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Clustering compression-based computation-efficient calibration method for digital twin modeling of HVAC system

Building Simulation 2023年第6期16卷 997-1012页

作者： Jie Lu Xiangning Tian chenxin Feng Chaobo Zhang Yang Zhao Yiwen Zhang Zihao wang Institute of Refrigeration and Cryogenics Zhejiang UniversityHangzhouChina Architectural Design&Research Institute of Zhejiang University Co. Ltd.HangzhouChina Center for Balance Architecture Zhejiang UniversityHangzhouChina Jiaxing Research Institute Zhejiang UniversityHangzhouChina

Digital twin is regarded as the next-generation technology for the effective operation of heating,ventilation and air conditioning(HVAC)*** is essential to calibrate the digital twin models to match them closely with real physical *** real-time calibration methods cannot satisfy such requirements since the computation loads are beyond acceptable *** address this challenge,this study proposes a clustering compression-based method to enhance the computation efficiency of digital twin model calibration for HVAC *** method utilizes clustering algorithms to remove redundant data for achieving data ***,a hierarchical multi-stage heuristic model calibration strategy is developed to accelerate the calibration of similar component *** basic idea is that once a component model is calibrated by heuristic methods,its optimal solution is utilized to narrow the ranges of parameter probability distributions of similar *** doing so,the calibration process can be guided,so that fewer iterations would be *** performance of the proposed method is evaluated using the operational data from an HVAC system in an industrial *** show that the proposed clustering compression-based method can reduce computation loads by 97%,compared to the conventional calibration *** the proposed hierarchical heuristic model calibration strategy is capable of accelerating the calibration process after clustering and saves 14.6%of the time costs.

关键词： heating,ventilation and air conditioning systems model calibration digital twin heuristic methods clustering compression hierarchical calibration

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In-pit coal mine personnel uniqueness detection technology based on personnel positioning and face recognition

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International Journal of Mining Science and Technology 2013年第3期23卷 357-361页

作者： Sun Jiping Li chenxin Research Institute of Information Engineering China University of Mining & Technology

Since the coal mine in-pit personnel positioning system neither can effectively achieve the function to detect the uniqueness of in-pit coal-mine personnel nor can identify and eliminate violations in attendance management such as multiple cards for one person, and swiping one's cards by others in China at present. Therefore, the research introduces a uniqueness detection system and method for in-pit coal-mine personnel integrated into the in-pit coal mine personnel positioning system, establishing a system mode based on face recognition + recognition of personnel positioning card + release by automatic detection. Aiming at the facts that the in-pit personnel are wearing helmets and faces are prone to be stained during the face recognition, the study proposes the ideas that pre-process face images using the 2D-wavelet-transformation-based Mallat algorithm and extracts three face features: miner light, eyes and mouths, using the generalized symmetry transformation-based algorithm. This research carried out test with 40 clean face images with no helmets and 40 lightly-stained face images, and then compared with results with the one using the face feature extraction method based on grey-scale transformation and edge detection. The results show that the method described in the paper can detect accurately face features in the above-mentioned two cases, and the accuracy to detect face features is 97.5% in the case of wearing helmets and lightly-stained faces.

关键词： Coal mine Uniqueness detection Recognition of personnel positioning cards Face recognition Generalized symmetry transformation

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Experimental Investigation of Flame Structure and Combustion Limit During Premixed Methane/Air Jet Flame and Sidewall Interaction

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Energy Engineering 2021年第1期118卷 37-52页

作者： Ying Chen Jianfeng Pan Qingbo Lu Yu wang chenxin Zhang School of Energy and Power Engineering Jiangsu UniversityZhenjiang212013China

The effects of inlet gas parameters and sloping sidewall angle on the flame structure and combustion limit with and without sidewall were experimentally *** height and impact angle were obtained by chemiluminescence intensity analysis of CH****,the combustion characteristics of flame with and without sidewall at different equivalence ratios were explored;then,the influence of Reynolds number and inlet gas temperature on flame structure and combustion limit of v-shaped flame with sidewall were analyzed,and the results with sidewall were compared with those without ***,the variation trend of flame parameters with different sloping sidewall angles was *** experimental results show that the existence of sidewall makes flame shape change from“M-shaped”to“inverted N-shaped”,and conical shape to trapezoidal *** inhibition effect of sidewall on flame stretching downstream is strengthened with the increase in Reynolds number;but as the temperature of the inlet gas increases,the inhibitory effect is obviously *** sloping sidewall angle decreases from 90°to 55°at 5°intervals,flame height and impact angle of v-shaped flame reach the extreme value whenβ=80°.Compared with the case without sidewall,the range of v-shaped flame with sidewall has no obvious trend of broadening or shrinking when inlet gas temperature is increased;however,as sloping sidewall angle decreases,the range of the v-shaped flame shrinks obviously and flammability limit increases significantly.

关键词： Sidewall premixed flame flame-wall interaction flame structure combustion limit

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Potential application of electron work function in analyzing fracture toughness of materials

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Journal of Materials Science & Technology 2017年第10期33卷 1128-1133页

作者： Hao Lu chenxin Ouyang Xianguo Yan Jian wang Guomin Hua Reinaldo Chung D.Y.Li Department of Chemical and Materials Engineering University of Alberta Edmonton. Alberta T6G 1H9 Canada College of Materials Science and Engineering Donghua University Shanghai 201620 China School of Mechanical Engineering Taiyuan University of Science and Technology Taiyuan 030024 China Extraction Reliability Engineering Suncor Energy Inc. Fort McMurray Alberta Canada

Fracture toughness determines materials＇ resistance to fracture, which is measured often using impact or bending tests. However, it is difficult to evaluate fracture toughness of coatings and small *** this article, using white irons as sample materials, we explore a possible approach of using electron work function（EWF） as an indicator in evaluating fracture toughness of hard metallic materials. This parameter is promising for being utilized to analyze toughness of protective coatings and small objects as well as bulk materials. Through comparison with results obtained from impact tests and elastic modulus measurement, effectiveness of this EWF approach is demonstrated.

关键词： Fracture toughness Elastic modulus Electron work function

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绣球菌风味果冻的研制

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农产品加工 2019年第16期 10-12,16页

作者：王晨昕张玉仙李宗浩万敏冯翠萍山西农业大学食品科学与工程学院

以绣球菌为原料,研制一种新型的绣球菌风味果冻。以复合凝胶、柠檬酸、木糖醇为因素,采用单因素试验和响应面设计,以感官评价、弹性和咀嚼性为指标,筛选制作果冻的最佳配方。结果表明,最佳配方为固形物含量0.8g/100mL的绣球菌液,添加量... 详细信息

以绣球菌为原料,研制一种新型的绣球菌风味果冻。以复合凝胶、柠檬酸、木糖醇为因素,采用单因素试验和响应面设计,以感官评价、弹性和咀嚼性为指标,筛选制作果冻的最佳配方。结果表明,最佳配方为固形物含量0.8g/100mL的绣球菌液,添加量分别为复合凝胶1.06%,木糖醇12.02%,柠檬酸0.10%。在此条件下研制出的新型风味果冻感官评分为94分,弹性1.5mm,咀嚼性2.53mJ。

关键词：绣球菌果冻感官评价质构

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Direct electron transfer of glucose oxidase on the carbon nanotube electrode

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Science China Chemistry 2004年第2期47卷 113-119页

作者： CAI chenxin CHEN Jing LU Tianhong Department of Chemistry Nanjing Normal University Nanjing 210097 China Department of Chemistry Nanjing Normal University Nanjing 210097 China Department of Chemistry Nanjing Normal University Nanjing 210097 China

The direct electron transfer of glucose oxidase (GOx) immobilized onto the surface of the carbon nanotube (CNT)-modified glassy carbon (CNT/GC) electrode is reported. The direct electron transfer rate of GOx is greatly enhanced when it was immobilized onto the surface of CNT/GC electrode. Cyclic voltammetric results show a pair of well-defined and nearly symmetric redox peaks, which corresponds to the direct electron transfer of GOx, with the formal potential (E 0′), which is almost independent on the scan rates, of about ?0.456 V (vs. SCE) in the phosphate buffer solution (pH 6.9). The apparent heterogeneous electron transfer rate constant (ks) of GOx at the CNT/GC electrode surface is estimated to be (1.74 ± 0.42) s-1, which is much higher than that reported previously. The dependence of E 0′ on solution pH indicates that the direct electron transfer of GOx is a two-electron-transfer coupled with two-proton-transfer reaction process. The experimental results also demonstrate that the immobilized GOx retains its bioelectrocatalytic activity toward the oxidation of glucose. The method presented here can be easily extended to obtain the direct electrochemistry of other enzymes or proteins.

关键词： carbon nanotube, chemically modified electrode, direct electrochemistry, bioelectrocatalysis, glucose oxidase, glucose.

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Molecular dynamics simulation of the test of single-walled carbon nanotubes under tensile loading

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Science China(Technological Sciences) 2007年第1期50卷 7-17页

作者： FU chenxin CHEN YunFei JIAO JiWei School of Mechanical Engineering MEMS Key Laboratory of China Educational MinistrySoutheast UniversityNanjing 210096China State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China

Molecular dynamics (MD) simulations were performed to do the test of sin-gle-walled carbon nanotubes (SWCNT) under tensile loading with the use of Bren-ner potential to describe the interactions of atoms in SWCNTs. The Young’s modulus and tensile strength for SWCNTs were calculated and the values found are 4.2 TPa and 1.40―1.77 TPa, respectively. During the simulation, it was found that if the SWCNTs are unloaded prior to the maximum stress, the stress-strain curve for unloading process overlaps with the loading one, showing that the SWCNT’s de-formation up to its fracture point is completely elastic. The MD simulation also demonstrates the fracture process for several types of SWCNT and the breaking mechanisms for SWCNTs were analyzed based on the energy and structure be-havior.

关键词： carbon nanotube molecular dynamics Young’s modulus carbene

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Dielectric and thermal properties characterisation and evaluation of novel epoxy materials for high-voltage power module packaging

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High Voltage 2024年第5期9卷 1021-1032页

作者： Zhengdong wang Ganqiu Yang Xiaolong Cao Mengli Li Tong Zhang chenxin Liu Yuanhang Zhou Yonghong Cheng School of Mechanical and Electrical Engineering Xi'an University of Architecture and TechnologyXi'anChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

Internal insulation of high-voltage power modules is facing interesting failure risks,including high temperature overheating,breakdown fault,material cracking etc.,so it is imperative to urgently develop new dielectric materials with high thermal conductivity(λ),outstanding electrical insulation,and thermal stability properties.A method to construct controllable liquid crystalline cross-linking networks based on the synthesis of biphenyl epoxy monomer and the change of curing agent structures and curing temperature is *** uniform nematic rod-like liquid crystalline domains were obtained by using 4,4-diaminodiphenylmethane as a curing agent under a pre-curing temperature of 105°*** resulting film(abbreviated as TD-105)exhibitedλup to 0.53 W m^(-1) K^(-1) and a dielectric breakdown strength of 57.69 kV mm^(-1),which showed a simultaneous enhancement of 178%and 16%,respectively,compared to traditional bisphenol A epoxy ***,it also exhibited lower dielectric loss and magnitude of partial discharge while having higher glass-transition temperature(190°C).A novel idea for the development of high-performance epoxy insulating materials for the application of high-voltage and large-power electrical equipment is provided.

关键词： thermal dielectric curing

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Exploring the interconnectivity of biomimetic hierarchical porous Mg scaffolds for bone tissue engineering:Effects of pore size distribution on mechanical properties,degradation behavior and cell migration ability

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Journal of Magnesium and Alloys 2021年第6期9卷 1954-1966页

作者： Gaozhi Jia Hua Huang Jialin Niu chenxin Chen Jian Weng Fei Yu Deli wang Bin Kang Tianbing wang Guangyin Yuan Hui Zeng Department of Bone&Joint Surgery Peking University Shenzhen HospitalShenzhen Peking University-The Hong Kong University of Science and Technology Medical CenterShenzhen 518036China National Engineering Research Center of Light Alloy Net Forming&State Key Laboratory of Metal Matrix Composite Shanghai Jiao Tong UniversityShanghai 200240China Beijing Key Laboratory of Civil Aircraft Structures and Composite Materials Beijing Aircraft Technology Research Institute of COMACBeijing 102211China National&Local Joint Engineering Research Center of Orthopaedic Biomaterials Peking University Shenzhen HospitalShenzhen 518036China Department of Orthopaedics Peking University People's HospitalBeijing 100044China

Interconnectivity is the key characteristic of bone tissue engineering scaffold modulating cell migration,blood vessels invasion and transport of nutrient and ***,efforts and understanding of the interconnectivity of porous Mg is limited due to the diverse architectures of pore struts and pore size distribution of Mg scaffold *** this work,biomimetic hierarchical porous Mg scaffolds with tailored interconnectivity as well as pore size distribution were prepared by template replication of infiltration *** scaffold with better interconnectivity showed lower mechanical *** interconnected pores would enhance the interconnectivity of the whole scaffold and reduce the change of ion concentration,pH value and osmolality of the degradation microenvironment due to the lower specific surface ***,the degradation rates of five tested Mg scaffolds were no different because of the same geometry of strut *** cell culture and evaluation of cell density at both sides of four typical Mg scaffolds indicated that cell migration through hierarchical porous Mg scaffolds could be enhanced by not only bigger interconnected pore size but also larger main pore *** summary,design of interconnectivity in terms of pore size distribution could regulate mechanical strength,microenvironment in cell culture condition and cell migration potential,and beyond that it shows great potential for personalized therapy which could facilitate the regeneration process.

关键词： Bone tissue engineering Porous Mg scaffold Interconnectivity Pore size distribution Cell migration

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7A04-T6铝合金圆管的材性试验和本构模型研究

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钢结构（中英文） 2019年第12期34卷 35-39页

作者：李进军丁永君王衬心李振宇荣彬万纹宇天津大学建筑设计研究院天津300073 天津大学天津300072

为研究7A04铝合金材料的力学性能和本构模型,完成了15个取自圆管管材的材性试样的静力拉伸试验,对比分析了试验所得的应力-应变曲线与Ramberg-Osgood模型、Baehre模型、Mazzolani模型。分析结果表明:Ramberg-Osgood模型与试验所得的应力... 详细信息

为研究7A04铝合金材料的力学性能和本构模型,完成了15个取自圆管管材的材性试样的静力拉伸试验,对比分析了试验所得的应力-应变曲线与Ramberg-Osgood模型、Baehre模型、Mazzolani模型。分析结果表明:Ramberg-Osgood模型与试验所得的应力-应变曲线吻合最好,尤其是在拐点附近;所求得Ramberg-Osgood模型中的应变硬化指数n值略小于SteinHardt的建议取值。

关键词： 7A04-T6铝合金应力-应变曲线本构模型应变硬化指数

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