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Condition-based Maintenance Optimization for Gamma Deteriorating Systems under Performance-based Contracting

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Chinese Journal of Mechanical Engineering 2023年第1期36卷 34-50页

作者： Xi Zhu Liang Wen Juan Li Mingchang Song Qiwei Hu Army Engineering University of PLA ShijiazhuangChina

With the further development of service-oriented,performance-based contracting(PBC)has been widely adopted in industry and manufacturing.However,maintenance optimization problems under PBC have not received enough attention.To further extend the scope of PBC’s application in the field of maintenance optimization,we investigate the condition-based maintenance(CBM)optimization for gamma deteriorating systems under PBC.Considering the repairable single-component system subject to the gamma degradation process,this paper proposes a CBM optimization model to maximize the profit and improve system performance at a relatively low cost under PBC.In the proposed CBM model,the first inspection interval has been considered in order to reduce the inspection frequency and the cost rate.Then,a particle swarm algorithm(PSO)and related solution procedure are presented to solve the multiple decision variables in our proposed model.In the end,a numerical example is provided so as to demonstrate the superiority of the presented model.By comparing the proposed policy with the conventional ones,the superiority of our proposed policy is proved,which can bring more profits to providers and improve performance.Sensitivity analysis is conducted in order to research the effect of corrective maintenance cost and time required for corrective maintenance on optimization policy.A comparative study is given to illustrate the necessity of distinguishing the first inspection interval or not.

关键词： Performance-based contracting Condition-based maintenance Gamma process Profit maximization Inspection interval

Out-of-Plane Compressive Behavior for UHMWPE/Polyurethane Composites after Hygrothermal Treatment

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Journal of Beijing Institute of Technology 2019年第1期28卷 176-183页

作者： Libao zhu Yongqing Li Xi Zhu Zixu zhu Department of Naval Architecture Engineering Naval University of Engineering

Quasi-static and high strain rate compressive behaviors and failure mechanisms of hygrothermal treated ultra-high molecular weight polyethylene/polyurethane(UHMWPE/PU)composites have been studied in this paper.Firstly,the UHMWPE composites were immersed in water at 70℃.The out-ofplane compression test was then performed on the dry/wet state specimens at quasi-static states(0.001-0.01 s^(-1))and high strain rate states(800-2 400 s^(-1)).The split Hopkinson pressure bar(SHPB)was adopted in the dynamic tests and waveform shapers were used to smooth and control the incident pulse.The results show that there are two platforms for the water absorption curve of UHMWPE composites.The absorption of moisture reduces the quasi-static compressive strength of the material while initially increasing,then decreasing the dynamic compressive strength.Matrix plasticization,fiber/matrix interface degradation and void expansion are the main factors affecting the irregular change of static/dynamic compressive strength of UHMWPE composites.

关键词： ultra-high molecular weight polyethylene(UHMWPE)composite hygrothermal aging split Hopkinson pressure bar(SHPB) compression

Chemical Scissors Tailored Nano‑Tellurium with High‑Entropy Morphology for Efficient Foam‑Hydrogel‑Based Solar Photothermal Evaporators

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Nano-Micro Letters 2024年第3期16卷 149-168页

作者： Chenyang xing Zihao Li Ziao Wang Shaohui Zhang Zhongjian xie Xi Zhu Zhengchun Peng State Key Laboratory of Radio FrequencyHeterogeneous Integration Shenzhen UniversityShenzhen 518060People’s Republic of China Center for Stretchable Electronics and NanoSensors College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060People’s Republic of China School of Science and Engineering The Chinese University of Hong KongShenzhenShenzhen 518172People’s Republic of China Institute of Pediatrics Shenzhen Children’s HospitalShenzhen 518038GuangdongPeople’s Republic of China International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060People’s Republic of China

The development of tellurium(Te)-based semiconductor nanomaterials for efficient light-to-heat conversion may offer an effective means of harvesting sunlight to address global energy concerns.However,the nanosized Te(nano-Te)materials reported to date suffer from a series of drawbacks,including limited light absorption and a lack of surface structures.Herein,we report the preparation of nano-Te by electrochemical exfoliation using an electrolyzable room-temperature ionic liquid.Anions,cations,and their corresponding electrolytic products acting as chemical scissors can precisely intercalate and functionalize bulk Te.The resulting nano-Te has high morphological entropy,rich surface functional groups,and broad light absorption.We also constructed foam hydrogels based on poly(vinyl alcohol)/nano-Te,which achieved an evaporation rate and energy efficiency of 4.11 kg m^(−2)h^(−1)and 128%,respectively,under 1 sun irradiation.Furthermore,the evaporation rate was maintained in the range 2.5-3.0 kg m^(−2)h^(−1)outdoors under 0.5-1.0 sun,providing highly efficient evaporation under low light conditions.

关键词： Tellurium High entropy Electrochemical modification Solar absorption Evaporation rate

Study on discharge characteristics and improving surface hydrophobicity of epoxy resin by nanosecond pulse excited argon/hexamethyldisiloxane jet array

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High Voltage 2022年第4期7卷 771-781页

作者： Zhiyan Liu Jingang Xu Xi Zhu Feng Liu Zhi Fang College of Electrical Engineering and Control Science Nanjing Tech UniversityNanjingChina

Surface flashover of insulating materials induced by pollution and moisture environment is one of the main reasons for the damage of power system and electrical equipment.The improvement of the insulating materials surface hydrophobicity is key important,which can prevent the pollutants and water attachment,and enhance the insulating perfor-mance.In this paper,the super-hydrophobic film is formed on the surface of epoxy resin by a one-dimensional(1D)argon(Ar)jet array driven by nanosecond pulse power supply with hexamethyldisiloxane(HMDSO)addition.The influences of the processing time and HMDSO content on the epoxy resin surface hydrophobicity are investigated.It shows that with 0.04%HMDSO,the jet array achieves a best hydrophobic treatment effect on the epoxy resin surface.After 60 s treatment,the apparent contact angle(ACA)of the epoxy resin surface increases from 60.3°of the untreated surface to 150.0°.The wettability of epoxy resin surface does not change too much as the treatment time beyond 60 s.The maximum ACA value 153.4°appears at 120 s processing time,which is just slightly higher than that of 60 s treatment time.The epoxy resin surface morphology and chemical feature before and after plasma processing are characteristics by the scanning electron microscopy(SEM),atomic force microscopy(AFM),Fourier transform infra-red spectroscopy and X-ray photoelectron spectroscopy.It shows that the treated epoxy resin surface is covered with dense coral like particles in nanoscales,the original C=O、C-H and other organic functional groups are replaced by Si-(CH3),Si-O-Si and other silicon containing groups,and the Si content increases from 0.4%to 28.0%.The experimental results provide important references to develop jet array as an efficient tool to enhance the surface hydrophobicity and insulating performance of insulating materials.

关键词： resin surface characteristics

Human skin bacterial microbiota homeostasis:A delicate balance between health and disease

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微生物(英文) 2023年第2期2卷 107-120页

作者： Yibin zhu xi Yu Gong Cheng Tsinghua University‐Peking University Joint Center for Life Sciences School of MedicineTsinghua UniversityBeijingChina Shenzhen Bay Laboratory Institute of Infectious DiseasesShenzhenChina

As the largest organ of the body,the skin acts as a barrier to prevent diseases and harbors a variety of beneficial bacteria.Furthermore,the skin bacterial microbiota plays a vital role in health and disease.Disruption of the barrier or an imbalance between symbionts and pathogens can lead to skin disorders or even systemic diseases.In this review,we first provide an overview of research on skin bacterial microbiota and human health,including the composition of skin bacteria in a healthy state,as well as skin bacterial microbiota educating the immune system and preventing the invasion of pathogens.We then discuss the diseases that result from skin microbial dysbiosis,including atopic dermatitis,common acne,chronic wounds,psoriasis,viral transmission,cutaneous lupus,cutaneous lymphoma,and hidradenitis suppurativa.Finally,we highlight the progress that utilizes skin microorganisms for disease therapeutics,such as bacteriotherapy and skin microbiome transplantation.A deeper knowledge of the interaction between human health and disease and the homeostasis of the skin bacterial microbiota will lead to new insights and strategies for exploiting skin bacteria as a novel therapeutic target.

关键词： homeostasis human diseases skin bacterial microbiota therapeutics

Evaluation of the Effect of Multiparticle on Lithium-Ion Battery Performance Using an Electrochemical Model

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IEEE/CAA Journal of Automatica Sinica 2022年第10期9卷 1896-1898页

作者： Yizhao Gao Jingzhe zhu xi Zhang IEEE the School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Dear editor,This letter focuses on modeling the electrode heterogeneity by extending the pseudo-two-dimensional model(P2D)with actual particle-size distributions(PSD).The effects of different particle characterization... 详细信息

关键词： particle Battery editor

Groove formation on Phobos from reimpacting orbital ejecta of the Stickney crater

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Earth and Planetary Physics 2022年第3期6卷 294-303页

作者： xiangYu xi Min Ding MengHua zhu State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacaoChina China National Space Administration Macao Center for Space Exploration and ScienceMacaoChina

Numerous linear grooves have long been recognized as covering the surface of Phobos, but the mechanisms of their formation are still unclear. One possible mechanism is related to the largest crater on Phobos, the Stickney crater, whose impact ejecta may slide,roll, bounce, and engrave groove-like features on Phobos. When the launch velocity is higher than the escape velocity, the impact ejecta can escape Phobos. A portion of these high-velocity ejecta are dragged by the gravitational force of Mars, fall back, and reimpact Phobos.In this research, we numerically test the hypothesis that the orbital ejecta of the Stickney crater that reimpact Phobos could be responsible for a particular subset of the observed grooves on Phobos. We adopt impact hydrocode i SALE-2 D(impact-Simplified Arbitrary Lagrangian Eulerian, two-dimensional) to simulate the formation of the Stickney crater and track its impact ejecta, with a focus on orbital ejecta with launch velocities greater than the escape velocity of Phobos. The launch velocity distribution of the ejecta particles is then used to calculate their trajectories in space and determine their fates. For orbital ejecta reimpacting Phobos, we then apply the sliding boulder model to calculate the ejecta paths, which are compared with the observed groove distribution and length to search for causal relationships. Our ejecta trajectory calculations suggest that only ~1% of the orbital ejecta from the Stickney crater can reimpact Phobos. Applying the sliding boulder model, we predict ejecta sliding paths of 9-20 km in a westward direction to the east of the zone of avoidance, closely matching the observed grooves in that region. The best-fit model assumes an ejecta radius of ~150 m and a speed restitution coefficient of 0.3, consistent with the expected ejecta and regolith properties. Our calculations thus suggest the groove class located to the east of the zone of avoidance may have been caused by reimpact orbital ejecta from the Stickney crater.

关键词： Phobos groove formation Stickney crater reimpact ejecta

Measuring air traffic complexity based on small samples

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Chinese Journal of Aeronautics 2017年第4期30卷 1493-1505页

作者： Xi Zhu xianbin CAO Kaiquan CAI School of Electronics and Information Engineering Beihang University Beijing 100191 China Beijing Key Laboratory for Network-Based Cooperative Air Traffic Management Beijing 100083 China

Air traffic complexity is an objective metric for evaluating the operational condition of the airspace. It has several applications, such as airspace design and traffic flow management.Therefore, identifying a reliable method to accurately measure traffic complexity is important. Considering that many factors correlate with traffic complexity in complicated nonlinear ways,researchers have proposed several complexity evaluation methods based on machine learning models which were trained with large samples. However, the high cost of sample collection usually results in limited training set. In this paper, an ensemble learning model is proposed for measuring air traffic complexity within a sector based on small samples. To exploit the classification information within each factor, multiple diverse factor subsets（FSSs） are generated under guidance from factor noise and independence analysis. Then, a base complexity evaluator is built corresponding to each FSS. The final complexity evaluation result is obtained by integrating all results from the base evaluators. Experimental studies using real-world air traffic operation data demonstrate the advantages of our model for small-sample-based traffic complexity evaluation over other stateof-the-art methods.

关键词： Air traffic control Air traffic complexity Correlation analysis Ensemble learning Feature selection

Flavivirus-infected hosts attract more mosquitoes to bite

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Frontiers of Medicine 2023年第2期17卷 355-357页

作者： Hong Zhang xi Yu Yibin zhu Gong Cheng Tsinghua University-Peking University Joint Center for Life Sciences School of MedicineTsinghua UniversityBeijing 100084China Institute of Infectious Diseases Shenzhen Bay LaboratoryShenzhen 518000China

Mosquitoes adapt to different habitats and feed on a variety of animals.Anthropophilic female mosquitoes,such as Aedes aegypti and Anopheles gambiae,have a strong innate drive to detect their human hosts and acquire blood meals for their egg production[1].Their biting behavior is not only annoying but also transmits many life-threatening diseases.Aedes aegypti has evolved to specialize in biting humans and is the vector of many mosquito-borne diseases,such as dengue virus(DENV),Zika virus(ZIKV),yellow fever virus(YFV),and chikungunya virus(CHIKV)[2].Anopheles gambiae,the malaria vector,has also developed a preference for humans,which makes it an effective vector for disease transmission.Many mosquito-borne infectious diseases pose an increasing global health threat,and consequently,there is an urgent need to control their transmission.

关键词： diseases infected yellow