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The traditional 70 MPa liquid hydrogen (LH 2) refueling stations (HRSs) require LH 2 pumps with high outlet pressures, leading to high initial investment, energy consumption, and difficulty in developing an LH 2 pump meeting requirements. Existing LH 2 HRSs using thermal compression eliminate the need for pressurization equipment but result in significant waste due to low-pressure hydrogen venting. Therefore, we have pioneered a novel pump-thermal synergistic pressurization process for an efficient LH 2 HRS system. The process utilizes a 45 MPa LH 2 pump and an electric heating method, allowing easily controllable heat input. This study constructs a thermodynamic model for this system that includes the dynamic operational processes of all core components. Based on the established model, the outlet parameters of the LH 2 pump, characteristic parameters of the pressure vessel, the refueling process, and the operation of the entire system are investigated. By dynamic simulation of the whole HRS system with pump and thermal compression, it is found that the specific energy consumption for hydrogen refueling is reduced to 0.55 kWh/kg, with the pump consuming 0.2 kWh/kg while thermal compression consuming 0.35 kWh/kg. After optimizing control strategies, the cycle venting of the pressure vessel and the residual hydrogen gas after re-heating and pressurization account for only 11.6%, and further utilization through the pump pressurization cycle can achieve high utilization with no residuals. This system effectively reduces the initial investment and energy consumption for LH 2 HRSs. It simplifies the structure, facilitating the retrofit of existing stations and promoting the construction and application of HRSs. [Display omitted] • An advanced hydrogen refueling station with pump and thermal compression is proposed. • A simulation model is developed for HRS with pump and thermal compression. • Thermodynamic analysis of HRS with pump and thermal compression is conducted. [ABSTRACT FROM AUTHOR]

This article thoroughly assesses the Chemical Looping Hydrogen Production (CLHP) process, aiming to enhance understanding of detailed dynamic simulations. It includes a concise historical overview of chemical looping technology, emphasizing recent commercial applications like combustion engines. The article discusses several cases of pilot and sub-pilot scale investigations, along with critical insights to identify the issues surrounding the commercialization of this technology. Furthermore, the review is extended to analyze several aspects of the process to develop a dynamic simulation model, including reactants, operating modes, kinetic parameters, and the process models. Key process materials such as reduction fuel, oxygen carriers and solid supports are carefully chosen to achieve target conversions and net-zero carbon emissions. The three-reactor system is meticulously defined, focusing on closed-loop production's thermodynamic and economic benefits. Detailed information is provided on reactions within each unit and the required operating regimes for continuous solid circulation. The review also examines mathematical modeling methods for dynamic simulation implementation to determine gas-solid profiles at pellet and reactor scales. Simulations derived from this study's concepts can be refined through parameter modification for optimal process operation and control system analysis for real-world industrial applications. Ultimately, this review contributes significantly to the commercialization of CLHP, offering an economically viable solution for sustainable hydrogen production. [Display omitted] • Chemical looping is an economically viable solution for producing hydrogen fuel. • Dynamic models can further the knowledge of chemical looping hydrogen production. • Mathematical simulations can quantify the acclaimed advantages of the process. • Quantified results can drive further investment towards process industrialization. [ABSTRACT FROM AUTHOR]

Unveiling the dynamic active site of defective carbon-based electrocatalysts for hydrogen peroxide production. [Display omitted] Defective carbon materials have emerged as promising candidates for the electrocatalysis of oxygen reduction reaction (ORR) to selectively produce H 2 O 2. However, distinguishing the roles of oxygenates and carbon defects in carbon for 2e- ORR remains to be challenging. In a recent issue of Nature Communications, Yao and coworkers pinpointed the major active sites in oxygenated carbon materials and identified the key intermediate employing a series of dynamic and simulation techniques. In addition to highlight the proposed work, this comment article also discussed pioneering methodologies to characterize structure dynamics and probe the integral active center for rational design of carbon based catalysts with atomic precision. [ABSTRACT FROM AUTHOR]

The efficient production and sustainable operation of water electrolysis hydrogen production equipment within renewable energy systems, characterized by intermittency and volatility, necessitates dynamic simulation for the development of optimized control systems. This paper proposes the application and modification of a data-driven deep-learning model to simultaneously simulate the thermal and electrochemical responses of an alkaline water electrolyzer (AWE), yielding exceptional performance and versatility. By utilizing 4840 h of comprehensive experimental data, the causal relationships among electrolyzer operating parameters are resolved, classifying them into set values and response values for the proposed dynamic model. The model architecture is based on an attention mechanism and designed with hybrid input. Notable enhancements include embedding flow-leveraged polarization function, creating set-value cross-attention, and adopting probability-sparse attention, all of which are validated through both the validation and simulation results. Extensive exploration of various structural and training parameters leads to the selection of the best-performing model. When applied to simulation across all experimental data, the median mean percentage absolute error of the optimal model in cell voltage is a mere 1.3%, while the error in temperature is only 3.5%. Moreover, under typical operating conditions, the simulation error for both voltage and temperature remain below 2%, highlighting the outstanding dynamic modeling and simulation capabilities. These results demonstrate the potential of the proposed model for future hydrogen energy applications in dynamic control and operational optimization within renewable energy system for higher performance and better conversion efficiency. • Deep-learning model for dynamic thermoelectric simulation of water electrolyzers. • Flow-leveraged polarization function and set-value cross-attention mechanism. • Excellent accuracy, thermoelectric error of 3.5% and 1.3%, respectively. • Insights for optimizing control strategies of electrolyzer for higher efficiency. [ABSTRACT FROM AUTHOR]

Iatrogenic aortic dissection is a rare but life-threatening complication of coronary artery bypass surgery. We report a case with incidentally detected iatrogenic aortic dissection related to aorta cross-clamping that was successfully managed with watchful follow-up. The decision making was based on 3-dimensional holographic and fluid dynamic analysis guidance. [ABSTRACT FROM AUTHOR]

In order to prevent damage to the support equipment caused by rock burst, a torsion plate energy absorption member is designed to be used with hydraulic columns. Explicit dynamic simulation is used and compared with the tests. The equations of structural parameters to the mean value of the reaction force (F mean), specific energy absorption (SEA), and mean squared deviation (σ) are constructed based on the response surface method. The structural parameters are optimized using MOPSO. The results indicate that the torsion plate exhibits excellent energy absorption characteristics. The error rate of the simulation compared to the test is less than 5%, indicating a high level of simulation accuracy. All three sets of response fitted equations have R 2 above 0.97, indicating a good fit. The three evaluation indexes demonstrate a trend of increasing then decreasing as the torsion angle increases. The wall thickness is positively correlated with the influence of each parameter index, while the effect of fillet radius is reversed. The maximum relative error of the predicted value is 9.50%. After optimization, the F mean is effectively increased by more than 78%, the SEA is increased by more than 24.72%. The σ is increased by 8.31%, the optimization effect is remarkable. [Display omitted] [ABSTRACT FROM AUTHOR]

This study developed a finite element method (FEM) dynamic simulation to visualize the deployment behavior of thin membrane structures in the space environment. The proliferation of space debris resulting from accelerated space development threatens the future of space. Numerous researchers have explored strategies to prevent artificial structures from remaining in space and becoming space debris. One such method involves utilizing a drag sail device to de-orbit artificial structures, which reduces their kinetic energy by inducing additional atmospheric drag, allowing them to re-enter the Earth's atmosphere. Tohoku University and Nakashimada Engineering Works, Ltd. have successfully developed a deployable membrane structure for de-orbit purposes and demonstrated its effectiveness in space. Space structures, such as membranes, exhibit highly nonlinear behavior due to their flexible properties, and ground tests by actual devices cannot fully demonstrate their deployment stability in a microgravity environment. Therefore, evaluating the deployment behavior using simulation methods instead of relying solely on hardware development is crucial. In this study, we employed FEM to establish a simulation environment, which enables us to consider nonlinear oscillations of flexible structures, such as the membrane. The simulation results closely reproduce the deployment motion observed in ground tests by appropriately incorporating constraint conditions related to deployment forces and hardware interactions, such as a hub component initially wrapped by the membrane. The simulation facilitated an assessment of the impact of membrane properties on deployment without the need for physically developing an actual hardware device. We proposed evaluation methods for determining membrane properties in terms of the trend of propagation of deployed surface area and the tendency of deployment motion. This established simulation technique can be utilized to develop future flexible space structures. • De-orbit Membrane Mechanism (DOM) was developed as a satellite de-orbit application. • Formulate nonlinear FEM analysis of non-spin type deployable structures. • Modeling techniques of the membrane in simulation. • Evaluation of the membrane deployment between simulation and ground experiments. • Proposed methods can be used to predict the deployment behavior of the actual membrane. [ABSTRACT FROM AUTHOR]

The launcher recovery method known as 'In-Air Capturing' is an innovative approach where a winged rocket stage is captured mid-air by an aircraft and subsequently towed back to the launch site. To achieve this, a capturing device attached to a tether is released from the towing aircraft. This device autonomously connects the reusable launch vehicle to the aircraft, while the two vehicles are in proximity. The tether's flexible dynamics have a strong influence on the maneuverability of the capturing device. Thus, it is critical to model the dynamics of the tether to get a realistic understanding and to evaluate feasibility of the concept. However, precise modelling and control of highly flexible systems with large deformations is both challenging and computationally intensive. For engineering applications which involve closed-loop simulations, finding a trade-off between accuracy and computational effort is crucial. In this paper, the tether is modelled as a discretized chain of rigid bodies connected by rotational springs at the joints. The tether along with the capture system is integrated in a simulation model and open loop tests are performed to analyse the system characteristics. The tether properties are studied to find a suited configuration for 'In-Air Capturing'. • Multibody modelling approach for long cable like bodies with large deformation. • Capture system dynamics for the unique 'In-Air Capturing' launcher recovery concept. • Dynamic modelling for the complete capturing system including towing aircraft, capturing device and tether. • Assessment of tether properties suited for 'In-Air Capturing' with sensitivity studies. [ABSTRACT FROM AUTHOR]

Heterotrimeric GTP-binding protein alpha subunit (Gα) and its cognate regulator of G-protein signaling (RGS) protein transduce signals in eukaryotes spanning protists, amoeba, animals, fungi, and plants. The core catalytic mechanisms of the GTPase activity of Gα and the interaction interface with RGS for the acceleration of GTP hydrolysis seem to be conserved across these groups; however, the RGS gene is under low selective pressure in plants, resulting in its frequent loss. Our current understanding of the structural basis of Gα:RGS regulation in plants has been shaped by Arabidopsis Gα, (AtGPA1), which has a cognate RGS protein. To gain a comprehensive understanding of this regulation beyond Arabidopsis, we obtained the x-ray crystal structures of Oryza sativa Gα, which has no RGS, and Selaginella moellendorffi (a lycophyte) Gα that has low sequence similarity with AtGPA1 but has an RGS. We show that the three-dimensional structure, protein-protein interaction with RGS, and the dynamic features of these Gα are similar to AtGPA1 and metazoan Gα. Molecular dynamic simulation of the Gα-RGS interaction identifies the contacts established by specific residues of the switch regions of GTP-bound Gα, crucial for this interaction, but finds no significant difference due to specific amino acid substitutions. Together, our data provide valuable insights into the regulatory mechanisms of plant G-proteins but do not support the hypothesis of adaptive co-evolution of Gα:RGS proteins in plants. [ABSTRACT FROM AUTHOR]

Unveiling the mechanisms and process of the interfacial reaction between transition metal oxides and metals have far-reaching implications for their superior application. Herein, the interfacial reaction between ZrO 2 and metals was comparatively studied, and the interfacial reactions between three types of ZrO 2 and Zr were systematically investigated by MD simulations. Comparative experiments show that the c -ZrO 2 reacts more vigorously with the active metal than the m -ZrO 2 under the same conditions, and modified c -ZrO 2 nanoparticles have core-shell structures due to the resulting oxygen concentration gradient. The MD simulations reveal that the crystal structure of ZrO 2 has a great influence on its oxygen loss rate (5.14 %–6.46 %) and oxygen distribution induced by the ZrO 2 /metal interface reaction. Meanwhile, the differences in ZrO 2 properties lead to two modes of ZrO 2 /metal interfacial reactions, which are distinguished by the characteristics of the oxygen distribution in the modified ZrO 2. One is that there is no obvious oxygen concentration gradient inside the ZrO 2 during the interfacial reaction, and the crystal defects in the modified ZrO 2 are uniformly distributed, such as c -ZrO 2 and t-ZrO 2. Another reaction mode is that only the region immediately adjacent to the interface in ZrO 2 undergoes diffusion of oxygen ions to the metal, and the interfacial reaction process proceeds layer by layer, such as m -ZrO 2. In addition, when the oxygen density and V O density of ZrO 2 are both low while the oxygen conductivity is high, the ZrO 2 /metal interfacial reaction tends to proceed according to mode A, resulting in modified ZrO 2 with uniformly distributed defects. [ABSTRACT FROM AUTHOR]

The catalyst is crucial in enhancing productivity within the Fischer-Tropsch synthesis (FTS). The metal support interaction (MSI) plays a pivotal role in the FTS catalyst performance, impacting activity, stability, and selectivity. he configuration and composition of the catalyst dramatically impact MSI, with a strong MSI (SMSI) specified for the core-shell structure. In this study, two methods consisting of chemical treatment of etching and adding a promoter (Ru) for tuning the SMSI of the FTS catalyst are presented, and their footprints on the catalysts' performance are screened by utilizing various characterization tests, molecular dynamic simulation, and catalytic tests. It is recognized that the silica interfacial perimeter acts as a barrier that restricts the charge transfer and boosts the SMSI in the silica-coated catalyst. Conversely, the etched catalyst exhibits a moderate MSI, contributing to increased reducibility, stability, and activity. Furthermore, the Ru-doped etched catalyst represents the optimum MSI, resulting in the highest overall performance. [Display omitted] • The catalyst's structure, configuration, and composition significantly affect the metal support interaction (MSI). • Chemical etching and a promoter (Ru) are used to tune the SMSI of the FTS catalyst and intensify its performance. • The etched catalyst exhibits a moderate MSI, increasing ease of reduction, stability, and activity. • The etched catalyst undergoing doping with Ru with the outer shell of ceria promotes the formation of oxygen vacancies. • Ru NPs have a significant effect on the electron charge surface density of the catalyst. [ABSTRACT FROM AUTHOR]

• A traditional R134a and a novel R744 cooling units are compared over their lifetime. • Dynamic numerical simulations are used to assess the performance during operation. • The total carbon footprint of the units is evaluated from a life cycle perspective. • On annual basis, the R744 unit COP is 27.5 % higher than the R134a unit. • The lifetime carbon footprint of the R744 unit is 34.8 % lower than the R134a unit. In recent years, the temperature-controlled transport sector has experienced a substantial growth, and this trend is expected to accelerate in the coming years. However, as the sector expands, it becomes imperative to address and mitigate the carbon footprint of transport refrigeration systems. The carbon footprint of a refrigeration system comprises both direct emissions from refrigerant leakage and indirect emissions derived from energy consumption. In this study, dynamic numerical simulations are used to evaluate the annual performance of a conventional HFC (R134a) transport refrigeration unit and of a newly developed natural refrigerant (R744) one employed in a multi-drop delivery mission in urban environment. Additionally, a simplified life cycle approach is used to compare the carbon footprint of these cooling units across various stages of the system supply chain, including refrigerant production and recycling, unit manufacturing, operation and disposal. Results show that the R744 unit presents significantly higher COP for high ambient temperatures, while its performance is degraded for low ambient temperatures due to low duty cycle. On annual basis, the R744 unit COP is 27.5 % higher than the R134a one. However, the increased weight of the R744 unit results in significantly higher emissions associated with fuel consumption required to transport the unit weight, leading to slightly higher fuel related emissions (+9.3 %) for the R744 unit. Nevertheless, the high GWP of R134a contributes to substantial direct emissions due to refrigerant leakages, resulting in an overall 31.9 % reduction in the lifetime CO 2 equivalent emissions for the R744 unit when considering the total emissions. [ABSTRACT FROM AUTHOR]

Numerical simulation based on the discrete phase model and dynamic mesh model can more accurately simulate the working process for hybrid rockets, including the motion and evaporation process of particles and regression process of the fuel grain. The dynamic numerical simulation of combustion and flow in hybrid rocket motors based on a discrete phase model is carried out. Aluminum and aluminum hydride are added to the internal flow field as discrete droplets. Then, a hybrid rocket is designed with 95 % hydrogen peroxide as oxidizer and 38 % aluminum hydride+20 % aluminum+42 % hydroxyl-terminated polybutadiene as the fuel and used to verify the model by firing test. A high degree of agreement between experiment and simulation findings is found. The average deviations for thrust and pressure are 3.6 % and 5.9 %, respectively. It offers the required backing for using the simulation method to investigate the flow and combustion process for the hybrid rockets. The results also demonstrate the transient characteristics of the inner flow field, including the separation and merging of vortexes in the pre-chamber. It is found that a peak of the regression rate appears at the front of the grain and moves backward. This is mainly because the vortex appears here and enhances its heat transfer. Through the discrete phase model, it is worth noting that the aluminum droplet content gradually decreases at the nozzle over time, which is consistent with the firing test. Further research on the impact of aluminum hydride content on the performance of the hybrid rockets has been carried out. The results show that the higher aluminum hydride content can lead to better performance for the hybrid rockets. The thrust, pressure, specific impulse, and characteristic velocity enhance with the increase of aluminum hydride content. An interesting discovery is that the average regression rate is maximum at 48 % aluminum hydride content. This research innovatively couples dynamic mesh and discrete phase models, which can help better understand the working process for hybrid rockets and provide important guidance for the selection of fuel formula. • A simulation model of hybrid rocket motors based on a discrete phase model is established. • The motion and evaporation of particles and regression of the fuel grain are simulated. • A test of hybrid rockets with fuel containing aluminum and aluminum hydride is carried out. • A high degree of agreement between experiment and simulation findings is found. • The impact of aluminum hydride content on the performance of the hybrid rockets is conducted. [ABSTRACT FROM AUTHOR]

• Supercritical water gasification mechanism of R410A is studied. • Gasification process of R410A in supercritical water is described. • Hydrogen bonds are formed between R125 and H 2 O, and between R125 and R32 molecules. • Hydrogen bonds promote the decomposition of R32 and inhibit the decomposition of R125. • HF, H 2 and CO rich products could be selectively obtained. Harmless treatment and resource utilization of the waste HFC refrigerants have gradually become the focus of attention. As a clean waste resource utilization technology, supercritical water gasification has good potential in converting waste refrigerant into high value-added chemicals and fuels. In this study, the supercritical water gasification mechanism of R410A, and the interaction mechanism between R125 and R32, and between H 2 O and R410A during the gasification process are investigated by using ReaxFF reactive molecular dynamic simulation and density functional theory calculation study. The results show that the main products obtained from the supercritical water gasification of R410A are HF, H 2 , CO and CO 2. More than 90 % of F atoms in R410A can be mineralized to form HF molecules. H 2 and CO are two important syngas products during the supercritical water gasification process. Hydrogen bonds are generated between R125 and H 2 O molecules and between R125 and R32 molecules, which leads to the decomposition of R125 molecules more easily, and the decomposition of R32 molecules more difficult. This work provides a possible way to convert waste HFC refrigerant mixture into high value-added chemicals and syngas. [ABSTRACT FROM AUTHOR]

Therapeutic targeting of Sp1 transcription factor and survivin, are studied in various cancers due to their consistent overexpression. These markers result in poorer cancer prognoses and their downregulation has been investigated as an effective treatment approach. Mithramycin-A and Tolfenamic acid are two drugs with innate anti-cancer properties and are suggested to be able to target Sp1 through GC/GT DNA binding interference, however in-depth binding and mechanistic studies are lacking. Through docking analysis, we investigated Mithramycin-A and Tolfenamic acid in terms of their specific binding interactions with Sp1 and survivin. Through further molecular dynamics simulations including Root Mean Square (RMS) Fluctuation and RMS Deviation, rGYr, and H-bond analysis, we identified critical residues involved in drug interactions with each protein in question. We show Mithramycin-A as the superior binding candidate to each protein and found that it exhibited stronger binding with Sp1, and then survivin. Subsequent molecular dynamics simulations followed the same trend as initial binding energy calculations and showed crucial amino acids involved in each Mithramycin-A-protein complex. Our findings warrant further investigation into Mithramycin-A and its specific interaction with Sp1 and their downstream targets giving a better understanding of Mithramycin-A and its potential as an effective cancer treatment. [Display omitted] • Docking studies showed binding affinity for both Mithramycin and tolfenamic acid with Sp1 and BIRC5. • Docking analysis confirmed that Mithramycin exhibits higher binding affinity in compared to Tolfenamic acid. • Molecular Docking/Dynamic Simulation studies are consistent with in vitro results using Ewing sarcoma cells. • Intermolecular H-bonds revealed novel bonds and interactions forming post Molecular Dynamic simulations. [ABSTRACT FROM AUTHOR]

Polymer electrolyte membrane fuel cells (PEMFCs) offer a clean and efficient energy generation technology. However, optimizing their performance in terms of water transport through the electrolyte membrane remains a challenge. In this study, we employ molecular dynamics simulation and nuclear magnetic resonance (NMR) experiments to investigate the influence of carbon materials and membrane thickness on water diffusion within the triple phase boundary of a PEMFC. Our theoretical investigation highlights the significant impact of Nafion content on water morphology within the system. The structural analysis reveals the intricate interplay between material properties and water behavior in confined environments. The formation of water channels facilitated by the ionomer enhances water mobility, while excessive ionomer content leads to reduced diffusion coefficients. Experimental measurements using NMR diffusion validate the correlation between our simulation results and real-world observations. Furthermore, our Molecular Dynamic (MD) and NMR studies identify the optimal performance range for ionomer content, with systems containing 12 to 24 oligomers (20–30 % w/w) exhibiting superior water diffusion within Vulcan Carbon (VC) structures. By shedding light on water transport phenomena in PEMFCs, our findings contribute to a better understanding of fuel cell performance and provide valuable insights for the design and optimization of fuel cell systems. [Display omitted] • The formation of water channels facilitated by the ionomer greatly enhances water mobility in fuel cell membranes. • 20-30% ionomer content exhibit the best performance in terms of water diffusion. • This work provide insights into water behavior in PEMFC triple phase boundary. [ABSTRACT FROM AUTHOR]

It is great significant to explore the changes of compressor performance for hydrogen transportation. We found that a Gray-RBF neural network prediction model improved prediction accuracy. The prediction error of the model is 2.34 % by data verification. It was found that the hydrogen blending ratio was increased from 0 % to 30 %, the pipeline transmission power was reduced by 9.3 %. Simultaneously injecting hydrogen to natural gas causes the performance curve of the compressor to shift downwards. The pressure ratio decreases by 18.9 % and shaft power decreases by 28.6 % when the hydrogen blending ratio increases from 0 % to 30 %. The injection of hydrogen to natural gas causes the surge range of the compressor to increase, so the stable range to narrow. In general, this research may provide reference and guidance for the transportation research of hydrogen blended natural gas and compressor operation about gas industry. [Display omitted] • Creating a combination model improved the accuracy of performance prediction. • Injecting hydrogen into natural gas reduced the power of pipeline gas transmission. • Enlarging initial pressure caused the gas transmission power increase. • Injecting hydrogen into natural gas caused decreases of compressor performance curves. • Injecting hydrogen into natural gas increased the surge range of the compressor. [ABSTRACT FROM AUTHOR]

Catalysts with dual functions in hydrogen production and storage are desired for the low-cost technology. In the preceding view, we used reactive force molecular dynamics to demonstrate how effective the Fe–Al core-shell structure is at breaking up water molecules and storing hydrogen free radicals via thermochemical water splitting. The results show that at T ∼600 K, water molecules begin to dissociate in the presence of a Fe–Al catalyst, releasing OH and H free radicals. It is worth noting that the produced OH free radicals are bonded to the Al-shell, whereas the H free radicals move to the Fe-core and stores via chemical bond. Interestingly, at T < 1200 K, there is no Fe–O bond. This could be due to Al having a higher oxidation potential than Fe, causing OH free radicals to preferentially associate with the Al-shell. Furthermore, at 2000K < T > 3000 K, the number of Fe–H bonds decreases while the number of H–H bonds increases, indicating that the stored H atom desorbs and forms an H 2 molecule. Temperature can thus be used to monitor the ability of Fe–Al catalysts to dissociate water, store hydrogen, and produce hydrogen. This research shows that developing core-shell type catalysts can provide an effective solution for hydrogen generation, storage, and transportation. • Fe–Al core-shell catalysts are efficient for dissociation of water molecules at T∼600 K. • Water dissociates into OH and H free radicals. • OH radical bonded to the Al-shell (Al–OH), whereas H radical bonded to Fe-core (Fe–H). • At temperature 2000K < T > 3000 K, Fe–H bonds dissociate and H 2 molecule generates. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cells have become one of the most viable power sources for electric aircraft. Models representing the electrical behavior of the fuel cell stack over the full dynamic operation region are essential for the development of power electronic energy systems powered by fuel cell stacks. This work presents an electrical equivalent circuit model for PEM fuel cell stacks representing the static and dynamic electrical behavior of the fuel cell stack under pulsed loads up to frequencies of 10 kHz. Dynamic phenomena on time scales slower than the considered timescale of power-electronic switching, such as reactant flow, membrane hydration, and temperature effects, are considered stationary. The parameterization method proposed is developed on measured data from a 110 W PEM fuel cell stack and validated with a set of measured data from a 2 kW stack. The time-domain simulated behavior of the parameterized model shows an accurate representation of the measured behavior: the parameterized model reproduces both the static polarization behavior and the behavior under high-frequency pulsed loading with errors of less than 1% with respect to the nominal stack voltage. The model is suitable for dynamic simulation of power electronic systems directly connected to fuel cell stacks and can be parameterized without special electrochemical impedance spectroscopy measurements. • A novel equivalent circuit model for PEM fuel cells is proposed. • The equivalent circuit model is valid in time domain for large-signal perturbations. • The model represents the dynamic electrical behavior under pulsed loads up to 10 kHz. • The proposed model is parameterized using a novel pulsed load measurement method. • The model is aimed for highly dynamic simulations of fuel cells in pHiL environments. [ABSTRACT FROM AUTHOR]

Green hydrogen is currently eye-catching in terms of its production, storage and delivery to facilitate energy transition. In the present research, it is tried to demonstrate the capability of green hydrogen in blending with syngas (produced by biomass gasification) to feed an SOFC system in order to supply electrical power and heating for an existing educational building. Dynamic simulation has been performed in TRNSYS Software to calculate the hydrogen production annually at different scenarios. Effects of hydrogen concentration in the fuel mixture on the performance of the proposed CHP system are assessed. Results indicated that utilizing a reasonable roof area can offer approximately 10,000 kg H 2 and 70,000 kg H 2 per year in cases of grid-zero connected and grid 85% connected, respectively. It is revealed that increasing the hydrogen share in fuel mixture from 5% to 30% increases noticeably the hydrogen gas percentage at the SOFC anode inlet and outlet while it has a reverse effect on the H 2 O amount. In addition, the studied increment in hydrogen share could increase 18% of the net output power from the system. Finally, related to the CO 2 emission from the system, it is found that 58% reduction could be achieved by increasing the hydrogen share in the fuel blended. • A new CHP unit by utilisation of green hydrogen and syngas for an educational building is proposed. • Dynamic simulation results prove that grid-zero connected mode can provide 10T hydrogen annually. • Quality of syngas is enhanced by hydrogen injection revealing a positive effect on SOFC performance. • Increasing the share of green hydrogen in the final fuel would increase 18% of total power of the system. • 30% hydrogen injection to syngas can cut the total CO 2 emission from the system by up to 58%. [ABSTRACT FROM AUTHOR]

In this study, we examine a liquid hydrogen (LH 2)-fueled hybrid ship propulsion system (HSPS) consisting of an LH 2 fuel gas supply system (FGSS), a polymer electrolyte membrane fuel cell (PEMFC), and battery systems. The LH 2 -HSPS is analyzed through three dynamic simulations, representing different PEMFC outputs, for a 2-MW-class tugboat. During transient states of LH 2 FGSS, hydrogen temperature changes from 11 to 41 °C at the LH 2 vaporizer outlet. Dynamic simulations considering hydrogen temperature tolerance in the PEMFC system show interruptions of power generation during 1–5 s. In Case 3, where the PEMFC system provides all propulsive power, an energy capacity of 310–1860 kWh is calculated with maximum C-rates of 1C–6C. The average power consumption of the balance of plant in the PEMFC system is 43.64, 27.51, and 44.06 kW for Cases 1–3, respectively. Finally, the battery system's thermal management is well performed for all cases. • The LH 2 -HSPS is designed and modeled for a target ship of a 2-MW-class tugboat. • Dynamic characteristics of the LH 2 FGSS and HSPS are analyzed. • Capacity of the battery system is dependent on the operating mode of the LH2-HSPS. • Relationship between power interruption and H 2 supply temperature is examined. [ABSTRACT FROM AUTHOR]

The hydrogen fuel cell electric vehicle is fueled by the pressure difference in the fueling tank with high-pressure hydrogen compressed at the hydrogen fueling station, and the fueling delay occurs when the pressure difference becomes small. To resolve this, most hydrogen fueling stations minimize fueling time by cascade fueling method by installing two or three banks. Although there are protocols for hydrogen fueling, there are no guidelines for 3-bank operation, so each hydrogen fueling station has different ways to fuel. This study proposes a dynamic simulation model and open-source implementation in Python that can check the temperature and pressure changes of the fueling tank. To implement the n-bank model, we add factors that can be used as operating guidelines for fueling stations, such as supply pressure of the banks and switch moment. Through optimization studies on these factors using simulation models, we propose optimal operation guidelines for fueling stations. [Display omitted] • Development of dynamic simulation model for hydrogen fueling process with n-bank cascade system. • Python open-source simulator that allows users to analyze the simulation results under desired conditions. • Validated model using experimental data for actual fueling process. • Optimizing the fueling process to shorten the fueling time and minimize the fueling energy. • Fueling guidelines for station operators with safety and fast fueling. [ABSTRACT FROM AUTHOR]

• The coolprop thermodynamic equations of state and the implicit fitting method have been investigated for calculating the refrigerants' thermodynamic properties. • A dynamic cascade refrigeration cycle has been developed and simulated with both methods for comparison. • The simulation was 30 times faster with the implicit fitting method than coolprop equations of state. • The implicit fitting method showed high accuracy. Modeling and simulating dynamic and complex energy systems that are composed of a large number of components where every component model is described by mathematical equations can take high computational time. The calculation of the refrigerant thermodynamic properties has a big impact on the computational speed of the model. In an attempt to speed up simulations, two implementation methods for the calculation of refrigerants' thermodynamic properties were investigated, the Coolprop thermodynamic equations of state and the Implicit fitting method. A complex dynamic cascade refrigeration cycle was developed and simulated using the two fluids implementation methods. The advantages and disadvantages of each method were discussed. The results show that using the implicit fitting method instead of Coolprop for the simulations of complex dynamic systems in Dymola will accelerate the simulation by about 30 times. In addition, the implicit method is accurate and offers more flexibility for modeling complex realistic energy systems. [ABSTRACT FROM AUTHOR]

Cumin and eucalyptus essential oils (EOs) are among the most important and widely used EOs with a broad range of applications in the pharmaceuticals, cosmetics, and food industries. The seeds and leaves of cumin (Cuminum cyminum) and eucalyptus (Eucalyptus globulus) plants are processed with extraction techniques to retrieve their EOs, yet certain product specifications need to be met to achieve a high-quality product. Based on the International Organization for Standardization (ISO), the essential oils of cumin and eucalyptus should contain certain amounts of cuminaldehyde and 1,8-cineole to be of acceptable quality. In this study, we design and optimize a dynamic fractional distillation process that enriches cumin and eucalyptus EOs to the ISO standards, with concentrations of 42% cuminaldehyde and 80% of 1,8-cineole achieved for each EO respectively. The dynamic model of this process is simulated via Aspen Plus using data from a pilot-scale fractional distillation unit, and the operating conditions that minimize the operational cost in the simulated environment are identified using the NOMAD algorithm. The optimization results show that the operating cost of standardization processes for cumin and eucalyptus EOs are $0.688/batch and $0.6973/batch, with process efficiencies of 69.56% and 59.77%, respectively. Furthermore, the techno-economic analysis for these two standardization processes showed that the total annualized cost was approximately $510,600 for both processes. [ABSTRACT FROM AUTHOR]

Fine-crystallized micro-structured surfaces have excellent physical and antifatigue properties. However, flexible fabrication of fine-crystallized micro-structured surfaces is still a challenge for current additive and subtractive machining technologies. This study proposes a high-frequency diamond imprinting (HFDI) technology and a principle for generating micro-structured surfaces based on splicing simple geometry shapes. Micro-structured surfaces, such as micro-images with anti-counterfeiting codes, microscopic QR codes and biomimetic surfaces, were successfully machined by HFDI on polycrystalline nickel. The size of subsurface grains is highly reduced from over 30 µm to less than 1 µm, and a fine-crystallized layer with a thickness of 10 µm is formed. In addition, a cross-scale coupling model of HFDI, based on discrete dislocation dynamics, is constructed to realize dynamic simulation of subsurface dislocation motion and to explore fine crystallization mechanisms. This research holds theoretical and practical significance for realizing high performance and high precision machining. [ABSTRACT FROM AUTHOR]

In the chemical and petrochemical industries, an azeotropic mixture of acetone/methanol/butanone/tert-butanol needs to be separated for high-purity products. Following a previous work in which an energy-saving process composed of two extractive dividing-wall columns (EDWCs) was developed for the quaternary system, this paper focuses on the issue of dynamic control for this process. Several control strategies in combined with temperature control, temperature-difference control and composition control are established to maintain the purity of all products in the face of disturbances in feed flow and feed composition. Dynamic simulations demonstrate that a conventional temperature control structure provides very poor control while a control strategy that used three-temperature-difference control for both EDWCs is the most effective. • An effective control strategy is proposed for two extractive dividing-wall columns process of quaternary azeotropic mixtures. • Multiple temperature differences controls are designed to control the process. • A variety of feed disturbances are used to test control strategies. [ABSTRACT FROM AUTHOR]

Strain-based Dynamics (SBD) (Müller et al., 2014) is a well-known method to simulate the deformable models by using Green's strain tensor within the Position-based Dynamics (PBD) algorithm. Similar to the other position-based constraints, SBD performs stable and robust. However, when we transform the base algorithm from PBD to Extended Position-based Dynamics (XPBD), SBD suffers from the cumbersome parameter adjustments and uncontrollable numerical dissipation, which generates highly stiff results. To overcome these limitations, we propose Exponential Strain-based Dynamics (ESBD) which reformulates the Green's strain tensor with an exponential treatment. Our proposed method is less sensitive to the increased numerical dissipation, so it provides vivid simulation of deformable objects with fewer parameter tunings. In order to present the advantages, we compare our method with SBD by using the XPBD method and other well-known techniques. We observe that ESBD improves the hyperelastic behavior of the Green's strain tensor as a projected constraint without altering the underlying XPBD algorithm. Therefore, it is possible to adapt ESBD to the other existing numerical integration and iteration methods. Our proposed method is stable, straightforward to follow and produces high quality dynamic simulations. [Display omitted] • A novel exponential-based formulation of Green's strain tensor is introduced. • Exp. version of the mod. Green's strain tensor by (Müller et al., 2014) is provided. • Strain-based Dynamics (Müller et al., 2014) is adapted to the XPBD algorithm. • Our method produces vivid visual results with fewer parameter tunings. [ABSTRACT FROM AUTHOR]

• We investigated experimentally the discovery of feedback-learning procedures. • In a dynamic business simulation, participants were incentivized to maximize profits. • Webackward-engineered procedures from recorded actions and information requests. • Anumber of participants discovered an effective heuristic learning procedure. • Implementation errors prevented many participants from realizing its full potential. Domain-general learning rules often enable decision makers to learn from outcome feedback which actions tend to achieve a desired goal. However, in novel and complex environments decision makers must explore how to learn, i.e., acquire procedural knowledge of how to elicit and evaluate outcome feedback that will enable them to navigate toward a desired goal despite the vastness of the set of possible policies. Using a dynamic business simulation, this study investigated: (1) whether and how frequently participants discovered an effective procedure to learn from outcome feedback that allowed them to navigate toward a policy that maximizes long-term business profit (and hence their monetary payoff from the experiment), and (2) whether high monetary incentives affected learning procedures and performance. We found that a number of participants discovered an effective learning procedure and succeeded in approximating the optimal policy. In line with the heuristic method, this learning procedure involved a simplification of the search space and the application of domain-general learning rules to this simplified space. Although the decision histories of about half of the participants feature the key aspect of the effective learning procedure—search among the different steady states of the dynamical system—implementation errors prevented many of the participants from realizing the full potential of the learning procedure. We found no evidence to suggest that high monetary incentives affect the effectiveness of learning. Overall, the study illustrates that a "prepared mind" can discover new, effective learning procedures, although their initial implementation may require substantial refinement. [ABSTRACT FROM AUTHOR]

High-entropy materials are considered to be born with lattice distortion, which is still lack of comprehensive investigation in rare earth silicates to date. In this paper, we confirmed the existence of lattice distortions in high-entropy rare-earth silicates via experiments and molecular dynamic simulations. The effects of the lattice distortion on the thermophysical properties are elucidated. Simulation results indicate the lattice distortion is present in both cation and anion sublattice, leading to the compressing and stretching of atomic bond as well as fluctuation of atomic bond strength. Accordingly, lattice distortion in the Si and O sublattice is also verified by the Raman spectra. Furthermore, the thermal conductivity of high-entropy rare earth silicates remarkably reduces and exhibits glass-like behavior, which is confirmed by experiments in cooperation with molecular dynamic simulations. Simulation also reveals that the lifetimes and group velocities of vibrational modes are significantly reduced by lattice distortion, which result in the reduction of overall thermal conductivity of high-entropy rare-earth silicates. [ABSTRACT FROM AUTHOR]

Ammonia is a kind of carbonless alternative fuel with great research foresight. Improving the burning velocity of NH 3 and studying the reduce of nitrogen oxides have far-reaching significance for the effective utilization of ammonia. This paper mainly studies the characteristics of three different mixtures (NH 3 :H 2 = 1:1, NH 3 :H 2 :CO = 2:1:1, NH 3 :CO = 1:1) in closed tubes under different equivalent ratios of Ф (0.7–1.4), and use chemkin software to simulate the laminar burning velocity under different experimental conditions and at high temperature (298–650 K) and high pressure (1–10 at m), which carry out kinetic analysis and the related exploration of its nitrogen oxide emissions. The results show as follows: (1) In the closed pipe, the flame propagation speed of NH 3 /H 2 /air is the largest, when the equivalent ratio is 1.1, the flame propagation speed of three different mixtures is the highest, the overpressure phenomenon is the most obvious. and the overpressure and temperature are the highest in the pipe. (2) The symmetrical shape of the pipe changes the direction of the flame flow, creating an interesting turbulent flow that resembles a halberd. (3) Replacing half NH 3 fuel of NH 3 /air mixture with H 2 is mainly due to the chemical effect of H 2 leading to the increase of LBV, while replacing half NH 3 fuel of NH 3 /air mixture with CO is mainly due to the thermal effect leading to the increase of LBV. The promotion effect of elevated temperature is mainly due to the contribution thermal effect and chemical effect. For NH 3 /H 2 /air, chemical effect is the main component of promotion effect of elevated temperature. For NH 3 /CO/air mixture, the promotion effect of elevated temperature, which is more the influence of thermal effect. The inhibitory effect of initial pressure is the contribution of chemical effect. (4) High temperature promoted the formation of NO, while high pressure inhibited it. • The combustion characteristics of NH 3 /H 2 /air, NH 3 /CO/air, NH 3 /H 2 /CO/air in a closed pipe are discussed. • The shape of the pipe changes the direction of flame flow and forms an interesting phenomenon. • The different temperature compensation methods are used. • The kinetic analysis of elevated temperature and pressure. [ABSTRACT FROM AUTHOR]

To describe the physical principles of the vortex effect to better understand its applicability in minimally invasive percutaneous nephrolithotomy (MIP) procedures. Two acrylic phantom models were built based on the cross-sectional area (CSA) ratio of a MIP nephroscope and access sheaths (15/16F and 21/22F MIP-M, Karl Storz). The nephroscope phantom was 10 mm in diameter. The access sheaths had diameters of 14 mm (CSA ratio: 0.69) and 20 mm (CSA ratio: 0.30). The models were adapted to generate hydrolysis, and hydrogen bubbles enhanced flow visualization on a green laser background. After calibration, the experimental flow rate was set to 12.0 mL/s. Three 30-second trials assessing the flow were performed with each model. Computational fluid dynamic simulations were completed to determine the speed and pressure profiles. In both models, as the incoming fluid from the nephroscope phantom attempted to move toward the collecting system, a stagnation point was demonstrated. No fluid entered the collecting system phantom. Utilizing the 14 mm sheath, we observed a random generation of several vortices and a pressure gradient (PG) of 114.4 N/m2 between the nephroscope's tip and stagnation point. In contrast, examining the 20 mm sheath revealed a significantly smaller PG (19.4 N/m2) and no noticeable vortices were noted. The speed of the fluid and equipment geometry regulate the PG and the vortices field, which are responsible for the production of the vortex effect. Considering the same flow rate, a higher ratio between the CSA of the nephroscope and access sheath results in improved efficacy of the vortex effect. [ABSTRACT FROM AUTHOR]

The dynamic of hypervelocity projectile impacting inflatable multilayer flexible membrane structure is studied in this paper. The velocity increment of the inflatable multilayer flexible membrane structure under hypervelocity impact comes from two parts. One is the acceleration caused by the pulling of the membrane when the hypervelocity projectile is in direct contact with the membrane, and the other is the acceleration provided by the reverse impulse caused by the gas leakage in the inflatable structure. The hypervelocity projectile will be decelerated in the impact process, and finally fly with the accelerated multilayer flexible membrane structure at the same velocity, which means that the projectile is captured by the membrane structure. According to the above process, the influence of the mechanical property parameters of the flexible membrane on the structural parameters of the multi-layer flexible membrane can be calculated, which can be used to guide the engineering design. Finally, the hypervelocity impact process is verified by the numerical simulation. • Space soft capture method achieved through flexible inflatable membrane structure. • Hypervelocity impact dynamics of flexible inflatable membrane structure. • Verify the dynamic process of hypervelocity impact using numerical simulation. • The influence of membrane mechanical properties on the parameters of the structure. [ABSTRACT FROM AUTHOR]

Chitin deacetylase (CDA) is a promising biocatalyst for synthesizing glucosamine (GlcN), widely used in food and biomedical industries. The main issue limiting its industrial application is its instability. In this study, disulfide bridges were used to enhance the thermostability of Cyclobacterium marinum chitin deacetylase (CmCDA), which specifically and efficiently hydrolyzes N- acetylglucosamine (GlcNAc) to GlcN. Compared to the wild-type CmCDA, variants S44C/D68C and T138C/W279C exhibited less residual activity, whereas variant A58C/F133C demonstrated a 57% improvement after thermo-treatment at 50 °C. At 50 °C, the half-life value of variant A58C/F133C was 2.6 times that of the wild-type, and half-inactivation temperature T 30 50 was a 7.5 °C higher than that of the wild-type. Dynamic simulation (MD) analysis was used to explain the improved thermostability of variant A58C/F133C. After 48 h, A58C/F133C produced approximate 1.23-fold of GlcN. This study preliminarily investigated the effect of disulfide bridge in thermostable chitin deacetylase and suggested a feasible way to improve the thermostability of chitin deacetylases, encouraging their use in biocatalytic glucosamine synthesis. [Display omitted] • Structure and semi-rational design-based mutation were performed to engineer chitin deacetylase. • Mutant A58C/F133C showed 2.6-fold increase in half-life at 50 °C. • MD simulation demonstrated the mutant A58C/F133C had more stable active structure. • Efficient preparation of GlcN using mutant A58C/F133C was feasible. [ABSTRACT FROM AUTHOR]

A density functional study of the electronic structures of C 6 O 6 M 6 (M = Li, Na) clusters, as well as their potentials for dihydrogen storage, have been performed by two methods. Molecular dynamic simulations confirm that both clusters are thermodynamically stable. Calculations reveal that C 6 O 6 Li 6 /C 6 O 6 Na 6 can adsorb up to 36/38H 2 molecules with a gravimetric uptake capacity of 26.10/19.90 wt%, exceeding the goal (5.5 wt%) set by the US Department of Energy (DOE). The adsorption energies of H 2 on C 6 O 6 Li 6 and C 6 O 6 Na 6 are in the range of 0.093–0.119 eV and 0.112–0.228 eV, respectively. The interactions of C 6 O 6 M 6 (M = Li, Na) with H 2 molecules are analyzed by a variety of electronic structure methods. Thermo-chemistry calculations indicate two H 2 in C 6 O 6 Li 6 (H 2) 36 and fourteen H 2 in C 6 O 6 Na 6 (H 2) 38 can be readily adsorbed at 77 K and desorbed at 298.15 K under atmospheric pressure, corresponding to the maximal reversible hydrogen storage densities are 2.11 wt% and 8.38 wt%, respectively. Higher pressure can improve the maximal reversible hydrogen storage abilities. Atom density matrix propagation (ADMP) molecular dynamic simulations indicate that H 2 molecules are substantially and strongly bound at 77 K and get efficiently released at elevated temperature (300 K). The (C 6 O 6 M 6) 2 (M = Li, Na) dimers can also efficiently adsorb multiple H 2 molecules with high gravimetric density and reversible average adsorption energy. [Display omitted] • The cluster C 6 O 6 Li 6 /C 6 O 6 Na 6 can adsorb 36/38 hydrogen molecules. • The H 2 gravimetric density of C 6 O 6 Li 6 /C 6 O 6 Na 6 is 26.10/19.90 wt%. • The average adsorption energies of H 2 on C 6 O 6 Li 6 /C 6 O 6 Na 6 is in the range of 0.093/0.112–0.119/0.228 eV/H 2. • H 2 molecules are strongly bound at 77 K and get efficiently released at elevated temperature (300 K). • The (C 6 O 6 Li 6) 2 /(C 6 O 6 Na 6) 2 dimer can adsorb 47/50 hydrogen molecules with the gravimetric density of 19.67/14.04 wt%. [ABSTRACT FROM AUTHOR]

Fouling during membrane emulsification due to biomolecule adsorption is still a drawback for broader applicability and a better holistic understanding is needed. This study aimed to investigate the fouling effect on the membrane and the enzyme being modified due to adsorption. Therefore, a lipase solution with varying concentrations and pH was filtered through a silica-based membrane. The degree of adsorption, membrane properties (microstructure and phase wetting), and enzymatic characteristics (conformation and activity) were evaluated. For insights on the molecular level, molecular dynamic simulations of the conformational changes of lipase caused by adsorption were performed. Regarding the membrane, an increase in lipase concentration increased the adsorption leading to higher fouling and decreased wetting implying a higher hydrophobicity of the membrane. Additionally, SEM showed that the pH of the lipase solution modified the microstructure of the foulant layer. Regarding the impact on the lipase, molecular dynamic simulations revealed an increase in the hydrophobic surface area, a rearrangement of the C-alpha atoms of the protein backbone, and an increase in the radius of gyration. Despite leading to enzyme mass loss, both the secondary structure and the activity showed no significant differences after processing, which might be due to the reversible adsorption. [Display omitted] • Lipase concentration, but not pH, affected the occurrence of membrane fouling. • Change in electrostatic interactions due to pH variation resulted in differences in microstructure of adsorbed lipase layer. • MD simulation showed structural rearrangement and exposure of hydrophobic groups causing hydrophobization of membrane surface. • Nevertheless the adsorbed mass, the secondary structure and enzymatic activity of lipase in the permeate remained unmodified. [ABSTRACT FROM AUTHOR]

VhChiP is a chitooligosaccharide-specific porin identified in the outer membrane of Vibrio campbellii type strain American Type Culture Collection BAA 1116. VhChiP contains three identical subunits, and in each subunit, the 19-amino acid N-terminal segment serves as a molecular plug (the “N-plug”) that controls the closed/open dynamics of the neighboring pores. In this study, the crystal structures of VhChiP lacking the N-plug were determined in the absence and presence of chitohexaose. Binding studies of sugar–ligand interactions by single-channel recordings and isothermal microcalorimetry experiments suggested that the deletion of the N-plug peptide significantly weakened the sugar-binding affinity due to the loss of hydrogen bonds around the central affinity sites. Steered molecular dynamic simulations revealed that the movement of the sugar chain along the sugar passage triggered the ejection of the N-plug, while the H-bonds transiently formed between the reducing end GlcNAc units of the sugar chain with the N-plug peptide may help to facilitate sugar translocation. The findings enable us to propose the structural displacement model, which enables us to understand the molecular basis of chitooligo-saccharide uptake by marine Vibrio bacteria. [ABSTRACT FROM AUTHOR]

This paper introduces a dynamic simulation of a biped robot with 12 degrees of freedom (DoF) using the Unit Vector approach. The research focuses on characterizing the 12 DoF biped robot as a dynamic model with a floating base, involving multiple rigid bodies. The robot's representation adopts a floating-base tree structure that interacts with its environment through contact points. The dynamic analysis of the 12 DoF biped robot is carried out using the Newton-Euler (N-E) recursive method. This method is employed to compute joint acceleration, inertia matrices, and forces and torques acting on all links and joints, utilizing the Unit Vector approach.The paper provides a comprehensive, step-by-step explanation of the dynamic analysis process for the 12 DoF biped robot using the Newton-Euler recursive algorithm with the Unit Vector approach. Dynamic simulations are conducted in MATLAB, encompassing both the fixed and swing leg motions during walking. The computed results elucidate the dynamic behavior of the 12 DoF biped robot throughout its walking cycle. [ABSTRACT FROM AUTHOR]

Thermal Cycling Absorption Process (TCAP) is an important method to separate hydrogen isotopes for the production and engineering application of tritium. There are so many influencing factors that it is difficult to fully understand the influence mechanisms only through experiments. A new simulation model of TCAP was developed. Using the simulation model, the influencing trend and optimized value of parameters of initial feeding process and total reflux mode in TCAP are obtained as follows. (1) The temperatures of initial feeding and the cold cycle are not the lower the better as commonly assumed but exists an optimal value of 30 °C in initial feeding and -20 °C in the cold cycle. (2) The heating rate and cooling rate also exist optimal values of 45 °C/min and 55 °C/min (3) Lower feeding rate is conducive to a better separation effect of hydrogen isotopes. (4) Increasing the reflux ratio benefits the enrichment of heavy hydrogen isotope at the product side but not the light hydrogen isotope at the tail side. (5) It needs more cycles to achieve the same isotope abundance in D/T separation than H/D separation and the separation degree of hydrogen isotopes exists a maximum value after multiple cycles. The findings can provide references for the process optimization and the device design of TCAP, and also can shed new light on the understanding of the basic physical and chemical process of TCAP. A new simulation model of TCAP was developed. Compared with commercial simulation softwares, device parameters and process conditions of TCAP can be flexibly considered in the numerical model. [Display omitted] • A new simulation model of TCAP was developed. • Device parameters and process conditions of TCAP can be flexibly assessed. • Optimized parameters in initial feeding process and total reflux mode was obtained. • Temperatures of cold cycles exist optimum values, not as commonly assumed. [ABSTRACT FROM AUTHOR]

In this work, a novel approach based on the multistage optimal control formulation of the control loop selection problem is introduced. Currently, state-of-the-art approaches for controller loop design have been focused on data that yield only the pairings between input-output variables, and are not able to incorporate path and end-point constraints. Thus, they only produce the optimal loops for control purposes, without the simultaneous consideration of their optimal tuning. This formulation overcomes these drawbacks by producing an automated integrated solution for the task of control loop design, which also obviates the need for any form of combinatorial optimisastion to be used. To illustrate the procedure, as well as the advantages of the proposed scheme, different practical case studies are discussed and the results compared with those obtained with standard controller loop selection methods and their tuning. The results of the proposed approach show improved performance over previous methodologies found in the literature. Furthermore, the framework is extended to the selection of the control loops that must obey path and end-point constraints imposed by the underlying dynamical process. This task is usually difficult for classical methods, which violate them or exhibit underdamped response in some cases. • Novel PI controller tuning and control loop selection. • Inclusion of general path and point constraints. • Optimal control problem formulation with continuous variables. • Implementation possible in standard dynamic simulation packages. [ABSTRACT FROM AUTHOR]

This paper aims at optimizing the energy performance of an innovative integrated collector-storage solar water heater (ICSSWH) prototype. The system incorporates a high-vacuum gap, which significantly reduces convective thermal losses, and a serpentine absorber system coated with a low-E layer to minimize radiative thermal losses. The methodology is based on a detailed dynamic simulation model, implemented in the MatLab environment, suitable conceived to accurately predict the energy performance and economic profitability of the ICSSWH under various weather conditions and energy market prices. This approach aims to initially identify the most influential geometrical, thermophysical and optical parameters that impact the energy performance of the system through the assessment of different objective functions. After identifying the most influential parameters, the range of existence with the interval step for each variable is defined, and the optimization procedure is conducted to determine the optimal set of variables that maximize/minimize the selected objective functions. To demonstrate the effectiveness of the proposed methodology, a proof of concept was conducted to optimize the energy performance of novel ICSSWH by considering nineteen parameters with the aim of maximizing/minimizing three different objective functions. The results of this analysis yielded various sets of optimised parameters for the ICSSWH. Therefore, by implementing the set of optimised parameters into the dynamic simulation model, the energy performance of the optimised and non-optimised ICSSWH collectors was evaluated in 42 different weather zones and compared to a reference case scenario. [ABSTRACT FROM AUTHOR]

• A framework for a hybrid terramechanics modelling method is presented. • The method involves using ML to augment existing semi-empirical models. • Model presented in a general way that can be applied to any semi-empirical model. • Method applied to a blade simulation with the Fundamental Earthmoving Equation. • Method applied to a wheel simulation with the Bekker-Wong terramechanics formulation. The field of terramechanics focuses largely on two types of simulation approaches. First, the classical semi-empirical methods that rely on empirically determined soil parameters and equations to calculate the soil reaction forces acting on a wheel, track or tool. One major drawback to these methods is that they are only valid under steady-state conditions. The more flexible modelling approaches are discrete or finite element methods (DEM, FEM) that discretize the soil into elements. These computationally demanding approaches do away with the steady state assumption at the cost of including more model parameters that can be difficult to accurately tune. Model-free approaches in which machine learning algorithms are used to predict soil reaction forces have been explored in the past, but the use of these models comes at the cost of the valuable insight that the semi-empirical models provide. In this work, we presume that in a dynamic simulation, the soil reaction forces can be divided into a steady state component that can be captured using semi-empirical models and a dynamic component that cannot. We propose an augmented modelling approach in which a neural network is trained to predict the dynamic component of the reaction forces. We explore how this theory can be applied to the simulation of a soil-cutting blade using the Fundamental Earthmoving Equation and of a wheel driving over soft soil using the Bekker wheel-soil model. [ABSTRACT FROM AUTHOR]

• A dynamic model of transcritical CO 2 multi-ejector refrigeration system is developed. • The dynamic responses of the system under different disturbances are simulated. • The optimal ejector combination maximizes the system COP and pressure lift ratio. • A wide working condition adaptive regulation strategy is proposed. This paper presents a dynamic model of transcritical CO 2 refrigeration system with multi-ejector which is developed based on the real CO 2 properties and considering the internal transonic flow, phase change and choking, and its predictions are in good agreement with experimental data from the literature. The transient response of the system is studied by adjusting the speed of compressor, water flow of heat exchanger, opening of expansion valve and combination of ejector as disturbance conditions. The presented results show that the developed dynamic model has similar response rules with the same type of system. Changes of cooling water flow of gas cooler and chilled water flow of flooded evaporator can cause significant response of other pressures in the system except low-temperature evaporator, and can regulate the cooling and heating load to some extent. Opening of medium and low temperature expansion valve plays a decisive role in the system's medium and low temperature refrigeration capacity respectively, and the low-temperature expansion valve is the only regulation means of the low-temperature cooling capacity. Optimal operating combination of multi-ejector maximizes the system performance and ejector pressure lift ratio. Furthermore, the optimal ejector combination of the system under the refrigeration capacity of 75∼115 kW is studied and compared, a control strategy of adjusting ejector combination by "nozzle mass flow rate" is put forward to adapt to the high-performance operation of the system under different loads. Under the research conditions, the optimal ejector combination satisfies that the nozzle mass flow rate is stable in 0.066∼0.070 kg·s-1. [Display omitted] [ABSTRACT FROM AUTHOR]

• Conversion of a DHN to diversified and decentralized renewable supply. • Fully physical digital twin of real DHN used to compare five renewable scenarios. • Implementation of up to 11 different generation and storage technologies at once. • Thermal energy storages with high charging/discharging power are essential. • Results show that at least 98 % renewable supply is possible. Due to the tremendous effects of climate change, the goal of a climate-friendly energy supply has developed into the main task of the energy sector. Today climate neutrality is a central issue at social, political and economic levels. It is a sector coupling issue, requiring renewable energies in electricity, mobility and heat supply. While the heat sector contributes the largest share to final energy demand of German municipalities, it is also the sector for which the path towards climate neutrality will be most challenging. This study presents pathways for large cities for the transition from fossil to renewable heat supply based on the example of Rostock. A detailed, fully-physical simulation model for Rostock's district heating was developed considering different potential heat sources including heat pumps, industrial and process heat, incineration of sewage sludge, waste and solid biomass as well as geothermal and solar thermal plants. Additionally, thermal energy storages have been integrated into the model. The study highlights the importance of simulation models in evaluating the feasibility of energy systems and emphasizes the need for incorporating detailed information in these models to obtain accurate results. Multiple scenarios have been investigated in order to analyse the interplay of heat generation, storage and the annual course of heat consumption. Five final concepts were derived meeting the requirement of climate-neutral heat supply. Although the results show that each variant has advantages and disadvantages, heat generators that make technical and economic sense in all cases were identified. The implementation of these is recommended. [ABSTRACT FROM AUTHOR]

The contactless electromagnetic de-tumbling method does not have physical contact with the uncooperative space targets and can avoid generating new space debris. Due to pollution-free and high safety performance advantages, this method has a tremendous prospect in the application of de-tumbling the uncooperative space targets. In this paper, an improved arc-linear electromagnetic device and its corresponding de-tumbling method are presented based on the principle of electromagnetic eddy current, which is mainly used for the uncooperative space targets. The analytical model of the electromagnetic device is obtained by introducing the Carter and Russel-Norsworthy coefficients and validated by the finite element method (FEM). Then, the effect on the de-tumbling torque with different electromagnetic parameters is further analyzed. Finally, the three-dimensional dynamic simulation of the uncooperative space target is carried out. The results show that the uncooperative space target can be de-tumbled in a short time by the proposed contactless electromagnetic de-tumbling device. [ABSTRACT FROM AUTHOR]

This investigation analyses the 3D performance of two optimal front wing designs according to the Federation Internationale de l'Automobile 2021 regulations. These regulations imply a 3D five-element front wing, with ground effect and more than 30 design parameters and geometry constrains in practice, which has not been studied before in the literature. The two optimal front wing designs were obtained by parametric optimisation with sampled Kriging interpolation surrogates and a posteriori adjoint-based design refinement. The optimal front wings have been tested on 3D Computational Fluid Dynamic simulations to analyse the generated downforce and flow interaction with the front wheels and brake ducts, as well as the reproduction of influential vortices. Although the parametric design achieved a slightly better downforce-to-drag ratio, the adjoint-based design exhibited a greater ground suction effect, lower pressure distribution on the tire treads, and some deviation of the Y250 vortices to the wheel, which affected the flow over the wheel&brake ducts. This work demonstrated that quick improvements can be achieved starting from 2D analysis and running 3D simulations of relevant parts of the car, which is unaffordable to date for direct 3D simulation in a design space reduced to 17 dimensions and constrained by regulations. [ABSTRACT FROM AUTHOR]

This paper presents the design, modelling and experimental verification of a damping joint for application to miniature space docking mechanisms. The joint design is based on deformable elastomeric elements, thus avoiding any sliding or contact between moving components. Numerical FEM simulations have been conducted in order to quantify the joint mechanical characteristics (rigidity and damping coefficient) as a function of the main design parameters (geometry, material, assembly). The obtained parametric relations provide an estimate of the joint characteristics based on the selected design. An equivalent visco-elastic model is developed and implemented in dynamic simulations. The results of the experimental evaluation of the joint design provide a validation of the developed models and prove the advantage of adopting damping joints in docking applications between small satellites, like reduced contact loads and enhanced damping. • Passive damping joint to manage the contact loads between miniature docking interfaces. • Simple solid-state design with sizing relations. • Laboratory validation of force reduction and energy dissipation concepts. • Experimental validation of the mathematical models. [ABSTRACT FROM AUTHOR]