Variable Pressure Conditions Research Articles

Design and experimentation of a pressure testing platform for tea tree canopy

In the mechanized operations of tea gardens, components like cutting blades and suspension systems frequently interact with the tea tree canopy, resulting in complex push, squeeze, and pressure interactions. This makes it challenging to accurately measure the distribution characteristics of the forces involved. The uncertainty in these mechanical properties complicates mechanical design, posture adjustment, and positioning control. To address this, this study designed and developed a testing platform for pressure measurement in the tea tree canopy, aiming to systematically investigate the force characteristics and structural changes of the canopy under different penetration depths. The platform enabling high-precision recording of canopy responses under varying pressure conditions. The experimental results indicated significant differences in pressure values at different depths and locations. At a penetration depth of 1.0 cm, the minimum pressure value was 3.0 N, while the maximum pressure at a depth of 4.0 cm reached 60.0 N. Moreover, the pressure exhibited a clear hierarchical distribution with changes in depth and position. The study observed a hierarchical structure within the tea tree canopy, comprise tender leaves, mature leaves, and branches. These findings provide important evidence and data support for the optimization of tea garden management and harvesting machinery design.

Numerical investigation of fluid–structure interaction in a pilot-operated microfluidic valve

The present paper is concerned with numerical investigation of the performance of a pilot-operated control valve based on shape memory alloy actuation control. The valve under investigation can be integrated into miniaturized hydraulic systems and is developed to perform precise dispensing, mixing, or dosing tasks while being able to withstand relatively high pressure differences. The study evaluates the valve’s response under the current ON/OFF and the desired proportional control regimes using numerical methods for fluid–structure interaction. The computational model replicates the operation of the valve, which requires an understanding of the complex interactions between the fluid flow with the pressurized valve and the contact with the valve seat during the opening and closing processes. In addition, the model leverages advanced numerical techniques to overcome several complexities arising mainly from the geometrical, material, and contact nonlinearities, and to mitigate the shortcomings of the partitioned fluid–structure interaction approach. Several 3D fluid–structure-contact-interaction simulations are conducted to examine the valve’s structural and flow behavior under varying pressure conditions. Results indicate that the valve is adequate for ON/OFF actuation control but is susceptible to flow-induced vibrations during the proportional control regime that occurs due to the sharp pressure drop in the valve-seat gap and the ensuing Venturi effect, which counteract the opening of the main valve. The fluid–structure-interaction simulations provide insight into the mechanism underlying the flow-induced vibrations, which can serve to improve the design and enhance the performance of the valve in microfluidic applications.

Non-intrusive experiments on coupled bubble dynamics and heat transfer during nucleate boiling under varying pressure conditions

The experimental investigation is concerned with the dynamics of single vapor bubble and heat transfer during nucleate boiling under varying pressure conditions, encompassing both atmospheric and sub-atmospheric levels. Utilizing high-speed rainbow schlieren deflectometry, a non-intrusive imaging technique for visualizing and quantifying the flow field variables in the fluid medium, this research examines the influence of operating pressure on some of the important parameters pertaining to boiling phenomenon such as bubble size, shape, and detachment mechanisms. The observations show that a decrease in pressure leads to the formation of larger bubbles, which, in turn, alters their growth mechanism. These changes in bubble behavior have a significant influence on the various forces acting on the growing bubble as well as on the associated heat transfer rates. The analysis provides insights into the complex interplay between buoyancy, surface tension, growth and contact pressure forces. Change in pressure significantly impacts these forces, influencing bubble dynamics. Moreover, the study presents a quantitative analysis of the whole field temperature distribution and heat transfer rates throughout the boiling process. Results reveal a strong dependence of thermal field on the working pressure, with higher pressures leading to more uniform temperature distributions. Evaporative component of heat transfer from the bubble base and convective heat transfer from the superheated layer are identified as the dominant mechanisms. Natural convection initially dominates, decreases post-nucleation, and increases upon bubble departure due to the fluid quenching effects.

Characterization of Stages of CO2-Enhanced Oil Recovery Process in Low-Permeability Oil Reservoirs Based on Core Flooding Experiments

Understanding the CO2 displacement mechanism in ultra-low-permeability reservoirs is essential for improving oil recovery. In this research, a series of displacement experiments were conducted on sandstone core samples from the Chang 6 reservoir in the Huaziping area using a multifunctional core displacement apparatus and Nuclear Magnetic Resonance (NMR) technology. The experiments were designed under conditions of constant pressure, variable pressure, and constant effective confining stress to simulate various reservoir scenarios. The results indicated that the distribution characteristics of the pore structure in the rock samples significantly influenced the CO2 displacement efficiency. Specifically, under identical conditions, rock cores with a higher macropore ratio exhibited a significantly enhanced recovery rate, reaching 68.21%, which represents a maximum increase of 31.97% compared to cores with a lower macropore ratio. Though fractures can facilitate CO2 flowing through pores, the confining pressure applied during displacement caused a partial closure of fractures, resulting in reduced rock permeability. Based on the oil-to-gas ratio and oil recovery in the outlet section of the fractured rock samples, the CO2 displacement process exhibited five stages of no gas, a small amount of gas, gas breakthrough, large gas channeling, and gas fluctuation. Although the displacement stage of different cores varies, the breakthrough stage consistently occurs within the range of 2 PV. These insights not only enhance our understanding of CO2 displacement mechanisms in low-permeability reservoirs but also provide actionable data to inform the development of more effective CO2-EOR strategies, significantly impacting industrial practices.

A Discovery of Pressure-Induced New Semiconductor Electronic Phase Transitions by DFT Calculations: Introducing a Glimpse of a Novel Semiconductor Family.

This study introduces a discovery of pressure-induced new semiconductor electronic phase transitions. A novel semiconductor family that exhibits pressure-induced nonmonotonic changes in band gaps was found and meets the definition of phase transitions, challenging the traditional understanding of linear and monotonic band gap modification through pressurization. Our findings suggest a complex interplay of atomic spacing and electron orbital contributions under varying pressure conditions, resulting in the variation of band gaps. This behavior, which includes three distinct steps: first, narrowing, second, broadening, and third, narrowing again and ultimately metalizing; some compounds could bypass step 1, has potential applications in piezoelectric and semiconductor technologies. We propose two new semiconductor electronic phase transitions (SEPT) associated with specific inflection points in the pressure-dependent band gap curve. Our results open avenues for further research into the electronic properties of crystals under high pressure, with the ultimate goal of uncovering the more profound physical principles governing these phenomena.

Phase-transition of hydrophobic dipeptide l-phenylalanyl-l-alanine under high pressure via Raman spectroscopy

The study conducted on l-Phenylalanyl-l-Alanine (C12H16N2O3) dehydrated crystals under high-pressure conditions up to 7.0 GPa using Raman spectroscopy revealed significant modifications in both lattice and internal modes. Particularly, alterations were observed in modes associated with carbonyl and NH2 functionalities around 1600 cm−1. The Raman spectra exhibited distinct changes in modes related to torsions and stretching of the ring, suggesting a potential conformational change in specific pressure intervals: 2.6–3.0 GPa, and 5.0–5.1 GPa. Furthermore, notable changes between 0.4 and 1.0 GPa hinted at a structural transformation in the crystal. Additionally, Scanning Electron Microscopy-Field Emission Gun (SEM-FEG) was employed to elucidate the crystal pattern of Phe-Ala·2H2O. The ambient study, incorporating calculations, infrared, and Raman spectroscopy, contributed to a comprehensive understanding of vibrational mode assignments. This research sheds light on the behavior of l-Phenylalanyl-l-Alanine dehydrated crystals under varying pressure conditions, offering valuable insights for medicinal and pharmacological applications.

Non-Isothermal Thermogravimetric Analysis of Carbonation Reaction for Enhanced CO2 Capture

An in-depth investigation into CaO-based carbonation reaction kinetics for CO2 sorption is being conducted using simultaneous thermal analysis (STA), with the application of advanced thermogravimetric and differential scanning calorimetry techniques. Utilizing advanced thermal analysis system for real-time monitoring of simultaneous measurements of mass changes and thermal effects are conducted, ensuring precision and versatility in data acquisition. The study explores the intricacies of the non-isothermal carbonation process across a wide range of temperatures, shedding light on the temperature-dependent trends in reaction rates. Innovative statistical methods, combining regression techniques and Arrhenius equation, are employed to determine energy and reaction kinetics. The sensitivity of carbonation process to varying pressure conditions is meticulously examined in the study, providing pivotal discernment for optimization of reaction parameters across diverse applications. The integration of STA with statistical modeling alongside systematic analysis of temperature-dependent trends and pressure-order relationships not only enhances the understanding of CO2 capture efficiency but also improves the robustness and accuracy of the findings. Furthermore, meticulous cross-validation with existing studies provides a critical evaluation of the experimental approach’s precision and limitations. This study enhances understanding of CaO carbonation kinetics, providing practical implications for carbon capture processes and contributing to sustainable industrial processes.

Finite Element Analysis and Computational Fluid Dynamics for the Flow Control of a Non-Return Multi-Door Reflux Valve

This paper presents a comprehensive analysis of a multi-door check valve using computational fluid dynamics (CFD) and finite element analysis (FEA) to evaluate flow performance under pressure test conditions, with an emphasis on its ability to prevent backflow. Check valves are essential components in various industries, ensuring fluid flow in one direction only while preventing reverse flow. The non-return multi-door reflux valve is increasingly preferred due to its superior backflow prevention, fluid control, and effective flow regulation. Rigorous testing under varying pressure conditions is essential to ensure that these valves perform optimally. This study uses CFD and FEA simulations to evaluate the structural integrity and flow characteristics of the valve, including pressure drop, flow velocity, backflow prevention effectiveness, and flow coefficient. A high-fidelity 3D model was created to simulate the valve’s behavior under various conditions, analyzing the effects of parameters such as the number of doors, their orientation, geometry, and operating conditions. The CFD results demonstrated a significant reduction in backflow and pressure drop across the valve. However, localized turbulence and flow separation near the valve doors, particularly under partially open conditions, have raised concerns about potential wear. The velocity profiles indicated a uniform distribution at full opening with laminar velocity profiles and minimal resistance to flow. The results of the FEA showed that the stresses induced by the fluid forces were below critical levels, with the highest stress concentrations observed around the hinge points of the valve doors. Although the valve structure remained intact under normal operating conditions, some areas may have required reinforcement to ensure long-term durability. Combined CFD and FEA analyses demonstrated that the valve effectively preserves system integrity, prevents backflow, and maintains consistent performance under various pressure and flow conditions. These findings provide valuable insights into design improvements, performance optimization, and enhancing the efficiency and reliability of reflux valve systems in industrial applications.

Impact of Overpressure on the Preservation of Liquid Petroleum: Evidence from Fluid Inclusions in the Deep Reservoirs of the Tazhong Area, Tarim Basin, Western China

The complexity of petroleum phases in deep formations plays an important role in the evaluation of hydrocarbon resources. Pressure is considered to have a positive impact on the preservation of liquid oils, yet direct evidence for this phenomenon is lacking in the case of deep reservoirs due to late destruction. Here, we present fluid-inclusion assemblages from a deep reservoir in the Tazhong area of the Tarim Basin, northwestern China, which formed as a direct consequence of fluid pressure evolution. Based on thermodynamic measurements and simulations of the coexisting aqueous and petroleum inclusions in these assemblages, the history of petroleum activities was reconstructed. Our results show that all analyzed fluid-inclusion assemblages demonstrated variable pressure conditions in different charging stages, ranging from hydrostatic to overpressure (a pressure coefficient of up to 1.49). Sequential petroleum charging and partial oil cracking may have been the main contributors to overpressure. By comparing the phases of petroleum and fluid pressures in the two wells, ZS1 and ZS5, it can be inferred that overpressure inhibits oil cracking. Thus, overpressure exerts an important influence on the preservation of liquid hydrocarbon under high temperatures. Furthermore, our results reveal that the exploration potential for liquid petroleum is considerable in the deep reservoirs of the Tarim Basin.

On the Bulk Photovoltaic Effect in the Characterization of Strained Germanium Microstructures

Strain engineering serves as an effective method for optimizing electronic and optical properties in semiconductor devices, with applications including the enhancement of optical emission in Ge and GeSn‐based devices, improvement of carrier mobility, and second harmonic generation in silicon photonics structures. Current methods for deformation characterization in semiconductors, such as X‐ray diffraction and Raman spectroscopy, often require bulky and expensive setups and are limited in vertical resolution. Consequently, techniques capable of measuring lattice strain while overcoming these drawbacks are highly desirable. This study proposes a proof of concept for a cost‐effective, compact, fast, and non‐destructive approach to probe non‐uniform strain fields and additional material properties by exploiting the bulk photovoltage effect. The method is benchmarked with an array of silicon nitride stripes deposited under varying pressure conditions on a germanium substrate. Initially, their surface strains are verified through Raman spectroscopy. The deformations are replicated in a finite element method platform by integrating mechanical simulations with deformation potential theory, thereby estimating the band edge energy landscape. Finally, the study discusses the theoretical behavior of the photovoltage signal, considering semiconductor properties, defects, doping, and deformation. The findings offer insights into the development of advanced techniques for strain and transport analysis in semiconductor materials.

Impact of variable hydrostatic pressure and intermittent operation on filtration performance and biofouling layer in gravity-driven membrane system for practical decentralized water supply

The gravity-driven membrane (GDM) systems offer a promising solution for decentralized drinking water supply due to its low maintenance and energy consumption. However, research on the practical application of GDM under variable hydrostatic pressure (variable load) and intermittent operation conditions, particularly in response to high-turbidity water, remains limited. This study investigates the long-term performance and characteristics of the biofouling layer of GDM under ultra-low variable hydrostatic pressure (20–60 mbar) and intermittent operation (8–12 h) conditions in practical decentralized water supply. The results indicate that the membrane flux (1.9–6.0 L∙m−2∙h−1, LMH) remained relatively stable despite variations in gravity-driven pressure (ΔP). Long-term operation of GDM can stably remove turbidity and potential pathogens from raw water. The total protein/polysaccharide ratios of extracellular polymeric substances (EPS) in the biofouling layer were below 0.50, reducing contaminant adhesion on the membrane surface. The 0.2–0.4 μm transparent exopolymer particles (TEP) fraction might be crucial for biofouling layer formation. The key species, belong to Proteobacteria and Patescibacteria, significantly alleviated membrane fouling by degrading polysaccharide and proteins in biofouling layer. Comammox Nitrospira were significantly enriched, contributing to efficient nitrification. GDM with variable load maintained a stable flux of 2.2–5.2 LMH under high-turbidity water conditions (300–1200 NTU), and simple forward flushing combined with sludge discharge can quickly restore ΔP. Overall, the variable load GDM system effectively manages membrane fouling and maintains stable filtration performance through the combined effects of variable load and intermittent operation, ensuring long-term and low-maintenance operation for decentralized water supply.

Comprehensive analysis of laminar burning velocity in DEK/NH3-air premixed flames under varied pressure conditions

3-pentanone (DEK) is a biomass oxygenated fuel with high energy density and low emissions. It shows promising potential in increasing the combustion of NH3. This study examines the laminar burning velocity (LBV) of a fuel mixture composed of DEK/NH3-air. The LBV of DEK/NH3-air was determined with a constant-volume combustion bomb under the following conditions: initial temperature (T) of 448 K, pressure (P) of 1 to 3 atm, equivalence ratio (ϕ) between 0.7 and 1.3, and NH3 mole fraction (XNH3) varying from 0 % to 90 %. A combustion kinetic model for DEK/NH3 mixed fuel was developed and verified using experimental results. Overall, the model can capture the trend of LBV well. Subsequently, a comprehensive kinetic analysis was conducted utilizing this mechanism to elucidate the effect of NH3 mixing on DEK/NH3-air mixed fuel. The results indicate that LBV of DEK/NH3-air mixture declines as XNH3 increases, primarily attributed to the reduction in radical pool concentration. Conversely, the effect of the decrease in flame temperature is relatively minor. Furthermore, as XNH3 mole fraction decrease, there is a slight alteration in the consumption pathway of NH3. The elevation in DEK mole fraction leads to an increased production of radicals, thereby amplifying the oxidation process of NH3. The proportion of the oxidation of NHi pathway also increases. Finally, the change of NO content in DEK/NH3-air flame was observed. The rise in XNH3 leads to a gradual increase in the content of NO until it reaches a peak, after which it starts to decline. This phenomenon is dependent on the presence of O, OH, and NHi radicals. In addition, it has been discovered that augmenting ϕ can significantly reduce the concentration of NO in DEK/NH3-air mixture.

Management of Vesicovaginal Fistula in Lower-Resource Settings: A Novel Device for Collection and Drainage of Urine

Abstract Treatment of vesicovaginal fistula (VVF) is currently limited to surgical repair that is costly and sparsely available and requires intervention from trained specialists, preventing patients in lower-resource settings from receiving effective care. As those who remain untreated continue to experience severe vaginal urinary leakage, an affordable, easy-to-use device that discreetly contains and redirects unwanted leakage of fluids would temporarily alleviate the social distress associated with VVF until patients can afford to present for treatment. We present a novel device to mitigate urinary leakage caused by VVF using a vaginal cup, which allows for the funneling and rerouting of urine into an external drainage bag, to be released at a user's convenience. For patients who cannot afford surgery, our device helps manage their symptoms so that they can reintegrate into society and no longer face the harrowing stigma of their family and society. We demonstrate the effectiveness of our device through preliminary benchtop testing, using a non-living vaginal model to verify leak-free retainment of the device under varying pressure conditions. Preliminary results indicate that the device displayed no circumferential leakage, and the internal displacement of the cup was within the allotted range of 5 mm for applied hydrostatic pressures up to 150 cm H2O.

Revealing the kinetic behaviors of hydrate formation on bubble surface with different pressure gradients in deep-sea methane seepage areas of the South China Sea

In the deep-sea methane seepage environment, hydrate formation on the methane bubbles is a crucial pathway for methane transformation, and plays an important role in determining whether seepage methane can enter the surface ocean. While how the pressure determines the hydrate formation process in different water depths remains unclear. In this study, we investigated the formation kinetic characteristics and microstructure evolution of methane hydrate on suspended gas bubbles within varied pressure conditions. The pressure range (4–14 MPa) was in the deep-sea methane seepage environment. The results indicated that pressure obviously affected the hydrate film formation characteristics. As pressure increased, the lateral growth rate of the hydrate film accelerated, the hydrate crystal particles became smaller, and the initial hydrate film surface became smoother. Raman spectroscopy results showed that pressure changes did not obviously alter the microporous evolution on the hydrate film surface, that the gas-phase/water-phase Raman peak area ratio exhibited similar trends. The dissolved methane concentration under different pressure conditions was not the primary factor affecting hydrate thickening, rather, it depended mainly on the driving force. This study is of great significance in revealing the characteristics of methane hydrate formation and methane transfer in the oceanic methane seepage environment.

An All‐in‐One Wearable Device Integrating a Solid‐State Zinc‐Ion Battery and a Capacitive Pressure Sensor for Intelligent Health Monitoring

AbstractThis study introduces a novel wearable device that combines dual‐functional modules for energy storage and sensing. The device features an ionic gel serving as both the battery electrolyte and sensor dielectric layer, along with VO2‐nanoneedles electrodes. The solid‐state zinc‐ion battery module demonstrates a specific capacity of 286 mAh g−1, delivering consistent and long‐lasting power output even under variable pressure conditions. Moreover, the iontronic pressure sensor module exhibits high sensitivity, achieving 2.3 × 104 kPa−1, enabling precise detection of fingertip pulses and identification of respiratory patterns. The device's flexibility and structural resilience allow it to endure complex deformations, ensuring continuous operation in challenging environments. These results highlight the potential of the all‐in‐one device for wearable smart healthcare monitoring and management.

Pressure-induced structural, electronic, optical, and mechanical properties of lead-free GaGeX3 (X = Cl, Br and, I) perovskites: First-principles calculation

Researchers are now focusing on inorganic halide-based cubic metal perovskites that are not toxic as they strive to commercialize optoelectronic products and solar cells derived from perovskites. This study explores the properties of new lead-free compounds, specifically GaGeX3 (where X = Cl, Br, and I), by executing first-principles Density Functional Theory (DFT) to analyze their optical, electronic, mechanical, and structural characteristics under pressure. Assessing the reliability of all compounds is done meticulously by applying the criteria of Born stability and calculating the formation energy. As discovered through elastic investigations, these materials showed anisotropic behavior, flexibility, and excellent elastic stability. The electronic band structures, calculated using both HSE06 and GGA-PBE functionals at 0 GPa, reveal fascinating behavior. However, computed band structures with non-zero pressures using GGA-PBE. Here, the conduction band moved to the lower energy when the halide Cl was changed with Br or I. In addition, the application of hydrostatic pressure can lead to tunable band gap properties in all compounds such as from 0.779 eV to 0 eV for GaGeCl3, from 0.462 eV to 0 eV for GaGeBr3 and from 0.330 eV to 0 eV for GaGeI3, resulting transformation from semiconductor to metallic. Understanding the origins of bandgap changes can be illuminated by examining the partial and total density of states (PDOS & TDOS). When subjected to pressure, all the studied compounds showed an impactful increase in absorption coefficients and displayed exceptional optical conductivity in both the visible and UV zones. Yet, GaGeCl3 is a more effective UV absorber because it absorbs light more strongly in the UV area. Moreover, GaGeI3 stands out among the compounds examined due to its impressive visible absorption and optical conductivity, which remain consistent under varying pressure conditions. Besides, GaGeI3 exhibits higher reflectivity when subjected to pressure making them suitable for UV shielding applications. At last, these metal cubic halide perovskites without lead present promising opportunities for advancing optoelectronic technologies. With their tunable properties and favorable optical characteristics, these materials are highly sought after for their potential in solar cells, multi-junctional solar cells, and different optoelectronic functions.

Synchrotron vacuum ultraviolet photoionization mass spectrometry and modeling study of iso-octane low temperature oxidation at varied pressures

Because of its excellent anti-knock properties, iso-octane has been selected as the main component of gasoline surrogates, and a thorough understanding of its low temperature oxidation process is essential for the development of kinetic models. Although iso-octane has been studied for decades, a comprehensive understanding of its low temperature oxidation chemistry has not been realized, and kinetic models were not well developed. In this work, the previously developed, variable pressure jet-stirred reactor-synchrotron vacuum ultraviolet photoionization mass spectrometry system was used to study the low temperature oxidation of iso-octane at five bar, with an initial fuel mole fraction of 0.01, residence time of 2 s, and equivalence ratio of 0.25. Dozens of oxidation intermediates were qualitatively and quantitatively analyzed, helping to reveal the low temperature oxidation reaction processes of iso-octane and examine the kinetic models. Comparing iso-octane studies at high pressure in the literature, a highly detailed species pool was probed, which included H2O2, carbonyl acids, alkyl hydroperoxides, and keto-hydroperoxides (KHP). By combining the atmospheric pressure data in the literature, the recently developed model of iso-octane low temperature oxidation was examined. Further improvement of the kinetic model was achieved by carefully tuning the reaction rate constant of the KHP decomposition. Finally, according to the variation of mole fraction of products at different pressures, the pressure effects on key reaction pathways were discussed, and the selectivity of products at varied pressure conditions clarified.

Exploring negative ion behaviors and their influence on properties of DC magnetron sputtered ITO films under varied power and pressure conditions

Abstract We deposited indium-tin-oxide (ITO) films on silicon and quartz substrates by magnetron sputtering technology in pure argon. Using electrostatic quadrupole plasma diagnostic technology, we investigate the effects of discharge power and discharge pressure on the ion flux and energy distribution function of incidence on the substrate surface, with special attention to the production of high-energy negative oxygen ions, and elucidate the mechanism behind its production. At the same time, the structure and properties of ITO films are systematically characterized to understand the potential effects of high energy oxygen ions on the growth of ITO films. Combining with the kinetic property analysis of sputtering damage mechanism of transparent conductive oxide (TCO) thin films, this study provides valuable physical understanding of optimization of TCO thin film deposition process.

Tuning band gaps in lead chalcogenides under pressure: implications for infrared detection applications

This study employs first-principle calculations within density functional theory (DFT) to explore the structural, electronic, optical, and thermoelectric properties of lead chalcogenides (PbS, PbSe, and PbTe). The investigation focuses on their potential application as infrared photodetectors, leveraging their narrow-band gap semiconductor characteristics. The influence of pressure on the band gap and various electronic, optical, and thermoelectric properties is thoroughly analyzed. The calculated band gap values for PbS, PbSe, and PbTe are determined to be 0.29 eV, 0.18 eV, and 0.18 eV, respectively, aligning well with experimental data. Notably, the study reveals non-linear changes in band gap values under pressure, with phase transitions observed at specific pressure thresholds in PbS and PbSe, but not in PbTe. Under varying pressure conditions, the optical peaks shift towards lower energy levels with increased intensity. The static dielectric constant of PbS, PbSe, and PbTe exhibits distinct variations within pressure ranges of 0–8 GPa. Transport coefficients (S, σ, ke) are calculated using semi-classical Boltzmann theory across different temperatures and pressures, indicating that heavier compounds exhibit higher electrical and thermal conductivity values. At 300 K, the maximum ZT values are determined to be 0.85, 0.8, and 0.52 for PbS, PbSe, and PbTe, respectively. The study suggests enhanced thermoelectric properties of these structures at lower temperatures, particularly highlighting PbS and PbSe as promising candidates for thermoelectric applications below 500 K. Exploring the impact of pressure on the thermoelectric parameters of lead chalcogenides reveals interesting trends, with PbTe demonstrating higher thermoelectric efficiency under increased pressure compared to PbS and PbSe. These findings provide valuable insights into the potential applications and performance of lead chalcogenides in IR detection and thermoelectric systems.

Optimized Fabrication Process and PD Characteristics of MVDC Multilayer Insulation Cable Systems for Next Generation Wide-Body All-Electric Aircraft

For wide-body all-electric aircraft (AEA), a high-power-delivery, low-system-mass electric power system (EPS) necessitates advanced cable technologies. Increasing voltage levels enhances power density yet poses challenges in aircraft cable design, including managing arc-related risks, partial discharges (PDs), and thermal management. Developing multilayer multifunctional electrical insulation (MMEI) systems for aircraft applications is a feasible option to tackle these challenges and reduce the size and mass of cable systems. This approach involves selecting layers of different materials to address specific challenges. Our prior research concentrated on the modeling and simulation-based design of MMEI systems for MVDC power cables. Experimental tests are essential for determining the behavior of PDs under varying pressure conditions. Also, the dielectric strength and time to failure of the designs need to be assessed. In this work, the fabrication process of a down-selected MMEI flat configuration is discussed and analyzed. This paper analyzes the fabrication process of power cables employing MMEI configurations and evaluates the PD characteristics of down-selected ARC-SC-T-MMEI cable samples. This study presents a detailed analysis of the characteristics of PD under atmospheric and low-pressure conditions, which will provide essential insights into the design of MVDC cables for future AEA applications.