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Optimal Replacement Policy for Cold Standby System

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Chinese Journal of Mechanical Engineering 2011年第2期24卷 316-322页

作者： TAN Lin YANG Jian cheng Zhijun GUO bo College of Humanities and Social Sciences National University of Defense Technology Changsha 410073 China Guilin Airforce Academy Guilin 541003 China College of Information System andManagement National University of Defense Technology Changsha 410073 China

Investigators are attracted by the complexity and significance of preventive maintenance problem,and there are hundreds of maintenance models and methods to solve the maintenance problems of companies and army,going with a lot of investigative harvests. However,one-component system or series system is focused by most of the *** problem of preventive maintenance（PM） on cold standby repairable system does not attach importance despite the fact that the cold standby repairable system is ubiquitous in engineering *** this paper,an optimal replacement model for gamma deteriorating system is *** methodology presented uses a gamma distribution to model the material degradation,and the impact of imperfect maintenance actions on system reliability is *** an imperfect maintenance action,the state of a degrading system is assumed as a random variable and the maintenance time follows a geometric process.A maintenance policy（N）is applied by which the system will be repaired whenever it experiences the Nth PM,and an optimal policy（N~＊） could be determined numerically or analytically for minimizing the long-run average cost per unit time.A numerical example about how to confirm the optimal maintenance time by the inspecting information of liquid coupling device is given to demonstrate the use of this *** paper presents a condition-based replacement policy for cold standby repairable system under continuous *** contribution embody in two aspects,relaxing the restrictions of hypothesis and investigating the condition-based maintenance policy of the cold standby repairable system which is ignored by others.

关键词： cold standby system maintenance policy gamma process geometrical process imperfect maintenance

Modeling oxidation damage of continuous fiber reinforced ceramic matrix composites

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Acta Mechanica Sinica 2011年第3期27卷 382-388页

作者： cheng-Peng Yang Gui-Qiong Jiao bo Wang Department of Engineering Mechanics Northwestern Polytechnical University 710129 Xi'an China

For fiber reinforced ceramic matrix composites（CMCs）,oxidation of the constituents is a very important damage type for high temperature applications. During the oxidizing process,the pyrolytic carbon interphase gradually recesses from the crack site in the axial direction of the fiber into the interior of the material. Carbon fiber usually presents notch-like or local neck-shrink oxidation phenomenon,causing strength degradation. But,the reason for SiC fiber degradation is the aw growth mechanism on its surface. A micromechanical model based on the above mechanisms was established to simulate the mechanical properties of CMCs after high temperature oxidation. The statistic and shearlag theory were applied and the calculation expressions for retained tensile modulus and strength were deduced,respectively. Meanwhile,the interphase recession and fiber strength degradation were considered. And then,the model was validated by application to a C/SiC composite.

关键词： CMCs- Oxidation- Interface- Mechanical properties - Micromechanical model

Omnidirectional annealing process for scalable perovskite films

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International Journal of Minerals,Metallurgy and Materials 2022年第8期29卷 1491-1492页

作者： bo cheng Dong Wang Qianqian Chu Liang Chu State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals School of Materials Science and EngineeringLanzhou University of Tech-nologyLanzhou 730050China Institute of Carbon Neutrality and New Energy&School of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018China

Halide perovskites are promising photovoltaic materials due to the outstanding photoelectric properties and low-cost solution pro-cess;however,the low scalability and reproducibility of perovskite films hinder the *** medium annealing(LMA)method has provided a robust liquid environment and an omnidirectional heating field to modulate the growth of perovskite films for high quality with low defect density,desirable stoichiometry,high homogeneity,and less environmental *** fabricated perovskite solar cells exhibited excellent reproducibility and power conversion efficiencies exceeding 24.04%with 0.08 cm^(2) area and 23.15%with 1 cm^(2) area.

关键词： halide perovskite scalable and reproducible fabrication liquid medium annealing

Molecular understanding of cation effects on double layers and their significance to CO-CO dimerization

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National Science Review 2023年第9期10卷 125-135页

作者： Jia-bo Le Ao Chen Yongbo Kuang Jun cheng Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province Ningbo Institute of Materials Technology and EngineeringChinese Academy of Sciences State Key Laboratory of Physical Chemistry of Solid Surfaces iChEM College of Chemistry and Chemical EngineeringXiamen University Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM)

Cation effects have been shown in numerous experiments to play a significant role in electro *** understand these effects at the molecular level,we systematically investigate the structures and capacitances of electric double layers with a variety of cations as counter charges at Pt(111)-COad/water interfaces with ab initio molecular *** is encouraging to find that the computed Helmholtz capacitances for different cations are in quantitative agreement with experiments,and that the trend of cation effects on capacitances shows clear correlation with the structures of interface cations of differing sizes and hydration *** importantly,we demonstrate the Helmholtz capacitance as the key descriptor for measuring the activity of CO-CO dimerization,the rate-determining step for C2+formation in electroreduction of CO and *** work provides atomistic insights into cation effects on electric double layers and electrocatalysis that are crucial for optimizing electrode and electrolyte materials.

关键词： cation effect electrocatalysis electric double layer CO-CO dimerization ab initio molecular dynamics

Hierarchical Ti_(3)C_(2)T_(x)@ ZnO Hollow Spheres with Excellent Microwave Absorption Inspired by the Visual Phenomenon of Eyeless Urchins

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Nano-Micro Letters 2022年第5期14卷 62-76页

作者： Yan‑Qin Wang Hai‑bo Zhao Jin‑bo cheng bo‑Wen Liu Qiang Fu Yu‑Zhong Wang Collaborative Innovation Center for Eco‑Friendly and Fire‑Safety Polymeric Materials(MoE) State Key Laboratory of Polymer Materials EngineeringNational Engineering Laboratory for Eco‑Friendly Polymer Materials(Sichuan)College of ChemistrySichuan UniversityChengdu 610064People’s Republic of China College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065People’s Republic of China

Ingenious microstructure design and rational composition selection are effective approaches to realize high-performance microwave absorbers,and the advancement of biomimetic manufacturing provides a new *** nature,urchins are the animals without eyes but can“see”,because their special structure composed of regular spines and spherical photosensitive bodies“amplifies”the light-receiving ***,inspired by the above phenomenon,the biomimetic urchin-like Ti_(3)C_(2)T_(x)@ZnO hollow microspheres are rationally designed and fabricated,in which ZnO nanoarrays(length:~2.3μm,diameter:~100 nm)as the urchin spines are evenly grafted onto the surface of the Ti_(3)C_(2)T_(x) hollow spheres(diameter:~4.2μm)as the urchin spherical photosensitive *** construction of gradient impedance and hierarchical heterostructures enhance the attenuation of incident electromagnetic *** the EMW loss behavior is further revealed by limited integral simulation calculations,which fully highlights the advantages of the urchin-like *** a result,the Ti_(3)C_(2)T_(x)@ZnO hollow spheres deliver a strong reflection loss of−57.4 dB and broad effective absorption bandwidth of 6.56 GHz,superior to similar *** work provides a new biomimetic strategy for the design and manufacturing of advanced microwave absorbers.

关键词： Bioinspired Hierarchical heterostructures Ti_(3)C_(2)T_(x)MXene ZnO nanoarrays Microwave absorption

Enhanced Stem Nematode Resistance of Transgenic Sweetpotato Plants Expressing Oryzacystatin-I Gene

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Agricultural Sciences in China 2011年第4期10卷 519-525页

作者： GAO Shang YU bo zhai Hong HE Shao-zhen LIU Qing-chang Key Laboratory of Crop Genomics and Genetic Improvement Ministry of Agriculture/Beijing Key Laboratory of Crop Genetic Improvement/Laboratory of Crop Heterosis and Utilization Ministry of Education~China Agricultural University Beijing 100193 P.R.China

Enhanced stem nematode resistance of transgenic sweetpotato （cv. Lizixiang） was achieved using Oryzacystatin-I （OCI） gene with Agrobacterium tumefaciens-mediated transformation. A. tumefaciens strain EHA105 harbors a binary vector pCAMBIA1301 with OCI gene, gusA gene and hptII gene. Selection culture was conducted using 25 mg L-1 hygromycin. A total of 1 715 plants were produced from the inoculated 1 450 cell aggregates of Lizixiang via somatic embryogenesis. GUS assay and PCR analysis of the putative transgenic plants randomly sampled showed that 90.54% of them were transgenic plants. Transgenic plants exhibited significantly enhanced resistance to stem nematodes compared to the untransformed control plants by the field evaluation with stem nematodes. Stable integration of the OCI gene into the genome of resistant transgenic plants was confirmed by Southern blot analysis, and the copy number of integrated OCI gene ranged from 1 to 4. Transgene overexpression in stem nematode-resistant plants was demonstrated by quantitative real-time PCR analysis. This study provides a way for improving stem nematode resistance in sweetpotato.

关键词： Agrobacterium tumefaciens Ipomoea batatas (L.) Lam. Oryzacystatin-I gene stem nematode resistance transgenic plant

Wolfberry tree dual-model detection method and orchard target-oriented fertilization system based on photoelectric sensors

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International Journal of Agricultural and Biological Engineering 2018年第4期11卷 65-73页

作者： Shuo Yang Changyuan zhai John Long bo Zhang Hanzhe Li College of Mechanical and Electronic Engineering Northwest A&F UniversityYangling 712100China Key Laboratory of Agricultural Internet of Things Ministry of Agriculture and Rural AffairsYanglingShaanxi 712100China Department of Biosystems and Agricultural Engineering Oklahoma State UniversityStillwaterOK 74078USA

Orchard target-oriented fertilizing with on-board sensor technology can improve fertilizer efficiency and reduce environmental *** sensors are widely used for object detection because of their low cost and fast response *** paper presents a Wolfberry tree dual-model detection method and the design of an orchard target-oriented variable-rate fertilization system based on photoelectric *** dual-model detection method includes the Trunk Detection Model(TDM)and Canopy Detection Model(CDM),which can be applied for Wolfberry orchards at the green cluster and mature stages,respectively.A target-oriented fertilization system was designed using the dual-model method,and tested in the lab and Chinese Wolfberry *** laboratory test results showed that the average center offset distances on the condition of detecting trunks,continuous canopies,and discontinuous canopies were 4.1 cm,9.1 cm and 13.1 cm,*** system could ignore the signals from canes when their diameters were less than 16 mm,and also could determine the gaps within a tree when they were less than 21 *** orchard test results showed that the system accomplished target-oriented fertilization 95 times for 92 trees at the mature *** results indicated that the dual-model detection method could be used for Wolfberry trees or other trees with similar canopy changes at different growth stages.

关键词： orchard fertilizer target-oriented fertilization variable rate fertilization photoelectric sensor wolfberry orchard

Current re-vegetation patterns and restoration issues in degraded geological phosphorus-rich mountain areas:A synthetic analysis of Central Yunnan, SW China

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Plant Diversity 2017年第3期39卷 140-148页

作者： Kai Yan Sailesh Ranjitkar Deli zhai Yunju Li Jianchu Xu bo Li Yang Lu Key Laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of BotanyChinese Academy of Sciences World Agroforestry Center ICRAF East and Central Asia The State Phosphorus Resource Development and Utilization Engineering Technology Research Centre Yunnan Phosphate Chemical Group Co. Ltd College of Resource and Environment Yunnan Agricultural University

China has the largest area of inland geological phosphorus-rich(GPR) mountains in the world, where vegetation restoration is key to safeguarding the environment. We reviewed the published literature and collected new data in order to analyze re-vegetation patterns and the status of plant communities in central Yunnan. The aim of our analysis was to suggest future improvements to restoration strategies in GPR mountain regions. Our results showed that spontaneous recovery was the most widespread type of restoration. N-fixing species such as Coriaria nepalensis and Alnus nepalensis play a vital role in succession. In the past, monoculture tree plantation was the primary method used in afforestation activities in central Yunnan; in recent years however, several different methods of restoration have been introduced including the use of agroforestry systems. For practical restoration, we found that spontaneous recovery was capable of delivering the best results, but that during its early stages, restoration results were affected by several factors including erosion risk, the origin of propagates and environmental variation. In contrast, methods employing human-made communities performed better in their early stages, but were constrained by higher costs and vulnerability to degradation and erosion. The use of N-fixing species such as A. nepalensis and Acacia mearnsii in plantations were unsuccessful in restoring full ecosystem functions. The success of restoration activities in GPR mountain regions could be improved through the following measures:(1) developing a better understanding of the respective advantages and disadvantages of current natural and human-engineered restoration approaches;(2) elucidating the feedback mechanism between phosphorus-rich soil and species selected for restoration, especially N-fixing species;(3) introducing market incentives aimed at encouraging specific restoration activities such as agroforestry, and improving the industry value chain.

关键词： Systematic review Dianchi Lake Fuxian Lake Natural restoration Human engineered restoration Floristic similarity

Regional ecosystem changes under different cascade hydropower dam construction scenarios in the LRGR

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Chinese Science Bulletin 2007年第A2期52卷 106-114页

作者： zhai HongJuan CUI BaoShan HU bo WEI GuoLiang LIU ShiLiang State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Beijing Normal UniversityBeijing 100875 China

生态系统上的串联水力发出的电力水坝构造的生态的效果与在纵的范围峡区域膨胀水坝发展规模从科学家获得了许多担心。在 Lancang 河区域和纵的范围峡区域(LRGR ) 的 Yuanjiang River-Red 河区域，一个索引系统因此被建立了估计当前的生... 详细信息

生态系统上的串联水力发出的电力水坝构造的生态的效果与在纵的范围峡区域膨胀水坝发展规模从科学家获得了许多担心。在 Lancang 河区域和纵的范围峡区域(LRGR ) 的 Yuanjiang River-Red 河区域，一个索引系统因此被建立了估计当前的生态的危险并且预言可能的未来在水坝构造以后的这二个河区域的生态的危险。八种串联水力发出的电力水坝构造情形为预报在这份报纸被建立了。生态系统的突然的变化特征在计算被考虑了。象水坝构造的当前的供应，航行和旅游一样的经济好处没在计算被考虑。(1 ) 当前的生态的危险 Lancang 河区域和 Yuanjiang River-Red 河区域珍视的结果表演分别地是 0.34 和 0.43，它将在所有计划水坝的联合工作以后分别地升起到 0.900.91 和 0.860.89；(2 ) 突然的变化将在未来发生在 Lancang 河区域和 Yuanjiang River-Red 河区域身上；(3 ) 有高人的反应的间隔建设为 Lancang 河区域和 Yuanjiang River-Red 河区域，他们的多半生态的危险将分别地在以后升起到 0.560.62 和 0.420.43 被推荐。这些结果提供一个合理方法和理论参考书估计水坝建设的生态的效果，并且也把 prewarnings 给正在被计划构造串联水力发出的电力水坝的纵的范围峡区域的另外的主流。

关键词：纵向岭谷区地区生态系统变化模式瀑布