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OBJECTIVES: To examine the feasibility of individuals with spinal cord injury or disease (SCI/D) to perform combined oropharyngeal and respiratory muscle training (RMT) and determine its impact on their respiratory function. METHODS: A prospective study at a single Veterans Affairs (VA) Medical Center. Inclusion criteria included: 1) Veterans with chronic SCI/D (>6 months postinjury and American Spinal Injury Association (ASIA) classification A-D) and 2) evidence of OSA by apnea-hypopnea index (AHI ≥5 events/h). Eligible participants were randomly assigned to either an experimental (exercise) group that involved performing daily inspiratory, expiratory (using POWERbreathe and Expiratory Muscle Strength Trainer 150 devices, respectively), and tongue strengthening exercises or a control (sham) group that involved using a sham device, for a 3-month period. Spirometry, maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP), polysomnography, and sleep questionnaires were assessed at baseline and at 3 months. RESULTS: Twenty-four individuals were randomized (12 participants in each arm). A total of eight (67%) participants completed the exercise arm, and ten (83%) participants completed the sham arm. MIP was significantly increased (p

STUDY OBJECTIVES: Sleep-disordered breathing (SDB) is common in the Veteran population. In this retrospective study, we investigated the prevalence of comorbid central and obstructive SDB and the response rate to PAP among Veterans. METHODS: Veterans were screened from a single VA medical center who had polysomnography (PSG) study from 2017 to 2021 to ascertain the presence, severity, and type of SDB by measuring the apnea-hypopnea index (AHI) and central apnea index (CAI). Patients were excluded if they did not have complete studies (diagnostic and PAP titration studies). The inclusion criteria for these analyses were central sleep apnea (CSA) defined as AHI ≥ 10 events/hour and CAI ≥ 5 events/hour. Diagnostic CSA only was defined as AHI ≥ 10 events/hour and CAI ≥ 50% of AHI. OSA only was defined if AHI ≥ 10 events/hour and CAI  5 events/hour but

PURPOSE: Sleep-disordered breathing (SDB) is a common sleep disorder in veterans; however, limited research exists in women veterans. We sought to estimate patterns of care in terms of evaluation, diagnosis, and treatment among women veterans with factors associated with elevated SDB risk. METHODS: Within one VA healthcare system, women identified through electronic health record data as having one or more factors (e.g., age >50 years, hypertension) associated with SDB, completed telephone screening in preparation for an SDB treatment study and answered questions about prior care related to SDB diagnosis and treatment. RESULTS: Of 319 women, 111 (35%) reported having completed a diagnostic sleep study in the past, of whom 48 (43%) were diagnosed with SDB. Women who completed a diagnostic study were more likely to have hypertension or obesity. Those who were diagnosed with SDB based on the sleep study were more likely to have hypertension, diabetes, or be ≥50 years old. Of the 40 women who received treatment, 37 (93%) received positive airway pressure therapy. Only 9 (24%) had used positive airway pressure therapy in the prior week. Few women received other treatments such as oral appliances or surgery. CONCLUSIONS: Findings support the need for increased attention to identification and management of SDB in women veterans, especially those with conditions associated with elevated SDB risk.

While there are some hydrogen refueling stations (HRS) functioning in different parts of the world, their use is not widespread enough, primarily due to their expensive cost. Hydrogen compression is a main contributor to the capital and operation costs of the HRS. By improving H2 compression technology, it is possible to optimize the infrastructure for refueling with hydrogen in terms of cost and performance. The use of metal hydride hydrogen compressors (MHHCs), which have the potential to be inexpensive and have the ability to use waste heat and renewable energy sources for the H2 compression, is a promising solution to overcome this issue. The duration of the H2 compression cycle is nevertheless a serious challenge due to the metal hydride (MH) bed's low heat conductivity. As a heating technique to improve the performance of MHHCs, electromagnetic induction (EMI) is examined numerically for the first time in this work. The dynamic behavior of a two-stage MHHC with each MH reactor having an external heat exchanger and being ringed by a copper coil traversed by an alternating current is described by a two-dimensional mathematical model, which was established and successfully verified by the reference data. Numerical simulations were performed with the help of this model, and the findings showed that the EMI heating method is faster than the heat transfer fluid (HTF) heating technique. For instance, at a delivery temperature of 373 K and a supply pressure of 20 bar, it is possible to produce 106 NL H2 per kilogram of HPMH at a pressure of 97 bar with a 74 % shorter compression time than with the HTF heating technique.

Cooling system design for thermal management of electronic equipment, batteries and photovoltaic (PV) modules is important for increasing the efficiency, safety operation, and long life span the products. In the present study, two different cooling systems are proposed with nano-enhanced multiple impinging jets for a conductive panel. The present cooling systems can be used in electronic cooling and PV modules. Perforated porous object (PPO) and sinusoidal porous object (SPO) are used in the jet cooling system. 2D numerical analysis using finite volume method is conducted considering different values of permeability of the objects (Darcy number (Da) between 10−6 and 10−1). When PPO is used in the cooling system, number of cylinders (between 1 and 6), and size of the cylinders (between 0.015 and 0.075) are considered. In the case of using SPO, amplitude (between 0.1 and 2) and wave number (between 1 and 12) are varied. Alumina-water nanofluid with cylindrical shaped nanoparticles is used as the heat transfer fluid. When permeability is changed for PPO, the average temperature increases by roughly 3.89 °C for a single cylinder and drops by roughly 0.57 °C for a six-cylinder cases. Increasing the size of the cylinder in the PPO case at highest permeability results in temperature drop of 5.3 °C. When changing the number of cylinders, cooling rate varies by about 3.6%. Wave number of SPO is more influential on the cooling performance enhancement as compared to amplitude and permeability of the SPO. The average surface temperature drops by 12.4 °C when the wave number is increased to 12. As compared to reference case of jet impingement cooling without porous object, using PPO and SPO along with the nanofluid result in temperature drop of 12.3 °C and 14.4 °C.

Abstract Recent years have seen an increase in research on biodiesel, an environmentally benign and renewable fuel alternative for traditional fossil fuels. Biodiesel might become more cost-effective and competitive with diesel if a solid heterogeneous catalyst is used in its production. One way to make biodiesel more affordable and competitive with diesel is to employ a solid heterogeneous catalyst in its manufacturing. Based on X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FTIR), the researchers in this study proved their hypothesis that iron oxide core–shell nanoparticles were generated during the green synthesis of iron-based nanoparticles (FeNPs) from Camellia Sinensis leaves. The fabrication of spherical iron nanoparticles was successfully confirmed using scanning electron microscopy (SEM). As a heterogeneous catalyst, the synthesised catalyst has shown potential in facilitating the conversion of algae oil into biodiesel. With the optimal parameters (0.5 weight percent catalytic load, 1:6 oil—methanol ratio, 60 °C reaction temperature, and 1 h and 30 min reaction duration), a 93.33% yield was attained. This may be due to its acid–base property, chemical stability, stronger metal support interaction. Furthermore, the catalyst was employed for transesterification reactions five times after regeneration with n-hexane washing followed by calcination at 650 °C for 3 h.

Due to the outstanding thermal properties of nanoparticles, scientists have introduced a range of multidisciplinary applications in fields such as heat transfer systems, thermal management, solar energy, chemical processes, manufacturing, and cooling technologies. The aim of the current paper is to inspect the heat and mass transfer pattern during Maxwell nanofluid flow considering the diffusion phenomenon. The suspension of microorganisms has been considered for bioconvective flow. The inspection of heat transfer is analyzed by adopting the nonlinear radiated effects. The motivations for considering the Maxwell fluid are associated to novel relaxation time features occurring in polymer industry and manufacturing systems. The endorsed flow is caused by periodically oscillating surface with porous medium. The whole mathematical model is developed in terms of partial differential equations (PDE’s). A successful analytical solution is presented via homotopy analysis method (HAM). It is observed that solutal concentration reduces due to modified Duffer Lewis number and Deborah number. The surface heating parameter and magneto-porosity constant enhances the temperature profile. The predicted results convey significant impact in enhancing the energy reservoirs, diffusion applications, nuclear systems, oil industry, storage energy, space exploration etc.

STUDY OBJECTIVES: To assess the association of insomnia symptoms and psychiatric symptoms in patients with spinal cord injury or disease (SCI/D). METHODS: In this cross-sectional observational study, veterans with SCI/D (n = 72; mean = 59.85 ± 10.4 years; 92% male) completed baseline measures, including the Insomnia Severity Index (ISI) during the baseline phase of a clinical trial on treatment of sleep disorders in veterans with SCI/D. Depression severity was measured by the Patient Health Questionnaire (PHQ-9; sleep items excluded), anxiety severity was measured by the Generalized Anxiety Disorder screener (GAD-7), and probable posttraumatic stress disorder (PTSD) was measured by the Primary Care PTSD screener. Blocked regression was used to evaluate the impact of insomnia symptoms (ISI) on mental health measures after accounting for demographics and level of spinal cord injury/disease. RESULTS: On average, participants scored in the mild range for depression (PHQ-9 = 7.4 ± 5.9) and anxiety severity (GAD-7 = 6.1 ± 6.1). In total, 36.1% (n = 26) screened positive for probable PTSD. ISI explained 19% of the variance in PHQ-9 and 20% of the variance in GAD-7 (P < .001) over and above demographics and SCI/D level of injury/disease. Odds of probable PTSD were increased 1.22-fold for each 1 unit increase in ISI (P = .001) after accounting for demographics and level of injury/disease. CONCLUSIONS: In veterans with SCI/D, insomnia severity was linked to depression and anxiety symptom severity and risk of PTSD. Study results warrant further research to evaluate the impact of insomnia treatment on depression, anxiety, and PTSD in patients with SCI/D. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: Treatment of Sleep-disordered Breathing in Patients With SCI; URL: https://clinicaltrials.gov/ct2/show/NCT02830074; Identifier: NCT02830074. CITATION: Kelly MR, Zeineddine S, Mitchell MN, et al. Insomnia severity predicts depression, anxiety, and posttraumatic stress disorder in veterans with spinal cord injury or disease: a cross-sectional observational study. J Clin Sleep Med. 2023;19(4):695-701.

The present study aims to assess the technical feasibility of a novel Metal Hydride-based Solar Thermal Collector (MH-STC) system. This system includes a flat-plate solar collector integrated with a metal hydride bed, a hydrogen compressor, a photovoltaic panel, a hydrogen tank, and a water storage tank. This system combines the principles of a conventional solar thermal collector with the energy storage capabilities of metal hydrides, enabling the storage of surplus thermal energy. The LaNi5 alloy was used as heat storage material. A 3D-mathematical model is established and a numerical code written in Fortran-90 is developed to simulate the dynamic behavior of the proposed solar thermal collector. It was shown that the developed 3D-model produces computational results that are consistent with experimental data. In addition, to check the accuracy of the mathematical model and numerical approach, the relative errors in the mass balance and energy balance were calculated and values of 0.054 % and 0.18 %, respectively, were obtained.The simulation results offer insights into the system's technical feasibility, revealing an overall efficiency of 90.6 %, the water temperature at the collector outlet can reach 357.3 K, and a water volume heated of 230.4 L under the considered operating conditions. Moreover, the results indicate that the proposed MH-STC system exhibits significant potential as a viable alternative for thermal storage in domestic hot water systems.

_This research delves into the decomposition kinetics of propylene oxide within a novel reactor design characterized by a corrugated inner wall for enhanced cooling. By applying Computational Fluid Dynamics (CFD), this study aims to optimize the reactor's heat transfer capabilities to achieve precise control over the exothermic decomposition process. This approach addresses a previously unexplored area in CFD application, proposing a model that fine-tunes the decomposition efficiency of propylene oxide by considering the interplay of key parameters such as inlet mixture temperature, activation energy, flow rate, and the resulting thermal profile. The primary goal is to advance the development of more efficient and environmentally friendly chemical processing techniques in the propylene oxide industry. The study highlights the critical relationship between activation energy (74–76 kJ/mol), process temperature (29–37 °C), and cooling efficiency in optimizing the decomposition process. Significant findings indicate that higher inlet temperatures (37 °C) and lower activation energies (74 kJ/mol) lead to superior conversion rates. The study presents a clear correlation between temperature elevation, reduced activation energy, and enhanced conversion rates, demonstrating that optimizing these parameters can lead to significantly improved conversion efficiencies, potentially approaching 100 % under ideal conditions.

In this research, a numerical simulation was undertaken to assess the effectiveness of an Evacuated tube solar collector (ETSC). The study explored the efficacy of merging a parabolic trough solar collector (PTSC) and copper fins into the U-tube ETSC design. Two types of fins, namely annular fins and disk-shaped fins, were evaluated. Additionally, the study aimed to analyze the influence of operational and geometric parameters, such as the heat transfer fluid (HTF) mass flow rate and the U-tube bend radius, on the performance of the U-tube ETSC. Furthermore, a comparative examination was carried out to identify the most suitable type of phase change material (PCM) for the U-tube ETSC. Finally, a comparative analysis was conducted to assess the performance of the U-tube ETSC in comparison to that of the coaxial tubes ETSC. The results clearly demonstrated that the integration of an PTSC, PCM, and disk-shaped fins substantially improved the overall performance of the ETSC in comparison to the conventional solar collector. This improvement led to a remarkable increase in energy efficiency, with an impressive gain of 42.94 %. The ETSC displayed remarkable performance, particularly at lower HTF mass flow rates and a reduced U-tube bend radius, achieving an average HTF temperature of 430 K. Additionally, among the tested PCMs, RT 82 emerged as the most suitable choice, providing an energy gain of 9.27 % in comparison with the case without PCM.

_Predicting solar energy is essential for efficient power system planning and the successful integration of renewable energy sources. This study aims to develop a framework for evaluating various machine learning models and feature selection strategies for solar energy prediction. The research applies six machine learning models, i.e., linear regression (LR), random forest (RF), neural networks (NN), K-nearest neighbor (KNN), gradient boosting (GB), and AdaBoost, to datasets from 2019 to 2021 collected at the Abiod Sid Cheikh solar station in southern Algeria. Various statistical indicators, including R2, RMSE, MAE, and Adj-R, were analyzed to assess model performance. The analysis revealed that R2 values ranged from 0.591 to 0.996 kW/m2, RMSE from 0.510 to 1.78 kW/m2, and MAE from 0.357 to 0.856 kW/m2 across different models. KNN and NN models showed significant errors, while GB and RF models demonstrated strong accuracies (RMS = 0.9). AdaBoost and LR excelled in real-time and short-term predictions, exhibiting an RMS of 0.99. This framework offers a comprehensive evaluation method for selecting the most suitable machine learning models and feature selection strategies for solar energy prediction. The findings can assist energy planners and engineers in choosing the appropriate models for accurate solar energy prediction, thereby enhancing the efficiency of power systems. Improved solar energy prediction can contribute to more reliable integration of renewable energy into power grids, supporting the transition to cleaner energy sources and reducing environmental impacts.

Thermal energy storage is necessary for concentrated solar power (CSP) plants; it's a useful technique for reducing fluctuations in the energy supply and aids in peak demand management. Therefore, in the present paper, a novel Hybrid Cascaded Thermal Energy Storage (Hyb-CTES) unit is proposed for use in solar-driven Rankine steam power plant. The concept of the heat storage hybridization examined in this study is to couple metal hydride-based thermochemical heat storage system with cascaded phase change materials-based latent heat storage. To assess the dynamic behavior of the Hyb-CTES unit, a two-dimensional transient model is established, and a computational code is developed. The mathematical model has been validated successfully by comparing it with experimental data and by verifying both the mass and energy balance. To choose the appropriate PCM's melting temperature, four approaches are proposed and tested. Numerical simulations were performed with the help of the developed computer code, and the findings demonstrated that the supplied hydrogen pressure and the temperatures of the metal hydride beds are the crucial parameters for determining the PCM melting temperature. In addition, it is found that the proposed cascaded PCMs configuration enhances the heat storage unit's thermal performance and can reduce the heat charge/discharge cycle duration by 19 %. Also, the results indicate that the new Hyb-CTES unit is a promising alternative for thermal storage for CSP plants.

Efficient cooling system design with impinging jets becomes an important topic due to its higher cooling performance applicable to engineering systems such as in electronic cooling, photovoltaic panels and material processing. In the present study, cooling of an oscillating hot object is considered by using a double slot jet impingement system in the presence of a uniform inclined magnetic field. The oscillation of body and magnetic field can be present in the system or they can be considered as methods for flow and convective heat transfer control for the slot-jet impingement system. Analysis is done for a range of values for the jet Reynolds number (Re ranging from 100 to 500), Hartmann number (Ha, ranging from 0 to 10), inclination of magnetic field (γ, ranging from 0 to 90), and oscillation amplitude (Amp, between −3 and 3) by using finite element method with Arbitrary Lagrangian–Eulerian technique. It is observed that due to the hot object’s oscillating nature, cooling is either increased or worsened for different time steps based. When Re is raised from the lowest to highest value, average Nusselt number (Nu) increases by a factor of 2.4. In the cooling system with impinging jets, strength of magnetic field and its inclination may be employed to regulate the vortex size and distribution. In comparison to the absence of magnetic field, the average Nu falls by around 73% to 75.5% at the greatest magnetic field strength. When oscillation is enabled, cooling performance is increased adopting the time step. By comparing the oscillating object with stationary one, cooling performance improvements of 28% and 8.3% are obtained at (Re, Ha)=(500, 0), and (500, 10) parametric combinations.

Based on enhanced thermal performances of hybrid nanomaterials, various multidisciplinary applications of such hybrid nanofluids are presented in the cooling processes, HVAC systems, energy sectors, boosting the energy sources, automotive thermal systems etc. Owing to such motivated applications in mind, different mathematical models are developed. However, the thermal analysis for hybrid nanofluid with help of fractional models is not focused properly. Therefore, the objective of current research is to develop a mathematical model for enhancement of heat transfer by using the hybrid nanofluid. The decomposition of zinc oxide (ZnO) and ferric oxide (Fe3O4) with kerosene oil base fluid is used for identifying the thermal reflection of hybrid nanofluid. The motivations to improve the thermal prospective of kerosene oil is due to its importance in the energy sources as a fuel and industrial applications like solvent, degreaser and operation of air craft. The vertical moving surface is used to initiates the flow. The natural convective flow is further perturbed with applications of mixed convection effects. The evaluation for heat transfer is inspected by incorporating the external heat source. The mathematical modelling of problem is presented via fractional expressions. The Prabhakar scheme is used to develop the analytical expressions. The accuracy of implemented scheme is inspected by comparing the numerical data computed via Zakian, Stehfest and Tzou's algorithms. The significance of problem is visualized in view of involved parameters like fractional parameters, nanoparticles volume fraction, Grashof number and Prandtl number. The results claim that the enhancement in heat transfer due to decomposition of zinc oxide and ferric oxide nanoparticles is more exclusive as compared to simple nanofluid. The heat transfer enhanced due to nanoparticles volume fraction.

One of the most effective techniques for electronic-cooling devices involves the use of nanofluid, a substance known for its superior heat transfer capabilities. The main challenge in modern production engineering lies in the efficient cooling of electronic devices. Nanofluids have attracted widespread interest in various technical fields due to their exceptional characteristics, which enable effective cooling of electronic devices while improving energy efficiency. In the field of electronic systems, engineers are exploring the potential of nanofluids in a range of applications and phenomena. Choosing the right heat transfer fluid to dissipate heat is crucial in managing electronic component temperatures. This study examines the effects of heat sinks and thermal radiation on the flow of Darcy-Forchheimer nanofluid over a vertical plate, with the aim of enhancing the thermal durability of electronic components. The governing mathematical model has been refined to accurately represent the physical coefficients. To develop a relevant algorithm in the FORTRAN environment, primitive variables are employed in steady-state and oscillatory models, nanomaterial and heat sink. Outputs are presented numerically and graphically using Tecplot 360, revealing that an increase in heat sink capacity leads to a reduction in surface temperature due to the heat sink's ability to absorb excess thermal energy. The use of porous Darcy-Forchheimer material is shown to lower the fluid temperature. The study also shows that the heat transfer rate decreases with an increase in the heat sink coefficient, and the oscillatory frequency of heat transfer reduces with a decrease in the Prandtl number. Decreasing behavior of heat transfer is depicted for maximum thermophoretic factor due to heat sink impact.

This study undertook the experimental enhancement of dispersion stability in graphene-based nanofluids to boost the performance of concentric counterflow heat exchangers. Emphasis was placed on the characterization and preparation of graphene suspensions by evaluating their dispersion properties in various solvents: water, ethanol, acetone, and dimethylformamide (DMF). The graphene powder underwent comprehensive analysis using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR). Subsequently, graphene suspensions were prepared and uniformly mixed using both a magnetic stirrer and an ultrasonic vibrator. The investigation confirmed that solvent type significantly influences the stability and solubility of the suspensions. Solutions of reduced graphene oxide (rGO) in water, ethanol, and DMF exhibited remarkable long-term stability, contrasting with those in acetone. Water emerged as the superior solvent for developing the thermal transport fluid. The addition of graphene resulted in a conductivity increase of approximately 48.15% at φ = 0.5% concentration, while the best thermal efficiency was attained at φ = 0.35% and a flow rate of 3 L/min. Furthermore, at lower flow rates, it is advisable to avoid higher concentrations to maintain optimal thermal efficiency.

In today’s interconnected world, with the changes caused by the technological revolution conflicts, politics, diseases and climate changes, along with the growing influence of artificial intelligence (AI), the threat of manipulating data is on the rise. In the field of satellite imagery, data transfer security is especially crucial. One of the most important tools for safeguarding satellite images during storage and transmission is cryptography. It offers an imperceptible substitute to quick response codes. The literature focuses predominantly on software implementations of encryption techniques, despite scenarios where hardware cryptographic solutions are preferable or necessary due to increased requirements for speed, power, or data security. IP cores offer a versatile and widely applicable solution for hardware development, serving as the basic building blocks for constructing processors on field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs). This paper presents an innovative embedded chaotic algorithm designed to enhance the security of satellite images by integrating Ribonucleic Acid (RNA)-encoded encryption, Fisher-Yates shuffling and the Fractional order 4D Chen system. To achieve an optimal balance between encryption time and security, the original image undergoes strategic block division, with each block undergoing encryption via a series of steps including XOR operations, RNA dynamic encoding and decoding, RNA dynamic operation rules, and Fisher-Yates shuffle. The primary objective of this study is to enhance the efficiency and speed of the encryption process by presenting the realisation of a robust cryptographic scheme in the form of an IP core tailored which has been implemented on ZedBoard FPGA using the Vivado High-Level Synthesis (HLS) design suite. By utilising the hardware parallelism intrinsic to FPGA architectures, we attain significant enhancements in execution time compared to the software-based implementation (frequency of 160.01 MHz). Experimental and analytical results demonstrate the algorithm’s robust security, resilience to single-event upsets, large key space, and low time complexity.

This paper presents a comprehensive model of hemodynamic pulsatile flow within the carotid artery, examining both normal conditions and those affected by stenosis. The primary focus lies in visualizing shear stress along the inner walls, aiming to elucidate how stenosis alters blood flow characteristics and subsequently impacts plaque deposition. Utilizing advanced computational fluid dynamics simulations, temporal variations in flow patterns, velocity profiles, and pressure gradients resulting from stenosis are captured, thereby elucidating the mechanical forces exerted on arterial walls. Moreover, this study analyzes the influence of hemodynamic parameters, such as Reynolds number, Womersley number, and arterial geometry, on flow disruption and stagnation points. Such insights are critical in understanding the mechanisms underlying plaque formation and progression. Critical thresholds of shear stress and flow patterns contributing to endothelial dysfunction and atherosclerotic lesion initiation are identified by comparing hemodynamic environments in healthy vs stenotic arteries. The results demonstrate significant differences in hemodynamic characteristics between stenosed and normal arteries, particularly near systolic peaks. Stenosed arteries exhibit notably higher velocities at arterial bifurcations during systole than normal arteries, indicative of altered flow dynamics. In addition, stenosis disrupts flow patterns, leading to vortex formation at locations beyond systolic peaks. Overall, findings from this research advance our understanding of cardiovascular disease pathogenesis and provide valuable insights into the hemodynamic effects of arterial stenosis.

This study aims to determine which thermal energy storage (TES) system is most suited for a concentrated solar power (CSP) plant. The question is which the best TES system, whether utilizing a single metal hydride or employing dual metal hydrides with or without reaction heat recovery via phase change material (PCM). The authors noted that no studies have been conducted to address this question thus far. Consequently, the primary aim of this paper is to compare three different TES systems in order to ascertain the viability, efficacy, and performance of the appropriate TES system. The examined TES systems included: (i) TES system 1, based on a single metal hydride tank coupled to a hydrogen tank through an H2 compressor; (ii) TES system 2, based on paired metal hydride tanks without recovering reaction heat; and (iii) TES system 3, based on paired metal hydride tanks incorporating a PCM for reaction heat recovery. To simulate and evaluate the performance of the three TES systems under various operating conditions, a mathematical model and computer program were created and successfully verified. By examining into their thermodynamic performance and practical viability, this study attempts to provide the strengths and limitations of each system. A comparison of the three TES systems' performance indicators indicates that the TES system 1 has the potential to provide a specific power output of 500.8 W/kg of alloy, which is 50.1 % and 76.4 % greater than the TES systems 2 and 3, respectively. With a volumetric storage capacity of 755 MJ/m3, the TES system 2 outperforms the other two TES systems by around 40 %. The TES system 3 can operate with 85.9 % energy storage efficiency. This efficiency is 30.3 % higher than that of the TES system 1 and 10.2 % higher than that of the system 2. Ultimately, the decision to choose either a TES system based on a single metal hydride or one involving paired metal hydrides is hinges on the specific requirements, limitations, and priorities of the TES system under consideration.

This study explores the convective cooling features of a hot rotating cylinder by using the combined utilization of cross-flow on the upper part and multi-jet impingement on the bottom part. The analysis is performed for a range of jet Reynolds number (Re) values (between 100 and 500), cross-flow Re values (between 100 and 1000), rotational Re values (between −1000 and 1000), cylinder size (between 0.25wj and 3wj in radius), and center placement in the y direction (between −1.5wj and 1.5wj). When the cylinder is not rotating, the average Nu increment becomes 102% at the highest jet Re, while it becomes 140.82% at the highest cross-flow Re. When rations become active, the impacts of cross-flow and jet impingement cooling become slight. As compared to a motionless cylinder, at the highest speed of the rotating cylinder, the average Nu rises by about 357% to 391%. For clockwise rotation of the cylinder, a lager cylinder results an increase in the average Nu by about 86.3%. At the lowest and highest cross-flow impinging jet Re value combinations, cooling performance improvement becomes a factor of 8.1 and 2, respectively. When the size of the cylinder changes, entropy generation becomes significant, while the vertical location of the cylinder has a slight impact on entropy generation.

In this study, the incorporation of a flexible baffle structure at the base of a microelectronic channel is examined to determine its impact on thermal and fluid dynamics. The investigation covers two configurations: case 1, where the heat source is situated at the top section of the microchannel, and case 2, with the heat source placed at the bottom. To cool the electronic component, a nanofluid consisting of water with aluminum oxide (Al2O3) nanoparticles, in concentrations varying from 0% to 6%, is injected into the microchannel, exhibiting a periodic velocity profile at the inlet. The governing equations for the system are resolved using the finite element method for numerical simulation. The results show that the shape and curvature of the baffle significantly affect the heat dissipation efficacy. In particular, the setup with the heat source located at the bottom, adjacent to the flexible baffle, demonstrates the most advantageous cooling performance. The data also show a positive relationship between the nanoparticle volume fraction and enhanced heat transfer, particularly when the heat source is near the bottom baffle for shapes with S = −20 and −10, implying superior convective heat transfer. The findings indicate optimal outcomes are achieved when there is a reduction in pressure drop and fluid resistance.