Sample records for friction reduction ii

  1. Vehicle Technologies Office Merit Review 2015: Engine Friction Reduction – Part II (Base fluid and additive technologies)

    Broader source: Energy.gov [DOE]

    Presentation given by Argonne National Laboratory at 2015 DOE Hydrogen and Fuel Cells Program and vehicle technologies office annual merit review and peer evaluation meeting about engine friction...

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

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

    Friction Reduction Through Surface Finish and Coatings Engine Friction Reduction Through Surface Finish and Coatings Opportunities exist for friction reduction in piston rings and...

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

    Energy Savers [EERE]

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

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

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

    Steels 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...

  5. 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.

  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. Vehicle Technologies Office Merit Review 2015: Engine Friction Reduction Technologies

    Broader source: Energy.gov [DOE]

    Presentation given by Argonne National Laboratory at 2015 DOE Hydrogen and Fuel Cells Program and vehicle technologies office annual merit review and peer evaluation meeting about engine friction...

  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. Axis control using model predictive control: identification and friction effect reduction

    E-Print Network [OSTI]

    Boyer, Edmond

    Axis control using model predictive control: identification and friction effect reduction Pedro this numerical model is used to synthetize a predictive GPC controller reducing the impact of the friction Rodriguez-Ayerbe, Didier Dumur, Sylvain Lavernhe** * SUPELEC- E3S, Automatic Control, 3 rue Joliot Curie

  10. Pressure and partial wetting effects on superhydrophobic friction reduction in microchannel flow

    E-Print Network [OSTI]

    Hidrovo, Carlos H.

    Pressure and partial wetting effects on superhydrophobic friction reduction in microchannel flow://pof.aip.org/about/rights_and_permissions #12;PHYSICS OF FLUIDS 24, 112003 (2012) Pressure and partial wetting effects on superhydrophobic- ing that can lead to a superhydrophobic Cassie-Baxter state. The Cassie-Baxter state is characterized

  11. 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.

  12. 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

  13. 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

  14. 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 ...

  15. 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

  16. 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 DataDepartment of Energy Your Density Isn'tOrigin of Contamination in ManyDepartmentOutreach toTransmission and6/15/2015Energy Friction

  17. 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...

  18. 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 use this rig in the future to quantify frictional losses and improve on the efficiency of their diesel

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

    E-Print Network [OSTI]

    Johan S. Høye; I. Brevik

    2010-12-07T23:59:59.000Z

    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.

  20. 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.

  1. Towards approximate models of coulomb frictional moments in: I) revolute pin joints and II) spherical-socket ball joints

    E-Print Network [OSTI]

    -body contact configuration with various degrees of clearance. The proposed models can be used in the dynamic modelling and control of multi-body systems in frictional contact. Key words: Approximate frictional models and dynamic cases. The motivation for accurate modeling of frictional moments in these types of joints

  2. 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 ...

  3. 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

    . Jack H. Lunsford The catalytic activity of tetraamminecopper(II) complexes in aque- ous solution in the reduction of nitric oxide with ammonia nas been in- vestigated. Kinetic data for the nitric oxide reduction reaction were determined in a closed... circulating system. Electron paramagnetic reso- spectroscopy was used to determine the zelative quantity of copper in the +2 oxidation state at different temperatures. A reaction mechanism is proposed from these experimental investigations in order...

  4. 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.

  5. Numerical-analytical investigation into impact pipe driving in soil with dry friction. Part II: Deformable external medium

    E-Print Network [OSTI]

    Aleksandrova, Nadezhda

    2013-01-01T23:59:59.000Z

    Under analysis is travel of P-waves in an elastic pipe partly embedded in soil with dry friction. The mathematical formulation of the problem on impact pipe driving in soil is based on the model of axial vibration of an elastic bar, considering lateral resistance described using the law of solid dry friction. The author solves problems on axial load on pipe in interaction with external elastic medium, and compares the analytical and numerical results obtained with and without accounting for the external medium deformability.

  6. Solid friction between soft filaments

    E-Print Network [OSTI]

    Ward, Andrew; Schwenger, Walter; Welch, David; Lau, A W C; Vitelli, Vincenzo; Mahadevan, L; Dogic, Zvonimir

    2015-01-01T23:59:59.000Z

    Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin filaments, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments' overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes' drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. Our findings demonstrate how altering a filament's elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the prop...

  7. Solid friction between soft filaments

    E-Print Network [OSTI]

    Andrew Ward; Feodor Hilitski; Walter Schwenger; David Welch; A. W. C. Lau; Vincenzo Vitelli; L. Mahadevan; Zvonimir Dogic

    2015-03-04T23:59:59.000Z

    Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin filaments, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments' overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes' drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. Our findings demonstrate how altering a filament's elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials.

  8. Synthesis, Properties, and Reactions of Trinuclear Macrocyclic Nickel(II) and Nickel(I) Complexes: Electrocatalytic Reduction of CO2 by Nickel(II) Complex

    E-Print Network [OSTI]

    Paik Suh, Myunghyun

    FULL PAPER Synthesis, Properties, and Reactions of Trinuclear Macrocyclic Nickel(II) and Nickel(I) Complexes: Electrocatalytic Reduction of CO2 by Nickel(II) Complex Eun Young Lee,[a] Daewon Hong,[a] Han Woong Park,[a] and Myunghyun Paik Suh*[a] Keywords: Nickel / Macrocyclic compounds / Carbon dioxide

  9. 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 (

  10. Nickel(II) Complexes with Tetra-and Pentadentate Aminopyridine Ligands: Synthesis, Structure, Electrochemistry, and Reduction to

    E-Print Network [OSTI]

    Nazarenko, Alexander

    Nickel(II) Complexes with Tetra- and Pentadentate Aminopyridine Ligands: Synthesis, Structure, Electrochemistry, and Reduction to Nickel(I) Species Sergey V. Kryatov, B. Sharmila Mohanraj, Vladislav V. Tarasov A series of nickel(II) complexes with polydentate aminopyridine ligands N,N,N-tris-[2-(2-pyridyl

  11. 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.

  12. Heterogeneous Reduction of PuO2 with Fe(II): Importance of the Fe(III) Reaction Product

    SciTech Connect (OSTI)

    Felmy, Andrew R.; Moore, Dean A.; Rosso, Kevin M.; Qafoku, Odeta; Rai, Dhanpat; Buck, Edgar C.; Ilton, Eugene S.

    2011-05-01T23:59:59.000Z

    Abstract Heterogeneous reduction of actinides in higher and more soluble oxidation states to lower more insoluble oxidation states by reductants such as Fe(II) has been the subject of intensive study for more than two decades. However, Fe(II)-induced reduction of sparingly soluble Pu(IV) to the more soluble lower oxidation state Pu(III) has been much less studied even though such reactions can potentially increase the mobility of Pu in the subsurface. Thermodynamic calculations are presented that show how differences in the free energy of various possible solid-phase Fe(III) reaction products can greatly influence aqueous Pu(III) concentrations resulting from reduction of PuO2(am) by Fe(II). We present the first experimental evidence that reduction of PuO2(am) to Pu(III) by Fe(II) was enhanced when the Fe(III) mineral goethite was spiked into the reaction. The effect of goethite on reduction of Pu(IV) was demonstrated by measuring the time-dependence of total aqueous Pu concentration, its oxidation state, and system pe/pH. We also re-evaluated established protocols for determining Pu(III) [(Pu(III) + Pu(IV)) - Pu(IV)] by using thenoyltrifluoroacetone (TTA) in toluene extractions; the study showed that it is important to eliminate dissolved oxygen from the TTA solutions for accurate determinations. More broadly, this study highlights the importance of the Fe(III) reaction product in actinide reduction rate and extent by Fe(II).

  13. Standard test method for uranium in presence of plutonium by iron(II) reduction in phosphoric acid followed by chromium(VI) titration

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2002-01-01T23:59:59.000Z

    Standard test method for uranium in presence of plutonium by iron(II) reduction in phosphoric acid followed by chromium(VI) titration

  14. 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

  15. 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

    frequency equivalent viscous friction coefficient (Coulomb friction) equivalent viscous friction coefficient (hys', cretic friction) Young's modulus (psi) internal friction force per unit length (lbs) total shaft internal friction force (lbs... friction force is now generally believed to be hysteretic (resistance to elongation and contraction of material fibers, also called anelasticity) or Coulomb (relative motion between two materials at a joint) rather ihan viscous. In 1976, II. F. Black...

  16. 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

  17. 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.

  18. Quantum friction

    E-Print Network [OSTI]

    R. Tsekov

    2012-12-05T23:59:59.000Z

    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.

  19. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiation Protection RadiationRecord-SettingHead of ContractingofReducing WasteReduction

  20. 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

  1. 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,

  2. 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.

  3. 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

  4. 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 ...

  5. 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...

  6. 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

  7. 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.

  8. Energy Efficiency/ Renewable Energy Impact in The Texas Emissions Reduction Plan (TERP): Volume II- Technical Report

    E-Print Network [OSTI]

    Haberl, J.; Yazdani, B.; Lewis, C.; Liu, Z.; Baltazar, J. C.; Mukhopadhyay, J..; Degelman, L.; McKelvey, K.; Clardige, D.; Ellis, S.; Kim, H.; Zilbershtein. G.; Gilman, D.

    2012-01-01T23:59:59.000Z

    measures as a result of the TERP implementation. Sincerely, David E. Claridge, Ph.D., P.E. Director Enclosure cc: Commissioner Toby Baker Commissioner Carlos Rubinstein Executive Director Zak Covar 2011 TERP Report, Vol. II, p. 2...

  9. 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...

  10. 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.

  11. Rotational Quantum Friction

    E-Print Network [OSTI]

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

    2012-09-25T23:59:59.000Z

    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.

  12. 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.

  13. 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.

  14. Scale-selective turbulence reduction in H-mode plasmas in the TJ-II stellarator

    SciTech Connect (OSTI)

    Happel, T.; Conway, G. D.; Stroth, U. [Max-Planck-Institut fuer Plasmaphysik, Association Euratom-IPP, 85748 Garching (Germany); Estrada, T.; Blanco, E.; Hidalgo, C.; Collaboration: TJ-II Team

    2011-10-15T23:59:59.000Z

    Wavenumber spectra of density turbulence in L- and H-mode plasmas have been measured in the TJ-II stellarator by means of Doppler reflectometry. A pronounced suppression of the density fluctuation level is observed in H-mode close to the radial position of maximum radial electric field (E{sub r}) shear. Furthermore, intermediate scale density turbulence is reduced preferentially. This effect can be interpreted within the framework of vortex stretching feeding energy through Reynolds stress into zonal flows, while shear decorrelation of turbulent structures might not play a central role in TJ-II. Moreover, it is shown that in both L- and H-mode, the phase velocity of density fluctuations does not depend on the structure scale.

  15. Velocity tuning of friction with two trapped atoms

    E-Print Network [OSTI]

    Gangloff, Dorian; Counts, Ian; Jhe, Wonho; Vuleti?, Vladan

    2015-01-01T23:59:59.000Z

    Friction is the basic, ubiquitous mechanical interaction between two surfaces that results in resistance to motion and energy dissipation. In spite of its technological and economic significance, our ability to control friction remains modest, and our understanding of the microscopic processes incomplete. At the atomic scale, mismatch between the two contacting crystal lattices can lead to a reduction of stick-slip friction (structural lubricity), while thermally activated atomic motion can give rise to a complex velocity dependence, and nearly vanishing friction at sufficiently low velocities (thermal lubricity). Atomic force microscopy has provided a wealth of experimental results, but limitations in the dynamic range, time resolution, and control at the single-atom level have hampered a full quantitative description from first principles. Here, using an ion-crystal friction emulator with single-atom, single substrate-site spatial resolution and single-slip temporal resolution, we measure the friction force...

  16. Theory of Quantum Friction

    E-Print Network [OSTI]

    Mario G. Silveirinha

    2014-06-09T23:59:59.000Z

    Here, we develop a comprehensive quantum theory for the phenomenon of quantum friction. Based on a theory of macroscopic quantum electrodynamics for unstable systems, we calculate the quantum expectation of the friction force, and link the friction effect to the emergence of system instabilities related to the Cherenkov effect. These instabilities may occur due to the hybridization of particular guided modes supported by the individual moving bodies, and selection rules for the interacting modes are derived. It is proven that the quantum friction effect can take place even when the interacting bodies are lossless and made of nondispersive dielectrics.

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

    E-Print Network [OSTI]

    Haberl, J.; Yazdani, B.; Zilbershtein, G.; Baltazar, J. C.; Mukhopadhyay, J.; Clardige, D.; Parker, P.; Ellis, S.; Kim, H.; Gilman, D.; Degelman, L.

    2013-01-01T23:59:59.000Z

    &M University System Figure 1: OSD NOx Emissions Reduction Projections through 2020 (Base Year 2008) In 2012, (Table 1) the total integrated annual savings from all programs is 16,413,917 MWh/year. The integrated annual electricity savings... from all the different programs is: ? Savings from code-compliant residential and commercial construction is 498,883 MWh/year (3.0% of the total electricity savings), ? Savings from the PUC’s Senate Bill 7 program is 1,831,318 MWh/year (11...

  18. 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 ...

  19. 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

  20. Characterization of statistical prior image constrained compressed sensing (PICCS): II. Application to dose reduction

    SciTech Connect (OSTI)

    Lauzier, Pascal Theriault; Chen Guanghong [Medical Physics Department, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States)

    2013-02-15T23:59:59.000Z

    Purpose: The ionizing radiation imparted to patients during computed tomography exams is raising concerns. This paper studies the performance of a scheme called dose reduction using prior image constrained compressed sensing (DR-PICCS). The purpose of this study is to characterize the effects of a statistical model of x-ray detection in the DR-PICCS framework and its impact on spatial resolution. Methods: Both numerical simulations with known ground truth and in vivo animal dataset were used in this study. In numerical simulations, a phantom was simulated with Poisson noise and with varying levels of eccentricity. Both the conventional filtered backprojection (FBP) and the PICCS algorithms were used to reconstruct images. In PICCS reconstructions, the prior image was generated using two different denoising methods: a simple Gaussian blur and a more advanced diffusion filter. Due to the lack of shift-invariance in nonlinear image reconstruction such as the one studied in this paper, the concept of local spatial resolution was used to study the sharpness of a reconstructed image. Specifically, a directional metric of image sharpness, the so-called pseudopoint spread function (pseudo-PSF), was employed to investigate local spatial resolution. Results: In the numerical studies, the pseudo-PSF was reduced from twice the voxel width in the prior image down to less than 1.1 times the voxel width in DR-PICCS reconstructions when the statistical model was not included. At the same noise level, when statistical weighting was used, the pseudo-PSF width in DR-PICCS reconstructed images varied between 1.5 and 0.75 times the voxel width depending on the direction along which it was measured. However, this anisotropy was largely eliminated when the prior image was generated using diffusion filtering; the pseudo-PSF width was reduced to below one voxel width in that case. In the in vivo study, a fourfold improvement in CNR was achieved while qualitatively maintaining sharpness; images also had a qualitatively more uniform noise spatial distribution when including a statistical model. Conclusions: DR-PICCS enables to reconstruct CT images with lower noise than FBP and the loss of spatial resolution can be mitigated to a large extent. The introduction of statistical modeling in DR-PICCS may improve some noise characteristics, but it also leads to anisotropic spatial resolution properties. A denoising method, such as the directional diffusion filtering, has been demonstrated to reduce anisotropy in spatial resolution effectively when it was combined with DR-PICCS with statistical modeling.

  1. 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).

  2. 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.

  3. Frictional cooling of positively charged particles

    E-Print Network [OSTI]

    Daniel Greenwald; Allen Caldwell

    2011-11-14T23:59:59.000Z

    One of the focuses of research and development towards the construction of a muon collider is muon beam preparation. Simulation of frictional cooling shows that it can achieve the desired emittance reduction to produce high-luminosity muon beams. We show that for positively charged particles, charge exchange interactions necessitate significant changes to schemes previously developed for negatively charged particles. We also demonstrate that foil-based schemes are not viable for positive particles.

  4. Copper(II) imidazolate frameworks as highly efficient photocatalysts for reduction of CO{sub 2} into methanol under visible light irradiation

    SciTech Connect (OSTI)

    Li, Jingtian; Luo, Deliang; Yang, Chengju; He, Shiman; Chen, Shangchao; Lin, Jiawei; Zhu, Li; Li, Xin, E-mail: xinliscau@yahoo.com

    2013-07-15T23:59:59.000Z

    Three copper(II) imidazolate frameworks were synthesized by a hydrothermal (or precipitation) reaction. The catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), Fourier transform infrared spectra (FTIR), thermogravimetry (TG). Meanwhile, the photocatalytic activities of the samples for reduction of CO{sub 2} into methanol and degradation of methylene blue (MB) under visible light irradiation were also investigated. The results show that the as-prepared samples exhibit better photocatalytic activities for the reduction of carbon dioxide into methanol with water and degradation of MB under visible light irradiation. The orthorhombic copper(II) imidazolate frameworks with a band gap of 2.49 eV and green (G) color has the best photocatalytic activity for reduction of CO{sub 2} into methanol, 1712.7 ?mol/g over 5 h, which is about three times as large as that of monoclinic copper(II) imidazolate frameworks with a band gap 2.70 eV and blue (J) color. The degradation kinetics of MB over three photocatalysts fitted well to the apparent first-order rate equation and the apparent rate constants for the degradation of MB over G, J and P (with pink color) are 0.0038, 0.0013 and 0.0016 min{sup ?1}, respectively. The synergistic effects of smallest band gap and orthorhombic crystal phase structure are the critical factors for the better photocatalytic activities of G. Moreover, three frameworks can also be stable up to 250 °C. The investigation of Cu-based zeolitic imidazolate frameworks maybe provide a design strategy for a new class of photocatalysts applied in degradation of contaminations, reduction of CO{sub 2}, and even water splitting into hydrogen and oxygen under visible light. - Graphical abstract: Carbon dioxide was reduced into methanol with water over copper(II) imidazolate frameworks under visible light irradiation. - Highlights: • Three copper(II) imidazolate frameworks were first applied in the photo-reduction of CO{sub 2}. • The photocatalytic activities of the frameworks depend on their band gap and phase structures. • The photocatalytic activity of orthorhombic frameworks is 3 times that of monoclinic frameworks. • The degradation kinetics of MB over three photocatalysts followed the first-order rate equation. • The largest yield for reduction of CO{sub 2} into methanol on green framworks was 1712.7 ?mol/g over 5 h.

  5. 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.

  6. Nonlinear Dynamics of Dry Friction

    E-Print Network [OSTI]

    Franz-Josef Elmer

    1997-07-01T23:59:59.000Z

    The dynamical behavior caused by dry friction is studied for a spring-block system pulled with constant velocity over a surface. The dynamical consequences of a general type of phenomenological friction law (stick-time dependent static friction, velocity dependent kinetic friction) are investigated. Three types of motion are possible: Stick-slip motion, continuous sliding, and oscillations without sticking events. A rather complete discussion of local and global bifurcation scenarios of these attractors and their unstable counterparts is present.

  7. Nonlinear friction in quantum mechanics

    E-Print Network [OSTI]

    Roumen Tsekov

    2013-03-10T23:59:59.000Z

    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.

  8. 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.

  9. 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.

  10. MODELING AND ANALYSIS OF THE DYNAMICS OF DRY-FRICTION-DAMPED STRUCTURAL SYSTEMS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    MODELING AND ANALYSIS OF THE DYNAMICS OF DRY-FRICTION-DAMPED STRUCTURAL SYSTEMS by Olivier J . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2.1 Nonlinear methods for the analysis of friction-damped systems . . . . . . . . . . . . . . . . . . . . . . . . 15 II. HYBRID FREQUENCY-TIME DOMAIN METHODS FOR THE ANALYSIS OF COMPLEX STRUCTURAL SYSTEMS WITH DRY

  11. 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 of nanofluids in tube flow has been developed, instrumented and computerized. It has been calibrated using) nanofluids show peculiar results with substantial friction drag reduction and heat transfer enhancement

  12. 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.

  13. 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

  14. Energy Efficiency/Renewable Energy Impact in the Texas Emissions Reduction Plan (TERP), Vol. II - Technical Report

    E-Print Network [OSTI]

    Haberl, J. S.; Culp, C.; Yazdani, B.; Gilman, D.; Fitzpatrick, T.; Muns, S.; Verdict, M.; Ahmed, M.; Liu, Z.; Baltazar-Cervantes, J. C.; Degelman, L. O.; Turner, W. D.

    2006-11-01T23:59:59.000Z

    insight about improvement to the Emissions Reduction Calculator. Numerous additional individuals at the Laboratory contributed significantly to this report, including: Dr. David Claridge, Ms. Sherrie Hughes, Mr. Kelly Milligan, Mr. Jim Sweeney, Mr...

  15. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7111AWell:F E ,"^ I 1' . _ .t.fiom/ I'l7aaII

  16. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7111AWell:F E ,"^ I 1' . _ .t.fiom/ I'l7aaII

  17. II*

    Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613 122 40 Buildingto17 3400, U.S.MajorMarketsNov-14 Dec-14Has Hydrocarbon, a 1 II

  18. 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.

  19. 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.

  20. 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.

  1. Mesoscale Friction Anisotropy Revealed by Slidingless Tests

    SciTech Connect (OSTI)

    Annett, James [Trinity College; Gao, Yanfei [ORNL; Cross, Graham [Trinity College; Lucas, Barry N. [Fast Forward Devices, LLC.; Herbert, Erik G. [University of Tennessee, Knoxville (UTK)

    2011-01-01T23:59:59.000Z

    Using a recently developed multidimensional nanocontact system designed for a quantitative measurement of lateral contact stiffness in the 10-10{sup 6} N/m stiffness range (or 10-1000 nm contact size), we found a crystallographic-orientation-dependent lateral-stiffness reduction relative to the elastic prediction at contact sizes around 50 nm for polished Ni single crystal surface in air. The slidingless measurement is enabled by a frequency-specific, continuous stiffness measurement technique. Based on an interface microslip model and an anisotropic elastic contact analysis, the resulting friction stress is found to increase monotonically when the tested lateral direction rotates away from the closely packed direction.

  2. Energy Efficiency/Renewable Energy Impact in the Texas Emissions Reduction Plan (TERP), Vol. II - Technical Report 

    E-Print Network [OSTI]

    Haberl, J. S.; Culp, C.; Yazdani, B.; Gilman, D.; Fitzpatrick, T.; Muns, S.; Verdict, M.; Ahmed, M.; Liu, Z.; Baltazar-Cervantes, J. C.; Degelman, L. O.; Turner, W. D.

    2006-11-01T23:59:59.000Z

    , the following results were determined for energy-code compliant new residential single- and multi-family construction in non-attainment and affected counties built in 2004: ? The annual savings in 2005 amounted to 348,794 megawatt hours (MWh... would have been 1,799 MWh/day and 1,210 million Btu (MBtu) of natural gas, resulting in peak-OSD NOx emissions reductions of 1.26 tons (2007 eGRID). ? Beginning in 2005, the Laboratory worked with the TCEQ to integrate NOx emissions reductions (i...

  3. 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.

  4. Numerical Estimation of Frictional Torques with Rate and State Friction

    E-Print Network [OSTI]

    Arun K. Singh; T. N. Singh

    2015-01-20T23:59:59.000Z

    In this paper, numerical estimation of frictional torques is carried out of a rotary elastic disc on a hard and rough surface under different rotating conditions. A one dimensional spring- mass rotary system is numerically solved under the quasistatic condition with the rate and state dependent friction model. It is established that torque of frictional strength as well as torque of steady dynamic stress increases with radius and found to be maximum at the periphery of the disc. Torque corresponding to frictional strength estimated using the analytical solution matches closely with the simulation only in the case of high stiffness of the connecting spring. In steady relaxation simulation, a steadily rotating disc is suddenly stopped and relaxational angular velocity and corresponding frictional torque decreases with both steady angular velocity and stiffness of the connecting spring in the velocity strengthening regime. In velocity weakening regime, in contrast, torque of relaxation stress deceases but relaxation velocity increases. The reason for the contradiction is explained.

  5. 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...

  6. Evaluation of friction loss in flexible and galvanized duct 

    E-Print Network [OSTI]

    Zimmermann, Carlos Michael Alberto

    1985-01-01T23:59:59.000Z

    or similar exterior material. 3. When exterior abrasion of the duct can be a factor, a vinyl scuff strip can be glued or plastic welded in spiral fashion on the outside cover. 4. Reduction in flow because of Internal friction can be minimized by using...EVALUATION OF FRICTION LOSS IN FLEXIBLE AND GALVANIZED DUCT A Thesis by CARLOS MICHAEL ALBERTO ZIMMERMANN Submitted to the Graduate College of Texas A&M University in partial fulfliiment of the requirements for the degree of MASTER...

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Rubber friction on ice and snow surfaces 

    E-Print Network [OSTI]

    Skouvaklis, Gerasimos

    2011-06-28T23:59:59.000Z

    The friction of rubber on ice and snow surfaces is complex. Deeper scientific understanding is important for optimising performance of tyres in winter. Rubber, ice and snow systems exhibit frictional behaviour which ...

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. Dynamical friction on satellite galaxies

    E-Print Network [OSTI]

    Michiko Fujii; Yoko Funato; Junichiro Makino

    2006-06-23T23:59:59.000Z

    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.

  1. 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.

  2. 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

  3. Friction and Wear Reduction in Diesel Engine Valve Trains

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

    proprietary or confidential information Materials Science and Technology Division Oak Ridge National Laboratory DOE OVT MERIT REVIEW - February 26, 2008 Purpose of the Work *...

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

    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 DataDepartment of Energy Your Density Isn't Your Destiny:RevisedAdvisory Board ContributionsreductionRefineriesDepartmentPathwaySystems |

  5. 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 DataDepartment of Energy Your Density Isn't Your Destiny:RevisedAdvisoryStandard |inHVACEnforcementEngaging Students in EnergyDepartment

  6. 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 DataDepartment of Energy Your Density Isn't Your Destiny: The Future of1Albuquerque, NMPerformance |Should Know tothermoelectricDepartment

  7. 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 DataDepartment of Energy Your Density Isn't YourTransport(Fact Sheet), GeothermalGridHYDROGEN TO THEHudson

  8. 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.

  9. 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.

  10. Granular Brownian motion with dry friction

    E-Print Network [OSTI]

    A. Gnoli; A. Puglisi; H. Touchette

    2013-04-12T23:59:59.000Z

    The interplay between Coulomb friction and random excitations is studied experimentally by means of a rotating probe in contact with a stationary granular gas. The granular material is independently fluidized by a vertical shaker, acting as a 'heat bath' for the Brownian-like motion of the probe. Two ball bearings supporting the probe exert nonlinear Coulomb friction upon it. The experimental velocity distribution of the probe, autocorrelation function, and power spectra are compared with the predictions of a linear Boltzmann equation with friction, which is known to simplify in two opposite limits: at high collision frequency, it is mapped to a Fokker-Planck equation with nonlinear friction, whereas at low collision frequency, it is described by a sequence of independent random kicks followed by friction-induced relaxations. Comparison between theory and experiment in these two limits shows good agreement. Deviations are observed at very small velocities, where the real bearings are not well modeled by Coulomb friction.

  11. 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.

  12. The three different regimes in coulombic friction

    E-Print Network [OSTI]

    Azzouz Dermoune; Daoud Ounaissi; Nadji Rahmania

    2015-04-24T23:59:59.000Z

    de Gennes identified three regimes in the phenomenon of the Langevin equation wich includes Coulombic friction. Here we extend and precise this phenomenon to a constant external force.

  13. Skin friction for steel piles in sand

    E-Print Network [OSTI]

    Sulaiman, Ibrahim Hikmat

    1967-01-01T23:59:59.000Z

    MOVEMENT 4) For dry pile tests at initial void ratio of 0. 63, the assumption of a Coulomb type failure applies and the envelope is shown in Figure 23. The skin friction computed is the total friction caused by applied load. and. the static load caused... Sand 43 22. Skin Friction-Chamber Pressure Ratio Versus Pile Movement for Dense Dry Sand 44 23 ~ 24. Mohr Envelope for Skin Friction Measured. and Assumed. Pile Deformation 49 25 ~ Computed and Actual Load-Movement Curves for Test Pile 1 26...

  14. 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.

  15. Some Hamiltonian Models of Friction

    E-Print Network [OSTI]

    Juerg Froehlich; Zhou Gang; Avy Soffer

    2010-11-15T23:59:59.000Z

    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.

  16. 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,

  17. 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.

  18. 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.

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

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

    does not contain any proprietary or confidential information Friction Stir Spot Welding of Advanced High Strength Steels (AHSS) (13056 ORNL, 13055 PNNL) Friction Stir Spot...

  20. Friction forces on phase transition fronts

    E-Print Network [OSTI]

    Ariel Megevand

    2013-03-31T23:59:59.000Z

    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.

  1. Velocity dependence of friction of confined polymers

    E-Print Network [OSTI]

    I. M. Sivebaek; V. N. Samoilov; B. N. J. Persson

    2009-11-18T23:59:59.000Z

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate, and (b) polymer sliding on polymer. We discuss the velocity dependence of the frictional shear stress for both cases. In our simulations, the polymer films are very thin (approx. 3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all cases the frictional shear stress increases monotonically with the sliding velocity. For polymer sliding on polymer [case (b)] the friction is much larger, and the velocity dependence is more complex. For hydrocarbons with molecular lengths from 60 to 140 C-atoms, the number of monolayers of lubricant increases (abruptly) with increasing sliding velocity (from 6 to 7 layers), leading to a decrease of the friction. Before and after the layering transition, the frictional shear stresses are nearly proportional to the logarithm of sliding velocity. For the longest hydrocarbon (1400 C-atoms) the friction shows no dependence on the sliding velocity, and for the shortest hydrocarbon (20 C-atoms) the frictional shear stress increases nearly linearly with the sliding velocity.

  2. 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.

  3. 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

  4. 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...

  5. 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.

  6. 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

  7. Torsion Spring Oscillator with Dry Friction Eugene I. Butikov

    E-Print Network [OSTI]

    Butikov, Eugene

    by viscous and dry (Coulomb) friction are investigated analytically and with the help of computer simulations-state oscillations. 1. Introduction Mechanical vibration systems with combined viscous and dry (Coulomb) friction. Even the simplest dry friction model, the Coulomb friction, can explain the principal peculiarities

  8. On the velocity-strengthening behavior of dry friction

    E-Print Network [OSTI]

    Bar-Sinai, Yohai; Brener, Efim A; Bouchbinder, Eran

    2013-01-01T23:59:59.000Z

    The onset of frictional instabilities, e.g. earthquakes nucleation, is intimately related to velocity-weakening friction, in which the frictional resistance of interfaces decreases with increasing slip velocity. While this frictional response has been studied extensively, much less attention has been given to steady-state velocity-strengthening friction, in spite of its importance for various aspects of frictional phenomena such as the propagation speed of interfacial rupture fronts and the amount of stored energy released by them. In this note we suggest that a crossover from steady-state velocity-weakening friction at small slip velocities to steady-state velocity-strengthening friction at higher velocities might be a generic feature of dry friction. We further argue that while thermally activated rheology naturally gives rise to logarithmic steady-state velocity-strengthening friction, a crossover to stronger-than-logarithmic strengthening might take place at higher slip velocities, possibly accompanied by...

  9. Short-time Dynamics of Frictional Strength in Dry Friction O. Ben-David, G. Cohen and J. Fineberg

    E-Print Network [OSTI]

    Fineberg, Jay

    Short-time Dynamics of Frictional Strength in Dry Friction O. Ben-David, G. Cohen and J. Fineberg interface that separates two PMMA blocks in dry frictional contact. At applied shear forces significantly weakening 1. Introduction The short-time dynamics of dry friction are of fundamental interest in fields

  10. Short-time Dynamics of Frictional Strength in Dry Friction O. Ben-David and J. Fineberg

    E-Print Network [OSTI]

    Fineberg, Jay

    Short-time Dynamics of Frictional Strength in Dry Friction O. Ben-David and J. Fineberg The Racah that separates two PMMA blocks in dry frictional contact. At applied shear forces significantly below the static The short-time dynamics of dry friction are of fundamental interest in fields ranging from hard drive disk

  11. 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

    inertial and friction parameters of a lot of prototypes and industrial robots [1]- [10]. The kinematic

  12. 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.

  13. Quantum Cherenkov radiation and noncontact friction

    E-Print Network [OSTI]

    Golestanian, Ramin

    We present a number of arguments to demonstrate that a quantum analog of the Cherenkov effect occurs when two nondispersive half spaces are in relative motion. We show that they experience friction beyond a threshold ...

  14. 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.

  15. The Effect of Inner Surface Roughness on Friction Factor in Horizontal Micro-A. J. Ghajar1

    E-Print Network [OSTI]

    Ghajar, Afshin J.

    The Effect of Inner Surface Roughness on Friction Factor in Horizontal Micro- tubes A. J. Ghajar1 1 blood vessels, a sound understanding of fluid flow in micro- scale channels and tubes is required of the transition region. II. LITERATURE REVIEW To fully understand the flow phenomenon inside of micro-tubes

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

    E-Print Network [OSTI]

    Yves Pomeau; David C. Roberts

    2008-04-09T23:59:59.000Z

    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.

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Friction forces on atoms after acceleration

    E-Print Network [OSTI]

    Francesco Intravaia; Vanik E. Mkrtchian; Stefan Buhmann; Stefan Scheel; Diego A. R. Dalvit; Carsten Henkel

    2015-02-04T23:59:59.000Z

    The aim of this paper is to revisit the calculation of atom-surface quantum friction in the quantum field theory formulation put forward by Barton [New J. Phys. 12 (2010) 113045]. We show that the power dissipated into field excitations and the associated friction force depend on how the atom is boosted from being initially at rest to a configuration in which it is moving at constant velocity (v) parallel to the planar interface. In addition, we point out that there is a subtle cancellation between the one-photon and part of the two-photon dissipating power, resulting in a leading order contribution to the frictional power which goes as v^4. These results are also confirmed by an alternative calculation of the average radiation force, which scales as v^3.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  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. 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

  11. 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

  12. 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 can move in one dimension. We study the effect of friction on the design and performance of a feedback that a controller designed using a simple viscous friction model has poor performance - small amplitude oscillations

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. Penetration rate prediction for percussive drilling via dry friction model

    E-Print Network [OSTI]

    Krivtsov, Anton M.

    Penetration rate prediction for percussive drilling via dry friction model Anton M. Krivtsov a of percussive drilling assuming a dry friction mechanism to explain the experimentally observed drop in pene as a frictional pair, and this can generate the pattern of the impact forces close to reality. Despite quite

  1. 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 in systems presenting stick-slip due to dry friction has been under scrutiny 11 . Experimental evidence

  2. STUDIES OF THE DYNAMICS OF DRY-FRICTION-DAMPED BLADE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    STUDIES OF THE DYNAMICS OF DRY-FRICTION-DAMPED BLADE ASSEMBLIES by J er^ome Guillen A dissertation . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3 Multi-DOF systems with a single friction damper . . . . . . . 20 2.3.1 System model with multiple friction dampers . . . . . . 31 2.5 Conclusion

  3. 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

  4. ORIGINAL ARTICLE Frictional systems subjected to oscillating loads

    E-Print Network [OSTI]

    Barber, James R.

    ORIGINAL ARTICLE Frictional systems subjected to oscillating loads J. R. Barber Received: 3 and a generalized Hertzian contact problem with friction. Keywords Coulomb friction Á Shakedown Á Damping Á of appropriate interaction laws for use in the analysis of masonry structures [1] and for the discrete element

  5. A Simple Model on Granular Friction Hisao Hayakawa

    E-Print Network [OSTI]

    Hayakawa, Hisao

    observed even in atomic dry friction and and melt fractures in polymers [9,10]. Recently, Nasuno et al [11 for simulation of granular particles [13]. In particular, we 2 #12; regard Coulomb's friction law duringA Simple Model on Granular Friction Hisao Hayakawa Graduate School of Human and Environmental

  6. Torsion Spring Oscillator with Dry Friction Eugene Butikov

    E-Print Network [OSTI]

    Butikov, Eugene

    at investigation of free oscillations of a torsion spring pendulum damped by dry (Coulomb) friction. An idealizedTorsion Spring Oscillator with Dry Friction Manual Eugene Butikov Annotation. The manual includes as a prerequisite for the virtual lab "Torsion Spring Oscillator with Dry Friction." The manual includes also a set

  7. NUMERICAL APPROXIMATION OF P-SYSTEMS WITH COULOMB FRICTIONAL DAMPING

    E-Print Network [OSTI]

    to the precise nature of the dissipation. Dry (Coulomb) friction is a limit case that has not been fully analyzed in the presence of dry ­ Coulomb­ friction. A model is described in detail in Section 2. A discretizationNUMERICAL APPROXIMATION OF P-SYSTEMS WITH COULOMB FRICTIONAL DAMPING KRISTY COFFEY AND PIERRE A

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Shear Jamming in Granular Experiments without Basal Friction

    E-Print Network [OSTI]

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

    2014-08-08T23:59:59.000Z

    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.

  13. 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.

  14. Dynamics of Dry Friction: A Numerical Investigation

    E-Print Network [OSTI]

    Y. F. Lim; Kan Chen

    1998-03-18T23:59:59.000Z

    We perform extended numerical simulation of the dynamics of dry friction, based on a model derived from the phenomenological description proposed by T. Baumberger et al.. In the case of small deviation from the steady sliding motion, the model is shown to be equivalent to the state- and rate-dependent friction law which was first introduced by Rice and Ruina on the basis of experiments on rocks. We obtain the dynamical phase diagram that agrees well with the experimental results on the paper-on-paper systems. In particular, the bifurcation between stick-slip and steady sliding are shown to change from a direct (supercritical) Hopf type to an inverted (subcritical) one as the driving velocity increases, in agreement with the experiments.

  15. No quantum friction between uniformly moving plates

    E-Print Network [OSTI]

    T. G. Philbin; U. Leonhardt

    2009-03-26T23:59:59.000Z

    The Casimir forces between two plates moving parallel to each other are found by calculating the vacuum electromagnetic stress tensor. The perpendicular force between the plates is modified by the motion but there is no lateral force on the plates. Electromagnetic vacuum fluctuations do not therefore give rise to "quantum friction" in this case, contrary to previous assertions. The result shows that the Casimir-Polder force on a particle moving at constant speed parallel to a plate also has no lateral component.

  16. Low-energy muons via frictional cooling

    E-Print Network [OSTI]

    Yu Bao; Allen Caldwell; Daniel Greenwald; Guoxing Xia

    2010-01-18T23:59:59.000Z

    Low-energy muon beams are useful for a range of physics experiments. We consider the production of low-energy muon beams with small energy spreads using frictional cooling. As the input beam, we take a surface muon source such as that at the Paul Scherrer Institute. Simulations show that the efficiency of low energy muon production can potentially be raised to 1%, which is significantly higher than that of current schemes.

  17. 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.

  18. 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.

  19. On the velocity-strengthening behavior of dry friction

    E-Print Network [OSTI]

    Yohai Bar-Sinai; Robert Spatschek; Efim A. Brener; Eran Bouchbinder

    2014-04-15T23:59:59.000Z

    The onset of frictional instabilities, e.g. earthquakes nucleation, is intimately related to velocity-weakening friction, in which the frictional resistance of interfaces decreases with increasing slip velocity. While this frictional response has been studied extensively, less attention has been given to steady-state velocity-strengthening friction, in spite of its potential importance for various aspects of frictional phenomena such as the propagation speed of interfacial rupture fronts and the amount of stored energy released by them. In this note we suggest that a crossover from steady-state velocity-weakening friction at small slip velocities to steady-state velocity-strengthening friction at higher velocities might be a generic feature of dry friction. We further argue that while thermally activated rheology naturally gives rise to logarithmic steady-state velocity-strengthening friction, a crossover to stronger-than-logarithmic strengthening might take place at higher slip velocities, possibly accompanied by a change in the dominant dissipation mechanism. We sketch a few physical mechanisms that may account for the crossover to stronger-than-logarithmic steady-state velocity-strengthening and compile a rather extensive set of experimental data available in the literature, lending support to these ideas.

  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. Perchlorate reduction using electrochemically induced pitting corrosion of zero-valent titanium 

    E-Print Network [OSTI]

    Lee, Chun Woo

    2009-05-15T23:59:59.000Z

    reduced to chloride using electrochemically developed pitting corrosion on Ti(0). Perchlorate reduction was believed to be caused by an active reductant (dissolved Ti(II)) during the pitting corrosion of Ti(0). The rate of perchlorate reduction...

  2. 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

  3. 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

  4. 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.

  5. 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.

  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. 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....

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

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

    by reducing parasitic boundary regime friction losses and enable operation with lower viscosity oils while maintaining engine durability. deer08erck.pdf More Documents &...

  9. 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.

  10. Friction in a Model of Hamiltonian Dynamics

    E-Print Network [OSTI]

    Juerg Froehlich; Zhou Gang; Avy Soffer

    2011-11-01T23:59:59.000Z

    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. Abstract--Usually, the joint transmission friction model for robots is composed of a viscous friction force and of a constant

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    friction force and of a constant dry sliding friction force. However, according to the Coulomb law, the dry dynamic identification model for n degrees of freedom (dof) serial robot, where the dry sliding friction [1]-[10]. An approximation of the kinematic Coulomb friction, ( )CF sign q , is widely used to model

  12. 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

  13. 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...

  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. A Polynomial Chaos Approach to the Robust Analysis of the Dynamic Behaviour of Friction Systems

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    . Key word: Dry friction systems, Nonlinear dynamic systems, stability, limit cycle, robustness, uncertainty propagation, polynomial chaos, Lyapunov function, SOS programming. 1. Introduction Dry friction1 A Polynomial Chaos Approach to the Robust Analysis of the Dynamic Behaviour of Friction Systems

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

    E-Print Network [OSTI]

    Hossain, Quazi A

    1967-01-01T23:59:59.000Z

    termed "Coulomb friction" or dry friction. Merriam (26) differentiated it from "fluid friction" (that which occurs in the presence of a separating layer of lubricating fluid) and "internal friction" (that which resists e~ternal shear in a cohesionless... by many investigators, notably by de la Hire (17) and Euler (13) . The latter agreed with Amontons in giving to all surfaces a frictional coefficient of one third. The most systematic work on friction was done by Coulomb (12) . He examined a large...

  17. Thermal Modeling of A Friction Bonding Process

    SciTech Connect (OSTI)

    John Dixon; Douglas Burkes; Pavel Medvedev

    2007-10-01T23:59:59.000Z

    A COMSOL model capable of predicting temperature evolution during nuclear fuel fabrication is being developed at the Idaho National Laboratory (INL). Fuel plates are fabricated by friction bonding (FB) uranium-molybdenum (U-Mo) alloy foils positioned between two aluminum plates. The ability to predict temperature distribution during fabrication is imperative to ensure good quality bonding without inducing an undesirable chemical reaction between U-Mo and aluminum. A three-dimensional heat transfer model of the FB process implementing shallow pin penetration for cladding monolithic nuclear fuel foils is presented. Temperature distribution during the FB process as a function of fabrication parameters such as weld speed, tool load, and tool rotational frequency are predicted. Model assumptions, settings, and equations are described in relation to standard friction stir welding. Current experimental design for validation and calibration of the model is also demonstrated. Resulting experimental data reveal the accuracy in describing asymmetrical temperature distributions about the tool face. Temperature of the bonded plate drops beneath the pin and is higher on the advancing side than the retreating side of the tool.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  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. HOMOGENIZATION OF A VISCOELASTIC MATRIX IN LINEAR FRICTIONAL CONTACT

    E-Print Network [OSTI]

    Panchenko, Alexander

    is assumed to be dry, and the friction law is given by a version of Coulomb's law 1991 Mathematics Subject, 18, 17, 11]. The authors of these articles study the deformation of a body coming into frictional as normal compliance. The contact conditions of Coulomb type are formulated as inequalities involving

  6. Measurement of friction coefficients with the atomic force microscope

    E-Print Network [OSTI]

    Attard, Phil

    Measurement of friction coefficients with the atomic force microscope Phil Attard1, Johanna axial method for measuring the friction coefficient with the atomic force microscope is given measurement by measuring the difference between the constant compliance slopes of the extend and retract force

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

    , Kyle Marshall, Robert Stackhouse, Jason Cordes, Sherrie Hughes, Stephen O?Neal, Piljae Im, Soolyeon Cho, Mini Malhotra, and Sarah Phinney. 2008 TERP Report, Vol. II, p. 6 December 2009 Energy Systems Laboratory, Texas A&M University System...

  12. 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...

  13. 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.

  14. 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.

  15. 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.

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

    E-Print Network [OSTI]

    Rehmet, Joseph Don

    1970-01-01T23:59:59.000Z

    I M ? S IT U ME~c S UBEME6'T OF SKIN FRICTION PHD POINT BEARIiiG A Thesis JOS'- P':i QOij' REAMS T Suhmitted to th Gradua. e Colloa of Texas ASM Univer "it@ ln oar i! al f ul fl11ment of the requi ri ment for tha ~loc ~ ec of NP STE!3...-Situ Measurement of Skin Friction and Point Bearing (January 1970) Joseph D . Rehmet, B. S . , Texas A&M University Supervised by: Dr. Harry M. Coyle Field tests are made using several in-situ testing devices and limiting values of skin friction and point...

  17. The effect of Coulombic friction on spatial displacement statistics

    E-Print Network [OSTI]

    Menzel, Andreas M

    2010-01-01T23:59:59.000Z

    The phenomenon of Coulombic friction enters the stochastic description of dry friction between two solids and the statistic characterization of vibrating granular media. Here we analyze the corresponding Fokker-Planck equation including both velocity and spatial components, exhibiting a formal connection to a quantum mechanical harmonic oscillator in the presence of a delta potential. Numerical solutions for the resulting spatial displacement statistics show a crossover from exponential to Gaussian displacement statistics. We identify a transient intermediate regime that exhibits multiscaling properties arising from the contribution of Coulombic friction. These results are relevant to recent experimental studies of the displacement of colloidal particles along bilayer membrane tubes.

  18. The effect of Coulombic friction on spatial displacement statistics

    E-Print Network [OSTI]

    Andreas M. Menzel; Nigel Goldenfeld

    2011-06-23T23:59:59.000Z

    The phenomenon of Coulombic friction enters the stochastic description of dry friction between two solids and the statistic characterization of vibrating granular media. Here we analyze the corresponding Fokker-Planck equation including both velocity and spatial components, exhibiting a formal connection to a quantum mechanical harmonic oscillator in the presence of a delta potential. Numerical solutions for the resulting spatial displacement statistics show a crossover from exponential to Gaussian displacement statistics. We identify a transient intermediate regime that exhibits multiscaling properties arising from the contribution of Coulombic friction. The possible role of these effects during observations in diffusion experiments is shortly discussed.

  19. Critical scaling near jamming transition for frictional granular particles

    E-Print Network [OSTI]

    Michio Otsuki; Hisao Hayakawa

    2011-03-30T23:59:59.000Z

    The critical rheology of sheared frictional granular materials near jamming transition is numer- ically investigated. It is confirmed that there exist a true critical density which characterizes the onset of the yield stress, and two fictitious critical densities which characterize the scaling laws of rheological properties. We find the existence of a hysteresis loop between two of the critical densities for each friction coefficient. It is noteworthy that the critical scaling law for frictionless jamming transition seems to be still valid even for frictional jamming despite using fictitious critical density values.

  20. 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.

  1. 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.

  2. 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

  3. 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

  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. 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

  7. 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

  8. 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

  9. A liquid-crystal model for friction C.H. A. Cheng

    E-Print Network [OSTI]

    Shkoller, Steve

    for sliding friction. Dry friction between two sliding surfaces gen- erates granulation, resultingA liquid-crystal model for friction C.H. A. Cheng , L. H. Kellogg , S. Shkoller , and D. L, University of California, Davis, CA 95616 Contributed by D. L. Turcotte, November 19, 2007 Rate-and-state-friction

  10. High Friction from a Stiff Polymer Using Microfiber Arrays C. Majidi,1,* R. E. Groff,1

    E-Print Network [OSTI]

    Fearing, Ron

    2006) High dry friction requires intimate contact between two surfaces and is generally obtained using friction [1]. Dry friction of stiff polymers (E 1 GPa) [2,3] and rubbers [1,4,5] on glass is a wellHigh Friction from a Stiff Polymer Using Microfiber Arrays C. Majidi,1,* R. E. Groff,1 Y. Maeno,2 B

  11. 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 The differential equation of motion of an oscillator acted upon by dry friction: J ¨ = -D( + m) for > 0, J ¨ = -D cases in which the effects either of viscous friction or of dry friction predominate: a = 4m T = 4 m

  12. A rate and state friction law for saline ice Ben Lishman,1

    E-Print Network [OSTI]

    Feltham, Daniel

    coefficient of friction. This law describes dry friction. Bowden and Hughes [1939] proposed that the lowA rate and state friction law for saline ice Ben Lishman,1 Peter Sammonds,1,2 and Danny Feltham2 ice friction models are necessary to predict the nature of interactions between sea ice floes

  13. On the microphysical foundations of rate-and-state friction Thibaut Putelat,a,c

    E-Print Network [OSTI]

    Dawes, Jon

    -and-state formulation of dry friction is well established as a phenomenological yet quantitative description of dry in the evolution of frictional stick-slip processes. This overturned the classical idea of Coulomb frictionOn the microphysical foundations of rate-and-state friction Thibaut Putelat,a,c , Jonathan H. P

  14. Numerical analysis of a one-dimensional elastodynamic model of dry friction and unilateral contact

    E-Print Network [OSTI]

    Renard, Yves - Pôle de Mathématiques, Institut National des Sciences Appliquées de Lyon

    .e. hyperbolic) model with dry friction. Since we consider a Coulomb friction law with a slip velocity dependentNumerical analysis of a one-dimensional elastodynamic model of dry friction and unilateral contact in the numerical analysis of more elaborated dynamic purely elastic problems with dry friction. Ó 2001 Elsevier

  15. Coulomb and viscous friction fault detection with application to a pneumatic actuator

    E-Print Network [OSTI]

    Dunbar, William

    Coulomb and viscous friction fault detection with application to a pneumatic actuator W.B. Dunbar of friction (fault) presented in this paper could facilitate the compensation of dry friction in high precision position- ing mechanisms. Moreover, a fault detection technique for monitoring dry friction would

  16. 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.

  17. 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...

  18. On the friction coefficient of straight-chain aggregates

    E-Print Network [OSTI]

    Lorenzo Isella; Yannis Drossinos

    2011-01-31T23:59:59.000Z

    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.

  19. 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...

  20. 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...

  1. Structural connections in plywood friction-fit construction

    E-Print Network [OSTI]

    Wagner, Mali E. (Mali Esther)

    2014-01-01T23:59:59.000Z

    CNC mills allow precise fabrication of planar parts with embedded joinery which can be assembled into complex 3D geometries without the use of foreign mechanical fasteners. This thesis studies the behavior of the friction-fit ...

  2. Artificial Tribotactic Microscopic Walkers: Walking Based on Friction Gradients

    E-Print Network [OSTI]

    Steimel, Joshua P.

    Friction, the resistive force between two surfaces sliding past each other, is at the core of a wide diversity of locomotion schemes. While such schemes are well described for homogeneous environments, locomotion based on ...

  3. 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

  4. Small mass asymptotic for the motion with vanishing friction

    E-Print Network [OSTI]

    Mark Freidlin; Wenqing Hu; Alexander Wentzell

    2012-08-30T23:59:59.000Z

    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.

  5. The dependence of the dry friction threshold on rupture dynamics

    E-Print Network [OSTI]

    Ben-David, Oded

    2011-01-01T23:59:59.000Z

    The static friction coefficient between two materials is considered to be a material constant. We present experiments demonstrating that the ratio of shear to normal force needed to move contacting blocks can, instead, vary systematically with controllable changes in the external loading configuration. Large variations in both the friction coefficient and consequent stress drop are tightly linked to changes in the rupture dynamics of the rough interface separating the two blocks.

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

    E-Print Network [OSTI]

    Peternell Altamira, Luis E.

    2010-01-16T23:59:59.000Z

    ) ......................................................................................... 31 viii Page Figure 4.4: Coulomb and Viscous Friction block (TheMathWorks 2008) ...................... 33 Figure 4.5: SIMULINK model for verification of the SAP2000 friction damped brace model behavior... of the SAP2000 analytical model of the FDB .................................................... 33 Table 5.1: Peak interstory drift ratio of the different damper configurations subjected to the series of BSE-1 records...

  7. 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.

  8. Bar-halo Friction in Galaxies I: Scaling Laws

    E-Print Network [OSTI]

    J. A. Sellwood

    2005-09-28T23:59:59.000Z

    It has been known for some time that rotating bars in galaxies slow due to dynamical friction against the halo. However, recent attempts to use this process to place constraints on the dark matter density in galaxies and possibly also to drive dark matter out of the center have been challenged. This paper uses simplified numerical experiments to clarify several aspects of the friction mechanism. I explicitly demonstrate the Chandrasekhar scaling of the friction force with bar mass, halo density, and halo velocity dispersion. I present direct evidence that exchanges between the bar and halo orbits at major resonances are responsible for friction and study both individual orbits and the net changes at these resonances. I also show that friction alters the phase space density of particles in the vicinity of a major resonance, which is the reason the magnitude of the friction force depends on the prior evolution. I demonstrate that bar slow down can be captured correctly in simulations having modest spatial resolution and practicable numbers of particles. Subsequent papers in this series delineate the dark matter density that can be tolerated in halos of different density profiles.

  9. Spindown of magnetars: Quantum Vacuum Friction?

    E-Print Network [OSTI]

    Xiong, Xue-Yu; Xu, Ren-Xin

    2015-01-01T23:59:59.000Z

    Magnetars are proposed to be peculiar neutron stars which could power their X-ray radiation by super-strong magnetic fields as high as $\\gtrsim 10^{14}$ G. However, no direct evidence for such strong fields is obtained till now, and the recent discovery of low magnetic field magnetars even indicates that some more efficient radiation mechanism than magnetic dipole radiation should be included. % In this paper, quantum vacuum friction (QVF) is suggested to be a direct consequence of super-strong {\\em surface} fields, therefore the magnetar model could then be tested further through the QVF braking. % Pulsars interact with the quantum vacuum in high surface magnetic field, which results in a significantly high spindown rate ( $\\dot{P}$ ). It is found that QVF dominates the energy loss of pulsars when $B_{\\rm surf}\\cdot P>10^{11}(10^{10})$G$\\cdot$s if the ratio $\\xi$ of the surface magnetic field over diploe magnetic field is 10(100), with $B_{\\rm surf}$ the surface magnetic field and $P$ the rotation period. % ...

  10. 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.

  11. 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.

  12. 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

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

    E-Print Network [OSTI]

    Buscaglia, Gustavo C.

    of an infinitely-wide pad, subject to a constant load and sliding at constant speed on a runner with transverseU function characterizing the pad profile 1 #12;m pad linear mass per unit width p hydrodynamic pressure width H non-dimensionalization length for z, Z and e R curvature radius of the pad's profile U non

  14. 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 DataDepartment of Energy Your Density Isn't YourTransport inEnergy0.pdf Flash2010-60.pdf2 DOE March, 20152LLCDepartment ofDepartment

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

    E-Print Network [OSTI]

    Alfred Hucht

    2009-11-04T23:59:59.000Z

    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.

  16. Non-Contact Friction for Ion-Surface Interactions

    E-Print Network [OSTI]

    U. D. Jentschura; G. Lach

    2015-04-21T23:59:59.000Z

    Non-contact friction forces are exerted on physical systems through dissipative processes, when the two systems are not in physical contact with each other, or, in quantum mechanical terms, when the overlap of their wave functions is negligible. Non-contact friction is mediated by the exchange of virtual quanta, with the additional requirement that the scattering process needs to have an inelastic component. For finite-temperature ion-surface interactions, the friction is essentially caused by Ohmic resistance due to the motion of the image charge moving in a dielectric material. A conceivable experiment is difficult because the friction force needs to be isolated from the interaction with the image charge, which significantly distorts the ion's flight path. We propose an experimental setup which is designed to minimize the influence of the image charge interaction though a compensation mechanism, and evaluate the energy loss due to non-contact friction for helium ions (He+) interacting with gold, vanadium, titanium and graphite surfaces. Interactions with the infinite series of mirror charges in the plates are summed in terms of the logarithmic derivatives of the Gamma function, and of the Hurwitz zeta function.

  17. Investigation of Skin Tribology and Its Effects on Coefficient of Friction and Other Tactile Attributes Involving Polymer Applications 

    E-Print Network [OSTI]

    Darden, Matthew Aguirre

    2012-02-14T23:59:59.000Z

    concerning tactility, examining environmental and material properties that affect skin on fabric coefficient of friction. In this study, similar friction procedure was used to compare coefficients of friction of a fingerpad across varying polymer fabrics...

  18. 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

    2014-07-24T23:59:59.000Z

    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.

  19. Dry Friction Avalanches: Experiment and Robin Hood model

    E-Print Network [OSTI]

    Sergey V. Buldyrev; John Ferrante; Fredy R. Zypman

    2005-11-01T23:59:59.000Z

    This paper presents experimental evidence and theoretical models supporting that dry friction stick-slip is described by self-organized criticality. We use the data, obtained with a pin-on-disc tribometer set to measure lateral force to examine the variation of the friction force as a function of time. We study nominally flat surfaces of aluminum and steel. The probability distribution of force jumps follows a power law with exponents $\\mu$ in the range 2.2 -- 5.4. The frequency power spectrum follows a $1/{f^\\alpha}$ pattern with $\\alpha$ in the range 1 -- 2.6. In addition, we present an explanation of these power-laws observed in the dry friction experiments based on the Robin Hood model of self organized criticality. We relate the values of the exponents characterizing these power laws to the critical exponents $D$ an $\

  20. Quantum Friction: Cooling Quantum Systems with Unitary Time Evolution

    E-Print Network [OSTI]

    Aurel Bulgac; Michael McNeil Forbes; Kenneth J. Roche; Gabriel Wlaz?owski

    2013-05-29T23:59:59.000Z

    We introduce a type of quantum dissipation -- local quantum friction -- by adding to the Hamiltonian a local potential that breaks time-reversal invariance so as to cool the system. Unlike the Kossakowski-Lindblad master equation, local quantum friction directly effects unitary evolution of the wavefunctions rather than the density matrix: it may thus be used to cool fermionic many-body systems with thousands of wavefunctions that must remain orthogonal. In addition to providing an efficient way to simulate quantum dissipation and non-equilibrium dynamics, local quantum friction coupled with adiabatic state preparation significantly speeds up many-body simulations, making the solution of the time-dependent Schr\\"odinger equation significantly simpler than the solution of its stationary counterpart.

  1. 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.

  2. 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

  3. 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...

  4. Identification and compensation of friction for a dual stage positioning system

    E-Print Network [OSTI]

    Thimmalapura, Satish Voddina

    2005-11-01T23:59:59.000Z

    and velocity as compared to conventional friction models which are dependent on the direction of motion. Static and Coulomb friction were modelled as functions of velocity and position. This model was able to predict the behavior of the coarse stage...

  5. Numerical Study on Transverse Friction of a Slender Rod Contacting the Seabed

    E-Print Network [OSTI]

    Lu, Hang

    2012-10-19T23:59:59.000Z

    based upon a Coulomb model originally developed for the simulation of the friction in all dry contact mechanical systems. In applying the Coulomb model, the transverse friction depends on the transverse displacement and/or velocity of a slender rod...

  6. THE DYNAMICS OF A RAILWAY WAGON WHEEL SET WITH DRY FRICTION DAMPING

    E-Print Network [OSTI]

    stick-slip and hysteresis in our model of the dry friction and assume that Coulomb's friction law holds-rail interaction and this simplicity might be a contributing factor to the derailments. In this article a more

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. Finite-element modeling of subglacial cavities and related friction law

    E-Print Network [OSTI]

    Gagliardini, Olivier

    Finite-element modeling of subglacial cavities and related friction law O. Gagliardini,1 D. Cohen,2, the friction law, can be easily extended from linear to nonlinear ice rheology and is bounded even for bedrocks with locally infinite slopes. Combining our results with earlier works by others, a phenomenological friction

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. Dense granular ows: two-particle argument accounts for friction-like constitutive law with threshold

    E-Print Network [OSTI]

    Recanati, Catherine

    robust scaling behav- iors in various ow geomerties for dry grains, whether frictional or not [2, 4Dense granular ows: two-particle argument accounts for friction-like constitutive law a constitutive law that exhibits a ow threshold expressed as a #12;nite e#11;ective friction at ow onset

  12. Method for measurement of friction forces on single cells in microfluidic devices

    E-Print Network [OSTI]

    Ma, Hongshen

    both dry and wet conditions, are well estab- lished.16,17 The measurement of friction at micrometer the friction between dry microscopic surfaces, including atomic force microscopy, fric- tion-force microscopyMethod for measurement of friction forces on single cells in microfluidic devices Lazar

  13. Firstpassage time of Brownian motion with dry friction Yaming Chen 1, # and Wolfram Just 1, +

    E-Print Network [OSTI]

    Just, Wolfram

    First­passage time of Brownian motion with dry friction Yaming Chen 1, # and Wolfram Just 1, + 1­smooth stochastic model, namely Brownian motion with dry friction, using two di#erent but closely related approaches on the other. For the simple case containing only dry friction, a phase transi­ tion phenomenon in the spectrum

  14. Progress of Theoretical Physics Supplement 1 Simulation of granular friction and its effective theory

    E-Print Network [OSTI]

    Hayakawa, Hisao

    sliding of the plate. Similar behaviors have been observed even in atomic dry friction 4) and meltProgress of Theoretical Physics Supplement 1 Simulation of granular friction and its effective­8501 (Received ) This paper discusses the application of the distinct element method (DEM) for granular friction

  15. An analytical approach to codimension2 sliding bifurcations in the dry friction oscillator

    E-Print Network [OSTI]

    An analytical approach to codimension­2 sliding bifurcations in the dry friction oscillator M In this paper, we consider analytically sliding bifurcations of periodic orbits in the dry friction oscillator] for a detailed account of these bifurcations in the case of periodic orbits. The dry friction oscillator

  16. ensl-00178753,version1-12Oct2007 Friction and dilatancy in immersed granular matter.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -measurements in the dry case [8], G´eminard et al. brought to the fore a dynamic friction- coefficient µ in the caseensl-00178753,version1-12Oct2007 Friction and dilatancy in immersed granular matter. T. Divoux'Italie, 69364 Lyon cedex 07, France. The friction of a sliding plate on a thin immersed granular layer obeys

  17. An analytical approach to codimension-2 sliding bifurcations in the dry friction oscillator

    E-Print Network [OSTI]

    Politècnica de Catalunya, Universitat

    An analytical approach to codimension-2 sliding bifurcations in the dry friction oscillator M consider analytically sliding bifurcations of periodic orbits in the dry friction oscillator. The system of periodic orbits. The dry friction oscillator is a very good example of a nonsmooth system containing

  18. Dry Friction and Impact Dynamics in Railway Vehicles Dan Erik Petersen Mark Hoffmann

    E-Print Network [OSTI]

    Dry Friction and Impact Dynamics in Railway Vehicles Dan Erik Petersen Mark Hoffmann c973539 c Piotrowski. This model successfully takes into account damping due to dry friction in the suspension links due to dry friction. The wheelsets are constrained by guidance structures of the freight wagon

  19. Adhesion and Anisotropic Friction Enhancements of Angled Heterogeneous Micro-Fiber Arrays with

    E-Print Network [OSTI]

    Goldstein, Seth Copen

    in a synthetic dry angled fibrillar adhesive sample (spatula tip fiber sample). The direction dependent frictionAdhesion and Anisotropic Friction Enhancements of Angled Heterogeneous Micro-Fiber Arrays and spatula shaped tips via dipping. These fibers are characterized for adhesion and friction and compared

  20. LETTER doi:10.1038/nature13202 Classical shear cracks drive the onset of dry frictional

    E-Print Network [OSTI]

    Fineberg, Jay

    LETTER doi:10.1038/nature13202 Classical shear cracks drive the onset of dry frictional motion Ilya contactsdefiningafrictionalinterface3,4 . Therearea varietyofviews on how best to describe the onset of dry frictional motion the interface. We investigated the onset of dry frictional motion by per- forming simultaneous high

  1. Study of a transition in the qualitative behaviour of a simple oscillator with Coulomb friction

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    in the following way: when a system involving unilateral contact and dry friction is submitted to an oscillatingStudy of a transition in the qualitative behaviour of a simple oscillator with Coulomb friction. Keywords Coulomb friction, equilibrium states, mass-spring systems, nonsmooth dynamics. 1 Introduction

  2. An efficient scheme on wet/dry transitions for Shallow Water Equations with friction Christophe Berthona

    E-Print Network [OSTI]

    Coudière, Yves

    An efficient scheme on wet/dry transitions for Shallow Water Equations with friction Christophe discrepancy between both source terms comes from their relevance in dry regions. Indeed, the friction term the friction source terms in the shallow-water model. Such additional source terms are known to be very stiff

  3. Transition from Thermal to Athermal Friction under Cryogenic Conditions Xueying Zhao (),1

    E-Print Network [OSTI]

    Sawyer, Wallace

    the strong dependence of friction on temperature under cryogenic and dry sliding conditions in termsTransition from Thermal to Athermal Friction under Cryogenic Conditions Xueying Zhao (),1 Simon R manuscript received 3 April 2009; published 5 May 2009) Atomic scale frictional forces encountered

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

    E-Print Network [OSTI]

    Le-Bot, Alain

    Experimental study of friction noise of dry contact under light load A. Le Bot ­ H. Ben Abdelounis of friction noise radiated from the contact area of two sliding solids. The domain of interest is dry contact, that is the friction sound aris- ing when two dry and rough surfaces are rubbed on each other under light normal load

  5. Tribol Lett Thermal -Induced Wear Mechanisms of Sheet Nacre in Dry Friction

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Tribol Lett 1 Thermal - Induced Wear Mechanisms of Sheet Nacre in Dry Friction Philippe Stempfléa on the wear of sheet nacre by the assessment of the thermal component of the friction with a scanning thermal because the friction-induced thermal component is not sufficient for degrading the organic matrices

  6. Stick-slip friction and nucleation dynamics of ultrathin liquid films I. S. Aranson,1

    E-Print Network [OSTI]

    Hasty, Jeff

    yield stress leading to stick-slips similar to that in solid-on-solid dry friction processes5Stick-slip friction and nucleation dynamics of ultrathin liquid films I. S. Aranson,1 L. S'' of the confined fluid. This model successfully accounts for the observed phenomenology of friction in ultrathin

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

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -conservative mechanical systems is proposed. In particular, dry-friction non-linearities are considered although degrees-of-freedom example featuring dry-friction illustrates the method and highlights the effects of a turbomachinery blade, with dry-friction interfaces is proposed. In the latter, an original framework

  8. 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

  9. 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

  10. 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

  11. 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

  12. Shakedown of coupled two-dimensional discrete frictional systems Young Ju Ahn a

    E-Print Network [OSTI]

    Daly, Samantha

    that Melan's theorem can be applied to discrete elastic systems governed by the Coulomb friction law only systems. & 2008 Elsevier Ltd. All rights reserved. 1. Introduction The classical Coulomb friction law with the Coulomb friction law. These parallels and experience with the solution of specific example problems have

  13. 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 is eventually dissipated due to surface friction. Since the energy production rate is a linear function while frictional dissipation rate balances the energy production rate near the radius of maximum wind (RMW

  14. 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 is eventually dissipated due to surface friction. Since the energy production rate is a linear function while frictional dissipation rate balances the energy production rate near the radius of maximum wind (RMW

  15. A Nonsmooth Newton Solver for Capturing Exact Coulomb Friction in Fiber Assemblies

    E-Print Network [OSTI]

    A Nonsmooth Newton Solver for Capturing Exact Coulomb Friction in Fiber Assemblies FLORENCE in a stable way, and approximate Coulombs's friction law for making the problem tractable. In contrast- act Coulomb friction as a zero finding problem of a nonsmooth function. A semi-implicit time

  16. Dependence of friction on roughness, velocity, and temperature Martin Dub,2

    E-Print Network [OSTI]

    Grant, Martin

    - faces were discovered long ago by Da Vinci, Amonton, and Coulomb. They found that friction is i, and friction at the macroscopic level is now well understood, for both dry rough 3 and lubricated surfaces 4Dependence of friction on roughness, velocity, and temperature Yi Sang,1 Martin Dubé,2 and Martin

  17. About contacts of adhesive, elasto-plastic, frictional powders Stefan Luding

    E-Print Network [OSTI]

    Luding, Stefan

    , for more details see [4; 8]. Adhesive Contact Model For fine dry particles [9], not only frictionAbout contacts of adhesive, elasto-plastic, frictional powders Stefan Luding Multi Scale Mechanics). The contact mechanics used involves elasto-plastic, viscous, frictional, and torque contributions. From

  18. Experimental evidence of flutter and divergence instabilities induced by dry friction

    E-Print Network [OSTI]

    Bigoni, Davide

    Experimental evidence of flutter and divergence instabilities induced by dry friction Davide Bigoni structures with Coulomb friction, but no direct experimental evidence has ever been provided. Moreover Coulomb friction and how this, in full agreement with the theory, can induce a blowing-up vibrational

  19. A Hybrid Iterative Solver for Robustly Capturing Coulomb Friction in Hair Dynamics

    E-Print Network [OSTI]

    A Hybrid Iterative Solver for Robustly Capturing Coulomb Friction in Hair Dynamics Gilles Daviet-slip instabilities. See the accompanying video for the full animations. Abstract Dry friction between hair fibers a hybrid strategy that combines a new zero-finding formulation of (exact) Coulomb friction together

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

    E-Print Network [OSTI]

    Luding, Stefan

    and Coulomb friction. In the simplest case visco-elastic rules can be imposed at each contact, differentFrictional powders: Ratcheting under periodic strain in 3D S. Luding1 , C. T. David2 , R. Garcia of friction leads to a transition from ratcheting to shake-down, i.e., the accumulation of strain stops

  1. 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.

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

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2010-09-15T23:59:59.000Z

    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.

  3. Friction stir method for forming structures and materials

    DOE Patents [OSTI]

    Feng, Zhili (Knoxville, TN); David, Stan A. (Knoxville, TN); Frederick, David Alan (Harriman, TN)

    2011-11-22T23:59:59.000Z

    Processes for forming an enhanced material or structure are disclosed. The structure typically includes a preform that has a first common surface and a recess below the first common surface. A filler is added to the recess and seams are friction stir welded, and materials may be stir mixed.

  4. 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

  5. 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.

  6. 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.

  7. ccsd00000893 Sliding Friction at a Rubber/Brush Interface

    E-Print Network [OSTI]

    ccsd­00000893 (version 1) : 28 Nov 2003 Sliding Friction at a Rubber/Brush Interface Lionel Bureau(dimethylsiloxane) (PDMS) rubber network sliding, at low velocity, on a substrate on which PDMS chains are end-tethered. We studied the behaviour of such rubber/brush interfaces at high sliding velocities and showed

  8. 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.

  9. The influence of internal friction on rotordynamic instability 

    E-Print Network [OSTI]

    Srinivasan, Anand

    2004-09-30T23:59:59.000Z

    Internal friction has been known to be a cause of whirl instability in built-up rotors since the early 1900's. This internal damping tends to make the rotor whirl at shaft speeds greater than a critical speed, the whirl speed usually being equal...

  10. 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.

  11. 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

  12. 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.

  13. Confined flow of suspensions modeled by a frictional rheology

    E-Print Network [OSTI]

    Brice Lecampion; Dmitry I. Garagash

    2014-09-19T23:59:59.000Z

    We investigate in detail the problem of confined pressure-driven laminar flow of neutrally buoyant non-Brownian suspensions using a frictional rheology based on the recent proposal of Boyer et al., 2011. The friction coefficient and solid volume fraction are taken as functions of the dimensionless viscous number I defined as the ratio between the fluid shear stress and the particle normal stress. We clarify the contributions of the contact and hydrodynamic interactions on the evolution of the friction coefficient between the dilute and dense regimes reducing the phenomenological constitutive description to three physical parameters. We also propose an extension of this constitutive law from the flowing regime to the fully jammed state. We obtain an analytical solution of the fully-developed flow in channel and pipe for the frictional suspension rheology. The result can be transposed to dry granular flow upon appropriate redefinition of the dimensionless number I. The predictions are in excellent agreement with available experimental results, when using the values of the constitutive parameters obtained independently from stress-controlled rheological measurements. In particular, the frictional rheology correctly predicts the transition from Poiseuille to plug flow and the associated particles migration with the increase of the entrance solid volume fraction. We numerically solve for the axial development of the flow from the inlet of the channel/pipe toward the fully-developed state. The available experimental data are in good agreement with our predictions. The solution of the axial development of the flow provides a quantitative estimation of the entrance length effect in pipe for suspensions. A analytical expression for development length is shown to encapsulate the numerical solution in the entire range of flow conditions from dilute to dense.

  14. 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.

  15. 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.

  16. 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

  17. Texture-Induced Modulations of Friction Force: The Fingerprint Effect E. Wandersman, R. Candelier, G. Debregeas, and A. Prevost*

    E-Print Network [OSTI]

    Debrégeas, Georges

    2011) Modulations of the friction force in dry solid friction are usually attributed to macroscopicTexture-Induced Modulations of Friction Force: The Fingerprint Effect E. Wandersman, R. Candelier's main ingredient is the nonlinearity of the friction law. Since such nonlinearity is ubiquitous for soft

  18. Turbulent drag reduction through oscillating discs

    E-Print Network [OSTI]

    Wise, Daniel J

    2014-01-01T23:59:59.000Z

    The changes of a turbulent channel flow subjected to oscillations of wall flush-mounted rigid discs are studied by means of direct numerical simulations. The Reynolds number is $R_\\tau$=$180$, based on the friction velocity of the stationary-wall case and the half channel height. The primary effect of the wall forcing is the sustained reduction of wall-shear stress, which reaches a maximum of 20%. A parametric study on the disc diameter, maximum tip velocity, and oscillation period is presented, with the aim to identify the optimal parameters which guarantee maximum drag reduction and maximum net energy saving, computed by taking into account the power spent to actuate the discs. This may be positive and reaches 6%. The Rosenblat viscous pump flow is used to predict the power spent for disc motion in the turbulent channel flow and to estimate localized and transient regions over the disc surface subjected to the turbulent regenerative braking effect, for which the wall turbulence exerts work on the discs. The...

  19. 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.

  20. 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

    2004-10-01T23:59:59.000Z

    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.

  1. Un-reduction

    E-Print Network [OSTI]

    Martins Bruveris; David C. P. Ellis; Francois Gay-Balmaz; Darryl D. Holm

    2015-04-08T23:59:59.000Z

    This paper provides a full geometric development of a new technique called un-reduction, for dealing with dynamics and optimal control problems posed on spaces that are unwieldy for numerical implementation. The technique, which was originally concieved for an application to image dynamics, uses Lagrangian reduction by symmetry in reverse. A deeper understanding of un-reduction leads to new developments in image matching which serve to illustrate the mathematical power of the technique.

  2. 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."

  3. 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.

  4. 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.

  5. 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.

  6. Friction Factor Measurements in an Equally Spaced Triangular Tube Array

    SciTech Connect (OSTI)

    Vassallo P, Symolon P

    2007-03-19T23:59:59.000Z

    Friction factor data for adiabatic cross-flow of water in a staggered tube array was obtained over a Reynolds number range (based on hydraulic diameter and gap velocity) of about 10,000 to 250,000. The tubes were 12.7mm (0.5 inch) outer diameter, in a uniformly spaced triangular arrangement with a pitch-to-diameter ratio of 1.5. The friction factor was compared to several literature correlations, and was found to be best matched by the Idelchik correlation. Other correlations were found to vary significantly from the test data. Based on the test data, a new correlation is proposed for this tube bundle geometry which covers the entire Reynolds number range tested.

  7. Quantum Vacuum Friction in Highly Magnetized Neutron Stars

    E-Print Network [OSTI]

    Arnaud Dupays; Carlo Rizzo; Dimitar Bakalov; Giovanni F. Bignami

    2008-04-25T23:59:59.000Z

    In this letter we calculate the energy loss of highly magnetized neutron star due to friction with quantum vacuum, namely Quantum Vacuum Friction (QVF). Taking into account one-loop corrections in the effective Heisenberg-Euler Lagrangian of the light-light interaction, we derive an analytic expression for QVF allowing us to consider magnetic field at the surface of the star as high as $10^{11} $T. In the case of magnetars with high magnetic field above the QED critical field, we show that the energy loss by QVF dominates the energy loss process. This has important consequences, in particular on the inferred value of the magnetic field. This also indicates the need for independent measurements of magnetic field, energy loss rate, and of the braking index to fully characterize magnetars.

  8. 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.

  9. Kinetics of Fe(III)*EDTA reduction by ascorbic acid

    SciTech Connect (OSTI)

    Li, W.; Harkness, J.B.L.; Mendelsohn, M.H.

    1992-12-01T23:59:59.000Z

    The kinetics of the reduction of ferric chelate by ascorbic acid have been determined at a typical flue-gas scrubber-system operating temperature ({approximately}55{degrees}C). The ascorbic acid reaction has the same reduction rate expression as the reduction by bisulfite ions, namely, first order with respect to the concentrations of both Fe(III)*EDTA and monoionic species of ascorbic acid. The reaction rate isnegative first order with respect to Fe(II)*EDTA concentration. In the pH range of 6--8, reduction of the hydrolyzed form of the metal chelate compound was negligible. The rate constant for the ascorbic acid reduction reaction is almost 400 times larger than that for the bisulfite reduction reaction under the same reaction conditions. There was no contribution associated with the nonionized form of ascorbic acid.

  10. Kinetics of Fe(III)*EDTA reduction by ascorbic acid

    SciTech Connect (OSTI)

    Li, W.; Harkness, J.B.L.; Mendelsohn, M.H.

    1992-01-01T23:59:59.000Z

    The kinetics of the reduction of ferric chelate by ascorbic acid have been determined at a typical flue-gas scrubber-system operating temperature ([approximately]55[degrees]C). The ascorbic acid reaction has the same reduction rate expression as the reduction by bisulfite ions, namely, first order with respect to the concentrations of both Fe(III)*EDTA and monoionic species of ascorbic acid. The reaction rate isnegative first order with respect to Fe(II)*EDTA concentration. In the pH range of 6--8, reduction of the hydrolyzed form of the metal chelate compound was negligible. The rate constant for the ascorbic acid reduction reaction is almost 400 times larger than that for the bisulfite reduction reaction under the same reaction conditions. There was no contribution associated with the nonionized form of ascorbic acid.

  11. Transport Phenomena in Polymer Electrolyte Membranes II. Binary Friction Membrane Model

    E-Print Network [OSTI]

    Struchtrup, Henning

    is derived to represent conditions found in alternating current ac impedance conductivity measurements the conditions of ac impedance conductivity measurements. Using em- pirically fitted transport parameters dynamic models required for fundamental simulation of in situ processes that are difficult to ob- serve

  12. 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 DataDepartment of Energy Your Density Isn't YourTransport inEnergy0.pdf Flash2010-60.pdf2 DOE March, 20152LLC andActivitiesDepartment

  13. 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.

  14. Systematic Breakdown of Amontons' Law of Friction for an Elastic Object Locally Obeying Amontons' Law

    E-Print Network [OSTI]

    Michio Otsuki; Hiroshi Matsukawa

    2013-04-04T23:59:59.000Z

    In many sliding systems consisting of solid object on a solid substrate under dry condition, the friction force does not depend on the apparent contact area and is proportional to the loading force. This behaviour is called Amontons' law and indicates that the friction coefficient, or the ratio of the friction force to the loading force, is constant. Here, however, using numerical and analytical methods, we show that Amontons' law breaks down systematically under certain conditions for an elastic object experiencing a friction force that locally obeys Amontons' law. The macroscopic static friction coefficient, which corresponds to the onset of bulk sliding of the object, decreases as pressure or system length increases. This decrease results from precursor slips before the onset of bulk sliding, and is consistent with the results of certain previous experiments. The mechanisms for these behaviours are clarified. These results will provide new insight into controlling friction.

  15. 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.

  16. asbestos-free friction lining: Topics by E-print Network

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

    along the separation coordinate and thus to unambiguously disentangle the effects of free-energy and local friction on the separation kinetics. For tightly coordinated water...

  17. Non-equilibrium Statistical Approach to Friction Models

    E-Print Network [OSTI]

    Shoichi Ichinose

    2015-05-18T23:59:59.000Z

    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.

  18. 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.

  19. 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.

  20. Evaluation of friction loss in flexible and galvanized duct

    E-Print Network [OSTI]

    Zimmermann, Carlos Michael Alberto

    1985-01-01T23:59:59.000Z

    for Friction Loss in Straight Runs of Duct (a'Ipha=0. 10). 21 Ill Static Pressure Data Converted to Equivalent Lengths. 23 IV Duncan's Multiple Range Test of Variability for Equivalent Lengths of 90 Degree Elbows (al pha=0. IO). 26 V Student t Test... in the system was controlled by a discharge damper and metered with an orifice meter. The static pressure data was collected by the use of a pizometer ring located at the exhaust portion of the test apparatus where the flexible duct was connected...

  1. 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.

  2. Micro-origin of Macro-strength: Friction

    E-Print Network [OSTI]

    Alex X. Jerves; José E. Andrade

    2013-02-05T23:59:59.000Z

    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.

  3. 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.

  4. DNAPL source control by reductive dechlorination with iron-based degradative solidification/stabilization 

    E-Print Network [OSTI]

    Do, Si Hyun

    2009-05-15T23:59:59.000Z

    Iron-based degradative solidification/stabilization (Fe(II)-DS/S) is a treatment method that could be economically applied to smaller DNAPL-contaminated sites and to those sites with impermeable soils. Reductive dechlorination is achieved...

  5. 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...

  6. 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

  7. On the rate-independent limit of systems with dry friction and small viscosity

    E-Print Network [OSTI]

    Mielke, Alexander

    On the rate-independent limit of systems with dry friction and small viscosity Messoud A. Efendiev of this work is to present a model which is able to account for viscous as well as for dry-friction effects slow time scale, in which viscous transitions are seen as instantaneous jumps. However, effects of dry

  8. Dense granular flows: two-particle argument accounts for friction-like constitutive law with threshold

    E-Print Network [OSTI]

    Boyer, Edmond

    Dense granular flows: two-particle argument accounts for friction-like constitutive law that exhibits a flow threshold expressed as a finite effective friction at flow onset. The value 83.10.Gr 83.60.La I. INTRODUCTION Dense flows of dry granular materials and granular pastes is still

  9. Anomalous density dependence of static friction in sand Viktor K. Horvath,1

    E-Print Network [OSTI]

    Jánosi, Imre M.

    Anomalous density dependence of static friction in sand Viktor K. Horva´th,1 Imre M. Ja´nosi,2; revised manuscript received 26 April 1996 We measured experimentally the static friction force Fs on the surface of a glass rod immersed in dry sand. We observed that Fs is extremely sensitive to the closeness

  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. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

    : friction stir welding; modeling; theory; velocity field; peak temperature; torque; hardness; aluminum welding (FSW), well-tested analytical models of materials flow, peak temperatures, torque, and weldActa Materialia 59 (2011) 2020-2028 1 Back of the envelope calculations in friction stir welding

  17. 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

  18. Measurement of friction noise versus contact area of rough surfaces weakly loaded

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    contact area. The friction-induced vibration is generated by the sliding of two rough surfaces. The normal load is low leading to a weak contact. The normal load and the sliding velocity are maintained constant], friction noises can be classified in two types depending on the contact pressure. When the contact pressure

  19. 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 for friction and plastic deformation and pressure solution creep to be efficient on the same timescale. During vanishing, eventually reaching the stable sliding regime. Concomitantly, the contact interface, observed

  20. 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, salt, an analogue for natural8 faults, allows for frictional processes plastic deformation and pressure sliding regime. Concomitantly, the contact13 interface, observed under the microscope, develops a striated

  1. ccsd-00000893(version1):28Nov2003 Sliding Friction at a Rubber/Brush Interface

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ccsd-00000893(version1):28Nov2003 Sliding Friction at a Rubber/Brush Interface Lionel Bureau) rubber network sliding, at low velocity, on a substrate on which PDMS chains are end-tethered. We thus the friction, depending on their areal density. Casoli et al.9 further studied the behaviour of such rubber

  2. Visualizing stickslip: experimental observations of processes governing the nucleation of frictional sliding

    E-Print Network [OSTI]

    Fineberg, Jay

    Charles-Augustin de Coulomb repeated the experiments adding the first formulation of dynamic friction laws of frictional sliding This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2009 J. Phys. D: Appl. Phys. 42 214016 (http://iopscience.iop.org/0022

  3. Resource Letter: FMMLS-1: Friction at macroscopic and microscopic length scales

    E-Print Network [OSTI]

    Krim, Jacqueline

    as their weights are equal. A third law, at- tributed to French physicist Charles Augustin Coulomb bet- ter known is independent of velocity for ordinary sliding speeds. Amontons' and Coulomb's laws have far outlived a variety of friction. Books, reviews, and journal articles are cited for the following topics: History of friction

  4. ORIGINAL PAPER 1D Model of Precursors to Frictional Stick-Slip Motion Allowing

    E-Print Network [OSTI]

    Scheibert, Julien

    ], using a 1D spring-block model with a simple Amontons-Coulomb (AC) friction law, showed that the length November 2011 Ó Springer Science+Business Media, LLC 2011 Abstract In this article, we studythe dynamic], using a one-dimen- sional (1D) spring-block model with a complex time- dependent friction law, produced

  5. Numerical Study on Transverse Friction of a Slender Rod Contacting the Seabed 

    E-Print Network [OSTI]

    Lu, Hang

    2012-10-19T23:59:59.000Z

    support force and longitudinal (along the direction of the rod) friction from soils of the seabed while the transverse (in the direction transverse to the slender rod) friction between the rod and the seabed soils is not considered. In this study, we...

  6. Homogenization in non linear dynamics due to frictional contact Peillex G. a

    E-Print Network [OSTI]

    Boyer, Edmond

    homogenization process and its influence on the behavior of a composite under non linear dynamic loading due homogenization process, coupled with an homogenization of the frictional contact, enables replacing the entire in the heterogeneous models are identified by using the relocalization process and a frictional contact dynamic

  7. 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.

  8. A PERSPECTIVE ON THE NUMERICAL AND EXPERIMENTAL CHARACTERISTICS OF MULTI-MODE DRY-FRICTION WHIP AND WHIRL

    E-Print Network [OSTI]

    Wilkes, Jason C.

    2010-01-16T23:59:59.000Z

    interactions. The interaction at the rub surface is modeled using a nonlinear Hunt and Crossley contact model with coulomb friction. Dry-friction simulations are performed for specific test cases and compared against experimental data to determine the validity...

  9. 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.

  10. 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.

  11. Friction control using ultrasonic oscillation for rolling-element linear-motion guide

    SciTech Connect (OSTI)

    Oiwa, Takaaki [Shizuoka University, 3-5-1 Hamamatsu, Shizuoka 432-8651 (Japan)

    2006-01-15T23:59:59.000Z

    This article reports a friction-control method for rolling-element linear-motion guides used for precision positioning. In general, static friction greater than dynamic friction generates stick-slip motion and diminishes the positioning accuracy. Two ultrasonic actuators excite both the rail and the carriage of the guide to give relative displacements to bearing surfaces. In order to effectively propagate the vibration over the entire rail without damping, the actuator drives at that frequency with a half wavelength corresponding to the distances between the rail mounting bolts. This also minimizes undesirable vibration of the machine structure. Moreover, the bearing surfaces of the carriage are resonated by a second ultrasonic actuator. The experiments using a force sensor showed that the static and dynamic friction forces were reduced by approximately 25% at any place on the 600-mm-long rail. Moreover, excitation only at very low velocity decreased the static friction peak.

  12. 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

    2005-04-01T23:59:59.000Z

    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) and provided information to be used to assess CO{sub 2} sequestration opportunities in the PCOR Partnership region. Task 2 efforts also included preparation of a draft topical report entitled ''Deployment Issues Related to Geologic CO{sub 2} Sequestration in the PCOR Partnership Region'', which is nearing completion. Task 3 (Public Outreach) focused on developing an informational video about CO{sub 2} sequestration. The video will be completed and aired on Prairie Public Television in the next quarter. 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. The addition of the Canadian province of Alberta to the PCOR Partnership region expanded the decision support system (DSS) geographic information system database. Task 5 screened and qualitatively assessed sequestration options. Task 5 activities also continue to be useful in structuring data collection and other activities in Tasks 2, 3, and 5.

  13. 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.

  14. 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

  15. 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

  16. Incorporating friction and collective shear moves into a lattice gas Alex Dickson, Alice Nasto, and Aaron R. Dinner

    E-Print Network [OSTI]

    Dinner, Aaron

    Incorporating friction and collective shear moves into a lattice gas Alex Dickson, Alice Nasto a lattice-gas model that has been extended to include collective shear moves and friction interactions of the lattice with respect to one another, as opposed to biasing the individual movements of particles. Friction

  17. 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...Õ,,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

  18. 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

  19. Brownian motion with dry friction: Fokker-Planck Hugo Touchette, Erik Van der Straeten, and Wolfram Just

    E-Print Network [OSTI]

    Just, Wolfram

    Brownian motion with dry friction: Fokker-Planck approach Hugo Touchette, Erik Van der Straeten Gennes, in which there is a solid-solid or dry friction force acting on a Brownian particle in addition-dependent Fokker-Planck equation. Exact results are found for the case where only dry friction acts on the particle

  20. Tribology Letters Vol. 10, No. 1-2, 2001 15 Dry friction between flat surfaces: multistable elasticity vs.

    E-Print Network [OSTI]

    Mueser, Martin

    Tribology Letters Vol. 10, No. 1-2, 2001 15 Dry friction between flat surfaces: multistable-Universität, 55099 Mainz, Germany E-mail: martin.mueser@uni-mainz.de A generic model for frictional forces between to finite pinning (static friction) forces are analyzed by varying the geometry, the interfacial interaction

  1. On large deviation properties of Brownian motion with dry friction Yaming Chen 1, # and Wolfram Just 1, +

    E-Print Network [OSTI]

    Just, Wolfram

    On large deviation properties of Brownian motion with dry friction Yaming Chen 1, # and Wolfram with dry friction, including quantitative measures to characterize deviation from Gaussian behaviour to dry friction as an illustrative example where explicit expressions for the distribution of functionals

  2. Texture-induced modulations of friction force: the fingerprint effect E. Wandersman, R. Candelier, G. Debregeas, and A. Prevost

    E-Print Network [OSTI]

    , CNRS FRE 3231, 24 rue Lhomond, 75005 Paris, France (Dated: July 13, 2011) Dry solid friction is oftenTexture-induced modulations of friction force: the fingerprint effect E. Wandersman, R. Candelier characteristics of the substrate. The model's main ingredient is the non-linearity of the friction law. Since

  3. Effect of friction on the force distribution in sheared granular materials A. Singh, V. Magnanimo & S. Luding

    E-Print Network [OSTI]

    Luding, Stefan

    averaging in the steady state. Simulations of dry particles with and without friction have been validatedEffect of friction on the force distribution in sheared granular materials A. Singh, V. Magnanimo of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. The effect of friction on the quasi

  4. Evaluation of the real contact area in three-body dry friction by micro-thermal analysis

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Evaluation of the real contact area in three-body dry friction by micro- thermal analysis Philippe the real AFM maps. Keywords: Scanning thermal microscopy; Friction; Third body; Greenwood­Williamson approach 1. Introduction Many tribological properties--such as friction and wear--greatly depend on the so

  5. 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

  6. APOLLO II

    SciTech Connect (OSTI)

    Sanchez, R.; Mondot, J.; Stankovski, Z.; Cossic, A.; Zmijarevic, I.

    1988-11-01T23:59:59.000Z

    APOLLO II is a new, multigroup transport code under development at the Commissariat a l'Energie Atomique. The code has a modular structure and uses sophisticated software for data structuralization, dynamic memory management, data storage, and user macrolanguage. This paper gives an overview of the main methods used in the code for (a) multidimensional collision probability calculations, (b) leakage calculations, and (c) homogenization procedures. Numerical examples are given to demonstrate the potential of the modular structure of the code and the novel multilevel flat-flux representation used in the calculation of the collision probabilities.

  7. II f

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling CorpNewCF INDUSTRIES,L? .-I I ,Is II:c* -W.f - f

  8. Ii1

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling CorpNewCF INDUSTRIES,L? .-I I ,Is II:c*1r' (-r

  9. Frictionally induced ignition processes in drop and skid tests

    SciTech Connect (OSTI)

    Dickson, Peter [Los Alamos National Laboratory; Parker, Gary [Los Alamos National Laboratory; Novak, Alan [Los Alamos National Laboratory

    2010-01-01T23:59:59.000Z

    The standard LANL/Pantex drop and skid tests rely on subjective assessment of reaction violence to quantify the response of the charge, and completely miss nonpropagating hot-spot ignition sites. Additionally, large variations in test results have been observed, which we propose is due to a misunderstanding of the basic physical processes that lead to threshold ignition in these tests. The tests have been redesigned to provide control of these mechanisms and to permit direct observation of hot spots at the impact site, allowing us to follow the progression of the outcome as the drop height and ignition source density are varied. The results confirm that frictional interactions between high-melting-point solids are the dominant ignition mechanism, not just at the threshold, but in fact at all realistic drop heights.

  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 position detection and control for friction stir systems

    SciTech Connect (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.

  12. The Impact of Organic Friction Modifiers on Engine Oil Tribofilms

    E-Print Network [OSTI]

    Ratoi, Monica; Alghawel, Husam; Suen, Yat Fan; Nelson, Kenneth

    2013-01-01T23:59:59.000Z

    Organic friction modifiers (OFMs) are important additives in the lubrication of machines and especially of car engines where performance improvements are constantly sought-after. Together with zinc dialkyldithiophosphates (ZDDPs) antiwear additives, OFMs have a predominant impact on the tribological behaviour of the lubricant. In the current study, the influence of OFMs on the generation, tribological properties and chemistry of ZDDP tribofilms has been investigated by combining tribological experiments (MTM) with in-situ film thickness measurements through optical interference imaging (SLIM), Alicona profilometry and X-ray photoelectron spectroscopy. OFMs and antiwear additives have been found to competitively react/adsorb on the rubbing ferrous substrates in a tribological contact. The formation and removal (through wear) of tribofilms are dynamic processes which result from the simultaneous interaction of these two additives with the surface of the wear track. By carefully selecting the chemistry of OFMs, ...

  13. 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.

  14. Identification and characterization of agent for reductive dechlorination in mixtures of ferrous iron and Portland cement 

    E-Print Network [OSTI]

    Ko, Sae Bom

    2001-01-01T23:59:59.000Z

    Degradative Solidification/Stabilization (DS/S) is a modification of conventional S/S in which organic pollutants are destroyed while inorganic pollutants are immobilized. Fe(II) is used in Fe(II)-based DS/S as a reductant to degrade organic...

  15. 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

  16. 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.

  17. 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

  18. 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...

  19. Investigation of wall friction in noncircular ducts with a rough liner

    E-Print Network [OSTI]

    Tyler, John Charles

    1959-01-01T23:59:59.000Z

    section Density Viscosity Dimensions L5/Q L/Q m/L& m/LQ 1. The friction factors, Reynolds numbers, and. abso- lute roughnesses for fluid flow in ducts having a glass fiber liner have been calculated and plotted in the form of characteristic... distributed, it is essential that the wall friction phenomena associated with the particular duct design be understood. When fluid is passed through a duct, a static pressure drop occurs due to the friction forces which act between the fluid. particles...

  20. Forest Fuels ReductionForest Fuels Reduction Department of

    E-Print Network [OSTI]

    Bolding, M. Chad

    the initial fuels reduction treatments leave the site with regard to long-term forest vegetation and soil are the productivity and cost rates for alternative choices of equipment for mechanical fuels reduction; what reduction operations for existing markets and new markets? (eg. biomass energy) Research Rationale

  1. 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

  2. Duhem Models for Hysteresis in Sliding and Presliding Friction* JinHyoung Oh, Ashwani K. Padthe, Dennis S. Bernstein, Demosthenis D. Rizos, and Spilios D. Fassois

    E-Print Network [OSTI]

    Sontag, Eduardo

    , namely, Coulomb friction, is discontinuous. Discontinuous dry friction models are studied in [15]. Some is challenging since some models involve nonsmooth dynamics. For example, the most widely used dry friction modelDuhem Models for Hysteresis in Sliding and Presliding Friction* JinHyoung Oh, Ashwani K. Padthe

  3. INITIAL DEVELOPMENT OF A VARIABLE-FRICTION FLOOR SURFACE Guillaume Millet, Martin J.-D. Otis, Gary Chaw, Jeremy R. Cooperstock

    E-Print Network [OSTI]

    Cooperstock, Jeremy R.

    ). An- other is by changing dry friction into lubricated friction, that is, placing a lubricant quantified with Coulomb's model; examples of coefficients of static friction are 0.04 for PTFE/PTFE contactINITIAL DEVELOPMENT OF A VARIABLE-FRICTION FLOOR SURFACE Guillaume Millet, Martin J.-D. Otis, Gary

  4. 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

    fricci´on para flujos turbulentos en tuber´ias m´as efectiva (es posible obtener reducciones de hasta un factor de 8 en los coeficientes de fricci´on en segmentos de tuber´ias rectas). Desde el punto de vista aplicaciones sigue en proceso, p.ej., en sistemas centrales de calefacci´on y aire acondicionado, sistemas hidr

  5. 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...

  6. 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 ...

  7. Internal friction and absence of dilatancy of packings of frictionless polygons

    E-Print Network [OSTI]

    Radjai, Franck

    By means of numerical simulations, we show that assemblies of frictionless rigid pentagons in slow shear flow possess an internal friction coefficient (equal to 0.183 ± 0.008 with our choice of moderately polydisperse ...

  8. Exact solutions to the compressible Navier-Stokes equations with the Coriolis and friction terms

    E-Print Network [OSTI]

    Korshunova, Anastasya

    2008-01-01T23:59:59.000Z

    We consider special solution to the 3D compressible Navier-Stokes system with and without the Coriolis force and dry friction and find the respective initial data implying a finite time gradient catastrophe.

  9. Kinetic and Friction Head Loss Impacts on Horizontal Water Supply and Aquifer Storage and Recovery Wells 

    E-Print Network [OSTI]

    Blumenthal, Benjamin

    2014-12-02T23:59:59.000Z

    well construction or intra-wellbore head loss. Currently no analytical groundwater model rigorously accounts for intra-wellbore kinetic and friction head loss. We have developed a semi-analytical, intra-wellbore head loss model dynamically linked...

  10. Rest-to-Rest Motion of an Experimental Flexible Structure subject to Friction: Linear Programming

    E-Print Network [OSTI]

    Singh, Tarunraj

    and robot arm position- ing. Velocity control is also relevant in machine tool, disk drive and robot arm of controllers in this area include high precision overhead robot arms subject to friction at the joints, high

  11. 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 ...

  12. Transition from static to kinetic friction: Insights from a 2D model

    E-Print Network [OSTI]

    Trømborg, Jørgen; Amundsen, David Skålid; Thøgersen, Kjetil; Malthe-Sørenssen, Anders

    2013-01-01T23:59:59.000Z

    We describe a 2D spring-block model for the transition from static to kinetic friction at an elastic slider/rigid substrate interface obeying a minimalistic friction law (Amontons-Coulomb). By using realistic boundary conditions, a number of previously unexplained experimental results on precursory micro-slip fronts are successfully reproduced. From the analysis of the interfacial stresses, we derive a prediction for the evolution of the precursor length as a function of the applied loads, as well as an approximate relationship between microscopic and macroscopic friction coefficients. We show that the stress build-up due to both elastic loading and micro-slip-related relaxations depend only weakly on the underlying shear crack propagation dynamics. Conversely, crack speed depends strongly on both the instantaneous stresses and the friction coefficients, through a non-trivial scaling parameter.

  13. 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) ...

  14. 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 ...

  15. Turbulent heat transfer and friction in a square channel with discrete rib turbulators

    E-Print Network [OSTI]

    McMillin, Robert Dale

    1989-01-01T23:59:59.000Z

    TURBULENT HEAT TRANSFER AND FRICTION IN A SQUARE CHANNEL WITH DISCRETE RIB TURBULATORS A Thesis by ROBERT DALE iXIGMILLIN Subniitted to the Office of Graduate Studies of Texas AK. M L niversrty in partial fulfillment of the requirements... for the degree of MASTER OF SGIE IGE Deceinber 1989 Major Subject' Mechanical Engineering TURBULENT HEAT TRANSFER AND FRICTION IN A SQUARE CHANNEL WITH DISCRETE RIB TURBULATORS A Thesrs by ROBERT DALE MCMILLI'V Approverl as to style and content...

  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. The measurement of contact areas and temperature during frictional sliding of Tennessee sandstone 

    E-Print Network [OSTI]

    Teufel, Lawrence William

    1976-01-01T23:59:59.000Z

    THE MEASUREMENT OF CONTACT AREAS AND TEMPERATURE DURING FRICTIONAL SLIDING OF TENNESSEE SANDSTONE A Thesis by LAWRENCE WILLIAM TEUFEL Submit';ed to the Graduate College of Texas ASM University in partial fulfillment of the requirements... for the degree of MASTERS OF SCIENCE August 1976 Major Subiect: Geology THE MEASUREMENT OF CONTACT AREAS AND TEMPERATURES DURING FRICTIONAL SLIDING OF TENNESSEE SANDSTONE A Thesis by LAWRENCE WILLIAM TEUFEL Approved as to sty1e and content by: Cha rma...

  18. Frictional characteristics of serpentinite from the Motagua fault zone in Guatemala: an experimental study 

    E-Print Network [OSTI]

    Dengo, Carlos Arturo

    1978-01-01T23:59:59.000Z

    of the requirement for the degree of MASTER OF SCIENCE December 1978 Mad or Subjec' . " Geology FRICTIONAL CHARACTERISTIC OF SERPENTINITF. FRON THE I", OTAGUA FAULT ZONE Ili GUATENALA: AN EXPERIMENTAL STUDY A Thesis by CARLOS ARTURO DFNGO App", oved... strike-slip, seismogenic faults warrants a systematic i nvesti ga tion to determine ho v it". frictional characteristics may afreet slip along the fault. Five locations aiong the fault zone were sampled to investigate the sliding !rode as a function...

  19. Frictional properties between fine grained limestone, dolomite and sandstone along precut surfaces 

    E-Print Network [OSTI]

    Iwasaki, Takeshi

    1970-01-01T23:59:59.000Z

    characteristic parallel lines upon its surface in the direction of slid- ing. If the two materials are the same, both surfaces flow equally, and mutual adhesion and welding occur at the points of contact. In the latter case, frictional work is required... FRICTIONAL PROPERTIES BETNEEN FINE GRAINED I, IMESTONE, DOLOMI"'E AND SANDSTONE ALONG PRECUT SURFACFS A Thesis TAKESHI INASAKI Submitted to the Graduate College of Texas MN University in partial fulfillment of the requirements for the degree...

  20. 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.

  1. Frictional properties between fine grained limestone, dolomite and sandstone along precut surfaces

    E-Print Network [OSTI]

    Iwasaki, Takeshi

    1970-01-01T23:59:59.000Z

    shear surface; w, wet surface; c, clean surface. Table 1. Coefficients of friction of rocks and Minerals (cited from Jaeger and Cook, 1969). EXPERIMENTAL PROCEDURE Triaxial compression experiments were conducted on dry, copper-jacketed samples in a...) and Handin (1969) suggested that it reflected the brittle-ductile transition of the tested rocks. The cohesive shear strength is zero across a precut surface, so in the brittle state Coulomb's cri- terion predicts that coefficient of sliding friction...

  2. Bifurcation for Non-smooth Dynamical Systems via Reduction Methods

    E-Print Network [OSTI]

    Lubich, Christian

    non-smooth effects are due to dry friction or impacts in mechanics, switches in electrical systems investigations had been stimulated by experiments exploring phenomena re- lated to dry friction or impacts, transition from sticking to sliding due to friction and sudden loss of stability as typically observed

  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. 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.

  5. Vehicle Technologies Office: National Idling Reduction Network...

    Office of Environmental Management (EM)

    Idling Reduction Network News Archives Vehicle Technologies Office: National Idling Reduction Network News Archives The National Idling Reduction Network brings together trucking...

  6. 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.

  7. Dose Reduction Techniques

    SciTech Connect (OSTI)

    WAGGONER, L.O.

    2000-05-16T23:59:59.000Z

    As radiation safety specialists, one of the things we are required to do is evaluate tools, equipment, materials and work practices and decide whether the use of these products or work practices will reduce radiation dose or risk to the environment. There is a tendency for many workers that work with radioactive material to accomplish radiological work the same way they have always done it rather than look for new technology or change their work practices. New technology is being developed all the time that can make radiological work easier and result in less radiation dose to the worker or reduce the possibility that contamination will be spread to the environment. As we discuss the various tools and techniques that reduce radiation dose, keep in mind that the radiological controls should be reasonable. We can not always get the dose to zero, so we must try to accomplish the work efficiently and cost-effectively. There are times we may have to accept there is only so much you can do. The goal is to do the smart things that protect the worker but do not hinder him while the task is being accomplished. In addition, we should not demand that large amounts of money be spent for equipment that has marginal value in order to save a few millirem. We have broken the handout into sections that should simplify the presentation. Time, distance, shielding, and source reduction are methods used to reduce dose and are covered in Part I on work execution. We then look at operational considerations, radiological design parameters, and discuss the characteristics of personnel who deal with ALARA. This handout should give you an overview of what it takes to have an effective dose reduction program.

  8. 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.

  9. 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.

  10. Abiotic Reductive Immobilization of U(VI) by Biogenic Mackinawite

    SciTech Connect (OSTI)

    Veeramani, Harish; Scheinost, Andreas; Monsegue, Niven; Qafoku, Nikolla; Kukkadapu, Ravi K.; Newville, Mathew; Lanzirotti, Anthony; Pruden, Amy; Murayama, Mitsuhiro; Hochella, Michael F.

    2013-03-01T23:59:59.000Z

    During subsurface bioremediation of uranium-contaminated sites, indigenous metal and sulfate-reducing bacteria may utilize a variety of electron acceptors, including ferric iron and sulfate that could lead to the formation of various biogenic minerals in-situ. Sulfides, as well as structural and adsorbed Fe(II) associated with biogenic Fe(II)-sulfide phases, can potentially catalyze abiotic U6+ reduction via direct electron transfer processes. In the present work, the propensity of biogenic mackinawite (Fe1+xS, x = 0 to 0.11) to reduce U6+ abiotically was investigated. The biogenic mackinawite produced by Shewanella putrefaciens strain CN32 was characterized by employing a suite of analytical techniques including TEM, SEM, XAS and Mössbauer analyses. Nanoscale and bulk analyses (microscopic and spectroscopic techniques, respectively) of biogenic mackinawite after exposure to U6+ indicate the formation of nanoparticulate UO2. This study suggests the relevance of Fe(II) and sulfide bearing biogenic minerals in mediating abiotic U6+ reduction, an alternative pathway in addition to direct enzymatic U6+ reduction.

  11. 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...

  12. 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...

  13. 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...

  14. Waste Characterization, Reduction, and Repackaging Facility ...

    Office of Environmental Management (EM)

    Waste Characterization, Reduction, and Repackaging Facility (WCRRF) Waste Characterization Glovebox Operations Waste Characterization, Reduction, and Repackaging Facility (WCRRF)...

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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

    2014-10-03T23:59:59.000Z

    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.

  1. Dry Friction in the Frenkel-Kontorova-Tomlinson Model: Dynamical Properties

    E-Print Network [OSTI]

    Michael Weiss; Franz-Josef Elmer

    1997-04-14T23:59:59.000Z

    Wearless friction is investigated in a simple mechanical model called Frenkel-Kontorova-Tomlinson model. We have introduced this model in [Phys. Rev. B, Vol. 53, 7539 (1996)] where the static friction has already been considered. Here the model is treated for constant sliding speed. The kinetic friction is calculated numerically as well as analytically. As a function of the sliding velocity it shows many structures which can be understood by varies kinds of phonon resonances (normal, superharmonic and parametric) caused by the so-called "washboard wave". For increasing interaction strength the regular motion becomes chaotic (fluid-sliding state). The fluid sliding state is mainly determined by the density of decay channels of m washboard waves into n phonons. We also find strong bistabilities and coherent motions with superimposed dark envelope solitons which interact nondestructively.

  2. NUMERICAL STUDIES OF THE FRICTION FORCE FOR THE RHIC ELECTRON COOLER.

    SciTech Connect (OSTI)

    FEDOTOV,A.V.; BEN-ZVI,I.; LITVINENKO, V.

    2005-05-16T23:59:59.000Z

    Accurate calculation of electron cooling times requires an accurate description of the dynamical friction force. The proposed RHIC cooler will require {approx}55 MeV electrons, which must be obtained from an RF linac, leading to very high transverse electron temperatures. A strong solenoid will be used to magnetize the electrons and suppress the transverse temperature, but the achievable magnetized cooling logarithm will not be large. In this paper, we explore the magnetized friction force for parameters of the RHIC cooler, using the VORPAL code [l]. VORPAL can simulate dynamical friction and diffusion coefficients directly from first principles [2]. Various aspects of the fiction force are addressed for the problem of high-energy electron cooling in the RHIC regime.

  3. Effects of heterogeneity and friction on the deformation and strength of rock

    SciTech Connect (OSTI)

    Nihei, K.T.; Myer, L.R.; Liu, Z.; Cook, N.G.W. [Lawrence Berkeley Lab., CA (United States); Kemeny, J.M. [Univ., of Arizona, Tucson, AZ (United States). Dept. of Mineralogy and Geological Engineering

    1994-03-01T23:59:59.000Z

    Experimental observations of the evolution of damage in rocks during compressive loading indicate that macroscopic failure occurs predominantly by extensile crack growth parallel or subparallel to the maximum principal stress. Extensile microcracks initiate at grain boundaries and open pores by a variety of micromechanical processes which may include grain bending, Brazilian type fracture and grain boundary sliding. Microstructural heterogeneity in grain size, strength and shape determines the magnitude of the local tensile stresses which produce extensile microcracking and the stability with which these microcracks coalesce to form macrocracks. Friction at grain boundaries and between the surfaces of microcracks reduces the strain energy available for extensile crack growth and increases the stability of microcrack growth. In clastic rocks, frictional forces may improve the conditions for extensile microcrack growth by constraining the amount of sliding and rotation of individual grains. Micromechanical models are used to investigate the effects of heterogeneity and friction on the deformation and strength of crystalline and clastic rocks.

  4. Ab-initio friction forces on the nanoscale: A DFT study of fcc Cu(111)

    E-Print Network [OSTI]

    Wolloch, Michael; Mohn, Peter; Redinger, Josef; Vernes, András

    2014-01-01T23:59:59.000Z

    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 ...

  5. 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).

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

    E-Print Network [OSTI]

    Lionel Bureau

    2007-07-13T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Johan S. Høye; Iver Brevik

    2011-06-04T23:59:59.000Z

    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.

  8. 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 QUARTZOSE SANDSTONE A Thesis by MICHAEL LLOYD BLACKWELL Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE May 1973 Ma)or Sub)ect: Geophysics THE INFLUENCE OF PORE FLUIDS ON THE FRICTIONAL PROPERTIES OF QUARTZOSE SANDSTONE A Thesis by MICHAEL LLOYD BLACKHELL Approved as to style and content by: (Chai of Committee) (Head of De rtment) (Member...

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

    E-Print Network [OSTI]

    Hossain, Quazi A

    1967-01-01T23:59:59.000Z

    the results of their experiments and suggested the "welding" theory of friction. According to this theory, when two surfaces in contact are at rest or at low speed of sliding "cold welding" is produced by the intense pressure in the region of contact.... At higher speeds it is assisted by a high temperature softening or melting of the metal. The frictional force is, in a large measure, the force required to shear these welded junctions. In 1952, Ming Feng (27) proposed a theory which partially...

  10. In-situ measurements of friction and bearing correlated with instrumented pile tests 

    E-Print Network [OSTI]

    Perdue, George William

    1970-01-01T23:59:59.000Z

    of Committee) (Head o Depar me (Member) (Hember) August 1970 ABSTBACT In-Situ measurements of Friction and Bearing Correlated with Instrumented Pile Tests (August 1 gy0 ) George M. Perclue, B. S. , Texas ABN University Superv1sed by: Dr. Harry l1.... Coyle This study involved a ser1es of f1eld tests conducted with a recently developed 1n-situ testing dev1ce. The in-situ test1ng device was used to measure values of skin friction and po1nt bearing taken during so11 sampl1ng operations. The test...

  11. 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.

  12. In-situ measurements of friction and bearing correlated with instrumented pile tests

    E-Print Network [OSTI]

    Perdue, George William

    1970-01-01T23:59:59.000Z

    values, in-situ measurements of tip-only tests, embedded tests, and the corresponding CT values, TABLE 4 SERIES I FRICTION DATA ? PILE I- Ir?MEDIATE STATIC LOAD TEST DEPTH FEET 12. 0 21. 5 30. 0 31. 0 32. 0 40. 5 41. 5 50. 0 60. 5 61. 5... Procedure 20 20 20 21 22 ANALYSIS OF TEST RESULTS General Instrumented Pile Test Data . In-Situ Friction Test Data In-Situ Bearing Test Data . Correlation with Soil Properties 27 27 28 30 41 42 COiNCLUSIOiNS A!ND P...

  13. Lyapunov Stability and Precise Control of the Frictional Dynamics of a Onc-Dimensional Particle Array

    SciTech Connect (OSTI)

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

    2006-01-01T23:59:59.000Z

    Using Lyapunov theory and numerical simulations, we analyze the local stability of an array of mechanically coupled particles whose frictional dynamics is described by the Frenkel-Kontorova model, and design feedback controls to precisely control the friction. We first establish the asymptotic stability of the system around the equilibrium positions of the particles.We then show how to construct efficient feedback control laws to achieve any predestined average velocity of the particle array, with no fluctuation, and irrespective of the detailed nature of the interparticle coupling. These rigorous results are supported in extensive numerical simulations, and are expected to be applicable to other related physical systems as well.

  14. 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

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

    E-Print Network [OSTI]

    Cambridge, University of

    in the context of welding difficult aluminium alloys. We now apply this scheme to the friction stir welding for the welding of 7075 aluminium alloy.15 The results of the analysis were presented in the form of maps and the consequences on the physical metallurgy of the steel. Introduction Friction stir welding (FSW) of aluminium

  16. 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...

  17. 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...

  18. NOx Reduction through Efficiency Gain 

    E-Print Network [OSTI]

    Benz, R.; Thompson, R.; Staedter, M.

    2007-01-01T23:59:59.000Z

    with a novel control design to deliver a comprehensive boiler controls retrofit that provides reductions in emissions as well as substantial cost savings. Combining mechanical engineering expertise with substantial experience in control engineering...

  19. 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...

  20. DYNAMIC FRICTION EXPERIMENTS AT THE ATLAS PULSED POWER C. L. Rousculp, J. E. Hammerberg, D. M. Oro, G. Rodriguez, P. M. Goodwin,

    E-Print Network [OSTI]

    Kurien, Susan

    DYNAMIC FRICTION EXPERIMENTS AT THE ATLAS PULSED POWER FACILITY C. L. Rousculp, J. E. Hammerberg, D contract DE-AC52-06NA25396 Abstract A Series of dynamic friction experiments has been conducted frictional forces occurring there. Other diagnostics included a single-point VISAR and line-ORVIS to measure

  1. Bull. Disas. Prey. Res. Inst., Kyoto Univ., Vol. 45, Part 4, No. 393, March, 1996 A Study on the Apparent Friction Angle Mobilized

    E-Print Network [OSTI]

    Takada, Shoji

    on the Apparent Friction Angle Mobilized during the Undrained Loading in Long Run-out Landslides ByJong-hak LEEand friction angles during motion in comparison with the usual values of internal friction angle of soils stress in dry soils, normal stress was rapidly increased while shearing speed was maintained. In some

  2. Stopping dynamics of sliding and spinning bodies on a at surface with dry friction. P.O. Fedichev and O.B. Fedichev

    E-Print Network [OSTI]

    Stopping dynamics of sliding and spinning bodies on a #29;at surface with dry friction. P both for the total time of motion and the distance traveled. Dry friction is widespread both in Nature questions. Dry friction as a physical phenomenon has long time became a textbook issue, see e.g. [1]. Modern

  3. J. Phys. I Ftance 7 (1997) 1391-1416 NOVEMBER1997, PAGE1391 Dry Friction as an Elasto-Plastic Response

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1997-01-01T23:59:59.000Z

    . Unlike the well known Amontons-Coulomb laws of dry friction, the recent precise experimental studiesJ. Phys. I Ftance 7 (1997) 1391-1416 NOVEMBER1997, PAGE1391 Dry Friction as an Elasto of Greenwood et at. [2] has niade clear that the niost salient feature of dry friction naniely the fact

  4. 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.

  5. 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

  6. 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.

  7. Friction factor for turbulent flow in rough pipes from Heisenberg's closure hypothesis

    E-Print Network [OSTI]

    Esteban Calzetta

    2009-04-17T23:59:59.000Z

    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.

  8. 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 and with an independent measurement of the angle calibration. This nondestructive calibration may be performed with any

  9. 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

  10. 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

  11. 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.

  12. Numerical study of friction-induced instability and acoustic radiation -Effect of ramp loading on the

    E-Print Network [OSTI]

    Boyer, Edmond

    is conducted for two cases of loadings and initial conditions: a static load near the associated sliding harmonic components in the velocity spectrum. Finally, the sound pressure convergence study shows that only a frictional interface [1]. During the braking process of a disc brake system, a hydraulic pressure is applied

  13. Transition from static to kinetic friction: Insights from a 2D model J. Trmborg,1

    E-Print Network [OSTI]

    Boyer, Edmond

    a satisfactory pic- ture of the steady sliding regime of such interfaces has been developed during the last sliding occurs only after shear crack-like micro-slip fronts have spanned the entire contact interface point in side-driven systems [11, 14, 16, 18] or by a friction-induced pressure asym- metry in top

  14. Transition from static to kinetic friction: insights from a 2D model J. Trmborg,1

    E-Print Network [OSTI]

    ] and nanomechanics [4]. Whereas a satisfactory pic- ture of the steady sliding regime of such interfaces has been shown that macro- scopic sliding occurs only after shear crack-like micro-slip fronts have spanned near the loading point in side-driven systems [10, 13, 15, 17] or by a friction-induced pressure asym

  15. Scanning Force Microscopy Studies on Molecular Packing and Friction Anisotropy in Thin Films of

    E-Print Network [OSTI]

    Kenis, Paul J. A.

    Scanning Force Microscopy Studies on Molecular Packing and Friction Anisotropy in Thin Films in bulk, was studied using differential scanning calorimetry, optical microscopy, magic angle solid were investigated at the molecular level by a combination of multimode scanning force microscopy (SFM

  16. The Effects of Molecular Weight and Temperature on the Kinetic Friction of Silicone Rubbers

    E-Print Network [OSTI]

    Chaudhury, Manoj K.

    The Effects of Molecular Weight and Temperature on the Kinetic Friction of Silicone Rubbers rubber products were performed for the sole purpose of tabulating properties for consumers with the purpose of understanding the physics of rubber sliding. Quantita- tive physical analysis began

  17. SURFACE PRESSURE AND SHEAR STRESS FIELDS WITHIN A FRICTIONAL CONTACT ON RUBBER

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    SURFACE PRESSURE AND SHEAR STRESS FIELDS WITHIN A FRICTIONAL CONTACT ON RUBBER Danh Toan Nguyen1 lens and a rubber (poly(dimethylsiloxane)) substrate. Experimental results show that high lateral of the displacement field requires that finite strains and non linear response of the rubber substrate are taken

  18. 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

  19. 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

  20. 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