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Surface morphologies of Mg-Gd alloy particle during its reactions with O_(2) and Teflon

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Defence technology（防务技术） 2024年第3期33卷 209-221页

作者： Yifan Li Hongtao Yang Aifeng Jiang Dongming Song Yanchun Li Department of Chemical engineering Nanjing University of Science and TechnologyNanjing 210097China Xi'an Modern Chemistry research institute Xi'an 710065China Southwest technology and engineering research institute Chongqing 400039China

Mg-Gd alloy particle has exhibited its unique combustion properties as the fuel of Mg/Teflon/Viton(MTV).Mg-Gd alloy/Teflon/Viton(MGTV)could burn at lower ambient pressure than *** further investigate the reaction of MGTV in air,it was investigated via thermo gravity-differential scanning calorimetry(TG-DSC).Meanwhile,the morphologies and element distributions on the alloy surface during the reaction of MGTV in air were investigated via scanning electronic microscope-mapping-electronic differential ***,a similar experimental protocol on the Mg-Gd alloy particle during oxidation was also *** results showed that owning to a protective oxide shell,the onset oxidation temperature of Mg-Gd alloy is higher than ***,the onset oxidation temperature of the exceeded Mg-Gd alloy in MGTV is significantly lower than that of the exceeded Mg in *** was due to the existence of GdOF,which could significantly lower the oxidation temperature of the exceeded ***,a possible reaction mechanism was *** fascinating oxidation properties of Mg-Gd alloy suggested its promising applications in energetic materials.

关键词： Mg-Gd alloy Energetic materials Morphology EDS GdOF

A novel matrix topology-based analysis method of thermal circuits for reliability optimization of HSER

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Chinese Journal of Aeronautics 2024年第4期37卷 479-492页

作者： Huimin LIANG Bo LI Jiaxin YOU Shan JIANG Mengtong ZHU Aobo WANG Department of Electrical engineering Harbin Institute of TechnologyHarbin 150001China Nanjing research institute of Electronics technology Nanjing 210008China

Hermetically Sealed Electromagnetic Relay(HSER), used in aviation and aerospace,demands high reliability due to its critical applications. Given its complex operating conditions, efficient thermal analysis is essential for optimizing reliability. The commonly used Finite Element Method(FEM) is often time-consuming and may not be efficient or adaptable for complex multi-dimensional system calculations and design processes. This paper introduces an analysis method for thermal networks based on matrix perspective technology, encompassing matrix transformation, backpropagation of the heat path model, temperature rise calculation, solution comparison, and product implementation. Using the similarity theory of heat circuits, a basic thermal unit is established. Based on the fundamental connection between key components, a thermal network for a typical HSER is designed. An experimental system is set up, and the thermal network model's accuracy is confirmed using test data. Employing the topology analysis method, the topology of the thermal network is analyzed under both coil-energized and de-energized states. Potential thermal paths are identified, leading to optimized solutions for the HSER. Utilizing these solutions, the thermal path matrix topology model is backpropagated to the thermal path for temperature rise calculations. When compared to prototype HSER test data, the efficiency and accuracy of this matrix topology-based analysis method are confirmed.

关键词： Thermal networks HSER(Hermetically Sealed Electromagnetic Relay) Heat-circuit topology model Heat-circuit matrix Optimization design

A model reduction approach for discrete-time linear time-variant systems with delayed inputs

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Science China(Information Sciences) 2024年第4期67卷 197-217页

作者： Ai-Guo WU Guang-Ren DUAN Yu WANG Jie ZHANG School of Mechanical engineering and Automation Harbin Institute of Technology(Shenzhen) HIT Wuhu Robot technology research institute Center for Control Science and technology Southern University of Science and Technology

A model reduction approach is presented for discrete-time linear time-variant input-delayed systems. According to this proposed approach, a dynamical variable is constructed by taking advantage of the current state and historical information of input. It is revealed that the behavior of this dynamical variable is governed by a discrete-time linear delay-free system. It is worth noting that the presented variable transformation does not require the system matrix to be invertible. Based on the reduced delay-free models,stabilizing control laws can be easily obtained for the original delayed system. For the case with a single input delay, the constructed variable is an exact prediction for the future state, and thus the stabilizing control law could be designed by replacing the future state with its prediction. Finally, three discrete-time periodic systems with delayed input are employed to illustrate how to utilize the presented model reduction approaches.

关键词： reduction approach predictor-based feedback time-varying systems delayed input periodic system

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Ru-doped functional porous materials for electrocatalytic water splitting

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Nano research 2024年第3期17卷 982-1002页

作者： Chongao Tian Rui Liu Yu Zhang Wenxiu Yang Bo Wang Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials Advanced Technology Research Institute(Jinan)Advanced Research Institute of Multidisciplinary ScienceSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing institute of technology Library Beijing Institute of TechnologyBeijing 100081China

Electrolytic water splitting(EWS)is an attractive and promising technique for the production of hydrogen ***,the sluggish kinetic rate of hydrogen/oxygen evolution reactions leads to a high overpotential and low energy *** to date,Pt/Ir-based nanocatalysts have become the state-of-the-art EWS catalysts,but disadvantages such as high cost and low earth abundance greatly limit their applications in EWS *** an attractive candidate for the Pt/Ir catalysts,series of Ru-based nanomaterials have aroused much attention for their low price,Pt-like hydrogen bond strength,and high EWS *** particular,Ru-doped functional porous materials have been becoming one of the most representative EWS catalysts,which can not only achieve the dispersion and adjustment for active Ru sites,but also simultaneously solve the problems of mass transfer and catalytic conversion in *** this review,the design and preparation strategies of Ru-doped functional porous materials toward EWS in recent years are summarized,including Ru-doped metal organic frameworks(MOFs),Ru-doped porous organic polymers(POPs),and their ***,detailed structure–activity relationships induced by the tuned geometric/electronic structures of Ru-doped functional porous materials are further depicted in this *** but not least,the challenges and perspectives of Ru-doped functional porous materials catalysts are reasonably proposed to provide fresh ideas for the design of Ru-based EWS catalysts.

关键词： Ru-based catalyst functional porous materials electrolytic water splitting oxygen evolution reaction hydrogen evolution reaction

The behaviors of gas-liquid two-phase flow under gas kick during horizontal drilling with oil-based muds

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Petroleum 2024年第1期10卷 49-67页

作者： Yu Su Huiyun Ma Jianhua Guo Xinyu Shen Zhaoliang Yang Jie Wu engineering technology research institute PetroChina Southwest Oil & Gas Field Company

Natural gas is easily soluble in oil-based muds(OBM), leading to complex flow behavior in wellbores,especially in horizontal wells. In this study, a new transient flow model considering wellbore-formation coupling and gas solubility on flow behavior is developed to simulate gas kicks during horizontal drilling with OBM. Furthermore, the effect of gas solubility on parameters such as bottom-hole pressure(BHP),gas void fraction and mixture velocity in the flow behavior is analyzed. Finally, several critical factors affecting flow behavior are investigated and compared to gas kicks in water-based muds(WBM) where the effect of solubility is neglected. The results show that the invading gas exists as dissolved gas in the OBM and as free gas in the WBM. Before the gas escapes from the OBM, the pit gain is zero and there is barely any change in the BHP, annulus return flow rate and mixture velocity, which means that detecting gas kicks through these warning signs can be challenging until they get very close to the surface and develop rapidly. However, in WBM drilling, these parameters change quickly with the increasing gas kick time. Additionally, for both cases, the longer the horizontal length and the greater reservoir permeability,the greater the decrease in BHP, and the shorter the time for gas to migrate from the bottom-hole to the wellhead. A larger flow rate contributes to a greater initial BHP and a lesser BHP reduction. This research is of value in characterizing gas kick behavior and identifying novel ways for early gas kick detection during horizontal drilling with OBM.

关键词： Flow behavior Gas solubility Gas kick Horizontal drilling Oil-based muds Water-based muds

Constructal design of printed circuit recuperator for S-CO_(2)cycle via multi-objective optimization algorithm

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Science China(Technological Sciences) 2024年第1期67卷 285-294页

作者： DAN ZhiSong FENG HuiJun CHEN LinGen LIAO NaiBing GE YanLin institute of Thermal Science and Power engineering Wuhan Institute of TechnologyWuhan 430205China College of Power engineering Naval University of EngineeringWuhan 430033China Hubei Provincial engineering technology research Center of Green Chemical Equipment Wuhan 430205China School of Mechanical&Electrical engineering Wuhan Institute of TechnologyWuhan 430205China AECC Hunan Aviation Powerplant research institute Zhuzhou 412002China

Based on a constructal theory,the structure design of a printed circuit recuperator with a semicircular heat transfer channel for supercritical CO_(2)cycle is carried ***,a complex function composed of weighted sum of the reciprocal of total heat transfer rate and total pumping power consumption is regarded as an optimization objective,and total volumes of the recuperator and heat transfer channel are regarded as *** optimal heat transfer channel radius and minimum complex function of the recuperator are *** turns out that heat transfer rate,pumping power consumption,and complex function under the optimal construct of recuperator are reduced by 15.10%,82.44%,and 32.33%,*** exists the optimal single plate channel number which results in the double minimum complex ***,for the purpose of minimizing the reciprocal of heat transfer rate and pumping power consumption,NSGA-II algorithm is used to achieve multi-objective optimization,and the minimum deviation index derived by the decision-making methods is 0.076,which can be taken as multi-objective optimal design scheme for printed circuit recuperator with semicircular heat transfer *** findings presented here can serve as theoretical recommendations for the structure design of printed circuit recuperator.

关键词： constructal theory supercritical CO_(2)cycle printed circuit heat exchanger heat transfer rate pumping power consumption multi-objective optimization

Perspective on powder technology for all-solid-state batteries:How to pair sulfide electrolyte with high-voltage cathode

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Particuology 2024年第3期86卷 55-66页

作者： Jiangkui Hu Shijie Yang Yingying Pei Xilong Wang Yulong Liao Shuai Li Aolong Yue Jia-Qi Huang Hong Yuan School of Materials Science&engineering Beijing Institute of TechnologyBeijing100081China Advanced research institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China

Sulfide solid electrolytes(SEs)have attracted ever-increasing attention due to their superior roomtemperature ionic conductivity(~10^(-2) S cm^(-1)).Additionally,the integration of sulfide SEs and highvoltage cathodes is promising to achieve higher energy ***,the incompatible interfaces between sulfide SEs and high-voltage cathodes have been one of the key factors limiting their ***,this review presents a critical summarization of the interfacial issues in all-solid-state lithium batteries based on sulfide SEs and high-voltage cathodes and proposes strategies to stabilize the electrolyte/cathode ***,the future research direction of electrolyte/cathode interfaces and application prospects of powder technology in sulfide-based ASSLBs were also discussed.

关键词： Sulfide solid electrolytes High-voltage cathodes Electrode/electrolyte interfaces All-solid-state lithium batteries

Observation and verification of surface electrical explosion driven by radial-distributed pulsed current in laboratory lightning strike test

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High Voltage 2024年第1期9卷 137-149页

作者： Ruoyu Han Yuchen Cao Yakun Liu Xi Chen Ting Li Chen Li Pengfei Li State Key Laboratory of Explosion Science and technology Beijing Institute of TechnologyBeijingChina School of Mechatronical engineering Beijing Institute of TechnologyBeijingChina Department of Electrical engineering Shanghai Jiaotong UniversityShanghaiChina Beijing institute of Astronautical System engineering BeijingChina Aerospace research institute of Materials and Processing technology BeijingChina

The laboratory lightning test is essential for assessing the effectiveness of lightning strike protection(LSP).Particularly,direct lightning strike damage can be performed with pulsed current injection into the *** paper focuses on the dynamic process of arc plasma and shock wave behaviour in the vicinity of the‘strike’point.A rod-plate discharge load is built for testing aluminium and coated plate under 40-kA-level pulsed *** visualisation of the luminous discharge plasma and its flow field via high-speed photography(from different angles)is meticulously designed and implemented,synchronised with electro-physical *** results indicate some new mechanisms for lightning strike damage,apart from the impulse heat loading from the thermal *** transient current injection through the arc root concentrates on a thin skin layer(skin-depth effect),with the radial-attenuated current density,driving asynchronously electrical explosions on the plate *** inhomogeneous Joule heating of the plate leads to outwardly propagating phase transition and shock wave along the conductive *** addition,the electro-thermal instability is observed and regarded as the seed of irregular erosion *** information reveals two different plasma states of main discharge arc channel and adjacent surface electrical *** correspondence of the physical mechanism of electrical explosion and optical radiation is *** images for different regions depict erosion characteristics and summarise influencing factors,further confirming the mechanism *** research clarifies the role of skin-depth effect in transaction arc erosion for electrode,complements the electrical explosion theory with unevenly distributed current and helps optimise strategies of LSP.

关键词： electrical lightning radial

Constructal design of a rectangular porous fin considering minimization of maximum temperature difference and pumping power consumption

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Science China(Technological Sciences) 2024年第3期67卷 919-929页

作者： LIU XiaoYe FENG HuiJun CHEN LinGen GE YanLin institute of Thermal Science and Power engineering Wuhan Institute of TechnologyWuhan 430205China College of Power engineering Naval University of EngineeringWuhan 430033China Hubei Provincial engineering technology research Center of Green Chemical Equipment Wuhan 430205China School of Mechanical&Electrical engineering Wuhan Institute of TechnologyWuhan 430205China

A heat dissipation model of a rectangular porous fin is established based on constructal theory. First, the constructal design of rectangular porous fin is conducted by selecting a complex function minimization, which composed of linear weighting sum of maximum temperature difference and pumping power consumption, as optimization objective. Effects of gap height, air inlet velocity, total porous fin volume and porosity on the optimal constructs are investigated, respectively. The findings show that the complex function can attain its double minimum at a value of 0.802 when the fin length and number are optimized, and the corresponding optimal fin length and number are 8.01 mm and 10, respectively. In comparison to original design, the complex function and maximum temperature difference after twice optimization are decreased by 19.80% and 66.31%, ***, the comprehensive performance of porous fin is improved by simultaneously optimizing the fin length and number. The artificial neural network is applied to predict the fin performances, which is used to conduct multi-objective optimization based on NSGA-II algorithm. Optimal structure of porous fin for multiple requirements is gained by LINMAP and TOPSIS decisionmaking strategies. The findings in this study can serve as theoretical guides for fin thermal designs of electronic devices.

关键词： constructal theory rectangular porous fin pumping power consumption maximum temperature difference complex function multi-objective optimization