous work (RPP-RPT-39195, Assessment of Technetium Leachability in Cement-Stabilized Basin 43 Groundwater Brine) indicated that the Sn(II)apatite can achieve an ANSI leachability index in Cast Stone of 12.8. The technetium distribution coefficient for Sn(II)apatite exhibits a direct correlation with the pH of the contaminated media. Table A shows Sn(II)apatite distribution coefficients as a function of pH. The asterisked numbers indicate that the lower detection limit of the analytical instrument was used to calculate the distribution coefficient as the concentration of technetium left in solution was less than the detection limit. The loaded sample (200 mg of Sn(II)apatite loaded with O.311 mg of Tc-99) was subjected to different molarities of nitric acid to determine if the Sn(II)apatite would release the sequestered technetium. The acid was allowed to contact for 1 minute with gentle shaking ('1st wash'); the aqueous solution was then filtered, and the filtrate was analyzed for Tc-99. Table B shows the results ofthe nitric acid exposure. Another portion of acid was added, shaken for a minute, and filtered ('2nd wash'). The technetium-loaded Sn(II)apatite was also subjected to water leach tests. The loaded sample (0.2 g of Sn(II)apatite was loaded with 0.342 mg of Tc-99) was placed in a 200-mL distilled water column and sparged with air. Samples were taken weekly over a 6-week period, and the dissolved oxygen ranged from 8.4 to 8.7 mg/L (average 8.5 mg/L); all samples recorded less than the detection limit of 0.01 mg/L Tc-99. The mechanism by which TcO{sub 2} is sequestered and hence protected from re-oxidation appears to be an exchange with phosphate in the apatite lattice, as the phosphorus that appeared in solution after reaction with technetium was essentially the same moles of technetium that were taken up by the Sn(II)apatite (Table 6). Overall, the reduction of the mobile pertechnetate (+7) to the less mobile technetium dioxide (+4) by Sn(II)apatite and subsequent sequestration of the technetium in the material indicates that Sn(II)apatite is an excellent candidate for long-term immobilization of technetium. The indications are that the Sn(II)apatite will lend itself to sequestering and inhibiting the reoxidation to the mobile pertechnetate species, thus keeping the radionuclide out of the environment.

  2. Energy Efficiency/ Renewable Energy Impact in the Texas Emisions Reduction Plan (TERP): Volume II- Technical Report

    E-Print Network [OSTI]

    Haberl, J.; Yazdani, B.; Culp, C.; Lewis, C.; Liu, Z.; Baltazar, J. C.; Mukhopadhyay, J.; Gilman, D.; Degelman, L.; McKelvey, K.; Clardige, D.

    2011-01-01T23:59:59.000Z

    ninth annual report, Energy Efficiency/Renewable Energy (EE/RE) Impact in the Texas Emissions Reduction Plan (TERP) to the Texas Commission on Environmental Quality. The report is organized in three volumes. Volume I - Summary Report - provides...

  3. Micromachine friction test apparatus

    DOE Patents [OSTI]

    deBoer, Maarten P. (Albuquerque, NM); Redmond, James M. (Albuquerque, NM); Michalske, Terry A. (Cedar Crest, NM)

    2002-01-01T23:59:59.000Z

    A microelectromechanical (MEM) friction test apparatus is disclosed for determining static or dynamic friction in MEM devices. The friction test apparatus, formed by surface micromachining, is based on a friction pad supported at one end of a cantilevered beam, with the friction pad overlying a contact pad formed on the substrate. A first electrostatic actuator can be used to bring a lower surface of the friction pad into contact with an upper surface of the contact pad with a controlled and adjustable force of contact. A second electrostatic actuator can then be used to bend the cantilevered beam, thereby shortening its length and generating a relative motion between the two contacting surfaces. The displacement of the cantilevered beam can be measured optically and used to determine the static or dynamic friction, including frictional losses and the coefficient of friction between the surfaces. The test apparatus can also be used to assess the reliability of rubbing surfaces in MEM devices by producing and measuring wear of those surfaces. Finally, the friction test apparatus, which is small in size, can be used as an in situ process quality tool for improving the fabrication of MEM devices.

  4. Scientific uncertainties in atmospheric mercury models III: Boundary and initial conditions, model grid resolution, and Hg(II) reduction mechanism

    SciTech Connect (OSTI)

    Lin, Che-Jen [ORNL; Pongprueksa, Pruek [Lamar University; Lindberg, Steven Eric [ORNL; Jang, Carey [U.S. Environmental Protection Agency, Raleigh, North Carolina; Braverman, Thomas [U.S. Environmental Protection Agency, Raleigh, North Carolina; Bullock, Russell O [NOAA; Ho, Thomas [ORNL; Chu, Hsing-Wei [Lamar University

    2008-03-01T23:59:59.000Z

    In this study, the model response in terms of simulated mercury concentration and deposition to boundary condition (BC), initial condition (IC), model grid resolution (12 km versus 36 km), and two alternative Hg(II) reduction mechanisms, was investigated. The model response to the change of gaseous elemental mercury (GEM) concentration from 0 to 2 ngm3 in IC/BC is found to be very linear (r240.99) based on the results of sensitivity simulations in July 2001. An increase of 1 ngm3 of GEM in BC resulted in an increase of 0.81 ngm3 in the monthly average of total mercury concentration, and 1270 ngm2 in the monthly total deposition. IC has similar but weaker effects compared to those of BC. An increase of 1 ngm3 of GEM in IC resulted in an increase of 0.14 ngm3 in the monthly average of total mercury concentration, and 250 ngm2 in the monthly total deposition. Varying reactive gaseous mercury (RGM) or particulate mercury (PHg) in BC/IC has much less significant impact. Simulation results at different grid resolutions show good agreement (slope 0.950 1.026, r 0.816 0.973) in mercury concentration, dry deposition, and total deposition. The agreement in wet deposition is somewhat weaker (slope 0.770 0.794, r 0.685 0.892) due to the difference in emission dilution and simulated precipitation that subsequently change reaction rates in the aqueous phase. Replacing the aqueous Hg(II)-HO2 reduction by either RGM reduction by CO (51018cm3 molecule1 s1) or photoreduction of RGM (1105 s1) gives significantly better model agreement with the wet deposition measured by Mercury Deposition Network (MDN). Possible ranges of the reduction rates are estimated based on model sensitivity results. The kinetic estimate requires further verification by laboratory studies.

  5. Factors affecting piston ring friction

    E-Print Network [OSTI]

    Liao, Kai, Ph. D. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    The piston ring pack friction is a major contributor to the internal combustion engine mechanical friction loss. The oil control ring decides the oil supply to the top two rings in addition to being the major friction ...

  6. Friction Stir Processing for Efficient Manufacturing

    SciTech Connect (OSTI)

    Mr. Christopher B. Smith; Dr. Oyelayo Ajayi

    2012-01-31T23:59:59.000Z

    Friction at contacting surfaces in relative motion is a major source of parasitic energy loss in machine systems and manufacturing processes. Consequently, friction reduction usually translates to efficiency gain and reduction in energy consumption. Furthermore, friction at surfaces eventually leads to wear and failure of the components thereby compromising reliability and durability. In order to reduce friction and wear in tribological components, material surfaces are often hardened by a variety of methods, including conventional heat treatment, laser surface hardening, and thin-film coatings. While these surface treatments are effective when used in conjunction with lubrication to prevent failure, they are all energy intensive and could potentially add significant cost. A new concept for surface hardening of metallic materials and components is Friction Stir Processing (FSP). Compared to the current surface hardening technologies, FSP is more energy efficient has no emission or waste by products and may result in better tribological performance. FSP involves plunging a rotating tool to a predetermined depth (case layer thickness) and translating the FSP tool along the area to be processed. This action of the tool produces heating and severe plastic deformation of the processed area. For steel the temperature is high enough to cause phase transformation, ultimately forming hard martensitic phase. Indeed, FSP has been used for surface modification of several metals and alloys so as to homogenize the microstructure and refine the grain size, both of which led to improved fatigue and corrosion resistance. Based on the effect of FSP on near-surface layer material, it was expected to have beneficial effects on friction and wear performance of metallic materials. However, little or no knowledge existed on the impact of FSP concerning friction and wear performance the subject of the this project and final report. Specifically for steel, which is the most dominant tribological material, FSP can replace the current conventional surface hardening techniques used for friction and wear performance. Friction Stir Link Inc. (FSL) is teamed with Argonne National Laboratory (ANL) to develop and optimize FSP for friction and wear performance enhancement. The ultimate goal is to offer FSP and an effective alternative to some of the current energy intensive and high-cost surface hardening processes.

  7. The catalytic reduction of nitric oxide with ammonia over tetraamminecopper (II) complexes

    E-Print Network [OSTI]

    Oates, Margaret Deron

    1979-01-01T23:59:59.000Z

    primary goal has been to develop catalysts that will promote selective reduction of nitric oxide to nitrogen with various reducing agents. The use of metals and mixed metal oxide catalysts with reducing agents such as hydrogen, car- bon monoxide... the energy of the v* orbital of NO in relationship to tne energies 11, 12 of the d orbitals of the metal. ' Although nitric oxide is thermo- dynamically unstable, with respect to decomposition to nitrogen and The citations of the following cages follow...

  8. E-Print Network 3.0 - amplitudes ii systematic Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    studied. I. Introduction - Since the anomalously amplitude-dependent internal- friction peaks (i... anomalously amplitude-dependent internal-friction peak. II....

  9. Action of friction Frictional processes are not often considered in

    E-Print Network [OSTI]

    Plant, Robert

    Action of friction Frictional processes are not often considered in any detail in studies are switched off, the pressure falls to just 921mb. Frictional processes can be thought of in terms of changes. The first term on the right­hand­side represents barotropic damping by friction, and the second

  10. Static Friction Phenomena The following static friction phenomena have a direct dependency on velocity.

    E-Print Network [OSTI]

    Simpkins, Alex

    Coulomb Friction Viscous Friction Stribeck Friction Static Friction Phenomena The following static friction phenomena have a direct dependency on velocity. Static Friction Model: Friction force opposes the direction of motion when the sliding velocity is zero. Coulomb Friction Model: Friction force

  11. Friction stir welding tool

    DOE Patents [OSTI]

    Tolle, Charles R. (Idaho Falls, ID); Clark, Denis E. (Idaho Falls, ID); Barnes, Timothy A. (Ammon, ID)

    2008-04-15T23:59:59.000Z

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  12. THE PRISM MULTI-OBJECT SURVEY (PRIMUS). II. DATA REDUCTION AND REDSHIFT FITTING

    SciTech Connect (OSTI)

    Cool, Richard J. [MMT Observatory, Tucson, AZ 85721 (United States); Moustakas, John [Department of Physics, Siena College, 515 Loudon Rd., Loudonville, NY 12211 (United States); Blanton, Michael R.; Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Burles, Scott M. [D.E. Shaw and Co. L.P, 20400 Stevens Creek Blvd., Suite 850, Cupertino, CA 95014 (United States); Coil, Alison L.; Aird, James; Mendez, Alexander J. [Department of Physics, Center for Astrophysics and Space Sciences, University of California, 9500 Gilman Dr., La Jolla, San Diego, CA 92093 (United States); Eisenstein, Daniel J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, MS 20, Cambridge, MA 02138 (United States); Wong, Kenneth C. [Steward Observatory, The University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Zhu, Guangtun [Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Bernstein, Rebecca A. [Department of Astronomy and Astrophysics, UCA/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Bolton, Adam S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States)

    2013-04-20T23:59:59.000Z

    The PRIsm MUlti-object Survey (PRIMUS) is a spectroscopic galaxy redshift survey to z {approx} 1 completed with a low-dispersion prism and slitmasks allowing for simultaneous observations of {approx}2500 objects over 0.18 deg{sup 2}. The final PRIMUS catalog includes {approx}130,000 robust redshifts over 9.1 deg{sup 2}. In this paper, we summarize the PRIMUS observational strategy and present the data reduction details used to measure redshifts, redshift precision, and survey completeness. The survey motivation, observational techniques, fields, target selection, slitmask design, and observations are presented in Coil et al. Comparisons to existing higher-resolution spectroscopic measurements show a typical precision of {sigma}{sub z}/(1 + z) = 0.005. PRIMUS, both in area and number of redshifts, is the largest faint galaxy redshift survey completed to date and is allowing for precise measurements of the relationship between active galactic nuclei and their hosts, the effects of environment on galaxy evolution, and the build up of galactic systems over the latter half of cosmic history.

  13. Competitive Reduction of Pertechnetate (99TcO4?) by Dissimilatory Metal Reducing Bacteria and Biogenic Fe(II)

    SciTech Connect (OSTI)

    Plymale, Andrew E.; Fredrickson, Jim K.; Zachara, John M.; Dohnalkova, Alice; Heald, Steve M.; Moore, Dean A.; Kennedy, David W.; Marshall, Matthew J.; Wang, Chong M.; Resch, Charles T.; Nachimuthu, Ponnusamy

    2011-02-01T23:59:59.000Z

    The fate of pertechnetate (99Tc(VII)O4 -) during bioreduction was investigated in the presence of 2-line ferrihydrite (Fh) and various dissimilatory metal reducing bacteria (DMRB) (Geobacter, Anaeromyxobacter, Shewanella) in comparison with TcO4 - bioreduction in the absence of Fh. In the presence of Fh, Tc was present primarily as a fine-grained Tc(IV)/Fe precipitate that was distinct from the Tc(IV)O2 ·nH2O solids produced by direct biological Tc(VII) reduction. Aqueous Tc concentrations (<0.2 ?m) in the bioreduced Fh suspensions (1.7 to 3.2 × 10-9 mol L-1) were over 1 order of magnitude lower than when TcO4 - was biologically reduced in the absence of Fh (4.0 × 10-8 to 1.0 × 10-7 mol L-1). EXAFS analyses of the bioreduced Fh-Tc products were consistent with variable chain length Tc-O octahedra bonded to Fe-O octahedra associated with the surface of the residual or secondary Fe(III) oxide. In contrast, biogenic TcO2 ·nH2O had significantly more Tc-Tc second neighbors and a distinct long-range order consistent with small particle polymers of TcO2. In Fe-rich subsurface sediments, the reduction of Tc(VII) by Fe(II) may predominate over direct microbial pathways, potentially leading to lower concentrations of aqueous 99Tc(IV).

  14. Nonlinear friction in quantum mechanics

    E-Print Network [OSTI]

    Roumen Tsekov

    2010-03-01T23:59:59.000Z

    The effect of nonlinear friction forces in quantum mechanics is studied via dissipative Madelung hydrodynamics. A new thermo-quantum diffusion equation is derived, which is solved for the particular case of quantum Brownian motion with a cubic friction. It is extended also by a chemical reaction term to describe quantum reaction-diffusion systems with nonlinear friction as well.

  15. PEBBLES Simulation of Static Friction and New Static Friction Benchmark

    SciTech Connect (OSTI)

    Joshua J. Cogliati; Abderrafi M. Ougouag

    2010-05-01T23:59:59.000Z

    Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. This paper documents the PEBBLES static friction model. This model uses a three dimensional differential static friction approximation extended from the two dimensional Cundall and Strack model. The derivation of determining the rotational transformation of pebble to pebble static friction force is provided. A new implementation for a differential rotation method for pebble to container static friction force has been created. Previous published methods are insufficient for pebble bed reactor geometries. A new analytical static friction benchmark is documented that can be used to verify key static friction simulation parameters. This benchmark is based on determining the exact pebble to pebble and pebble to container static friction coefficients required to maintain a stable five sphere pyramid.

  16. Reduction of iron-oxide-carbon composites: part II. Rates of reduction of composite pellets in a rotary hearth furnace simulator

    SciTech Connect (OSTI)

    Halder, S.; Fruehan, R.J. [Praxair Inc., Tonawanda, NY (United States). Praxair Technological Center

    2008-12-15T23:59:59.000Z

    A new ironmaking concept is being proposed that involves the combination of a rotary hearth furnace (RHF) with an iron-bath smelter. The RHF makes use of iron-oxide-carbon composite pellets as the charge material and the final product is direct-reduced iron (DRI) in the solid or molten state. This part of the research includes the development of a reactor that simulated the heat transfer in an RHF. The external heat-transport and high heating rates were simulated by means of infrared (IR) emitting lamps. The reaction rates were measured by analyzing the off-gas and computing both the amount of CO and CO{sub 2} generated and the degree of reduction. The reduction times were found to be comparable to the residence times observed in industrial RHFs. Both artificial ferric oxide (PAH) and naturally occurring hematite and taconite ores were used as the sources of iron oxide. Coal char and devolatilized wood charcoal were the reductants. Wood charcoal appeared to be a faster reductant than coal char. However, in the PAH-containing pellets, the reverse was found to be true because of heat-transfer limitations. For the same type of reductant, hematite-containing pellets were observed to reduce faster than taconite-containing pellets because of the development of internal porosity due to cracking and fissure formation during the Fe2O{sub 3}-to-Fe3O{sub 4} transition. This is, however, absent during the reduction of taconite, which is primarily Fe3O{sub 4}. The PAH-wood-charcoal pellets were found to undergo a significant amount of swelling at low-temperature conditions, which impeded the external heat transport to the lower layers. If the average degree of reduction targeted in an RHF is reduced from 95 to approximately 70 pct by coupling the RHF with a bath smelter, the productivity of the RHF can be enhanced 1.5 to 2 times. The use of a two- or three-layer bed was found to be superior to that of a single layer, for higher productivities.

  17. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect (OSTI)

    Victor Wong; Tian Tian; Luke Moughon; Rosalind Takata; Jeffrey Jocsak

    2006-03-31T23:59:59.000Z

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis is being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston and piston-ring dynamic and friction models have been developed and applied that illustrate the fundamental relationships among mechanical, surface/material and lubricant design parameters and friction losses. Demonstration of low-friction ring-pack designs in the Waukesha VGF 18GL engine confirmed total engine FEMP (friction mean effective pressure) reduction of 7-10% from the baseline configuration without significantly increasing oil consumption or blow-by flow. This represents a substantial (30-40%) reduction of the ringpack friction alone. The measured FMEP reductions were in good agreement with the model predictions. Further improvements via piston, lubricant, and surface designs offer additional opportunities. Tests of low-friction lubricants are in progress and preliminary results are very promising. The combined analysis of lubricant and surface design indicates that low-viscosity lubricants can be very effective in reducing friction, subject to component wear for extremely thin oils, which can be mitigated with further lubricant formulation and/or engineered surfaces. Hence a combined approach of lubricant design and appropriate wear reduction offers improved potential for minimum engine friction loss. Piston friction studies indicate that a flatter piston with a more flexible skirt, together with optimizing the waviness and film thickness on the piston skirt offer significant friction reduction. Combined with low-friction ring-pack, material and lubricant parameters, a total power cylinder friction reduction of 30-50% is expected, translating to an engine efficiency increase of two percentage points from its current baseline towards the goal of 50% ARES engine efficiency. The design strategies developed in this study have promising potential for application in all modern reciprocating engines as they represent simple, low-cost methods to extract significant fuel savings. The current program has possible spinoffs and applications in other industries as well, including transportation, CHP, and diesel power generation. The progress made in this program has wide engine efficiency implications, and potential deployment of low-friction engine components or lubricants in the near term is possible as current investigations continue.

  18. Reductive Biotransformation of Fe in Shale-Limestone Saprolite Containing Fe(III) Oxides and Fe(II)/Fe(III) Phyllosilicates

    SciTech Connect (OSTI)

    Kukkadapu, Ravi K.; Zachara, John M.; Fredrickson, Jim K.; McKinley, James P.; Kennedy, David W.; Smith, Steven C.; Dong, Hailiang

    2006-07-15T23:59:59.000Z

    A <2.0-mm fraction of a mineralogically complex subsurface sediment containing goethite and Fe(II)/Fe(III) phyllosilicates was incubated with Shewanella putrefaciens (strain CN32) and lactate at circumneutral pH under anoxic conditions to investigate electron acceptor preference and the nature of the resulting biogenic Fe(II) fraction. Anthraquinone-2,6-disulfonate (AQDS), an electron shuttle, was included in select treatments to enhance bioreduction and subsequent biomineralization. The sediment was highly aggregated and contained two distinct clast populations: i) a highly weathered one with “sponge-like” internal porosity, large mineral crystallites, and Fe-containing micas, and ii) a dense, compact one with fine-textured Fe-containing illite and nano-sized goethite, as revealed by various forms of electron microscopic analyses. Approximately 10 to 15% of the Fe(III)TOT was bioreduced by CN32 over 60 d in media without AQDS, whereas 24% and 35% of the Fe(III)TOT was bioreduced by CN32 after 40 and 95 d in media with AQDS. Little or no Fe2+, Mn, Si, Al, and Mg were evident in aqueous filtrates after reductive incubation. Mössbauer measurements on the bioreduced sediments indicated that both goethite and phyllosilicate Fe(III) were partly reduced without bacterial preference. Goethite was more extensively reduced in the presence of AQDS whereas phyllosilicate Fe(III) reduction was not influenced by AQDS. Biogenic Fe(II) resulting from phyllosilicate Fe(III) reduction remained in a layer-silicate environment that displayed enhanced solubility in weak acid. The mineralogic nature of the goethite biotransformation product was not determined. Chemical and cryogenic Mössbauer measurements, however, indicated that the transformation product was not siderite, green rust, magnetite, Fe(OH)2, or Fe(II) adsorbed on phyllosilicate or bacterial surfaces. Several lines of evidence suggested that biogenic Fe(II) existed as surface associated phase on the residual goethite, and/or as a Fe(II)-Al coprecipitate. Sediment aggregation and mineral physical and/or chemical factors were demonstrated to play a major role on the nature and location of the biotransformation reaction and its products.

  19. Friction surfaced Stellite6 coatings

    SciTech Connect (OSTI)

    Rao, K. Prasad; Damodaram, R. [Department of Metallurgical and Materials Engineering - Indian Institute of Technology Madras, Chennai 600 036 (India); Rafi, H. Khalid, E-mail: khalidrafi@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Ram, G.D. Janaki [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Reddy, G. Madhusudhan [Metal Joining Group, Defence Metallurgical Research Laboratory (DMRL) Kanchanbagh, Hyderabad 500 058 (India); Nagalakshmi, R. [Welding Research Institute, Bharat Heavy Electricals Limited, Tiruchirappalli 620 014 (India)

    2012-08-15T23:59:59.000Z

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: Black-Right-Pointing-Pointer Stellite6 used as coating material for friction surfacing. Black-Right-Pointing-Pointer Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. Black-Right-Pointing-Pointer Finer and uniformly distributed carbides in friction surfaced coatings. Black-Right-Pointing-Pointer Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  20. Friction of wood on steel.

    E-Print Network [OSTI]

    Koubek, Radek

    2014-01-01T23:59:59.000Z

    ?? This thesis deals with the experimental description of friction between steel and wood materials, specifically laminated veneer lumber (LVL) and pine wood with two… (more)

  1. The role of crystallography and nanostructures on metallic friction.

    SciTech Connect (OSTI)

    Michael, Joseph Richard; Prasad, Somuri V.; Battaile, Corbett Chandler; Majumdar, Bhaskar Sinha (New Mexico Institute of Mining & Technology, Socorro, NM); Kotula, Paul Gabriel

    2010-06-01T23:59:59.000Z

    In ductile metals, sliding contact is often accompanied by severe plastic deformation localized to a small volume of material adjacent to the wear surface. During the initial run-in period, hardness, grain structure and crystallographic texture of the surfaces that come into sliding contact undergo significant changes, culminating in the evolution of subsurface layers with their own characteristic features. Here, a brief overview of our ongoing research on the fundamental phenomena governing the friction-induced recrystallization in single crystal metals, and how these recrystallized structures with nanometer-size grains would in turn influence metallic friction will be presented. We have employed a novel combination of experimental tools (FIB, EBSD and TEM) and an analysis of the critical resolved shear stress (RSS) on the twelve slip systems of the FCC lattice to understand the evolution of these friction-induced structures in single crystal nickel. The later part of the talk deals with the mechanisms of friction in nanocrystalline Ni films. Analyses of friction-induced subsurfaces seem to confirm that the formation of stable ultrafine nanocrystalline layers with 2-10 nm grains changes the deformation mechanism from the traditional dislocation mediated one to that is predominantly controlled by grain boundaries, resulting in significant reductions in the coefficient friction.

  2. Simulation of Reduction of Cr(VI) by Fe(II) Produced Electrochemically in a Parallel-Plate Electrochemical Reactor

    E-Print Network [OSTI]

    at the cathode, electrocoagulation uses electricity to produce a reducing agent ferrous ions from an iron anode the reduction of Cr VI by permeable reactive barriers. Gheju and Lovi7 reported that the re- duction of Cr VI

  3. Elastic model of dry friction

    SciTech Connect (OSTI)

    Larkin, A. I.; Khmelnitskii, D. E., E-mail: dekl2@cam.ac.uk [Landau Institute for Theoretical Physics (Russian Federation)

    2013-09-15T23:59:59.000Z

    Friction of elastic bodies is connected with the passing through the metastable states that arise at the contact of surfaces rubbing against each other. Three models are considered that give rise to the metastable states. Friction forces and their dependence on the pressure are calculated. In Appendix A, the contact problem of elasticity theory is solved with adhesion taken into account.

  4. II

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C. 20545*. . : '* FEB1f\lMUC4cb90,fioml7aa AMY yII

  5. II

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C. 20545*. . : '* FEB1f\lMUC4cb90,fioml7aa AMY yII

  6. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect (OSTI)

    Victor Wong; Tian Tian; Luke Moughon; Rosalind Takata; Jeffrey Jocsak

    2005-09-30T23:59:59.000Z

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis is being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston and piston-ring dynamic and friction models have been developed and applied that illustrate the fundamental relationships between design parameters and friction losses. Low friction ring designs have already been recommended in a previous phase, with full-scale engine validation partially completed. Current accomplishments include the addition of several additional power cylinder design areas to the overall system analysis. These include analyses of lubricant and cylinder surface finish and a parametric study of piston design. The Waukesha engine was found to be already well optimized in the areas of lubricant, surface skewness and honing cross-hatch angle, where friction reductions of 12% for lubricant, and 5% for surface characteristics, are projected. For the piston, a friction reduction of up to 50% may be possible by controlling waviness alone, while additional friction reductions are expected when other parameters are optimized. A total power cylinder friction reduction of 30-50% is expected, translating to an engine efficiency increase of two percentage points from its current baseline towards the goal of 50% efficiency. Key elements of the continuing work include further analysis and optimization of the engine piston design, in-engine testing of recommended lubricant and surface designs, design iteration and optimization of previously recommended technologies, and full-engine testing of a complete, optimized, low-friction power cylinder system.

  7. Fe(II)- and Sulfide-Facilitated Reduction of 99Tc(VII)O4- in Microbially Reduced Hyporheic Zone Sediments

    SciTech Connect (OSTI)

    Lee, Ji-Hoon; Zachara, John M.; Fredrickson, Jim K.; Heald, Steve M.; McKinley, James P.; Plymale, Andrew E.; Resch, Charles T.; Moore, Dean A.

    2014-07-01T23:59:59.000Z

    Redox-reactive, biogeochemical phases generated by reductive microbial activity in hyporheic zone sediments from a dynamic groundwater-river interaction zone were evaluated for their ability to reduce soluble pertechnetate [99Tc(VII)O4-] to less soluble Tc(IV). The sediments were bioreduced by indigenous microorganisms that were stimulated by organic substrate addition in synthetic groundwater with or without sulfate. In most treatments, 20 µmol L-1 initial aqueous Tc(VII) was reduced to near or below detection (3.82×10-9 mol L-1) over periods of days to months in suspensions of variable solids concentrations. Native sediments containing significant lithogenic Fe(II) in various phases were, in contrast, unreactive with Tc(VII). The reduction rates in the bioreduced sediments increased with increases in sediment mass, in proportion to weak acid-extractable Fe(II) and sediment-associated sulfide (AVS). The rate of Tc(VII) reduction was first order with respect to both aqueous Tc(VII) concentration and sediment mass, but correlations between specific reductant concentrations and reaction rate were not found. X-ray microprobe measurements revealed a strong correlation between Tc hot spots and Fe-containing mineral particles in the sediment. However, only a portion of Fe-containing particles were Tc-hosts. The Tc-hot spots displayed a chemical signature (by EDXRF) similar to pyroxene. The application of autoradiography and electron microprobe allowed further isolation of Tc-containing particles that were invariably found to be ca 100 µm aggregates of primary mineral material embedded within a fine-grained phyllosilicate matrix. EXAFS spectroscopy revealed that the Tc(IV) within these were a combination of a Tc(IV)O2-like phase and Tc(IV)-Fe surface clusters, with a significant fraction of a TcSx-like phase in sediments incubated with SO42-. AVS was implicated as a more selective reductant at low solids concentration even though its concentration was below that required for stoichiometric reduction of Tc(VII). These results demonstrate that composite mineral aggregates may be redox reaction centers in coarse-textured hyporheic zone sediments regardless of the dominant anoxic biogeochemical processes.

  8. Reduction And Stabilization (Immobilization) Of Pertechnetate To An Immobile Reduced Technetium Species Using Tin(II) Apatite

    SciTech Connect (OSTI)

    Duncan, J. B.

    2012-11-02T23:59:59.000Z

    Synthetic tin(II)apatite reduces pertechnetate from the mobile +7 to a non-mobile oxidation state and sequesters the technetium, preventing re-oxidization to mobile +7 state under acidic or oxygenated conditions. Previous work indicated technetium reacted Sn(II)apatite can achieve an ANSI leachability index of 12.8 in Cast Stone. An effect by pH is observed on the distribution coefficient, the highest distribution coefficient being l70,900 observed at pH levels of 2.5 to 10.2. The tin apatite was resistant to releasing technetium under test conditions.

  9. Energy Efficiency/Renewable Energy Impact in the Texas Emissions Reduction Plan (TERP) Volume II- Technical Report

    E-Print Network [OSTI]

    Haberl, J.; Culp, C.; Yazdani, B.; Lewis, C.; Liu, Z.; Baltazar-Cervantes, J. C.; Mukhopadhyay, J.; Gilman, D.; Degelman, L.; McKelvey, K.; Claridge, D.

    .E. December 2010 ENERGY SYSTEMS LABORATORY Texas Engineering Experiment Station Texas A&M University System 2009 TERP Report, Vol. II, p. 1 December 2010 Energy Systems Laboratory, Texas A&M University System ENERGY SYSTEMS... Plan 1 Executive Summary The Energy Systems Laboratory (Laboratory), at the Texas Engineering Experiment Station of the Texas A&M University System, in fulfillment of its responsibilities under Texas Health and Safety Code Ann. ? 388.003 (e...

  10. Implications of Strong-Rate-Weakening Friction

    E-Print Network [OSTI]

    Greer, Julia R.

    Implications of Strong-Rate- Weakening Friction for the Length-Scale Dependence of the Strength · Rapid transitions between high static friction and very low dynamic friction · Leads to slip-pulse rupture · Slip pulses are extremely localized and have strong positive feedback between friction and slip

  11. Modelling of friction stir welding

    E-Print Network [OSTI]

    Colegrove, Paul Andrew

    This thesis investigates the modelling of friction stir welding (FSW). FSW is a relatively new welding process where a rotating non-consumable tool is used to join two materials through high temperature deformation. The aim of the thesis...

  12. Rubber friction and tire dynamics

    E-Print Network [OSTI]

    B. N. J. Persson

    2010-07-16T23:59:59.000Z

    We propose a simple rubber friction law, which can be used, e.g., in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (B.N.J. Persson, J. Phys.: Condensed Matter 18, 7789 (2006)). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to calculate accurate mu-slip (and the self-aligning torque) curves for braking and cornering or combined motion (e.g., braking during cornering). We present numerical results which illustrate the theory. Simulations of Anti-Blocking System (ABS) braking are performed using two simple control algorithms.

  13. Finite Element Analysis of the Amontons-Coulomb's Model using Local and Global Friction Tests

    SciTech Connect (OSTI)

    Oliveira, M. C.; Menezes, L. F.; Ramalho, A. [CEMUC, Department of Mechanical Engineering, University of Coimbra, Polo II, Rua Luis Reis Santos, Pinhal de Marrocos, 3030-788 Coimbra (Portugal); Alves, J. L. [Department of Mechanical Engineering, University of Minho, Campus de Azurem, 4800-058, Guimaraes (Portugal)

    2011-05-04T23:59:59.000Z

    In spite of the abundant number of experimental friction tests that have been reported, the contact with friction modeling persists to be one of the factors that determine the effectiveness of sheet metal forming simulation. This difficulty can be understood due to the nature of the friction phenomena, which comprises the interaction of different factors connected to both sheet and tools' surfaces. Although in finite element numerical simulations friction models are commonly applied at the local level, they normally rely on parameters identified based on global experimental tests results. The aim of this study is to analyze the applicability of the Amontons-Coulomb's friction coefficient identified using complementary tests: (i) load-scanning, at the local level and (ii) draw-bead, at the global level; to the numerical simulation of sheet metal forming processes.

  14. In-situ measurement of skin friction and point bearing

    E-Print Network [OSTI]

    Rehmet, Joseph Don

    1970-01-01T23:59:59.000Z

    '-7. 80' Device Limiting Values (psf) 8 ft Pile Limiting Values (psf) 205 952 Unconfined Shear Strength (psf) 1095 1915 '/26 l 4I'26 l Srmur? taneous I-2-1 I-2-2 I-2-3 I-2-4 2 I gll 2'-8" 5 '-'4" 5 I 4II Tip = 1880 Friction.... 02 5. 26 2. 34 3. 74 3. 71 . 233 . 396 . 337 . 364 . 318 TABLE VI FRICTION DARING DATA Height of P P 'dy st P /P (lbs) (lbs) dy st Pile Displacement Velocity J' (fps) (sec/ft) , 0. 35 O I 21 811 2'-8" C I I II J -4 5'-4" 51...

  15. Friction Anisotropy: A unique and intrinsic property of decagonal quasicrystals

    E-Print Network [OSTI]

    Park, Jeong Young

    2008-01-01T23:59:59.000Z

    Quasi-Crystalline Low-Friction Coatings. Journal ofContact Mechanics, Friction and Adhesion with Application toEds. ), Fundamentals of Friction and Wear, Springer Berlin

  16. Epistemic Friction: Reflections on Knowledge, Truth, and Logic

    E-Print Network [OSTI]

    Sher, Gila

    2010-01-01T23:59:59.000Z

    ARTICLE Epistemic Friction: Re?ections on Knowledge, Truth,requires both freedom and friction. Freedom to set up ourprograms, etc. , and friction (constraint) coming from two

  17. Friction welded nonconsumable electrode assembly and use thereof for electrolytic production of metals and silicon

    DOE Patents [OSTI]

    Byrne, Stephen C. (Monroeville, PA); Ray, Siba P. (Pittsburgh, PA); Rapp, Robert A. (Columbus, OH)

    1984-01-01T23:59:59.000Z

    A nonconsumable electrode assembly suitable for use in the production of metal by electrolytic reduction of a metal compound dissolved in a molten salt, the assembly comprising a metal conductor and a ceramic electrode body connected by a friction weld between a portion of the body having a level of free metal or metal alloy sufficient to effect such a friction weld and a portion of the metal conductor.

  18. Vacuum friction in rotating particles

    E-Print Network [OSTI]

    A. Manjavacas; F. J. García de Abajo

    2010-09-21T23:59:59.000Z

    We study the frictional torque acting on particles rotating in empty space. At zero temperature, vacuum friction transforms mechanical energy into light emission and produces particle heating. However, particle cooling relative to the environment occurs at finite temperatures and low rotation velocities. Radiation emission is boosted and its spectrum significantly departed from a hot-body emission profile as the velocity increases. Stopping times ranging from hours to billions of years are predicted for materials, particle sizes, and temperatures accessible to experiment. Implications for the behavior of cosmic dust are discussed.

  19. Low-Engine-Friction Technology for Advanced Natural-Gas Reciprocating Engines

    SciTech Connect (OSTI)

    Victor Wong; Tian Tian; G. Smedley; L. Moughon; Rosalind Takata; J. Jocsak

    2006-11-30T23:59:59.000Z

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis has been followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. In this program, a detailed set of piston and piston-ring dynamic and friction models have been adapted and applied that illustrate the fundamental relationships among mechanical, surface/material and lubricant design parameters and friction losses. Demonstration of low-friction ring-pack designs in the Waukesha VGF 18GL engine confirmed ring-pack friction reduction of 30-40%, which translates to total engine FEMP (friction mean effective pressure) reduction of 7-10% from the baseline configuration without significantly increasing oil consumption or blow-by flow. The study on surface textures, including roughness characteristics, cross hatch patterns, dimples and grooves have shown that even relatively small-scale changes can have a large effect on ring/liner friction, in some cases reducing FMEP by as much as 30% from a smooth surface case. The measured FMEP reductions were in good agreement with the model predictions. The combined analysis of lubricant and surface design indicates that low-viscosity lubricants can be very effective in reducing friction, subject to component wear for extremely thin oils, which can be mitigated with further lubricant formulation and/or engineered surfaces. Hence a combined approach of lubricant design and appropriate wear reduction offers improved potential for minimum engine friction loss. Testing of low-friction lubricants showed that total engine FMEP reduced by up to {approx}16.5% from the commercial reference oil without significantly increasing oil consumption or blow-by flow. Piston friction studies indicate that a flatter piston with a more flexible skirt, together with optimizing the waviness and film thickness on the piston skirt offer significant friction reduction. Combined with low-friction ring-pack, material and lubricant parameters, a total power cylinder friction reduction of 30-50% is expected, translating to an engine efficiency increase of two percentage points from its current baseline towards the goal of 50% ARES engine efficiency. The design strategies developed in this study have promising potential for application in all modern reciprocating engines as they represent simple, low-cost methods to extract significant fuel savings. The current program has possible spinoffs and applications in other industries as well, including transportation, CHP, and diesel power generation. The progress made in this program has wide engine efficiency implications, and potential deployment of low-friction engine components or lubricants in the near term is quite possible.

  20. The Power of Friction: Quantifying the ``Goodness'' of Frictional Grasps \\Lambda

    E-Print Network [OSTI]

    Mishra, Bud

    The Power of Friction: Quantifying the ``Goodness'' of Frictional Grasps \\Lambda Marek Teichmann of fingers, coefficient of friction and the the goodness of a grasp. In particular, we give a general framework for defining a grasp metric that takes friction into account. Our approach rectifies a flaw

  1. Automotive friction-induced noises A. Elmaiana

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Automotive friction-induced noises A. Elmaiana , J.-M. Duffala , F. Gautiera , C. Pezeratb and J, France 3143 #12;Friction-induced noises are numerous in the automotive field. They also involve a large friction-induced noises with simple structures and automotive materials. Qualitative sensitivity studies

  2. Pulling by Pushing, Slip with Infinite Friction,

    E-Print Network [OSTI]

    Pulling by Pushing, Slip with Infinite Friction, and Perfectly Rough Surfaces Kevin M. Lynch the two objects even with an infinite coefficient of friction. Thus the common conception that infinite friction prevents slip is in error. This paper shows examples of the phenomena with both quasi

  3. Friction in full view A. P. Merklea

    E-Print Network [OSTI]

    Marks, Laurence D.

    Friction in full view A. P. Merklea and L. D. Marksb Materials Science and Engineering proposed friction mechanisms explaining the unique tribological properties of graphite. Wear of graphite chemical or struc- tural information from the interface during a friction experi- ment. Examples

  4. The friction of wrinkles Hamid Mohammadi1

    E-Print Network [OSTI]

    Mueser, Martin

    The friction of wrinkles Hamid Mohammadi1 and Martin H. M¨user2 1 Dept. of Applied Mathematics pattern has asymmetries not present in the counterbody. The instabilities then cause Coulomb's friction Likewise, the presence of friction - as observed for the much investigated keratocytes on silicon rubber15

  5. Tool Wear in Friction Drilling

    SciTech Connect (OSTI)

    Miller, Scott F [ORNL; Blau, Peter Julian [ORNL; Shih, Albert J. [University of Michigan

    2007-01-01T23:59:59.000Z

    This study investigated the wear of carbide tools used in friction drilling, a nontraditional hole-making process. In friction drilling, a rotating conical tool uses the heat generated by friction to soften and penetrate a thin workpiece and create a bushing without generating chips. The wear of a hard tungsten carbide tool used for friction drilling a low carbon steel workpiece has been investigated. Tool wear characteristics were studied by measuring its weight change, detecting changes in its shape with a coordinate measuring machine, and making observations of wear damage using scanning electron microscopy. Energy dispersive spectroscopy was applied to analyze the change in chemical composition of the tool surface due to drilling. In addition, the thrust force and torque during drilling and the hole size were measured periodically to monitor the effects of tool wear. Results indicate that the carbide tool is durable, showing minimal tool wear after drilling 11000 holes, but observations also indicate progressively severe abrasive grooving on the tool tip.

  6. Friction forces in cosmological models

    E-Print Network [OSTI]

    Donato Bini; Andrea Geralico; Daniele Gregoris; Sauro Succi

    2014-08-23T23:59:59.000Z

    We investigate the dynamics of test particles undergoing friction forces in a Friedmann-Robertson-Walker (FRW) spacetime. The interaction with the background fluid is modeled by introducing a Poynting-Robertson-like friction force in the equations of motion, leading to measurable (at least in principle) deviations of the particle trajectories from geodesic motion. The effect on the peculiar velocities of the particles is investigated for various equations of state of the background fluid and different standard cosmological models. The friction force is found to have major effects on particle motion in closed FRW universes, where it turns the time-asymptotic value (approaching the recollapse) of the peculiar particle velocity from ultra-relativistic (close to light speed) to a co-moving one, i.e., zero peculiar speed. On the other hand, for open or flat universes the effect of the friction is not so significant, because the time-asymptotic peculiar particle speed is largely non-relativistic also in the geodesic case.

  7. Dynamical friction on satellite galaxies

    E-Print Network [OSTI]

    Michiko Fujii; Yoko Funato; Junichiro Makino

    2005-11-22T23:59:59.000Z

    For a rigid model satellite, Chandrasekhar's dynamical friction formula describes the orbital evolution quite accurately, when the Coulomb logarithm is chosen appropriately. However, it is not known if the orbital evolution of a real satellite with the internal degree of freedom can be described by the dynamical friction formula. We performed N-body simulation of the orbital evolution of a self-consistent satellite galaxy within a self-consistent parent galaxy. We found that the orbital decay of the simulated satellite is significantly faster than the estimate from the dynamical friction formula. The main cause of this discrepancy is that the stars stripped out of the satellite are still close to the satellite, and increase the drag force on the satellite through two mechanisms. One is the direct drag force from particles in the trailing tidal arm, a non-axisymmetric force that slows the satellite down. The other is the indirect effect that is caused by the particles remaining close to the satellite after escape. The force from them enhances the wake caused in the parent galaxy by dynamical friction, and this larger wake in turn slows the satellite down more than expected from the contribution of its bound mass. We found these two have comparable effects, and the combined effect can be as large as 20% of the total drag force on the satellite.

  8. Wall-pressure and PIV analysis for microbubble drag reduction investigation

    E-Print Network [OSTI]

    Dominguez Ontiveros, Elvis Efren

    2005-11-01T23:59:59.000Z

    friction reductions were observed when the microbubbles were injected. Several measurements of wall-pressure were taken at various Reynolds numbers that ranged from 300 up to 6154. No significant drag reduction was observed for flows in the laminar range...

  9. Friction and Wear Reduction in Diesel Engine Valve Trains

    Broader source: Energy.gov (indexed) [DOE]

    commercial exhaust valve * Surface damage from 20,000 impacts displays micro-welding, plastic deformation, and transfer. 9 Managed by UT-Battelle for the Department of Energy...

  10. Thermo-Wetting and Friction Reduction Characterization of

    E-Print Network [OSTI]

    Hidrovo, Carlos H.

    such surfaces include frost prevention on aircraft flight surfaces to self-cleaning features on solar energy panels [1,5]. One way to achieve superhydrophobicity is through the micro- geometry modification of low energy surfaces. Two models repre- sent the wetting behavior of such microtextured surfaces: the Wenzel

  11. Efficiency Improvement through Reduction in Friction and Wear in Powertrain

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarly Career Scientists'Montana.Program - LibbyofThisStatement Tuesday,Department

  12. Engine Friction Reduction Through Surface Finish and Coatings | Department

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-UpHeat PumpRecord ofESPCof Energy 12, 2004Department ofEnforcingVehicleof Energy

  13. Heavy Truck Friction & Wear Reduction Technologies | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-UpHeatMulti-Dimensional Subject:Ground Hawaii CleanHeat Pump WaterPresentation

  14. An integrated surface technology for friction reduction in vehicles |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-Up fromDepartment ofEnergy Natural Gas:Austin,AnAn Exploration of

  15. Rubber friction on smooth surfaces

    E-Print Network [OSTI]

    B. N. J. Persson; A. I. Volokitin

    2006-07-04T23:59:59.000Z

    We study the sliding friction for viscoelastic solids, e.g., rubber, on hard flat substrate surfaces. We consider first the fluctuating shear stress inside a viscoelastic solid which results from the thermal motion of the atoms or molecules in the solid. At the nanoscale the thermal fluctuations are very strong and give rise to stress fluctuations in the MPa-range, which is similar to the depinning stresses which typically occur at solid-rubber interfaces, indicating the crucial importance of thermal fluctuations for rubber friction on smooth surfaces. We develop a detailed model which takes into account the influence of thermal fluctuations on the depinning of small contact patches (stress domains) at the rubber-substrate interface. The theory predicts that the velocity dependence of the macroscopic shear stress has a bell-shaped f orm, and that the low-velocity side exhibits the same temperature dependence as the bulk viscoelastic modulus, in qualitative agreement with experimental data. Finally, we discuss the influence of small-amplitude substrate roughness on rubber sliding friction.

  16. EVALUATION OF A LOW FRICTION - HIGH EFFICIENCY ROLLER BEARING ENGINE

    SciTech Connect (OSTI)

    Kolarik, Robert V. II; Shattuck, Charles W.; Copper, Anthony P.

    2009-06-30T23:59:59.000Z

    This Low Friction (High Efficiency Roller Bearing) Engine (LFE) report presents the work done by The Timken Company to conduct a technology demonstration of the benefits of replacing hydrodynamic bearings with roller bearings in the crankshaft and camshaft assemblies of an internal combustion engine for the purpose of collecting data sufficient to prove merit. The engines in the present study have been more extensively converted to roller bearings than any previous studies (40 needle roller bearings per engine) to gain understanding of the full potential of application of bearing technology. The project plan called for comparative testing of a production vehicle which was already respected for having demonstrated low engine friction levels with a rollerized version of that engine. Testing was to include industry standard tests for friction, emissions and fuel efficiency conducted on instrumented dynamometers. Additional tests for fuel efficiency, cold start resistance and other measures of performance were to be made in the actual vehicle. Comparative measurements of noise, vibration and harshness (NVH), were planned, although any work to mitigate the suspected higher NVH level in the rollerized engine was beyond the scope of this project. Timken selected the Toyota Avalon with a 3.5L V-6 engine as the test vehicle. In an attempt to minimize cost and fabrication time, a ‘made-from’ approach was proposed in which as many parts as possible would be used or modified from production parts to create the rollerized engine. Timken commissioned its test partner, FEV Engine Technology, to do a feasibility study in which they confirmed that using such an approach was possible to meet the required dimensional restrictions and tolerances. In designing the roller bearing systems for the crank and cam trains, Timken utilized as many production engine parts as possible. The crankshafts were produced from production line forgings, which use Timken steel, modified with special machining and heat treatment. Timken designed and manufactured all of the roller bearing related components such as the thrust bearing package. The production connecting rods and camshafts could not be used for the roller bearing engine, so new ones were produced according to the team’s designs using Timken steel. The remaining miscellaneous components were designed and procured by FEV. Timken prepared a display version of the crankshaft portion of the production engine without connecting rods which could be driven by a motor through a cogged-belt and electrically actuated clutch arrangement. A modified version was also made in which the engine was outfitted with roller bearings on the main bearing positions. Preliminary tests showed that the rollerized engine was running with 1/3 less friction than the standard display engine. Additional friction testing and noise characterization was cut short because of shipping damage to the rollerized engine display and because of other project priorities. The team did successfully demonstrate the ability to package roller bearings satisfactorily in numerous locations in a typical automotive engine. The scope of this project did not include durability demonstration and that subject would have to be addressed in any follow-on work. In the actual test phase, the rollerized engine did show significantly less friction in motored dynamometer tests compared to its production equivalent. The 5-10% improvement measured in this study was about half that seen in other studies. However, the fired test results did not show a reduction in friction which did not match prior experience or expectations. Subsequent teardown and inspection of the rollerized engine revealed potential sources of excessive friction in the experimental application. These features would be eliminated in a design not based on modification of production parts. The team is confident (based on experience) that friction reduction would be realized with proper modifications.

  17. Rubber friction on (apparently) smooth lubricated surfaces

    E-Print Network [OSTI]

    M. Mofidi; B. Prakash; B. N. J. Persson; O. Albohl

    2007-10-18T23:59:59.000Z

    We study rubber sliding friction on hard lubricated surfaces. We show that even if the hard surface appears smooth to the naked eye, it may exhibit short wavelength roughness, which may give the dominant contribution to rubber friction. That is, the observed sliding friction is mainly due to the viscoelastic deformations of the rubber by the substrate surface asperities. The presented results are of great importance for rubber sealing and other rubber applications involving (apparently) smooth surfaces.

  18. Friction as Basis for a Phonon Maser

    E-Print Network [OSTI]

    Randall D. Peters

    2003-08-08T23:59:59.000Z

    Evidence is provided from experiment, for the hypothesis that defect organization (internal friction) is a means for operation of a phonon maser.

  19. Solid Friction from stick-slip to pinning and aging

    E-Print Network [OSTI]

    Tristan Baumberger; Christiane Caroli

    2005-06-24T23:59:59.000Z

    We review the present state of understanding of solid friction at low velocities and for systems with negligibly small wear effects. We first analyze in detail the behavior of friction at interfaces between wacroscopic hard rough solids, whose main dynamical features are well described by the Rice-Ruina rate and state dependent constitutive law. We show that it results from two combined effects : (i) the threshold rheology of nanometer-thick junctions jammed under confinement into a soft glassy structure (ii) geometric aging, i.e. slow growth of the real arrea of contact via asperity creep interrupted by sliding. Closer analysis leads to identifying a second aging-rejuvenation process, at work within the junctions themselves. We compare the effects of structural aging at such multicontact, very highly confined, interfaces with those met under different confinement levels, namely boundary lubricated contacts and extended adhesive interfaces involving soft materials (hydrogels, elastomers). This leads us to propose a classification of frictional junctions in terms of the relative importance of jamming and adsoprtion-induced metastability.

  20. Abstract--Friction modeling is essential for joint dynamic identification and control. Joint friction is composed of a

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Abstract--Friction modeling is essential for joint dynamic identification and control. Joint friction is composed of a viscous and a dry friction force. According to Coulomb law, dry friction depends linearly on the load in the transmission. However, in robotics field, a constant dry friction is frequently

  1. Some Hamiltonian Models of Friction

    E-Print Network [OSTI]

    Juerg Froehlich; Zhou Gang; Avy Soffer

    2010-11-04T23:59:59.000Z

    Mathematical results on some models describing the motion of a tracer particle through a Bose-Einstein condensate are described. In the limit of a very dense, very weakly interacting Bose gas and for a very large particle mass, the dynamics of the coupled system is determined by classical non-linear Hamiltonian equations of motion. The particle's motion exhibits deceleration corresponding to friction (with memory) caused by the emission of Cerenkov radiation of gapless modes into the gas. Precise results are stated and outlines of proofs are presented. Some technical details are deferred to forthcoming papers.

  2. Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction

    E-Print Network [OSTI]

    McLaskey, Gregory Christofer

    2011-01-01T23:59:59.000Z

    tremor like signals in friction experiments, Geophys. Res.analysis of the state- and rate-dependent friction law:Static friction, Physical Rev. B 59, 14313-14327. Bisschop,

  3. Dissimilar friction welding of titanium alloys to alloy 718

    SciTech Connect (OSTI)

    Kuo, M.; Albright, C.E.; Baeslack, W.A. III

    1994-12-31T23:59:59.000Z

    The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

  4. Comparison of Frictional Heating Models

    SciTech Connect (OSTI)

    Davies, Nicholas R [ORNL; Blau, Peter Julian [ORNL

    2013-10-01T23:59:59.000Z

    The purpose of this work was to compare the predicted temperature rises using four well-known models for frictional heating under a few selected conditions in which similar variable inputs are provided to each model. Classic papers by Archard, Kuhlmann-Wilsdorf, Lim and Ashby, and Rabinowicz have been examined, and a spreadsheet (Excel ) was developed to facilitate the calculations. This report may be used in conjunction with that spreadsheet. It explains the background, assumptions, and rationale used for the calculations. Calculated flash temperatures for selected material combinations, under a range of applied loads and sliding speeds, are tabulated. The materials include AISI 52100 bearing steel, CDA 932 bronze, NBD 200 silicon nitride, Ti-6Al-4V alloy, and carbon-graphite material. Due to the assumptions made by the different models, and the direct way in which certain assumed quantities, like heat sink distances or asperity dimensions, enter into the calculations, frictional hearing results may differ significantly; however, they can be similar in certain cases in light of certain assumptions that are shared between the models.

  5. Friction Coefficient for Quarks in Supergravity Duals

    E-Print Network [OSTI]

    E. Antonyan

    2006-11-22T23:59:59.000Z

    We study quarks moving in strongly-coupled plasmas that have supergravity duals. We compute the friction coefficient of strings dual to such quarks for general static supergravity backgrounds near the horizon. Our results also show that a previous conjecture on the bound has to be modified and higher friction coefficients can be achieved.

  6. Friction of Steel Sliding Under Boundary Lubrication Regime in...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Friction of Steel Sliding Under Boundary Lubrication Regime in Commercial Gear Oils at Elevated Temperatures Friction of Steel Sliding Under Boundary Lubrication Regime in...

  7. Friction forces on phase transition fronts

    SciTech Connect (OSTI)

    Mégevand, Ariel, E-mail: megevand@mdp.edu.ar [IFIMAR (CONICET–UNMdP), Departamento de Física, Facultad de Ciencias Exactas y Naturales, UNMdP, Deán Funes 3350, (7600) Mar del Plata (Argentina)

    2013-07-01T23:59:59.000Z

    In cosmological first-order phase transitions, the microscopic interaction of the phase transition fronts with non-equilibrium plasma particles manifests itself macroscopically as friction forces. In general, it is a nontrivial problem to compute these forces, and only two limits have been studied, namely, that of very slow walls and, more recently, ultra-relativistic walls which run away. In this paper we consider ultra-relativistic velocities and show that stationary solutions still exist when the parameters allow the existence of runaway walls. Hence, we discuss the necessary and sufficient conditions for the fronts to actually run away. We also propose a phenomenological model for the friction, which interpolates between the non-relativistic and ultra-relativistic values. Thus, the friction depends on two friction coefficients which can be calculated for specific models. We then study the velocity of phase transition fronts as a function of the friction parameters, the thermodynamic parameters, and the amount of supercooling.

  8. Viscous drag reduction in boundary layers

    SciTech Connect (OSTI)

    Bushnell, D.M.; Hefner, J.N.

    1990-01-01T23:59:59.000Z

    The present volume discusses the development status of stability theory for laminar flow control design, applied aspects of laminar-flow technology, transition delays using compliant walls, the application of CFD to skin friction drag-reduction, active-wave control of boundary-layer transitions, and such passive turbulent-drag reduction methods as outer-layer manipulators and complex-curvature concepts. Also treated are such active turbulent drag-reduction technique applications as those pertinent to MHD flow drag reduction, as well as drag reduction in liquid boundary layers by gas injection, drag reduction by means of polymers and surfactants, drag reduction by particle addition, viscous drag reduction via surface mass injection, and interactive wall-turbulence control.

  9. Dynamical Friction on extended perturbers

    E-Print Network [OSTI]

    O. Esquivel; B. Fuchs

    2008-04-01T23:59:59.000Z

    Following a wave-mechanical treatment we calculate the drag force exerted by an infinite homogeneous background of stars on a perturber as this makes its way through the system. We recover Chandrasekhar's classical dynamical friction (DF) law with a modified Coulomb logarithm. We take into account a range of models that encompasses all plausible density distributions for satellite galaxies by considering the DF exerted on a Plummer sphere and a perturber having a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.

  10. Energy Efficiency/Renewable Energy Impact in the Texas Emissions Reduction Plan (TERP), Volume II--Technical Report, Annual Report to the Texas Commission on Environmental Quality January 2008-December 2008

    E-Print Network [OSTI]

    Haberl, Jeff; Culp, Charles; Yazdani, Bahman; Gilman, Don; Muns, Shirley; Liu, Zi; Baltazar, Juan-Carlos; Mukhopadhyay, Jaya; Degelman, Larry; Claridge, David

    programs is 3.82 tons-NOx/day (12.1%), savings from SECO?s Senate Bill 5 program is 0.92 tons-NOx/day (2.9%), electricity savings from green power purchases (wind) 2008 TERP Report, Vol. II, p. 4 December 2009 Energy Systems Laboratory, Texas A... reduction from code-compliant residential and commercial construction is calculated to be 8.32 tons-NOx/day (15.9%), savings from retrofits to Federal buildings will be 0.81 tons-NOx/day (1.6%), savings from furnace pilot light retrofits will be 0.32 tons...

  11. Skin friction for steel piles in sand

    E-Print Network [OSTI]

    Sulaiman, Ibrahim Hikmat

    2012-06-07T23:59:59.000Z

    SkiN FRICTION FOR STEZL PIIZS IN SAND A Theeia by I. H. Sulaiman Submittei io the graduate College of t, he Texan AAB Univen-ity in Ixantial fulfil. ment of bhe zequiremenbu for the degree of NASTZR 0F SCISNCZ May 196'7 bsrjor Subject...: Civil Engineering SKIN FRICTION FOR STEEL PILES IN SAND A Thesis by I. H. Sulaiman Approved as to style and content by: Chairman of C mmittee Head of Department Memb Member 111 Skin Friction For Steel Piles in Sand (May 1967) Ibr shim Hikmat...

  12. A numerical treatment of steady, frictional boundary currents in a homogeneous ocean applied to a semi-enclosed basin

    E-Print Network [OSTI]

    Jacobs, Clifford Albert

    1967-01-01T23:59:59.000Z

    characterizing the models Page 27 Effects of pararnetcrs o" and y on reduction rate of residuals for the bottona-friction model 55 Effects of parameters o and y or reduction rate of res iduals for the lateral-friction naodcl 58 IV. Effects of parameters v.... E I Variable parameters characterizing the models Par a!net e r Description Order ? of-Magnitude Estimate Units the length ot a grid square the coefficient of botto!rI frictior the horizortal-cdd y vis cos ity 10 6 -6 10 C 111 ? 1 sec...

  13. Friction Problems in Servomechanisms: Modeling and Compensation Techniques

    E-Print Network [OSTI]

    Gravdahl, Jan Tommy

    Friction Problems in Servomechanisms: Modeling and Compensation Techniques Jan Tommy Gravdahl of this presentation Introduction Friction models 1. Static models 2. Models with time delay 3. Dynamic models Friction compensation 1. Non-model based compensation 2. Compensation based on static friction models 3

  14. Surface acidity and cumene conversion. II. A study of. gamma. -alumina containing fluoride, cobalt, and molybdenum additives: the effect of reduction

    SciTech Connect (OSTI)

    Boorman, P.M.; Kydd, R.A.; Sarbak, Z.; Somogyvari, A.

    1986-08-01T23:59:59.000Z

    The effect of reduction of the cumene conversion activity of a series of fluoride-impregnated, alumina-supported cobalt-molybdenum catalysts has been investigated. Such catalysts exhibit two different types of Broensted acid sites, one associated with the molybdenum and the other with the fluorided alumina surface. Reduction with H/sub 2/ eliminates the former type of site, but does not affect the latter. Reduction does not affect the activity of the alumina catalyst which is impregnated only with fluoride, but conversions for the other catalysts are reduced by 2-10%. In hydrocracking experiments, the dramatic influence of fluoride impregnation on cumene conversion and the synergistic nature of the fluoride and cobalt/molybdenum are demonstrated.

  15. Postulated Mesoscale Quantum of Internal Friction Hysteresis

    E-Print Network [OSTI]

    Randall D. Peters

    2004-05-27T23:59:59.000Z

    Evidence is provided, from yet another experiment, for the existence of a mesoscale quantum of internal friction hysteresis, having the value of the electron rest energy divided by the fine structure constant.

  16. Compton-Energy Scale of Friction Quantization

    E-Print Network [OSTI]

    Randall D. Peters

    2006-07-03T23:59:59.000Z

    Numerous different experiments by the author, approaching nearly two decades of study, point strongly toward the possibility that friction operates around a mesoscale quantum of energy having the value 11 pJ.

  17. Friction of Materials for Automotive Applications

    SciTech Connect (OSTI)

    Blau, Peter Julian [ORNL

    2013-01-01T23:59:59.000Z

    This brief overview of friction-related issues in materials for automobiles is invited for a special issue on automotive materials in the ASM journal AM&P. It describes a range of areas in a ground vehicle in which friction must be controlled or minimized. Applications range from piston rings to tires, and from brakes to fuel injector components. A perspective on new materials and lubricants, and the need for validation testing is presented.

  18. Friction in Forming of UD Composites

    SciTech Connect (OSTI)

    Sachs, U.; Haanappel, S. P. [Thermoplastic Composite Research Center, University of Twente, Horst building, P.O. Box 217, 7500AE Enschede (Netherlands); Akkerman, R. [Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Thermoplastic Composite Research Center, University of Twente, Horst building, P.O. Box 217, 7500AE Enschede (Netherlands); Thije, R. H. W. ten [Aniform Virtual Forming, Nieuwstraat 116, 7411 LP Deventer (Netherlands); Rooij, M. B. de [Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands)

    2011-05-04T23:59:59.000Z

    Inter-ply and tool/ply friction play a dominant role in hot stamp forming of UD fiber-reinforced thermoplastic laminates. This research treats friction measurements of a PEEK-AS4 composite system. To this end, an in-house developed friction tester is utilized to pull a laminate through two heat controlled clamping platens. The friction coefficient is determined by relating the clamp force to the pull force. The geometry of the gap between the clamping platens is monitored with micrometer accuracy. A first approach to describe the relation between the geometry and frictional behavior is undertaken by applying a standard thin-film theory for hydrodynamic lubrication. Experimental measurements showed that the thin-film theory does not entirely cover the underlying physics. Thus a second model is utilized, which employs a Leonov-model to describe the shear deformation of the matrix material, while its viscosity is described with a multi-mode Maxwell model. The combination of both models shows the potential to capture the complete frictional behavior.

  19. Ti (II) Mediated Reactions in Organic Chemistry

    E-Print Network [OSTI]

    Johnson, Jeff S.

    ' #12;Generation of Ti(II) from Ti(IV) · Bercaw accessed and characterized the first Ti'X -X Generation of Ti(II) via Reductive Alkylation · Ti(IV) converted to Ti(II) via reductive/Acetylene Functionalizations · Reductive Couplings #12;Advantages of Titanium · Titanium (IV) reagents are cheap and readily

  20. Casimir Friction I: Friction of a vacuum on a spinning dielectric

    E-Print Network [OSTI]

    Yves Pomeau; David C. Roberts

    2007-04-17T23:59:59.000Z

    We introduce the concept of Casimir friction, i.e. friction due to quantum fluctuations. In this first article we describe the calculation of a constant torque, arising from the scattering of quantum fluctuations, on a dielectric rotating in an electromagnetic vacuum.

  1. Status of Stellite 6 friction testing

    SciTech Connect (OSTI)

    Watkins, J.C.; DeWall, K.G. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Weidenhamer, G.H. [Nuclear Regulatory Commission (United States)

    1998-06-01T23:59:59.000Z

    For the past several years, researchers at the Idaho National Engineering and Environmental Laboratory, under the sponsorship of the US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, have been investigating the performance of motor-operated valves subjected to design basis flow and pressure loads. Part of this research addresses the friction that occurs at the interface between the valve disc and the valve body seats during operation of a gate valve. In most gate valves, these surfaces are hardfaced with Stellite 6, a cobalt-based alloy. Analytical methods exist for predicting the thrust needed to operate these valves at specific pressure conditions. To produce accurate valve thrust predictions, the analyst must have a reasonably accurate, though conservative, estimate of the coefficient of friction at the disc-to-seat interface. One of the questions that remains to be answered is whether, and to what extent, aging of the disc and seat surfaces effects the disc-to-seat coefficient of friction. Specifically, does the environment in a nuclear plants piping system cause the accumulation of an oxide film on these surfaces that increases the coefficient of friction; and if so, how great is the increase? This paper presents results of specimen tests addressing this issue, with emphasis on the following: (1) the characteristics and thickness of the oxide film that develops on Stellite 6 as it ages; (2) the change in the friction coefficient of Stellite 6 as it ages, including the question of whether the friction coefficient eventually reaches a plateau; and (3) the effect in-service cycling has on the characteristics and thickness of the oxide film and on the friction coefficient.

  2. Casimir Friction Force Between Polarizable Media

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2012-01-18T23:59:59.000Z

    This work is a continuation of our recent series of papers on Casimir friction, for a pair of particles of low relative particle velocity. Each particle is modeled as a simple harmonic oscillator. Our basic method, as before, is the use of quantum mechanical statistical mechanics, involving the Kubo formula, at finite temperature. In this work we begin by analyzing the Casimir friction between two particles polarizable in all spatial directions, this being a generalization of our study in EPL 91, 60003 (2010), which was restricted to a pair of particles with longitudinal polarization only. For simplicity the particles are taken to interact via the electrostatic dipole-dipole interaction. Thereafter, we consider the Casimir friction between one particle and a dielectric half-space, and also the friction between two dielectric half-spaces. Finally, we consider general polarizabilities (beyond the simple one-oscillator form), and show how friction occurs at finite temperature when finite frequency regions of the imaginary parts of polarizabilities overlap.

  3. Rubber friction: role of the flash temperature

    E-Print Network [OSTI]

    B. N. J. Persson

    2006-05-10T23:59:59.000Z

    When a rubber block is sliding on a hard rough substrate, the substrate asperities will exert time-dependent deformations of the rubber surface resulting in viscoelastic energy dissipation in the rubber, which gives a contribution to the sliding friction. Most surfaces of solids have roughness on many different length scales, and when calculating the friction force it is necessary to include the viscoelastic deformations on all length scales. The energy dissipation will result in local heating of the rubber. Since the viscoelastic properties of rubber-like materials are extremely strongly temperature dependent, it is necessary to include the local temperature increase in the analysis. At very low sliding velocity the temperature increase is negligible because of heat diffusion, but already for velocities of order 0.01 m/s the local heating may be very important. Here I study the influence of the local heating on the rubber friction, and I show that in a typical case the temperature increase results in a decrease in rubber friction with increasing sliding velocity for v > 0.01 m/s. This may result in stick-slip instabilities, and is of crucial importance in many practical applications, e.g., for the tire-road friction, and in particular for ABS-breaking systems.

  4. Enhancement of disoriented chiral condensate domains with friction

    E-Print Network [OSTI]

    A. K. Chaudhuri

    1999-04-08T23:59:59.000Z

    We investigate the effect of friction on domain formation in disoriented chiral condensate. Including a friction term, we solve the equation of motion of the linear sigma model fields, in the Hartree approximation. With boost-invariance and cylinderical symmetry, irrespective of friction, on average, we donot find any indication of domain like formation with quenched initial condition. However, with or without friction, some events can be found with large instabilities, indicating possible DCC domain formation in those events. With friction time scale during which instabilities grows increases. Correspondingly, with friction, it is possible to obtain large sized domains in some particular events.

  5. Method and device for frictional welding

    DOE Patents [OSTI]

    Peacock, H.B.

    1991-01-01T23:59:59.000Z

    A method for friction welding that produces a seal having essentially no gas porosity, comprises two rotationally symmetric, generally cylindrical members, spaced apart and coaxially aligned, that are rotated with respect to each other and brought together under high pressure. One member is preferably a generally cylindrical cannister that stores uranium within its hollow walls. The other member is preferably a generally cylindrical, hollow weld ring. An annular channel formed in the weld ring functions as an internal flash trap and is uniquely designed so that substantially all of the welding flash generated from the friction welding is directed into the channel`s recessed bottom. Also, the channel design limits distortion of the two members during the friction welding, process, further contributing to the complete seal that is obtained.

  6. Method and device for frictional welding

    DOE Patents [OSTI]

    Peacock, H.B.

    1992-10-13T23:59:59.000Z

    A method is described for friction welding that produces a seal having essentially no gas porosity, comprises two rotationally symmetric, generally cylindrical members, spaced apart and coaxially aligned, that are rotated with respect to each other and brought together under high pressure. One member is preferably a generally cylindrical canister that stores uranium within its hollow walls. The other member is preferably a generally cylindrical, hollow weld ring. An annular channel formed in the weld ring functions as an internal flash trap and is uniquely designed so that substantially all of the welding flash generated from the friction welding is directed into the channel's recessed bottom. Also, the channel design limits distortion of the two members during the friction welding process, further contributing to the complete seal that is obtained. 5 figs.

  7. Method and device for frictional welding

    DOE Patents [OSTI]

    Peacock, Harold B. (867 N. Belair Rd., Evans, GA 30809)

    1992-01-01T23:59:59.000Z

    A method for friction welding that produces a seal having essentially no gas porosity, comprises two rotationally symmetric, generally cylindrical members, spaced apart and coaxially aligned, that are rotated with respect to each other and brought together under high pressure. One member is preferably a generally cylindrical cannister that stores uranium within its hollow walls. The other member is preferably a generally cylindrical, hollow weld ring. An annular channel formed in the weld ring functions as an internal flash trap and is uniquely designed so that substantially all of the welding flash generated from the friction welding is directed into the channel's recessed bottom. Also, the channel design limits distortion of the two members during the friction welding process, further contributing to the complete seal that is obtained.

  8. Macroscopic approach to the Casimir friction force

    E-Print Network [OSTI]

    V. V. Nesterenko; A. V. Nesterenko

    2014-03-13T23:59:59.000Z

    The general formula is derived for the vacuum friction force between two parallel perfectly flat planes bounding two material media separated by a vacuum gap and moving relative to each other with a constant velocity $\\mathbf{v}$. The material media are described in the framework of macroscopic electrodynamics whereas the nonzero temperature and dissipation are taken into account by making use of the Kubo formulae from non-equilibrium statistical thermodynamics. The formula obtained provides a rigorous basis for calculation of the vacuum friction force within the quantum field theory methods in the condensed matter physics. The revealed $v$-dependence of the vacuum friction force proves to be the following: for zero temperature ($T=0$) it is proportional to $(v/c)^3$ and for $T>0$ this force is linear in $(v/c)$.

  9. Casimir friction at zero and finite temperatures

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2014-03-26T23:59:59.000Z

    The Casimir friction problem for dielectric plates that move parallel to each other is treated by assuming one of the plates to be at rest. The other performs a closed loop motion in the longitudinal direction. Therewith by use of energy dissipation the formalism becomes more manageable and transparent than in the conventional setting where uniform sliding motion is assumed from $t=-\\infty$ to $t=+\\infty$. One avoids separating off a reversible interparticle force (independent of friction) from the total force. Moreover, the cases of temperatures $T=0$ and finite $T$ are treated on the same footing. For metal plates we find the friction force to be proportional to $v^3$ at $T=0$ while at finite $T$ it is proportional to $v$ for small $v$ as found earlier. Comparisons with earlier results of Pendry (1997, 2010) and Barton (2011) are made.

  10. Friction and dilatancy in immersed granular matter

    E-Print Network [OSTI]

    Thibaut Divoux; Jean-Christophe Géminard

    2008-06-10T23:59:59.000Z

    The friction of a sliding plate on a thin immersed granular layer obeys Amonton-Coulomb law. We bring to the fore a large set of experimental results which indicate that, over a few decades of values, the effective dynamical friction-coefficient depends neither on the viscosity of the interstitial fluid nor on the size of beads in the sheared layer, which bears out the analogy with the solid-solid friction in a wide range of experimental parameters. We accurately determine the granular-layer dilatancy, which dependance on the grain size and slider velocity can be qualitatively accounted by considering the rheological behaviour of the whole slurry. However, additional results, obtained after modification of the grain surface by a chemical treatment, demonstrate that the theoretical description of the flow properties of granular matter, even immersed, requires the detailed properties of the grain surface to be taken into account.

  11. Dynamical friction in modified Newtonian dynamics

    E-Print Network [OSTI]

    C. Nipoti; L. Ciotti; J. Binney; P. Londrillo

    2008-03-31T23:59:59.000Z

    We have tested a previous analytical estimate of the dynamical friction timescale in Modified Newtonian Dynamics (MOND) with fully non-linear N-body simulations. The simulations confirm that the dynamical friction timescale is significantly shorter in MOND than in equivalent Newtonian systems, i.e. systems with the same phase-space distribution of baryons and additional dark matter. An apparent conflict between this result and the long timescales determined for bars to slow and mergers to be completed in previous N-body simulations of MOND systems is explained. The confirmation of the short dynamical-friction timescale in MOND underlines the challenge that the Fornax dwarf spheroidal poses to the viability of MOND.

  12. Negative skin friction at Keehi interchange

    E-Print Network [OSTI]

    Porwoll, Hubert

    2012-06-07T23:59:59.000Z

    is assumed to be the sum of the structural load, gt, a drag force, F'n, due to the fill within the pile group and a drag force F'n due to the negative skin friction of the soft layer. F = ()t + F'n + F"n (2. 1) where F'n is the weight of fill carried... of this method for an actual case. 2. 2. 3 Brome Brome (1969) describes the state of the practice in Sweden for the calculation of drag forces on piles due to negative skin friction. In Sweden most piles are driven to rock. The compression of the pile...

  13. High fidelity frictional models for MEMS.

    SciTech Connect (OSTI)

    Carpick, Robert W. (University of Wisconsin, Madison, WI); Reedy, Earl David, Jr.; Bitsie, Fernando; de Boer, Maarten Pieter; Corwin, Alex David; Ashurst, William Robert (Auburn University, Auburn, AL); Jones, Reese E.; Subhash, Ghatu S. (Michigan Technological Institute, Houghton, MI); Street, Mark D. (University of Wisconsin, Madison, WI); Sumali, Anton Hartono; Antoun, Bonnie R.; Starr, Michael James; Redmond, James Michael; Flater, Erin E. (University of Wisconsin, Madison, WI)

    2004-10-01T23:59:59.000Z

    The primary goals of the present study are to: (1) determine how and why MEMS-scale friction differs from friction on the macro-scale, and (2) to begin to develop a capability to perform finite element simulations of MEMS materials and components that accurately predicts response in the presence of adhesion and friction. Regarding the first goal, a newly developed nanotractor actuator was used to measure friction between molecular monolayer-coated, polysilicon surfaces. Amontons law does indeed apply over a wide range of forces. However, at low loads, which are of relevance to MEMS, there is an important adhesive contribution to the normal load that cannot be neglected. More importantly, we found that at short sliding distances, the concept of a coefficient of friction is not relevant; rather, one must invoke the notion of 'pre-sliding tangential deflections' (PSTD). Results of a simple 2-D model suggests that PSTD is a cascade of small-scale slips with a roughly constant number of contacts equilibrating the applied normal load. Regarding the second goal, an Adhesion Model and a Junction Model have been implemented in PRESTO, Sandia's transient dynamics, finite element code to enable asperity-level simulations. The Junction Model includes a tangential shear traction that opposes the relative tangential motion of contacting surfaces. An atomic force microscope (AFM)-based method was used to measure nano-scale, single asperity friction forces as a function of normal force. This data is used to determine Junction Model parameters. An illustrative simulation demonstrates the use of the Junction Model in conjunction with a mesh generated directly from an atomic force microscope (AFM) image to directly predict frictional response of a sliding asperity. Also with regards to the second goal, grid-level, homogenized models were studied. One would like to perform a finite element analysis of a MEMS component assuming nominally flat surfaces and to include the effect of roughness in such an analysis by using a homogenized contact and friction models. AFM measurements were made to determine statistical information on polysilicon surfaces with different roughnesses, and this data was used as input to a homogenized, multi-asperity contact model (the classical Greenwood and Williamson model). Extensions of the Greenwood and Williamson model are also discussed: one incorporates the effect of adhesion while the other modifies the theory so that it applies to the case of relatively few contacting asperities.

  14. IMPROVING MIX DESIGN AND CONSTRUCTION OF PERMEABLE FRICTION COURSE MIXTURES

    E-Print Network [OSTI]

    Alvarez Lugo, Allex Eduardo

    2012-02-14T23:59:59.000Z

    Permeable friction course (PFC), or new generation open-graded friction course (OGFC) mixtures, are hot mix asphalt (HMA) characterized by high total air voids (AV) content (minimum 18 %) as compared to the most commonly used dense-graded HMA...

  15. Reactivity studies of a pseudo three-coordinate vanadium(II) complex: Synthesis of terminal oxo and sulfido complexes of vanadium(IV) and S?S and Se?Se reductive bond cleavage reactions

    SciTech Connect (OSTI)

    Tran, Ba L.; Chen, Chun-Hsing; Mindiola, Daniel J. (Indiana)

    2012-02-07T23:59:59.000Z

    Terminal oxo and sulfido complexes in the form of (nacnac)V=E(Ntol{sub 2}) (nacnac = [ArNC(CH{sub 3})]{sub 2}CH{sup -}, Ar = 2,6-(CHMe{sub 2}){sub 2}C{sub 6}H{sub 3}, Ntol{sub 2} = {sup -}N(C{sub 6}H{sub 4}-4-Me), E = O (1), S (2)) were isolated from treatment of the masked three-coordinate vanadium(II) complex, (nacnac)V(Ntol{sub 2}), with C{sub 5}H{sub 5}NO and S{sub 8}, respectively. Both vanadium(IV) species, 1 and 2, have been characterized by room temperature X-band EPR spectroscopic studies, and in the case of complex 1, a single crystal molecular structure confirmed the presence of a terminal oxo moiety. Moreover, reaction of (nacnac)V(Ntol{sub 2}) with diphenyl-disulfide and diphenyl-diselenide results in the reductive cleavage of these compounds to produce the vanadium(III) complexes (nacnac)V(XPh)(Ntol{sub 2}) (X = S, (3), Se (4)). A molecular structure of the phenylsulfide complex, 3, confirmed formation of the d{sup 2} complex resulting from reductive cleavage of the S-S bond.

  16. Roles of Dry Friction in Fluctuating Motion of Adiabatic Piston

    E-Print Network [OSTI]

    Tomohiko G. Sano; Hisao Hayakawa

    2014-03-08T23:59:59.000Z

    The motion of an adiabatic piston under dry friction is investigated to clarify the roles of dry friction in non-equilibrium steady states. We clarify that dry friction can reverse the direction of the piston motion and causes a discontinuity or a cusp-like singularity for velocity distribution functions of the piston. We also show that the heat fluctuation relation is modified under dry friction.

  17. Demand Reduction

    Broader source: Energy.gov [DOE]

    Grantees may use funds to coordinate with electricity supply companies and utilities to reduce energy demands on their power systems. These demand reduction programs are usually coordinated through...

  18. Friction Stir Welding John Hinch and John Rudge

    E-Print Network [OSTI]

    Rudge, John

    Friction Stir Welding John Hinch and John Rudge September 11, 2002 1 Introduction Friction Stir Welding is an innovative technique for joining two pieces of metal. A rapidly rotating tool is pushed that a good model of friction stir welding should be able to predict - the power, the force, the temperature

  19. Enhancing Physicality in Touch Interaction with Programmable Friction

    E-Print Network [OSTI]

    Levesque, Vincent

    Enhancing Physicality in Touch Interaction with Programmable Friction Vincent Lévesque1 , Louise possibilities and outcomes when touch interactions are enhanced with variable surface friction. In a series of four studies, we first confirm that variable friction gives significant performance advantages in low

  20. Friction versus dilation revisited: Insights from theoretical and numerical models

    E-Print Network [OSTI]

    Einat, Aharonov

    Friction versus dilation revisited: Insights from theoretical and numerical models N. Makedonska,1 controlled by the frictional strength of the fault gouge, a granular layer that accumulates between the fault friction coefficient) of such granular layers is the systems resistance to dilation, a byprocess

  1. ORIGINAL PAPER Modeling of Thermal-Assisted Dislocation Friction

    E-Print Network [OSTI]

    Marks, Laurence D.

    ORIGINAL PAPER Modeling of Thermal-Assisted Dislocation Friction Y. Liao · L. D. Marks Received: 25+Business Media, LLC 2009 Abstract We generalize a model for friction at a sliding interface involving the motion of thermally activated friction. Going further, we suggest a plausible method for generalizing the fric- tional

  2. Dry friction avalanches: Experiment and theory Sergey V. Buldyrev,1

    E-Print Network [OSTI]

    Buldyrev, Sergey

    Dry friction avalanches: Experiment and theory Sergey V. Buldyrev,1 John Ferrante,2 and Fredy R and theoretical models are presented supporting the conjecture that dry friction stick-slip is described by self the variation of the friction force as a function of time. We study nominally flat surfaces of matching aluminum

  3. Friction-Induced Vibrations in Railway Transportation Chandra Prakash Sharma

    E-Print Network [OSTI]

    Phani, A. Srikantha

    Friction-Induced Vibrations in Railway Transportation by Chandra Prakash Sharma B. Tech., Sardar;Abstract Controlling friction at the wheel-rail interface is indispensable for extending track life implementation of friction modifier system consists of a stick-tube assembly, attached through a bracket which

  4. Friction and Adhesion Hysteresis between Surfactant Monolayers in Water

    E-Print Network [OSTI]

    Klein, Jacob

    Friction and Adhesion Hysteresis between Surfactant Monolayers in Water Wuge H. Briscoe Physical friction between two surfaces in adhesive contact with the loading­unloading adhesion hysteresis between them. We then examine in light of this model the observed low friction between two mica surfaces coated

  5. Analysis and Model-Based Control of Servomechanisms With Friction

    E-Print Network [OSTI]

    Papadopoulos, Evangelos

    Analysis and Model-Based Control of Servomechanisms With Friction Evangelos G. Papadopoulos e Engineering, National Technical University of Athens, 15780 Athens, Greece Friction is responsible for several, model-based feedback compensation is studied for servomechanism tracking tasks. Several kinetic friction

  6. Molecular friction and epitactic coupling between monolayers in supported bilayers

    E-Print Network [OSTI]

    Boyer, Edmond

    1535 Molecular friction and epitactic coupling between monolayers in supported bilayers R. Merkel un substrat de membrane couplée (Evans et Sackmann, 1988), on détermine la friction moléculaire coefficients de friction entre les couches en fixant la couche mononucléaire proximale sur le substrat par des

  7. Friction as an activated process Ondej Soucek, Frantisek Gallovic

    E-Print Network [OSTI]

    Cerveny, Vlastislav

    Friction as an activated process Ondej Soucek, Frantisek Gallovic Mathematical Institute University in Prague 30.11.2011 (Geodynamical seminar) Friction as an activated process 30.11.2011 1 / 19 #12 - non-smoothness of the "potentials" (Geodynamical seminar) Friction as an activated process 30

  8. ON THE IDENTIFICATION AND HAPTIC DISPLAY OF FRICTION

    E-Print Network [OSTI]

    Stanford University

    ON THE IDENTIFICATION AND HAPTIC DISPLAY OF FRICTION A DISSERTATION SUBMITTED TO THE DEPARTMENT by Christopher Richard All Rights Reserved #12;iv Abstract Although friction is an important phenomenon and greatly affects the way in which individ- uals interact with the world, friction is all but absent from

  9. Seismic Interstory Drift Demands in Steel Friction Damped Braced Buildings

    E-Print Network [OSTI]

    Peternell Altamira, Luis E.

    2010-01-16T23:59:59.000Z

    Figure 2.4: Sumitomo friction damper and installation detail (Aiken and Kelly 1990) .... 9 Figure 2.5: Slotted bolted connection of Fitzgerald (1989) and typical force- displacement loop... a superior performance of friction damped braced frames (FDBFs) using this device compared to traditional earthquake resisting systems. Figure 2.2: Friction Damper of Pall (1982) 8 In Japan, Sumitomo Metal Industries developed...

  10. Critical length limiting super-low friction

    E-Print Network [OSTI]

    Ming Ma; Andrea Benassi; Andrea Vanossi; Michael Urbakh

    2015-01-02T23:59:59.000Z

    Since the demonstration of super-low friction (superlubricity) in graphite at nanoscale, one of the main challenges in the field of nano- and micro-mechanics was to scale this phenomenon up. A key question to be addressed is to what extent superlubricity could persist, and what mechanisms could lead to its failure. Here, using an edge-driven Frenkel-Kontorova model, we establish a connection between the critical length above which superlubricity disappears and both intrinsic material properties and experimental parameters. A striking boost in dissipated energy with chain length emerges abruptly due to a high-friction stick-slip mechanism caused by deformation of the slider leading to a local commensuration with the substrate lattice. We derived a parameter-free analytical model for the critical length that is in excellent agreement with our numerical simulations. Our results provide a new perspective on friction and nano-manipulation and can serve as a theoretical basis for designing nano-devices with super-low friction, such as carbon nanotubes.

  11. Casimir Friction Force for Moving Harmonic Oscillators

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2011-11-21T23:59:59.000Z

    Casimir friction is analyzed for a pair of dielectric particles in relative motion. We first adopt a microscopic model for harmonically oscillating particles at finite temperature T moving non-relativistically with constant velocity. We use a statistical-mechanical description where time-dependent correlations are involved. This description is physical and direct, and, in spite of its simplicity, is able to elucidate the essentials of the problem. This treatment elaborates upon, and extends, an earlier theory of ours back in 1992. The energy change Delta E turns out to be finite in general, corresponding to a finite friction force. In the limit of zero temperature the formalism yields, however, Delta E ->0, this being due to our assumption about constant velocity, meaning slowly varying coupling. For couplings varying more rapidly, there will also be a finite friction force at T=0. As second part of our work, we consider the friction problem using time-dependent perturbation theory. The dissipation, basically a second order effect, is obtainable with the use of first order theory, the reason being the absence of cross terms due to uncorrelated phases of eigenstates. The third part of the present paper is to demonstrate explicitly the equivalence of our results with those recently obtained by Barton (2010); this being not a trivial task since the formal results are seemingly quite different from each other.

  12. Modelling of the Effects of Friction and Compression on Explosives ESGI80 Modelling of the Effects of Friction and

    E-Print Network [OSTI]

    Purvis, Richard

    Modelling of the Effects of Friction and Compression on Explosives ESGI80 Modelling of the Effects of Friction and Compression on Explosives Problem presented by John Curtis Atomic Weapons Establishment, based on the compression of a sample of the explosive. The study group identified frictional heating

  13. Shear Jamming in Granular Experiments without Basal Friction

    E-Print Network [OSTI]

    Hu Zheng; Joshua A. Dijksman; Robert P. Behringer

    2014-04-29T23:59:59.000Z

    Jammed states of frictional granular systems can be induced by shear strain at densities below the isostatic jamming density ($\\phi_c$). It remains unclear, however, how much friction affects this so-called shear-jamming. Friction appears in two ways in this type of experiment: friction between particles, and friction between particles and the base on which they rest. Here, we study how particle-bottom friction, or basal friction, affects shear jamming in quasi-two dimensional experiments. In order to study this issue experimentally, we apply simple shear to a disordered packing of photoelastic disks. We can tune the basal friction of the particles by immersing the particles in a density matched liquid, thus removing the normal force, hence the friction, between the particles and base. We record the overall shear stress, and particle motion, and the photoelastic response of the particles. We compare the shear response of dry and immersed samples, which enables us to determine how basal friction affects shear jamming. Our findings indicate that changing the basal friction shifts the point of shear jamming, but it does not change the basic phenomenon of shear jamming.

  14. The influence of surface topography on the forming friction of automotive aluminum sheet

    SciTech Connect (OSTI)

    Kramer, P.A. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley National Lab., CA (United States)

    1998-05-01T23:59:59.000Z

    Interest in utilizing aluminum alloys in automobiles has increased in recent years as a result of the desire to lower automobile weight and, consequently, increase fuel economy. While aluminum alloy use in cast parts has increased, outer body panel applications are still being investigated. The industry is interested in improving the formability of these sheet alloys by a combination of alloy design and processing. A different avenue of improving the formability of these alloys may be through patterning of the sheet surface. Surface patterns hold the lubricant during the forming process, with a resulting decrease in the sheet-die surface contact. While it has been speculated that an optimum surface pattern would consist of discrete cavities, detailed investigation into the reduction of forming friction by utilizing discrete patterns is lacking. A series of discrete patterns were investigated to determine the dependence of the forming friction of automotive aluminum alloys on pattern lubricant carrying capacity and on material strength. Automotive aluminum alloys used in outer body panel applications were rolled on experimental rolls that had been prepared with a variety of discrete patterns. All patterns for each alloy were characterized before and after testing both optically and, to determine pattern lubricant capacity, using three dimensional laser profilometry. A draw bead simulation (DBS) friction tester was designed and fabricated to determine the forming friction of the patterned sheets. Tensile testing and frictionless DBS testing were performed to ascertain the material properties of each sheet. The most striking result of this work was the inversely linear dependence of forming friction on the lubricant carrying capacity of the discrete patterns.

  15. EFFECT OF TOOL FEATURE ON THE JOINT STRENGTH OF DISSIMILAR FRICTION STIR LAP WELDS

    SciTech Connect (OSTI)

    Jana, Saumyadeep; Hovanski, Yuri; Grant, Glenn J.; Mattlin, Karl F.

    2011-04-25T23:59:59.000Z

    Several variations of friction stir tools were used to investigate the effects on the joint strengths of dissimilar friction stir lap welds. In the present lap weld configuration the top sheet was a 2.32 mm thick Mg (AZ 31) alloy. The bottom sheet consisted of two different steels, a (i) 0.8 mm thick electro-galvanized (EG) mild steel, or a (ii) 1.5 mm thick hot dip galvanized (HDG) high strength low alloy (HSLA) steel. Initially the tool shape was modified to accommodate the material, at which point the tool geometry was fixed. With a fixed tool geometry an additional feature was added to the pin bottom on one of the tools by incorporating a short hard insert, which would act as a stronger bottom sheet cutter. The effects of such modification on the unguided lap shear strength, and associated microstructural changes are discussed in this study.

  16. SCENARIOS FOR DEEP CARBON EMISSION REDUCTIONS FROM ELECTRICITY BY 2050 IN WESTERN NORTH AMERICA USING THE SWITCH ELECTRIC POWER SECTOR PLANNING MODEL California's Carbon Challenge Phase II Volume II

    SciTech Connect (OSTI)

    Collaboration/ University of California, Berkeley; Nelson, James; Mileva, Ana; Johnston, Josiah; Kammen, Daniel; Wei, Max; Greenblatt, Jeffrey

    2014-01-01T23:59:59.000Z

    This study used a state-of-the-art planning model called SWITCH for the electric power system to investigate the evolution of the power systems of California and western North America from present-day to 2050 in the context of deep decarbonization of the economy. Researchers concluded that drastic power system carbon emission reductions were feasible by 2050 under a wide range of possible futures. The average cost of power in 2050 would range between $149 to $232 per megawatt hour across scenarios, a 21 to 88 percent increase relative to a business-as-usual scenario, and a 38 to 115 percent increase relative to the present-day cost of power. The power system would need to undergo sweeping change to rapidly decarbonize. Between present-day and 2030 the evolution of the Western Electricity Coordinating Council power system was dominated by implementing aggressive energy efficiency measures, installing renewable energy and gas-fired generation facilities and retiring coal-fired generation. Deploying wind, solar and geothermal power in the 2040 timeframe reduced power system emissions by displacing gas-fired generation. This trend continued for wind and solar in the 2050 timeframe but was accompanied by large amounts of new storage and long-distance high-voltage transmission capacity. Electricity storage was used primarily to move solar energy from the daytime into the night to charge electric vehicles and meet demand from electrified heating. Transmission capacity over the California border increased by 40 - 220 percent by 2050, implying that transmission siting, permitting, and regional cooperation will become increasingly important. California remained a net electricity importer in all scenarios investigated. Wind and solar power were key elements in power system decarbonization in 2050 if no new nuclear capacity was built. The amount of installed gas capacity remained relatively constant between present-day and 2050, although carbon capture and sequestration was installed on some gas plants by 2050.

  17. Control of friction at the nanoscale

    DOE Patents [OSTI]

    Barhen, Jacob; Braiman, Yehuda Y.; Protopopescu, Vladimir

    2010-04-06T23:59:59.000Z

    Methods and apparatus are described for control of friction at the nanoscale. A method of controlling frictional dynamics of a plurality of particles using non-Lipschitzian control includes determining an attribute of the plurality of particles; calculating an attribute deviation by subtracting the attribute of the plurality of particles from a target attribute; calculating a non-Lipschitzian feedback control term by raising the attribute deviation to a fractionary power .xi.=(2m+1)/(2n+1) where n=1, 2, 3 . . . and m=0, 1, 2, 3 . . . , with m strictly less than n and then multiplying by a control amplitude; and imposing the non-Lipschitzian feedback control term globally on each of the plurality of particles; imposing causes a subsequent magnitude of the attribute deviation to be reduced.

  18. The effect of friction on drum brakes

    SciTech Connect (OSTI)

    Huang, Y.M.; Shyr, J.S. [National Taiwan Univ. (China)

    1995-12-31T23:59:59.000Z

    The boundary element method (BEM) has been developed for a long period of time. Cruse and Wilson developed an isoparametric quadratic element. Rizzo, Cruse, Rizzo and Shippy, and Swedlow and cruse applied the method to various problems. It shows that the BEM can provide a very good analytical result in the linear problem and it can reduce time in preparation of numerical data. Watson and Newcomb pointed out that the pressure distribution on the contact surface of the brake drum and the lining plate do not vary significantly along the axis. The deflection can be reduced by an appropriate design of the web; therefore, two dimensional analysis with the BEM is used in this analysis. Based on the authors` knowledge, this is the first paper to analyze the drum brake by using the BEM. The assumptions are the brake drum to be a rigid body, perfect interface contact between the drum and the shoe, the constant friction coefficient of the friction material and the thermal effect to be neglected. The two dimensional equations are derived based on the Somigliana`s identity. Since there is no shape function and no need of the Jacobin for the coordinate transform, to integrate numerically is easier and to write a computer code is simpler for the constant value element than the second order element. The linear element is inappropriate to treat the comer problem. Using the linear elements or second order elements creates discontinuous phenomena along the irregular boundary. The common nodal point has different normal vector and boundary conditions. It is necessary to have an extra equation to provide a unique solution for the final linear equation. Using the constant value element can get rid of this problem. The effect of the friction on the pressure distribution at the friction interface is studied. The calculated results of the pressure distribution are compared with the available data. The mathematical model can be used as a design tool to predict the performance of drum brakes.

  19. Friction- and wear-reducing coating

    DOE Patents [OSTI]

    Zhu, Dong (Farmington Hills, MI); Milner, Robert (Warren, MI); Elmoursi, Alaa AbdelAzim (Troy, MI)

    2011-10-18T23:59:59.000Z

    A coating includes a first layer of a ceramic alloy and a second layer disposed on the first layer and including carbon. The coating has a hardness of from 10 to 20 GPa and a coefficient of friction of less than or equal to 0.12. A method of coating a substrate includes cleaning the substrate, forming the first layer on the substrate, and depositing the second layer onto the first layer to thereby coat the substrate.

  20. Mutual Friction in Superfluid Neutron Stars

    E-Print Network [OSTI]

    N. Andersson; T. Sidery; G. L. Comer

    2005-10-03T23:59:59.000Z

    We discuss vortex-mediated mutual friction in the two-fluid model for superfluid neutron star cores. Our discussion is based on the general formalism developed by Carter and collaborators, which makes due distinction between transport velocity and momentum for each fluid. This is essential for an implementation of the so-called entrainment effect, whereby the flow of one fluid imparts momentum in the other and vice versa. The mutual friction follows by balancing the Magnus force that acts on the quantised neutron vortices with a resistive force due to the scattering of electrons off of the magnetic field with which each vortex core is endowed. We derive the form of the macroscopic mutual friction force which is relevant for a model based on smooth-averaging over a collection of vortices. We discuss the coefficients that enter the expression for this force, and the timescale on which the two interpenetrating fluids in a neutron star core are coupled. This discussion confirms that our new formulation accords well with previous work in this area.

  1. Friction-Induced Fluid Heating in Nanoscale Helium Flows

    SciTech Connect (OSTI)

    Li Zhigang [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2010-05-21T23:59:59.000Z

    We investigate the mechanism of friction-induced fluid heating in nanoconfinements. Molecular dynamics simulations are used to study the temperature variations of liquid helium in nanoscale Poiseuille flows. It is found that the fluid heating is dominated by different sources of friction as the external driving force is changed. For small external force, the fluid heating is mainly caused by the internal viscous friction in the fluid. When the external force is large and causes fluid slip at the surfaces of channel walls, the friction at the fluid-solid interface dominates over the internal friction in the fluid and is the major contribution to fluid heating. An asymmetric temperature gradient in the fluid is developed in the case of nonidentical walls and the general temperature gradient may change sign as the dominant heating factor changes from internal to interfacial friction with increasing external force.

  2. Dynamic recrystallization in friction surfaced austenitic stainless steel coatings

    SciTech Connect (OSTI)

    Puli, Ramesh, E-mail: rameshpuli2000@gmail.com; Janaki Ram, G.D.

    2012-12-15T23:59:59.000Z

    Friction surfacing involves complex thermo-mechanical phenomena. In this study, the nature of dynamic recrystallization in friction surfaced austenitic stainless steel AISI 316L coatings was investigated using electron backscattered diffraction and transmission electron microscopy. The results show that the alloy 316L undergoes discontinuous dynamic recrystallization under conditions of moderate Zener-Hollomon parameter during friction surfacing. - Highlights: Black-Right-Pointing-Pointer Dynamic recrystallization in alloy 316L friction surfaced coatings is examined. Black-Right-Pointing-Pointer Friction surfacing leads to discontinuous dynamic recrystallization in alloy 316L. Black-Right-Pointing-Pointer Strain rates in friction surfacing exceed 400 s{sup -1}. Black-Right-Pointing-Pointer Estimated grain size matches well with experimental observations in 316L coatings.

  3. Friction (Chapter 5, section 8) & Circular Motion (Chapter 6,

    E-Print Network [OSTI]

    1 Week 5 Friction (Chapter 5, section 8) & Circular Motion (Chapter 6, sections 1-2) Lecture Quiz 1 travels in time t is: A. x B. 1.5x C. 3x D. 4.5x E. 9x Forces of Friction When an object to the interactions between the object and its environment This resistance is called the force of friction Forces

  4. Fact or friction: Inferring rheology from nonvolcanic tremor and low-frequency earthquakes on the deep San Andreas fault

    E-Print Network [OSTI]

    Thomas, Amanda

    2012-01-01T23:59:59.000Z

    2.5 Optimal friction coefficient . . . . . . . . . . . . . .effective coefficient of friction. Values for the tremor,procedure on each friction value for each catalogue. Maximum

  5. Effective friction law for smallscale fault heterogeneity in 3D dynamic rupture

    E-Print Network [OSTI]

    Nicolas, Chamot-Rooke

    Effective friction law for smallscale fault heterogeneity in 3D dynamic rupture S. Latour,1 M friction, we numerically construct effective friction laws that integrate the effects of smallscale, the static friction heterogeneities and the friction law. We first define a periodic smallscale heterogeneous

  6. Friction Modeling for Lubricated Engine and Drivetrain Components...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Modeling for Lubricated Engine and Drivetrain Components Friction Modeling for Lubricated Engine and Drivetrain Components 2010 DOE Vehicle Technologies and Hydrogen Programs...

  7. Micro- and macroscale coefficients of friction of cementitious materials

    SciTech Connect (OSTI)

    Lomboy, Gilson [Department of Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA 50011 (United States)] [Department of Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA 50011 (United States); Sundararajan, Sriram, E-mail: srirams@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States)] [Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States); Wang, Kejin [Department of Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA 50011 (United States)] [Department of Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA 50011 (United States)

    2013-12-15T23:59:59.000Z

    Millions of metric tons of cementitious materials are produced, transported and used in construction each year. The ease or difficulty of handling cementitious materials is greatly influenced by the material friction properties. In the present study, the coefficients of friction of cementitious materials were measured at the microscale and macroscale. The materials tested were commercially-available Portland cement, Class C fly ash, and ground granulated blast furnace slag. At the microscale, the coefficient of friction was determined from the interaction forces between cementitious particles using an Atomic Force Microscope. At the macroscale, the coefficient of friction was determined from stresses on bulk cementitious materials under direct shear. The study indicated that the microscale coefficient of friction ranged from 0.020 to 0.059, and the macroscale coefficient of friction ranged from 0.56 to 0.75. The fly ash studied had the highest microscale coefficient of friction and the lowest macroscale coefficient of friction. -- Highlights: •Microscale (interparticle) coefficient of friction (COF) was determined with AFM. •Macroscale (bulk) COF was measured under direct shear. •Fly ash had the highest microscale COF and the lowest macroscale COF. •Portland cement against GGBFS had the lowest microscale COF. •Portland cement against Portland cement had the highest macroscale COF.

  8. Friction of different monolayer lubricants in MEMs interfaces.

    SciTech Connect (OSTI)

    Carpick, Robert W. (University of Wisconsin, Madison, WI); Street, Mark D. (University of Wisconsin, Madison, WI); Ashurst, William Robert (Auburn University, Auburn, AL); Corwin, Alex David

    2006-01-01T23:59:59.000Z

    This report details results from our last year of work (FY2005) on friction in MEMS as funded by the Campaign 6 program for the Microscale Friction project. We have applied different monolayers to a sensitive MEMS friction tester called the nanotractor. The nanotractor is also a useful actuator that can travel {+-}100 {micro}m in 40 nm steps, and is being considered for several MEMS applications. With this tester, we can find static and dynamic coefficients of friction. We can also quantify deviations from Amontons' and Coulomb's friction laws. Because of the huge surface-to-volume ratio at the microscale, surface properties such as adhesion and friction can dominate device performance, and therefore such deviations are important to quantify and understand. We find that static and dynamic friction depend on the monolayer lubricant applied. The friction data can be modeled with a non-zero adhesion force, which represents a deviation from Amontons' Law. Further, we show preliminary data indicating that the adhesion force depends not only on the monolayer, but also on the normal load applied. Finally, we also observe slip deflections before the transition from static to dynamic friction, and find that they depend on the monolayer.

  9. The influence of internal friction on rotordynamic instability

    E-Print Network [OSTI]

    Srinivasan, Anand

    2004-09-30T23:59:59.000Z

    and suggest that subsynchronous vibration in rotating machinery can have numerous sources or causes. Also, subsynchronous whirl due to internal friction is not a highly repeatable phenomenon....

  10. Friction in a Model of Hamiltonian Dynamics

    E-Print Network [OSTI]

    Juerg Froehlich; Zhou Gang; Avy Soffer

    2011-10-29T23:59:59.000Z

    We study the motion of a heavy tracer particle weakly coupled to a dense ideal Bose gas exhibiting Bose-Einstein condensation. In the so-called mean-field limit, the dynamics of this system approaches one determined by nonlinear Hamiltonian evolution equations describing a process of emission of Cerenkov radiation of sound waves into the Bose-Einstein condensate along the particle's trajectory. The emission of Cerenkov radiation results in a friction force with memory acting on the tracer particle and causing it to decelerate until it comes to rest.

  11. Casimir friction: Relative motion more generally

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2014-09-23T23:59:59.000Z

    This paper extends our recent study on Casimir friction forces for dielectric plates moving parallel to each other [J. S. H{\\o}ye and I. Brevik, Eur. Phys. J. D {\\bf 68}, 61 (2014)], to the case where the plates are no longer restricted to rectilinear motion. Part of the mathematical formalism thereby becomes more cumbersome, but reduces in the end to the form that we could expect to be the natural one in advance. As an example, we calculate the Casimir torque on a planar disc rotating with constant angular velocity around its vertical symmetry axis next to another plate.

  12. A Drucker-Prager model for elastic contact with friction; A Drucker-Prager model for elastic contact with friction.

    E-Print Network [OSTI]

    wu, yunxian

    2011-01-01T23:59:59.000Z

    ?? In mumerical contact simulations with friction, the simple Coloumb law is usually employed. Standard plasticity models are difficult to use since the balance enforced… (more)

  13. Nitrate reduction

    DOE Patents [OSTI]

    Dziewinski, Jacek J. (Los Alamos, NM); Marczak, Stanislaw (Los Alamos, NM)

    2000-01-01T23:59:59.000Z

    Nitrates are reduced to nitrogen gas by contacting the nitrates with a metal to reduce the nitrates to nitrites which are then contacted with an amide to produce nitrogen and carbon dioxide or acid anions which can be released to the atmosphere. Minor amounts of metal catalysts can be useful in the reduction of the nitrates to nitrites. Metal salts which are formed can be treated electrochemically to recover the metals.

  14. FRICTION AND WEAR STUDY OF DISPERSED PHASE INTERMETALLIC COMPOUNDS IN FERROUS MATRICES

    E-Print Network [OSTI]

    Riddle, R.A.

    2010-01-01T23:59:59.000Z

    rights. .j . J LBL-5771 FRICTION AND WEAR STUDY OF DISPERSEDS. THESIS) i LBL-5771 FRICTION AND WEAR STUDY OF DISPERSEDWilman, "A Theory of Friction and Wear During the Abrasion

  15. Lubricant-Friendly, Superhard and Low-Friction Coatings by Design...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Lubricant-Friendly, Superhard and Low-Friction Coatings by Design Lubricant-Friendly, Superhard and Low-Friction Coatings by Design Superhard and low-friction coatings and surface...

  16. Weak formulations and solution multiplicity of equilibrium configurations with Coulomb friction

    E-Print Network [OSTI]

    Bostan, Mihai

    Weak formulations and solution multiplicity of equilibrium configurations with Coulomb friction configurations of elastic struc- tures in contact with Coulomb friction. We obtain a variational formulation configurations with arbitrary small friction coefficients. We illustrate the result in two space dimensions

  17. Friction and the Inverted Pendulum Stabilization Problem Sue Ann Campbell

    E-Print Network [OSTI]

    Campbell, Sue Ann

    Friction and the Inverted Pendulum Stabilization Problem Sue Ann Campbell Department of Applied. Keywords: inverted pendulum, friction, feedback control, stability analysis. 1 #12;INTRODUCTION to be the cause of failure of a feedback controller to stabilize a three link inverted pendulum system [2

  18. Friction Stir Welding of Lightweight Vehicle Structures: Final Report

    SciTech Connect (OSTI)

    Sanella, M.L.

    2008-08-31T23:59:59.000Z

    The purpose of this Cooperative Research and Development Agreement (CRADA) between UTBattelle, LLC and Ford Motor Company was to establish friction stir welding (FSW) and friction stir processing as viable options for use in construction of lightweight substructures for trucks and cars, including engine cradles, suspension sub frames, instrument panel supports, and intake manifolds.

  19. Role of Friction in Materials Selection for Automotive Applications

    SciTech Connect (OSTI)

    Blau, Peter Julian [ORNL

    2013-01-01T23:59:59.000Z

    This is an invited article for a special issue of the ASM International monthly magazine that concerns "Automotive Materials and Applications." The article itself overviews frictional considerations in material selection for automobiles. It discusses implications for energy efficiency (engine friction) and safety (brakes) among other topics.

  20. Quantized friction force: Lindbladian model satisfying Ehrenfest theorems

    E-Print Network [OSTI]

    Denys I. Bondar; Renan Cabrera; Andre Campos; Herschel A. Rabitz

    2014-12-05T23:59:59.000Z

    We construct a quantum counterpart of classical friction, a dissipative force acting against the direction of motion with the magnitude proportional to particle's velocity. In particular, a Lindblad master equation is derived satisfying the appropriate dynamical relations for observables (i.e., the Ehrenfest theorems). These findings significantly advance a long search for a universal valid Lindbladian model of quantum friction.

  1. METHODS PAPER Addressing Practical Challenges of Low Friction Coefficient

    E-Print Network [OSTI]

    Sawyer, Wallace

    sensitive to the lubrication, environment, and contact conditions, and under nominally constant conditions Tribol Trans ASME 127:673­678, 2005), ``...the measurement of friction coefficient is extremely sensitive, friction coefficients range from about 0.2 to 1 for typical material pairs under standard conditions

  2. The nonlinear nature of friction Michael Urbakh1

    E-Print Network [OSTI]

    La Rosa, Andres H.

    ) and GPa (104 atmospheres) within microseconds. These are extreme conditions that cannot always be treated ........................................................................................................................................................................................................................... Tribology is the study of adhesion, friction, lubrication and wear of surfaces in relative motion areas. The development of durable and/or low-friction surfaces and thin lubricating films has become

  3. Friction coefficient of soft contact lenses: measurements and modeling

    E-Print Network [OSTI]

    Sawyer, Wallace

    , FL 32611, USA Received 12 October 2004; accepted 16 January 2005 Tribological conditions for contact elastohydrodynamic lubrication. Finally, the largest contributors to the friction force in these experiments were comfort is related to friction. The mechanical properties of hydro- gels are extremely sensitive to water

  4. Model coupling friction and adhesion for steel-concrete interfaces

    E-Print Network [OSTI]

    Boyer, Edmond

    Model coupling friction and adhesion for steel- concrete interfaces Michel Raous Laboratoire de: In this paper the interface behaviour between steel and concrete, during pull out tests, is numerically a variable friction coefficient in order to simulate the behaviour of the steel-concrete interface during

  5. Certification of a weld produced by friction stir welding

    DOE Patents [OSTI]

    Obaditch, Chris; Grant, Glenn J

    2013-10-01T23:59:59.000Z

    Methods, devices, and systems for providing certification of friction stir welds are disclosed. A sensor is used to collect information related to a friction stir weld. Data from the sensor is compared to threshold values provided by an extrinsic standard setting organizations using a certification engine. The certification engine subsequently produces a report on the certification status of the weld.

  6. E-Print Network 3.0 - asbestos-free friction lining Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    identification necessary. Off-line identification of friction is described by Armstrong 2... -feedback PD part and of an on-line friction compensation term, T f , which...

  7. E-Print Network 3.0 - avoid friction induced Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    friction induced Search Powered by Explorit Topic List Advanced Search Sample search results for: avoid friction induced Page: << < 1 2 3 4 5 > >> 1 INITIAL DEVELOPMENT OF A...

  8. Ice friction: The effects of surface roughness, structure, and hydrophobicity

    SciTech Connect (OSTI)

    Kietzig, Anne-Marie; Hatzikiriakos, Savvas G.; Englezos, Peter [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia V6T 1Z3 (Canada)

    2009-07-15T23:59:59.000Z

    The effect of surface roughness, structure, and hydrophobicity on ice friction is studied systematically over a wide range of temperature and sliding speeds using several metallic interfaces. Hydrophobicity in combination with controlled roughness at the nanoscale is achieved by femtosecond laser irradiation to mimic the lotus effect on the slider's surface. The controlled roughness significantly increases the coefficient of friction at low sliding speeds and temperatures well below the ice melting point. However, at temperatures close to the melting point and relatively higher speeds, roughness and hydrophobicity significantly decrease ice friction. This decrease in friction is mainly due to the suppression of capillary bridges in spite of the presence of surface asperities that facilitate their formation. Finally, grooves oriented in the sliding direction also significantly decrease friction in the low velocity range compared to scratches and grooves randomly distributed over a surface.

  9. Nonlocal microscopic theory of quantum friction between parallel metallic slabs

    SciTech Connect (OSTI)

    Despoja, Vito [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal, E-20018 San Sebastian, Basque Country (Spain); Department of Physics, University of Zagreb, Bijenicka 32, HR-10000 Zagreb (Croatia); Departamento de Fisica de Materiales and Centro Mixto CSIC-UPV/EHU, Facultad de Ciencias Quimicas, Universidad del Pais Vasco UPV/EHU, Apto. 1072, E-20080 San Sebastian, Basque Country (Spain); Echenique, Pedro M. [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal, E-20018 San Sebastian, Basque Country (Spain); Departamento de Fisica de Materiales and Centro Mixto CSIC-UPV/EHU, Facultad de Ciencias Quimicas, Universidad del Pais Vasco UPV/EHU, Apto. 1072, E-20080 San Sebastian, Basque Country (Spain); Sunjic, Marijan [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal, E-20018 San Sebastian, Basque Country (Spain); Department of Physics, University of Zagreb, Bijenicka 32, HR-10000 Zagreb (Croatia)

    2011-05-15T23:59:59.000Z

    We present a new derivation of the friction force between two metallic slabs moving with constant relative parallel velocity, based on T=0 quantum-field theory formalism. By including a fully nonlocal description of dynamically screened electron fluctuations in the slab, and avoiding the usual matching-condition procedure, we generalize previous expressions for the friction force, to which our results reduce in the local limit. Analyzing the friction force calculated in the two local models and in the nonlocal theory, we show that for physically relevant velocities local theories using the plasmon and Drude models of dielectric response are inappropriate to describe friction, which is due to excitation of low-energy electron-hole pairs, which are properly included in nonlocal theory. We also show that inclusion of dissipation in the nonlocal electronic response has negligible influence on friction.

  10. Frictional granular mechanics: A variational approach

    SciTech Connect (OSTI)

    Holtzman, R.; Silin, D.B.; Patzek, T.W.

    2009-10-16T23:59:59.000Z

    The mechanical properties of a cohesionless granular material are evaluated from grain-scale simulations. Intergranular interactions, including friction and sliding, are modeled by a set of contact rules based on the theories of Hertz, Mindlin, and Deresiewicz. A computer generated, three-dimensional, irregular pack of spherical grains is loaded by incremental displacement of its boundaries. Deformation is described by a sequence of static equilibrium configurations of the pack. A variational approach is employed to find the equilibrium configurations by minimizing the total work against the intergranular loads. Effective elastic moduli are evaluated from the intergranular forces and the deformation of the pack. Good agreement between the computed and measured moduli, achieved with no adjustment of material parameters, establishes the physical soundness of the proposed model.

  11. Dynamical friction force exerted on spherical bodies

    E-Print Network [OSTI]

    O. Esquivel; B. Fuchs

    2007-04-30T23:59:59.000Z

    We present a rigorous calculation of the dynamical friction force exerted on a spherical massive perturber moving through an infinite homogenous system of field stars. By calculating the shape and mass of the polarization cloud induced by the perturber in the background system, which decelerates the motion of the perturber, we recover Chandrasekhar's drag force law with a modified Coulomb logarithm. As concrete examples we calculate the drag force exerted on a Plummer sphere or a sphere with the density distribution of a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.

  12. High temperature low friction surface coating

    DOE Patents [OSTI]

    Bhushan, Bharat (Watervliet, NY)

    1980-01-01T23:59:59.000Z

    A high temperature, low friction, flexible coating for metal surfaces which are subject to rubbing contact includes a mixture of three parts graphite and one part cadmium oxide, ball milled in water for four hours, then mixed with thirty percent by weight of sodium silicate in water solution and a few drops of wetting agent. The mixture is sprayed 12-15 microns thick onto an electro-etched metal surface and air dried for thirty minutes, then baked for two hours at 65.degree. C. to remove the water and wetting agent, and baked for an additional eight hours at about 150.degree. C. to produce the optimum bond with the metal surface. The coating is afterwards burnished to a thickness of about 7-10 microns.

  13. Adaptive controller for regenerative and friction braking system

    DOE Patents [OSTI]

    Davis, R.I.

    1990-10-16T23:59:59.000Z

    A regenerative and friction braking system for a vehicle having one or more road wheels driven by an electric traction motor includes a driver responsive device for producing a brake demand signal having a magnitude corresponding to the level of braking force selected by the driver and friction and regenerative brakes operatively connected with the road wheels of the vehicle. A system according to this invention further includes control means for operating the friction and regenerative braking subsystems so that maximum brake torques sustainable by the road wheels of the vehicle without skidding or slipping will not be exceeded. 8 figs.

  14. Power-law friction in closely-packed granular materials

    E-Print Network [OSTI]

    Takahiro Hatano

    2007-05-08T23:59:59.000Z

    In order to understand the nature of friction in closely-packed granular materials, a discrete element simulation on granular layers subjected to isobaric plain shear is performed. It is found that the friction coefficient increases as the power of the shear rate, the exponent of which does not depend on the material constants. Using a nondimensional parameter that is known as the inertial number, the power-law can be cast in a generalized form so that the friction coefficients at different confining pressures collapse on the same curve. We show that the volume fraction also obeys a power-law.

  15. Adaptive controller for regenerative and friction braking system

    DOE Patents [OSTI]

    Davis, Roy I. (Ypsilanti, MI)

    1990-01-01T23:59:59.000Z

    A regenerative and friction braking system for a vehicle having one or more roadwheels driven by an electric traction motor includes a driver responsive device for producing a brake demand signal having a magnitude corresponding to the level of braking force selected by the driver and friction and regenerative brakes operatively connected with the roadwheels of the vehicle. A system according to this invention further includes control means for operating the friction and regenerative braking subsystems so that maximum brake torques sustainable by the roadwheels of the vehicle without skidding or slipping will not be exceeded.

  16. Effect of friction on disoriented chiral condensate formation

    E-Print Network [OSTI]

    A. K. Chaudhuri

    1998-09-08T23:59:59.000Z

    We have investigated the effect of friction on the DCC domain formation. We solve the Newton equation of motion for the O(4) fields, with quenched initial condition. The initial fields are randomly distributed in a Gaussian form. In one dimensional expansion, on the average, large DCC domains can not be formed. However, in some particular orbits, large instabilities may occur. This possibility also greatly diminishes with the introduction of friction. But, if the friction is large, the system may be overdamped and then, there is a possibility of large DCC domain formation in some events.

  17. The ground state problem for a quantum Hamiltonian model describing friction

    E-Print Network [OSTI]

    The ground state problem for a quantum Hamiltonian model describing friction Laurent Bruneau friction introduced in [4]. This model consists of a particle which interacts with a bosonic reservoir is violated in the case of linear friction, but satis#28;ed when the friction force is proportional

  18. Friction Observer and Compensation for Control of Robots with Joint Torque Measurement

    E-Print Network [OSTI]

    De Luca, Alessandro

    Friction Observer and Compensation for Control of Robots with Joint Torque Measurement Luc Le Tien-- In this paper we introduce a friction observer for robots with joint torque sensing (in particular for the DLR. The observer output corresponds to the low-pass filtered friction torque. It is used for friction compensation

  19. Friction dependence of shallow granular flows from discrete par-ticle simulations

    E-Print Network [OSTI]

    Al Hanbali, Ahmad

    Friction dependence of shallow granular flows from discrete par- ticle simulations Anthony Thornton relation for the macroscopic bed friction or basal roughness obtained from micro-scale discrete particle simulations of steady flows. We systematically vary the bed friction by changing the contact friction

  20. Friction, Adhesion, and Deformation: Dynamic Measurements with the Atomic Force Phil Attard

    E-Print Network [OSTI]

    Attard, Phil

    Friction, Adhesion, and Deformation: Dynamic Measurements with the Atomic Force Microscope Phil. Adhesion Sci. Technol. 16, 753­791 (2002).) Running title: Friction, Adhesion, and Deformation Abstract for the friction force microscope, quantitative measurements of friction and the ef- fect of adhesion, measurement

  1. Role of friction-induced torque in stick-slip motion J. Scheibert1,

    E-Print Network [OSTI]

    Role of friction-induced torque in stick-slip motion J. Scheibert1, and D.K. Dysthe1 1 PGP describing the kinematics of the transition from static friction to stick-slip motion of a linear elastic the precursors to frictional sliding and the periodic stick- slip motion are controlled by the amount of friction

  2. Demonstrations: blocks on planes, scales, to find coefficients of static and kinetic friction

    E-Print Network [OSTI]

    Boal, David

    Demonstrations: ·blocks on planes, scales, to find coefficients of static and kinetic friction Text: Fishbane 5-1, 5-2 Problems: 18, 21, 28, 30, 34 from Ch. 5 What's important: ·frictional forces ·coefficients of static and kinetic friction Friction Where objects move in contact with other objects, we know

  3. Hands-On and Minds-On Modeling Activities to Improve Students' Conceptions of Microscopic Friction

    E-Print Network [OSTI]

    Zollman, Dean

    Hands-On and Minds-On Modeling Activities to Improve Students' Conceptions of Microscopic Friction of microscopic friction. We will also present our investigation on the relative effectiveness of the use, it is possible to facilitate the refinement of students' ideas of microscopic friction. Keywords: friction

  4. Attractiveness of periodic orbits in parametrically forced systems with time-increasing friction

    E-Print Network [OSTI]

    Bartuccelli, Michele

    Attractiveness of periodic orbits in parametrically forced systems with time- increasing friction with time-increasing friction Michele Bartuccelli,1,a) Jonathan Deane,1,b) and Guido Gentile2,c) 1 oscillator in the presence of friction, and study numerically how time-varying friction affects the dynamics

  5. GENERALIZED NEWTON METHODS FOR THE 2DSIGNORINI CONTACT PROBLEM WITH FRICTION

    E-Print Network [OSTI]

    Kunisch, Karl

    GENERALIZED NEWTON METHODS FOR THE 2D­SIGNORINI CONTACT PROBLEM WITH FRICTION K. KUNISCH AND G. STADLER Abstract. The 2D­Signorini contact problem with Tresca and Coulomb friction is discussed in infinite-dimensional Hilbert spaces. First, the problem with given friction (Tresca friction) is considered

  6. Multiyear Program Plan: Reducing Friction and Wear in Heavy Vehicles

    SciTech Connect (OSTI)

    R.R. Fessler; G.R. Fenske

    1999-12-13T23:59:59.000Z

    As described in its multiyear program plan for 1998-2000, the Office of Heavy Vehicle Technologies (OHVT) envisions the development of a fuel-flexible, energy-efficient, near-zero-emissions, heavy-duty U.S. diesel engine technology devolving into all truck classes as a real and viable strategy for reducing energy requirements for commercial transport services and the rapidly growing multipurpose vehicle market (pickups, vans, and sport utility vehicles). Implementation of the OHVT program plan will have significant national benefits in energy savings, cleaner air, more jobs, and increased gross domestic product (GDP). Successful implementation will reduce the petroleum consumption of Class 1-8 trucks by 1.4 million barrels of oil per day by 2020 and over 1.8 million by 2030, amounting to a reduction in highway petroleum consumption of 13.2% and 18.6%, respectively. All types of regulated emissions will be reduced, that is, 20% drop in PM10 emissions (41,000 metric tons per year) by 203 0, 17% reduction in CO2 greenhouse gases (205 million metric tons per year), 7% reduction in NOx, 20% reduction in NMHC, and 30% reduction in CO. An increase of 15,000 jobs by 2020 is expected, as is an increase of $24 billion in GDP. The strategy of OHVT is to focus primarily on the diesel engine since it has numerous advantages. It has the highest efficiency of any engine today, 45% versus 30% for production gasoline engines; and it can be made more efficient at least to 55% and possibly up to 63%. It is the engine of choice for heavy vehicles (trucks), because it offers power, efficiency, durability, and reliability and is used extensively in rail, marine, and off-road applications. Its emission can be ultra-low to near zero, and the production infrastructure is already in place. The primary goals of OHVT are as follows: (1) Develop by 2002 the diesel-engine enabling technologies to support large-scale industry dieselization of light trucks, achieving a 35% fuel efficiency improvement over equivalent gasoline-fueled trucks. (2) Develop by 2004 the enabling technology for a Class 7-8 truck with a fuel efficiency of 10 mpg (at 65 mph) that will meet prevailing emission standards, using either diesel or a liquid alternative fuel. (3) Develop by 2006 diesel engines with fuel flexibility and a thermal efficiency of 55% with liquid alternative fuels, and a thermal efficiency of 55% with dedicated gaseous fuels. (4) Develop a methodology for analyzing and evaluating the operation of a heavy vehicle as an integrated system, considering such factors as engine efficiency; emissions; rolling resistance; aerodynamic drag; friction, wear, and lubrication effects; auxiliary power units; material substitutions for reducing weight; and other sources of parasitic energy losses. Overarching these considerations is the need to preserve system functionality, cost, competitiveness, reliability, durability, and safety.

  7. Friction Modeling and Compensation for an Industrial Robot

    E-Print Network [OSTI]

    Friction Modeling and Compensation for an Industrial Robot Stephen M. Phillips and Kevin R. Ballou it is assumed to be unpredictable or insignificant. In experiments on the PUMA 560 robot arm, Armstrong' dem

  8. Friction and Wear Enhancement of Titanium Alloy Engine Components...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    1 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation pm007blau2011o.pdf More Documents & Publications Friction and...

  9. Friction Stir Spot Welding of Advanced High Strength Steels ...

    Energy Savers [EERE]

    Stir Spot Welding of Advanced High Strength Steels (AHSS) Friction Stir Spot Welding of Advanced High Strength Steels (AHSS) Presentation from the U.S. DOE Office of Vehicle...

  10. On the friction coefficient of straight-chain aggregates

    E-Print Network [OSTI]

    Lorenzo Isella; Yannis Drossinos

    2010-07-16T23:59:59.000Z

    A methodology to calculate the friction coefficient of an aggregate in the continuum regime is proposed. The friction coefficient and the monomer shielding factors, aggregate-average or individual, are related to the molecule-aggregate collision rate that is obtained from the molecular diffusion equation with an absorbing boundary condition on the aggregate surface. Calculated friction coefficients of straight chains are in very good agreement with previous results, suggesting that the friction coefficients may be accurately calculated from the product of the collision rate and an average momentum transfer,the latter being independent of aggregate morphology. Langevin-dynamics simulations show that the diffusive motion of straight-chain aggregates may be described either by a monomer-dependent or an aggregate-average random force, if the shielding factors are appropriately chosen.

  11. Friction anisotropy: A unique and intrinsic property of decagonal quasicrystals

    SciTech Connect (OSTI)

    Park, J. Y.; Ogletree, D.; Salmeron, M.

    2008-05-01T23:59:59.000Z

    We show that friction anisotropy is an intrinsic property of the atomic structure of Al-Ni-Co decagonal quasicrystals and not only of clean and well-ordered surfaces that can be prepared in vacuum [J.Y. Park et al., Science309, 1354 (2005)]. Friction anisotropy is manifested in both nanometer-size contacts obtained with sharp atomic force microscope tips and macroscopic contacts produced in pin-on-disk tribometers. We show that the friction anisotropy, which is not observed when an amorphous oxide film covers the surface, is recovered when the film is removed due to wear. Equally important is the loss of the friction anisotropy when the quasicrystalline order is destroyed due to cumulative wear. These results reveal the intimate connection between the mechanical properties of these materials and their peculiar atomic structure.

  12. Rolling friction for hard cylinder and sphere on viscoelastic solid

    E-Print Network [OSTI]

    B. N. J. Persson

    2010-08-26T23:59:59.000Z

    We calculate the friction force acting on a hard cylinder or spherical ball rolling on a flat surface of a viscoelastic solid. The rolling friction coefficient depends non-linearly on the normal load and the rolling velocity. For a cylinder rolling on a viscoelastic solid characterized by a single relaxation time Hunter has obtained an exact result for the rolling friction, and our result is in very good agreement with his result for this limiting case. The theoretical results are also in good agreement with experiments of Greenwood and Tabor. We suggest that measurements of rolling friction over a wide range of rolling velocities and temperatures may constitute an useful way to determine the viscoelastic modulus of rubber-like materials.

  13. Frictional properties of faults: from observation on the

    E-Print Network [OSTI]

    Winfree, Erik

    Frictional properties of faults: from observation on the Longitudinal Valley Fault, Taiwan myself lucky to do what I love and to wake up every day, happy and excited about the day to come

  14. Friction Stir and Ultrasonic Solid State Joining of Magnesium...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Ultrasonic Solid State Joining of Magnesium to Steel Friction Stir and Ultrasonic Solid State Joining of Magnesium to Steel 2012 DOE Hydrogen and Fuel Cells Program and Vehicle...

  15. A laboratory study of the friction behavior of granular materials

    E-Print Network [OSTI]

    Frye, Kevin M. (Kevin Michael), 1972-

    2002-01-01T23:59:59.000Z

    I report on laboratory experiments designed to investigate the microphysical processes that result in rate- and state-dependent friction behavior and experiments designed to match the boundary conditions used by numerical ...

  16. Small mass asymptotic for the motion with vanishing friction

    E-Print Network [OSTI]

    Mark Freidlin; Wenqing Hu; Alexander Wentzell

    2012-01-05T23:59:59.000Z

    We consider the small mass asymptotic (Smoluchowski-Kramers approximation) for the Langevin equation with a variable friction coefficient. The friction coefficient is assumed to be vanishing within certain region. We introduce a regularization for this problem and study the limiting motion for the 1-dimensional case and a multidimensional model problem. The limiting motion is a Markov process on a projected space. We specify the generator and boundary condition of this limiting Markov process and prove the convergence.

  17. Yield criteria for quasibrittle and frictional materials

    E-Print Network [OSTI]

    Davide Bigoni; Andrea Piccolroaz

    2010-10-09T23:59:59.000Z

    A new yield/damage function is proposed for modelling the inelastic behaviour of a broad class of pressure-sensitive, frictional, ductile and brittle-cohesive materials. The yield function allows the possibility of describing a transition between the shape of a yield surface typical of a class of materials to that typical of another class of materals. This is a fundamental key to model the behaviour of materials which become cohesive during hardening (so that the shape of the yield surface evolves from that typical of a granular material to that typical of a dense material), or which decrease cohesion due to damage accumulation. The proposed yield function is shown to agree with a variety of experimental data relative to soil, concrete, rock, metallic and composite powders, metallic foams, porous metals, and polymers. The yield function represents a single, convex and smooth surface in stress space approaching as limit situations well-known criteria and the extreme limits of convexity in the deviatoric plane. The yield function is therefore a generalization of several criteria, including von Mises, Drucker-Prager, Tresca, modified Tresca, Coulomb-Mohr, modified Cam-clay, and --concerning the deviatoric section-- Rankine and Ottosen. Convexity of the function is proved by developing two general propositions relating convexity of the yield surface to convexity of the corresponding function. These propositions are general and therefore may be employed to generate other convex yield functions.

  18. Drag reduction in coal log pipelines

    SciTech Connect (OSTI)

    Marrero, T.R.; Liu, H. [Univ. of Missouri, Columbia, MO (United States). Capsule Pipeline Research Center

    1996-12-31T23:59:59.000Z

    It is well-known that solutions of dissolved long-chain macromolecules produce lower friction or drag losses than with the solvent alone. In coal log pipeline (CLP), water is the conveying medium. Synthetic polymers such as poly(ethylene oxide) have been dissolved in water and tested for their extent of drag reduction as a function of concentration and other variables. Lab-scale experimental results for CLP indicate substantial drag reduction at low concentration levels of polymer. But, the macromolecules exhibit degradation under mechanical shear stresses. The large molecules break into smaller units. This degradation effect causes a loss of drag reduction. However, high levels of drag reduction can be maintained as follows: (1) by injecting polymer into the CLP at several locations along the pipeline, (2) by injecting polymer of different particle sizes, (3) by using more robust types of polymers, or (4) by using polymer-fiber mixtures. This report presents the value of drag-reducing agents in terms of pumping power net cost savings. In addition, this report outlines the environmental impact of drag reduction polymers, and end-of-pipeline water treatment processes. For an operating CLP, hundreds of miles in length, the use of poly(ethylene oxide) as a drag reducing agent provides significant pumping power cost savings at a minimal materials cost.

  19. Energy Efficiency/Renewable Energy Impact in the Texas Emissions Reduction Plan (TERP), Volume II – Technical Report, Annual Report to the Texas Commission on Environmental Quality September 2002 – August 2003

    E-Print Network [OSTI]

    Haberl, J. S.; Culp, C.; Yazdani, B.; Fitzpatrick, T.; Bryant, J.; Turner, W. D.

    2003-01-01T23:59:59.000Z

    The Energy Systems Laboratory (Laboratory) is pleased to provide our second annual report, Energy Efficiency/Renewable Energy Impact in the Texas Emissions Reduction Plan to the Texas Council on Environmental Quality (TCEQ) in fulfillment of its...

  20. Energy-Dependence of Nucleus-Nucleus Potential and Friction Parameter in Fusion Reactions

    E-Print Network [OSTI]

    Kai Wen; Fumihiko Sakata; Zhu-Xia Li; Xi-Zhen Wu; Ying-Xun Zhang; Shan-Gui Zhou

    2014-11-08T23:59:59.000Z

    Applying a macroscopic reduction procedure on the improved quantum molecular dynamics (ImQMD) model, the energy dependences of the nucleus-nucleus potential, the friction parameter, and the random force characterizing a one-dimensional Langevin-type description of the heavy-ion fusion process are investigated. Systematic calculations with the ImQMD model show that the fluctuation-dissipation relation found in the symmetric head-on fusion reactions at energies just above the Coulomb barrier fades out when the incident energy increases. It turns out that this dynamical change with increasing incident energy is caused by a specific behavior of the friction parameter which directly depends on the microscopic dynamical process, i.e., on how the collective energy of the relative motion is transferred into the intrinsic excitation energy. It is shown microscopically that the energy dissipation in the fusion process is governed by two mechanisms: One is caused by the nucleon exchanges between two fusing nuclei, and the other is due to a rearrangement of nucleons in the intrinsic system. The former mechanism monotonically increases the dissipative energy and shows a weak dependence on the incident energy, while the latter depends on both the relative distance between two fusing nuclei and the incident energy. It is shown that the latter mechanism is responsible for the energy dependence of the fusion potential and explains the fading out of the fluctuation-dissipation relation.

  1. Superhydrophobic Friction Reduction Microtextured Surfaces Tae Jin KIM, Carlos H. HIDROVO

    E-Print Network [OSTI]

    Hidrovo, Carlos H.

    of microfluidic channels with different substrate surface topographies. Two different types of silicon substrates surfaces to self cleaning features on solar energy panels. Superhydrophobicity is mainly achieved

  2. A Fresh Approach to Flow Turbulence Towards Reduction of Skin-friction Drag

    E-Print Network [OSTI]

    a major contributor to carbon emissions. Ever-growing strain on the global oil supply chain and stringent million tonnes in CO2 emissions annually as per current projections. Similar estimates for the shipping energy expenditure sector, accounting for 30% of global consumption. Consequently, this sector is also

  3. Friction and Wear Reduction in Diesel Engine Valve Trains | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-UpHeatMulti-Dimensional Electrical Resistivity StructureDepartment of Energy

  4. REDUCTION CAPACITY OF SALTSTONE AND SALTSTONE COMPONENTS

    SciTech Connect (OSTI)

    Roberts, K.; Kaplan, D.

    2009-11-30T23:59:59.000Z

    The duration that saltstone retains its ability to immobilize some key radionuclides, such as technetium (Tc), plutonium (Pu), and neptunium (Np), depends on its capacity to maintain a low redox status (or low oxidation state). The reduction capacity is a measure of the mass of reductants present in the saltstone; the reductants are the active ingredients that immobilize Tc, Pu, and Np. Once reductants are exhausted, the saltstone loses its ability to immobilize these radionuclides. The reduction capacity values reported here are based on the Ce(IV)/Fe(II) system. The Portland cement (198 {micro}eq/g) and especially the fly ash (299 {micro}eq/g) had a measurable amount of reduction capacity, but the blast furnace slag (820 {micro}eq/g) not surprisingly accounted for most of the reduction capacity. The blast furnace slag contains ferrous iron and sulfides which are strong reducing and precipitating species for a large number of solids. Three saltstone samples containing 45% slag or one sample containing 90% slag had essentially the same reduction capacity as pure slag. There appears to be some critical concentration between 10% and 45% slag in the Saltstone formulation that is needed to create the maximum reduction capacity. Values from this work supported those previously reported, namely that the reduction capacity of SRS saltstone is about 820 {micro}eq/g; this value is recommended for estimating the longevity that the Saltstone Disposal Facility will retain its ability to immobilize radionuclides.

  5. A Century of Solar Ca ii Measurements and Their Implication for Solar UV Driving of Climate

    E-Print Network [OSTI]

    2009-01-01T23:59:59.000Z

    009-9330-0 A Century of Solar Ca II Measurements and Theirstrong resonance line of Ca II (K line) provide the longestrecent reductions of the Ca II K spectroheliograms obtained

  6. Mechanical and metallurgical properties of MMC friction welds

    SciTech Connect (OSTI)

    Li, Z.; Maldonado, C.; North, T.H. [Univ. of Toronto, Ontario (Canada). Dept. of Metallurgy and Materials Science; Altshuller, B. [Alcan R and D Labs., Kingston, Ontario (Canada)

    1997-09-01T23:59:59.000Z

    The mechanical and metallurgical properties of similar and dissimilar welds involving aluminum-based metal matrix composite (MMC) base material were investigated using factorial experimentation. The test materials comprised aluminum-based alloy 6061/Al{sub 2}O{sub 3} (W6A.10A-T6), aluminum Alloy 6061-T6 and AISI 304 stainless steel. Notch tensile strength increased when high friction pressures were employed during MMC/MMC, MMC/Alloy 6061, MMC/AISI 304 stainless steel and Alloy 6061/Alloy 6061 friction welding. In MMC/Alloy 6061 welds, notch tensile strength also increased when high forging pressures were employed. Applied oxide films on both the MMC and AISI stainless steel substrates had a markedly detrimental effect on dissimilar weld mechanical properties. The optimum notch tensile strength properties were produced when high friction pressure values were applied during dissimilar MMC/AISI 304 stainless steel welding. High friction pressure had two beneficial effects, i.e., it decreased the thickness of the FeAl{sub 3} intermetallic film and it promoted disruption and dispersal of oxide films at the joint interface. In direct contrast, the presence of thick anodized oxide films on the MMC substrate surface prior to friction welding had no observable influence on MMC/MMC weld mechanical properties.

  7. Non-equilibrium phase transition in an exactly solvable driven Ising model with friction

    E-Print Network [OSTI]

    Alfred Hucht

    2009-09-02T23:59:59.000Z

    A driven Ising model with friction due to magnetic correlations has recently been proposed by Kadau et al. (Phys. Rev. Lett. 101, 137205 (2008)). The non-equilibrium phase transition present in this system is investigated in detail using analytical methods as well as Monte Carlo simulations. In the limit of high driving velocities $v$ the model shows mean field behavior due to dimensional reduction and can be solved exactly for various geometries. The simulations are performed with three different single spin flip rates: the common Metropolis and Glauber rates as well as a multiplicative rate. Due to the non-equilibrium nature of the model all rates lead to different critical temperatures at $v>0$, while the exact solution matches the multiplicative rate. Finally, the cross-over from Ising to mean field behavior as function of velocity and system size is analysed in one and two dimensions.

  8. The Schroedinger equation with friction from the quantum trajectory perspective

    SciTech Connect (OSTI)

    Garashchuk, Sophya; Dixit, Vaibhav; Gu Bing; Mazzuca, James [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208 (United States)

    2013-02-07T23:59:59.000Z

    Similarity of equations of motion for the classical and quantum trajectories is used to introduce a friction term dependent on the wavefunction phase into the time-dependent Schroedinger equation. The term describes irreversible energy loss by the quantum system. The force of friction is proportional to the velocity of a quantum trajectory. The resulting Schroedinger equation is nonlinear, conserves wavefunction normalization, and evolves an arbitrary wavefunction into the ground state of the system (of appropriate symmetry if applicable). Decrease in energy is proportional to the average kinetic energy of the quantum trajectory ensemble. Dynamics in the high friction regime is suitable for simple models of reactions proceeding with energy transfer from the system to the environment. Examples of dynamics are given for single and symmetric and asymmetric double well potentials.

  9. Irreversible work and inner friction in quantum thermodynamic processes

    E-Print Network [OSTI]

    F. Plastina; A. Alecce; T. J. G. Apollaro; G. Falcone; G. Francica; F. Galve; N. Lo Gullo; R. Zambrini

    2014-07-13T23:59:59.000Z

    We discuss the thermodynamics of closed quantum systems driven out of equilibrium by a change in a control parameter and undergoing a unitary process. We compare the work actually done on the system with the one that would be performed along ideal adiabatic and isothermal transformations. The comparison with the latter leads to the introduction of irreversible work, while that with the former leads to the introduction of inner friction. We show that these two quantities can be treated on equal footing, as both can be linked with the heat exchanged in thermalization processes and both can be expressed as relative entropies. Furthermore, we show that a specific fluctuation relation for the entropy production associated with the inner friction exists, which allows the inner friction to be written in terms of its cumulants.

  10. Friction and Wear Behavior of Ultrahigh Molecular Weight Polyethylene as a Function of Crystallinity in the Presence of the

    E-Print Network [OSTI]

    Lin, Zhiqun

    Friction and Wear Behavior of Ultrahigh Molecular Weight Polyethylene as a Function: In this study, the friction and wear behavior of ultrahigh molecular weight polyethylene (UHMWPE) were evaluated Words: ultrahigh molecular weight polyethylene (UHMWPE), crystallinity, friction, wear, phospholipid

  11. Effects of mechanical properties and surface friction on elasto-plastic sliding contact

    E-Print Network [OSTI]

    Suresh, Subra

    Effects of mechanical properties and surface friction on elasto-plastic sliding contact S and many recent computational studies have established quantitative relationships between elasto-plastic systematically quantified the effect of the plastic deformation characteristics on the frictional sliding

  12. Usage of Friction-damped Braced Frames for Seismic Vibration Control

    E-Print Network [OSTI]

    Fink, Brynnan 1992-

    2012-04-16T23:59:59.000Z

    This study presents the results of experimental work that examines the functionality of friction-damped braced frames during seismic events. The simplicity and efficacy of this friction device as a means of passive vibration control suggest...

  13. Effects of the Exposure to Corrosive Salts on the Frictional Behavior of Gray Cast Iron and a Titanium-Based Metal Matrix Composite

    SciTech Connect (OSTI)

    Blau, Peter Julian [ORNL; Truhan, Jr., John J [ORNL; Kenik, Edward A [ORNL

    2007-01-01T23:59:59.000Z

    The introduction of increasingly aggressive road-deicing chemicals has created significant and costly corrosion problems for the trucking industry. From a tribological perspective, corrosion of the sliding surfaces of brakes after exposure to road salts can create oxide scales on the surfaces that affect friction. This paper describes experiments on the effects of exposure to sodium chloride and magnesium chloride sprays on the transient frictional behavior of cast iron and a titanium-based composite sliding against a commercial brake lining material. Corrosion scales on cast iron initially act as abrasive third-bodies, then they become crushed, spread out, and behave as a solid lubricant. The composition and subsurface microstructures of the corrosion products on the cast iron were analyzed. Owing to its greater corrosion resistance, the titanium composite remained scale-free and its frictional response was markedly different. No corrosion scales were formed on the titanium composite after aggressive exposure to salts; however, a reduction in friction was still observed. Unlike the crystalline sodium chloride deposits that tended to remain dry, hygroscopic magnesium chloride deposits absorbed ambient moisture from the air, liquefied, and retained a persistent lubricating effect on the titanium surfaces.

  14. Computational Investigation of Hardness Evolution During Friction-Stir Welding of AA5083 and AA2139

    E-Print Network [OSTI]

    Grujicic, Mica

    Computational Investigation of Hardness Evolution During Friction-Stir Welding of AA5083 and AA2139 coupled thermo-mechanical finite-element analysis of the friction-stir welding (FSW) process developed, finite-element analysis, friction- stir welding, hardness prediction 1. Introduction Having a more mobile

  15. Friction Stir Welding of Hydrided Titanium Alloys Mark Taylor, D.P. Field

    E-Print Network [OSTI]

    Collins, Gary S.

    Friction Stir Welding of Hydrided Titanium Alloys Mark Taylor, D.P. Field Multi-Scale Engineering for Undergraduates program under grant number EEC-0754370 During Friction Stir Welding (FSW), a non-consumable tool-state welding process, much frictional heating and force is required of the tool. This steep demand on the tool

  16. Friction and Heat Transfer Characteristics of Silica and CNT Nanofluids in a Tube Flow

    E-Print Network [OSTI]

    Kostic, Milivoje M.

    Friction and Heat Transfer Characteristics of Silica and CNT Nanofluids in a Tube Flow MILIVOJE M@niu.edu * www.kostic.niu.edu Abstract: - An apparatus for exploring friction and heat transfer characteristics flow. Initial turbulent friction and heat transfer measurements for silica and carbon nanotube (CNT

  17. An accurate elasto-plastic frictional tangential forcedisplacement model for granular-flow

    E-Print Network [OSTI]

    Vu-Quoc, Loc

    An accurate elasto-plastic frictional tangential force­displacement model for granular for both elastic and plastic deformations together with interfacial friction occurring in collisions of spherical particles. This elasto-plastic frictional TFD model, with its force-driven version presented in [L

  18. Friction and curvature judgement Chris Christou (1) and Alan Wing (2)

    E-Print Network [OSTI]

    Friction and curvature judgement Chris Christou (1) and Alan Wing (2) (1) Optometry resistance to motion due to friction. This resistance creates a force vector which varies in direction with friction. But the vector also varies in direction with the curvature of the surface traversed by the finger

  19. Friction experiments with elastography: the slow slip and the super-shear regimes

    E-Print Network [OSTI]

    Boyer, Edmond

    Friction experiments with elastography: the slow slip and the super-shear regimes S. Cathelinea , S technique derived from elastography, is used to follow the dynamic of the interface failure in a friction by Amontons in 1699 [1], the resistance to slip of an interface can be modeled by two main frictional states

  20. M.-T. DO, P. MARSAC, Y. DELANNE Prediction of Tire/Wet Road Friction from

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    M.-T. DO, P. MARSAC, Y. DELANNE 1 Prediction of Tire/Wet Road Friction from Road Surface, validation of a contact model for the prediction of low-speed friction from road surface microtexture the friction ­ speed curve from road- and tire measurable parameters. The model development is briefly

  1. Dry friction between laser-patterned surfaces: Role of alignment, structural wavelength and

    E-Print Network [OSTI]

    Mueser, Martin

    1 Dry friction between laser-patterned surfaces: Role of alignment, structural wavelength.gachot@mx.uni-saarland.de Abstract The ability to tune friction by tailoring surface topographies at micron length scales friction between laser-textured surfaces. Line-like laser patterns with varying structural wavelengths

  2. Dynamic Friction Models for Longitudinal Road/Tire Interaction: Experimental Results

    E-Print Network [OSTI]

    Tsiotras, Panagiotis

    Dynamic Friction Models for Longitudinal Road/Tire Interaction: Experimental Results C. Canudas dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles is val- idated via experiments with an actual passenger vehicle. Contrary to common static friction/slip maps

  3. Collective friction coefficients in the relaxation time approximation F. A. Ivanyuk

    E-Print Network [OSTI]

    Pomorski, Krzysztof

    Collective friction coefficients in the relaxation time approximation F. A. Ivanyuk Institute components of the friction coefficient for various single-particle potentials and have found that the nondiagonal component of the friction coefficient depends generally on the diffuseness of the potential

  4. Brownian dynamics algorithm for bead-rod semiflexible chain with anisotropic friction

    E-Print Network [OSTI]

    Natelson, Douglas

    Brownian dynamics algorithm for bead-rod semiflexible chain with anisotropic friction Alberto of semiflexible bead-rod chain with anisotropic friction can mimic closely the hydrodynamics of a slender filament dependent anisotropic bead friction coefficients. The algorithm is an extension of that given previously

  5. Long Term Friction: from Stick-Slip to Stable Sliding1 Christophe Voisin1

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Long Term Friction: from Stick-Slip to Stable Sliding1 Christophe Voisin1 , François Renard1 Abstract. We have devised an original laboratory experiment where we investigate6 the frictional behaviour, salt, an analogue for natural8 faults, allows for frictional processes plastic deformation and pressure

  6. A parallel and multiscale strategy for the parametric study of transient dynamic problems with friction

    E-Print Network [OSTI]

    with friction P.-A. Boucard1, D. Odi`evre1 and F. Gatuingt1 LMT-Cachan (ENS Cachan/CNRS/Universit´e Paris 6/PRES with friction. Our approach is based on the multiscale LATIN method with domain decomposition. This is a mixed; transient dynamics; domain decomposition; contact; friction; parallel processing 1. INTRODUCTION Modeling

  7. Analysis of a unilateral contact problem taking into account adhesion and friction

    E-Print Network [OSTI]

    Rossi, Riccarda

    Analysis of a unilateral contact problem taking into account adhesion and friction Elena Bonetti) adhesion and of the friction are taken into account. We describe the adhesion phenomenon in terms conditions, and friction by a nonlocal Coulomb law. All the constraints on the internal variables as well

  8. Noise and vibration for a self-excited mechanical system with friction

    E-Print Network [OSTI]

    Boyer, Edmond

    Noise and vibration for a self-excited mechanical system with friction K. Soobbarayen1,a , S. The contact is modelled by introducing several local contact elements at the friction interface and a cubic contact law is used to describe the contact force. The classical Coulomb law is applied to model friction

  9. Creeping Friction Dynamics and Molecular Dissipation Mechanisms in Glassy Polymers Scott Sills and Rene M. Overney

    E-Print Network [OSTI]

    Creeping Friction Dynamics and Molecular Dissipation Mechanisms in Glassy Polymers Scott Sills kinetic friction between an atomic force microscopy tip and a surface of amorphous glassy polystyrene has of the friction results using the method of reduced variables revealed the dissipative behavior as an activated

  10. Long term friction: From stick-slip to stable sliding Christophe Voisin,1

    E-Print Network [OSTI]

    Long term friction: From stick-slip to stable sliding Christophe Voisin,1 Franc¸ois Renard,1 July 2007. [1] We have devised an original laboratory experiment where we investigate the frictional properties, salt, an analogue for natural faults, allows for frictional processes plastic deformation

  11. Analysis of a unilateral contact problem taking into account adhesion and friction

    E-Print Network [OSTI]

    Rossi, Riccarda

    Analysis of a unilateral contact problem taking into account adhesion and friction Elena Bonetti) adhesion and of the friction are taken into account. We describe the adhesion phenomenon in terms conditions and the friction by a nonlocal Coulomb law. All the constraints on the internal variables as well

  12. Long Term Friction: from Stick-Slip to Stable Sliding Christophe Voisin1

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Long Term Friction: from Stick-Slip to Stable Sliding Christophe Voisin1 , François Renard1 where we investigate the frictional behaviour of a single crystal salt slider over a large number for friction and plastic deformation and pressure solution creep to be efficient on the same timescale. During

  13. Internal Friction Controls the Speed of Protein Folding from a Compact Configuration

    E-Print Network [OSTI]

    Roder, Heinrich

    Internal Friction Controls the Speed of Protein Folding from a Compact Configuration Suzette A is independent of the cosolutes used to adjust solvent friction. Therefore, interactions within the interior. Interestingly, we find a very strong temperature dependence in these "internal friction"-controlled dynamics

  14. Friction of partially embedded vertically aligned carbon nanofibers inside Burak Aksak and Metin Sittia

    E-Print Network [OSTI]

    Goldstein, Seth Copen

    Friction of partially embedded vertically aligned carbon nanofibers inside elastomers Burak Aksak partially embedded inside polyurethane eVACNFs are proposed as a robust high friction fibrillar material and selective oxygen plasma etching, fibers are partially released up to 5 m length. Macroscale friction

  15. Friction in Mid-latitude Bob Plant, Stephen Belcher, Bob Beare, Andy Brown

    E-Print Network [OSTI]

    Plant, Robert

    Friction in Mid-latitude Cyclones Ian Boutle Bob Plant, Stephen Belcher, Bob Beare, Andy Brown #12;Motivation · Many studies have shown the significance of friction in formation and dissipation of cyclones Dt = + � . F . Diabatic Term: · Surface heat fluxes · Latent heat fluxes Frictional Term

  16. FRICTION AND THE INVERTED PENDULUM STABILIZATION PROBLEM Sue Ann Campbell Stephanie Crawford Kirsten Morris

    E-Print Network [OSTI]

    Morris, Kirsten

    FRICTION AND THE INVERTED PENDULUM STABILIZATION PROBLEM Sue Ann Campbell Stephanie Crawford of friction on the design and performance of feedback controllers that aim to stabilize the pendulum in the upright position. We show that a controller designed using a simple viscous friction model has poor

  17. Journal of Sound and Vibration (1997) 202(2), 203218 SEMI-ACTIVE CONTROL OF FRICTION

    E-Print Network [OSTI]

    Dupont, Pierre

    Journal of Sound and Vibration (1997) 202(2), 203­218 SEMI-ACTIVE CONTROL OF FRICTION DAMPERS P, U.S.A. (Received 22 January 1996, and in final form 21 October 1996) Semi-active control of friction dampers has been proposed to improve the energy dissipation characteristics of passive friction dampers

  18. Dynamic Friction Models for Longitudinal Road/Tire Interaction: Theoretical Advances

    E-Print Network [OSTI]

    Tsiotras, Panagiotis

    Dynamic Friction Models for Longitudinal Road/Tire Interaction: Theoretical Advances C. Canudas we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled-point friction problems, called the LuGre model [1]. By assuming a con- tact patch between the tire

  19. Adaptive Friction Compensation for Servo J. Wang, S. S. Ge, and T. H. Lee

    E-Print Network [OSTI]

    Ge, Shuzhi Sam

    Adaptive Friction Compensation for Servo Mechanisms J. Wang, S. S. Ge, and T. H. Lee Department@nus.edu.sg Abstract Friction exists in all machines having relative motion, and plays an important role in many servo, accurate friction modeling and effective compensation techniques have to be investigated. In this chapter

  20. Nonlinear friction of a damped dimer sliding on a periodic substrate S. Gonalves,1,2,

    E-Print Network [OSTI]

    Kenkre, V.M.

    Nonlinear friction of a damped dimer sliding on a periodic substrate S. Gonçalves,1,2, * V. M, USA (Received 23 July 2004; published 12 November 2004) The nonlinear sliding friction of a dimer over that the friction force has an approximate v-3 depen- dence if the velocity is sufficiently large

  1. DISPLAY OF FRICTION IN VIRTUAL ENVIRONMENTS BASED ON HUMAN FINGER PAD CHARACTERISTICS

    E-Print Network [OSTI]

    Hollerbach, John M.

    DISPLAY OF FRICTION IN VIRTUAL ENVIRONMENTS BASED ON HUMAN FINGER PAD CHARACTERISTICS A. Nahvi, J City, UT 84112 ABSTRACT A friction display system is proposed for virtual environ- ments. Since a user the frictional properties of the human finger pad on 9 subjects by simultaneously recording force and movement

  2. ACC03-ASME0018 Controller Design for Flexible Systems with Friction

    E-Print Network [OSTI]

    Singh, Tarunraj

    ACC03-ASME0018 Controller Design for Flexible Systems with Friction: Linear Programming Approach of friction is presented. A linear program- ming technique for finding an optimal control of linear flexible systems is extended to frictional systems. A floating oscillator is used in the development, where

  3. Friction, Frontogenesis, and the Stratification of the Surface Mixed Layer LEIF THOMAS*

    E-Print Network [OSTI]

    Thompson, Andrew

    Friction, Frontogenesis, and the Stratification of the Surface Mixed Layer LEIF THOMAS* Department restratification resulting from frontogenesis in regions of confluent flow. Frictional forces acting of friction versus frontogenesis in the restratification of the mixed layer and are tested using numerical

  4. Internal friction in the ultrafast folding of the tryptophan cage q Linlin Qiu 1

    E-Print Network [OSTI]

    Hagen, Stephen J.

    Internal friction in the ultrafast folding of the tryptophan cage q Linlin Qiu 1 , Stephen J. Hagen is a diffusional process, and the speed of folding is controlled by the frictional forces that act important source of friction in folding reactions. By contrast, our studies of the folding dynamics

  5. Attractiveness of periodic orbits in parametrically forced systems with time-increasing friction

    E-Print Network [OSTI]

    Attractiveness of periodic orbits in parametrically forced systems with time-increasing friction-dimensional systems subject to a periodic force and study numer- ically how a time-varying friction affects oscillator in the presence of friction. We find that, if the damping coefficient increases in time up

  6. Friction of a slider on a granular layer: Nonmonotonic thickness dependence and effect of boundary conditions

    E-Print Network [OSTI]

    Kudrolli, Arshad

    Friction of a slider on a granular layer: Nonmonotonic thickness dependence and effect of boundary the effective friction encountered by a mass sliding on a granular layer as a function of bed thickness and boundary roughness conditions. The observed friction has minima for a small number of layers before

  7. A Concurrent Product-Development Approach for Friction-Stir Welded Vehicle-Underbody Structures

    E-Print Network [OSTI]

    Grujicic, Mica

    A Concurrent Product-Development Approach for Friction-Stir Welded Vehicle-Underbody Structures M technologies such as friction-stir welding (FSW) have to be employed. However, since FSW is a relatively new-survivable and ballistic threat-resistant military vehicles, friction-stir welding, process development 1. Introduction

  8. Acta Materialia 59 (2011) 2020-2028 Back of the envelope calculations in friction stir welding

    E-Print Network [OSTI]

    Cambridge, University of

    2011-01-01T23:59:59.000Z

    Acta Materialia 59 (2011) 2020-2028 1 Back of the envelope calculations in friction stir welding: friction stir welding; modeling; theory; velocity field; peak temperature; torque; hardness; aluminum in friction stir welding (FSW) [1-53] have been tested against experimental data for the joining of aluminum

  9. Statistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321

    E-Print Network [OSTI]

    Grujicic, Mica

    Statistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321 M. Grujicic AA5083, fatigue behavior, friction stir welding, maximum likelihood estimation 1. Introduction Friction stir welding (FSW) is a relatively new solid-state metal-joining process that was invented

  10. Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic

    E-Print Network [OSTI]

    Grujicic, Mica

    Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding (FSW) joints found limit, failure mechanisms, friction stir welding 1. Introduction In the context of military tactical

  11. Review: friction stir welding tools , H. K. D. H. Bhadeshia3

    E-Print Network [OSTI]

    Cambridge, University of

    Review: friction stir welding tools R. Rai1 , A. De2 , H. K. D. H. Bhadeshia3 and T. DebRoy*1 Friction stir welding (FSW) is a widely used solid state joining process for soft materials ability, mechanisms of tool degradation and process economics. Keywords: Friction stir welding, Tool

  12. Coupling Boltzmann and Navier-Stokes equations by friction

    SciTech Connect (OSTI)

    Bourgat, J.F. [INRIA, Le Chesnay (France)] [INRIA, Le Chesnay (France); Le Tallec, P. [Universite Paris, Dauphine (France)] [Universite Paris, Dauphine (France); [INRIA, Le Chesnay (France); Tidriri, M.D. [ICASE, Hampton, VA (United States)] [ICASE, Hampton, VA (United States)

    1996-09-01T23:59:59.000Z

    The aim of this paper is to introduce and validate a coupled Navier-Stokes Boltzman approach for the calculation of hypersonic rarefied flows around maneuvering vehicles. The proposed strategy uses locally a kinetic model in the boundary layer coupled through wall friction forces to a global Navier-Stokes solver. Different numerical experiments illustrate the potentialities of the method. 29 refs., 24 figs.

  13. Brownian ratchet in a thermal bath driven by Coulomb friction

    E-Print Network [OSTI]

    A. Gnoli; A. Petri; F. Dalton; G. Gradenigo; G. Pontuale; A. Sarracino; A. Puglisi

    2013-01-14T23:59:59.000Z

    The rectification of unbiased fluctuations, also known as the ratchet effect, is normally obtained under statistical non-equilibrium conditions. Here we propose a new ratchet mechanism where a thermal bath solicits the random rotation of an asymmetric wheel, which is also subject to Coulomb friction due to solid-on-solid contacts. Numerical simulations and analytical calculations demonstrate a net drift induced by friction. If the thermal bath is replaced by a granular gas, the well known granular ratchet effect also intervenes, becoming dominant at high collision rates. For our chosen wheel shape the granular effect acts in the opposite direction with respect to the friction-induced torque, resulting in the inversion of the ratchet direction as the collision rate increases. We have realized a new granular ratchet experiment where both these ratchet effects are observed, as well as the predicted inversion at their crossover. Our discovery paves the way to the realization of micro and sub-micrometer Brownian motors in an equilibrium fluid, based purely upon nano-friction.

  14. Wetting and friction on superoleophobic surfaces March 20, 2009

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    then focus on their friction properties, and es- tablish an important condition for their use as super-lubricating,15­18 . Similar surfaces can be produced to repel oil, but repelling both oil and water with the same surface is a true challenge since surfaces that repel water are usu- ally attracting oils. The recently introduced

  15. Nanomanipulation Experiments Exploring Frictional and Mechanical Properties of Carbon Nanotubes

    E-Print Network [OSTI]

    Falvo, Michael

    Nanomanipulation Experiments Exploring Frictional and Mechanical Properties of Carbon Nanotubes M that places the human operator directly into the feedback loop that controls surface manipulations. Using. The mechanical properties of carbon nanotubes have been demonstrated to be extraordinary. They have an elastic

  16. Sliding Friction with Polymer Brushes Rafael Tadmor,* Joanna Janik,

    E-Print Network [OSTI]

    Klein, Jacob

    across the polymer layers decays logarithmically with time, consistent with the relaxation of a network on the sliding velocity, an effect attributed to a velocity-dependent interpenetration of the opposing polymerSliding Friction with Polymer Brushes Rafael Tadmor,* Joanna Janik, and Jacob Klein Department

  17. Lateral position detection and control for friction stir systems

    DOE Patents [OSTI]

    Fleming, Paul (Boulder, CO); Lammlein, David (Houston, TX); Cook, George E. (Brentwood, TN); Wilkes, Don Mitchell (Nashville, TN); Strauss, Alvin M. (Nashville, TN); Delapp, David (Ashland City, TN); Hartman, Daniel A. (Santa Fe, NM)

    2010-12-14T23:59:59.000Z

    A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

  18. TBM tunnel friction values for the Grizzly Powerhouse Project

    SciTech Connect (OSTI)

    Stutsman, R.D. [Ensign & Buckley Consulting Engineers, Larkspur, CA (United States); Rothfuss, B.D. [Pacific Gas and Electric Co., San Francisco, CA (United States)

    1995-12-31T23:59:59.000Z

    Tunnel boring machine (TBM) driven water conveyance tunnels are becoming increasingly more common. Despite advances in tunnel engineering and construction technology, hydraulic performance data for TBM driven tunnels remains relatively unavailable. At the Grizzly Powerhouse Project, the TBM driven water conveyance tunnel was designed using friction coefficients developed from a previous PG&E project. A range of coefficients were selected to bound the possible hydraulic performance variations of the water conveyance system. These friction coefficients, along with the water conveyance systems characteristics, and expected turbine characteristics, were used in a hydraulic transient analysis to determine the expected system pressure fluctuations, and surge chamber performance. During startup test data, these performance characteristics were measured to allow comparison to the original design assumptions. During construction of the tunnel, plaster casts were made of the actual excavated tunnel unlined and fiber reinforced shotcrete lined surfaces. These castings were used to measure absolute roughness of the surfaces so that a friction coefficient could be developed using the Moody diagram and compare them against the design values. This paper compares the assumed frictional coefficient with computed coefficients from headlosses measured during startup testing, and plaster cast measurement calculations. In addition, a comparison of coefficients will be presented for an other TBM driven water conveyance tunnel constructed in the 1980`s.

  19. Casimir Friction Force and Energy Dissipation for Moving Harmonic Oscillators

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2010-01-14T23:59:59.000Z

    The Casimir friction problem for a pair of dielectric particles in relative motion is analyzed, utilizing a microscopic model in which we start from statistical mechanics for harmonically oscillating particles at finite temperature moving nonrelativistically with constant velocity. The use of statistical mechanics in this context has in our opinion some definite advantages, in comparison with the more conventional quantum electrodynamic description of media that involves the use of a refractive index. The statistical-mechanical description is physical and direct, and the oscillator model, in spite of its simplicity, is nevertheless able to elucidate the essentials of the Casimir friction. As is known, there are diverging opinions about this kind of friction in the literature. Our treatment elaborates upon, and extends, an earlier theory presented by us back in 1992. There we found a finite friction force at any finite temperature, whereas at zero temperature the model led to a zero force. As an additional development in the present paper we evaluate the energy dissipation making use of an exponential cutoff truncating the relative motion of the oscillators. For the dissipation we also establish a general expression that is not limited to the simple oscillator model.

  20. Smoluchowski-Kramers approximation in the case of variable friction

    E-Print Network [OSTI]

    Mark Freidlin; Wenqing Hu

    2012-03-03T23:59:59.000Z

    We consider the small mass asymptotics (Smoluchowski-Kramers approximation) for the Langevin equation with a variable friction coefficient. The limit of the solution in the classical sense does not exist in this case. We study a modification of the Smoluchowski-Kramers approximation. Some applications of the Smoluchowski-Kramers approximation to problems with fast oscillating or discontinuous coefficients are considered.

  1. TEMPORARILY ALLOYING TITANIUM TO FACILITATE FRICTION STIR WELDING

    SciTech Connect (OSTI)

    Hovanski, Yuri

    2009-05-06T23:59:59.000Z

    While historically hydrogen has been considered an impurity in titanium, when used as a temporary alloying agent it promotes beneficial changes to material properties that increase the hot-workability of the metal. This technique known as thermohydrogen processing was used to temporarily alloy hydrogen with commercially pure titanium sheet as a means of facilitating the friction stir welding process. Specific alloying parameters were developed to increase the overall hydrogen content of the titanium sheet ranging from commercially pure to 30 atomic percent. Each sheet was evaluated to determine the effect of the hydrogen content on process loads and tool deformation during the plunge phase of the friction stir welding process. Two materials, H-13 tool steel and pure tungsten, were used to fabricate friction stir welding tools that were plunged into each of the thermohydrogen processed titanium sheets. Tool wear was characterized and variations in machine loads were quantified for each tool material and weld metal combination. Thermohydrogen processing was shown to beneficially lower plunge forces and stabilize machine torques at specific hydrogen concentrations. The resulting effects of hydrogen addition to titanium metal undergoing the friction stir welding process are compared with modifications in titanium properties documented in modern literature. Such comparative analysis is used to explain the variance in resulting process loads as a function of the initial hydrogen concentration of the titanium.

  2. Modeling of friction-induced deformation and microstructures.

    SciTech Connect (OSTI)

    Michael, Joseph Richard; Prasad, Somuri V.; Jungk, John Michael; Cordill, Megan J. (University of Minnesota); Bammann, Douglas J.; Battaile, Corbett Chandler; Moody, Neville Reid; Majumdar, Bhaskar Sinha (New Mexico Institure of Mining and Technology)

    2006-12-01T23:59:59.000Z

    Frictional contact results in surface and subsurface damage that could influence the performance, aging, and reliability of moving mechanical assemblies. Changes in surface roughness, hardness, grain size and texture often occur during the initial run-in period, resulting in the evolution of subsurface layers with characteristic microstructural features that are different from those of the bulk. The objective of this LDRD funded research was to model friction-induced microstructures. In order to accomplish this objective, novel experimental techniques were developed to make friction measurements on single crystal surfaces along specific crystallographic surfaces. Focused ion beam techniques were used to prepare cross-sections of wear scars, and electron backscattered diffraction (EBSD) and TEM to understand the deformation, orientation changes, and recrystallization that are associated with sliding wear. The extent of subsurface deformation and the coefficient of friction were strongly dependent on the crystal orientation. These experimental observations and insights were used to develop and validate phenomenological models. A phenomenological model was developed to elucidate the relationships between deformation, microstructure formation, and friction during wear. The contact mechanics problem was described by well-known mathematical solutions for the stresses during sliding friction. Crystal plasticity theory was used to describe the evolution of dislocation content in the worn material, which in turn provided an estimate of the characteristic microstructural feature size as a function of the imposed strain. An analysis of grain boundary sliding in ultra-fine-grained material provided a mechanism for lubrication, and model predictions of the contribution of grain boundary sliding (relative to plastic deformation) to lubrication were in good qualitative agreement with experimental evidence. A nanomechanics-based approach has been developed for characterizing the mechanical response of wear surfaces. Coatings are often required to mitigate friction and wear. Amongst other factors, plastic deformation of the substrate determines the coating-substrate interface reliability. Finite element modeling has been applied to predict the plastic deformation for the specific case of diamond-like carbon (DLC) coated Ni alloy substrates.

  3. Microstructural issues in a friction-stir-welded aluminum alloy

    SciTech Connect (OSTI)

    Flores, O.V.; Kennedy, C.; Murr, L.E.; Brown, D.; Pappu, S.; Nowak, B.M.; McClure, J.C. [Univ. of Texas, El Paso, TX (United States)] [Univ. of Texas, El Paso, TX (United States)

    1998-02-03T23:59:59.000Z

    Recent observations of microstructures associated with friction-stir welding (FSW) in a number of aluminum alloys have consistently demonstrated the actual weld zone to consist of a (dynamically) recrystallized grain structure resulting from the extreme, solid-state, plastic deformation characterizing the process. Because of solubilities associated with the various precipitates in 7075 and 6061 aluminum alloys, and the fact that the precipitates were either homogeneously distributed throughout both the original (unwelded) work-piece plates and the well zones (or formed varying densities of Widmanstaetten patterns within the original and recrystallized grains), it has been difficult to follow the stirring of stable, second-phase particles from the base metal (work-piece) into the weld zone. In the present investigation, a compositionally modified 1100 aluminum alloy (nominally 99.2% Al, 0.5% Fe, 0.15% Cu, 0.12% Si, 0.05 Mn, 0.04 Ti, balance in weight percent of Be and Mg), forming a stable microdendritic (second-phase), equiaxed, cell structure was friction-stir welded. These thermally stable, geometrically specific, precipitates in the base metal were compared with their disposition within the friction-stir-weld zone. In addition, as-cast plates of this alloy were cold-rolled 50% and friction-stir-welded in order to compare these two schedules (as-cast and 50% cold-rolled) in terms of residual hardness variations and related microstructural issues as well as the effect of prior deformation on the friction-stir welding process.

  4. UPDATE AND ENHANCEMENT OF ODOT'S CRASH REDUCTION FACTORS

    E-Print Network [OSTI]

    Bertini, Robert L.

    A Printed on recycled paper #12;ii SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SIUPDATE AND ENHANCEMENT OF ODOT'S CRASH REDUCTION FACTORS Final Report SPR 612 by Christopher M and Enhancement of ODOT's Crash Reduction Factors 6. Performing Organization Code 7. Author(s) Christopher M

  5. Variable enstrophy flux and energy spectrum in two-dimensional turbulence with Ekman friction

    E-Print Network [OSTI]

    Mahendra K. Verma

    2012-03-23T23:59:59.000Z

    Experiments and numerical simulations reveal that in the forward cascade regime, the energy spectrum of two-dimensional turbulence with Ekman friction deviates from Kraichnan's prediction of $k^{-3}$ power spectrum. In this letter we explain this observation using an analytic model based on variable enstrophy flux arising due to Ekman friction. We derive an expression for the enstrophy flux which exhibits a logarithmic dependence in the inertial range for the Ekman-friction dominated flows. The energy spectrum obtained using this enstrophy flux shows a power law scaling for large Reynolds number and small Ekman friction, but has an exponential behaviour for large Ekman friction and relatively small Reynolds number.

  6. Economic evaluation of volume reduction for Defense transuranic waste

    SciTech Connect (OSTI)

    Brown, C.M.

    1981-07-01T23:59:59.000Z

    This study evaluates the economics of volume reduction of retrievably stored and newly generated DOE transuranic waste by comparing the costs of reduction of the waste with the savings possible in transportation and disposal of the waste. The report develops a general approach to the comparison of TRU waste volume reduction costs and cost savings, establishes an initial set of cost data, and develops conclusions to support selecting technologies and facilities for the disposal of DOE transuranic waste. Section I outlines the analysis which considers seven types of volume reduction from incineration and compaction of combustibles to compaction, size reduction, shredding, melting, and decontamination of metals. The study considers the volume reduction of contact-handled newly generated, and retrievably stored DOE transuranic waste. Section II of this report describes the analytical approach, assumptions, and flow of waste material through sites. Section III presents the waste inventories, disposal, and transportation savings with volume reduction and the volume reduction techniques and savings.

  7. Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys

    SciTech Connect (OSTI)

    Pinkerton, G.W.

    1993-12-31T23:59:59.000Z

    The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression.

  8. nature physics | VOL 6 | MARCH 2010 | www.nature.com/naturephysics 155 How do you solve a problem like friction?

    E-Print Network [OSTI]

    Loss, Daniel

    a problem like friction? I learned to respect friction, as a phenomenon with many nuances, when I friction between the ball and floor, work out, first, how far the ball goes before it is rolling. The first part, I quickly demonstrated, is easy. Assuming the force of sliding friction is independent

  9. High temperature low-cycle fatigue of friction welded joints - type 304-304 stainless steel and alloy 718-718 nickel base superalloy

    SciTech Connect (OSTI)

    Wakai, T. (Power Reactor and Nuclear Fuel Development Corp., Ibaraki (Japan). Oarai Engineering Center); Sakane, M.; Ohnami, M. (Ritsumeikan Univ., Kyoto (Japan). Dept. of Mechanical Engineering); Okita, K. (Hyogo Prefectural Inst. of Industrial Research, Miki (Japan). Technical Center for Machinery and Metals); Fukuchi, Y. (Hyogo Prefectural Inst. of Industrial Research, Kobe (Japan))

    1993-01-01T23:59:59.000Z

    This paper assesses the high-temperature low-cycle fatigue of the Type 304 stainless steel and Alloy 718 superalloy friction-welded joints. Strain controlled low-cycle fatigue tests for 304-304 and 718-718 friction-welded specimens were carried out at 923 K in air to obtain the fatigue strength of the joints. These materials were selected as the cyclic hardening and softening materials, respectively. The 304-304 welded specimens showed inferior fatigue strength in comparison with the base metal while the 718-718 specimens exhibited fatigue strength equivalent to that of the base metal. The difference in the fatigue strength between the two materials is discussed from the viewpoint of the cyclic deformation behavior and strain reduction at weld interface.

  10. Micro-beam friction liner and method of transferring energy

    DOE Patents [OSTI]

    Mentesana, Charles (Leawood, KS)

    2007-07-17T23:59:59.000Z

    A micro-beam friction liner adapted to increase performance and efficiency and reduce wear in a piezoelectric motor or actuator or other device using a traveling or standing wave to transfer energy in the form of torque and momentum. The micro-beam friction liner comprises a dense array of micro-beam projections having first ends fixed relative to a rotor and second ends projecting substantially toward a plurality of teeth of a stator, wherein the micro-beam projections are compressed and bent during piezoelectric movement of the stator teeth, thereby storing the energy, and then react against the stator teeth to convert the stored energy stored to rotational energy in the rotor.

  11. Simple LMFBR axial-flow friction-factor correlation

    SciTech Connect (OSTI)

    Chan, Y.N.; Todreas, N.E.

    1982-12-01T23:59:59.000Z

    Complicated LMFBR axial lead-length averaged friction-factor correlations are reduced to an easy, ready-to-use function of bundle Reynolds number for wire-wrapped bundles. The function together with the power curves to calculate the associated constants are incorporated in a computer preprocessor, EZFRIC. The constants required for the calculation of the subchannels and bundle friction factors are derived and correlated into power curves of geometrical parameters. A computer program, FRIC, which can alternatively be used to accurately calculate these constants is also included. The accurate values of the constants and the corresponding values predicted by the power curves and percentage error of prediction are tabulated for a wide variety of geometries of interest.

  12. Rack-and-pinion effects in molecular rolling friction

    E-Print Network [OSTI]

    Oleg M. Braun; Erio Tosatti

    2008-09-05T23:59:59.000Z

    Rolling lubrication with spherical molecules working as 'nanobearings' has failed experimentally so far, without a full understanding of the physics involved and of the reasons why. Past model simulations and common sense have shown that molecules can only roll when they are not too closely packed to jam. The same type of model simulations now shows in addition that molecular rolling friction can develop deep minima once the molecule's peripheral 'pitch' can match the substrate periodicity, much as ordinary cogwheels do in a rack-and-pinion system. When the pinion-rack matching is bad, the driven molecular rolling becomes discontinuous and noisy, whence energy is dissipated and friction is large. This suggests experiments to be conducted by varying the rack-and-pinion matching. That could be pursued not only by changing molecules and substrates, but also by applying different sliding directions within the same system, or by applying pressure, to change the effective matching.

  13. Friction and the oscillatory motion of granular flows

    E-Print Network [OSTI]

    Lydie Staron

    2012-11-26T23:59:59.000Z

    This contribution reports on numerical simulations of 2D granular flows on erodible beds. The broad aim is to investigate whether simple flows of model granular matter exhibits spontaneous oscillatory motion in generic flow conditions, and in this case, whether the frictional properties of the contacts between grains may affect the existence or the characteristics of this oscillatory motion. The analysis of different series of simulations show that the flow develops an oscillatory motion with a well-defined frequency which increases like the inverse of the velocity's square root. We show that the oscillation is essentially a surface phenomena. The amplitude of the oscillation is higher for lower volume fractions, and can thus be related to the flow velocity and grains friction properties. The study of the influence of the periodic geometry of the simulation cell shows no significant effect. These results are discussed in relation to sonic sands.

  14. Friction Properties of Molybdenum Alloyed Steel at Elevated Temperatures

    SciTech Connect (OSTI)

    Li Jianliang; Xiong Dangsheng [Department of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094 (China); Wu Hongyan [College of Math and Physics, Nanjing University of Information and Technology, Nanjing, 210044 (China)

    2011-01-17T23:59:59.000Z

    The high-temperature properties of steel surface can be improved by molybdenum surface alloying. Molybdenzing was carried out on carbon steel in the multi-function double glow plasma surface alloying furnace. The friction and wear tests were conducted on a high temperature ball-on-disk tribometer under the temperature of 25 deg. C{approx}600 deg. C. The contents of alloy element varied with alloyed layer were detected by SEM attached with EDS. The molybdenized layer is composed of the deposited layer and diffused layer. The micro-hardness of alloyed layer decreases from HV650 on the top layer to HV240. The friction coefficient of molybdenized layer decreases from 0.5{approx}0.6 to 0.2{approx}0.3 and wear rate decreases by 20% at elevated temperature after molybdenizing.

  15. Friction vs Texture at the Approach of a Granular Avalanche

    E-Print Network [OSTI]

    Lydie Staron; Farhang Radjai

    2005-05-04T23:59:59.000Z

    We perform a novel analysis of the granular texture of a granular bed close to stability limit. Our analysis is based on a unique criterion of friction mobilisation in a simulated two-dimensional packing. In this way, we recover the bimodal character of granular texture, and the coexistence of weak and strong phases in the sense of distinct contacts populations. Moreover, we show the existence of a well-defined subset of contacts within the weak contact network. These contacts are characterized by their important friction, and form a highly coherent population in terms of fabric. They play an antagonistic role with respect to force chains. We are thus able to discriminate between incoherent contacts and coherent contacts in the weak phase, and to specify the role that the latter plays in the destabilisation process.

  16. Liquid friction on charged surfaces: from hydrodynamic slippage to electrokinetics

    E-Print Network [OSTI]

    Laurent Joly; Christophe Ybert; Emmanuel Trizac; Lyderic Bocquet

    2006-07-19T23:59:59.000Z

    Hydrodynamic behavior at the vicinity of a confining wall is closely related to the friction properties of the liquid/solid interface. Here we consider, using Molecular Dynamics simulations, the electric contribution to friction for charged surfaces, and the induced modification of the hydrodynamic boundary condition at the confining boundary. The consequences of liquid slippage for electrokinetic phenomena, through the coupling between hydrodynamics and electrostatics within the electric double layer, are explored. Strong amplification of electro-osmotic effects is revealed, and the non-trivial effect of surface charge is discussed. This work allows to reconsider existing experimental data, concerning Zeta potentials of hydrophobic surfaces and suggest the possibility to generate ``giant'' electro-osmotic and electrophoretic effects, with direct applications in microfluidics.

  17. A novel system to study wear, friction, and lubricants

    SciTech Connect (OSTI)

    Maamouri, M.; Masson, J.F.; Marchand, N.J. (Ecole Polytechnique, Montreal, Quebec (Canada). Dept. de Metallurgie et de Genie des Materiaux)

    1994-08-01T23:59:59.000Z

    A novel enclosed (pressurized) multispecimen wear testing system was design and built to allow the fully computerized on-line measurement and control of friction, wear, and lubricants of different materials (metals, ceramics, composites, and plastics). This system is described in detail. The tribological parameters can be adjusted and controlled to reproduce the actual conditions that prevail in machine components. Several examples of the capabilities of the system are presented.

  18. Friction Control Solutions Inc FriCSo | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia: Energy Resources Jump to: navigation, search Equivalent URI DBpediaFredonia,Iowa BioProcessAreaFresnoFriction

  19. Hydrodynamics of rapidly rotating superfluid neutron stars with mutual friction

    E-Print Network [OSTI]

    A. Passamonti; N. Andersson

    2010-04-26T23:59:59.000Z

    We study time evolutions of superfluid neutron stars, focussing on the nature of the oscillation spectrum, the effect of mutual friction force on the oscillations and the hydrodynamical spin-up phase of pulsar glitches. We linearise the dynamical equations of a Newtonian two-fluid model for rapidly rotating backgrounds. In the axisymmetric equilibrium configurations, the two fluid components corotate and are in beta-equilibrium. We use analytical equations of state that generate stratified and non-stratified stellar models, which enable us to study the coupling between the dynamical degrees of freedom of the system. By means of time evolutions of the linearised dynamical equations, we determine the spectrum of axisymmetric and non-axisymmetric oscillation modes, accounting for the contribution of the gravitational potential perturbations, i.e. without adopting the Cowling approximation. We study the mutual friction damping of the superfluid oscillations and consider the effects of the non-dissipative part of the mutual friction force on the mode frequencies. We also provide technical details and relevant tests for the hydrodynamical model of pulsar glitches discussed by Sidery, Passamonti and Andersson (2010). In particular, we describe the method used to generate the initial data that mimic the pre-glitch state, and derive the equations that are used to extract the gravitational-wave signal.

  20. Final report - Reduction of mercury in saturated subsurface sediments and its potential to mobilize mercury in its elemental form

    SciTech Connect (OSTI)

    Bakray, Tamar [Rutgers University

    2013-06-13T23:59:59.000Z

    The goal of our project was to investigate Hg(II) reduction in the deep subsurface. We focused on microbial and abiotic pathways of reduction and explored how it affected the toxicity and mobility of Hg in this unique environment. The project’s tasks included: 1. Examining the role of mer activities in the reduction of Hg(II) in denitrifying enrichment cultures; 2. Investigating the biotic/abiotic reduction of Hg(II) under iron reducing conditions; 3. Examining Hg(II) redox transformations under anaerobic conditions in subsurface sediments from DOE sites.

  1. PLAINS CO2 REDUCTION PARTNERSHIP

    SciTech Connect (OSTI)

    Edward N. Steadman

    2004-07-01T23:59:59.000Z

    The Plains Co{sub 2} Reduction (PCOR) Partnership continues to make great progress. Task 2 (Technology Deployment) activities have focused on developing information on deployment issues to support Task 5 activities by providing information to be used to assess CO{sub 2} sequestration opportunities in the PCOR Partnership region. Task 3 (Public Outreach) activities have focused on developing an informational video about CO{sub 2} sequestration. Progress in Task 4 (Sources, Sinks, and Infrastructure) has included the continued collection of data regarding CO{sub 2} sources and sinks and data on the performance and costs for CO{sub 2} separation, capture, treatment, and compression for pipeline transportation. Task 5 (Modeling and Phase II Action Plans) activities have focused on screening and qualitatively assessing sequestration options. Task 5 activities also continue to be useful in structuring data collection and other activities in Tasks 2, 3, and 5.

  2. PLAINS CO2 REDUCTION PARTNERSHIP

    SciTech Connect (OSTI)

    Edward N. Steadman; John A. Harju; Erin M. O'Leary; James A. Sorensen; Daniel J. Daly; Melanie D. Jensen; Thea E. Reikoff

    2005-01-01T23:59:59.000Z

    The Plains CO{sub 2} Reduction (PCOR) Partnership continues to make great progress. Task 2 (Technology Deployment) focused on developing information regarding deployment issues to support Task 5 (Modeling and Phase II Action Plans) by providing information to be used to assess CO{sub 2} sequestration opportunities in the PCOR Partnership region. Task 3 (Public Outreach) focused on developing an informational video about CO{sub 2} sequestration. Progress in Task 4 (Sources, Sinks, and Infrastructure) included the continued collection of data regarding CO{sub 2} sources and sinks and data on the performance and costs for CO{sub 2} separation, capture, treatment, and compression for pipeline transportation. Task 5 focused on screening and qualitatively assessing sequestration options. Task 5 activities also continue to be useful in structuring data collection and other activities in Tasks 2, 3, and 5.

  3. Nuclear Waste Reduction

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Nuclear Waste Reduction Pyroprocessing is a promising technology for recycling used nuclear fuel and improving the associated waste management options. The process...

  4. Effects of Stone-Wales and vacancy defects in atomic-scale friction on defective graphite

    SciTech Connect (OSTI)

    Sun, Xiao-Yu [Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072 (China); Key Laboratory of Hubei Province for Water Jet Theory and New Technology, Wuhan University, Wuhan 430072 (China); Wu, RunNi; Xia, Re [Key Laboratory of Hubei Province for Water Jet Theory and New Technology, Wuhan University, Wuhan 430072 (China); Chu, Xi-Hua; Xu, Yuan-Jie, E-mail: yj-xu@whu.edu.cn [Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072 (China)

    2014-05-05T23:59:59.000Z

    Graphite is an excellent solid lubricant for surface coating, but its performance is significantly weakened by the vacancy or Stone-Wales (SW) defect. This study uses molecular dynamics simulations to explore the frictional behavior of a diamond tip sliding over a graphite which contains a single defect or stacked defects. Our results suggest that the friction on defective graphite shows a strong dependence on defect location and type. The 5-7-7-5 structure of SW defect results in an effectively negative slope of friction. For defective graphite containing a defect in the surface, adding a single vacancy in the interior layer will decrease the friction coefficients, while setting a SW defect in the interior layer may increase the friction coefficients. Our obtained results may provide useful information for understanding the atomic-scale friction properties of defective graphite.

  5. Friction Stir Spot Welding of Advanced High Strength Steels II | Department

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-UpHeatMulti-Dimensional Electrical Resistivity Structure |AccomplishmentsDepartment ofof

  6. Photosystem II

    ScienceCinema (OSTI)

    James Barber

    2010-09-01T23:59:59.000Z

    James Barber, Ernst Chain Professor of Biochemistry at Imperial College, London, gives a BSA Distinguished Lecture titled, "The Structure and Function of Photosystem II: The Water-Splitting Enzyme of Photosynthesis."

  7. Interplay of friction and noise and enhancement of disoriented chiral condensate

    E-Print Network [OSTI]

    A. K. Chaudhuri

    2000-11-01T23:59:59.000Z

    Using the Langevin equation for the linear $\\sigma$ model, we have investigated the effect of friction and noise on the possible disoriented chiral condensate formation. Friction and noise are supposed to suppress longwavelength oscillations and growth of disoriented chiral condensate domains. Details simulation shows that for heavy ion collisions, interplay of friction and noise occur in such a manner that formation of disoriented chiral condensate domains are enhanced.

  8. E-Print Network 3.0 - alloy friction stir Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and Young... conditions. Most works on internal friction have been done on dilute solid solution alloys. Some works have... . This is a multi-element alloy prepared by...

  9. E-Print Network 3.0 - adhesive microstructure friction Sample...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    at Berkeley Collection: Physics 20 How to get the yield locus of an adhesive powder from a single numerical experiment Summary: with experiments. The effect of friction...

  10. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect (OSTI)

    Victor W. Wong; Tian Tian; Grant Smedley

    2003-08-28T23:59:59.000Z

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. A detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various low-friction strategies and concepts have been explored, and engine experiments will validate these concepts. An iterative process of experimentation, simulation and analysis, will be followed with the goal of demonstrating a complete optimized low-friction engine system. As planned, MIT has developed guidelines for an initial set of low-friction piston-ring-pack designs. Current recommendations focus on subtle top-piston-ring and oil-control-ring characteristics. A full-scale Waukesha F18 engine has been installed at Colorado State University and testing of the baseline configuration is in progress. Components for the first design iteration are being procured. Subsequent work includes examining the friction and engine performance data and extending the analyses to other areas to evaluate opportunities for further friction improvement and the impact on oil consumption/emission and wear, towards demonstrating an optimized reduced-friction engine system.

  11. Friction stir welding tool and process for welding dissimilar materials

    DOE Patents [OSTI]

    Hovanski, Yuri; Grant, Glenn J; Jana, Saumyadeep; Mattlin, Karl F

    2013-05-07T23:59:59.000Z

    A friction stir welding tool and process for lap welding dissimilar materials are detailed. The invention includes a cutter scribe that penetrates and extrudes a first material of a lap weld stack to a preselected depth and further cuts a second material to provide a beneficial geometry defined by a plurality of mechanically interlocking features. The tool backfills the interlocking features generating a lap weld across the length of the interface between the dissimilar materials that enhances the shear strength of the lap weld.

  12. Curvature effect on tearing modes in presence of neoclassical friction

    SciTech Connect (OSTI)

    Maget, Patrick; Mellet, Nicolas; Meshcheriakov, Dmytro; Garbet, Xavier [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France)] [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France); Lütjens, Hinrich [Centre de Physique Théorique, Ecole Polytechnique, CNRS (France)] [Centre de Physique Théorique, Ecole Polytechnique, CNRS (France)

    2013-11-15T23:59:59.000Z

    Neoclassical physics (here associated to the poloidal variation of the magnetic field strength along field lines in a tokamak) is well known for driving self-generated plasma current and nonlinear magnetic islands associated to it in high performance, ITER relevant plasma discharges. It is demonstrated that the neoclassical friction between a magnetic perturbation and plasma flow already impacts magnetic islands in the linear regime, by inducing a weakening of curvature stabilization for tearing modes. This conclusion holds in particular for regimes where convection is influencing the pressure dynamics, as shown using a simple analytical model and confirmed in full Magneto-Hydro-Dynamics simulations.

  13. Fluctuations in a kinetic transport model for quantum friction

    E-Print Network [OSTI]

    Roland Bauerschmidt; Wojciech de Roeck; Jürg Fröhlich

    2014-03-23T23:59:59.000Z

    We consider a linear Boltzmann equation that arises in a model for quantum friction. It describes a particle that is slowed down by the emission of bosons. We study the stochastic process generated by this Boltzmann equation and we show convergence of its spatial trajectory to a multiple of Brownian motion with exponential scaling. The asymptotic position of the particle is finite in mean, even though its absolute value is typically infinite. This is contrasted to an approximation that neglects the influence of fluctuations, where the mean asymptotic position is infinite.

  14. Non-equilibrium Statistical Approach to Friction Models

    E-Print Network [OSTI]

    Shoichi Ichinose

    2014-04-26T23:59:59.000Z

    A geometric approach to the friction phenomena is presented. It is based on the holographic view which has recently been popular in the theoretical physics community. We see the system in one-dimension-higher space. The heat-producing phenomena are most widely treated by using the non-equilibrium statistical physics. We take 2 models of the earthquake. The dissipative systems are here formulated from the geometric standpoint. The statistical fluctuation is taken into account by using the (generalized) Feynman's path-integral.

  15. Radiative friction on an excited atom moving in vacuum

    E-Print Network [OSTI]

    Wei Guo

    2012-04-30T23:59:59.000Z

    It is known that, when an excited atom spontaneously emits one photon, two effects are produced. First, the atom's internal and external states are entangled with the states of the emitted photon. Second, the atom receives a momentum transfered from the photon. In this work, the dynamics of such an atom in vacuum is studied. Through a specific calculation, it is demonstrated that these effects cause the atom to experience, on average, a friction force opposite to its initial velocity. Properties of the force are also discussed.

  16. Damping of Neutron Star Shear Modes by Superfluid Friction

    E-Print Network [OSTI]

    P. B. Jones

    2003-01-07T23:59:59.000Z

    The forced motion of superfluid vortices in shear oscillations of rotating solid neutron star matter produces damping of the mode. A simple model of the unpinning and repinning processes is described, with numerical calculations of the consequent energy decay times. These are of the order of 1 s or more for typical anomalous X-ray pulsars but become very short for the general population of radio pulsars. The superfluid friction processes considered here may also be significant for the damping of r-modes in rapidly rotating neutron stars.

  17. Frictional dissipation of polymeric solids vs interfacial glass transition

    E-Print Network [OSTI]

    Lionel Bureau; Christiane Caroli; Tristan Baumberger

    2006-07-19T23:59:59.000Z

    We present single contact friction experiments between a glassy polymer and smooth silica substrates grafted with alkylsilane layers of different coverage densities and morphologies. This allows us to adjust the polymer/substrate interaction strength. We find that, when going from weak to strong interaction, the response of the interfacial junction where shear localizes evolves from that of a highly viscous threshold fluid to that of a plastically deformed glassy solid. This we analyse as resulting from an interaction-induced ``interfacial glass transition'' helped by pressure.

  18. Evaluation of friction loss in flexible and galvanized duct

    E-Print Network [OSTI]

    Zimmermann, Carlos Michael Alberto

    1985-01-01T23:59:59.000Z

    /d ratios ranging from 1 to 5. Statistical analysis of the data indicated that there was a difference in the equivalent length mean data and that the interaction between r/d ratio and duct size, r/d ratio and duct type, and duct type and duct size.... . . 51 APPENDIX F ADC STANDARD REPORTING FORMS ()E AND ()E(M). . . 55 APPENDIX G EQUATIONS UTILIZED TO CONVERT FRICTION LOSS DATA TO EQUIVALENT LENGTHS APPENDIX H 58 RESULTS FROM AIR FLOW VOLUME REPRODUCIBILITY TEST. APPENDIX I 61 DATA...

  19. Precipitate stability and recrystallisation in the weld nuggets of friction stir welded Al-Mg-Si and Al-Mg-Sc alloys.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Precipitate stability and recrystallisation in the weld nuggets of friction stir welded Al Two different precipitate hardening aluminium alloys processed by friction stir welding were of continuous and discontinuous recrystallisation occurred in the weld nugget. Keywords friction stir welding

  20. Friction Stir Spot Welding of DP780 Carbon Steel

    SciTech Connect (OSTI)

    Santella, Michael L [ORNL; Hovanski, Yuri [ORNL; Frederick, David Alan [ORNL; Grant, Glenn J [ORNL; Dahl, Michael E [ORNL

    2010-01-01T23:59:59.000Z

    Friction stir spot welds were made in uncoated and galvannealed DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1 to 10 s. Increasing tool rotation speed from 800 to 1600 rev min{sup -1} increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap shear strengths exceeding 10 {center_dot} 3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.

  1. Micro-origin of Macro-strength: Friction

    E-Print Network [OSTI]

    Alex X. Jerves; José E. Andrade

    2012-12-11T23:59:59.000Z

    This paper presents an analytical study about the behavior of arbitrary shaped and sized non-cohesive two-dimensional granular materials. Several mechanical properties and relations are unraveled by connecting micro and macro scales in an explicit fashion that, at the same time, provides the basis of an analytical-theoretical framework for the development of new multi-scale techniques. Furthermore, the work herein presented is based on three main ideas that are developed and connected progressively; namely, the obtention of explicit expressions that enable us to relate micro-scale parameters, such as contact forces and fabric, to stress as a macro (continuum) physical property. Then, with these powerful tools, physical connections and relations between the mentioned micro-parameters and macro-constitutive parameters, in specific, Mohr-Coulomb's mobilized internal friction angle, are established. Finally, a non-linear optimization problem, which includes physical constraints at the contact point level, is proposed and solved in order to find the limit (maximum) internal friction angle in terms of the aforementioned micro-parameters. Thus, throughout this theoretical study, some important features about strength, anisotropy, contact buckling, and non-uniqueness of systems of contact forces are extracted, allowing us to have a deeper insight, as well as, a better understanding of the mechanical behavior of such complex-to-model materials.

  2. SECULAR DYNAMICAL ANTI-FRICTION IN GALACTIC NUCLEI

    SciTech Connect (OSTI)

    Madigan, Ann-Marie; Levin, Yuri, E-mail: madigan@strw.leidenuniv.nl [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

    2012-07-20T23:59:59.000Z

    We identify a gravitational-dynamical process in near-Keplerian potentials of galactic nuclei that occurs when an intermediate-mass black hole (IMBH) is migrating on an eccentric orbit through the stellar cluster towards the central supermassive black hole. We find that, apart from conventional dynamical friction, the IMBH experiences an often much stronger systematic torque due to the secular (i.e., orbit-averaged) interactions with the cluster's stars. The force which results in this torque is applied, counterintuitively, in the same direction as the IMBH's precession and we refer to its action as 'secular dynamical anti-friction' (SDAF). We argue that SDAF, and not the gravitational ejection of stars, is responsible for the IMBH's eccentricity increase seen in the initial stages of previous N-body simulations. Our numerical experiments, supported by qualitative arguments, demonstrate that (1) when the IMBH's precession direction is artificially reversed, the torque changes sign as well, which decreases the orbital eccentricity; (2) the rate of eccentricity growth is sensitive to the IMBH migration rate, with zero systematic eccentricity growth for an IMBH whose orbit is artificially prevented from inward migration; and (3) SDAF is the strongest when the central star cluster is rapidly rotating. This leads to eccentricity growth/decrease for the clusters rotating in the opposite/same direction relative to the IMBH's orbital motion.

  3. Mercury reduction and cell-surface adsorption by Geobacter sulfurreducens PCA

    SciTech Connect (OSTI)

    Hu, Haiyan [ORNL] [ORNL; Lin, Hui [ORNL] [ORNL; Zheng, Wang [ORNL] [ORNL; Feng, Xinbin [ORNL] [ORNL; Liang, Liyuan [ORNL] [ORNL; Elias, Dwayne A [ORNL] [ORNL; Gu, Baohua [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    Both reduction and surface adsorption of mercuric mercury [Hg(II)] are found to occur simultaneously on G. sulfurreducens PCA cells under dark, anaerobic conditions. Reduction of Hg(II) to elemental Hg(0) initially follows a pseudo-first order kinetics with a half-life of < 2 h in the presence of 50 nM Hg(II) and 1011 cells L-1 in a phosphate buffer (pH 7.4). Multiple gene deletions of the outer membrane cytochromes in this organism resulted in decrease in reduction rate from ~ 0.3 to 0.05 h-1, and reduction was nearly absent with heat-killed cells or in the cell filtrate. Adsorption of Hg(II) by cells is found to compete with, and thus inhibit, Hg(II) reduction. Depending on the Hg to cell ratio, maximum Hg(II) reduction was observed at about 5 10-19 mol Hg cell-1, but reduction terminated at a low Hg to cell ratio (< 10-20 mol Hg cell-1). This inhibitory effect is attributed to strong binding between Hg(II) and the thiol ( SH) functional groups on cells and validated by experiments in which the sorbed Hg(II) was readily exchanged by thiols (e.g., glutathione) but not by carboxylic ligands such as ethylenediaminetetraacetate (EDTA). We suggest that coupled Hg(II)-cell interactions, i.e., reduction and surface binding, could be important in controlling Hg species transformation and bioavailability and should therefore be considered in microbial Hg(II) uptake and methylation studies.

  4. Quantum Lubrication: Suppression of Friction in a First Principle Four Stroke Heat Engine

    E-Print Network [OSTI]

    Tova Feldmann; Ronnie Kosloff

    2005-09-19T23:59:59.000Z

    A quantum model of a heat engine resembling the Otto cycle is employed to explore strategies to suppress frictional losses. These losses are caused by the inability of the engine's working medium to follow adiabatically the change in the Hamiltonian during the expansion and compression stages. By adding external noise to the engine, frictional losses can be suppressed.

  5. Frictional powders: Ratcheting under periodic strain in 3D , C. T. David2

    E-Print Network [OSTI]

    Luding, Stefan

    Frictional powders: Ratcheting under periodic strain in 3D S. Luding1 , C. T. David2 , R. Garcia the (deviatoric) stress- strain relation a ratchet-like behavior is observed: Increasing the coefficient of friction leads to a transition from ratcheting to shake-down, i.e., the accumulation of strain stops

  6. Masatsu kakuhan setsugo "Friction Stir Welding Complete aspects of FSW" Japan Welding Society

    E-Print Network [OSTI]

    Cambridge, University of

    Masatsu kakuhan setsugo ­ "Friction Stir Welding ­ Complete aspects of FSW" Japan Welding Society years ago that the Friction Stir Welding (FSW) method was proposed by TWI. Because FSW is a solid state welding method, the peak temperature reached during FSW welding is lower than the traditional welding

  7. Recent Advances in Friction Stir Welding Process, Weldment Structure and Properties

    E-Print Network [OSTI]

    Cambridge, University of

    Recent Advances in Friction Stir Welding ­ Process, Weldment Structure and Properties R. Nandan, T University of Cambridge, Cambridge CB2 3QZ, U.K. Abstract Friction stir welding is a refreshing approach flow during welding, elements of tool design, understanding defect formation and the structure

  8. Critical assessment: friction stir welding of H. K. D. H. Bhadeshia*1

    E-Print Network [OSTI]

    Cambridge, University of

    Critical assessment: friction stir welding of steels H. K. D. H. Bhadeshia*1 and T. DebRoy2 The level of activity in research on the friction stir welding of steels is dwarfed when compared of Welding and Joining is to assess the state of the art, focusing on the knowledge base in the open

  9. Modeling of AA5083 Material-Microstructure Evolution During Butt Friction-Stir Welding

    E-Print Network [OSTI]

    Grujicic, Mica

    Modeling of AA5083 Material-Microstructure Evolution During Butt Friction-Stir Welding M. Grujicic yet a fairly comprehensive overview of the friction stir welding (FSW) process is provided-element procedure developed in our prior study. Particular attention is given to proper modeling of the welding work

  10. PublishedbyManeyPublishing(c)IOMCommunicationsLtd Friction stir welding of dissimilar alloys a

    E-Print Network [OSTI]

    Cambridge, University of

    PublishedbyManeyPublishing(c)IOMCommunicationsLtd Friction stir welding of dissimilar alloys ­ a perspective T. DebRoy*1 and H. K. D. H. Bhadeshia2 Friction stir welding does not involve bulk melting. The purpose of this special issue of Science and Technology of Welding and Joining was to assess the status

  11. Modifications in the AA5083 Johnson-Cook Material Model for Use in Friction Stir Welding

    E-Print Network [OSTI]

    Grujicic, Mica

    Modifications in the AA5083 Johnson-Cook Material Model for Use in Friction Stir Welding, material microstructure and properties in friction stir welding welds of AA5083 (a non welding, Johnson-Cook material model 1. Introduction In this study, an attempt is made to modify

  12. Process Modeling of Ti-6Al-4V Linear Friction Welding (LFW)

    E-Print Network [OSTI]

    Grujicic, Mica

    Process Modeling of Ti-6Al-4V Linear Friction Welding (LFW) Mica Grujicic, G. Arakere, B finite-element analysis of the linear friction welding (LFW) process is combined with the basic physical in the open literature revealed that the weld region consists of a thermo- mechanically affected zone (TMAZ

  13. Nonlinear shear wave interaction at a frictional interface: Energy dissipation and generation of harmonics

    E-Print Network [OSTI]

    Norris, Andrew

    Nonlinear shear wave interaction at a frictional interface: Energy dissipation and generation solids, brought into frictional contact by remote normal compression. A shear wave, either time har the partition of energy resulting from a time harmonic obliquely incident plane SH wave reflected and refracted

  14. High-resolution friction force microscopy under electrochemical control Aleksander Labuda,1

    E-Print Network [OSTI]

    Grütter, Peter

    High-resolution friction force microscopy under electrochemical control Aleksander Labuda,1 William and development of a friction force microscope for high-resolution studies in electrochemical environments in liquids. The noise of the system is analyzed based on a methodology for the quantification of all

  15. A phenomenological model to describe turbulent friction in permeable-wall flows

    E-Print Network [OSTI]

    Katul, Gabriel

    A phenomenological model to describe turbulent friction in permeable-wall flows C. Manes,1 L impermeable rough boundaries. A novel phenomenological model that describes such anomalous behavior), A phenomenological model to describe tur- bulent friction in permeable-wall flows, Geophys. Res. Lett., 39, L14403

  16. Energy Production, Frictional Dissipation, and Maximum Intensity of a Numerically Simulated Tropical Cyclone

    E-Print Network [OSTI]

    Wang, Yuqing

    0 Energy Production, Frictional Dissipation, and Maximum Intensity of a Numerically Simulated) viewed as a heat engine converts heat energy extracted from the ocean to kinetic energy of the TC, which is eventually dissipated due to surface friction. Since the energy production rate is a linear function while

  17. Energy Production, Frictional Dissipation, and Maximum Intensity of a Numerically Simulated Tropical Cyclone*

    E-Print Network [OSTI]

    Wang, Yuqing

    Energy Production, Frictional Dissipation, and Maximum Intensity of a Numerically Simulated as a heat engine converts heat energy extracted from the ocean into the kinetic energy of the TC, which is eventually dissipated due to surface friction. Since the energy production rate is a linear function while

  18. Mass/ Inertia and Joint Friction Minimization for a Lowforce Fivedof Haptic Device*

    E-Print Network [OSTI]

    Papadopoulos, Evangelos

    Mass/ Inertia and Joint Friction Minimization for a Low­force Five­dof Haptic Device* Kostas and joint friction for a low ­ force five ­ dof haptic device. The haptic device is optimized along a typical path with proper tolerances, rather than at some workspace operating point. The device, part

  19. Looping and reconfiguration dynamics of a flexible chain with internal friction

    E-Print Network [OSTI]

    Nairhita Samanta; Jayanta Ghosh; Rajarshi Chakrabarti

    2014-04-09T23:59:59.000Z

    In recent past, experiments and simulations have suggested that apart from the solvent friction, friction arising from the protein itself plays an important role in protein folding by affecting the intra-chain loop formation dynamics. This friction is termed as internal friction in the literature. Using a flexible Gaussian chain with internal friction we analyze the intra- chain reconfiguration and loop formation times for all three topology classes namely end-to- end, end-to-interior and interior-to-interior. In a nutshell, bypassing expensive simulations we show how simple models like that of Rouse and Zimm can support the single molecule experiment and computer simulation results on intra-chain diffusion coefficients, looping time and even can predict the effects of tail length on the looping time.

  20. Friction Stir Welding of Mild Steel -Tool Durability and Steel Microstructure , H. K. D. H. Bhadeshia2

    E-Print Network [OSTI]

    Cambridge, University of

    1" " Friction Stir Welding of Mild Steel - Tool Durability and Steel Microstructure A. De1 , H. K in the context of welding difficult aluminium alloys. We now apply this scheme to the friction stir welding and the consequences on the physical metallurgy of the steel. Introduction Friction stir welding (FSW) of aluminium

  1. Role of friction in pattern formation in oscillated granular layers Sung Joon Moon, # J. B. Swift, and Harry L. Swinney

    E-Print Network [OSTI]

    Texas at Austin. University of

    Role of friction in pattern formation in oscillated granular layers Sung Joon Moon, # J. B. Swift grains. Our molecular dynamics simu­ lations reveal that friction is essential for realistic modeling at a container acceleration about 30% smaller than that observed in experiments and simulations with friction

  2. Friction anisotropy at Ni,,100...,,100... interfaces: Molecular dynamics studies Yue Qi and Yang-Tse Cheng

    E-Print Network [OSTI]

    Goddard III, William A.

    Friction anisotropy at Ni,,100...Ã?,,100... interfaces: Molecular dynamics studies Yue Qi and Yang of Technology, Pasadena, California, 91125 Received 8 March 2002; published 30 August 2002 The friction theories predict that most perfect clean incommensurate interfaces would produce no static friction

  3. Friction-induced vibration of a lubricated mechanical system J-J. Sinou*, J. Cayer-Barrioz and H. Berro

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Friction-induced vibration of a lubricated mechanical system J-J. Sinou*, J. Cayer-Barrioz and H that incorporates realistic laws of local friction issued from previous experimental results. The objective or by themselves, such as friction-induced vibrations. In all cases, these vibrations are hardly controllable

  4. A LuGre Tire Friction Model with Exact Aggregate Dynamics Panagiotis Tsiotras, Efstathios Velenis and Michel Sorine

    E-Print Network [OSTI]

    Tsiotras, Panagiotis

    A LuGre Tire Friction Model with Exact Aggregate Dynamics Panagiotis Tsiotras, Efstathios Velenis and Michel Sorine Abstract-- The LuGre dynamic point contact friction model for the two-dimensional translation of a body on a surface has been used in the past to derive a model for the friction forces

  5. Role of friction in pattern formation in oscillated granular layers Sung Joon Moon,* J. B. Swift, and Harry L. Swinney

    E-Print Network [OSTI]

    Texas at Austin. University of

    Role of friction in pattern formation in oscillated granular layers Sung Joon Moon,* J. B. Swift as there are no elastic grains. Our molecular dynamics simulations reveal that friction is essential for realistic with friction. More importantly, even though square and hexagonal patterns form for a wide range

  6. Friction Stir Welding Download the files fswss.txt and fswdyn.txt from the course website. These files contain

    E-Print Network [OSTI]

    Landers, Robert G.

    Friction Stir Welding QUESTION 1 Download the files fswss.txt and fswdyn.txt from the course website. These files contain experimental data from a friction stir welding process of 6061 aluminum 0 2 1 0 F z b z b d z z a z a + = + + (3) #12;Friction Stir Welding QUESTION 2 Download the files

  7. October 14 WA Division Newsletter Page 4 Tool durability and steel microstructure in friction stir welding of mild steel

    E-Print Network [OSTI]

    Cambridge, University of

    scheme to assess tool durability and tool life in the friction stir welding (FSW) of difficult alumin referencing is freely avail- able at: http://tinyurl.com/mst-fsw. Tools for friction stir welding (FSWOctober 14 WA Division Newsletter Page 4 Tool durability and steel microstructure in friction stir

  8. Magnesium and Copper (II) Chloride: A Curious Redox Reaction .

    E-Print Network [OSTI]

    Mannard, Moira

    2014-01-01T23:59:59.000Z

    ??The focus of this research is to follow the oxidation-reduction reaction of solid magnesium metal and an aqueous solution of copper (II) chloride (CuCl2), both… (more)

  9. Energy conversion device and method of reducing friction therein

    DOE Patents [OSTI]

    Solovyeva, Lyudmila Mikhaylovna; Jansson, Kyle S; Elmoursi, Alaa AbdelAzim; Zhu, Dong; Milner, Robert; Daughterty, Early Eugene; Higdon, Clifton Baxter; Elagamy, Kamel Abdel-Khalik; Hicks, Aaron Michael

    2013-10-08T23:59:59.000Z

    A device configured for converting energy includes a first surface, a second surface configured for moving with respect to the first surface during operation of the device, and a coating disposed on at least one of the first surface and the second surface. The coating includes a first layer of a ceramic alloy represented by the general formula AlMgB.sub.14--X, wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of the ceramic alloy and is a doping agent selected from the group of Group IV elements and borides and nitrides thereof, and a second layer disposed on the first layer and including carbon in a gradient concentration. The coating has a hardness of from 10 to 20 GPa and a coefficient of friction of less than or equal to 0.12.

  10. Dynamical friction of radio galaxies in galaxy clusters

    E-Print Network [OSTI]

    Biman B. Nath

    2008-04-22T23:59:59.000Z

    The distribution of luminous radio galaxies in galaxy clusters has been observed to be concentrated in the inner region. We consider the role of dynamical friction of massive galaxies ($M\\sim 10^{12.5}$ M$_{\\odot}$), assuming them to be hosts of luminous radio galaxies, and show that beginning with a Navarro-Frenk-White density profile of a cluster of mass $M_{cl}\\sim 10^{15}$ M$_{\\odot}$ of concentration $c\\sim 5$ and collapsing at $z\\sim 1$, the density profile of radio galaxies evolve to a profile of concentration $c \\sim 25$, as observed, in a time scale of $t\\sim 3\\hbox{--}5$ Gyr.

  11. Lateral vibration effects in atomic-scale friction

    SciTech Connect (OSTI)

    Roth, R. [Climate and Environment Physics, Physics Institute, University of Bern, Bern (Switzerland); Oeschger Centre for Climate Change Research, University of Bern, Bern (Switzerland); Fajardo, O. Y.; Mazo, J. J. [Departamento de Física de la Materia Condensada and Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain); Meyer, E. [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland); Gnecco, E. [Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, 28049 Madrid (Spain)

    2014-02-24T23:59:59.000Z

    The influence of lateral vibrations on the stick-slip motion of a nanotip elastically pulled on a flat crystal surface is studied by atomic force microscopy measurements on a NaCl(001) surface in ultra-high vacuum. The slippage of the nanotip across the crystal lattice is anticipated at increasing driving amplitude, similarly to what is observed in presence of normal vibrations. This lowers the average friction force, as explained by the Prandtl-Tomlinson model with lateral vibrations superimposed at finite temperature. Nevertheless, the peak values of the lateral force, and the total energy losses, are expected to increase with the excitation amplitude, which may limit the practical relevance of this effect.

  12. Single-friction-surface triboelectric generator with human body conduit

    SciTech Connect (OSTI)

    Meng, Bo; Cheng, Xiaoliang; Zhang, Xiaosheng; Han, Mengdi; Liu, Wen; Zhang, Haixia, E-mail: zhang-alice@pku.edu.cn [National Key Lab of Nano/Micro Fabrication Technology, Peking University, Beijing 100871 (China)] [National Key Lab of Nano/Micro Fabrication Technology, Peking University, Beijing 100871 (China)

    2014-03-10T23:59:59.000Z

    We present a transparent single-friction-surface triboelectric generator (STEG) employing human body as the conduit, making the applications of STEG in portable electronics much more practical and leading to a significant output improvement. The STEG with micro-patterned polydimethylsiloxane surface achieved an output voltage of over 200 V with a current density of 4.7 ?A/cm{sup 2}. With human body conduit, the output current increased by 39% and the amount of charge that transferred increased by 34% compared to the results with grounded electrode. A larger increment of 210% and 81% was obtained in the case of STEG with a large-size flat polyethylene terephthalate surface.

  13. Lateral position detection and control for friction stir systems

    DOE Patents [OSTI]

    Fleming, Paul (Boulder, CO); Lammlein, David H. (Houston, TX); Cook, George E. (Brentwood, TN); Wilkes, Don Mitchell (Nashville, TN); Strauss, Alvin M. (Nashville, TN); Delapp, David R. (Ashland City, TN); Hartman, Daniel A. (Fairhope, AL)

    2011-11-08T23:59:59.000Z

    Friction stir methods are disclosed for processing at least one workpiece using a rotary tool with rotating member for contacting and processing the workpiece. The methods include oscillating the rotary tool laterally with respect to a selected propagation path for the rotating member with respect to the workpiece to define an oscillation path for the rotating member. The methods further include obtaining force signals or parameters related to the force experienced by the rotary tool at least while the rotating member is disposed at the extremes of the oscillation. The force signals or parameters associated with the extremes can then be analyzed to determine a lateral position of the selected path with respect to a target path and a lateral offset value can be determined based on the lateral position. The lateral distance between the selected path and the target path can be decreased based on the lateral offset value.

  14. REDUCTIONS WITHOUT REGRET: HISTORICAL PERSPECTIVES

    SciTech Connect (OSTI)

    Swegle, J.; Tincher, D.

    2013-09-09T23:59:59.000Z

    This is the first of three papers (in addition to an introductory summary) aimed at providing a framework for evaluating future reductions or modifications of the U.S. nuclear force, first by considering previous instances in which nuclear-force capabilities were eliminated; second by looking forward into at least the foreseeable future at the features of global and regional deterrence (recognizing that new weapon systems currently projected will have expected lifetimes stretching beyond our ability to predict the future); and third by providing examples of past or possible undesirable outcomes in the shaping of the future nuclear force, as well as some closing thoughts for the future. This paper examines the circumstances and consequences of the elimination of ? The INF-range Pershing II ballistic missile and Gryphon Ground-Launched Cruise Missile (GLCM), deployed by NATO under a dual-track strategy to counter Soviet intermediate-range missiles while pursuing negotiations to limit or eliminate all of these missiles. ? The Short-Range Attack Missile (SRAM), which was actually a family of missiles including SRAM A, SRAM B (never deployed), and SRAM II and SRAM T, these last two cancelled during an over-budget/behind-schedule development phase as part of the Presidential Nuclear Initiatives of 1991 and 1992. ? The nuclear-armed version of the Tomahawk Land-Attack Cruise Missile (TLAM/N), first limited to shore-based storage by the PNIs, and finally eliminated in deliberations surrounding the 2010 Nuclear Posture Review Report. ? The Missile-X (MX), or Peacekeeper, a heavy MIRVed ICBM, deployed in fixed silos, rather than in an originally proposed mobile mode. Peacekeeper was likely intended as a bargaining chip to facilitate elimination of Russian heavy missiles. The plan failed when START II did not enter into force, and the missiles were eliminated at the end of their intended service life. ? The Small ICBM (SICBM), or Midgetman, a road-mobile, single-warhead missile for which per-unit costs were climbing when it was eliminated under the PNIs. Although there were liabilities associated with each of these systems, there were also unique capabilities; this paper lays out the pros and cons for each. Further, we articulate the capabilities that were eliminated with these systems.

  15. REDUCTIONS WITHOUT REGRET: SUMMARY

    SciTech Connect (OSTI)

    Swegle, J.; Tincher, D.

    2013-09-16T23:59:59.000Z

    This paper briefly summarizes the series in which we consider the possibilities for losing, or compromising, key capabilities of the U.S. nuclear force in the face of modernization and reductions. The first of the three papers takes an historical perspective, considering capabilities that were eliminated in past force reductions. The second paper is our attempt to define the needed capabilities looking forward in the context of the current framework for force modernization and the current picture of the evolving challenges of deterrence and assurance. The third paper then provides an example for each of our undesirable outcomes: the creation of roach motels, box canyons, and wrong turns.

  16. Pertechnetate (TcO4-) reduction by reactive ferrous iron forms...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The speciation of redox product Tc(IV) was not affected by reduction rate or Fe(II) mineralogy. Citation: Peretyazhko T, JM Zachara, RK Kukkadapu, SM Heald, IV Kutnyakov, CT...

  17. Kron Reduction of Graphs with Applications to Electrical Networks

    E-Print Network [OSTI]

    Bullo, Francesco

    1 Kron Reduction of Graphs with Applications to Electrical Networks Florian D¨orfler Francesco work supported by NSF grants IIS- 0904501 and CPS-1135819. Florian D¨orfler and Francesco Bullo Barbara, CA 93106, {dorfler, bullo}@engineering.ucsb.edu we consider the circuit naturally associated

  18. PLAINS CO2 REDUCTION PARTNERSHIP

    SciTech Connect (OSTI)

    Edward N. Steadman; John A. Harju; Erin M. O'Leary; James A. Sorensen; Daniel J. Daly; Melanie D. Jensen; Lisa S. Botnen

    2005-07-01T23:59:59.000Z

    The Plains CO{sub 2} Reduction (PCOR) Partnership characterization work is nearing completion, and most remaining efforts are related to finalizing work products. Task 2 (Technology Deployment) has developed a Topical Report entitled ''Deployment Issues Related to Geologic CO{sub 2} Sequestration in the PCOR Partnership Region''. Task 3 (Public Outreach) has developed an informational Public Television program entitled ''Nature in the Balance'', about CO{sub 2} sequestration. The program was completed and aired on Prairie Public Television in this quarter. Task 4 (Sources, Sinks, and Infrastructure) efforts are nearing completion, and data regarding CO{sub 2} sources and sinks and data on the performance and costs for CO{sub 2} separation, capture, treatment, and compression for pipeline transportation are being incorporated into a series of topical reports. The expansion of the Decision Support System Geographic Information System database has continued with the development of a ''save bookmark'' feature that allows users to save a map from the system easily. A feature that allows users to develop a report that summarizes CO{sub 2} sequestration parameters was also developed. Task 5 (Modeling and Phase II Action Plans) focused on screening and qualitatively assessing sequestration options and developing economic estimates for important regional CO{sub 2} sequestration strategies.

  19. Economics of Grade Reduction

    E-Print Network [OSTI]

    Neff, Paul J.

    1914-02-10T23:59:59.000Z

    A Study of the General Principles of the Economics to Be Effected By the Reduction of Grades, the Elimination of Rise and Fall and Curvature, and the Bettering of the Other Physical Condition on the ST. Louis & San Francisco Railroad Lines....

  20. Global Threat Reduction Initiative

    E-Print Network [OSTI]

    Kemner, Ken

    Global Threat Reduction Initiative ­ Conversion Program: Reduced Enrichment for Research and Test the dual application of splitting the atom, U.S. policy towards civilian use of highly enriched uranium and test reactors fueled first with low enriched uranium (LEU) and then later with HEU. By the early 1970s

  1. A frictional model of a two-port unbounded ocean basin

    E-Print Network [OSTI]

    Wert, Richard Thomas

    1968-01-01T23:59:59.000Z

    A FRICTIONAL MODEL OF A TWO-PORT UNBOUNDED OCEAN BASIN A Thesis by RICHARD T. WERT Submitted to the Graduate College of the Texas AE M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1968 Major... Subject: Physical Oceanography A FRICTIONAL MODEL OF A TWO-PORT UNBOUNDED OCEAN BASIN A Thesis by RICHARD T. WERT Approved as to style and content by: (Chairxnan of Coxnxnittee) (Head of the Departxnent) (M her) (Mexnber) May 1968 A Frictional...

  2. Ultra low friction carbon/carbon composites for extreme temperature applications

    DOE Patents [OSTI]

    Erdemir, Ali (Naperville, IL); Busch, Donald E. (Hinsdale, IL); Fenske, George R. (Downers Grove, IL); Lee, Sam (Gardena, CA); Shepherd, Gary (Los Alamitos, CA); Pruett, Gary J. (Cypress, CA)

    2001-01-01T23:59:59.000Z

    A carbon/carbon composite in which a carbon matrix containing a controlled amount of boron or a boron compound is reinforced with carbon fiber exhibits a low coefficient of friction, i.e., on the order of 0.04 to 0.1 at temperatures up to 600.degree. C., which is one of the lowest frictional coefficients for any type of carbonaceous material, including graphite, glassy carbon, diamond, diamond-like carbon and other forms of carbon material. The high degree of slipperiness of the carbon composite renders it particularly adapted for limiting friction and wear at elevated temperatures such as in seals, bearings, shafts, and flexible joints

  3. Shrinking binary and planetary orbits by Kozai cycles with tidal friction

    E-Print Network [OSTI]

    Daniel Fabrycky; Scott Tremaine

    2007-05-30T23:59:59.000Z

    At least two arguments suggest that the orbits of a large fraction of binary stars and extrasolar planets shrank by 1-2 orders of magnitude after formation: (i) the physical radius of a star shrinks by a large factor from birth to the main sequence, yet many main-sequence stars have companions orbiting only a few stellar radii away, and (ii) in current theories of planet formation, the region within ~0.1 AU of a protostar is too hot and rarefied for a Jupiter-mass planet to form, yet many "hot Jupiters" are observed at such distances. We investigate orbital shrinkage by the combined effects of secular perturbations from a distant companion star (Kozai oscillations) and tidal friction. We integrate the relevant equations of motion to predict the distribution of orbital elements produced by this process. Binary stars with orbital periods of 0.1 to 10 days, with a median of ~2 d, are produced from binaries with much longer periods (10 d to 10^5 d), consistent with observations indicating that most or all short-period binaries have distant companions (tertiaries). We also make two new testable predictions: (1) For periods between 3 and 10 d, the distribution of the mutual inclination between the inner binary and the tertiary orbit should peak strongly near 40 deg and 140 deg. (2) Extrasolar planets whose host stars have a distant binary companion may also undergo this process, in which case the orbit of the resulting hot Jupiter will typically be misaligned with the equator of its host star.

  4. Friction Makes the World Go Round Even though there are many physical things that make everyday life possible, few are more important than

    E-Print Network [OSTI]

    Roy, Subrata

    Friction Makes the World Go Round K.G. Rowe Even though there are many physical things that make everyday life possible, few are more important than friction. Friction allows us to walk, drive cars or drive on really slick ice--this would be the case in a world without friction. The Study of Tire Rubber

  5. INVESTIGACI ON REVISTA MEXICANA DE FISICA 52 (5) 444452 OCTUBRE 2006 Reduction of friction in fluid transport: experimental investigation

    E-Print Network [OSTI]

    Aguilar, Guillermo

    ) mediante el uso de soluciones polim´ericas o surfactantes es sin duda alguna la t´ecnica de reducci´on de

  6. Experimental investigation of energy dissipation behavior of the modified friction device

    E-Print Network [OSTI]

    Zahner, Robert Marne

    2011-01-01T23:59:59.000Z

    As building materials become stronger, dynamic design and structural control are effective means of improving serviceability in the future's ever lighter structures. The recently proposed modified friction device (MFD) ...

  7. Complex Non-Linear Modal Analysis for Mechanical Systems: Application to Turbomachinery Bladings With Friction

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Complex Non-Linear Modal Analysis for Mechanical Systems: Application to Turbomachinery Bladings of a turbomachinery blade, with dry-friction interfaces is proposed. In the latter, an original framework

  8. Micro and nano mechanics of materials response during instrumented frictional sliding

    E-Print Network [OSTI]

    Bellemare, Simon C. (Simon Claude)

    2006-01-01T23:59:59.000Z

    Over the past decade, many computational studies have explored the mechanics of instrumented normal indentation. In contrast, very few studies have investigated quantitative aspects of frictional sliding contact in the ...

  9. The Role of Friction Stir Welding in Nuclear Fuel Plate Fabrication

    SciTech Connect (OSTI)

    D Burkes; P Medvedev; M Chapple; A Amritkar; P Wells; I Charit

    2009-02-01T23:59:59.000Z

    The friction bonding process combines desirable attributes of both friction stir welding and friction stir processing. The development of the process is spurred on by the need to fabricate thin, high density, reduced enrichment fuel plates for nuclear research reactors. The work seeks to convert research and test reactors currently operating on highly enriched uranium fuel to operate on low enriched uranium fuel without significant loss in reactor performance, safety characteristics, or significant increase in cost. In doing so, the threat of global nuclear material proliferation will be reduced. Feasibility studies performed on the process show that this is a viable option for mass production of plate-type nuclear fuel. Adapting the friction stir weld process for nuclear fuel fabrication has resulted in the development of several unique ideas and observations. Preliminary results of this adaptation and process model development are discussed.

  10. Defining the role of elastic lubricants and micro textured surfaces in lubricated, sliding friction

    E-Print Network [OSTI]

    Hupp, Sara J. (Sara Jean), 1979-

    2008-01-01T23:59:59.000Z

    Solutions for reducing friction in sliding, lubricated systems include modifying lubricant rheology using polymers and adding a micro-scale texture to the sliding surfaces, but the mechanism of how lubrication properties ...

  11. Forced Response Analysis of Integrally Bladed Disks with Friction Ring Dampers

    E-Print Network [OSTI]

    Boyer, Edmond

    is proposed. In numerical applications, a representative compressor blisk featuring several rings the wheel of blisks. These are held in contact with the blisk due to centrifugal loads and friction

  12. Experimental and Theoretical Investigations of Lube Oil Performance and Engine Friction.

    E-Print Network [OSTI]

    Rohr, William Fredrick

    2013-01-01T23:59:59.000Z

    ??The feasibility of using a motored small, single-cylinder 517 cc Hatz 1D50 diesel engine to evaluate lube oil performance and engine friction at conditions typical… (more)

  13. Friction and Adhesion Forces of Bacillus thuringiensis Spores on Planar Surfaces in Atmospheric Systems

    SciTech Connect (OSTI)

    Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

    2011-01-01T23:59:59.000Z

    The kinetic friction force and the adhesion force of Bacillus thuringiensis spores on planar surfaces in atmospheric systems were studied using atomic force microscopy. The influence of relative humidity (RH) on these forces varied for different surface properties including hydrophobicity, roughness, and surface charge. The friction force of the spore was greater on a rougher surface than on mica, which is atomically flat. As RH increases, the friction force of the spores decreases on mica whereas it increases on rough surfaces. The influence of RH on the interaction forces between hydrophobic surfaces is not as strong as for hydrophilic surfaces. The friction force of the spore is linear to the sum of the adhesion force and normal load on the hydrophobic surface. The poorly defined surface structure of the spore and the adsorption of contaminants from the surrounding atmosphere are believed to cause a discrepancy between the calculated and measured adhesion forces.

  14. Experimental study of friction noise of dry contact under light load

    E-Print Network [OSTI]

    Le-Bot, Alain

    musical instruments such as violins, guitars, sound radiated by glass when rubbing a moist finger, tyres on frictional sound may also be mentioned (Othman et al., 1990-1) and an original device for measuring

  15. Aluminum reduction cell electrode

    DOE Patents [OSTI]

    Goodnow, W.H.; Payne, J.R.

    1982-09-14T23:59:59.000Z

    The invention is directed to cathode modules comprised of refractory hard metal materials, such as TiB[sub 2], for an electrolytic cell for the reduction of alumina wherein the modules may be installed and replaced during operation of the cell and wherein the structure of the cathode modules is such that the refractory hard metal materials are not subjected to externally applied forces or rigid constraints. 9 figs.

  16. Friction stir welding and processing of oxide dispersion strengthened (ODS) alloys

    DOE Patents [OSTI]

    Ren, Weiju

    2014-11-11T23:59:59.000Z

    A method of welding including forming a filler material of a first oxide dispersoid metal, the first oxide dispersoid material having first strengthening particles that compensate for decreases in weld strength of friction stir welded oxide dispersoid metals; positioning the filler material between a first metal structure and a second metal structure each being comprised of at least a second oxide dispersoid metal; and friction welding the filler material, the first metal structure and the second metal structure to provide a weld.

  17. Hard and low friction nitride coatings and methods for forming the same

    DOE Patents [OSTI]

    Erdemir, Ali (Naperville, IL); Urgen, Mustafa (Istanbul, TR); Cakir, Ali Fuat (Istanbul, TR); Eryilmaz, Osman Levent (Bolingbrook, IL); Kazmanli, Kursat (Istanbul, TR); Keles, Ozgul (Istanbul, TR)

    2007-05-01T23:59:59.000Z

    An improved coating material possessing super-hard and low friction properties and a method for forming the same. The improved coating material includes the use of a noble metal or soft metal homogeneously distributed within a hard nitride material. The addition of small amounts of such metals into nitrides such as molybdenum nitride, titanium nitride, and chromium nitride results in as much as increasing of the hardness of the material as well as decreasing the friction coefficient and increasing the oxidation resistance.

  18. Stellite 6 Friction Changes Due to Aging and In-Service Testing

    SciTech Connect (OSTI)

    Watkins, John Clifford; DeWall, Kevin George

    2001-07-01T23:59:59.000Z

    For the past several years, researchers at the Idaho National Engineering and Environmental Laboratory, under the sponsorship of the U.S. Nuclear Regulatory Commission, have been investigating the ability of motor-operated valves to close or open when subjected to design basis flow and pressure loads. Part of this research addresses the friction that occurs at the interface between the valve disc and the valve body seats during operation of a gate valve. In most gate valves, these surfaces are hardfaced with Stellite 6, a cobalt-based alloy. The nuclear industry has developed methods to analytically predict the thrust needed to operate these valves at specific pressure conditions. To produce accurate valve thrust predictions; the analyst must have a reasonably accurate, though conservative, estimate of the coefficient of friction at the disc-to-seat interface. One of the questions that remains to be answered is whether, and to what extent, aging of the disc and seat surfaces affects the disc-to-seat coefficient of friction. Specifically, does the accumulation of a surface film due to aging of these surfaces increase the coefficient of friction and if so, how much? This paper presents results of specimen tests addressing this issue with emphasis on the following: • The change in the friction coefficient of Stellite 6 as it ages and whether the friction reaches a plateau. • The effect periodic gate valve cycling due to in-service testing has on the friction coefficient. • The results of an independent review of the test methods, processes, and the results of the research to date. • The status of ongoing aging and friction testing.

  19. Friction coefficients of sorghum grain on steel, teflon, and concrete surfaces

    E-Print Network [OSTI]

    Hossain, Quazi A

    1967-01-01T23:59:59.000Z

    FRICTION COEFFICIENTS OF SORGHUM GRAIN ON STEEL, TEFLON, AND CONCRETE SURFACES A Thesis By QUAZI ANWAR HOSSAIN Submitted to the Graduate College of the Texas A6M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE January 1967 Major Subject: Agricultural Engineering FRICTION COEFFICIENTS OF SORGHUM GRMN ON STEEL, TEFLON, AND CONCRETE SURFACES A Thesis By QUAZI ANWAR HOSSAIN Approved as to style and content by: (Chairma Com ' ee) ead o D'epart nt...

  20. A mechanistic study of proton reduction catalyzed by a pentapyridine cobalt complex: evidence for

    E-Print Network [OSTI]

    -limited conditions in acetonitrile with acetic acid as the proton donor. Two pathways for proton reduction are identified via cyclic voltammetry: one pathway occurring from an acetonitrile-bound CoII/I couple measurements further suggest that the onset of catalysis from the acetonitrile-bound CoII/I couple is highly

  1. Electric force microscopy of semiconductors: Theory of cantilever frequency fluctuations and noncontact friction

    SciTech Connect (OSTI)

    Lekkala, Swapna; Marohn, John A.; Loring, Roger F., E-mail: roger.loring@cornell.edu [Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States)

    2013-11-14T23:59:59.000Z

    An electric force microscope employs a charged atomic force microscope probe in vacuum to measure fluctuating electric forces above the sample surface generated by dynamics of molecules and charge carriers. We present a theoretical description of two observables in electric force microscopy of a semiconductor: the spectral density of cantilever frequency fluctuations (jitter), which are associated with low-frequency dynamics in the sample, and the coefficient of noncontact friction, induced by higher-frequency motions. The treatment is classical-mechanical, based on linear response theory and classical electrodynamics of diffusing charges in a dielectric continuum. Calculations of frequency jitter explain the absence of contributions from carrier dynamics to previous measurements of an organic field effect transistor. Calculations of noncontact friction predict decreasing friction with increasing carrier density through the suppression of carrier density fluctuations by intercarrier Coulomb interactions. The predicted carrier density dependence of the friction coefficient is consistent with measurements of the dopant density dependence of noncontact friction over Si. Our calculations predict that in contrast to the measurement of cantilever frequency jitter, a noncontact friction measurement over an organic semiconductor could show appreciable contributions from charge carriers.

  2. Enhancing trappable antiproton populations through deceleration and frictional cooling

    SciTech Connect (OSTI)

    Zolotorev, Max; Sessler, Andrew; Penn, Gregory; Wurtele, Jonathan S.; Charman, Andrew E.

    2012-03-20T23:59:59.000Z

    CERN currently delivers antiprotons for trapping experiments with the Antiproton Decelerator (AD), which slows the antiprotons down to about 5 MeV.This energy is currently too high for direct trapping, and thick foils are used to slow down the beam to energies which can be trapped.To allow further deceleration to $\\sim 100 \\;\\mbox{keV}$, CERN is initiating the construction of ELENA,consisting of a ring which will combine RF deceleration and electron cooling capabilities. We describe a simple frictionalcooling scheme that can serve to provide significantly improved trapping efficiency, either directly from the AD or first usinga standard deceleration mechanism (induction linac or RFQ). This scheme could be implemented in a short time.The device itself is short in length, uses accessible voltages, and at reasonable cost could serve in the interim beforeELENA becomes operational, or possibly in lieu of ELENA for some experiments. Simple theory and simulations provide a preliminary assessment of theconcept and its strengths and limitations, and highlight important areas for experimental studies, in particular to pin down the level of multiplescattering for low-energy antiprotons. We show that the frictional cooling scheme can provide a similar energy spectrum to that of ELENA,but with higher transverse emittances.

  3. Dynamical Friction and Resonance Trapping in Planetary Systems

    E-Print Network [OSTI]

    Nader Haghighipour

    1998-12-05T23:59:59.000Z

    A restricted planar circular three-body system, consisting of the Sun and two planets, is studied as a simple model for a planetary system. The mass of the inner planet is considered to be larger and the system is assumed to be moving in a uniform interplanetary medium with constant density. Numerical integrations of this system indicate a resonance capture when the dynamical friction of the interplanetary medium is taken into account. As a result of this resonance trapping, the ratio of orbital periods of the two planets becomes nearly commensurate and the eccentricity and semimajor axis of the orbit of the outer planet and also its angular momentum and total energy become constant. It appears from the numerical work that the resulting commensurability and also the resonant values of the orbital elements of the outer planet are essentially independent of the initial relative positions of the two bodies. The results of numerical integrations of this system are presented and the first-order partially averaged equations are studied in order to elucidate the behavior of the system while captured in resonance.

  4. Artificial Photosynthesis II -

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    II - Artificial Photosynthesis II - Joint Center for Artificial Photosynthesis (JCAP) Simulations NathanLewis.png Schematic of a photoelectrochemical cell being designed to harness...

  5. Measurement of local internal friction in metallic glasses

    SciTech Connect (OSTI)

    Wagner, H.; Büchsenschütz-Göbeler, M.; Luo, Y.; Samwer, K. [I. Physikalisches Institut, Georg-August Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Kumar, A. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Arnold, W., E-mail: w.arnold@mx.uni-saarland.de [I. Physikalisches Institut, Georg-August Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Department of Materials and Materials Technology, Saarland University, Campus D 2.2, D-66123 Saarbrücken (Germany)

    2014-04-07T23:59:59.000Z

    Atomic force acoustic microscopy (AFAM), an advanced scanning probe microscopy technique, has been used to measure local elastic properties with a spatial resolution given by the tip-sample contact radius. AFAM is based on inducing out-of-plane vibrations in the specimen. The vibrations are sensed by the AFM cantilever from by the photodiode signal when its tip is in contact with the material under test. To measure local damping, the inverse quality factor Q{sup ?1} of the resonance curve is usually evaluated. Here, from the contact-resonance spectra obtained, we determine the real and imaginary part of the contact stiffness k* and from these two quantities the local damping factor Q{sub loc}{sup ?1} is obtained which is proportional to the imaginary part ? of the contact stiffness. The evaluation of the data is based on the cantilever's mass distribution with damped flexural modes and not on an effective point-mass approximation for the cantilever’s motion. The given equation is simple to use and has been employed to study the local Q{sub loc}{sup ?1} of amorphous PdCuSi metallic glass and its crystalline counterpart as a function of position of the AFM tip on the surface. The width of the distribution changes dramatically from the amorphous to the crystalline state as expected from the consequences of the potential-energy landscape picture. The center value of the distribution curve for Q{sub loc}{sup ?1} coincides very well with published data, based on global ultrasonic or internal friction measurements. This is compared to Q{sub loc}{sup ?1} measured in crystalline SrTiO{sub 3}, which exhibits a narrow distribution, as expected.

  6. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect (OSTI)

    Victor W. Wong; Tian Tian; Grant Smedley; Jeffrey Jocsak

    2004-09-30T23:59:59.000Z

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. An iterative process of simulation, experimentation and analysis, are being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various low-friction strategies and ring-design concepts have been explored, and engine experiments have been done on a full-scale Waukesha VGF F18 in-line 6 cylinder power generation engine rated at 370 kW at 1800 rpm. Current accomplishments include designing and testing ring-packs using a subtle top-compression-ring profile (skewed barrel design), lowering the tension of the oil-control ring, employing a negative twist to the scraper ring to control oil consumption. Initial test data indicate that piston ring-pack friction was reduced by 35% by lowering the oil-control ring tension alone, which corresponds to a 1.5% improvement in fuel efficiency. Although small in magnitude, this improvement represents a first step towards anticipated aggregate improvements from other strategies. Other ring-pack design strategies to lower friction have been identified, including reduced axial distance between the top two rings, tilted top-ring groove. Some of these configurations have been tested and some await further evaluation. Colorado State University performed the tests and Waukesha Engine Dresser, Inc. provided technical support. Key elements of the continuing work include optimizing the engine piston design, application of surface and material developments in conjunction with improved lubricant properties, system modeling and analysis, and continued technology demonstration in an actual full-sized reciprocating natural-gas engine.

  7. Aluminum reduction cell electrode

    DOE Patents [OSTI]

    Payne, J.R.

    1983-09-20T23:59:59.000Z

    The invention is directed to an anode-cathode structure for an electrolytic cell for the reduction of alumina wherein the structure is comprised of a carbon anode assembly which straddles a wedge-shaped refractory hard metal cathode assembly having steeply sloped cathodic surfaces, each cathodic surface being paired in essentially parallel planar relationship with an anode surface. The anode-cathode structure not only takes into account the structural weakness of refractory hard metal materials but also permits the changing of the RHM assembly during operation of the cell. Further, the anode-cathode structure enhances the removal of anode gas from the interpolar gap between the anode and cathode surfaces. 10 figs.

  8. Nondestructive, in-process inspection of inertia friction welding : an investigation into a new sensing technique.

    SciTech Connect (OSTI)

    Hartman, D. A. (Daniel A.); Cola, M. J. (Mark J.); Dave, V. R. (Vivek R.); Dozhier, N. G. (Nathan G.); Carpenter, R. W. (Robert W.)

    2002-01-01T23:59:59.000Z

    This paper investigates the capabilities of a new sensor for in-process monitoring of quality during friction welding. The non-contact sensor is composed of microphones that are mounted in an aluminum ring which surrounds the weld joint. The sensor collects the acoustical energy (in the form of sound pressure) that is emitted during the plastic deformation and phase transformations (if applicable) in friction welding processes. The focus in this preliminary investigation is to search for and identify features within the acoustical emission that are indicative of bond quality. Bar-to-bar inertia friction welding (one form of friction welding) of copper to 304L stainless steel is used in this proof-of-concept study. This material combination exhibits only marginal weldability and is ideally suited for validating the capabilities of this new sensing technique. A probabilistic neural network is employed in this work to analyze the acoustical emission's frequency spectrum in an attempt to classify acceptable, conditional, and unacceptable welds. Our preliminary findings indicate that quality-based process features do exist within the frequency spectrum of the acoustical signature. The results from this analysis are presented. Future work in improving the sensing and interpretation of the data is discussed in an effort to develop a robust method of quality-based, in-process monitoring of friction welds.

  9. Special relativity as the limit of an Aristotelian universal friction theory under Reye's assumption

    E-Print Network [OSTI]

    E. Minguzzi

    2014-11-28T23:59:59.000Z

    This work explores a classical mechanical theory under two further assumptions: (a) there is a universal dry friction force (Aristotelian mechanics), and (b) the variation of the mass of a body due to wear is proportional to the work done by the friction force on the body (Reye's hypothesis). It is shown that mass depends on velocity as in Special Relativity, and that the velocity is constant for a particular characteristic value. In the limit of vanishing friction the theory satisfies a relativity principle as bodies do not decelerate and, therefore, the absolute frame becomes unobservable. However, the limit theory is not Newtonian mechanics, with its Galilei group symmetry, but rather Special Relativity. This result suggests to regard Special Relativity as the limit of a theory presenting universal friction and exchange of mass-energy with a reservoir (vacuum). Thus, quite surprisingly, Special Relativity follows from the absolute space (ether) concept and could have been discovered following studies of Aristotelian mechanics and friction. We end the work confronting the full theory with observations. It predicts the Hubble law through tired light, and hence it is incompatible with supernova light curves unless both mechanisms of tired light (locally) and universe expansion (non-locally) are at work. It also nicely accounts for some challenging numerical coincidences involving phenomena under low acceleration.

  10. Evaluation of microstructure and mechanical properties in friction stir processed SKD61 tool steel

    SciTech Connect (OSTI)

    Chen, Y.C., E-mail: armstrong@hit.edu.cn [Joining and Welding Research Institute, Osaka University, Osaka 567-0047 (Japan); Nakata, K. [Joining and Welding Research Institute, Osaka University, Osaka 567-0047 (Japan)

    2009-12-15T23:59:59.000Z

    A SKD61 tool steel was friction stir processed using a polycrystalline cubic boron nitride tool. Microstructure, tensile properties and wear characteristic were evaluated. Fine grains with a martensite structure were produced in the friction stir processed zone, which led to the increase of the microindentation hardness. The grains became finer when the heat input was lowered. The transverse tensile strength of the friction stir processed zone was equal to that of base metal and all the tensile specimens fractured at base metal zone. The wear width and depth of the friction stir processed zone at the load of 1.96 N were 339 {mu}m and 6 {mu}m, as compared to 888 {mu}m and 42 {mu}m of the base metal, decreased by 62% and 86%. Findings of the present study suggest that low heat input is an effective method to produce a friction stir processed zone composed of relatively fine grain martensitic structure with good tensile properties and wear characteristic.

  11. Economic Analysis of Commercial Idling Reduction Technologies...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Technologies: Which idling reduction system is most economical for truck owners? Economic Analysis of Commercial Idling Reduction Technologies: Which idling reduction system...

  12. Dissimilar Friction Stir Welds in Al5186-Al2024: The Effect of Process Parameters on Microstructures and Mechanical Properties

    SciTech Connect (OSTI)

    Mousavi, S. A. A. Akbari; ShamAbadi, S. H. [School of Metallurgy and Materials Engineering, University College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2011-01-17T23:59:59.000Z

    The effect of tool traverse and rotation speeds on the microstructures and mechanical properties are quantified for welds between non-age-hardening Al5083 and age hardening Al2024 and compared to single alloy joints made from each of the two constituents. In this paper, we report the results of microstructural, mechanical property investigations of Al5186-Al2024 friction stir welds produced using various rotations and traveling speeds of the tool to investigate the effects of the welding parameters on the joint strength. Metallographic studies by optical microscopy, electron probe microscopy, and the utilization of the X-ray diffraction technique have been conducted. It was found that the weld properties were dominated by the thermal input rather than the mechanical deformation by the tool. In particular the larger stresses under the weld tool on the AA5186 side compared to the AA2024 side are related to a transient reduction in yield stress due to dissolution of the hardening precipitates during welding prior to natural aging after welding.

  13. Temperature and water vapor pressure effects on the friction coefficient of hydrogenated diamondlike carbon films.

    SciTech Connect (OSTI)

    Dickrell, P. L.; Sawyer, W. G.; Eryilmaz, O. L.; Erdemir, A.; Energy Technology; Univ. of Florida

    2009-07-01T23:59:59.000Z

    Microtribological measurements of a hydrogenated diamondlike carbon film in controlled gaseous environments show that water vapor plays a significant role in the friction coefficient. These experiments reveal an initial high friction transient behavior that does not reoccur even after extended periods of exposure to low partial pressures of H{sub 2}O and O{sub 2}. Experiments varying both water vapor pressure and sample temperature show trends of a decreasing friction coefficient as a function of both the decreasing water vapor pressure and the increasing substrate temperature. Theses trends are examined with regard to first order gas-surface interactions. Model fits give activation energies on the order of 40 kJ/mol, which is consistent with water vapor desorption.

  14. Driven translocation of a polymer: role of pore friction and crowding

    E-Print Network [OSTI]

    Johan L. A. Dubbeldam; V. G. Rostiashvili; T. A. Vilgis

    2014-04-01T23:59:59.000Z

    Force-driven translocation of a macromolecule through a nanopore is investigated by taking into account the monomer-pore friction as well as the "crowding" of monomers on the {\\it trans} - side of the membrane which counterbalance the driving force acting in the pore. The set of governing differential-algebraic equations for the translocation dynamics is derived and solved numerically. The analysis of this solution shows that the crowding of monomers on the trans side hardly affects the dynamics, but the monomer-pore friction can substantially slow down the translocation process. Moreover, the translocation exponent $\\alpha$ in the translocation time - vs. - chain length scaling law, $\\tau \\propto N^{\\alpha}$, becomes smaller when monomer-pore friction coefficient increases. This is most noticeable for relatively strong forces. Our findings may explain the variety of $\\alpha$ values which were found in experiments and computer simulations.

  15. Identification of Friction Parameters from the Inverse Analysis of a Direct Extrusion Test

    SciTech Connect (OSTI)

    Adinel, Gavrus; Thien, Pham Duc [LGCGM Laboratory, EA 3913, INSA de RENNES, UEB, CS70839, F-35708, Rennes-Cedex 7 (France); Henri, Francillette [SCR/CM, UMR 6226, INSA de RENNES, UEB, CS70839, F-35708, Rennes-Cedex 7 (France)

    2011-01-17T23:59:59.000Z

    This work proposes to use a special upsetting test and an optimal direct extrusion one performed to identify the constitutive equation of the material behavior and the friction coefficients directly from the load-stroke curves. The proposed friction test has the advantage to permit to take into account contact phenomena corresponding to new specimen surfaces created during a real bulk cold forming process. A lot of numerical simulations are made with the commercial software FORGE2 in order to study the influence of some design and process parameters. Different friction laws will be identified starting from the classical Coulomb and Tresca ones. All the parameter identifications are made using the Inverse Analysis principle.

  16. Large Wind Property Tax Reduction

    Broader source: Energy.gov [DOE]

    In 2001, North Dakota established property tax reductions for commercial wind turbines constructed before 2011. Originally, the law reduced the taxable value of centrally-assessed* wind turbines...

  17. Nonlinear noise reduction for electrocardiograms

    E-Print Network [OSTI]

    Kaplan, Daniel T.

    Nonlinear noise reduction for electrocardiograms Thomas Schreiber Physics Department, University time series. The underlying physiological process, the electrochemical excitation of cardiac tissue

  18. SCR Technologies for NOx Reduction

    Broader source: Energy.gov (indexed) [DOE]

    SCR Technology for NOx Reduction Outline Necessity of NOx Exhaust Gas Aftertreatment Air-assisted Dosing Systems (HD applications) Field experience with DENOXTRONIC for MDHD...

  19. Assessments of fluid friction factors for use in leak rate calculations

    SciTech Connect (OSTI)

    Chivers, T.C. [Berkeley Technology Centre, Glos (United Kingdom)

    1997-04-01T23:59:59.000Z

    Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.

  20. Casimir Friction in Terms of Moving Harmonic Oscillators: Equivalence Between Two Different Formulations

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2011-01-06T23:59:59.000Z

    The Casimir friction problem can be dealt with in a simplified way by considering two harmonic oscillators moving with constant relative velocity. Recently we calculated the energy dissipation for such a case, [EPL {\\bf 91}, 60003 (2010); Europ. Phys. J. D {\\bf 61}, 335 (2011)]. A recent study of Barton [New J. Phys. {\\bf 12}, 113044 (2010)] seemingly leads to a different result for the dissipation. If such a discrepancy really were true, it would imply a delicate difficulty for the basic theory of Casimir friction. In the present note we show that the expressions for the dissipation are in fact physically equivalent, at T=0.

  1. Friction as a probe of surface properties of a polymer glass

    E-Print Network [OSTI]

    Lionel Bureau

    2007-07-12T23:59:59.000Z

    We probe the temperature dependence of friction at the interface between a glassy poly(methylmethacrylate) lens and a flat substrate coated with a methyl-terminated self-assembled monolayer. The monolayer exhibits density defects which act as pinning sites for the polymer chains. We show that the shear response of such an interface supports the existence, at the surface of the glassy polymer, of a nanometer-thick layer of mobile chains. Friction can be ascribed to the interplay between viscouslike dissipation in this layer and depinning of chains adsorbed on the substrate. We further show that the pinning dynamics is controlled by \\beta rotational motions localized at the interface.

  2. Hydrogen Compression, Storage, and Dispensing Cost Reduction...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Compression, Storage, and Dispensing Cost Reduction Workshop Addendum Hydrogen Compression, Storage, and Dispensing Cost Reduction Workshop Addendum Document states additional...

  3. Contiguous Platinum Monolayer Oxygen Reduction Electrocatalysts...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Contiguous Platinum Monolayer Oxygen Reduction Electrocatalysts on High-Stability-Low-Cost Supports Contiguous Platinum Monolayer Oxygen Reduction Electrocatalysts on...

  4. Development of a Robust and Cost-Effective Friction Stir Welding Process for Use in Advanced Military Vehicles

    E-Print Network [OSTI]

    Grujicic, Mica

    Development of a Robust and Cost-Effective Friction Stir Welding Process for Use in Advanced potential). Unfortu- nately, these alloys are not very amenable to conventional fusion-based welding technologies and in-order to obtain high-quality welds, solid-state joining technologies such as Friction stir

  5. Friction and wear behavior of ultra-high molecular weight polyethylene as a function of polymer crystallinity

    E-Print Network [OSTI]

    Lin, Zhiqun

    Friction and wear behavior of ultra-high molecular weight polyethylene as a function of polymer-grade ultra-high molecular weight polyethylene (UHMWPE) (GUR 1050 resin) were evaluated as a function replacements; Ultra-high molecular weight polyethylene (UHMWPE); Crystallinity; Friction; Wear 1. Introduction

  6. Influence of orographic and canopy conditions on friction velocities observed during frontal events using Doppler sodar observations

    SciTech Connect (OSTI)

    Kotroni, V.; Amory-Mazaudier, C. (CRPE, Saint-Maur des Fosses (France))

    1993-03-01T23:59:59.000Z

    Sodar friction velocities, obtained during frontal events traversing areas characterized by different orographic and canopy conditions (flat, bare ground, small hills and valleys with agricultural crops and trees, agricultural crops and forest on a flat ground, bare ground on the side of a mountain), are compared in order to identify the influence of topography on this parameter. For some case studies, sounding and sodar data are combined in order to provide a relation between the friction velocity and the low-level jet presence. For the cases analyzed in this paper, the following results are obtained: the frontal passage is associated with a decrease of the horizontal wind speed (about 50% in magnitude) in the surface layer, and an increase of the friction velocity before the frontal passage followed by a decrease just at the time of the frontal passage or with a little delay. Friction velocity is more intense in the cold side of the low-level jet and its maximum represents 2% of the low-level jet maximum magnitude. As it concerns the influence of the terrain conditions on friction velocity, mountain effects yield to more intense friction-velocity values and to a superposition of an oscillating behavior on the time variation of friction velocity, while forest effects induce a shift of the frontal signature on the time variation of friction velocity at higher height levels. 25 refs., 18 figs., 3 tabs.

  7. The development of an experimental procedure to determine the amount of active internal friction in a rotor-bearing system

    E-Print Network [OSTI]

    Parker, Jeffrey Scott

    1997-01-01T23:59:59.000Z

    . The logarithmic decrement as calculated by the time response is used to determine the active friction force. By affecting the vibrational mode shape (by the use of weights at each end), the free-free rotor can simulate the frictional characteristics of a rotor...

  8. The Rate-and State-Dependence of Sea Ice Friction Ben Lishman, Peter Sammonds, Daniel Feltham, and Alex Wilchinsky

    E-Print Network [OSTI]

    Feltham, Daniel

    for further work. 2. Experimental programme To produce a quantitative constitutive description of ice frictionPOAC09-66 The Rate- and State- Dependence of Sea Ice Friction Ben Lishman, Peter Sammonds, Daniel Feltham, and Alex Wilchinsky Rock and Ice Physics Laboratory, and Centre for Polar Observation

  9. Development of statistical wet weather model to evaluate frictional properties at the pavement-tire interface on hot mix asphalt concrete

    E-Print Network [OSTI]

    Bedi, Harpreet

    2001-01-01T23:59:59.000Z

    Skid resistance on wet pavements is influenced by friction at the tire-pavement interface as well as overall hot mix asphalt (HMA) performance. It is important to control aggregate, asphalt, and mix properties to achieve desirable frictional...

  10. Livestock Odor Reduction Demonstration Project

    E-Print Network [OSTI]

    Lin, Zhiqun

    Livestock Odor Reduction Demonstration Project Objectives The 1996 and 1997 Iowa General Assembly-share basis to livestock producers and operators selected to carry out various demonstration projects. Organization The Livestock Odor Reduction Demonstration Project was administered by ISU Extension. Stewart

  11. Environmental Sustainability Paper Usage / Reduction

    E-Print Network [OSTI]

    ;carbon footprint and develop carbon reduction projects around IT and staff/student behaviour change is supported by the Environmental Sustainability Manager and is seen as a key link to the University's Carbon Management Programme (e.g. to produce a forecast of carbon reductions as required by the Carbon Trust

  12. Comprehensive Poverty Reduction Strategies in

    E-Print Network [OSTI]

    Peak, Derek

    Comprehensive Poverty Reduction Strategies in Canada: Policy or Window Dressing? Charles Plante, Upstream: Institute for a Healthy Society #12;Overview What is poverty? Current state of poverty in Saskatchewan What is a Comprehensive Poverty Reduction Strategy (CPRS)? Are CPRS effective at reducing

  13. Asymptotic behavior of an elastic satellite with internal friction

    E-Print Network [OSTI]

    Emanuele Haus; Dario Bambusi

    2012-12-04T23:59:59.000Z

    We study the dynamics of an elastic body whose shape and position evolve due to the gravitational forces exerted by a pointlike planet. The main result is that, if all the deformations of the satellite dissipate some energy, then under a suitable nondegeneracy condition there are only three possible outcomes for the dynamics: (i) the orbit of the satellite is unbounded, (ii) the satellite falls on the planet, (iii) the satellite is captured in synchronous resonance i.e. its orbit is asymptotic to a motion in which the barycenter moves on a circular orbit, and the satellite moves rigidly, always showing the same face to the planet. The result is obtained by making use of LaSalle's invariance principle and by a careful kinematic analysis showing that energy stops dissipating only on synchronous orbits. We also use in quite an extensive way the fact that conservative elastodynamics is a Hamiltonian system invariant under the action of the rotation group.

  14. Force microscopy of layering and friction in an ionic liquid Judith Hotha,b

    E-Print Network [OSTI]

    Mueser, Martin

    shape of the force vs. distance curve is explained by a model for the interaction between tip, gold of the compliant force sensor between branches of the oscillatory force curve. Frictional force between-viscosity, yet load- bearing lubricant [1-4]. The load-bearing ability stems from the formation of solvation

  15. Fretting Corrosion Damage of Total Hip Prosthesis: Friction Coefficient and Damage Rate Constant Approach

    E-Print Network [OSTI]

    Boyer, Edmond

    1 Fretting Corrosion Damage of Total Hip Prosthesis: Friction Coefficient and Damage Rate Constant Building, University Park 16802 PA USA 4 Chair Professor Center for Research Excellence in Corrosion hip prosthesis. Fretting corrosion tests were conducted with stainless steel and poly (methyl

  16. Frictional heating and convective cooling of polycrystalline diamond drag tools during rock cutting

    SciTech Connect (OSTI)

    Ortega, A.; Glowka, D.A.

    1982-01-01T23:59:59.000Z

    A numerical-analytical model is developed to predict temperatures in stud-mounted polycrystalline diamond compact (PDC) drag tools during rock cutting. Experimental measurements of the convective heat transfer coefficient for PDC cutters are used in the model to predict temperatures under typical drilling conditions with fluid flow. The analysis compares favorably with measurements of frictional temperatures in controlled cutting tests on Tennessee marble. It is shown that mean cutter wearflat temperatures can be maintained below the critical value of 750{sup 0}C only under conditions of low friction at the cutter/rock interface. This is true, regardless of the level of convective cooling. In fact, a cooling limit is established above which increases in convective cooling do not further reduce cutter temperatures. The ability of liquid drilling fluids to reduce interface friction is thus shown to be far more important in preventing excessive temperatures than their ability to provide cutter cooling. Due to the relatively high interface friction developed under typical air drilling conditions, it is doubtful that temperatures can be kept subcritical at high rotary speeds in some formations when air is employed as the drilling fluid, regardless of the level of cooling achieved.

  17. "Information-Friction" and its implications on minimum energy required for communication

    E-Print Network [OSTI]

    Pulkit Grover

    2014-09-01T23:59:59.000Z

    Just as there are frictional losses associated with moving masses on a surface, what if there were frictional losses associated with moving information on a substrate? Indeed, many modes of communication suffer from such frictional losses. We propose to model these losses as proportional to "bit-meters," i.e., the product of mass of information (i.e., the number of bits) and the distance of information transport. We use this "information- friction" model to understand fundamental energy requirements on encoding and decoding in communication circuitry. First, for communication across a binary input AWGN channel, we arrive at fundamental limits on bit-meters (and thus energy consumption) for decoding implementations that have a predetermined input-independent length of messages. For encoding, we relax the fixed-length assumption and derive bounds for flexible-message- length implementations. Using these lower bounds we show that the total (transmit + encoding + decoding) energy-per-bit must diverge to infinity as the target error probability is lowered to zero. Further, the closer the communication rate is maintained to the channel capacity (as the target error-probability is lowered to zero), the faster the required decoding energy diverges to infinity.

  18. Torsion Spring Oscillator with Dry Friction Summary of the Principal Formulas

    E-Print Network [OSTI]

    Butikov, Eugene

    Torsion Spring Oscillator with Dry Friction ­ Problems Summary of the Principal Formulas of the angle m which sets the limits of the dead zone on both sides of the middle position at which the spring the situation characteris- tic of measuring instruments using a needle, such as moving-coil galvanometers

  19. Modification of boundary lubrication by oil-soluble friction modifier Yingxi Zhua

    E-Print Network [OSTI]

    Granick, Steve

    Modification of boundary lubrication by oil-soluble friction modifier additives Yingxi Zhua in lubricants of the type used at the wet clutch interface in automatic transmissions has been studied using in the boundary lubrication regime and compared to a fully-formulated automatic transmission fluid (ATF). 1

  20. Calibration of the torsional spring constant and the lateral photodiode response of frictional force microscopes

    E-Print Network [OSTI]

    Attard, Phil

    Calibration of the torsional spring constant and the lateral photodiode response of frictional simultaneously calibrates the photodiode response to the angular deflection of the cantilever. It does not rely steps: the calibration of the lateral photodiode response to convert the measured volts to the angle

  1. Analytical and Experimental Study of Annular Two-Phase Flow Friction Pressure Drop Under Microgravity

    E-Print Network [OSTI]

    Nguyen, Ngoc Thanh

    2011-02-22T23:59:59.000Z

    to design reliable two-phase systems. The main objective of this present research is to develop a new mathematical model that can accurately predict the annular two-phase friction pressure drop to optimize the design of two-phase systems. The two-phase flow...

  2. Wear 260 (2006) 12951304 On the friction and wear performance of boric acid lubricant

    E-Print Network [OSTI]

    Sawyer, Wallace

    effective in terms of both friction and wear performance. Based on the success of the combined lubricant experiments, the boric acid was then mixed with canola oil to form a completely natural lubricant combination the undesirable effects of wear, lubricants are generally applied along the interface of contacting materials

  3. Quantitative Model of Price Diffusion and Market Friction Based on Trading as a Mechanistic Random Process

    E-Print Network [OSTI]

    Quantitative Model of Price Diffusion and Market Friction Based on Trading as a Mechanistic Random 2002; published 13 March 2003) We model trading and price formation in a market under the assumption for the most basic properties of markets, such as the diffusion rate of prices (which is the standard measure

  4. Error Estimation And Accurate Mapping Based ALE Formulation For 3D Simulation Of Friction Stir Welding

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Welding Simon Guerdoux, Lionel Fourment* CEMEF, Mines cle Paris, BP 207, 06 904 Sophia Antipolis Ceclex) formulation is developed to simulate the different stages of the Friction Stir Welding (FSW) process standard approaches. The proposed ALE formulation is applied to FSW simulation. Steady state welding

  5. Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

    E-Print Network [OSTI]

    Grujicic, Mica

    Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys M welding (FSW) process are investigated computationally. Within the numerical model of the FSW process component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process

  6. Multiple pass and multiple layer friction stir welding and material enhancement processes

    DOE Patents [OSTI]

    Feng, Zhili (Knoxville, TN) [Knoxville, TN; David, Stan A. (Knoxville, TN) [Knoxville, TN; Frederick, David Alan (Harriman, TN) [Harriman, TN

    2010-07-27T23:59:59.000Z

    Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

  7. Heat transfer and friction characteristics of air flow in microtubes Chien-Yuh Yang a,

    E-Print Network [OSTI]

    Kandlikar, Satish

    Heat transfer and friction characteristics of air flow in microtubes Chien-Yuh Yang a, , Chia September 2011 Keywords: Microtube Heat transfer Liquid Crystal Thermography a b s t r a c t Several researches dealing with the single-phase forced convection heat transfer inside microchannels have been

  8. Quantum mechanical aspects of friction and electric resistance in microscopic problems with applications to radiation physics

    E-Print Network [OSTI]

    Ulmer, W

    2015-01-01T23:59:59.000Z

    Friction incorporates the close connection between classical mechanics in irreversible thermodynamics. The translation to a quantum mechanical foundation is not trivial and requires a generalization of the Lagrange function. A change to electromagnetic circuits appears to more adequate, since the electric analogue (Ohms law) is related to scatter of electrons at lattice vibrations.

  9. FRICTION FACTOR IN HIGH PRESSURE NATURAL GAS PIPELINES FROM ROUGHNESS MEASUREMENTS

    E-Print Network [OSTI]

    Gudmundsson, Jon Steinar

    FRICTION FACTOR IN HIGH PRESSURE NATURAL GAS PIPELINES FROM ROUGHNESS MEASUREMENTS DETERMINATION DU and Technology, Norway ABSTRACT Pressure drop experiments on natural gas flow at 80 to 120 bar pressure and high of natural gas at typical operating pressures (100-180 bar). At such Reynolds numbers the classical Colebrook

  10. Friction factor for turbulent flow in rough pipes from Heisenberg's closure hypothesis

    E-Print Network [OSTI]

    Esteban Calzetta

    2009-01-02T23:59:59.000Z

    We show that the main results of the analysis of the friction factor for turbulent pipe flow reported in G. Gioia and P. Chakraborty (GC), Phys. Rev. Lett. 96, 044502 (1996) can be recovered by assuming the Heisenberg closure hypothesis for the turbulent spectrum. This highlights the structural features of the turbulent spectrum underlying GC's analysis.

  11. Ab-initio friction forces on the nanoscale: A DFT study of fcc Cu(111)

    E-Print Network [OSTI]

    Michael Wolloch; Gregor Feldbauer; Peter Mohn; Josef Redinger; András Vernes

    2014-08-26T23:59:59.000Z

    While there are a number of models that tackle the problem of calculating friction forces on the atomic level, providing a completely parameter-free approach remains a challenge. Here we present a quasi-static model to obtain an approximation to the nanofrictional response of dry, wearless systems based on quantum mechanical all-electron calculations. We propose a mechanism to allow dissipative sliding, which relies on atomic relaxations. We define two different ways of calculating the mean nanofriction force, both leading to an exponential friction-versus-load behavior for all sliding directions. Since our approach does not impose any limits on lengths and directions of the sliding paths, we investigate arbitrary sliding directions for an fcc Cu(111) interface and detect two periodic paths which form the upper and lower bound of nanofriction. For long aperiodic paths the friction force convergences to a value in between these limits. For low loads we retrieve the Derjaguin generalization of Amontons-Coulomb kinetic friction law which appears to be valid all the way down to the nanoscale. We observe a non-vanishing Derjaguin-offset even for atomically flat surfaces in dry contact.

  12. Variation, jumps, market frictions and high frequency data in financial econometrics

    E-Print Network [OSTI]

    Wolfe, Patrick J.

    Variation, jumps, market frictions and high frequency data in financial econometrics Ole E the econometrics of non-parametric estimation of the components of the variation of asset prices. This very active and order books. In our view the interaction of the new data sources with new econometric methodology

  13. Dynamics of static friction between steel and silicon Zhiping Yang, H. P. Zhang, and M. Marder

    E-Print Network [OSTI]

    Texas at Austin. University of

    Dynamics of static friction between steel and silicon Zhiping Yang, H. P. Zhang, and M. Marder 4, 2008) We conducted experiments in which steel and silicon or quartz are clamped together. Even experiments where silicon and quartz are clamped on steel, motion is measured down to the nanometer scale

  14. Linear elastic fracture mechanics predicts the propagation distance of frictional slip

    E-Print Network [OSTI]

    David S. Kammer; Mathilde Radiguet; Jean-Paul Ampuero; Jean-François Molinari

    2014-08-18T23:59:59.000Z

    When a frictional interface is subject to a localized shear load, it is often (experimentally) observed that local slip events initiate at the stress concentration and propagate over parts of the interface by arresting naturally before reaching the edge. We develop a theoretical model based on linear elastic fracture mechanics to describe the propagation of such precursory slip. The model's prediction of precursor lengths as a function of external load is in good quantitative agreement with laboratory experiments as well as with dynamic simulations, and provides thereby evidence to recognize frictional slip as a fracture phenomenon. We show that predicted precursor lengths depend, within given uncertainty ranges, mainly on the kinetic friction coefficient, and only weakly on other interface and material parameters. By simplifying the fracture mechanics model we also reveal sources for the observed non-linearity in the growth of precursor lengths as a function of the applied force. The discrete nature of precursors as well as the shear tractions caused by frustrated Poisson's expansion are found to be the dominant factors. Finally, we apply our model to a different, symmetric set-up and provide a prediction of the propagation distance of frictional slip for future experiments.

  15. Impact of Friction and Scale-Dependent Initial Stress on Radiated Energy-Moment Scaling

    E-Print Network [OSTI]

    Shaw, Bruce E.

    . Shaw Lamont­Doherty Earth Observatory, Columbia University, New York, USA The radiated energy coming271 Impact of Friction and Scale-Dependent Initial Stress on Radiated Energy-Moment Scaling Bruce E of elucidat- ing their radiated energy-moment scaling. We find, contrary to expectations, that apparent stress

  16. Correlations to predict frictional pressure loss of hydraulic-fracturing slurry in coiled tubing

    SciTech Connect (OSTI)

    Shah, S.; Zhoi, Y.X.; Bailey, M.; Hernandez, J. [University of Oklahoma, Norman, OK (United States)

    2009-08-15T23:59:59.000Z

    Compared with conventional-tubing fracturing, coiled-tubing (CT) fracturing has several advantages. CT fracturing has become an effective stimulation technique for multizone oil and gas wells. It is also an attractive production-enhancement method for multiseam coalbed-methane wells, and wells with bypassed zones. The excessive frictional pressure loss through CT has been a concern in fracturing. The small diameter of the string limits the cross-sectional area open to flow. Furthermore, the tubing curvature causes secondary flow and results in extra flow resistance. This increased frictional pressure loss results in high surface pumping pressure. The maximum possible pump rate and sand concentration, therefore, have to be reduced. To design a CT fracturing job properly, it is essential to predict the frictional pressure loss through the tubing accurately. This paper presents correlations for the prediction of frictional pressure loss of fracturing slurries in straight tubing and CT. They are developed on the basis of full-scale slurry-flow tests with 11/2-in. CT and slurries prepared with 35 lbm/1,000 gal of guar gel. The extensive experiments were conducted at the full-scale CT-flow test facility. The proposed correlations have been verified with the experimental data and actual field CT-fracturing data. Case studies of wells recently fractured are provided to demonstrate the application of the correlations. The correlations will be useful to the CT engineers in their hydraulics design calculations.

  17. Multilayer friction and attachment effects on energy dissipation in graphene nanoresonators

    E-Print Network [OSTI]

    Lin, Xi

    Multilayer friction and attachment effects on energy dissipation in graphene nanoresonators Sung graphene monolayers, as well as extrinsic attachment or clamping strength between graphene and a model silicon substrate on the energy dissipation Q-factors of oscillating graphene nanoresonators. Both

  18. Molecular simulation study of nanoscale friction for alkyl monolayers on Si,,111...

    E-Print Network [OSTI]

    Zhang, Luzheng

    . To calculate friction in MD simulations, two Si 111 surfaces coated with the alkyl monolayers were slid against is critical to the design of coatings for microelectromechanical systems. © 2002 American Institute of Physics, such as membranes, gears, motors, pumps and valves.1­3 The integration of miniaturized mechanical components

  19. Analysis of Instabilities and Their Impact on Friction Factor in Hole-Pattern Seals

    E-Print Network [OSTI]

    Sekaran, Aarthi 1985-

    2012-11-21T23:59:59.000Z

    The determination of the leakage and consequently the friction factor is an important part of analyzing the flow through a seal. This is done experimentally by means of a flat plate tester, which allows for the simplified representation of the seal...

  20. Assessing the frictional and baroclinic contributions to stratified wake formation: a parameter space study

    E-Print Network [OSTI]

    Smith, Jamie Brooke

    2006-08-16T23:59:59.000Z

    The baroclinic and surface-frictional contributions to stratified wake formation are considered as a function of the non-dimensional height ( = Nho/U) and aspect-ratio ( = ho/L) of the barrier. Numerical simulations are computed for a wide range...

  1. Low fault friction in Iran implies localized deformation for the ArabiaEurasia collision zone

    E-Print Network [OSTI]

    Vernant, Philippe

    Low fault friction in Iran implies localized deformation for the Arabia­Eurasia collision zone P velocity field of the present-day deformation in Iran is modeled using a 3-dimensional (3D) finite element of the kinematics in Iran, but the complex velocity field of the surrounding South Caspian basin cannot be fitted

  2. Molecular simulation study of nanoscale friction between alkyl monolayers on Si,,111... immersed in solvents

    E-Print Network [OSTI]

    Zhang, Luzheng

    of friction at different interfaces in various solvents is very important to micro- or nanoelectro- mechanical.1063/1.1578055 I. INTRODUCTION Micro- or nanoelectromechanical systems MEMS/ NEMS are the integration/hydrophobic hydrophilic/hydrophilic hydro- philic/hydrophobic interfaces in water.8,13 Thus, it is ex- pected

  3. Studies of the frictional heating of polycrystalline diamond compact drag tools during rock cutting

    SciTech Connect (OSTI)

    Ortega, A.; Glowka, D.A.

    1982-06-01T23:59:59.000Z

    A numerical-analytical model is developed to analyze temperatures in polycrystalline diamond compact (PDC) drag tools subject to localized frictional heating at a worn flat area and convective cooling at exposed lateral surfaces. Experimental measurements of convective heat transfer coefficients of PDC cutters in a uniform crossflow are presented and used in the model to predict temperatures under typical drilling conditions with fluid flow. The analysis compares favorably with measurements of frictional temperatures in controlled cutting tests on Tennessee marble. It is found that average temperatures at the wearflat contact zone vary directly with frictional force per unit area and are proportional to the one-half power of the cutting speed at the velocities investigated. Temperatures are found to be much more sensitive to decreases in the dynamic friction by lubrication than to increases in convective cooling rates beyond currently achievable levels with water or drilling fluids. It is shown that use of weighted drilling fluids may actually decrease cooling rates compared to those achieved with pure water. It is doubtful that tool temperatures can be kept below critical levels (750/sup 0/C) if air is employed as the drilling fluid. The degree of tool wear is found to have a major influence on the thermal response of the friction contact zone, so that for equal heating per contact area, a worn tool will run much hotter than a sharp tool. It is concluded that tool temperatures may be kept below critical levels with conventional water or mud cooling as long as the fluid provides good cutter-rock lubrication.

  4. Is the friction angle the maximum slope of a free surface of a non cohesive material?

    E-Print Network [OSTI]

    A. Modaressi; P. Evesque

    2005-07-13T23:59:59.000Z

    Starting from a symmetric triangular pile with a horizontal basis and rotating the basis in the vertical plane, we have determined the evolution of the stress distribution as a function of the basis inclination using Finite Elements method with an elastic-perfectly plastic constitutive model, defined by its friction angle, without cohesion. It is found that when the yield function is the Drucker-Prager one, stress distribution satisfying equilibrium can be found even when one of the free-surface slopes is larger than the friction angle. This means that piles with a slope larger than the friction angle can be (at least) marginally stable and that slope rotation is not always a destabilising perturbation direction. On the contrary, it is found that the slope cannot overpass the friction angle when a Mohr-Coulomb yield function is used. Theoretical explanation of these facts is given which enlightens the role plaid by the intermediate principal stress in both cases of the Mohr-Coulomb criterion and of the Drucker-Prager one. It is then argued that the Mohr-Coulomb criterion assumes a spontaneous symmetry breaking, as soon as the two smallest principal stresses are different ; this is not physical most likely; so this criterion shall be replaced by a Drucker-Prager criterion in the vicinity of the equality, which leads to the previous anomalous behaviour ; so these numerical computations enlighten the avalanche process: they show that no dynamical angle larger than the static one is needed to understand avalanching. It is in agreement with previous experimental results. Furthermore, these results show that the maximum angle of repose can be modified using cyclic rotations; we propose a procedure that allows to achieve a maximum angle of repose to be equal to the friction angle .

  5. Investigating students' mental models and knowledge construction of microscopic friction. II. Implications for curriculum design and development

    E-Print Network [OSTI]

    Zollman, Dean

    ; and in explain- ing the lubricating mechanism of oil. When students were asked to sketch how the smoothest

  6. Kinetics of Reductive Dissolution of Hematite by Bioreduced Anthraquinone-2,6-disulfate

    SciTech Connect (OSTI)

    Liu, Chongxuan; Zachara, John M.; Foster, Nancy S.; Strickland, Janae

    2007-11-15T23:59:59.000Z

    The reductive dissolution of hematite (?-Fe2O3) was investigated in a flow-through system using AH2DS, a reduced form of anthraquinone- 2,6 disulfonate (AQDS), which is often used as an electron shuttling compound in studies of dissimilatory microbial reduction of iron oxides. Influent flow-rate, pH, Fe(II) and phosphate concentrations were varied to investigate the redox reaction kinetics. The effluent AH2DS, AQDS, and Fe(II) concentrations changed significantly within the first half hour of AH2DS reaction with hematite and then gradually evolved toward steady-state. The steady-state rates decreased with increasing pH from 4.5 to 7.6 and decreased with decreasing flow-rate. The rates also decreased with increasing influent concentration of Fe(II) or phosphate that formed surface complexes at the experimental pH. Mineral surface properties, Fe(II) complexation reactions, and AQDS sorption on hematite surfaces were independently investigated for interpreting hematite reductive dissolution kinetics. AH2DS sorption to hematite was inferred from the parallel measurements of AQDS and AH2DS sorption to ?-Al2O3, a redox stable analog of ?-Fe2O3. Decreasing Fe(II) and increasing AH2DS sorption by controlling flow residence time, influent pH, Fe(II) and phosphate concentrations increased the rates of reductive dissolution. The rates were also affected by the redox reaction free energy when reductive dissolution approached equilibrium, as shown by the effect of increasing the influent concentration of Fe(II).

  7. Nevada State Energy Reduction Plan

    Broader source: Energy.gov [DOE]

    As mandated by the Nevada statutes, the Nevada Energy Office prepared a state energy reduction plan which requires state agencies, departments, and other entities in the Executive Branch to reduce...

  8. Economics of Steam Pressure Reduction

    E-Print Network [OSTI]

    Sylva, D. M.

    Economics of Steam Pressure Reduction is a technical paper that addresses the operating and economic advantages associated with the program to lower the steam operating pressure. Evaluation of a testing program will be discussed. The paper...

  9. Plasma-assisted catalytic reduction system

    DOE Patents [OSTI]

    Vogtlin, G.E.; Merritt, B.T.; Hsiao, M.C.; Wallman, P.H.; Penetrante, B.M.

    1998-01-27T23:59:59.000Z

    Non-thermal plasma gas treatment is combined with selective catalytic reduction to enhance NO{sub x} reduction in oxygen-rich vehicle engine exhausts. 8 figs.

  10. Electrocatalytic Reactivity for Oxygen Reduction of Palladium...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Reactivity for Oxygen Reduction of Palladium-Modified Carbon Nanotubes Synthesized in Supercritical Fluid. Electrocatalytic Reactivity for Oxygen Reduction of Palladium-Modified...

  11. Facile and controllable electrochemical reduction of graphene...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and controllable electrochemical reduction of graphene oxide and its applications. Facile and controllable electrochemical reduction of graphene oxide and its applications....

  12. Characterizing Test Methods and Emissions Reduction Performance...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Test Methods and Emissions Reduction Performance of In-Use Diesel Retrofit Technologies from the National Clean Diesel Campaign Characterizing Test Methods and Emissions Reduction...

  13. Demonstrating Fuel Consumption and Emissions Reductions with...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Fuel Consumption and Emissions Reductions with Next Generation Model-Based Diesel Engine Control Demonstrating Fuel Consumption and Emissions Reductions with Next Generation...

  14. Friction of a slider on a granular layer: Non-monotonic thickness dependence and effect of boundary conditions

    E-Print Network [OSTI]

    Saloome Siavoshi; Ashish V. Orpe; Arshad Kudrolli

    2005-12-22T23:59:59.000Z

    We investigate the effective friction encountered by a mass sliding on a granular layer as a function of bed thickness and boundary roughness conditions. The observed friction has minima for a small number of layers before it increases and saturates to a value which depends on the roughness of the sliding surface. We use an index-matched interstitial liquid to probe the internal motion of the grains with fluorescence imaging in a regime where the liquid has no significant effect on the measured friction. The shear profiles obtained as a function of depth show decrease in slip near the sliding surface as the layer thickness is increased. We propose that the friction depends on the degree of grain confinement relative to the sliding surfaces.

  15. Brittle and Ductile Friction and the Physics of Tectonic Tremor 1. Geophysics Group, Los Alamos National Laboratory

    E-Print Network [OSTI]

    Daub,Eric G.

    for Nonlinear Studies, Los Alamos National Laboratory 3. United States Geological Survey, Menlo Park 4Brittle and Ductile Friction and the Physics of Tectonic Tremor 1. Geophysics Group, Los Alamos

  16. Friction Stir Welding Of Ma957 Oxide Dispersion Strengthened Ferritic Steel

    SciTech Connect (OSTI)

    Howard, Stanley M.; Jasthi, Bharat K.; Arbegast, William J.; Grant, Glenn J.; Koduri, Santhosh K.; Herling, Darrell R.; Gelles, David S.

    2005-04-02T23:59:59.000Z

    A 1-in. (25.4 mm) diameter yttria-dispersion-strengthened MA957 ferritic steel alloy tube with a 0.125" (3.18 mm) wall thickness was successfully plasticized by friction stir welding. The pin tool was a W-Re tool with 0.125" (3.17 mm) diameter tip. It showed no discernable wear for the total 12" (305 mm) of weld. Weld conditions were 1000 and 1400 RPM, 4 in/min (101 mm/min), with and without preheating to 135ºC. Metallographic analysis of the post friction-stir welded material showed a decrease in material hardness to 225±22 HV compared to the parent material at 373±21 HV. All weld conditions produced plasticization; however, improved plasticization was observed for preheated samples

  17. Neutron diffraction measurements of residual stresses in friction stir welding: a review

    SciTech Connect (OSTI)

    Woo, Wan Chuck [ORNL; Feng, Zhili [ORNL; Wang, Xun-Li [ORNL; David, Stan A [ORNL

    2011-01-01T23:59:59.000Z

    Significant amounts of residual stresses are often generated during welding and result in critical degradation of the structural integrity and performance of components. Neutron diffraction has become a well established technique for the determination of residual stresses in welds because of the unique deep penetration, three-dimensional mapping capability, and volume averaged bulk measurements characteristic of the scattering neutron beam. Friction stir welding has gained prominence in recent years. The authors reviewed a number of neutron diffraction measurements of residual stresses in friction stir welds and highlighted examples addressing how the microstructures and residual stresses are correlated with each other. An example of in situ neutron diffraction measurement result shows the evolution of the residual stresses during welding.

  18. Initial increase, ''peaking effect'', in the internal friction of copper following pulsed neutron and electron irradiation

    SciTech Connect (OSTI)

    Simpson, H.M.; Parkin, D.M.; Goldstone, J.A.; Hemsky, J.W.

    1985-01-01T23:59:59.000Z

    Under certain experimental conditions the internal friction in metals can first increase and following prolonged irradiation decrease. Many models have been proposed to account for this ''peaking effect''; however, in many of the cases, no effort is made to distinguish between the influence of interstitials and/or vacancies. To determine the nature of the point defect responsible for the peaking effect in high purity copper, we have performed a series of pulsed irradiations using neutrons and electrons. In all of the experiments an initial very rapid rise in the internal friction and Young's modulus was observed. These data show that a fast diffusing defect is responsible for the peaking effect: i.e. the interstitial.

  19. Nonlinear analysis of time series of vibration data from a friction brake: SSA, PCA, and MFDFA

    E-Print Network [OSTI]

    Nikolay K. Vitanov; Norbert P. Hoffmann; Boris Wernitz

    2014-10-23T23:59:59.000Z

    We use the methodology of singular spectrum analysis (SSA), principal component analysis (PCA), and multi-fractal detrended fluctuation analysis (MFDFA), for investigating characteristics of vibration time series data from a friction brake. SSA and PCA are used to study the long time-scale characteristics of the time series. MFDFA is applied for investigating all time scales up to the smallest recorded one. It turns out that the majority of the long time-scale dynamics, that is presumably dominated by the structural dynamics of the brake system, is dominated by very few active dimensions only and can well be understood in terms of low dimensional chaotic attractors. The multi-fractal analysis shows that the fast dynamical processes originating in the friction interface are in turn truly multi-scale in nature.

  20. The friction factor of two-dimensional rough-boundary turbulent soap film flows

    E-Print Network [OSTI]

    Nicholas Guttenberg; Nigel Goldenfeld

    2008-08-11T23:59:59.000Z

    We use momentum transfer arguments to predict the friction factor $f$ in two-dimensional turbulent soap-film flows with rough boundaries (an analogue of three-dimensional pipe flow) as a function of Reynolds number Re and roughness $r$, considering separately the inverse energy cascade and the forward enstrophy cascade. At intermediate Re, we predict a Blasius-like friction factor scaling of $f\\propto\\textrm{Re}^{-1/2}$ in flows dominated by the enstrophy cascade, distinct from the energy cascade scaling of $\\textrm{Re}^{-1/4}$. For large Re, $f \\sim r$ in the enstrophy-dominated case. We use conformal map techniques to perform direct numerical simulations that are in satisfactory agreement with theory, and exhibit data collapse scaling of roughness-induced criticality, previously shown to arise in the 3D pipe data of Nikuradse.

  1. Cherenkov friction on a neutral particle moving parallel to a dielectric

    E-Print Network [OSTI]

    Gregor Pieplow; Carsten Henkel

    2014-02-18T23:59:59.000Z

    Based on a fully relativistic framework and the assumption of local equilibrium, we describe a simple mechanism of quantum friction for a particle moving parallel to a dielectric. The Cherenkov effect explains how the bare ground state becomes globally unstable and how fluctuations of the electromagnetic field and the particle's dipole are converted into pairs of excitations. Modelling the particle as a silver nano-sphere, we investigate the spectrum of the force and its velocity dependence. We find that the damping of the plasmon resonance in the silver particle has a relatively strong impact near the Cherenkov threshold velocity. We also present an expansion of the friction force near the threshold velocity for both damped and undamped particles.

  2. Attractiveness of periodic orbits in parametrically forced systemswith time-increasing friction

    E-Print Network [OSTI]

    Michele Bartuccelli; Jonathan Deane; Guido Gentile

    2012-07-18T23:59:59.000Z

    We consider dissipative one-dimensional systems subject to a periodic force and study numerically how a time-varying friction affects the dynamics. As a model system, particularly suited for numerical analysis, we investigate the driven cubic oscillator in the presence of friction. We find that, if the damping coefficient increases in time up to a final constant value, then the basins of attraction of the leading resonances are larger than they would have been if the coefficient had been fixed at that value since the beginning. From a quantitative point of view, the scenario depends both on the final value and the growth rate of the damping coefficient. The relevance of the results for the spin-orbit model are discussed in some detail.

  3. Dynamical friction in constant density cores: a failure of the Chandrasekhar formula

    E-Print Network [OSTI]

    J. I. Read; Tobias Goerdt; Ben Moore; A. P. Pontzen; Joachim Stadel; George Lake

    2006-06-26T23:59:59.000Z

    Using analytic calculations and N-body simulations we show that in constant density (harmonic) cores, sinking satellites undergo an initial phase of very rapid (super-Chandrasekhar) dynamical friction, after which they experience no dynamical friction at all. For density profiles with a central power law profile of log-slope, $-\\alpha$, the infalling satellite heats the background and causes $\\alpha$ to decrease. For $\\alpha < 0.5$ initially, the satellite generates a small central constant density core and stalls as in the $\\alpha = 0$ case. We discuss some astrophysical applications of our results to decaying satellite orbits, galactic bars and mergers of supermassive black hole binaries. In a companion paper we show that a central constant density core can provide a natural solution to the timing problem for Fornax's globular clusters.

  4. ACRA-II

    Energy Science and Technology Software Center (OSTI)

    003089IBMPC00 ACRA-II: Kernel Integration Code System for Estimation of Radiation Doses Caused by a Hypothetical Reactor Accident   

  5. Heat transfer and friction in a square channel with one-wall or two-wall rib turbulators

    E-Print Network [OSTI]

    Huang, Jie Joy

    1991-01-01T23:59:59.000Z

    walls 83 66 Ribbed side Nusselt number ratio versus friction factor ratio for broken ribs on one wall 84 67 Smooth side Nusselt number ratio versus friction factor ratio for broken ribs on one wall . , 68 Ribbed side Nusselt number ratio versus... on one wall . 95 96 97 INTRODUCTION Early heat transfer study shows that roughening the surface is an effective way to enhance the heat transfer from a surface. Modern turbine design applies turbulence promoters/ribs inside cooling passages...

  6. An experimental and analytical study of annular two phase flow friction pressure drop in a reduced acceleration field

    E-Print Network [OSTI]

    Wheeler, Montgomery

    1992-01-01T23:59:59.000Z

    for the same mass fluxes and mass qualities. The reduced acceleration pressure drops were found to be 45% greater overall than the 1-g pressure drops. In addition, the reduced acceleration flows were modeled using a universal velocity profile integral... approach to determine the liquid film thickness and the interfacial friction factor. The reduced acceleration annular flow interfacial friction factors were compared with current models for vertical up-flow in a 1-g environment. The reduced acceleration...

  7. Eutectic structures in friction spot welding joint of aluminum alloy to copper

    SciTech Connect (OSTI)

    Shen, Junjun, E-mail: junjun.shen@hzg.de; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Solid-State Joining Processes, Max-Planck-Str. 1, 21502 Geesthacht (Germany)

    2014-05-12T23:59:59.000Z

    A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

  8. A robotic crawler exploiting directional frictional interactions: experiments, numerics, and derivation of a reduced model

    E-Print Network [OSTI]

    Giovanni Noselli; Antonio DeSimone

    2014-08-26T23:59:59.000Z

    We present experimental and numerical results for a model crawler which is able to extract net positional changes from reciprocal shape changes, i.e. 'breathing-like' deformations, thanks to directional, frictional interactions with a textured solid substrate, mediated by flexible inclined feet. We also present a simple reduced model that captures the essential features of the kinematics and energetics of the gait, and compare its predictions with the results from experiments and from numerical simulations.

  9. Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

    SciTech Connect (OSTI)

    Sathiskumar, R., E-mail: sathiscit2011@gmail.com [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Murugan, N., E-mail: murugan@cit.edu.in [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Dinaharan, I., E-mail: dinaweld2009@gmail.com [Department of Mechanical Engineering, V V College of Engineering, Tisaiyanvilai, 627 657 Tamil Nadu (India); Vijay, S.J., E-mail: vijayjoseph@karunya.edu [Centre for Research in Metallurgy (CRM), School of Mechanical Sciences, Karunya University, Coimbatore, 641 114 Tamil Nadu (India)

    2013-10-15T23:59:59.000Z

    Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B{sub 4}C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B{sub 4}C particles. The dimensions of the groove was varied to result in five different volume fractions of B{sub 4}C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B{sub 4}C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B{sub 4}C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B{sub 4}C surface composites. When the volume fraction of B{sub 4}C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. Highlights: • Fabrication of Cu/B{sub 4}C surface composite by friction stir processing • Analyzing the effect of B{sub 4}C particles on the properties of Cu/B4C surface composite • Increased volume fraction of B{sub 4}C particles reduced the area of surface composite. • Increased volume fraction of B{sub 4}C particles enhanced the microhardness and wear rate. • B{sub 4}C particles altered the wear mode from microcutting to abrasive.

  10. Microbial reduction of iron ore

    DOE Patents [OSTI]

    Hoffmann, Michael R. (Pasadena, CA); Arnold, Robert G. (Pasadena, CA); Stephanopoulos, Gregory (Pasadena, CA)

    1989-01-01T23:59:59.000Z

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry.

  11. Microbial reduction of iron ore

    DOE Patents [OSTI]

    Hoffmann, M.R.; Arnold, R.G.; Stephanopoulos, G.

    1989-11-14T23:59:59.000Z

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry. 11 figs.

  12. Forest Fuels ReductionForest Fuels Reduction Department of

    E-Print Network [OSTI]

    Bolding, M. Chad

    are the soil management and watershed implications from alternative fuels reduction approaches? 3. How do and implement appropriate technologies to meet sustainable forest management objectives involving fuels Management 1. What should the size and distribution of the residual woody material be on-site from a fire

  13. CSC6870 Computer Graphics II CSC6870 Computer Graphics II

    E-Print Network [OSTI]

    Hua, Jing

    CSC6870 Computer Graphics II Surfaces CSC6870 Computer Graphics II Surfaces · Plane · Quadratic. CSC6870 Computer Graphics II Plane and Intersection CSC6870 Computer Graphics II Plane Equations · General plane equation ax+by+cz+d=0 · Normal of the plane n=[a, b, c] CSC6870 Computer Graphics II

  14. DYNAMICAL FRICTION IN A GASEOUS MEDIUM WITH A LARGE-SCALE MAGNETIC FIELD

    SciTech Connect (OSTI)

    Sanchez-Salcedo, F. J., E-mail: jsanchez@astroscu.unam.mx [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico City (Mexico)

    2012-02-01T23:59:59.000Z

    The dynamical friction force experienced by a massive gravitating body moving through a gaseous medium is modified by sufficiently strong large-scale magnetic fields. Using linear perturbation theory, we calculate the structure of the wake generated by, and the gravitational drag force on, a body traveling in a straight-line trajectory in a uniformly magnetized medium. The functional form of the drag force as a function of the Mach number ({identical_to} V{sub 0}/c{sub s} , where V{sub 0} is the velocity of the body and c{sub s} is the sound speed) depends on the strength of the magnetic field and on the angle between the velocity of the perturber and the direction of the magnetic field. In particular, the peak value of the drag force is not near Mach number {approx}1 for a perturber moving in a sufficiently magnetized medium. As a rule of thumb, we may state that for supersonic motion, magnetic fields act to suppress dynamical friction; for subsonic motion, they tend to enhance dynamical friction. For perturbers moving along the magnetic field lines, the drag force at some subsonic Mach numbers may be stronger than at supersonic velocities. We also mention the relevance of our findings to black hole coalescence in galactic nuclei.

  15. Explicit Solvent Simulations of Friction between Brush Layers of Charged and Neutral Bottle-Brush Macromolecules

    SciTech Connect (OSTI)

    Carrillo, Jan-Michael [University of Connecticut] [University of Connecticut; Brown, W Michael [ORNL] [ORNL; Dobrynin, Andrey [University of Connecticut] [University of Connecticut

    2012-01-01T23:59:59.000Z

    We study friction between charged and neutral brush layers of bottle-brush macromolecules using molecular dynamics simulations. In our simulations the solvent molecules were treated explicitly. The deformation of the bottle-brush macromolecules under the shear were studied as a function of the substrate separation and shear stress. For charged bottle-brush layers we study effect of the added salt on the brush lubricating properties to elucidate factors responsible for energy dissipation in charged and neutral brush systems. Our simulations have shown that for both charged and neutral brush systems the main deformation mode of the bottle-brush macromolecule is associated with the backbone deformation. This deformation mode manifests itself in the backbone deformation ratio, , and shear viscosity, , to be universal functions of the Weissenberg number W. The value of the friction coefficient, , and viscosity, , are larger for the charged bottle-brush coatings in comparison with those for neutral brushes at the same separation distance, D, between substrates. The additional energy dissipation generated by brush sliding in charged bottle-brush systems is due to electrostatic coupling between bottle-brush and counterion motion. This coupling weakens as salt concentration, cs, increases resulting in values of the viscosity, , and friction coefficient, , approaching corresponding values obtained for neutral brush systems.

  16. A functional approach to quantum friction: effective action and dissipative force

    E-Print Network [OSTI]

    M. Belén Farías; César D. Fosco; Fernando C. Lombardo; Francisco D. Mazzitelli; Adrián E. Rubio López

    2014-12-30T23:59:59.000Z

    We study the Casimir friction due to the relative, uniform, lateral motion of two parallel semitransparent mirrors coupled to a vacuum real scalar field, $\\phi$. We follow a functional approach, whereby nonlocal terms in the action for $\\phi$, concentrated on the mirrors' locii, appear after functional integration of the microscopic degrees of freedom. This action for $\\phi$, which incorporates the relevant properties of the mirrors, is then used as the starting point for two complementary evaluations: Firstly, we calculate the { in-out} effective action for the system, which develops an imaginary part, hence a non-vanishing probability for the decay (because of friction) of the initial vacuum state. Secondly, we evaluate another observable: the vacuum expectation value of the frictional force, using the { in-in} or Closed Time Path formalism. Explicit results are presented for zero-width mirrors and half-spaces, in a model where the microscopic degrees of freedom at the mirrors are a set of identical quantum harmonic oscillators, linearly coupled to $\\phi$

  17. The Effect of surface morphology on the friction of Electrogalvanized sheet steel in forming processes

    SciTech Connect (OSTI)

    Skarpelos, P.N. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1993-12-01T23:59:59.000Z

    The effect in the drawbead simulator test were evaluated for a set of commercially coated steels and a set of laboratory coated steels with underlying surfaces produced by laser textured, shot blast, and electro-discharge textured rolls. In general, surfaces with higher roughness (R{sub a} parameter) measured lower friction in the DBS tests. The requisite roughness amplitude necessary for low friction was moderated somewhat by having a more closely spaced roughness as described by the median wavelength, {lambda}m, of the power spectrum. This effect is due to interaction with the lubricant by the micro-roughness imparted by the galvanizing process. The lubricant tends to be retained better by the surfaces with the micro-roughness, thereby increasing the amount of elasto- and plasto-hydrodynamic support of the load. Other variables, such as large variations in thickness of the sheet can mask the effect of the surface by changing the actual distance of sliding contact during the DBS test. For tests where the amount of sliding is similar, the effect of roughness is significant. The friction measured for EG steels in the DBS test is dominated by deformation of the surface with plowing by the asperities of the tooling adding to that caused by the deformation. The size of the plow marks in the deformed surfaces corresponds to the roughness of the tooling and no significant evidence of wear particles was observed.

  18. An Approach for Reduction of the Security Overhead in Smart Grid Communication Infrastructure Employing Dedicated Encryption

    E-Print Network [OSTI]

    Kavcic, Aleksandar

    network, and Internet. The sensor nodes, such as Phasor Measuring Units (PMUs) and Smart Meters (SMs expensive to equip each tiny IT device with AC to DC convertor; (ii) the smart- meters are twoAn Approach for Reduction of the Security Overhead in Smart Grid Communication Infrastructure

  19. Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

    SciTech Connect (OSTI)

    D'Urso, G.; Longo, M.; Giardini, C. [University of Bergamo-Dept. of Design and Technologies-Italy-Viale Marconi 5, 24044 Dalmine (Italy)

    2011-05-04T23:59:59.000Z

    Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225x60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the wall thickness were measured for each tested tube.

  20. Lead reduction in ambient air

    SciTech Connect (OSTI)

    Smith, R.D.; Kiehn, O.A.; Wilburn, D.R.; Bowyer, R.C.

    1987-01-01T23:59:59.000Z

    The Bureau of Mines evaluated the emission control methods, including the capital investments and operating cost, necessary for further reducing lead levels in ambient air at the Glover, Herculaneum, and Buick smelter-refineries in Missouri and the East Helena, MT, smelter. This report presents theoretically achievable lead emission reductions and estimated capital and operating costs.

  1. Beta Reduction Constraints Manuel Bodirsky Katrin Erk

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Beta Reduction Constraints Manuel Bodirsky Katrin Erk Alexander Koller Joachim Niehren Programming partially. In this paper, we introduce beta reduction constraints to describe beta reduction steps between partially known lambda terms. We show that beta reduction constraints can be expressed in an extension

  2. Adaptive Port Reduction in Static Condensation

    E-Print Network [OSTI]

    Rønquist, Einar M.

    Adaptive Port Reduction in Static Condensation JL Eftang DBP Huynh DJ Knezevic EM Rønquist a framework for adaptive reduction of the degrees of freedom associated with ports in static condensation (SC reduction for the interior of a component with model order reduction on the ports in order to rapidly

  3. Reduction And Immobilization Of Hexavalent Chromium By Microbially Reduced Fe-bearing Clay Minerals

    SciTech Connect (OSTI)

    Bishop, Michael E.; Glasser, Paul; Dong, Hailiang; Arey, Bruce W.; Kovarik, Libor

    2014-05-15T23:59:59.000Z

    Hexavalent chromium (Cr6+) is a major contaminant in the environment. As a redox-sensitive element, the fate and toxicity of chromium is controlled by reduction-oxidation (redox) reactions. Previous research has shown the ability of structural Fe(II) in naturally present and chemically reduced clay minerals to reduce Cr6+ to Cr(III) as a way of immobilization and detoxification. However, it is still poorly known whether or not structural Fe(II) in biologically reduced clay minerals exhibits a similar reactivity and if so, what the kinetics and mechanisms of Cr6+ reduction are. The objective of this study was to determine the kinetics and possible mechanisms of Cr6+ reduction by structural Fe(II) in microbially reduced clay minerals and the nature of reduced Cr(III). Structural Fe(III) in nontronite (NAu-2), montmorillonite (SWy-2), chlorite (CCa-2), and clay-rich sediments from the Ringold Formation of the Hanford site of Washington State, USA was first bioreduced to Fe(II) by an iron-reducing bacterium Geobacter sulfurreducens with acetate as the sole electron donor and anthraquinone-2,6-disulfate (AQDS) as electron shuttle in synthetic groundwater (pH 7). Biogenic Fe(II) was then used to reduce aqueous Cr6+ at three different temperatures, 10°, 20°, and 30°C, in order to determine the temperature dependence of the redox reaction between Cr6+ and clay-Fe(II). The results showed that nontronite and montmorillonite were most effective in reducing aqueous Cr6+ at all three temperatures. In contrast, most Fe(II) in chlorite was not reactive towards Cr6+ reduction at 10°C, though at 30°C there was some reduction. For all the clay minerals, the ratio of total Fe(II) oxidized to Cr6+ reduced was close to the expected stoichiometric value of 3. Characterization of the Cr-clay reaction product with scanning electron microscopy with focused ion beam and transmission electron microscopy with electron energy loss spectroscopy revealed that reduced chromium was possibly in the form of sub-nanometer Cr2O3 in association with residual clay minerals as micro-aggregates. This textural association was expected to minimize the chance of Cr(III) reoxidation upon exposure to oxidants. These results are important for our understanding of how various clay minerals may be used to reductively immobilize the heavy metal contaminant Cr in the environment.

  4. Elastic Properties and Internal Friction of Two Magnesium Alloys at Elevated Temperatures

    SciTech Connect (OSTI)

    Freels, M.; Liaw, P. K.; Garlea, E.; Morrell, J. S.; Radiovic, M.

    2011-06-01T23:59:59.000Z

    The elastic properties and internal friction of two magnesium alloys were studied from 25 C to 450 C using Resonant Ultrasound Spectroscopy (RUS). The Young's moduli decrease with increasing temperature. At 200 C, a change in the temperature dependence of the elastic constants is observed. The internal friction increases significantly with increasing temperature above 200 C. The observed changes in the temperature dependence of the elastic constants and the internal friction are the result of anelastic relaxation by grain boundary sliding at elevated temperatures. Elastic properties govern the behavior of a materials subjected to stress over a region of strain where the material behaves elastically. The elastic properties, including the Young's modulus (E), shear modulus (G), bulk modulus (B), and Poisson's ratio (?), are of significant interest to many design and engineering applications. The choice of the most appropriate material for a particular application at elevated temperatures therefore requires knowledge of its elastic properties as a function of temperature. In addition, mechanical vibration can cause significant damage in the automotive, aerospace, and architectural industries and thus, the ability of a material to dissipate elastic strain energy in materials, known as damping or internal friction, is also important property. Internal friction can be the result of a wide range of physical mechanisms, and depends on the material, temperature, and frequency of the loading. When utilized effectively in engineering applications, the damping capacity of a material can remove undesirable noise and vibration as heat to the surroundings. The elastic properties of materials can be determined by static or dynamic methods. Resonant Ultrasound Spectroscopy (RUS), used in this study, is a unique and sophisticated non-destructive dynamic technique for determining the complete elastic tensor of a solid by measuring the resonant spectrum of mechanical resonance for a sample of known geometry, dimensions, and mass. In addition, RUS allows determination of internal friction, or damping, at different frequencies and temperatures. Polycrystalline pure magnesium (Mg) exhibits excellent high damping properties. However, the poor mechanical properties limit the applications of pure Mg. Although alloying can improve the mechanical properties of Mg, the damping properties are reduced with additions of alloying elements. Therefore, it becomes necessary to study and develop Mg-alloys with simultaneous high damping capacity and improved mechanical properties. Moreover, studies involving the high temperature dynamic elastic properties of Mg alloys are limited. In this study, the elastic properties and internal friction of two magnesium alloys were studied at elevated temperatures using RUS. The effect of alloy composition and grain size was investigated. The wrought magnesium alloys AZ31 and ZK60 were employed. Table 1 gives the nominal chemical compositions of these two alloys. The ZK60 alloy is a commercial extruded plate with a T5 temper, i.e. solution-treated at 535 C for two hours, quenched in hot water, and aged at 185 C for 24 hours. The AZ31 alloy is a commercial rolled plate with a H24 temper, i.e. strain hardened and partially annealed.

  5. Dynamic reduction, Version 1. 0

    SciTech Connect (OSTI)

    Rogers, G.J.; Wong, D.Y.; Ottevangers, J.; Wang, L. (Ontario Hydro, Toronto, ON (Canada))

    1993-04-01T23:59:59.000Z

    This report describes the theoretical background of the EPRI Dynamic Reduction DYNRED V 1.0. EPRI initiated research under project RP763 to develop the original reduction program DYNEQU. This program was the first to be based on the concept of aggregating of coherent groups of synchronous generators into a single equivalent generator model. While technically advanced, DYNEQU proved difficult to use. Since then, the stability problems encountered in power system planning and operations have changed. The emphasis on first swing transient stability has been replaced by emphasis on inter-area oscillations and voltage stability. The method of identification of coherent generators used in DYNEQU is based on the comparison of rotor angle swings, in a linearized system model, following a fault. It has been shown that this method of coherency identification is good for first swing stability. For inter-area oscillation studies, this method of generator aggregation is less accurate. Far better, are identification methods based on the structure of the power system. Because of these changes in the requirements for reduced order power system models, a new dynamic reduction program (DYNRED) has been developed under EPRI project RP2447-1. It is coherency based, as is DYNEQU, but it has structurally based coherency identification methods in addition to the method used in DYNEQU. This report describes the techniques used in DYNRED, that is: Coherency Identification; Network Reduction; Method of Aggregation, Generator Aggregation, Excitation Aggregation, Primemover/Governor Aggregation. An example of the application of DYNRED to the reduction of a large interconnected power system model is also presented. DYNRED uses the special modeling and network solution techniques developed to enable systems having up to 12,000 bus to be studied. Dynamic data is completely compatible between MASS, PEALS, and the EPRI Extended Transient Midterm Stability Program (ETMSP).

  6. Abstract Presented at Synchrotron Environmental Science II (SES-II)

    E-Print Network [OSTI]

    Brookhaven National Laboratory

    Abstract Presented at Synchrotron Environmental Science II (SES-II) Argonne National Laboratory - 6 such as dioxins and furans, polychlorinated biphenyls (PCBs), and polynuclear aromatic hydrocarbons (PAHs). *Work

  7. Effect of Magnetic Field on The Friction and Wear Displayed by The Scratch of Oil Lubricated Steel

    E-Print Network [OSTI]

    unknown authors

    Abstract — The present work discusses the effect of magnetic field on the friction and wear of steel scratched by TiC insert. The steel was lubricated by oil and dispersed by iron, copper and aluminium powders as well as polymeric powders such as high density polyethylene (PE), polymethyl methacrylate (PMMA) and polyamide (PA6). Molybdenum disulphide (MoS 2) and graphite (C) were added to the oil as dispersant. Paraffin oil was used as lubricant. Friction coefficient and wear of the tested composites were investigated using a tribometer designed and manufactured for that purpose. It was found that application of induction magnetic field decreased friction coefficient. The decrease was significant for oil lubricated steel and oil dispersed by aluminium, copper, PMMA and PA6 + 10 wt. % C, while addition of iron, PE and MoS 2 particles showed slight friction decrease. At no magnetic field friction coefficient for oil dispersed by aluminium and copper particles showed values lower than that observed for oil dispersed by iron particles. The lowest values of friction coefficient were displayed by oil dispersed by PE particles. Magnetic field caused significant wear increase for oil lubricated steel, where aluminium, copper and PA6 + C particles displayed relatively higher wear, while addition of iron, PE, PMMA and MoS 2 particles showed slight wear increase. At no magnetic field wear decreased due to the action of aluminium particles which formed a continuous layer on the steel surface and consequently decreased wear. Wear of oil lubricated steel dispersed by PE particles displayed relatively low values. Magnetic field showed no significant change on wear of the steel surface. Index Term-- Induction, magnetic field, scratch, friction coefficient, wear, iron, copper, aluminium polymethyl methacrylate, polyethylene, polyamide, molybdenum disulphide, paraffin oil. I.

  8. Stable reduction product of misonidazole

    SciTech Connect (OSTI)

    Panicucci, R.; McClelland, R.A.; Rauth, A.M.

    1986-07-01T23:59:59.000Z

    The predominant stable product (greater than 80%) of the anaerobic radiation chemical reduction (pH 7, formate, N/sub 2/O) of misonidazole (MISO) has been identified as the cyclic guanidinium ion MISO-DDI, a 4,5-dihydro-4,5-dihydroxyimidazolium ion. This cation was prepared as its sulfate salt by the reaction of glyoxal and the appropriate N-substituted guanidinium sulfate. Its formation during MISO reduction was established by NMR spectral comparison and by derivatization as glyoxal bis-oxime, which was formed in 86% yield in fully reduced systems. The toxicity of pure MISO-DDI X sulfate was examined in vivo (C/sub 3/H mice) and in vitro (CHO cells). This product is less toxic than the parent MISO and free glyoxal. A reactive, short-lived, intermediate is suggested as the agent responsible for the toxicity of MISO under hypoxic conditions.

  9. Wind load reduction for heliostats

    SciTech Connect (OSTI)

    Peterka, J.A.; Hosoya, N.; Bienkiewicz, B.; Cermak, J.E.

    1986-05-01T23:59:59.000Z

    This report presents the results of wind-tunnel tests supported through the Solar Energy Research Institute (SERI) by the Office of Solar Thermal Technology of the US Department of Energy as part of the SERI research effort on innovative concentrators. As gravity loads on drive mechanisms are reduced through stretched-membrane technology, the wind-load contribution of the required drive capacity increases in percentage. Reduction of wind loads can provide economy in support structure and heliostat drive. Wind-tunnel tests have been directed at finding methods to reduce wind loads on heliostats. The tests investigated primarily the mean forces, moments, and the possibility of measuring fluctuating forces in anticipation of reducing those forces. A significant increase in ability to predict heliostat wind loads and their reduction within a heliostat field was achieved.

  10. Emissions Reduction Impact of Renewables

    E-Print Network [OSTI]

    Haberl, J. S.; Yazdani, B.; Culp, C.

    2012-01-01T23:59:59.000Z

    p. 1 Energy Systems Laboratory ? 2012 EMISSIONS REDUCTION IMPACT OF RENEWABLES October 2012 Jeff Haberl, Bahman Yazdani, Charles Culp Energy Systems Laboratory Texas A&M University p. 2 Energy Systems Laboratory ? 2012... Do TCEQ: Vince Meiller, Bob Gifford ERCOT: Warren Lasher USEPA: Art Diem, Julie Rosenberg ACKNOWLEDGEMENTS p. 3 Energy Systems Laboratory ? 2012 RENEWABLES Solar PV Solar Thermal Hydro Biomass Landfill Gas Geothermal p. 4...

  11. Jan Hendrik Bruinier II Anna von Pippich Fabrizio Andreatta -Milan, Italy II Massimo Bertolini -Essen, Germany II Siegfried Bcherer -

    E-Print Network [OSTI]

    Haller-Dintelmann, Robert

    Massimo Bertolini - Essen, Germany II Siegfried Böcherer - Mannheim, Germany II Thanasis Bouganis - Durham II Jay Jorgenson - New York, USA II Winfried Kohnen - Heidelberg, Germany II Jürg Kramer - Berlin, Germany II Siddarth Sankaran - Bonn, Germany II Maryna Viazovska - Bonn, Germany II Tonghai Yang - Madison

  12. Sliding friction in electrodeposited nanocrystalline Ni Alloys : transitional behavior associated with grain size, sliding speed, and contact stress.

    SciTech Connect (OSTI)

    Prasad, Somuri V.; Battaile, Corbett Chandler; Boyce, Brad Lee; Kotula, Paul Gabriel; Padilla, Henry A.

    2010-10-01T23:59:59.000Z

    Metallic materials in sliding contact typically undergo dislocation-mediated plasticity, which results in stick-slip frictional behavior associated with high coefficients of friction ({mu} > 0.8). Our recent work on two electroplated nanocrystalline Ni alloys reveal that under combined conditions of low stress and low sliding velocity, these metals have very low friction ({mu} < 0.3). The observed frictional behavior is consistent with the transition from dislocation-mediated plasticity to an alternative mechanism such as grain boundary sliding. Focused ion beam cross-sections viewed in the TEM reveal the formation of a subsurface tribological bilayer at the contact surface, where the parent nanocrystalline material has evolved in structure to accommodate the frictional contact. Grain growth at a critical distance below the contact surface appears to promote a shear-accomodation layer. We will discuss these results in the context of a grain-size dependent transition from conventional microcrystalline wear behavior to this unusual wear behavior in nanocrystalline FCC metals.

  13. Numerical calculation of dynamical friction in electron cooling systems, including magnetic field perturbations and finite time effects

    SciTech Connect (OSTI)

    Sobol, A.V.; Fedotov, A.; Bruhwiler, D.L.; Bell, G.I.; Litvinenko, V.

    2010-09-24T23:59:59.000Z

    The orders-of-magnitude higher luminosities required by future electron-ion collider concepts require a dissipative force to counteract the numerous factors acting to gradually increase the phase space volume of relativistic ion beams. High-energy electron cooling systems could provide the necessary dissipation via dynamical friction, but will have to be designed for new parameter regimes. It is expected that magnetic field errors, finite interaction time and other effects will reduce the dynamical friction and hence increase the cooling time, so improved understanding of the underlying dynamics is important. We present a generalized form of the classical field-free friction force equation, which conveniently captures some of these effects. Previous work (Bell et al 2008 J. Comput. Phys. 227 8714) shows both numerical and conceptual subtleties associated with undersampling of strong collisions, and we present a rigorous mathematical treatment of such difficulties, based on the use of a modified Pareto distribution for the electron-ion impact parameters. We also present a very efficient numerical algorithm for calculating the dynamical friction on a single ion in the field free case. For the case of arbitrary magnetic field errors, we present numerical simulation results, showing agreement with our generalized friction force formula.

  14. PARS II Training Workbook (Course 103) | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    PARS II Training Workbook (Course 103) PARS II Training Workbook (Course 103) PARS II More Documents & Publications PARS II TRAINING PARS II TRAINING PARS II 104 Contractor Monthly...

  15. Friction factor data for flat plate tests of smooth and honeycomb surfaces

    E-Print Network [OSTI]

    Ha, Tae Woong

    1989-01-01T23:59:59.000Z

    are needed. The purpose of this report is to present the air flow friction factor data for honeycomb surfaces (i.e., 1.57 mm, 0.79 mm and 0.51 mm in cell width, 3.81 mm and 2.29 mm in cell depth) with a flat plate tester. The flat plate tester is designed....2bar, and 17.9bar, respectively and 3 clearances between honeycombs which are 0.25mm, 0.38mm and 0.51mm. These clearance values are representative of actual seals used in the turbomachinary. The following questions wil l be answered: 1) Does...

  16. The influence of pore fluids on the frictional properties of quartzose sandstone

    E-Print Network [OSTI]

    Blackwell, Michael Lloyd

    1973-01-01T23:59:59.000Z

    the influence of pore fluids on the frictional properties of Tennessee and Coconino Sandstones, a series of triaxial compression tests have been performed. Specimens tested have been dry or they have contained kerosene, distilled water, or solutions of FeC1... Sandstone at different effective confining pressure. 19 Stress-shortening curves of four experiments performed with Tennessee Sandstone at 1 kb effective pressure: dry, saturated with kerosene, water, or 5x10 4 FeC13 solution. 21 Stress-shortening curves...

  17. Initial Development in Joining of ODS Alloys Using Friction Stir Welding

    SciTech Connect (OSTI)

    Ren, Weiju [ORNL; Feng, Zhili [ORNL

    2007-08-01T23:59:59.000Z

    Solid-state welding of oxide-dispersion-strengthened (ODS) alloy MA956 sheets using friction stir welding (FSW) was investigated. Butt weld was successfully produced. The weld and base metals were characterized using optical microscopy, scanning electronic microscopy, transmission electronic microscopy, and energy dispersion x-ray spectrum. Microhardness mapping was also conducted over the weld region. Analyses indicate that the distribution of the strengthening oxides was preserved in the weld. Decrease in microhardness of the weld was observed but was insignificant. The preliminary results seem to confirm the envisioned feasibility of FSW application to ODS alloy joining. For application to Gen IV nuclear reactor heat exchanger, further investigation is suggested.

  18. Determination of heat transfer and friction characteristics of an adapted inclined louvered fin

    SciTech Connect (OSTI)

    T'Joen, C.; Steeman, H.-J.; Willockx, A.; De Paepe, M. [Department of Flow, Heat and Combustion Mechanics, Ghent University-UGent, Sint-Pietersnieuwstraat 41, 9000 Gent (Belgium)

    2006-03-01T23:59:59.000Z

    An experimental study of a fin-and-tube heat exchanger was performed. To this end a test rig was constructed to measure the heat transfer rate on the air and waterside of the heat exchanger. A wide range of Reynolds numbers on the airside was investigated. The resulting data was used to determine the convective heat transfer correlation (expressed using the Colburn factor) and the friction factor on the airside. The fin type used in the heat exchanger of this research is an adaptation of the standard inclined louvered type. A thorough error analysis was performed, to validate the results. (author)

  19. Viscosity calculated in simulations of strongly coupled dusty plasmas with gas friction

    SciTech Connect (OSTI)

    Feng Yan; Goree, J.; Liu Bin [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

    2011-05-15T23:59:59.000Z

    A two-dimensional strongly coupled dusty plasma is modeled using Langevin and frictionless molecular dynamical simulations. The static viscosity {eta} and the wave-number-dependent viscosity {eta}(k) are calculated from the microscopic shear in the random motion of particles. A recently developed method of calculating the wave-number-dependent viscosity {eta}(k) is validated by comparing the results of {eta}(k) from the two simulations. It is also verified that the Green-Kubo relation can still yield an accurate measure of the static viscosity {eta} in the presence of a modest level of friction as in dusty plasma experiments.

  20. Statistically Steady Turbulence in Soap Films: Direct Numerical Simulations with Ekman Friction

    E-Print Network [OSTI]

    Prasad Perlekar; Rahul Pandit

    2008-11-09T23:59:59.000Z

    We present a detailed direct numerical simulation (DNS) designed to investigate the combined effects of walls and Ekman friction on turbulence in forced soap films. We concentrate on the forward-cascade regime and show how to extract the isotropic parts of velocity and vorticity structure functions and thence the ratios of multiscaling exponents. We find that velocity structure functions display simple scaling whereas their vorticity counterparts show multiscaling; and the probability distribution function of the Weiss parameter $\\Lambda$, which distinguishes between regions with centers and saddles, is in quantitative agreement with experiments.