bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying Part-to-Part Flow Variations and Cooling Effectiveness in Engine-Run Blades
Authors: McCormack Kelsey E. , Gailey Nicholas L. , Berdanier Reid A. , Barringer Michael D. , Thole Karen A.
Published: September 2023

As turbine inlet temperatures continue to increase for modern gas turbine engines, the lifing of hot section components operating in a range of environments is becoming increasingly challenging. Engine operations in harsh environments can cause a reduction in cooling capability leading to reduced blade life relative to existing experience. This study analyzes the effects of harsh environments on the deterioration of blade flow and cooling effectiveness in turbine blades by comparing three commercially operated engines with varied operational times referenced against a baseline blade. Spatially resolved surface temperatures measured using infrared thermography at high-speed rotating conditions were evaluated to determine variations in cooling effectiveness as a function of engine operation and blade-to-blade variability from the different commercial applications. Engine-run blades were found to have reduced flow as well as greater part-to-part variation when compared to baseline blades. Blade surface temperature measurements on the deteriorated operational blades indicated film cooling traces dissipated closer to the hole exit relative to baseline blades. Furthermore, the cooling effectiveness varied significantly even between blades from the same engines. The reduction in cooling effectiveness in the engine-run blades led to higher blade temperatures and significantly shorter component life, with some exhibiting as much as an 18% reduction in life compared to baseline blades. This knowledge allows lifing models to be developed toward predicting blade operational effects in harsh environments.
A Multiple-Burner Approach to Passive Control of Multiple Longitudinal Acoustic Instabilities in Combustors
Authors: Sultanpur Supreeth S. , Chakravarthy Satyanarayanan R.
Published: September 2023

Presently, passive methods of controlling combustion instability fall short when one considers stabilizing multiple acoustic modes. In this paper, we present a passive control approach based on the locations of the burners to stabilize multiple acoustic modes. The approach is demonstrated using linear stability analysis performed on a canonical open–open rectangular tube enclosing a flame. A linear flame model based on the kinematic description of the flame surface is used. A simultaneous solution method, as opposed to a segregated method, is developed to calculate the mean flow and to evaluate mode shapes and eigenvalues. The stability analysis is performed both on single and on multiple-burner combustors. In the latter case, the axial and transversal arrangement of burners considered preserves the net volumetric heat release rate and exit temperature. The problem of stabilizing the first three acoustic modes is cast as a multi-objective optimization problem for both types of combustors using the location(s) of the burner(s) as decision variable(s). We show that the use of multiple burners markedly increases the stability of the first three modes while not disturbing the combustor design parameters.
Enhancing Thermal Resistance of Building Walls by Utilizing Fluid Flow in Microchannel Within the Wall
Authors: Shafiee Shahin , Dicko Hamed
Published: September 2023

Microchannels were initially developed for cooling electronic systems. But this innovative system can also be deployed for enhancing thermal resistance of building walls, where they can substitute conventional insulations in building envelop that include the use of certain materials such as wool, polystyrene, wood fiber, cotton denim, etc. This article presents the modelling and simulation results on performance of microchannels in a typical building wall to provide dynamic thermal resistance for the building envelop. The simulations are performed for aluminum microchannels with air and water as working fluids to compare the performance of the system when different fluids are utilized. The microchannels are of rectangular profile and kept with the same geometry for all different cases. Also, to ensure that the simulations are performed under laminar regime for both working fluids, the Reynolds number was maintained between 100 and 900 for different runs. The simulation and analysis results show that microchannels can be used in building envelop to provide dynamic thermal resistance and increase the energy efficiency in different buildings. The results also show that flow of a water-based fluid in microchannels has better heat transfer and heat sinking capabilities as compared to the flow of an air-based fluid.
Fabrication, Modeling, and Testing of a Prototype for Particle Thermal Energy Storage Containment
Authors: Gifford Jeffrey , Davenport Patrick , Wang Xingchao , Ma Zhiwen
Published: September 2023

Increasing penetration of variable renewable energy resources requires the deployment of energy storage at a range of durations. Long-duration energy storage (LDES) technologies will fulfill the need to firm variable renewable energy resource output throughout the year. Conventional electrochemical batteries (e.g., lithium-ion) are uneconomical in this role due to high energy capacity costs. Thermal energy storage (TES) is one promising technology for LDES applications because of its siting flexibility and ease of scaling. Particle-based TES systems use low-cost solid particles that have higher temperature limits than the molten salts used in traditional concentrated solar power systems. A key component in particle-based TES systems is the containment silo for the high-temperature (> 1100 °C) particles. This study combined experimental testing and computational modeling methods to design and characterize the performance of a particle containment silo for LDES applications.

A containment silo prototype was built at a laboratory scale and used to validate a congruent transient finite element analysis (FEA) model. The validation compared the actual and predicted temperature profile through the prototype over six days as the particles cooled from their initial temperature. The performance of a commercial scale (> 5 GWhth) was then characterized using the validated model. The transient FEA model was subject to several charge-discharge cycles to mimic a possible operating schedule. The commercial-scale model predicted a storage efficiency in excess of 95% after five days of storage with a design storage temperature of 1200 °C. Insulation material and concrete temperature limits were considered as well. The validation of the methodology means the FEA model can simulate a range of scenarios for future applications. This work supports the development of a promising LDES technology with implications for grid-scale electrical energy storage, but also for thermal energy storage for industrial process heating applications.
A Transdisciplinary Approach and Design-Thinking Methodology for Energy Transition
Authors: Ozsoy Canan M. , Mengüç M. Pinar
Published: September 2023

The World is facing a climate crisis today. Since it is primarily due to the emissions from the use of fossil fuels, we must re-think and re-act on how we generate, transmit, distribute, and consume energy in industry, buildings, and transportation. Development of creative solutions and strategies to decrease emissions requires an energy transition framework and should involve every person, company, entity, and all governments. Such a framework can only be achieved with efforts at both local and global scales, which needs to convince (a) industries to change their traditional operation modalities, (b) people to alter their consumption behaviors, and (c) governments to change their rules, regulations, and incentives. The complexity and the magnitude of this enormous task demand coordination and collaboration of all stakeholders, besides the need for technological innovations.

In this paper, we outline a transdisciplinary approach and design-thinking methodology (TADTM) to tackle this challenging task. Our premise is that such complex problems need a fundamental understanding of not only engineering solutions but also those for business operations, financing, socio-economic governance, legislation, and regulations. Also, these problems need to be considered by different decision-makers with seamless interactions and structured teamwork. Towards this, we emphasize the need for a solid transdisciplinary framework for industrial corporations to change their energy policies with the help of either/both practical and doable energy efficiency measures and using renewable/alternative energy in their operations.
Energy Analysis of a Solar-Powered Heating System for a Greenhouse in the Martian Environment
Authors: Madhusudhan Nivedha Karigiri , Najafi Hamidreza
Published: September 2023

Greenhouses are considered critical platforms for developing sustainable living conditions for extraterrestrial environments. The extreme environmental conditions as well as the limitations in energy sources lead to major challenges is the development of proper environments for plant growth in support of manned planetary space missions. The present paper is focused on developing a mathematical model to perform an energy analysis on the heating requirements for a greenhouse in the Martian environment. The extreme cold temperatures and lower amount of solar radiation, as compared to Earth, necessitate the use of the proper heating system for greenhouse in the Martian environment. Energy scarcity, on the other hand, is a crucial factor that must be considered for supplying the heating system in an extra-terrestrial environment. For this study, weather data are obtained from Rover Environmental Monitoring System on board the Curiosity Rover, located near the Gale crater. Using the daily minimum and daily maximum temperature values recorded, a model is developed and the heating load calculation for a greenhouse with a fixed geometry is performed. The amount of energy needed to address the annual heating demands is determined. The available solar radiation for solar power generation using photovoltaic panels for a period of one Martian year (668 Sols) is also evaluated. Several atmospheric parameters are taken into consideration, and the seasonal variations of solar irradiance are studied. The size of a solar photovoltaic array for addressing the energy demands of the heating system is calculated accordingly. Several other parameters including solar panel efficiency, solar cell temperature based on the ambient conditions and wind velocity and the effects of extreme temperature conditions on solar cell degradation are discussed. The results from this study can be used to help with addressing the potential challenges to support sustainable living conditions in extra-terrestrial environmental conditions.
Multi-Objective Optimization of Distributed Energy Systems Considering Time-of-Use Pricing Impacts
Authors: Maharjan Krisha , Zhang Jian , Cho Heejin , Chen Yang
Published: September 2023

Distributed energy systems (DES) have been considered as a promising solution due to the benefits on efficiency and environment sides. However, despite the rapid development of distributed energy resources and technologies, the share of the distributed energy generation is still small in comparison to that of traditional generation. Time-of-use (TOU) pricing can be an important incentive strategy to encourage the penetration of distributed energy systems. In this paper, a multi-objective optimization considering the time-of-use pricing impacts is proposed to determine the optimal configuration and capacity of distributed energy system involving different technologies including solar photovoltaic (PV), solar thermal collector (STC), combined heating and power system (CHP), and integrated energy storage (ES). The distributed energy system is designed to satisfy the electric and thermal load of commercial buildings (large hotel and medium office) partially or entirely. The proposed multi-objective optimization is utilized to configurate the optimal combination of distributed energy technologies as well as the system capacity to reduce both the cost and environment impact of the system in different locations. Results show that the proposed optimization method can achieve a tradeoff between system cost and environment impact based on the existing time-of-use pricing structure.
Steady State Modeling of a Regenerative Rankine Cycle for the Natrium System
Authors: Meek Aiden S. , Dana Seth J. , Bryan Jacob , Basnet Manjur , Wang Hailei
Published: September 2023

With increasing penetration of renewable energy and the challenges that come with it, advanced nuclear energy systems will play an instrumental role for society to reach the goal of carbon-free power in the coming decades. Recently, an advanced nuclear power plant design (Natrium™), a sodium fast reactor with thermal energy storage, is slated to be deployed towards the end of this decade. With 5.5 hours of molten salt energy storage, the Natrium system will complement renewables and ease the intermittency challenges associated with solar and wind energy. In this work, a steady-state model of the Natrium system is modeled and optimized for efficiency. This model not only provides the state points within the regenerative Rankine cycle but also provides initial values for the variables of a dynamic system model in parallel development. With the molten salt storage temperature set by the sodium fast reactor (550 °C), the degree of superheat of the steam and its pressure for the regenerative Rankine cycle are determined. The states and mass fractions (turbine bleeding ratios) of the three regenerators are determined through optimization for maximum thermal efficiency. With the optimized cycle design, the model predicts 40% thermal efficiency. The model also checks to ensure no second law of thermodynamics violation for the regenerators. While high effectiveness is desired for regeneration (to maximize thermal efficiency), the physical sizes of the regenerators must be reasonably sized, to keep the cost managable. The heat exchanger sizes (area) are determined using ε-NTU method.
An Optimization Study of CO2 Heat Pump Water Heaters Using NSGA-II
Authors: Soleimani Shima , Schaefer Laura , Liaqat Kashif , Cole Aaron , Temming Jörg , Kösters Heiner
Published: September 2023

Due to growing concerns about the environmental impact of refrigerants, CO2 heat pumps have been increasingly evaluated as efficient alternatives for conventional heat pumps. Performance analyses of CO2 heat pump water heaters (HPWHs) have been the subjects of many studies, but these are typically limited to parametric analyses of air-source heat pumps. The interrelated behavior of the supercritical and subcritical thermodynamic properties, component operation, and efficiency means that a parametric study cannot adequately capture the inherent nonlinearity. Therefore, this paper, for the first time, aims to perform a multi-objective optimization on water-sourced HPWH performance in order to minimize the total component costs, maximize gas cooler (GC) heating capacity, and maximize the coefficient of performance (COP) using two different optimization scenarios. The decision variables are defined as GC pressure (75 to 140 bar), evaporator temperature (−19.5 to 0.2°C), and GC outlet temperature for CO2 (16 to 36°C). The model performance is constrained by the practical ranges of the GC and evaporator inlet and outlet temperatures for water. A coupled simulation-optimization model through Python is developed using Engineering Equation Solver (EES) software and the non-dominated sorting genetic algorithm II (NSGA-II). The result of the optimal Pareto front showed that the optimal GC heating capacity changes from 19.2 to 56.7 kW, with a lowest cost of $7,771 to a highest cost of $9,742, respectively. When the lower bound of the GC outlet temperature was set to 32°C, the Pareto front showed a maximum COP of 3.23, with a corresponding GC heating capacity of 44.36 kW.
Impact of Temperature and Ethanol Concentration on High Temperature Direct Ethanol-Based Proton Exchange Membrane Fuel Cell
Authors: Chowdhury Prantik Roy , Gladen Adam C.
Published: September 2023

This study examines the effect of cell temperatures and ethanol concentrations on the performance of a high temperature based direct-ethanol proton exchange membrane (PEM) fuel cell. A series of experiments were conducted at different combination of temperature (150 °C and 165 °C) and ethanol concentration (1 mol/L, 3 mol/L, 6 mol/L, and 9 mol/L) with an ethanol and air flow rate of 2 ml/min and 2 L/min, respectively. The resulting polarization and power curves show the overall effect of temperature and ethanol concentration on the cell performance. A two-factor analysis has been performed to investigate the main effect and interactions of temperature and concentration on maximum power and cell current at 0.2 V and 0.4 V. Result shows that the increase of cell temperature from 150 °C to 165 °C causes a significant improvement of cell potential and power output. At 165 °C, low concentration of ethanol (1mol/L) provides good power output until 150 mA/cm2, intermediate concentration (3 mol/L) gives high power output and allows for operation at high current density. It (3 mol/L) amplifies the effect of temperature at maximum power operation. Higher concentration causes the significant drop of cell performance. Therefore, the fuel cell operating condition of 3 mol/L and 165 °C provides balancing of ethanol and water molecules in the catalyst active side and gives the highest cell potential and power output.
Construction and Validation of a Pumped Loop Cycle for Characterizing Heat Transfer of Refrigerants and Alcohols Near Supercritical Points
Authors: Pepper Benjamin , Meek Aiden , Ghorbani Mahdi , Wang Hailei
Published: September 2023

A clear understanding of heat transfer in fluid flow is often analyzed via heat input through a channel which has been thoroughly validated. Common refrigerants and light alcohols possess intrinsic heat transfer properties at supercritical conditions that are desirable for low- and mid-temperature sourced power cycles. In this experiment, heat transfer characteristics of novel fluids applied to a supercritical power cycle are controlled and analyzed in a pumped loop system. The controlled test section heat exchanger in designed in two phases: alpha design phase for initial validation of the test apparatus with non-corrosive fluids; and a beta design for tests of corrosive/hazardous fluids with improved high-pressure capability. The test section provides heat input to the fluid through discrete heat pipes that allow for the continuous measurement of heat transfer properties of local fluid packets along the length of the heat exchanger. Performance and heat transfer measures from the system are compared to similar experiments in the literature to validate the methodology. The system demonstrates the ability to isolate heat transfer properties of fluids in the pseudocritical region and their transitions. This experiment guides the design for further study of fluids of interest.
Hot-Zone Design of Carbon/Carbon-Metal Sandwich Structure Composite Using CVI/CVD Material Processing
Authors: Huang Xiaoqing , Zhang Hui
Published: September 2023

The sandwich structure is a composite structure that is widely used in aviation, construction, and other fields due to its superior performance. We have designed a vertical dual-temperature-zone-dual-channel chemical vapor infiltration/deposition system that includes a deposition zone and a preheating zone. Carbon fiber-reinforced matrix carbon composites are used as the inner and outer panels of the sandwich structural materials, while structurally designed metal grids are proposed as the core material. We establish flow, heat and mass transfer, and chemical reaction models to carry out optimal control of densification and the hot zone in the carbon/carbon-metal sandwich structure composite using numerical simulation methods. We use a single control variable approach, such as changing the mesh spacer size, heater temperature and length, and core-to-plate ratio, to explore the effects of different design parameters on the hot zone and densification of the carbon/carbon-metal sandwich structure composite. The results show that optimizing the heater power, the distribution of the metal grid, and other parameters can lead to lower Damkhler numbers. Consequently, higher axial temperature gradients and lower radial temperature gradients can be achieved during the densification process.
Understanding Saline Water Droplet-Membrane Surface Interaction Using Molecular Dynamics Simulations
Authors: El Kadi Khadije , Ali Mohamed I. Hassan , Islam MD Didarul , Janajreh Isam
Published: September 2023

In this work, we utilize molecular dynamics (MD) simulations to investigate the interfacial characteristics of water droplet on a membrane surface. The MD approach allows us to probe the system dynamics and identify the fundamental mechanisms that govern the surface interactions at various conditions. Through simulating the droplet deposition process at thermodynamic equilibrium, we gain a comprehensive understanding of the interactions between the water droplet and the membrane surface at the atomic level. At different levels of water droplet salinity, results showed the strong influence of droplet salinity on surface tension and thus on wettability. Specifically, increasing salt concentration to brine water level was found to increase both droplet contact angle and droplet height by 49% and 62%, respectively, indicating reduced surface hydrophilicity. These simulations provide valuable insight into the complex interactions of multicomponent water mixtures, with potential implications in the fields of membrane technology and water purification.
Thermal Conductivity Extraction From Frequency Domain Thermo-Reflectance Experiments Using the Phonon Boltzmann Transport Equation
Authors: Saurav Siddharth , Mazumder Sandip
Published: September 2023

The Boltzmann Transport Equation (BTE) for phonons was solved numerically in cylindrical coordinates and in time domain to simulate a Frequency Domain Thermo-Reflectance (FDTR) experimental setup. The phase lag between the pump and probe signals was computed for a pump laser modulation frequency ranging from 20–200 MHz. Results were obtained both with and without the inclusion of optical phonons, as well as with two different relaxation time-scale expressions (Holland versus Broido) obtained from the literature for silicon. It was found that inclusion of optical phonons significantly improved the agreement between the measured and the computed phase lag, while a clear superiority of one relaxation time-scale expression over the other could not be established. Subsequently, the thermal conductivity was extracted by fitting the Fourier heat conduction equation results — also solved numerically in time domain — to the measured and computed (using BTE) phase lag values. The BTE predictions resulted in thermal conductivity values that are slightly closer to the bulk value (smaller thermal conductivity suppression) than what the experimental data suggested.
Numerical Study of Thermal Management Systems Using Phase Change Materials Integrated With Heat Sink for Wireless Super-Fast Charging Stations of EVs in Constant Heat Flux Condition
Authors: Ghorbani Mahdi , Wang Hailei , Roberts Nicholas
Published: September 2023

With growing electrification of light-duty vehicles, fast and super-fast (or high-power) charging stations for electric vehicles will be instrumental to continue enabling this transformation. In addition to plug-in charging, high-power wireless charging has been attracting increasing attention and interests. Despite the fact that wireless super-fast charger is highly efficient (above 90%), the amount of wasted energy it releases is still considerable. For instance, for a 1MW wireless charger under investigation, the expected heat dissipation rate will be minimum of 50 kW. Meanwhile, due to the compactness of these power electronics, the resultant heat flux (i.e., 25 kW/m2) will be challenging for conventional air-cooling solutions. In this study, thermal management of wireless supercharger module of electrical vehicle using a finned base heat sink integrated with Phase Change Material (PCM) has been investigated. Specifically, paraffin RT70 has been numerically investigated to study its feasibility as the desired PCM. A 2D model of the PCM domain has been developed in ANSYS Fluent, followed by simulations under high heat flux condition (i.e., 25 kW/m2). Given control of the junction temperature of power electronics is crucial to keep the system working efficiently and reliably, alternative PCMs and conduction enhancement techniques using different finned base heat sink configurations have been applied to achieve improved thermal management performance. Meanwhile, the effect of using PCM with different thermal conductivity has been studied to have a better understanding of its effect on the efficiency of thermal management system. In the end, a PCM-based heat sink will be introduced to maintain the junction temperature below 80 °C in charging time of 35 minutes.
Heat Transfer Workshops Using the Personal Engineering Platform
Authors: Diller Thomas , Bairaktarova Diana
Published: September 2023

For the past six years the Personal Engineering Platform (PEP) has been used by students in the ME Heat and Mass Transfer course at Virginia Tech to perform hands-on workshops. The PEP is a data acquisition system (DAQ) with an array of sensors and simple equipment designed for each student to perform workshops at home, in the same format as standard homework problems. The system uses a small microcomputer capable of reading at least 3 channels of heat flux sensor and temperature data with a real time display. The total cost is low enough ($200) to justify each student having their own system. There are currently fourteen workshops available covering fundamental topics in conduction, convection, and radiation. The PEP gives each individual student exploratory laboratory experiences to understand real world thermal events outside the confines and expense of the usual University lab. Specific examples are demonstrated and discussed.

To quantify the educational benefits of this program, feedback was obtained from student performance on concept questions and problem solutions, as well as student surveys. At this point over one thousand students have used the system with statistically significant improvement in performance and motivation. It’s been shown to excite the students for further work on thermal design projects and graduate school.
Thermal and Hydrodynamic Behavior of Metal Foams: Contrasting Compressed and Uncompressed Foams
Authors: Nanda Chaitanya Prasad , Zlatinov Metodi , Manglik Raj M.
Published: September 2023

The influence of complex pore structure, their characteristic length, and the contrast between compressed and uncompressed foam structures in forced-convective behavior are explored experimentally. Data for air flows (Pr - 0.71; 300 ≤ Re ≤ 10,000) are presented to highlight the relative performance behavior of uncompressed foams vis-a-vis compressed metal foams. Moreover, a critical issue of the appropriate definition of the hydraulic diameter, especially with foams of different ppi and different compressions, is addressed. Instead of the usual characterization as the square root of permeability, fin theory is applied to consider the void volume of the foam structure, which is mapped with precision using micro-CT scans of the foam cores. The veracity of defining the hydraulic diameter as (4*Vv/Aw) is supported by results for different uncompressed and compressed foam cores made of aluminum that further underscore the influence of foam structure. Although local heat transfer coefficients deteriorate somewhat with smaller pore size and compression, the increased surface area of high PPI compressed foam nevertheless more than compensates and results in a net benefit in thermal performance – 40 PPI 3x compressed foams have 2.5x the effective heat transfer compared to 10 PPI uncompressed foam, and 80% better than 40 fins per inch plane fins and the latter also incur much higher pressure drop penalty. The influence of foam structure and their degree of compression on the thermal-hydrodynamic performance are also delineated, and these results provide uniquely nuanced insights in characterizing enhanced heat transfer by applying fin theory to metal foams.
Numerical Investigation of the Thrust Vectoring Performance of a Bypass Dual Throat Nozzle
Authors: Afridi Saadia , Khan Tariq Amin , Li Wei , Sherif S. A.
Published: September 2023

Aircraft propulsion systems have become progressively complex due to a recent emphasis on the maneuverability of future fighter aircraft. These systems are capable of providing additional maneuverability to the aircraft. In addition to being able to withstand the high temperatures and pressures generated by modern engines, the systems are also designed to meet the thrust vectoring requirements of various military aircraft. Thrust vectoring (TV) technology allows the nozzle to deflect the primary flow direction to improve the aircraft’s maneuverability. In this study, we analyze the flow characteristics and performance parameters of the bypass dual throat nozzle (BDTN) by varying the bypass angle for a range of nozzle pressure ratios (NPRs). A CFD analysis is carried out using ANSYS FLUENT with the Renormalization Group (RNG) turbulence model to capture the significance of under-expanded and over-expanded jets. The bypass angle varies from 35° to 90° for NPRs ranging from 3∼10. Results show that by decreasing the bypass angle from 90° to 35°, there is a 6% increase in the vectoring angle and an 18% increase in the vectoring efficiency.
Single Phase Immersion Cooling for Hyper Scale Data Centers: Challenges and Opportunities
Authors: Agonafer Dereje , Bansode Pratik , Saini Satyam , Gullbrand Jessica , Gupta Ashish
Published: September 2023

Rapidly expanding computing, storage, and networking requirements have increased the quantity and energy density of modern data centers. Air-cooled high-performance servers often require low air-supply temperatures as well as high air-flow rates, making air-cooling inefficient above certain thermal design power levels. Single-phase liquid immersion cooling (Sp-LIC) addresses this challenge by providing a much higher thermal mass and a high percentage of heat dissipation owing to the direct contact of dielectric fluids with all powered components in the server. It also improves reliability by shielding the ITE from pollutants and hostile environments, and it lowers OpEx by eliminating fans and computer room air handling units. Unlike direct-to-chip liquid cooling, Sp-LIC does not need a complex liquid distribution manifold design as the dielectric liquid can be in direct contact with all components of a server, making it an ideal choice for hyper-scale, edge, and modular data center applications. There are some unique thermal challenges to implementing Sp-LIC such as determining whether to use natural or forced convection and customizing heat sinks that were designed for air-cooling that need to be optimized for dielectric fluids with higher fin efficiency and component reliability (active and passive), which must be addressed and thoroughly researched. These challenges can be addressed using CFD simulations including “Multi Design Variables” and “Multi-Objective Function” Optimization with “Constraints” to help in the design of appropriate extended surfaces and cooling approaches. Experiments are done to verify the CFD models for inlet temperatures greater than 40°C. Also, there are very limited studies related to the reliability of such cooling technology. The accelerated thermal cycling (ATC) test given by ATC JEDEC is relevant just for air cooling but there is no such standard for immersion cooling. The ASTM benchmark D3455 with some appropriate adjustments was adopted to test the material compatibility because of the air and dielectric fluid differences in the heat capacitance property and corresponding ramp rate during thermal cycling. Material characterization findings such as modulus, CTE, creep, fracture toughness, elastic modulus, stress relaxation, cracking, dislocation nucleation, and the viscoelastic properties of the samples will be compared before and after immersion using a TI-980 Nano-indenter, Dynamic Mechanical Analyzer (DMA), Thermomechanical Analyzer (TMA), and Scanning Electron Microscopy (SEM). In all, a comprehensive guide to Sp-LIC for the thermal management of hyper-scale data centers will be presented.
Development of corneal contact lens materials and current clinical application of contact lenses: A review
Authors: Yuan Weichen , Zhao Fangkun , Liu Xiaoyu , Xu Jun
Published: September 2023

Unlike conventional glasses, corneal contact lenses (CLs) can directly contact the surface of the tear film through the application of biopolymer materials, to achieve therapeutic and cosmetic purposes. Since the advent of polymethylmethacrylate, a material that has gained widespread use and attention, statistically, there are now more than 150 × 106 people around the world who wear corneal contact lenses. However, the associated complications caused by the interaction of contact lenses with the ocular surface, tear film, endogenous and environmental microorganisms, and components of the solution affect nearly one-third of the wearer population. The application of corneal contact lenses in correcting vision and myopia control has been widely recognized. With the development of related materials, corneal contact lenses are applied to the treatment of ocular surface diseases, including corneal bandage lenses, drug-loaded corneal contact lenses, biosensors, and other new products, while minimizing the side effects associated with CL wear. This paper summarized the development history and material properties of CLs, focused on the current main clinical applications and mechanisms, as well as clarified the possible complications in wearing therapeutic contact lenses and the direction for improvement in the future.
High-efficiency metalenses for zone-plate-array lithography
Authors: Smith Henry I. , Mondol Mark , Zhang Feng , Savas Timothy , Walsh Michael
Published: September 2023

To date, zone-plate-array lithography has employed an array of binary pi-phase zone plates, each 135 μm in diameter, operating at 405 nm wavelength, in conjunction with a spatial-light modulator and a moving stage, to expose large-area patterns in photoresist without a mask. Although the low focal efficiency (<34%) and high background (>66%) of such zone plates can be mitigated via proximity-effect correction, increased focal efficiency would enable higher quality patterning. To that end, we have designed flat, diffractive-optical “metalenses.” Each is first divided into Fresnel zones, across which the effective index-of-refraction is modulated by forming appropriate pillars or holes such that diffracted beams interfere constructively at the focal spot, located 100 μm in front of the lens plane. The diffraction efficiency of each zone is simulated using rigorous-coupled-wave analysis. A genetic algorithm is then used to determine if higher efficiency can be achieved by repositioning of the pillars or modifying their widths. MEEP software is used to predict focal efficiency of the completed metalens design. Scanning-electron-beam lithography was used to fabricate effective-index-modulated metalenses in CSAR-62 e-beam resist. In some cases, the focal properties and efficiencies of such structures were measured, yielding focal efficiencies up to 54%. In other cases, the e-beam-written pattern was transferred into a spin-on hard mask and then into an organic dielectric of 1.9 index of refraction using reactive ion etching. Focal efficiencies up to 69% are predicted for such structures, a significant improvement over the binary pi-phase zone plates used previously.
Does Prophylactic Stretching Reduce the Occurrence of Exercise-Associated Muscle Cramping? A Critically Appraised Topic
Authors: Evers-Smith John W. , Miller Kevin C.
Published: September 2023

Clinical Scenario: Exercise-associated muscle cramps (EAMC) are sudden, painful, and involuntary contractions of skeletal muscles during or after physical activity. The best treatment for EAMC is gentle static stretching until abatement. Stretching is theorized to relieve EAMC by normalizing alpha motor neuron control, specifically by increasing Golgi tendon organ activity, and physically separating contractile proteins. However, it is unclear if stretching or flexibility training prevents EAMC via the same mechanisms. Despite this, many clinicians believe prophylactic stretching prevents EAMC occurrence. Clinical Question: Do athletes who experience EAMC during athletic activities perform less prophylactic stretching or flexibility training than athletes who do not develop EAMC during competitions? Summary of Key Findings: In 3 cohort studies and 1 case-control study, greater preevent muscle flexibility, stretching, or flexibility training (ie, duration, frequency) was not predictive of who developed EAMC during competition. In one study, athletes who developed EAMC actually stretched more often and 9 times longer (9.8 [23.8] min/wk) than noncrampers (1.1 [2.5] min/wk). Clinical Bottom Line: There is minimal evidence that the frequency or duration of prophylactic stretching or flexibility training predicts which athletes developed EAMC during competition. To more effectively prevent EAMC, clinicians should identify athletes’ unique intrinsic and extrinsic risk factors and target those risk factors with interventions. Strength of Recommendation: Minimal evidence from 3 prospective cohort studies and 1 case-control study (mostly level 3 studies) that suggests prophylactic stretching or flexibility training can predict which athletes develop EAMC during athletic competitions.
Spanish Cross-Cultural Adaptation and Validation of the Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow Score
Authors: Bailón-Cerezo Javier , La Touche Roy , Sánchez-Sánchez Beatriz , de la Rosa-Díaz Irene , Torres-Lacomba María , Hernández-Sánchez Sergio
Published: September 2023

Context: There are no available questionnaires in Spanish that assess the function and performance of shoulder and elbow in overhead sports. The Kerlan-Jobe Orthopaedic Clinic (KJOC) score is a reference tool for this purpose. We aimed to cross-culturally adapt and investigate its measurement properties in Spanish overhead athletes. Design: Cross-cultural adaptation followed the steps of direct translation, back translation, comprehensibility analysis, and review by the Committee of Experts. Then, symptomatic and asymptomatic overhead athletes were invited to complete an electronic version of the Spanish adaptation (KJOC-Sp). The structural validity was evaluated through an exploratory factor analysis with principal axis factoring. Hypotheses were tested for known-groups and convergent validity, studying the correlation with the Shoulder Pain and Disability Index and the Disabilities of the Arm, Shoulder, and Hand Sports Module questionnaires in symptomatic athletes. Cronbach alpha was calculated for internal consistency and intraclass correlation coefficient (ICC)2,1 for test–retest reliability. Floor and ceiling effects and time to completion were also calculated. Results: The KJOC-Sp maintained the content of the original version and was adapted to the new population. One hundred participants (41 females and 59 males) with a mean age of 22.4 (5.9) years participated in the study of measurement properties. The factor analysis revealed a 1-factor solution. Symptomatic participants scored significantly lower than asymptomatic, with a large effect size (P < .001; r = .67). Correlations were of −.60 (P < .05) with the Shoulder and Pain Disability Index questionnaire and −0.66 (P < .05) with the Disabilities of the Arm, Shoulder, and Hand Sports Module questionnaire. Cronbach alpha was .98 (95% confidence interval, .97–.98) and the ICC2,1 was .96 (95% confidence interval .93–.98). No floor or ceiling effects were observed among the symptomatic athletes, while mean time to completion was 121 seconds. Conclusion: The KJOC-Sp is equivalent to the original score, aside from valid and reliable, without floor or ceiling effects in symptomatic athletes and with a low time consumption.
Effects of Collagen and Exercise on Tendon Properties and Pain: A Critically Appraised Topic
Authors: Boldt Kylie S. , Olson Bernadette L. , Thiele Ryan M.
Published: September 2023

Clinical Scenario: Achilles tendon ruptures are prevalent and devastating injuries that require the need for extensive rehabilitation. The methods for preventing these injuries vary between different exercise methods and nutritional supplementation. Although proven effective for decreasing pain and increasing tendon properties, the influence of these 2 methods in combination has not yet been evaluated. Clinical Question: Does exercise combined with collagen supplementation improve Achilles tendon structural and mechanical properties and diminish subsequent patient-reported pain compared with exercise alone in adults? Summary of Key Findings: Exercise training, including eccentric training protocols and concentric resistance training protocols, combined with collagen supplementation influence Achilles tendon properties and subsequent patient-reported pain compared with exercise alone. Clinical Bottom Line: Evidence supports that collagen along with exercise training has a significant influence on pain mitigation, augmented cross-sectional area, and tendon thickness, but may have little to no influence on tendon stiffness and microvascularity compared with exercise alone. Further research is needed to determine the effects of combined methods on various populations. Strength of Recommendation: Collectively, the body of evidence included to answer the clinical question aligns with the strength of recommendation of A.
Lift Me Up: Fostering Belonging Beyond the Classroom
Authors: Carter-Francique Akilah R.
Published: September 2023

The purpose of this article is to encourage administrators, faculty, and staff to foster a sense of belonging for students of color in kinesiology and affiliated academic units at institutions of higher education. Kinesiology is vast and has a range of corresponding workforce careers; however, despite equity, diversity, and inclusion efforts, people of color still lag behind in representation. Acknowledging the current social and legislative climate that seeks to dismantle equity, diversity, and inclusion efforts, the American Kinesiology Association as a leadership-driven membership has the opportunity to further its stance and governance through amplifying the sense of belonging as a social justice practice. Fostering a holistic sense of belonging for students of color beyond the conventional classroom can promote successful student outcomes with increased academic engagement and use of support services, increased personal self-concept and mental health and wellness, and an overall satisfaction with the college experience.
A multifault earthquake threat for the Seattle metropolitan region revealed by mass tree mortality
Authors: Black Bryan A. , Pearl Jessie K. , Pearson Charlotte L. , Pringle Patrick T. , Frank David C. , Page Morgan T. , Buckley Brendan M. , Cook Edward R. , Harley Grant L. , King Karen J. , Hughes Jonathan F. , Reynolds David J. , Sherrod Brian L.
Published: September 2023

Compound earthquakes involving simultaneous ruptures along multiple faults often define a region’s upper threshold of maximum magnitude. Yet, the potential for linked faulting remains poorly understood given the infrequency of these events in the historic era. Geological records provide longer perspectives, although temporal uncertainties are too broad to clearly pinpoint single multifault events. Here, we use dendrochronological dating and a cosmogenic radiation pulse to constrain the death dates of earthquake-killed trees along two adjacent fault zones near Seattle, Washington to within a 6-month period between the 923 and 924 CE growing seasons. Our narrow constraints conclusively show linked rupturing that occurred either as a single composite earthquake of estimated magnitude 7.8 or as a closely spaced double earthquake sequence with estimated magnitudes of 7.5 and 7.3. These scenarios, which are not recognized in current hazard models, increase the maximum earthquake size needed for seismic preparedness and engineering design within the Puget Sound region of >4 million residents.
Polysome propensity and tunable thresholds in coding sequence length enable differential mRNA stability
Authors: Rahaman Sayanur , Faravelli Simone , Voegeli Sylvia , Becskei Attila
Published: September 2023

The half-life of mRNAs, as well as their translation, increases in proportion to the optimal codons, indicating a tight coupling of codon-dependent differential translation and degradation. Little is known about the regulation of this coupling. We found that the mRNA stability gain in yeast depends on the mRNA coding sequence length. Below a critical length, codon optimality fails to affect the stability of mRNAs although they can be efficiently translated into short peptides and proteins. Above this threshold length, codon optimality–dependent differential mRNA stability emerges in a switch-like fashion, which coincides with a similar increase in the polysome propensity of the mRNAs. This threshold length can be tuned by the untranslated regions (UTR). Some of these UTRs can destabilize mRNAs without reducing translation, which plays a role in controlling the amplitude of the oscillatory expression of cell cycle genes. Our findings help understand the translation of short peptides from noncoding RNAs and the translation by localized monosomes in neurons.
Piezo1 activates noncanonical EGFR endocytosis and signaling
Authors: Pardo-Pastor Carlos , Rosenblatt Jody
Published: September 2023

EGFR-ERK signaling controls cell cycle progression during development, homeostasis, and disease. While EGF ligand and mechanical inputs can activate EGFR-ERK signaling, the molecules linking mechanical force to this axis have remained mysterious. We previously found that stretch promotes mitosis via the stretch-activated ion channel Piezo1 and ERK signaling. Here, we show that Piezo1 provides the missing link between mechanical signals and EGFR-ERK activation. While both EGF- and Piezo1-dependent activation trigger clathrin-mediated EGFR endocytosis and ERK activation, EGF relies on canonical tyrosine autophosphorylation, whereas Piezo1 involves Src-p38 kinase-dependent serine phosphorylation. In addition, unlike EGF, ex vivo lung slices treated with Piezo1 agonist promoted cell cycle re-entry via nuclear ERK, AP-1 (FOS and JUN), and YAP accumulation, typical of regenerative and malignant signaling. Our results suggest that mechanical activation via Piezo1, Src, and p38 may be more relevant to controlling repair, regeneration, and cancer growth than tyrosine kinase signaling via canonical EGF signaling, suggesting an alternative therapeutic approach.