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Silicon carbide (SiC) MOSFETs are known for their superior performance compared to traditional silicon devices, making them well-suited for a wide range of applications in power electronics. However, there is a lack of long-term reliability studies for SiC MOSFETs under real-world operating conditions. This article introduces an innovative inverter-like accelerated test (IAT) and compares it with the standard power cycling test (PCT) to thoroughly assess the degradation mechanisms and reliability of SiC MOSFETs. The IAT is designed to replicate the operational conditions of an inverter, providing a more realistic evaluation of the long-term performance of the SiC MOSFET. There are some differences in the principles of these two accelerated tests (ATs). The paper provides detailed insights into these differences and the methodologies used, including the test bench design and junction temperature estimation, and presents the experimental results. The findings highlight significant differences in the degradation behavior observed under IAT and PCT conditions and the lifetime evaluation, underscoring the necessity for realistic testing protocols to ensure reliable lifetime predictions for SiC MOSFETs in practical applications.

Controlling and monitoring the processing parameters during epoxy manufacturing is a challenging task and their variation impacts the curing process of the polymer and its final quality. To address this issue, destructive testing is typically performed for quality control and material characterization, which involves expensive lab-type equipment and instrument-specific sample preparation. Moreover, this type of testing cannot be taken in-field to perform an in-situ evaluation. This work presents a method to non-destructively evaluate the curing kinetics and viscoelastic properties of epoxy resin in real time due to variations in stoichiometry combining ultrasonics and Fourier Transform Infrared Spectroscopy. Samples with a different amine-to-epoxy ratio were manufactured and tested. Thermogravimetric analysis revealed that deviations from the recommended ratio promoted thermal degradation. Furthermore, changes in longitudinal sound speed were detected during the resin’s curing process, resulting from variations in the polymer’s chemical structure, and were correlated to the cure kinetics. The sound speeds of three baseline samples were determined during the curing process with an absolute error of ~0.13 % while changing the amine content by ±40 % caused alterations in the curing process and changes in the final sound speeds of up to ~3.6 %. The longitudinal and shear sound speeds were used to calculate the elastic properties of the material, including Young’s modulus and Poisson’s ratio. Finally, the curing kinetics were modeled using the Hill equation to better understand numerically the effect of varying stoichiometry in the curing process. This approach has the potential to non-destructively characterize the properties of polymers in both an in-field and manufacturing setting, aiding in the tailoring process and ensuring their reliability in demanding applications.

The increasing occurrence of extreme weather events is challenging power grid operation. For extreme weather events, the system operator is responsible for estimating the power outages and scheduling the restoration resources. This paper proposes an outage evaluation framework to identify the possible unserved load profiles, vulnerable areas, and mobile energy adequacy. The outputs of an outage prediction model tool are used to generate numerous faulted line scenarios. Next, each scenario's nodal unserved load profile is obtained by solving a three-phase restoration model that considers repair crews and mobile energy resources (MERs). Then, a novel scenario clustering strategy is developed to cluster the unserved load profiles into multiple representative profiles which the system operator can focus on. Finally, case studies on a distribution system evaluate the damage caused by an extreme weather event and verify the effectiveness of the proposed scenario clustering strategy.

In this study, n-type CdTe thin films, specifically iodine-doped CdTe (CdTe:I), indium-doped CdTe (CdTe:In), and indium-doped Cd-Se-Te (CST:In), were synthesized using close-spaced sublimation epitaxy (CSSE). Characterization techniques secondary ion mass spectrometry (SIMS), electron backscatter diffraction (EBSD), Hall-effect measurements, and time-resolved photoluminescence (TRPL) were employed to analyze the chemical, structural, and electronic properties of these materials. The results indicated epitaxial single crystal CSSE films grew on the single crystal substrates, with carrier density ranging from 10^14 - 10^16 cm -3 , and after post-annealing, the minority-carrier lifetimes reach near the radiative limit. Additionally, a preliminary exploration of homojunction structures with an n- type (CdTe:In /CST:In /CdTe:I) /CdTe:P /Cu /Mo configuration was performed. The best device performance was achieved with CdTe:I including CdS aiding in band alignment, resulting in a power conversion efficiency (..eta..) of 2.61% with open circuit voltage (Voc) of 850 mV, fill factor (FF) of 47.8%, and short-circuit current (Jsc) of 6.44 mA/cm 2 . The observed low Jsc and efficiency may be attributed to a buried junction and a poor interface, due to dopant interdiffusion. Consequently, further investigations focusing on interface optimization, diffusion blocking, and reduced recombination through passivation, are crucial to enhancing the efficiency of CSSE CdTe homojunction devices in the future.

As newer cells structures come online, the pressing need to replace silver in the metallization pastes has renewed interest in alternative technologies employing base metals. Copper typically leads the charge with its abundance and lower cost but has faced numerous obstacles from relatively higher oxidation and diffusion rates which can damage the lifetime of the devices. In this study, a low-cost alternative to silver metallization pastes has been shown on PERC cells. The screen printable copper paste can be fired in air at temperatures >500 degrees C, and the impact of processing conditions and equipment on the performance and reliability of 274 cm2 cells have been evaluated. Through damp heat testing of micro-modules using 16 cm2 cells, routes that can lead to both the failure and success of durable contacts have been demonstrated.

Nuclear technology applications, including reactor modeling, accelerator design, and isotope production, strongly depend on evaluated nuclear data libraries and their uncertainty information for the assessment of predictive accuracy of calculated quantities. Major nuclear data libraries such as JENDL-5, JEFF-3.3, and ENDF/B-VIII.0 lack uncertainty information for n+ ¹⁸¹Ta reactions. In addition to the lack of evaluated uncertainty information even in major nuclear data library releases, the most current US ENDF/B-VIII.0 evaluation of the unresolved resonance region (URR) does not extend to high enough energies to appropriately account for resonance self-shielding effects. This work addresses these shortcomings through a new evaluation of the URR, performed with the SAMMY evaluation tool, which extends the evaluation of the URR to encompass neutron energies of 2.5 keV to 100 keV. This study reports evaluated covariances and includes newly measured data in the evaluation analysis that were unavailable to previous evaluators. The new evaluation was designed to be closely coupled to the resolved resonance region evaluation to improve consistency across multiple evaluation regions. The updated cross sections in the URR have reduced capture and total cross sections, which improve agreement with differential measurements compared to ENDF/B-VIII.0, but they deviate slightly further from integral benchmarks.

The Mississippian-age Caney Shale is an emerging unconventional oil and gas (UOG) resource play in the southern Midcontinent and is prospective in the Anadarko, Ardmore, Marietta and western Arkoma basins. This play is enigmatic in that time equivalent Fayetteville Shale in the eastern Arkoma basin and Barnett Shale in the Ft. Worth Basin are major unconventional plays, whereas Caney Shale production is sparse and unpredictable (Cardott, 2017). In the Anadarko, Ardmore and Marietta basins, the Caney Shale is in the oil window, but its resource potential has not been adequately assessed. The Caney reservoir is about 60-300 m thick, is rich in total organic carbon, contains a large oil resource base, and has a strong natural gas drive; however, development has been hampered by high clay content and reactivity of the formation with water. The main objective of this initial four-year research project was to address these issues by establishing a Caney Shale Field Laboratory in the Ardmore Basin of southern Oklahoma to (a) conduct a comprehensive field characterization (b) perform field experiments, and (c) validate cost-effective technologies that will lead to a comprehensive and efficient development strategy plan for Caney Shale.

Dual-use power converter cells can receive solar and laser power simultaneously to generate current, an application relevant to space and terrestrial industries. This study investigates two concepts of solar cells optimized for dual-use 1070 nm laser and solar power conversion, a single-junction and triple-junction cell. Because it is bandgap-tuned for a 1070 nm laser, the 1.1 eV junction is incorporated into each of the two designs, making its development key to the success of both concepts. Efficiency data for a one junction GaInAs cell demonstrates a laser conversion efficiency of 38% at 1070nm wavelength without an anti-reflection coating. However, the single-junction device requires optimization to reduce short wavelength absorption of the broad solar spectrum. In both devices, the graded buffer layers in the GaInAs cell affects the cell's performance by reducing threading dislocations in the active junction. However, the buffer in the three-junction device also acts as a lateral transport layer and so affects the fill factor depending on its sheet resistance. By varying the buffer thickness, we demonstrate a direct relationship between buffer thickness and sheet resistance reduction, while considering implications to open-circuit voltages. We also performed resistance modeling to determine the optimal grid spacing and thickness of the grid fingers to minimize losses due to sheet resistance and grid shading.

In this work, we present the performance and reliability of a fire-through copper (Cu) paste which has been screen printed on c-Si solar cell with passivated emitter rear contact (PERC). The Cu paste is fired through silicon nitride (SiN) anti-reflection coating at a peak temperature of 630 degrees C . SEM images of the Cu paste show a Cu core with ~200 nm oxide shell around the particles. This conductive oxide layer acts as a diffusion barrier between Cu and Si and prevents the degradation of cell performance during accelerated aging conditions. An efficiency of 19.250% has been achieved with Voc=654mV,FF= 76.68%, Jsc=38.40 m.A/cm 2 for champion PERC cells. Accelerated testing of the PERC mini-modules in damp heat chamber with 85 degrees C and 85% humidity have demonstrated that the devices are operational even after 1,500 hours. Devices with screen printed Ag contacts on the front side have been studied in parallel to the Cu contacts for comparison.

The increasing occurrence of extreme weather events is challenging power grid operation. For extreme weather events, the system operator is responsible for estimating the power outages and scheduling the restoration resources. This paper proposes an outage evaluation framework to identify the possible unserved load profiles, vulnerable areas, and mobile energy adequacy. The outputs of an outage prediction model tool are used to generate numerous faulted line scenarios. Next, each scenario's nodal unserved load profile is obtained by solving a three-phase restoration model that considers repair crews and mobile energy resources (MERs). Then, a novel scenario clustering strategy is developed to cluster the unserved load profiles into multiple representative profiles which the system operator can focus on. Finally, case studies on a distribution system evaluate the damage caused by an extreme weather event and verify the effectiveness of the proposed scenario clustering strategy.