检索结果-内蒙古大学图书馆

Modeling and Performance Analysis on an Integrated System Combining Supercritical Carbon Dioxide Brayton Cycle with Leakage Feedback Utilizing a Heat Pump or Direct Compression

引用

Journal of Engineering for Gas Turbines and Power 2025年第10期147卷 101011页

作者： Qi, Yinke Ma, Xiaofeng Jiang, Peixue Zhu, Yinhai Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Beijing Key Laboratory of CO2 Utilization and Reduction Technology Department of Energy and Power Engineering Tsinghua University Beijing100084 China

CO2 leakage due to the coexistence of pressure differentials and clearances within the integrated turbine-Alternator-compressor (TAC) of the kW-level sCO2 Brayton cycle is a key issue affecting cycle efficiency and long-Term stable operation. To analyze the impact of leakage and feedback, this study examined the integrated system of the sCO2 Brayton cycle with leakage feedback and compared the system performance differences between heat pump feedback and direct compression feedback. Thermodynamic models for the Brayton cycle and feedback unit were established, and the effects of varying key parameters were analyzed. A genetic algorithm was employed to further optimize the system. The selection suggestion charts for the feedback unit were obtained. It is recommended to choose a direct compression feedback unit for conditions with a cavity pressure higher than 6.41 MPa, whereas a heat pump feedback unit is recommended for other conditions. The heat pump feedback unit has advantages particularly at high rotational speeds, low leakage factors, and low cavity pressures. The efficiency of the optimized integrated system is improved by up to 12.53%. The net power accounted for only 53.6% of the turbine output power, the main cycle compression power accounted for 32.1%, the TAC losses accounted for 10.7%, and the total compression power of the feedback unit accounted for 3.7%. Ignoring the internal leakage and losses of TAC can overestimate the power generation capacity of the Brayton cycle, resulting in it being only 79% of the ideal case after considering losses and power consumption. © 2025 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Brayton cycle

来源：评论

学校读者我要写书评

暂无评论

Study on the effects of combustion characteristics of pyrotechnic charges on pyrotechnic shocks

引用

Defence technology(防务技术) 2025年第4期46卷 79-98页

作者： Jingcheng Wang Shihui Xiong Huina Mu Xiaogang Li Yuquan Wen State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing 100081China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

This study calculates the combustion characteristics of various gas-generating and micro gas pyrotechnic charges,including aluminium/potassium perchlorate,boron/potassium nitrate,carbon black/potassium nitrate,and silicon-based delay compositions,using thermodynamic software.A multiphase flowthermal-solid coupling model was established,and the combustion process of the pyrotechnic charges within a closed bomb was *** pyrotechnic shock generated by combustion was *** combustion pressures and pyrotechnic shocks were *** simulation results demonstrated good agreement with experimental ***,the mechanism of shock generation by the combustion of pyrotechnic charges in the closed bomb was *** effects of the combustion characteristics of the pyrotechnic charges on the resulting pyrotechnic shocks were systematically ***,the shock response spectrum of the gas-generating pyrotechnic charges is greater than that of the micro gas compositions at most frequencies,particularly in the mid-field pyrotechnic shocks(3-10 kHz).Furthermore,the pyrotechnic shocks increase approximately linearly with the impulse of the gas-generating pyrotechnic charges.

关键词： Pyrotechnic charges Pyroshock Closed bomb tests Combustion characteristics Multiphase flow-thermal-solid coupling

来源：评论

学校读者我要写书评

暂无评论

Tuning thermal stability and mechanical sensitivity of polynitro compounds via integrating energetic ionic salts

Energetic Materials Frontiers

引用

Energetic Materials Frontiers 2025年第1期6卷 59-66页

作者： Xu, Mei-Qi Dong, Wen-Shuai Lu, Zu-Jia Li, Cong Zhang, Chao Zhao, Bin-Shan Li, Deng-Ke Tian, Feng-Yuan Yu, Qi-Yao Zhang, Jian-Guo State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of Technology Beijing100081 China

Polynitro energetic compounds are a class of oxidant-rich energetic materials, playing a significant role in the field of solid propellants. Generally, an increase in the number of nitro groups present in these compounds is associated with a decrease in thermal stability, while simultaneously resulting in an enhancement of mechanical sensitivity. The incorporation of nitrogen-containing organic bases in the synthesis of polynitro energetic ionic salts facilitates a more uniform distribution of charge and promotes the formation of both intramolecular and intermolecular hydrogen bonds. This strategy effectively enhances the thermal stability of HEDMs while decreasing their mechanical sensitivity. In this study, two polynitro nitrogen-containing organic salts based on the triazole framework, namely ammonium salt (4) and hydroxylamine salt (5), were designed and synthesized. Comprehensive characterization revealed that both 4 and 5 exhibited excellent detonation performance (D: 8220–8959 m⋅s−1), good thermal stability (Td: 154–175°C), and low mechanical sensitivity (IS: 30–32 J;FS: 240–288 N). Therefore, nitrogen-containing organic salts enhance the overall performance of polynitro energetic compounds, offering significant advantages in terms of safety and application potential. © 2025 The Authors

关键词： Solid propellants

来源：评论

学校读者我要写书评

暂无评论

Aerodynamic Optimization and Flow Mechanism for a Compressor Cascade at Low Reynolds Number

引用

Journal of thermal science 2025年第1期34卷 92-109页

作者： LI Lin ZHANG Jianshe CHEN Caiyan TAN Wei ZHANG Yanfeng Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing 100190China

Low-Reynolds-number effect is an important factor affecting the performance of compressors and other main components of high-altitude long-endurance unmanned aerial *** improve the flow condition and reduce flow loss under the condition of high altitude and low Reynolds number(Re),this paper proposes an optimization process based on a surrogate model,which combines the class-shape transformation method(CST),the Latin hypercube sampling(LHS)method,the light gradient-boosting machine algorithm(LightGBM),and a genetic algorithm(GA)to optimize a high-subsonic compressor *** surrogate model is verified to be accurate and can be used in the optimization *** accuracy of the GA is higher than the other algorithms under common test *** optimization results are verified by numerical simulation,and the flow differences before and after optimization are compared,especially the flow within the boundary *** changing the blade shape,the optimization process adjusts the loading distribution to delay the transition of the optimized blade on the suction surface,which changes the turbulent reattachment in the laminar separation bubble(LSB)into laminar ***,the mixing loss induced by the turbulent reattachment of the LSB and the wake loss of turbulent separation at the trailing edge are significantly reduced,and the performance of the compressor profile is finally *** addition,turbulent separation of the optimized profile is delayed reducing the range of the wake region on the suction *** this optimization process,the reduction of total pressure loss coefficient at Re of 2.5×10^(5),3.5×10^(5),and 4.5×10^(5) are 16.32%,20.76%,and 22.16%,respectively.

关键词： low Reynolds numbers compressor optimization boundary layer transition

来源：评论

学校读者我要写书评

暂无评论

Effect of Ti Additions on Mechanical and Thermodynamic Properties of W-Ti Alloys: A First-principles Study

引用

Journal of Wuhan University of technology(Materials science) 2025年第1期40卷 246-257页

作者： ZHANG Jian NIE Wei HUANG Jin ZHU Ke LIU Ruxia ZHANG Ruizhi LUO Guoqiang SHEN Qiang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Institute for Carbon Neutrality University of Science and Technology BeijingBeijing 100083China

The mechanical and thermodynamic properties of W-Ti alloys(including W_(15)Ti_(1),W_(14)Ti_(2),W_(12)Ti_(4) and W_(8)Ti_(8) alloys)were investigated by the first-principles approach based on density functional *** results indicate that W-Ti alloys except W_(8)Ti_(8) are thermodynamically *** modulus and hardness of W-Ti alloys are smaller than those of pure tungsten and gradually decrease with increasing Ti ***,their B/G ratios and Poisson's ratios exceed those of pure tungsten,suggesting that the introduction of Ti decreases the mechanical strength while enhancing the ductility of W-Ti *** thermal expansion coefficients for W-Ti alloys all surpass those of pure tungsten,indicating that the introduction of titanium exacerbates the thermal expansion behavior of W-Ti ***,elevated pressure has the capacity to suppress the thermal expansion tendencies in titanium-doped tungsten *** study offers theoretical insights for the design of nuclear materials by exploring the mechanical and thermodynamic properties of W-Ti alloys.

关键词： first-principles mechanical properties thermodynamic properties tungsten-titanium alloys

来源：评论

学校读者我要写书评

暂无评论

Study on sulfur resistance of MnO2/Beta zeolite in toluene catalytic combustion: The effect of increased acidity on catalytic performance

引用

Chinese Journal of Chemical Engineering 2025年第2期78卷 187-195页

作者： Zhuo Wang Zetao Jin Hanqi Ning Baishun Jiang Kaiyuan Xie Shufeng Zuo Qiuyan Wang Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process College of Chemistry and Chemical Engineering Shaoxing University College of Materials Science and Engineering Beijing University of Technology State Key Laboratory of Elemento-Organic Chemistry Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) College of Chemistry Nankai University

Sulfur dioxide(SO2) frequently coexist with volatile organic compounds(VOCs) in exhaust gas. The competitive adsorption of SO2and VOCs can adversely affect the efficiency of catalytic combustion,leading to catalyst poisoning and irreversible loss of activity. To investigate the impact of sulfur poisoning on the catalysts, we prepared the Mn O2/Beta zeolite, and a corresponding series of sulfur-poisoned catalysts through in-situ thermal decomposition of(NH4)2SO4. The decrease in toluene catalytic activity of poisoned Mn O2/Beta zeolite primarily results from the conversion of the active species Mn O2to Mn SO4. However, the crystal structure and the porous structure of Mn O2/Beta zeolite were stable, and original structure was still maintained when 1.6%(mass) sulfur species were introduced. Furthermore,the extra-framework Al of Beta zeolite could capture sulfur species to generate Al2(SO4)3, thereby reducing sulfur species from reacting with Mn4+active sites. The combination of sulfur and Beta zeolite was found to directly produce new strong-acid sites, thus effectively compensating for the effect of reduced Mn4+active species on the catalytic activity.

关键词： (NH4)2SO4 Beta zeolite In-situ thermal decomposition Sulfur-resistant mechanism VOCs catalytic oxidation

来源：评论

学校读者我要写书评

暂无评论

Development of a versatile and high-loading capacity yeast surface assembly system via SpyC/SpyT conjugation

引用

Process Biochemistry 2025年 155卷 13-22页

作者： Xu, Ke Liu, Hailin Du, Chao Zhang, Faying Wang, Wenya Zhang, Guimin State Key Laboratory of Green Biomanufacturing College of Life Science and Technology Beijing University of Chemical Technology Beijing100029 China State Key Laboratory of Biocatalysis and Enzyme Engineering School of Life Sciences Hubei University Wuhan430062 China

The yeast surface display (YSD) system for enzyme immobilization has a wide range of applications and is of great value in various studies. However, despite the many advantages of the YSD system, the amount of proteins it can display is limited, which restricts its potential applications. To enhance the applicability of the YSD system, we introduced a highly efficient and stable conjugation tool (SpyCatcher-SpyTag (SpyC-SpyT)) into the YSD system and developed a Saccharomyces cerevisiae surface assembly (SSA) system with high loading capacity. The SpyC-SpyT can spontaneously form molecular isopeptide bonds, and the target proteins can be assembled in the SSA system within 5 min. By increasing the copy of SpyC and integrating the expression fragment into the rDNA region, we successfully screened a genetically stable and high-copy strain that could assemble ∼7.8 × 106 SpyT-eGFP molecular count/cell. The organophosphate hydrolase immobilized by the SSA system not only has the similar enzyme activity as the free enzyme, but also has improved thermal stability and enhanced tolerance to acidic and alkaline environments. Further, we found that the immobilized enzyme still retained 77.7 % of its enzyme activity after 6 cycles. In conclusion, we successfully constructed a novel, efficient and stable SSA system for the development of the YSD system. © 2025 Elsevier Ltd

关键词： Enzyme immobilization

来源：评论

学校读者我要写书评

暂无评论

Enhancing the photocatalytic efficiency by the molecular modification effect derived from pollutant adsorption on highly crystalline BiOBr

引用

Journal of Environmental sciences 2025年第2期148卷 263-273页

作者： Yang Jin Tongyin Liu Yanpeng Mao Fan Li Chun Hu National Engineering Laboratory for Reducing Emissions from Coal Combustion Engineering Research Center of Environmental Thermal Technology of Ministry of EducationShandong Key Laboratory of Energy Carbon Reduction and Resource UtilizationSchool of Energy and Power EngineeringShandong UniversityJinan 250061China Beijing Enterprises Water Group<China>Investment Limited Beijing 100102China Institute of Environmental Research at Greater Bay Key Laboratory for Water Quality and Conservation of the Pearl River DeltaMinistry of EducationGuangzhou UniversityGuangzhou 510006China Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

The adsorption of pollutants can not only promote the direct surface reaction,but also modify the catalyst itself to improve its photoelectric characteristics,which is rarely studied for water treatment with inorganic photocatalyst.A highly crystalline BiOBr(c-BiOBr)was synthesized by a two-step preparation *** to the calcination,the highly crystalline enhanced the interface interaction between pollutant and *** complex of organic pollutant and[Bi_(2)O_(2)]^(2+)could promote the active electron transfer from the adsorbed pollutant to c-BiOBr for the direct pollutant degradation by holes(h^(+)).Moreover,the pollutant adsorption actually modified c-BiOBr and promoted more unpaired electrons,which would coupling with the photoexcitation to promote generate more O_(2)^(•-).The molecular modification effect derived from pollutant adsorption significantly improved the removal of *** work strongly deepens the understanding of the molecularmodification effect from the pollutant adsorption and develops a novel and efficient approach for water treatment.

关键词： Highly crystalline BiOBr Pollutant adsorption Molecular modification Photocatalysis Water treatment

来源：评论

学校读者我要写书评

暂无评论

Topological Design of Low Dielectric Ladder-like Polysilsesquioxane and Copolymers

引用

Chinese Journal of Polymer science 2025年第3期43卷 477-487页

作者： Wen-Jie Fan Meng Xie Jin-Feng Tian Yan He Shuang Xia Wen-Xin Fu Key Laboratory of Science and Technology on High-Tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Polymer Materials Engineering Polymer Research Institute of Sichuan UniversityChengdu 610065China

Low dielectric constant(low-k)materials are critical for advanced packaging in high-density microelectronic devices and high-frequency communication *** polysiloxanes,which are characterized by their unique double-chain structure and intrinsic microporosity,offer remarkable advantages in terms of thermal stability,oxidation resistance,and dielectric ***,structural defects in ladder polysiloxanes,such as cage-like and irregular oligomers,and their effects on dielectric properties remain *** this study,a series of ladder-like polysiloxanes(X-TMS)with diverse side groups weresynthesized via a one-step base-catalyzed *** influence of the benzocyclobutene(BCB)side groups on the formation of regular ladder structures was systematically ***,BCB incorporation disrupted the structural regularity,favoring the formation of cage-like and irregular topologies,which were extensively characterized using 29silicon nuclear magnetic resonance spectroscopy(^(29)Si-NMR),Fourier transform infrared spectroscopy(FTIR),gel permeation chromatography(GPC),and X-ray diffraction(XRD).These structural defects were beneficial for improving the hydrophobicity and thermal *** of X-TMS with commercial DVS-BCB resins further enhanced the mechanical properties,with the elastic modulus increasing from 3.6 GPa to 4.4 GPa and water absorption reduced from 0.33 wt%to 0.06 wt%.This study establishes a clear correlation between topological structures and material *** findings not only advance the understanding of the structure-property relationships in ladder polysiloxanes but also provide a novel approach for designing high-performance interlayer dielectric materials for next-generation microelectronics.

关键词： Ladder polymer Topological structures Polysiloxanes Low dielectric Benzocyclobutene

来源：评论

学校读者我要写书评

暂无评论

Barocaloric effect in ferroelastic Pb_(3)(VO_(4))_(2)

引用

Chinese Physics B 2025年第3期34卷 506-510页

作者： Pengtao Cheng Zuhua Chen Chengliang Zhang Zhengming Zhang Bing Li Dunhui Wang Hangzhou Dianzi University Hangzhou 310018China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China Center for Crystal Research and Development Key Laboratory of Functional Crystals and Laser TechnologyKey Laboratory of CryogenicsTechnical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

The barocaloric effect is considered as one of the most promising refrigeration with the potential to replace traditional gas compression *** of the main obstacles to the application of barocaloric materials lies in the requirement for high driving *** this paper,we report on the barocaloric effect of Pb_(3)(VO_(4))_(2),which exhibits a ferroelastic transition from a high-temperature trigonal structure to a low-temperature monoclinic structure at 357 K,accompanied by a substantial volume *** entropy change induced by hydrostatic pressure can reach up 14 J·kg^(-1)·K^(-1)under a relatively low pressure of 80 *** work is expected to expand the selection range of barocaloric materials.

关键词： solid-state refrigeration barocaloric effect ferroelastic transition

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：