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Numerical Study of Water Transport and Operating Strategy for Fuel Cells with Segmented Water Management Flow Fields

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Journal of Thermal Science 2024年第4期33卷 1577-1589页

作者： CHEN Chengdai WANG Changhong zheng Zijun School of Materials and Energy Guangdong University of TechnologyGuangzhou510006China

The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is proposed in this study,i.e.a half separated-half coupled cathode(HSHC)flow field which has two inlets but just one outlet.A 3D numerical PEMFC model is applied to study the effect of the HSHC flow field on PEMFC performance and its operating strategy in terms of operating *** study results are shown as follows:Compared with the two conventional cathode flow fields,the HSHC flow field improves the water balance along the channel and increases the current density by 17.1%at a cathode stoichiometry of *** is because the HSHC flow field can overcome the water loss at channels upstream and the water accumulation at channels *** draw water phenomenon(DWP)in the HSHC flow field is observed,which is mainly affected by the water vapor pressure of *** on the DWP,cooling channel inlet flow rates can be used to adjust water balance,but severe water loss should be *** addition,the inlet temperature control in HSHC flow field should be that cell temperature>cathode channel inlet temperature>cooling channel inlet temperature>ambient temperatures for better water balance.

关键词： proton exchange membrane fuel cells channel design segmented water management water balance operating strategy

Accurately tracking hypersonic gliding vehicles via an LEO mega-constellation in relay tracking mode

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Journal of Systems Engineering and Electronics 2024年第1期35卷 211-221页

作者： LI Zhao WANG Yidi zheng Wei College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

In order to effectively defend against the threats of the hypersonic gliding vehicles(HGVs),HGVs should be tracked as early as possible,which is beyond the capability of the ground-based *** benefited by the developing megaconstellations in low-Earth orbit,this paper proposes a relay tracking mode to track HGVs to overcome the above *** whole tracking mission is composed of several tracking intervals with the same *** each tracking interval,several appropriate satellites are dispatched to track the *** that are planned to take part in the tracking mission are selected by a new derived observability *** tracking performances of the proposed tracking mode and the other two traditional tracking modes,including the stare and track-rate modes,are compared by *** results show that the relay tracking mode can track the whole trajectory of a HGV,while the stare mode can only provide a very short tracking ***,the relay tracking mode achieve higher tracking accuracy with fewer attitude controls than the track-rate mode.

关键词： target tracking mega-constellation hypersonic gliding vehicle(HGV) sensor selection observability analysis

A Fibonacci View on the Galois NFSR Used in Trivium

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Journal of Systems Science & Complexity 2024年第3期37卷 1326-1350页

作者： WANG Hongyu zheng Qunxiong QI Wenfeng PLA Strategic Support Force Information Engineering University Zhengzhou 450001China

Trivium is an international standard of lightweight stream ciphers(ISO/IEC 29192-3:2012).In this paper,the Trivium-like NFSRs,a class of Galois NFSRs generalized from the Galois NFSR of Trivium,are studied from the perspective of Fibonacci *** is shown that an n-stage Trivium-like NFSR cannot be equivalent to an n-stage Fibonacci NFSR,which is proved by showing the existence of“collision initial states”.As an intermediate conclusion,a necessary and sufficient condition for a kind of linear degeneracy of a Trivium-like NFSR is obtained from the persepective of interleaved ***,the smallest stage number of a Fibonacci NFSR that can generate all the output sequences of an n-stage Trivium-like NFSR is shown to be greater than n-7 and this value is no less than 371=287+min{93,84,111}specifically for the 288-stage Galois NFSR used in *** results contradict the existence of a equivalent Fibonacci model of Trivium NFSR of small stage,which implies that Trivium algorithm possesses a fair degree of immunity against“structure attack”.

关键词： Fibonacci NFSR galois NFSR interleaved sequence linear degeneracy trivium

Optimal impulsive rendezvous for highly elliptical orbits using linear primer vector theory

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Chinese Journal of Aeronautics 2024年第3期37卷 194-207页

作者： Maozhang zheng Jianjun LUO Zhaohui DANG National Key Laboratory of Aerospace Flight Dynamics Northwestern Polytechnical UniversityXi’an 710072China

In this paper,minimum-fuel rendezvous is investigated for the case in which the reference orbit is highly *** this end,the well-known Tschauner-Hempel equations are used to describe the relative motions between rendezvous spacecraft and the ***’s primer vector theory is then applied on this linear but time-varying *** analytical solution of the required primer vector for this problem is then derived by using a recently developed *** the existing non-optimal solutions which don’t satisfy the conditions,the methods are further designed to improve the performance by shifting impulses or adding a new ***,two algorithms are developed for free-impulse time-fixed rendezvous *** first algorithm can determine the globally optimal trajectory with the optimal number of *** second one enables for fast trajectory *** proposed algorithms have been successfully applied to coplanar and three-dimensional rendezvous problems in which the target is flying on highly elliptical orbits.

关键词： Orbital transfer Optimal trajectory Primer vector Tschauner-Hempel equations Globally planning Fast planning

A Graded Speed Control Method for Cyborg Rats Based on Electrical Stimulation of the Cuneiform Nucleus

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Journal of Bionic Engineering 2024年第3期21卷 1334-1346页

作者： Hanyi Ling Le Han Nenggan zheng Qiushi Academy for Advanced Studies(QAAS) Zhejiang UniversityHangzhou310007China The State Key Lab of Brain-Machine Intelligence Zhejiang UniversityHangzhou310007China College of Biomedical Engineering&Instrument Science Zhejiang UniversityHangzhou310007China College of Computer Science and Technology Zhejiang UniversityHangzhou310007China CCAI by MOE and Zhejiang Provincial Government(ZJU) Hangzhou310007China

The precise movement speed regulation is a key factor to improve the control effect and efficiency of the cyborg ***,the current stimulation techniques cannot realize the graded control of the *** this study,we achieved the multi-level speed regulation of cyborg rats in the large open field and treadmill by specifically targeting the Cuneiform Nucleus(CnF)of the Mesencephalic Locomotor Region(MLR).Detailed,we measured the influence of each stimulation parameter on the speed control process which included the real-time speed,accelerated speed,response time,and acceleration *** concluded that the pulse period and the pulse width were the main determinants influencing the accelerated speed of cyborg *** the amplitude of stimulation was found to affect the response time exhibited by the cyborg *** study provides valuable insights into the regulation of rat locomotion speed and highlights the potential for utilizing this approach in various experimental settings.

关键词： Cyborg rats Cuneiform nucleus Graded control Speed regulation

Microscale spherical TiO_(2)powder prepared by hydrolysis of TiCl_(4)solution:Synthesis and kinetics

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Particuology 2024年第1期84卷 60-71页

作者： Peiyi Yan Ying Zhang Shili zheng School of Rare Earths University of Science and Technology of ChinaHefei230026China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341119China Key Laboratory of Green Process and Engineering National Engineering Research Center of Green Recycling for Strategic Metal ResourcesInstitute of Process EngineeringChinese Academy of SciencesBeijing100190China State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization Panzhihua617000China

Hydrolysis of TiCl_(4)solution is capable of preparing microscale TiO_(2)*** research studied the synthesis of microscale spherical TiO_(2)powders and the hydrolysis *** effects of the flow field generated by different agitators and baffles in the crystallizer,the initial free acid concentration,the initial equivalent TiO_(2)concentration,and the temperature on the hydrolysis progress and powder morphology were systematically *** results show that the flow field in a crystallizer can significantly affect the morphology and particle size of the powders,and the axial flow can improve the sphericity of the *** increased free HCl and equivalent TiO_(2)concentrations in the pregnant solution inhibit the forward hydrolysis reaction,prolong the time to reach equilibrium,and reduce the *** appropriate temperature matching the compositions of the pregnant solution is crucial for the powder morphology and *** with sizes ranging from around 5 um-40μm can be tuned under controlled flow field,solution compositions,and temperature *** addition,the Cheng and Wunderlich modified Avrami equation was used for the crystallization kinetic *** effects of the free HCl concentration,equivalent TiO_(2)concentration,and hydrolysis temperature are reflected in the reaction rate constant and active nuclei reduction *** the free HCl and equivalent TiO_(2)concentrations will reduce the reaction rate constant and accelerate the deactivation of the active nuclei,thus increasing the final powder size,while increasing the temperature will lead to the opposite results.

关键词： TiCl_(4) Hydrolysis Microscale TiO_(2) Spherical Kinetics

Numerical investigation on dynamic response of the screen mesh in vibrating screening through DEM-FEM co-simulation

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Particuology 2024年第4期87卷 205-217页

作者： Huan Zhang Xiao zheng Weimin Jing Key Laboratory of MetallurgicalEquipment and Control Technology Ministry of EducationWuhan University of Science and TechnologyWuhan430081 China Hubei Key Laboratory of Mechanical Transmssion and Manufacturing Engineering Wuhan University of Science and TechnologyWuhan430081China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing400044China

Dynamic response of the screen mesh is of great significance in the optimum vibrating screen *** this paper,based on the DEM-FEM co-simulation method,the effect of screening parameters on the dynamic response of the screen mesh is explored and the mechanism is revealed on the particle ***,a virtual experiment on a linear vibrating screen was carried out to analyze the screening pa-rameters'effect with both impact load and sustained stress inflicted on the screen ***,the time-domain evolution regularity of the screen mesh LVA(Local Vibration Amplitude)under different particle plugging conditions was investigated based on the ***,the influence of screening parameters on LVA and its distribution was *** results show that the screening parameters can greatly affect the screen mesh LVA and its distribution by changing the movement of the granular material and the particle penetration probability,which provides an important basis for the optimal design of the screen mesh and its supporting structure.

关键词： Vibrating screen Dynamic response DEM-FEM Screening parameters Local vibration amplitude

Recent progress in functional modification and crosslinking of bioprosthetic heart valves

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Regenerative Biomaterials 2024年第1期3卷 1-16页

作者： Cheng zheng Li Yang Yunbing Wang National Engineering Research Center for Biomaterials Sichuan UniversityChengdu 610064China

Valvular heart disease(VHD),clinically manifested as stenosis and regurgitation of native heart valve,is one of the most prevalent cardiovascular diseases with high *** valve replacement surgery has been recognized as golden standard for the treatment of *** to the clinical application of transcatheter heart valve replacement technic and the excellent hemodynamic performance of bioprosthetic heart valves(BHVs),implantation of BHVs has been increasing over recent years and gradually became the preferred choice for the treatment of ***,BHVs might fail within 10-15 years due to structural valvular degeneration(SVD),which was greatly associated with drawbacks of glutaraldehyde crosslinked BHVs,including cytotoxicity,calcification,component degradation,mechanical failure,thrombosis and immune *** prolong the service life of BHVs,much effort has been devoted to overcoming the drawbacks of BHVs and reducing the risk of *** this review,we summarized and analyzed the research and progress on:(i)modification strategies based on glutaraldehyde crosslinked BHVs and(ii)nonglutaraldehyde crosslinking strategies for BHVs.

关键词： bioprosthetic heart valves modification crosslinking anticalcification antithrombosis

Physiological and psychological responses to tended plant communities with varying color characteristics

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Journal of Forestry Research 2024年第1期35卷 183-201页

作者： Siyuan zheng Yanzhen Zhou Haiyan Qu School of Architecture and Urban Planning Shenyang Jianzhu UniversityShenyang 110168People’s Republic of China

Exposure to plants has been reported to promote health and reduce stress,and plant color has direct impacts on physical and mental *** used images of common types of tended plant communities in Shenyang,China,with combinations of yellow,green,and red foliage,as experimental stimuli.A total of 27 images were used as visual *** used electroencephalography to measureαwave activity(8-13 Hz)in 40 subjects while they viewed visual *** data were combined with subjective questionnaire data to analyze the relaxing effect of images of tended plant communities with different color types and proportions on *** results revealed that,although there were slight differences between the electroencephalography and psychological findings,women were significantly more relaxed than men after viewing the *** and psychological responses varied with the types and proportions of colors in the tended plant communities:those of foliage with combinations of two or three colors induced stronger responses than images with a single ***,(1)for one-color plant communities,green or yellow plant communities induced a stronger relaxation effect than red plant communities;(2)for two-color plant communities,the optimal color proportion was 55%+45%,and the green+yellow and green+red color combinations induced a stronger relaxation effect;(3)for three-color plant communities,the relaxation effect was strongest when the color proportion was 55%green+25%yellow+20%*** data would provide a plant color matching in future plant landscape design,which may be helpful for creating healthy and relaxing environments.

关键词： Plant community Color type Color ratio Electroencephalography Subjective questionnaire