bluuebunny/crossref_metadata_2025 huggingface dataset:
Origin of the Ukrainian minority of Kazakhstan as inferred from HLA‐A, ‐B, ‐C, ‐DRB1, and ‐DQB1 alleles and haplotypes distribution
Authors: Hajjej Abdelhafidh , Abdrakhmanova Saniya , Turganbekova Aida , Almawi Wassim Y.
Published: July 2021

The present‐day population of Kazakhstan comprises more than 100 ethnic and linguistic groups, of which Ukrainians rates numerically as the fourth, following native Kazakhs, Russians, and Uzbeks. We investigated the HLA profile of Kazakhstani Ukrainians and compared them with those of other populations by applying genetic distances, correspondence analysis, admixture, and haplotype examination. Of the 128 HLA alleles identified, A*02:01 (28.64%), B*07:02 (9.71%), B*13:02 (9.71%), C*06:02 (15.05%), DRB1*07:01 (15.20%), and DQB1*03:01 (24.76%) were the utmost common alleles. The most common 2‐locus haplotypes identified were A*02:01 ~ B*13:02 (6.66%), B*13:02 ~ DRB1*07:01 (6.57%), B*13:02 ~ C*06:02 (10.10%), and DRB1*01:01 ~ DQB1*05:01 (12.12%), while A*02:01 ~ B*13:02 ~ C*06:02 ~ DRB1*07:01 ~ DQB1*02:01 were the most frequent five‐locus haplotype (4.04%) in Kazakhstani Ukrainians. Comparative analysis revealed that Ukrainians of Kazakhstan are closely related to Eastern Europeans (included Ukrainians), and European Russians, but distant from Asian populations. This supports the historical notion that Kazakhstani Ukrainians originated from Ukraine, following their massive migrations to central Asia in the 18th–20th centuries.
Foragers and Their Tools: Risk, Technology and Complexity
Authors: Sterelny Kim
Published: July 2021

The subsistence technology of forager communities has varied greatly over space and time. This paper (i) reviews briefly the main causal factors the literature identifies as responsible for this variation; (ii) analyzes in some detail the most prominent idea in the literature on spatial variation:Complex technology is an adaptive response to elevated risks of subsistence failure; (iii) it argues that the alleged empirical support for this hypothesis depends on dubious proxies of risk; (iv) it argues that it fails to explain the subsistence technologies of desert foragers, who generally live with simple technologies in high‐risk environments; (v) it offers an alternative analysis, based on the reduced opportunity costs of complex technologies in highly seasonal environments, on the high value of typical forager targets in those environments and their relatively predictable location in space and time; and (v) the paper concludes with a conjecture about the role of environmental variation in toolkit change over deep time.
Alone on an island: The reassessment of an enigmatic species of Handmaiden Moth (Lepidoptera, Erebidae) endemic to Mauritius
Authors: Przybyłowicz Łukasz , Wiorek Marcin , Przystałkowska Anna , Wahlberg Niklas
Published: July 2021

Maculonaclia florida (de Joannis, 1906) has been one of the most mysterious moths of Mauritius, a small volcanic island located some 900 km east from Madagascar. Here, we reviewed its generic placement, phylogenetic relationships and the potential evolutionary scenarios leading to the current distribution of this unique Mauritian member of Syntomini. The species, known previously only from a few old museum specimens, is redescribed based on newly collected material including both sexes and eggs. The generic affiliation to the Palaearctic Dysauxes is confirmed based on morphological and molecular data. A hypothesis is presented on the colonization of Mauritius by the ancestor of D. florida from Madagascar through the now submerged stepping stone islands of the Mascarene ridge. Behavioural data and environment preferences of D. florida are assessed for the first time. The species prefers shrubby vegetation with a humid understory, and presence of endemic shrub Ixora parviflora seems to play a role in selecting the suitable microhabitat. Additionally, based on IUCN criteria, a CR threat category is proposed, highlighting the major risk factors affecting the species. The significant variation in wing venation of D. florida is noted and provisionally correlated with environmental stress, which is the consequence of human‐caused habitat degradation. Finally, the study provides further evidence for the significant role of Madagascar in the diversification of continental biota, indicating a Malagasy origin of the African syntomine Pseudonaclia puella.
WILLEM DREES ON THE HUMANITIES
Authors: Ruse Michael
Published: July 2021

Do universities still need departments in the humanities—philosophy, history, languages, and so forth? Many today, particularly legislators with control over the funding of public universities, feel that the emphasis should be on, and only on, departments in the STEM field. Willem B. Drees, a former dean of humanities, makes a spirited defense of the worth of the humanities and of their continued place in higher education. This essay looks at Drees's arguments in a critical, yet appreciative, fashion. It is a debate we need to have.
THEOLOGY AMONG THE HUMAN HUMANITIES
Authors: Ottati Douglas F.
Published: July 2021

This essay indicates how theology of a certain sort may contribute to the “human humanities” as Willem B. Drees understands them, but also that there is no single entirely satisfactory solution to the question of how to give due attention to the intensely self‐involving character of plural religions. The best we can do is to undertake theology, religious studies, and philosophy of religion in proximity to one another. This helps to maintain the sense that, in the humanities generally and the study of religion specifically, we not only develop comparative and disciplined reflections that aspire to a measure of neutrality, but also invite persons to undertake inherently self‐involving and reflexive inquiries, including theological ones.
Share Pledging and Firm Cash Holdings: Evidence from Chinese A-share Listed Firms
Authors: Xu Hongmei
Published: July 2021

This paper examines the relation between share pledging and cash holdings of Chinese A-share listed-firms. We find that during the years 2005 through 2015, the level of share pledging is negatively associated with cash holdings. We establish causality through a variety of econometric techniques, including a difference-in-differences approach based on a regulatory change that permits security companies to lend money to borrowers pledging their shares as collaterals. In addition, we find that the main effect is more prominent for financial constrained firms, and share pledging is associated with lower cash/investment-cash flow sensitivities and more cash dividend payouts. Overall, our findings indicate that share pledging can alleviate financial constraints of listed firms and reduce their tendencies of holding cash for precautionary motives.
Dense Suspension Flows: A Mathematical Model Consistent With Thermodynamics
Authors: Shelukhin Vladimir V. , Neverov Vladimir V.
Published: July 2021

We address the flows of dense suspensions of particles within the framework of two-velocity continuum. Thermodynamics of such a continuum is developed by the method suggested in the papers of Landau and Khalatnikov. As an application, we consider the convective settling problem. We capture the Boycott effect and prove that the enhanced sedimentation occurs in a tilted vessel due to vortices. We do not call on additional interphase forces like the Stokes drag, the virtual mass force, the Archimedes force, the Basset-Boussinesq force and etc. Instead, we apply a generalized Fick's law for the particle mass concentration flux vector.
Unveiling the Flow Behavior Inside Gasoline Direct Injection Engine Cylinder Using High-Speed Time-Resolved Particle Image Velocimetry and Computational Fluid Dynamics Simulation
Authors: El-Adawy Mohammed , Heikal M. R. , Aziz A. Rashid A.
Published: July 2021

ricardo-vectis computational fluid dynamics simulation of the in-cylinder air flow was first validated with those of the experimental results from high-speed particle image velocimetry (PIV) measurements taking cognizant of the midcylinder tumble plane. Furthermore, high-speed fuel spray measurements were carried out simultaneously with the intake-generated tumble motion at high valve lift using high-speed time-resolved PIV to chronicle the spatial and time-based development of air/fuel mixture. The effect of injection pressure(32.5 and 35.0 MPa) and pressure variation across the air intake valves(150, 300, and 450 mmH2O) on the interaction process were investigated at a valve lift 10 mm where the tumble vortex was fully developed and filled the whole cylinder under steady-state conditions. The PIV results illustrated that the intake generated-tumble motion had a substantial impact on the fuel spray distortion and dispersion inside the cylinder. During the onset of the injection process, the tumble motion diverted the spray plume slightly toward the exhaust side before it followed completely the tumble vortex. The fuel spray plume required 7.2 ms, 6.2 ms, and 5.9 ms to totally follow the in-cylinder air motion for pressure differences 150, 300, and 450 mmH2O, respectively. Despite, the spray momentum was the same for the same injection pressure, the magnitude of kinetic energy was different for different cases of pressure differences and subsequently the in-cylinder motion strength.
Superphénix Benchmark Part II: Transient Results
Authors: Ponomarev A. , Mikityuk K. , Fridman E. , Di Nora V. A. , Bubelis E. , Schikorr M.
Published: July 2021

The paper presents a transient simulation phase of the new benchmark on a large sodium fast reactor (SFR). This phase of the benchmark is devoted to the modeling of selected operational transients performed during startup tests of the French SFR Superphénix. Six operational transients were selected for the analysis. The specifications of a simplified thermal hydraulic model equipped with point kinetics reactivity data and boundary conditions for the selected transients are given in the paper. The developed model contains a necessary thermal hydraulic description of the primary system components, assumptions to account for thermal expansion reactivity feedback from out-of-core structures, neutron kinetics parameters, power distribution, and reactivity coefficients. The neutronic input parameters were obtained with the help of the Monte Carlo code serpent during the first phase of the benchmark related to the static neutronic characterization of the core. In this study, the solution of the transient benchmark was obtained with three thermal hydraulic system codes, namely, TRACE, SIM-SFR, and ATHLET. The numerical results, compared to the available experimental data, exhibit a reasonable mutual agreement. Particular discrepancies between calculations and experiments could not be fully resolved. Therefore, a set of recommendations for achieving an improved agreement was proposed. In general, the proposed transient benchmark can be seen as an effective tool for validation and cross comparisons of system codes applied for safety analyses of SFRs, including approbation and comparison of different modeling features for thermal expansion of the out-of-core structures.
Optimal Design of Integrated Distributed Energy Systems for Off-Grid Buildings in Different U.S. Regions
Authors: Zhang Jian , Cho Heejin , Mago Pedro
Published: July 2021

Off-grid concepts for homes and buildings have been a fast-growing trend worldwide in the last few years because of the rapidly dropping cost of renewable energy systems and their self-sufficient nature. Off-grid homes/buildings can be enabled with various energy generation and storage technologies, however, design optimization and integration issues have not been explored sufficiently. This paper applies a multi-objective genetic algorithm (MOGA) optimization to obtain an optimal design of integrated distributed energy systems for off-grid homes in various U.S. climate regions. Distributed energy systems consisting of renewable and non-renewable power generation technologies with energy storage are employed to enable off-grid homes/buildings and meet required building electricity demands. In this study, the building types under investigation are residential homes. Multiple distributed energy resources are considered such as combined heat and power systems (CHP), solar photovoltaic (PV), solar thermal collector (STC), wind turbine (WT), as well as battery energy storage (BES) and thermal energy storage (TES). Among those technologies, CHP, PV, and WT are used to generate electricity, which satisfies the building’s electric load, including electricity consumed for space heating and cooling. Solar thermal energy and waste heat recovered from CHP are used to partly supply the building’s thermal load. Excess electricity and thermal energy can be stored in the BES and TES for later use. The MOGA is applied to determine the best combination of DERs and each component’s size to reduce the system cost and carbon dioxide emission for different locations. Results show that the proposed optimization method can be effectively applied to design integrated distributed energy systems for off-grid homes resulting in an optimal design and operation based on a tradeoff between economic and environmental performance.
Preliminary Design, Analysis, and Cost Modeling of the Particle Handling System for a Pre-Commercial 26.5 MW-e Solid Particle Concentrated Solar Power Plant
Authors: Repole Kenzo , Alaqel Shaker , Jeter Sheldon , Al-Ansary Hany , Yeung Ryan , Sarfraz Muhammad
Published: July 2021

This paper covers the development of the preliminary design process, analysis, and cost modeling for the critical component specifications of a particle handling system, for a Pre-commercial 26.5 MW-e solid Particle Heating Receiver (PHR) based Concentrated Solar Power (CSP) systems in the Middle East North Africa (MENA) region.
Receiver Outlet Temperature Control for Falling Particle Receiver Applications
Authors: Schroeder Nathan , Laubscher Henk , Mills Brantley , Ho Clifford K.
Published: July 2021

Falling particle receivers (FPRs) are being studied in concentrating solar power applications to enable high temperatures for supercritical CO2 (sCO2) Brayton power cycles. The falling particles are introduced into the cavity receiver via a linear actuated slide gate and irradiated by concentrated sunlight. The thickness of the particle curtain associated with the slide-gate opening dimension dictates the mass flow rate of the particle curtain. A thicker, higher mass flow rate, particle curtain would typically be associated with a smaller temperature rise through the receiver, and a thinner, lower mass flow rate, particle curtain would result in a larger temperature rise. Using the receiver outlet temperature as the process variable and the linear actuated slide gate as the input parameter a proportional, integral, and derivative (PID) controller was implemented to control the temperature of the particles leaving the receiver. The PID parameters were tuned to respond in a quick and stable manner. The PID controlled slide gate was tested using the 1 MW receiver at the National Solar Thermal Test Facility (NSTTF). The receiver outlet temperature was ramped from ambient to 800°C then maintained at the setpoint temperature. After reaching a steady-state, perturbations of 15%–20% of the initial power were applied by removing heliostats to simulate passing clouds. The PID controller reacted to the change in the input power by adjusting the mass flow rate through the receiver to maintain a constant receiver outlet temperature. A goal of ±2σ ≤ 10°C in the outlet temperature for the 5 minutes following the perturbation was achieved.
Dynamic Simulation of Organic Rankine Cycle-Assisted Ground-Source Heat Pump Based Micro-Cogeneration System in Cold Climates: A Case Study in Canada
Authors: Yaïci Wahiba , Entchev Evgueniy , Longo Michela
Published: July 2021

As the energy needed for heating and cooling involves a substantial amount (> 80%) of residential energy utilisation in Canada, there is a demand for ultra-efficient energy systems for heating, cooling, and power generation. Two efficient systems to assist these systems are ground-source heat pumps (GSHPs) and organic Rankine cycles (ORCs). Of particular interest, this paper presents the integration of these two systems in a parallel configuration. A transient simulation model developed in TRNSYS program has been utilised to simulate the thermal performance of the combined ORC-GSHP based microco/trigeneration system. This later supplies heating and cooling to the residential load during the heating mode as required, with the capability to switch to a charging mode, where the ORC unit is directly coupled to the ground heat exchanger (GHE), which operates as a thermal energy storage and provides energy to the GSHP. The feasibility of this combined system configuration as well as its comparison with a conventional GSHP system are investigated for use in residential application in Ottawa, Canada temperature conditions.

Results disclosed that the proposed micro-cogeneration system had the operating hours and performance of the GSHP improved by the addition of the ORC unit, resulting in about 11.8% reduction in hours in the colder city of Ottawa. The COP (coefficient of performance) of the GSHP system sustained a much higher value overall due to the addition of the ORC system to maintain the GHE storage temperature. In terms of net energy reduction between the conventional GSHP system and the ORC-assisted one, results revealed that Ottawa had energy usage reduction of 82.0%, demonstrating that the addition of an ORC to provide heating and recharge the GHE of a GSHP system has many advantages that could be accomplished by the end-user.
An Investigation of the Fuel Economy of a Drive Cycle Developed Using the Road Load Energy Criterion
Authors: Vasquez Peter , Quiros Edwin , Denoga Gerald Jo , Corpus Robert Michael , Lomotan Robert James
Published: July 2021

Efforts to mitigate climate change include lowering of greenhouse gas emissions by reducing fuel consumption in the transport sector. Various vehicle technologies and interventions for better fuel economy eventually require chassis dynamometer testing using drive cycles for validation. As such, the methodology to generate these drive cycles from on-road data should produce drive cycles that closely represent actual on-road driving from the fuel economy standpoint.

This study presents a comparison of the fuel economy measured from a drive cycle developed using road load energy as a major assessment criterion and the actual on-road fuel economy of a 2013 Isuzu Crosswind utility vehicle used in the UV Express transport fleet in Metro Manila, Philippines. In this approach to drive cycle construction from on-road data, the ratio of the total road load energy of the generated drive cycle to that of the on-road trip is made the same ratio as their respective durations. On-road velocity and fuel consumption were recorded as the test vehicle traversed the 42.5 km. Sucat to Lawton route and vice versa in Metro Manila. Gathered data were processed to generate drive cycles using the modified Markov Chain approach. Three drive cycles of decreasing duration, based on the practicality of testing on a chassis dynamometer, were generated using three arbitrary data compression ratios. These drive cycles were tested using the same vehicle on the chassis dynamometer and compared with the on-road data using road load energy, fuel economy, average speed, and maximum acceleration. For the 893-seconds drive cycle generated, the road load energy error was 3.93% and fuel economy difference of 1.14%. For the 774-seconds cycle generated, the road load energy error was 4.34% and fuel economy difference was 0.91%. For the 664-seconds drive cycle, the road load energy error was 3.68% and fuel economy difference was 0.91%. On-road fuel economy for the 42.5-km. route averaged over nine round trips was 8.785 km/L. Based on the results, the road load energy criterion approach of drive cycle construction methodology can generate drive cycles which can very closely estimate on-road fuel economy.
Preliminary Design Development, Laboratory Testing, and Optimization of a 6.6 MW-Thermal All-Refractory Particle Heating Receiver
Authors: Yeung Ryan , Sarfraz Muhammad , Repole Kenzo , Jeter Sheldon , Alswaiyd Abdulelah , Alaqel Shaker , El-Leathy Abdelrahman , Al-Ansary Hany
Published: July 2021

Heat receiver design is an essential portion of Concentrating Solar Power (CSP) plants, particularly within CSP systems that are particle based. Particle based CSP promises higher operating temperatures and more cost-effective thermal energy storage than existing systems. Two general types of Particle Heat Receivers (PHR) are under development, variations of the free-falling curtain concept being developed by Sandia National Labs and an obstructed flow concept being developed by King Saud University (KSU) and Georgia Institute of Technology (GIT)[1, 2]. The obstructed flow design utilizes specifically engineered obstacles placed in the flow path of the particles to remove momentum and kinetic energy and promote lateral and depth-wise mixing. This design is named the discrete structure or DS-PHR. This paper focuses on development and design work that has been done with the existing DS-PHR developed by GIT and KSU. Previous iterations of the DS-PHR have utilized obstruction materials that include simple metal meshes, and ceramic formed into an inverted V-shapes or chevrons. However, these previous designs have some shortfalls. The metallic mesh design has structural integrity issues under intense radiation, inherent in a DS-PHR. The ceramic chevrons have a disadvantageously thick leading edge, which may intercept too much radiation and overheat. Current development has continued with improvements to remedy the issues of the previous design work. Experience, modeling, and testing have shown that a cavity receiver is preferred to reduce heat and particle loss in the system. Recent work has been devoted to developing a Discrete Structure Refractory Particle Heat Receiver (DS-RPHR) suitable for cavity installation working with a north-located field. The simplest suitable configuration is 5 flat ceramic plates, or absorber panels, arranged in an arc, forming a 15° angle of inclination, to improve particle retention in the system. To increase particle residence time, quartz rods are placed onto the back plane of the DS-PHR, in a hexagonal configuration. These serve as the momentum scrubbing obstructions as mentioned above. The performance of this design will be discussed in the following paper. This design has been extensively modeled using NREL’s Soltrace to evaluate thermal and optical performance. Modeling has shown high thermal efficiency in the design, as well as promising heat flux profiles across the receiver. Currently at KSU, a 300 kW-thermal testing facility has been constructed and used for high temperature testing. The final proposed 6.6 MW-thermal design, called the pre-commercial demonstration, will be built at a site owned and operated by Saudi Electric Company, in Waad Al-Shamal, 20 kilometers east of Tuarif, Saudi Arabi.
Least Cost Microgrid Resource Planning for the Natural Energy Laboratory of Hawaii Authority Research Park
Authors: Headley Alexander , Schenkman Benjamin , Olson Keith , Sombardier Laurence
Published: July 2021

The Natural Energy Laboratory of Hawaii Authority’s (NELHA) campus on The Island of Hawai’i supplies resources for a number of renewable energy and aquaculture research projects. There is a growing interest at NELHA to convert the research campus to a 100% renewable, islanded microgrid to improve the resiliency of the campus for critical ocean water pumping loads and to limit the increase in the long-term cost of operations. Currently, the campus has solar array to cover some electricity needs but scaling up this system to fully meet the needs of the entire research campus will require significant changes and careful planning to minimize costs. This study will investigate least-cost solar and energy storage system sizes capable of meeting the needs of the campus.

The campus is split into two major load centers that are electrically isolated and have different amounts of available land for solar installations. The value of adding an electrical transmission line if NELHA converts to a self-contained microgrid is explored by estimating the cost of resources for each load center individually and combined. Energy storage using lithium-ion and hydrogen-based technologies is investigated. For the hydrogen-based storage system, a variable efficiency and fixed efficiency representation of the electrolysis and fuel cell systems are used. Results using these two models show the importance of considering the changing performance of hydrogen systems for sizing algorithms.
Thermal-Economic Optimization of Moving Packed Bed Particle-to-SCO2 Heat Exchanger Using Particle Swarm Optimization
Authors: Zheng Yanjie , Hatzell Kelsey B.
Published: July 2021

Low cost (< $150 kWt−1) and high heat-transfer coefficient particle heat exchangers may enable high temperature operation of high efficiency power cycles (supercritical CO2/air Brayton) [1–3]. Currently, these heat exchangers are cost-prohibitive and require large surface areas due to ineffective particle-particle and particle-CO2 heat transfer. Particle heat transfer media are examples of complex material systems that can display a re-configurable mesostructure during flow or shearing processes. This deformation or rearrangement in the underlying active material can cause a decrease in the thermal transport properties and limit the heat-transfer coefficient. For future adoption, it is critical that we gain a greater understanding of how local (particle-particle) thermophysical properties are affected by system architecture/design. Traditional heat exchanger optimization approaches are limited and often lead to non-feasible design approaches. Here, we employ a stochastic and evolutionary method, particle swarm optimization (PSO), to perform a multi-objective optimization for the particle-to-sCO2 shell-and-plate heat exchanger for two state-of-the-art particulate materials (i.e., Accucast ID50K and CARBO HSP). The objective function for optimization considers the minimum payback period (economics), entropy generation (thermodynamics), and volume (engineering). The results suggest that Accucast ID50K is preferable for a packed bed heat exchanger from the perspective of minimizing payback period and volume, while at a larger entropy generation rate than CARBO HSP.
Investigation of Operation Scheduling Optimization of Multi-Energy System in an Industrial Park With Consideration of Heat Storage
Authors: Zhang Shuting , Lin Xiaojie , Zhong Wei , Liu Sibin
Published: July 2021

Under the background of carbon neutralization, developing the multi-energy system (MES), which effectively integrates kinds of energy resources, is one of the keys to solving the environmental contradiction. At present, considering heat storage, the research on the optimal scheduling of MES, especially industrial park MES, focuses on the heat storage tank. The potential of the heating supply network (HSN) for heat storage is underestimated and its operational constraints haven’t been fully studied. Therefore, with consideration of quantitative heat storage in HSN, a day-ahead operation scheduling optimization model for MES is proposed. The model proposes a tubular heat storage body (THSB) to describe the heat storage characteristics and charge/discharge constraints of HSN and studies its impact on economic benefits and stability of output power. Equivalent method is used to quantify the heat storage capacity of HSN. Based on the established model, we take a real industrial park to optimize the operation plan of heating conditions in winter. Results indicate that the optimized scenario shows better economic benefits and output stability, which saves 1,303 yuan of operation cost per day.
Simulation of a Wet-Surface Bare Rod Heat Exchanger
Authors: Shaik Abdul Raheem , Al-Alili Ali , Alhassan Saeed M.
Published: July 2021

In this paper, a CFD analysis is carried out in ANSYS Fluent to investigate the enhancement of heat transfer and vapor condensation rate in a novel air-to-solid micro bare rod heat exchanger. Literature indicates that the enhancement of heat transfer occurs at the cost of increasing pressure drop across the heat exchanger; due to proximity of the rods. The heat exchanger is first modeled in Engineering Equation Solver (EES) to perform under Abu Dhabi’s hot and humid climate conditions. The heat exchanger is modelled to operate at low Reynolds number to increase the air residue time and allow condensation to occur. In the model, copper rods of diameter 1 mm are evenly spaced out between 2 plates to form the heat exchanger. Fixing the space occupied by the heat exchanger, i.e. volume occupied, the diameter of the copper rods is varied from 0.5 to 5 mm. The effect of the copper rods’ diameter and the spacing between the rods on the rate of vapor condensation, heat transfer, and pressure drop are investigated. Correlations for a micro bare rod heat exchanger exposed to a humid air stream are not available in the literature. Thus, using CFD modeling, the j (dry and wet side) and f factor correlations are determined for this novel heat exchanger operating at low Reynolds numbers. Lastly, the performance of the novel heat exchanger is compared to a fin-tube heat exchanger occupying the same volumetric space operating at the same conditions.
The Impact of COVID-19 on Energy Consumption in the United States: An Overview
Authors: Kahn Lindsey , Najafi Hamidreza
Published: July 2021

Lockdown measures and mobility restrictions implemented to combat the spread of the novel COVID-19 virus have impacted energy consumption patterns, particularly in the United States. A review of available data and literature on the impact of the pandemic on energy consumption is performed to understand the current knowledge on this topic. The overall decline of energy use during lockdown restrictions can best be identified through the analysis of energy consumption by source and end-user breakdown. Using monthly energy consumption data, the total 9-months use between January and September for the years 2015–2020 are calculated for each end-use. The cumulative consumption within these 9 months of the petroleum, natural gas, biomass, and electricity energy by the various end-use sectors are compared to identify a shift in use throughout time with the calculation of the percent change from 2019 to 2020. The analysis shows that the transportation sector experienced the most dramatic decline, having a subsequent impact on the primary energy it uses. A steep decline in the use of petroleum and natural gas by the transportation sector has had an inevitable impact on the emission of carbon dioxide and other air pollutants during the pandemic. Additionally, the most current data for the consumption of electricity by each state and each end-user in the times before and during the pandemic highlights the impact of specific lockdown procedures on energy use. The average total consumption for each state was found for the years 2015–2019. This result is used calculation of yearly growth rate and average annual growth rate in 2020 for each state and end-user. The total average annual growth rate for 2020 was used to find a correlation coefficient between COVID-19 case and death rates as well as population density and lockdown duration. To further examine the relationship a correlation coefficient was calculated between the 2020 average annual growth rate for all sectors and average annual growth rate for each individual end-user.
Performance Study of Thermoelectric Power Generators at Different Geometrical Configurations
Authors: Elsabahy Mohamed M. , Rabie Ramy , Ahmed Mahmoud
Published: July 2021

The thermoelectric generator (TEG) output power is mainly dependent on physical characteristics, dimensions, leg configuration, number of p-n thermocouples, and other parameters. Therefore, identifying the optimal leg configuration that attains the best performance is essential. The present work considers several leg configurations by the volume reduction of the conventional prism leg, without changing the shape class via decreasing basic dimensions (i.e. leg height or cross-sectional area) and with morphing the original prism into X and trapezoidal shapes. A three-dimensional thermo-electric model is developed to investigate the performance of TEG legs at the uni-thermocouple level. Besides, to determine the reliability of the proposed configurations, a wide range of thermal boundary conditions are applied on the hot side to resemble the realistic working environment that TEG might experience at room temperature on the cold side with natural convective cooling. The model is numerically simulated after being validated with the available experimental and numerical data. The comparison indicates that decreasing leg height adversely affects the TEG performance, whereas a significant enhancement in the performance is achieved (in order) for X, trapezoidal and reduced area shapes. However, the performance enhancement, i.e. power and efficiency, associated with the simple reduced area configuration is relatively close to those achieved by X or trapezoidal ones, raising many questions in terms of simplicity and manufacturing cost. The performed research further deepens our understanding of TEG performance enhancement via optimizing legs’ attributes at uni-thermocouple as a single building block of the full-size TEG module.
Preliminary Techno-Economic Optimization Of 1.3 MWe Particle Heating Receiver Based CSP Power Tower Plant for the MENA Region
Authors: Khatti Shakir Shakoor , Jeter Sheldon , Al-Ansary Hany
Published: July 2021

Due to increasing energy demand around the globe and potential environmental impacts of fossil fuels, it has become a crucial task for researchers to find alternatives to generate electricity from low-carbon resources at lower costs. Three types of advanced CSP are under consideration: systems heating salt, gas, or particulate. Particle heating receiver (PHR) based central receiver power tower CSP is an emerging technology that promises higher operating temperatures and more cost-effective thermal energy storage (TES) than feasible with existing or alternative CSP systems. For reasons stated above and others, we propose that the particle heating receiver (PHR) based CSP in the classic central receiver power tower (CRPT) configuration will be the most suitable especially in the promising Middle East and North Africa (MENA) region. Specifically, Duba, Al Wajih, and Wa’ad Al-Shamaal regions in Saudi Arabia have high direct normal irradiation (DNI) and represent potential locations. PHR based CSP power tower plant consists of a central receiver power tower with TES and cavity receiver, heliost at field, a high-temperature solar gas turbine with built-in fuel backup to operate in hybrid mode (using both fuel and solar-thermal resources). This study focuses on the optimization of a solar heat supply system (SHSS), consisting of a tower, cavity receiver, and heliostat field. SolarPILOT – Solar Power tower Integrated Layout and Optimization Tool is a field layout optimization tool developed by National Renewable Energy Laboratory (NREL). SolarPILOT is used in this study to generate the field layout of a 1.3 MWe power plant with a solar multiple (SM) of 2, 3, and 4. Cost models for the tower, receiver, and heliostats are developed using the data from research programs, contractors, manufacturing companies, and general cost engineering data and tools. System Advisor Model (SAM) is further used to simulate the annual performance of CSP tower plant including power block (high-temperature gas turbine) and TES using optical efficiency data from SolarPILOT to optimize PHR-based CSP tower plant. The results of this research are fundamental to the techno-economic analysis (TEA) of this and similar smaller-scale systems and will support the TEA of larger grid-connected and smaller off-grid systems operating independently or in conjunction with PV systems.
A Semi-Empirical Water and Energy Analysis of Industrial Production of Nickel From Mineral Ores: Comparative Analysis Between Two Different Technologies of Calcination
Authors: Ruiz Janneth , Ardila Antonio , Rueda Bernardo , Echeverri Jorge , Quintero Daniel , Corredor Lesme , González Arturo
Published: July 2021

In the ferronickel production process, mineral calcination is one of the most energy-intensive stages. In a typical rotary kiln calciner, particulate solids and combustions gases move counter currently, while solids undergo drying, pre-reduction, and partial reduction reactions. The combustion of natural gas provides the thermal energy for drying and reduction reactions. About 80 to 85% of the incoming laterite ore leaves the reactor as calcined ore, while the flue gases entrain part of the solids as dust. This work presents a theoretical analysis contrasted with experimental results to evaluate the partial reduction of laterite ores in two rotary kilns of 185 m and 135 m length. The study focused on the water formed in the process, including a comparative analysis of water consumption by two different solids recovery technologies, a gas scrubber and an electrostatic precipitator. Simulations allowed evaluating the water and greenhouse gas formation in the main streams of the process. Among the tested operation conditions, the moisture content in the pellets, consisting of agglomerated dust, strongly influenced the amount of water released in the process and the energy consumption. Furnace RK-2 needs approximately 56% more energy to evaporate the moisture content in the feedstock. Furthermore, furnace RK-2 released 55.4 m3h−1 of water into the atmosphere, which represented two times the amount released by furnace RK-1. Gas scrubber analysis showed that as the liquid water increased, more H2O in the gases was condensed; however, the destroyed exergy also increased. Electrostatic precipitators appear as an adequate technology for reducing water and energy consumption in the ferronickel industry.
Development and Testing of a 20 kW Moving Packed-Bed Particle-To-sCO2 Heat Exchanger and Test Facility
Authors: Albrecht Kevin J. , Laubscher Hendrik F. , Carlson Matthew D. , Ho Clifford K.
Published: July 2021

This paper describes the development of a facility for evaluating the performance of small-scale particle-to-sCO2 heat exchangers, which includes an isobaric sCO2 flow loop and an electrically heated particle flow loop. The particle flow loop is capable of delivering up to 60 kW of heat at a temperature of 600 °C and flow rate of 0.4 kg/s. The loop was developed to facilitate long duration off-sun testing of small prototype heat exchangers to produce model validation data at steady-state operating conditions. Lessons learned on instrumentation, control, and system integration from prior testing of larger heat exchangers with solar thermal input were used to guide the design of the test facility. In addition, the development and testing of a novel 20-kWt moving packed-bed particle-to-sCO2 heat exchanger using the integrated flow loops is reported. The prototype heat exchanger implements many novel features for increasing thermal performance and reducing pressure drop which include integral porting of the sCO2 flow, unique bond/braze manufacturing, narrow plate spacing, and pure counter-flow arrangement. The experimental data collected for the prototype heat exchanger was compared to model predictions to verify the sizing, thermal performance, and pressure drop which will be extended to multi-megawatt heat exchanger designs in the future.
Perception of violin soundpost tightness through playing and listening tests
Authors: Fu Lei , Fritz Claudia , Scavone Gary
Published: July 2021

This study involved playing and listening (using recorded sounds) experiments to investigate how changes in soundpost length (for a fixed soundpost position) affect the perceptual qualities of the violin and what the threshold of change is below which players and luthiers do not perceive differences. A length-adjustable carbon fiber soundpost was employed. During the playing experiment, subjects played a provided violin on which the soundpost length was modified by the experimenter to find their optimal soundpost lengths. Then the experimenter varied the soundpost length randomly in ten trials within ±0.11 mm around their optimal lengths and asked subjects to always compare with the previous setting. The results showed that subjects' optimal soundpost lengths varied from 0.132 to 0.616 mm relative to the original length (53 mm), but subjects could not recognize length variation of 0.11 mm or less at above chance levels. During the listening experiment, subjects listened to 16 pairs of recordings through a computer interface and were asked, for each pair, whether the violin setup was the same or different. The results showed that subjects could differentiate soundpost lengths with a difference of about 0.198 mm at better than chance level.
Using machine learning to automate ultrasound-based classification of butt-fused joints in medium-density polyethylene gas pipes
Authors: Shafiei Alavijeh Maryam , Scott Ryan , Seviaryn Fedar , Maev Roman Gr.
Published: July 2021

Polyethylene (PE) pipes are widely used in gas distribution. Their joints are prone to various flaws and are the most problematic part of the pipeline, so the infrastructure industry requires an effective inspection technique. Butt-fusion (BF) is the most common method of joining PE pipes. In this research, we investigated the applicability of machine learning (ML) to automate the ultrasonic inspection of PE pipe BF joints. Flawless and defective joints were fabricated. A-scan signals were collected from each group of samples using a customized chord transducer, with the aim of developing and assessing the viability of ML approaches to the problem of joint classification. We compared several ML approaches to the problem and found that convolutional neural networks were most performant, classifying signals with an F1 score of 0.874 in a four-class problem (identifying defect presence and type) and of 0.912 in binary classification (defect presence/absence only). Our results show that an ultrasonic chord-type transducer approach can effectively resolve flawless samples versus those with coarse contaminants or cold fusions and that an ML approach can be used to effectively assess these ultrasonic signals. Our findings can be used to develop a portable, efficient, user-friendly, and inexpensive device for in-field joint inspections.
Structure of an AMPK complex in an inactive, ATP-bound state
Authors: Yan Yan , Mukherjee Somnath , Harikumar Kaleeckal G. , Strutzenberg Timothy S. , Zhou X. Edward , Suino-Powell Kelly , Xu Ting-Hai , Sheldon Ryan D. , Lamp Jared , Brunzelle Joseph S. , Radziwon Katarzyna , Ellis Abigail , Novick Scott J. , Vega Irving E. , Jones Russell G. , Miller Laurence J. , Xu H. Eric , Griffin Patrick R. , Kossiakoff Anthony A. , Melcher Karsten
Published: July 2021

How to catch a dynamic state

AMP-activated protein kinase (AMPK) is a key sensor of energy status in eukaryotes. Its dynamic structure is regulated by allosteric factors including phosphorylation and binding of nucleotides and metabolites. Yan
et al.
developed conformation-specific antibodies that trap AMPK in a fully inactive state that has experienced a large, domain-level rotation. Biophysical experiments in cells and in vitro are consistent with the structural work and support a model in which the activation loop is fully exposed in the completely inactive, dephosphorylated state. These structures inform our understanding of the complex allosteric behavior in this crucial metabolic regulator.

Science
, abe7565, this issue p.
413
Atomically resolved single-molecule triplet quenching
Authors: Peng Jinbo , Sokolov Sophia , Hernangómez-Pérez Daniel , Evers Ferdinand , Gross Leo , Lupton John M. , Repp Jascha
Published: July 2021

Triplet-state lifetime quenched by oxygen

Little is known about the atomistic mechanism that nature uses to mitigate the destructive interaction of triplet-excited pigment chromophores with omnipresent oxygen. Peng
et al.
tackled this challenge by developing a technique based on conducting atomic force microscopy to populate and track triplets in a single pentacene molecule, a model ϖ-conjugated system, placed on a sodium chloride surface (see the Perspective by Li and Jiang). The authors show how the triplet-state lifetime can be quenched in controllable manner by atomic-scale manipulations with oxygen co-adsorbed in close vicinity. The presented single-molecule spectroscopy paves the way for further atomically resolved studies of triplet excited states that play an important role in many other fields, such as organic electronics, photocatalysis, and photodynamic therapy.

Science
, abh1155, this issue p.
452
; see also abj5860, p.
392
Inhibited nonradiative decay at all exciton densities in monolayer semiconductors
Authors: Kim Hyungjin , Uddin Shiekh Zia , Higashitarumizu Naoki , Rabani Eran , Javey Ali
Published: July 2021

Straining for high photoluminescence

The photoluminescence quantum yield in monolayer transition metal dichalcogenides generally drops at high emission intensities because the excitons undergo nonradiative annihilation. Kim
et al.
show that this process is resonantly amplified in these materials by van Hove singularities in their joint density of states. However, application of small mechanical strains (∼0.5%) shifted the van Hove singularities and suppressed the nonradiative processes. Near-unity photoluminescence quantum yield at high exciton densities was seen in exfoliated monolayers of molybdenum sulfide, tungsten sulfide, and tungsten selenide, as well as centimeter-scale tungsten sulfide monolayers grown by chemical vapor deposition.

Science
, abi9193, this issue p.
448
Spatiotemporal invasion dynamics of SARS-CoV-2 lineage B.1.1.7 emergence
Authors: Kraemer Moritz U. G. , Hill Verity , Ruis Christopher , Dellicour Simon , Bajaj Sumali , McCrone John T. , Baele Guy , Parag Kris V. , Battle Anya Lindström , Gutierrez Bernardo , Jackson Ben , Colquhoun Rachel , O’Toole Áine , Klein Brennan , Vespignani Alessandro ,   COVID-19 Genomics UK (COG-UK) Consortium‡, Volz Erik , Faria Nuno R. , Aanensen David M. , Loman Nicholas J. , du Plessis Louis , Cauchemez Simon , Rambaut Andrew , Scarpino Samuel V. , Pybus Oliver G.
Published: July 2021

Fueling outbreaks

The B.1.1.7 lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused fast-spreading outbreaks globally. Intrinsically, this variant has greater transmissibility than its predecessors, but this capacity has been amplified in some circumstances to tragic effect by a combination of human behavior and local immunity. What are the extrinsic factors that help or hinder the rapid dissemination of variants? Kraemer
et al
. explored the invasion dynamics of B.1.1.7. in fine detail, from its location of origin in Kent, UK, to its heterogenous spread around the country. A combination of mobile phone and virus data including more than 17,000 genomes shows how distinct phases of dispersal were related to intensity of mobility and the timing of lockdowns. As the local outbreaks grew, importation from the London source area became less important. Had B.1.1.7. emerged at a slightly different time of year, its impact might have been different. —CA
Chromosome-Level Genome Sequence of the Black Koji Fungus Aspergillus luchuensis RIB2601
Authors: Mori Kazuki , Kadooka Chihiro , Nishitani Atsushi , Okutsu Kayu , Yoshizaki Yumiko , Takamine Kazunori , Tashiro Kosuke , Goto Masatoshi , Tamaki Hisanori , Futagami Taiki
Published: July 2021

Aspergillus luchuensis
is used for the production of awamori and shochu, which are traditional Japanese distilled alcoholic beverages. Here, we determined the chromosome-level genome sequence of
A. luchuensis
RIB2601.