The aim of the study is to simulate actual operation of an elevator. First, it designed elevator scheduling algorithm for control ing operation of the elevator;second, it simulated elevator operation by the use of obj...The aim of the study is to simulate actual operation of an elevator. First, it designed elevator scheduling algorithm for control ing operation of the elevator;second, it simulated elevator operation by the use of object-oriented programming language, in which double buffering technology was used to solve the problem of elevator pictures flicker at refreshing; final y, test correctness and rationality of the system.展开更多
Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of...Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments.Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energysaving potential under varying conditions.Results show that increasing the AC setpoint from 25○C to 27○C,combined with ceiling fan operation,reduced power consumption by 10%,achieving significant energy savings.Survey data confirmed that 85%of participants reported consistent thermal sensations across all conditions,with ceiling fans effectively compensating for higher setpoints through enhanced air circulation.CFDsimulations revealed that mediumspeed ceiling fan operation produced the most uniformairflowdistribution,with an average air velocity of 0.45 m/s,and minimized temperature variations,ensuring balanced thermal conditions.Temperature analysis showed a reduction in hotspots and cold zones,maintaining an average temperature deviation of less than±0.5○C.Predicted Mean Vote(PMV)evaluations at a 27○C setpoint indicated improved thermal comfort,with average PMV values around−0.3,corresponding to a“neutral”thermal sensation.These findings demonstrate the effectiveness of integrating ceiling fans with HVAC systems in achieving energy efficiency and occupant comfort,offering a sustainable approach to reducing AC energy consumption in office environments.展开更多
To explore atomic-level phenomena in the Cu-Ni-Sn alloy,a second nearest-neighbor modified embedded-atom method(2NN MEAM)potential has been developed for the Cu-Ni-Sn system,building upon the work of other researchers...To explore atomic-level phenomena in the Cu-Ni-Sn alloy,a second nearest-neighbor modified embedded-atom method(2NN MEAM)potential has been developed for the Cu-Ni-Sn system,building upon the work of other researchers.This potential demonstrates remarkable accuracy in predicting the lattice constant,with a relative error of less than 0.5%when compared to density functional theory(DFT)results,and it achieves a 10%relative error in the enthalpy of formation compared to experimental data,marking substantial advancements over prior models.The bulk modulus is predicted with a relative error of 8%compared to DFT.Notably,the potential effectively simulates the processes of melting and solidification of Cu-15Ni-8Sn,with a simulated melting point that closely aligns with the experimental value,within a 7.5%margin.This serves as a foundation for establishing a 2NN MEAM potential for a flawless Cu-Ni-Sn system and its microalloying systems.展开更多
This study employs the Smoothed Particle Hydrodynamics(SPH)method to develop a computational fluid dynamics(CFD)model for analyzing the interaction between rogue waves and mooring systems.Four floating body configurat...This study employs the Smoothed Particle Hydrodynamics(SPH)method to develop a computational fluid dynamics(CFD)model for analyzing the interaction between rogue waves and mooring systems.Four floating body configurations are investigated:(1)dual rectangular prisms,(2)rectangular prism–sphere composites,(3)sphere–rectangular prism composites,and(4)dual spheres.These configurations are systematically evaluated under varying mooring conditions to assess their hydrodynamic performance and wave attenuation capabilities.The model accurately captures the complex fluid–structure interaction dynamics between moored floating breakwaters and incident wave fields.Among the configurations,the dual rectangular prism system demonstrates superior performance in both wave dissipation and mooring force reduction.Under conditions involving dual wave makers,the influence of floating body shape and number on wave height is found to be minimal.However,dual-body arrangements consistently outperform single-body setups in terms of both energy dissipation and structural stability.From a cost-efficiency perspective,the configuration comprising two rectangular prisms connected via a single mooring system offers significant advantages in material usage and deployment feasibility.展开更多
This paper presents the design and ground verification for vision-based relative navigation systems of microsatellites,which offers a comprehensive hardware design solution and a robust experimental verification metho...This paper presents the design and ground verification for vision-based relative navigation systems of microsatellites,which offers a comprehensive hardware design solution and a robust experimental verification methodology for practical implementation of vision-based navigation technology on the microsatellite platform.Firstly,a low power consumption,light weight,and high performance vision-based relative navigation optical sensor is designed.Subsequently,a set of ground verification system is designed for the hardware-in-the-loop testing of the vision-based relative navigation systems.Finally,the designed vision-based relative navigation optical sensor and the proposed angles-only navigation algorithms are tested on the ground verification system.The results verify that the optical simulator after geometrical calibration can meet the requirements of the hardware-in-the-loop testing of vision-based relative navigation systems.Based on experimental results,the relative position accuracy of the angles-only navigation filter at terminal time is increased by 25.5%,and the relative speed accuracy is increased by 31.3% compared with those of optical simulator before geometrical calibration.展开更多
A state-of-the-art review is presented of mathematical manoeuvring models for surface ships and parameter estimation methods that have been used to build mathematical manoeuvring models for surface ships. In the first...A state-of-the-art review is presented of mathematical manoeuvring models for surface ships and parameter estimation methods that have been used to build mathematical manoeuvring models for surface ships. In the first part, the classical manoeuvring models, such as the Abkowitz model, MMG, Nomoto and their revised versions, are revisited and the model structure with the hydrodynamic coefficients is also presented.Then, manoeuvring tests, including both the scaled model tests and sea trials, are introduced with the fact that the test data is critically important to obtain reliable results using parameter estimation methods. In the last part, selected papers published in journals and international conferences are reviewed and the statistical analysis of the manoeuvring models, test data, system identification methods and environmental disturbances used in the paper is presented.展开更多
The spatiotemporal characterization of plume sedimentation and microorganisms is critical for developing plume ecological monitoring model.To address the limitations of traditional methods in obtaining high-quality se...The spatiotemporal characterization of plume sedimentation and microorganisms is critical for developing plume ecological monitoring model.To address the limitations of traditional methods in obtaining high-quality sediment,a novel sampling system with 6000 m operational capability and three-month endurance was developed.It is equipped with three sediment samplers,a set of formaldehyde preservation solution injection devices.The system is controlled by a low-power,timing-triggered controllers.To investigate low-disturbance rheological mechanisms,gap controlled rheological tests were conducted to optimize the structural design of the sampling and sealing assembly.Stress-controlled shear rheological tests were employed to investigate the mechanisms governing yield stress in sediments under varying temperature conditions and boundary roughness.Additionally,the coupled Eulerian-Lagrangian(CEL)method and sediment rheological constitutive models were employed to simulate tube-soil interaction dynamics and sediment disturbance.The radial heterogeneity of sediment disturbance and friction variation of the sampling tube were revealed.The tube was completely“plugged”at a penetration depth of 261 mm,providing critical data support to the penetration depth parameters.The deep-sea pressure test and South China Sea field trials demonstrated the system’s capability to collect and preserve quantitative time-series sediment samples with high fidelity.展开更多
In order to support the physical research on the EAST tokamak,a new positive ion source with designed beam energy of 120 keV was proposed to be developed.Accelerator structure is one of the key components of the ion s...In order to support the physical research on the EAST tokamak,a new positive ion source with designed beam energy of 120 keV was proposed to be developed.Accelerator structure is one of the key components of the ion source.Through the finite element analysis method,the electrostatic analyses of insulators and grid plates were carried out,the material and structure parameters of insulators were determined.The maximum electric field around each insulator is about 4 kV/mm,and the maximum electric field between grids is about 14 kV/mm,which can meet the 120 keV withstand voltage holding.The insulation system for the positive ion source accelerator with 120 keV is designed,and the connection and basic parameters of insulators and support flanges are analyzed and determined.展开更多
This paper investigates the selective maintenance o systems that perform multi-mission in succession. Selective maintenance is performed on systems with limited break time to improve the success of the next mission. I...This paper investigates the selective maintenance o systems that perform multi-mission in succession. Selective maintenance is performed on systems with limited break time to improve the success of the next mission. In general, the duration of the mission is stochastic. However, existing studies rarely take into account system availability and the repairpersons with different skill levels. To solve this problem, a new multi-mission selective maintenance and repairpersons assignment model with stochastic duration of the mission are developed. To maximize the minimum phase-mission reliability while meeting the minimum system availability, the model is transformed into an optimization problem subject to limited maintenance resources. The optimization is then realized using an analytical method based on a self-programming function and a Monte Carlo simulation method, respectively. Finally, the validity of the model and solution method approaches are verified by numerical arithmetic examples. Comparative and sensitivity analyses are made to provide proven recommendations for decision-makers.展开更多
Topological invariants are crucial for characterizing topological systems.However,experimentally measuring them presents a significant challenge,especially in non-Hermitian systems where the biorthogonal eigenvectors ...Topological invariants are crucial for characterizing topological systems.However,experimentally measuring them presents a significant challenge,especially in non-Hermitian systems where the biorthogonal eigenvectors are often necessary.We propose a general approach for measuring the topological invariants of one-dimensional non-Hermitian systems,which can be derived from the spin textures of right eigenstates.By utilizing a dilation method,we realize a non-Hermitian system without chiral symmetry on a two-qubit nuclear magnetic resonance system and measure the winding number associated with the eigenstates.In addition to examining the topology of the eigenstates,our experiment also reveals the topological structure of the energy band,which differs from that in chiral systems.Our work paves the way for further exploration of complex topological properties in non-Hermitian systems without chiral symmetry.展开更多
Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot ...Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot water.In order to reduce fossil energy use in the household sector,great efforts are being made to design new energy concepts that expand the use of renewable energies to supply electricity andheat.Onepossibility is toconvertparts of the natural gas grid to a hydrogen-based gas grid to deliver and store energy for urban quarters of buildings,especially with older building stock where electrification of heat via heat pumps is difficult due to technical,acoustical,and economic reasons.A comprehensive dataset was generated by a bottom-up analysis with open governmental and statistical data to determine regional building types regarding energy demand,solar potential,and existing grid infrastructure.The buildings’connections to the electricity,gas,and district heating networks are considered.From this,a representative sample dataset was chosen as input for a newly developed energy system model based on energy flow simulation.The model simulates the interaction of hydrogen generation(HG)(from excess solar energy by electrolysis),storage in a metal-hydride storage(MHS)tank,and hydrogen use in a connected fuel cell(FC),forming a local PVPtGtHP(Photovoltaic Power-to-Gas-to-Heat-and-Power)network.Next to the seasonal hydrogen storage path(HSP),a battery will complete the system to forma hybrid energy storage system(HESS).Paired with seasonal time series for PV power,electricity and heat demand,and a model for connection to grid infrastructure,the simulation of different hydrogen applications and MHS placements aims to analyze operating times and energy share of the systems’equipment and existing infrastructure.The method to obtain the data set together with the simulationmodel presented can be used by energy planners for cities,communities,and building developers to analyze the potentials of a quarter or region and plan a transition towards a more energy-efficient and sustainable energy system.展开更多
With the major developments that occurred during the past 40 years in the geotechnical engineering field,the usage of reinforcements in soils has been very common to improve the ultimate bearing capacity and reduce th...With the major developments that occurred during the past 40 years in the geotechnical engineering field,the usage of reinforcements in soils has been very common to improve the ultimate bearing capacity and reduce the footing settlements.These reinforcements consist of geogrids,geotextiles,geocells,etc.,all of which are in the geosynthetic family.Among these geosynthetic families,geocell performs better in soil-reinforced beds.In this study,we proposed the nine types of bioinspired geocells to improve the soil beds.For this purpose,a total of twenty numerical models were calculated via FLAC3D after validating the la-boratory model tests in the literature.The numerical results demonstrated that,except for the circular type,the performance of other geocell forms regarding increased bearing capacity was nearly identical.Regarding diffusion angles,only the circular and honeycomb geocells exhibited larger diffusion angles.The opening pocket diameter more significantly influenced the stress and strain of geocells.Geocells with nearly circular shapes,such as circular,honeycomb,hexagonal,and square,typically demonstrated higher confining stresses within the geocell walls.Conversely,for shapes that deviate from the circular form,such as dia-mond,re-entrant,and double V-shaped designs,the irregularity of the pocket shape could cause an uneven distribution of confining stresses,potentially leading to higher normal deformations at some specific areas and stress concentration at the wall joints.展开更多
A thermionic gun is endowed with a long bunch tail,which presents challenges for the compact terahertz free electron laser(FEL)facility at the Huazhong University of Science and Technology.Owing to a large energy spre...A thermionic gun is endowed with a long bunch tail,which presents challenges for the compact terahertz free electron laser(FEL)facility at the Huazhong University of Science and Technology.Owing to a large energy spread,the tail particles do not contribute to the radiation.In the original design,an x-direction slit is used in the dispersive section of the transport line to remove the tail particles.This paper presents an improved scheme to remove the tail by introducing an RF beam chopper system at the exit of the electron gun,to prevent a significant number of tail particles from entering the linac.The facility remains compact while effectively removing the tail of the bunch.The parameters of the beam chopper system are designed.Bunch parameters and radiation performance are analyzed via a start-to-end simulation.The findings indicate that 43%of the particles can pass through the beam chopper system for subsequent acceleration and transport,which saves the RF power,reduces beam loss in the linac,reduces background noise,and suppresses the sideband instability.Simultaneously,the beam chopper system causes an increase in beam emittance,energy spread,and an offset in the center of the bunch.These effects can be mitigated by a solenoid,linac,and steering coils.The simulation results for the FEL show that the micro-pulse energy is greater than 1.1μJ in the frequency range of 2.8-9.7 THz,and the maximum micro-pulse energy is 1.28μJ.展开更多
The prebiotic effects of hyaluronan(HA)are widely recognized,contributing to improved gut health and immune modulation.Despite its extensive use as dietary supplement,the specific interactions between HA oligosacchari...The prebiotic effects of hyaluronan(HA)are widely recognized,contributing to improved gut health and immune modulation.Despite its extensive use as dietary supplement,the specific interactions between HA oligosaccharides(o-HAs)and the gut microbiome remain largely unexplored.To investigate its role and metabolic fate in gut homeostasis,200 mg/day of o-HAs(average molecule weight 1 kDa)were added to an automated computer-controlled SIMulator of the Gastrointestinal tract(SIMGI).The results revealed a significant reshaping of the intestinal flora composition by o-HAs,notably reducing the Firmicutes/Bacteroides ratio.Fermentation of o-HAs by gut microbiota significantly increased the abundance of Bifidobacterium,Prevotellaceae_Prevotella,Dialister,Eubacterium,and Sutterella,but decreased that of Catenibacterium,Oscillospira,Klebsiella,and Citrobacter(P<0.05).This corresponded with significant enhancements in the content of short-chain fatty acids(SCFAs)such as acetic acid,propionic acid and n-butyric acid,highlighting the significant impact of o-HAs at the genus level.Furthermore,analysis of microbial function predicted the downregulation of pathological events in nine human diseases,particularly infectious ones(parasitic and bacterial).Potential inhibitions were observed in metabolic pathways associated with pentose and glucuronate interconversions as well as cationic antimicrobial peptide resistance.These findings underscore the in vitro prebiotic effects of o-HAs and their potential relevance in managing diverticular diseases or preventing metabolic disorders through the regulation of gut microbiota.展开更多
Objective:Critically appraise the current state of alternate temporal bone training techniques(virtual reality(VR)simulation,3D-printed models,and mental practice(MP))compared to traditional and cadaver methods.Databa...Objective:Critically appraise the current state of alternate temporal bone training techniques(virtual reality(VR)simulation,3D-printed models,and mental practice(MP))compared to traditional and cadaver methods.Databases Reviewed:PubMed,Cochrane,Web of Science.Methods:Search terms utilized“temporal bone training”,“temporal bone surgical modalities”,and“training modalities temporal bone surgery”with“3D”,“rapid prototyp*”,“stereolithography”,“additive manufact*”,“plaster”,“VR”,“virtual reality”,“animal model”,“animal temporal bone”,and“synthetic”with“AND”for all literature.Exclusion criteria:non-ENT,non-English,and did not compare against alternative/traditional methods.Results:10 studies were included with 322 participants(83.9%ENT residents and 16.1%medical students).Costs include the FDM printer($300),materials($5/3D model),and<$5,000 for freeware simulator hardware.The Welling scale was used in 50%of studies.Alternate methods produced comparable or improved assessment scores to traditional and cadaver methods.Injuries were reported in three VR studies,with two reported significantly lower injury scores in the intervention groups.Time to completion was not significantly different in four VR studies,except for one finding that the time to visualize the incus was significantly lower in the intervention group.Performance after MP was not statistically different.Conclusion:More data are needed to assess whether the alternate methods are comparable to cadaveric dissection in temporal bone training.3D models and VR simulation demonstrate promising potential for novel trainees to acquire the basic skills and produce performance comparable to or significantly better than traditional methods of lectures,textbooks,CT images,and operative videos.展开更多
With the advancement of more electric aircraft(MEA)technology,the application of electro-hydrostatic actuators(EHAs)in aircraft actuation systems has become increasingly prevalent.This paper focuses on the modeling an...With the advancement of more electric aircraft(MEA)technology,the application of electro-hydrostatic actuators(EHAs)in aircraft actuation systems has become increasingly prevalent.This paper focuses on the modeling and mode switching analysis of EHA used in the primary flight control actuation systems of large aircraft,addressing the challenges associated with mode switching.First,we analyze the functional architecture and operational characteristics of multi-mode EHA,and sumarize the operating modes and implementation methods.Based on the EHA system architecture,we then develop a theoretical mathematical model and a simulation model.Using the simulation model,we analyze the performance of the EHA during normal operation.Finally,the performance of the EHA during mode switching under various functional switching scenarios is investigated.The results indicate that the EHA meets the performance requirements in terms of accuracy,bandwidth,and load capacity.Additionally,the hydraulic cylinder operates smoothly during the EHA mode switching,and the response time for switching between different modes is less than the specified threshold.These findings validate the system performance of multi-mode EHA,which helps to improve the reliability of EHA and the safety of aircraft flight control systems.展开更多
This paper introduces the experience and practice in constructing the practical teaching system for the course“Electric Machine and Drive.”In response to the current status of cultivating innovative practical abilit...This paper introduces the experience and practice in constructing the practical teaching system for the course“Electric Machine and Drive.”In response to the current status of cultivating innovative practical abilities among electrical engineering majors,based on the independently developed virtual simulation experimental teaching platform for Electric Machine and Drive,a stepped practical teaching process consisting of“classroom teaching-experimental teaching-comprehensive training-scientific inquiry”has been elaborately designed.A hierarchical practical teaching model for the second classroom has also been established.With teaching objectives as the optimization index,the teaching content,methods and means have been optimized;the teaching process has been organized and implemented in the form of team collaboration,thus constructing a comprehensive,stepped,hierarchical,and closed-loop innovative practical teaching system.This achievement provides references and assistance for the practical teaching of the same or similar majors in other colleges and universities.展开更多
While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precip...While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precipitation behavior of Y-Ti-O oxides along grain boundaries within nanostructured ferritic alloys(NFA).This model also assessed the response of the oxides to neutron irradiation,even up sim-ulated radiation damage levels in the desired long dpa range for reactor components.Our simulations investigated how temperature and grain boundary sinks influenced the oxide characteristics of a 12YWT-like alloy during heat treatments at 1023,1123,and 1223 K.The oxide characteristics observed in our simulations were in good agreement with existing literature.Furthermore,the impact of grain bound-aries on precipitation was found to be minimal.The resulting oxide configurations and positions were used in subsequent simulations that exposed them to simulated neutron irradiation to a total accumu-lated dose of 8 dpa at three temperatures:673,773,and 873 K,and at dose rates of 10-3,10-4,and 10-5 dpa/s.This demonstrated the expected inverse relationship between oxide size and dose rate.In a long-term irradiation simulation at 873 K and 10-3 dpa/s was taken out to 66 dpa and found the oxides in the vicinity of the grain boundary were more susceptible to dissolution.Additionally,we conducted irradia-tion simulations of a 14YWT-like alloy to reproduce findings from neutron irradiation experiments.The larger oxides in the 14YWT-like alloy did not dissolve and displayed stability similar to the experimental results.展开更多
The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critica...The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critical speed points and maintain operational stability across the entire working speed range.However,the support stiffness and damping of rubber O-rings exhibit significant nonlinear frequency dependence.Conventional experimental methods for deriving equivalent stiffness and damping,based on the principle of the forced non-resonance method,require fabricating custom setups for each O-ring specification and conducting vibration tests at varying frequencies,resulting in low efficiency and high costs.This study proposes a hybrid simulation-experimental method for dynamic parameter identification.Firstly,the frequency-dependent dynamic parameters of a specific O-ring support system are experimentally obtained.Subsequently,a corresponding parametric finite element model is established to simulate and solve the equivalent elastic modulus and equivalent stiffness-damping coefficient of this O-ring support system.Ultimately,after iterative simulation,the simulated and experimental results achieve a 99.7%agreement.The parametric finite element model developed herein can directly simulate and inversely estimate frequency-dependent dynamic parameters for O-rings of different specifications but identical elastic modulus.展开更多
Model-based system-of-systems(SOS)engineering(MBSoSE)is becoming a promising solution for the design of SoS with increasing complexity.However,bridging the models from the design phase to the simulation phase poses si...Model-based system-of-systems(SOS)engineering(MBSoSE)is becoming a promising solution for the design of SoS with increasing complexity.However,bridging the models from the design phase to the simulation phase poses significant challenges and requires an integrated approach.In this study,a unified requirement modeling approach is proposed based on unified architecture framework(UAF).Theoretical models are proposed which compose formalized descriptions from both topdown and bottom-up perspectives.Based on the description,the UAF profile is proposed to represent the SoS mission and constituent systems(CS)goal.Moreover,the agent-based simulation information is also described based on the overview,design concepts,and details(ODD)protocol as the complement part of the SoS profile,which can be transformed into different simulation platforms based on the eXtensible markup language(XML)technology and model-to-text method.In this way,the design of the SoS is simulated automatically in the early design stage.Finally,the method is implemented and an example is given to illustrate the whole process.展开更多
基金Supported by the Principal Fund Project of Tarim University(TDZKSSZD201207)~~
文摘The aim of the study is to simulate actual operation of an elevator. First, it designed elevator scheduling algorithm for control ing operation of the elevator;second, it simulated elevator operation by the use of object-oriented programming language, in which double buffering technology was used to solve the problem of elevator pictures flicker at refreshing; final y, test correctness and rationality of the system.
基金support by the National Science and Technology Council under Grant No.NSTC 112-2221-E-167-017-MY3.
文摘Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments.Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energysaving potential under varying conditions.Results show that increasing the AC setpoint from 25○C to 27○C,combined with ceiling fan operation,reduced power consumption by 10%,achieving significant energy savings.Survey data confirmed that 85%of participants reported consistent thermal sensations across all conditions,with ceiling fans effectively compensating for higher setpoints through enhanced air circulation.CFDsimulations revealed that mediumspeed ceiling fan operation produced the most uniformairflowdistribution,with an average air velocity of 0.45 m/s,and minimized temperature variations,ensuring balanced thermal conditions.Temperature analysis showed a reduction in hotspots and cold zones,maintaining an average temperature deviation of less than±0.5○C.Predicted Mean Vote(PMV)evaluations at a 27○C setpoint indicated improved thermal comfort,with average PMV values around−0.3,corresponding to a“neutral”thermal sensation.These findings demonstrate the effectiveness of integrating ceiling fans with HVAC systems in achieving energy efficiency and occupant comfort,offering a sustainable approach to reducing AC energy consumption in office environments.
基金sponsored by the Science and Technology Foundation of Guizhou Provincial Education Department(No.QJJ[2024]60)Guizhou Provincial Basic Research Program(Natural Science)(No.QKHJC[2024]Youth 214)+1 种基金Science and Technology Foundation of Guizhou Minzu University(No.GZMUZK[2024]QD21)Research Projects of Anshun University(No.asxybsjj202413).
文摘To explore atomic-level phenomena in the Cu-Ni-Sn alloy,a second nearest-neighbor modified embedded-atom method(2NN MEAM)potential has been developed for the Cu-Ni-Sn system,building upon the work of other researchers.This potential demonstrates remarkable accuracy in predicting the lattice constant,with a relative error of less than 0.5%when compared to density functional theory(DFT)results,and it achieves a 10%relative error in the enthalpy of formation compared to experimental data,marking substantial advancements over prior models.The bulk modulus is predicted with a relative error of 8%compared to DFT.Notably,the potential effectively simulates the processes of melting and solidification of Cu-15Ni-8Sn,with a simulated melting point that closely aligns with the experimental value,within a 7.5%margin.This serves as a foundation for establishing a 2NN MEAM potential for a flawless Cu-Ni-Sn system and its microalloying systems.
基金funding from the National Natural Science Foundation of China(No.12462028).
文摘This study employs the Smoothed Particle Hydrodynamics(SPH)method to develop a computational fluid dynamics(CFD)model for analyzing the interaction between rogue waves and mooring systems.Four floating body configurations are investigated:(1)dual rectangular prisms,(2)rectangular prism–sphere composites,(3)sphere–rectangular prism composites,and(4)dual spheres.These configurations are systematically evaluated under varying mooring conditions to assess their hydrodynamic performance and wave attenuation capabilities.The model accurately captures the complex fluid–structure interaction dynamics between moored floating breakwaters and incident wave fields.Among the configurations,the dual rectangular prism system demonstrates superior performance in both wave dissipation and mooring force reduction.Under conditions involving dual wave makers,the influence of floating body shape and number on wave height is found to be minimal.However,dual-body arrangements consistently outperform single-body setups in terms of both energy dissipation and structural stability.From a cost-efficiency perspective,the configuration comprising two rectangular prisms connected via a single mooring system offers significant advantages in material usage and deployment feasibility.
基金supported in part by the Doctoral Initiation Fund of Nanchang Hangkong University(No.EA202403107)Jiangxi Province Early Career Youth Science and Technology Talent Training Project(No.CK202403509).
文摘This paper presents the design and ground verification for vision-based relative navigation systems of microsatellites,which offers a comprehensive hardware design solution and a robust experimental verification methodology for practical implementation of vision-based navigation technology on the microsatellite platform.Firstly,a low power consumption,light weight,and high performance vision-based relative navigation optical sensor is designed.Subsequently,a set of ground verification system is designed for the hardware-in-the-loop testing of the vision-based relative navigation systems.Finally,the designed vision-based relative navigation optical sensor and the proposed angles-only navigation algorithms are tested on the ground verification system.The results verify that the optical simulator after geometrical calibration can meet the requirements of the hardware-in-the-loop testing of vision-based relative navigation systems.Based on experimental results,the relative position accuracy of the angles-only navigation filter at terminal time is increased by 25.5%,and the relative speed accuracy is increased by 31.3% compared with those of optical simulator before geometrical calibration.
基金the Strategic Research Plan of the Centre for Marine Technology and Ocean Engineeringfinanced by the Portuguese Foundation for Science and Technology (Fundacao para a Ciência e Tecnologia-FCT) under contract UIDB/UIDP/00134/2020。
文摘A state-of-the-art review is presented of mathematical manoeuvring models for surface ships and parameter estimation methods that have been used to build mathematical manoeuvring models for surface ships. In the first part, the classical manoeuvring models, such as the Abkowitz model, MMG, Nomoto and their revised versions, are revisited and the model structure with the hydrodynamic coefficients is also presented.Then, manoeuvring tests, including both the scaled model tests and sea trials, are introduced with the fact that the test data is critically important to obtain reliable results using parameter estimation methods. In the last part, selected papers published in journals and international conferences are reviewed and the statistical analysis of the manoeuvring models, test data, system identification methods and environmental disturbances used in the paper is presented.
基金supported by the National Key R&D Program of China(No.2022YFC2803900)the National Natural Science Foundation of China(No.42276191)Zhejiang University Students Science and Technology Innovation Activity Plan(New Talent Plan)(No.2024R401185).
文摘The spatiotemporal characterization of plume sedimentation and microorganisms is critical for developing plume ecological monitoring model.To address the limitations of traditional methods in obtaining high-quality sediment,a novel sampling system with 6000 m operational capability and three-month endurance was developed.It is equipped with three sediment samplers,a set of formaldehyde preservation solution injection devices.The system is controlled by a low-power,timing-triggered controllers.To investigate low-disturbance rheological mechanisms,gap controlled rheological tests were conducted to optimize the structural design of the sampling and sealing assembly.Stress-controlled shear rheological tests were employed to investigate the mechanisms governing yield stress in sediments under varying temperature conditions and boundary roughness.Additionally,the coupled Eulerian-Lagrangian(CEL)method and sediment rheological constitutive models were employed to simulate tube-soil interaction dynamics and sediment disturbance.The radial heterogeneity of sediment disturbance and friction variation of the sampling tube were revealed.The tube was completely“plugged”at a penetration depth of 261 mm,providing critical data support to the penetration depth parameters.The deep-sea pressure test and South China Sea field trials demonstrated the system’s capability to collect and preserve quantitative time-series sediment samples with high fidelity.
基金supported by National Natural Science Foundation of China(No.11975261)。
文摘In order to support the physical research on the EAST tokamak,a new positive ion source with designed beam energy of 120 keV was proposed to be developed.Accelerator structure is one of the key components of the ion source.Through the finite element analysis method,the electrostatic analyses of insulators and grid plates were carried out,the material and structure parameters of insulators were determined.The maximum electric field around each insulator is about 4 kV/mm,and the maximum electric field between grids is about 14 kV/mm,which can meet the 120 keV withstand voltage holding.The insulation system for the positive ion source accelerator with 120 keV is designed,and the connection and basic parameters of insulators and support flanges are analyzed and determined.
文摘This paper investigates the selective maintenance o systems that perform multi-mission in succession. Selective maintenance is performed on systems with limited break time to improve the success of the next mission. In general, the duration of the mission is stochastic. However, existing studies rarely take into account system availability and the repairpersons with different skill levels. To solve this problem, a new multi-mission selective maintenance and repairpersons assignment model with stochastic duration of the mission are developed. To maximize the minimum phase-mission reliability while meeting the minimum system availability, the model is transformed into an optimization problem subject to limited maintenance resources. The optimization is then realized using an analytical method based on a self-programming function and a Monte Carlo simulation method, respectively. Finally, the validity of the model and solution method approaches are verified by numerical arithmetic examples. Comparative and sensitivity analyses are made to provide proven recommendations for decision-makers.
基金supported by the National Natural Science Foundation of China(Grant No.11805008)Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515011406)+1 种基金the Fundamental Research Funds for the Central Universities,Sun YatSen University(Grant No.23qnpy63)the Fund from Guangdong Provincial Key Laboratory(Grant No.2019B121203005).
文摘Topological invariants are crucial for characterizing topological systems.However,experimentally measuring them presents a significant challenge,especially in non-Hermitian systems where the biorthogonal eigenvectors are often necessary.We propose a general approach for measuring the topological invariants of one-dimensional non-Hermitian systems,which can be derived from the spin textures of right eigenstates.By utilizing a dilation method,we realize a non-Hermitian system without chiral symmetry on a two-qubit nuclear magnetic resonance system and measure the winding number associated with the eigenstates.In addition to examining the topology of the eigenstates,our experiment also reveals the topological structure of the energy band,which differs from that in chiral systems.Our work paves the way for further exploration of complex topological properties in non-Hermitian systems without chiral symmetry.
基金supported by the German Federal Ministry for Economic Affairs and Climate Action[BMWK SimBench-Sektor project,grant number 03EI1058C].
文摘Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot water.In order to reduce fossil energy use in the household sector,great efforts are being made to design new energy concepts that expand the use of renewable energies to supply electricity andheat.Onepossibility is toconvertparts of the natural gas grid to a hydrogen-based gas grid to deliver and store energy for urban quarters of buildings,especially with older building stock where electrification of heat via heat pumps is difficult due to technical,acoustical,and economic reasons.A comprehensive dataset was generated by a bottom-up analysis with open governmental and statistical data to determine regional building types regarding energy demand,solar potential,and existing grid infrastructure.The buildings’connections to the electricity,gas,and district heating networks are considered.From this,a representative sample dataset was chosen as input for a newly developed energy system model based on energy flow simulation.The model simulates the interaction of hydrogen generation(HG)(from excess solar energy by electrolysis),storage in a metal-hydride storage(MHS)tank,and hydrogen use in a connected fuel cell(FC),forming a local PVPtGtHP(Photovoltaic Power-to-Gas-to-Heat-and-Power)network.Next to the seasonal hydrogen storage path(HSP),a battery will complete the system to forma hybrid energy storage system(HESS).Paired with seasonal time series for PV power,electricity and heat demand,and a model for connection to grid infrastructure,the simulation of different hydrogen applications and MHS placements aims to analyze operating times and energy share of the systems’equipment and existing infrastructure.The method to obtain the data set together with the simulationmodel presented can be used by energy planners for cities,communities,and building developers to analyze the potentials of a quarter or region and plan a transition towards a more energy-efficient and sustainable energy system.
基金financially supported by the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(No.SKLGME-JBGS2403)the National Natural Science Foundation of China(No.42477205)the Hubei Provincial Innovation Group Project(No.2023AFA019).
文摘With the major developments that occurred during the past 40 years in the geotechnical engineering field,the usage of reinforcements in soils has been very common to improve the ultimate bearing capacity and reduce the footing settlements.These reinforcements consist of geogrids,geotextiles,geocells,etc.,all of which are in the geosynthetic family.Among these geosynthetic families,geocell performs better in soil-reinforced beds.In this study,we proposed the nine types of bioinspired geocells to improve the soil beds.For this purpose,a total of twenty numerical models were calculated via FLAC3D after validating the la-boratory model tests in the literature.The numerical results demonstrated that,except for the circular type,the performance of other geocell forms regarding increased bearing capacity was nearly identical.Regarding diffusion angles,only the circular and honeycomb geocells exhibited larger diffusion angles.The opening pocket diameter more significantly influenced the stress and strain of geocells.Geocells with nearly circular shapes,such as circular,honeycomb,hexagonal,and square,typically demonstrated higher confining stresses within the geocell walls.Conversely,for shapes that deviate from the circular form,such as dia-mond,re-entrant,and double V-shaped designs,the irregularity of the pocket shape could cause an uneven distribution of confining stresses,potentially leading to higher normal deformations at some specific areas and stress concentration at the wall joints.
基金supported by the National Natural Science Foundation of China(No.12175077).
文摘A thermionic gun is endowed with a long bunch tail,which presents challenges for the compact terahertz free electron laser(FEL)facility at the Huazhong University of Science and Technology.Owing to a large energy spread,the tail particles do not contribute to the radiation.In the original design,an x-direction slit is used in the dispersive section of the transport line to remove the tail particles.This paper presents an improved scheme to remove the tail by introducing an RF beam chopper system at the exit of the electron gun,to prevent a significant number of tail particles from entering the linac.The facility remains compact while effectively removing the tail of the bunch.The parameters of the beam chopper system are designed.Bunch parameters and radiation performance are analyzed via a start-to-end simulation.The findings indicate that 43%of the particles can pass through the beam chopper system for subsequent acceleration and transport,which saves the RF power,reduces beam loss in the linac,reduces background noise,and suppresses the sideband instability.Simultaneously,the beam chopper system causes an increase in beam emittance,energy spread,and an offset in the center of the bunch.These effects can be mitigated by a solenoid,linac,and steering coils.The simulation results for the FEL show that the micro-pulse energy is greater than 1.1μJ in the frequency range of 2.8-9.7 THz,and the maximum micro-pulse energy is 1.28μJ.
基金financially supported by the National Natural Science Foundation of China(32000058)the Fundamental Research Funds for the Central Universities(JUSRP622003)。
文摘The prebiotic effects of hyaluronan(HA)are widely recognized,contributing to improved gut health and immune modulation.Despite its extensive use as dietary supplement,the specific interactions between HA oligosaccharides(o-HAs)and the gut microbiome remain largely unexplored.To investigate its role and metabolic fate in gut homeostasis,200 mg/day of o-HAs(average molecule weight 1 kDa)were added to an automated computer-controlled SIMulator of the Gastrointestinal tract(SIMGI).The results revealed a significant reshaping of the intestinal flora composition by o-HAs,notably reducing the Firmicutes/Bacteroides ratio.Fermentation of o-HAs by gut microbiota significantly increased the abundance of Bifidobacterium,Prevotellaceae_Prevotella,Dialister,Eubacterium,and Sutterella,but decreased that of Catenibacterium,Oscillospira,Klebsiella,and Citrobacter(P<0.05).This corresponded with significant enhancements in the content of short-chain fatty acids(SCFAs)such as acetic acid,propionic acid and n-butyric acid,highlighting the significant impact of o-HAs at the genus level.Furthermore,analysis of microbial function predicted the downregulation of pathological events in nine human diseases,particularly infectious ones(parasitic and bacterial).Potential inhibitions were observed in metabolic pathways associated with pentose and glucuronate interconversions as well as cationic antimicrobial peptide resistance.These findings underscore the in vitro prebiotic effects of o-HAs and their potential relevance in managing diverticular diseases or preventing metabolic disorders through the regulation of gut microbiota.
文摘Objective:Critically appraise the current state of alternate temporal bone training techniques(virtual reality(VR)simulation,3D-printed models,and mental practice(MP))compared to traditional and cadaver methods.Databases Reviewed:PubMed,Cochrane,Web of Science.Methods:Search terms utilized“temporal bone training”,“temporal bone surgical modalities”,and“training modalities temporal bone surgery”with“3D”,“rapid prototyp*”,“stereolithography”,“additive manufact*”,“plaster”,“VR”,“virtual reality”,“animal model”,“animal temporal bone”,and“synthetic”with“AND”for all literature.Exclusion criteria:non-ENT,non-English,and did not compare against alternative/traditional methods.Results:10 studies were included with 322 participants(83.9%ENT residents and 16.1%medical students).Costs include the FDM printer($300),materials($5/3D model),and<$5,000 for freeware simulator hardware.The Welling scale was used in 50%of studies.Alternate methods produced comparable or improved assessment scores to traditional and cadaver methods.Injuries were reported in three VR studies,with two reported significantly lower injury scores in the intervention groups.Time to completion was not significantly different in four VR studies,except for one finding that the time to visualize the incus was significantly lower in the intervention group.Performance after MP was not statistically different.Conclusion:More data are needed to assess whether the alternate methods are comparable to cadaveric dissection in temporal bone training.3D models and VR simulation demonstrate promising potential for novel trainees to acquire the basic skills and produce performance comparable to or significantly better than traditional methods of lectures,textbooks,CT images,and operative videos.
基金supported by the Chinese Civil Aircraft Project(No.MJ-2017-S49).
文摘With the advancement of more electric aircraft(MEA)technology,the application of electro-hydrostatic actuators(EHAs)in aircraft actuation systems has become increasingly prevalent.This paper focuses on the modeling and mode switching analysis of EHA used in the primary flight control actuation systems of large aircraft,addressing the challenges associated with mode switching.First,we analyze the functional architecture and operational characteristics of multi-mode EHA,and sumarize the operating modes and implementation methods.Based on the EHA system architecture,we then develop a theoretical mathematical model and a simulation model.Using the simulation model,we analyze the performance of the EHA during normal operation.Finally,the performance of the EHA during mode switching under various functional switching scenarios is investigated.The results indicate that the EHA meets the performance requirements in terms of accuracy,bandwidth,and load capacity.Additionally,the hydraulic cylinder operates smoothly during the EHA mode switching,and the response time for switching between different modes is less than the specified threshold.These findings validate the system performance of multi-mode EHA,which helps to improve the reliability of EHA and the safety of aircraft flight control systems.
基金Project of the 14th Five-Year Plan for Educational Science in Liaoning Province(JG24DB234)Project of Graduate Education and Teaching Reform Research in Liaoning Province(LNYJG2023115)。
文摘This paper introduces the experience and practice in constructing the practical teaching system for the course“Electric Machine and Drive.”In response to the current status of cultivating innovative practical abilities among electrical engineering majors,based on the independently developed virtual simulation experimental teaching platform for Electric Machine and Drive,a stepped practical teaching process consisting of“classroom teaching-experimental teaching-comprehensive training-scientific inquiry”has been elaborately designed.A hierarchical practical teaching model for the second classroom has also been established.With teaching objectives as the optimization index,the teaching content,methods and means have been optimized;the teaching process has been organized and implemented in the form of team collaboration,thus constructing a comprehensive,stepped,hierarchical,and closed-loop innovative practical teaching system.This achievement provides references and assistance for the practical teaching of the same or similar majors in other colleges and universities.
基金supported by the Nuclear Regulatory Commission Fellowship Grant No.NRC-HQ-84-14-G-0035.
文摘While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precipitation behavior of Y-Ti-O oxides along grain boundaries within nanostructured ferritic alloys(NFA).This model also assessed the response of the oxides to neutron irradiation,even up sim-ulated radiation damage levels in the desired long dpa range for reactor components.Our simulations investigated how temperature and grain boundary sinks influenced the oxide characteristics of a 12YWT-like alloy during heat treatments at 1023,1123,and 1223 K.The oxide characteristics observed in our simulations were in good agreement with existing literature.Furthermore,the impact of grain bound-aries on precipitation was found to be minimal.The resulting oxide configurations and positions were used in subsequent simulations that exposed them to simulated neutron irradiation to a total accumu-lated dose of 8 dpa at three temperatures:673,773,and 873 K,and at dose rates of 10-3,10-4,and 10-5 dpa/s.This demonstrated the expected inverse relationship between oxide size and dose rate.In a long-term irradiation simulation at 873 K and 10-3 dpa/s was taken out to 66 dpa and found the oxides in the vicinity of the grain boundary were more susceptible to dissolution.Additionally,we conducted irradia-tion simulations of a 14YWT-like alloy to reproduce findings from neutron irradiation experiments.The larger oxides in the 14YWT-like alloy did not dissolve and displayed stability similar to the experimental results.
基金National Key R&D Program of China(No.2017YFB1304000)Fundamental Research Funds for the Central Universities,China(No.2232023G-05-1)。
文摘The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critical speed points and maintain operational stability across the entire working speed range.However,the support stiffness and damping of rubber O-rings exhibit significant nonlinear frequency dependence.Conventional experimental methods for deriving equivalent stiffness and damping,based on the principle of the forced non-resonance method,require fabricating custom setups for each O-ring specification and conducting vibration tests at varying frequencies,resulting in low efficiency and high costs.This study proposes a hybrid simulation-experimental method for dynamic parameter identification.Firstly,the frequency-dependent dynamic parameters of a specific O-ring support system are experimentally obtained.Subsequently,a corresponding parametric finite element model is established to simulate and solve the equivalent elastic modulus and equivalent stiffness-damping coefficient of this O-ring support system.Ultimately,after iterative simulation,the simulated and experimental results achieve a 99.7%agreement.The parametric finite element model developed herein can directly simulate and inversely estimate frequency-dependent dynamic parameters for O-rings of different specifications but identical elastic modulus.
基金Fifth Electronic Research Institute of the Ministry of Industry and Information Technology(HK07202200877)Pre-research Project on Civil Aerospace Technologies of CNSA(D020101)+2 种基金Zhejiang Provincial Science and Technology Plan Project(2022C01052)Frontier Scientific Research Program of Deep Space Exploration Laboratory(2022-QYKYJHHXYF-018,2022-QYKYJH-GCXD-001)Zhiyuan Laboratory(ZYL2024001)。
文摘Model-based system-of-systems(SOS)engineering(MBSoSE)is becoming a promising solution for the design of SoS with increasing complexity.However,bridging the models from the design phase to the simulation phase poses significant challenges and requires an integrated approach.In this study,a unified requirement modeling approach is proposed based on unified architecture framework(UAF).Theoretical models are proposed which compose formalized descriptions from both topdown and bottom-up perspectives.Based on the description,the UAF profile is proposed to represent the SoS mission and constituent systems(CS)goal.Moreover,the agent-based simulation information is also described based on the overview,design concepts,and details(ODD)protocol as the complement part of the SoS profile,which can be transformed into different simulation platforms based on the eXtensible markup language(XML)technology and model-to-text method.In this way,the design of the SoS is simulated automatically in the early design stage.Finally,the method is implemented and an example is given to illustrate the whole process.
