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An Approximation Bound Analysis for Lasserre’s Relaxation in Multivariate Polynomial Optimization

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Journal of the Operations Research Society of China 2013年第3期1卷 313-332页

作者： jiawang Nie Department of Mathematics University of California San Diego9500 Gilman DriveLa JollaCA 92093USA

Suppose f,g1,…,gm are multivariate polynomials in x∈R^(n)and their degrees are at most *** the problem:Minimize f(x)subject to g1(x)≥0,…,gm(x)≥*** f_(min)(resp.,f_(max))be the minimum(resp.,maximum)of f on the feasible set S,and f_(sos)be the lower bound of_(fmin)given by Lasserre’s relaxation of order *** paper studies its approximation *** a suitable condition on g1,…,gm,we prove that(f_(max)−f_(sos))≤Q(f_(max)−f_(min))with Q a constant depending only on g1,…,gm but not on *** particular,if S is the unit ball,Q=O(n^(d));if S is the hypercube,Q=O(n^(2d));if S is the boolean set,Q=O(n^(d)).

关键词： Approximation bound Lasserre’s relaxation Polynomials Semidefinite programming Sum of squares

A MULTI-OBJECTIVE ROBUST OPERATION MODEL FOR ELECTRONIC MARKET ENABLED SUPPLY CHAIN WITH UNCERTAIN DEMANDS

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Journal of Systems Science and Systems Engineering 2007年第1期16卷 74-87页

作者： jiawang XU Xiaoyuan HUANG Nina YAN Management Department Shenyang Institute of Aeronautical Engineering Shenyang 110136 China School of Business Administration Northeastern University Shenyang 110004 China

A multi-objective robust operation model is proposed in this paper for an electronic market enablexi supply chain consisting of multi-supplier and multi-customer with uncertain demands. Suppliers in this supply chain provide many kinds of products to different customers directly or through electronic market. Uncertain demands are described as a scenario set with certain probability;, the supply chain operation model is constructed by using the robust optimization method based on scenario analyses. The operation model we proposed is a multi-objective programming problem satisfying several conflict objectives, such as meeting the demands of all customers, minimizing the system cost, the availabilities of suppliers＇ capacities not below a certain level, and robustness of decision to uncertain demands. The results of numerical examples proved that the solution of the model is most conservative; however, it can ensure the robustness of the operation of the supply chain effectively.

关键词： Operation management robust optimization objective programming electronic market

Phonon anharmonicity:a pertinent review of recent progress and perspective

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Science China(Physics,Mechanics & Astronomy) 2021年第11期64卷 10-43页

作者： Bin Wei Qiyang Sun Chen Li jiawang Hong Henan Key Laboratory of Materials on Deep-Earth Engineering School of Materials Science and EngineeringHenan Polytechnic UniversityJiaozuo 454000China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Department of Mechanical Engineering University of CaliforniaRiversideRiverside CA 92521USA Materials Science and Engineering University of CaliforniaRiversideRiverside CA 92521USA

Anharmonic lattice vibrations play pivotal roles in the thermal dynamics in condense matters and affect how the atoms interact and conduct *** in-depth understanding of the microscopic mechanism of phonon anharmonicity in condensed systems is critical for developing better functional and energy *** recent years,various novel behaviors in condense matters driven by phonon anharmonic effects were discovered,such as soft mode phase transition,negative thermal expansion(NTE),multiferroicity,ultralow thermal conductivity(κ),high thermal resistance,and high-temperature *** properties have endowed anharmonicity with many promising applications and provided remarkable opportunities for developing“Anharmonicity Engineering”-regulating heat transport towards excellent performance in *** this work,we review the recent development of studies on phonon anharmonic effect and summarize its origin,mechanism,research methods,and ***,the remaining challenges,future trends,and prospects of phonon anharmonicity are also discussed.

关键词： phonon phonon anharmonicity thermodynamics inelastic neutron/X-ray scattering

Development of underwater electric manipulator based on interventional autonomous underwater vehicle (AUV)

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第3期25卷 238-250页

作者： Xiaohui HU jiawang CHEN Hang ZHOU Ziqiang REN Ocean cllege Zhejiang UniversityZhoushan 316021China Hainan Institute Zhejiang UniversitySanya 572025China The Engineering Research Center of Oceanic Sensing Technology and Equipment Ministry of EducationZhoushan 316021China

In applications such as marine rescue,marine science,archaeology,and offshore industries,autonomous underwater vehicles(AUVs)are frequently used for survey missions and monitoring tasks,with most operations being performed by manned submersibles or remotely operated vehicles(ROVs)equipped with robotic arms,as they can be operated remotely for days without ***,they require expensive marine vessels and specialist pilots to operate *** exploring oceans are no longer satisfied with the use of manned submersibles and *** is a growing desire for seabed exploration to be performed using smarter,more flexible,and automated *** improving the field operation and intervention capability of AUVs,large-scale and long-range seafloor exploration and sampling can be performed without the support of a mother ship,making it a more effective,economical,convenient,and rapid means of seafloor exploration and sampling operations,and playing a critical role in marine resource *** this study,we explored the integration technology of underwater electric robotic arms and AUVs and designed a new set of electric manipulators suitable for water depths greater than 500 *** reliability of the key components was analyzed by finite element analysis and,based on the theory of robot kinematics and dynamics,simulations were performed to verify the reliability of the key *** were conducted on land and underwater,trajectory tracking experiments were completed,and the experimental data in air and water were compared and ***,the objectives for further research on the autonomous control of the manipulator underwater were proposed.

关键词： Underwater electric manipulator Inverse kinematics Trajectory planning Trajectory tracking accuracy

Static mechanics analysis of no bumping no vibration welding structure with double-inclined surface for high-speed & heavy-load CWR

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Science China(Technological Sciences) 2011年第3期54卷 603-609页

作者： SONG YuQuan WANG MingHui SONG jiawang Superplasticity and Plasticity Research Institute Jilin University Changchun 130022 China

It is known from our former theoretical analysis that the single-inclined welding surface which is inclined towards the transverse direction of the rail can only eliminate vertical bumping, and the single-inclined welding surface which is inclined towards the vertical direction of the rail can only eliminate lateral vibration. In this paper, we put forward a welding structure of double-inclined welding surface to eliminate the vertical bumping and lateral vibration at the same time, and analyze the stress state of continuous welded rail (CWR) by combining geometrical azimuth. Furthermore, the increase of bearing capacity of CWR with the double-inclined welding surface is theoretically analyzed.

关键词： continuous welded rail double-inclined welding surface bearing capacity regularity

Atomic-scale simulations for lithium dendrite growth driven by strain gradient

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Applied Mathematics and Mechanics(English Edition) 2020年第4期41卷 533-542页

作者： Gao XU Feng HAO jiawang HONG Daining FANG State Key Laboratory for Turbulence and Complex Systems&Center for Applied Physics and Technology College of EngineeringPeking UniversityBeijing 100871China Department of Engineering Mechanics Shandong UniversityJinan 250100China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

Dendrite formation is a major obstacle, e.g., capacity loss and short circuit,to the next-generation high-energy-density lithium(Li)-metal batteries. The development of successful Li dendrite mitigation strategies is impeded by an insu?cient understanding in Li dendrite growth mechanisms. The Li-plating-induced internal stress in Li-metal and its e?ects on dendrite growth have been widely studied, but the underlying microcosmic mechanism is elusive. In the present study, the role of the plating-induced stress in dendrite formation is analyzed through ?rst-principles calculations and ab initio molecular dynamic(AIMD) simulations. It is shown that the deposited Li forms a stable atomic nano?lm structure on the copper(Cu) substrate, and the adsorption energy of Li atoms increases from the Li-Cu interface to the deposited Li surface, leading to more aggregated Li atoms at the interface. Compared with the pristine Li-metal, the deposited Li in the early stage becomes compacted and su?ers the in-plane compressive stress. Interestingly,there is a giant strain gradient distribution from the Li-Cu interface to the deposited Li surface, making the deposited atoms adjacent to the Cu surface tend to press upwards with perturbation and causing the dendrite growth. This provides an insight into the atomicscale origin of Li dendrite growth, and may be useful for suppressing the Li dendrite in Li-metal-based rechargeable batteries.

关键词： lithium(Li)-metal-based battery Li dendrite strain gradient depositing

Preparation of Spherical Tungsten Particles Assisted by Hydrothermal Method

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1457-1462页

作者： GUO jiawang WEN Xiaoqiang WU Ying XU Jianbing ZHOU Jieying Ganzhou Nonferrous Metallurgy Research Institute Co. LtdGanzhou 341000China

We presented a strategy to prepare spherical tungsten powder by the combination of hydrothermal method and H2reduction *** hydrothermal process,the micelle of tetraethylammonium bromide(TEAB)act as spherical templates for the deposition of tungsten oxide,whereas the excessive TEAB inhibit the formation of spherical tungsten oxide due to the dense molecular layer of TEAB on the tungsten oxide *** acid(CA)can control the formation rate and structure of the tungsten oxide when its concentration is more than 0.2 mol/L,because of its ability to coordinate with tungsten *** synergistic effect of TEAB and CA facilitates the formation of spherical tungsten oxide with nanorod *** being treated by H_(2)at 600 and 650℃,the tungsten oxide particles are reduced to tungsten particles,which maintain the spherical structure of tungsten oxide and have porous structure.

关键词： spherical tungsten particles spherical tungsten oxide hydrothermal method citric acid tetraethylammonium bromide

Light-Activated Virtual Sensor Array with Machine Learning for Non-Invasive Diagnosis of Coronary Heart Disease

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Nano-Micro Letters 2024年第12期16卷 427-448页

作者： jiawang Hu Hao Qian Sanyang Han Ping Zhang Yuan Lu Department of Chemical Engineering Tsinghua UniversityBeijing 100084People’s Republic of China Key Laboratory of Industrial Biocatalysis Ministry of EducationTsinghua UniversityBeijing 100084People’s Republic of China Department of Cardiology Xuanwu HospitalCapital Medical UniversityBeijing 100053People’s Republic of China Department of Cardiology Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijing 102218People’s Republic of China Institute of Biopharmaceutical and Health Engineering Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055People’s Republic of China

Early non-invasive diagnosis of coronary heart disease(CHD)is ***,it is challenging to achieve accurate CHD diagnosis via detecting *** this work,heterostructured complexes of black phosphorus(BP)and two-dimensional carbide and nitride(MXene)with high gas sensitivity and photo responsiveness were formulated using a self-assembly strategy.A light-activated virtual sensor array(LAVSA)based on BP/Ti_(3)C_(2)Tx was prepared under photomodulation and further assembled into an instant gas sensing platform(IGSP).In addition,a machine learning(ML)algorithm was introduced to help the IGSP detect and recognize the signals of breath samples to diagnose *** to the synergistic effect of BP and Ti_(3)C_(2)Tx as well as photo excitation,the synthesized heterostructured complexes exhibited higher performance than pristine Ti_(3)C_(2)Tx,with a response value 26%higher than that of pristine Ti_(3)C_(2)*** addition,with the help of a pattern recognition algorithm,LAVSA successfully detected and identified 15 odor molecules affiliated with alcohols,ketones,aldehydes,esters,and ***,with the assistance of ML,the IGSP achieved 69.2%accuracy in detecting the breath odor of 45 volunteers from healthy people and CHD *** conclusion,an immediate,low-cost,and accurate prototype was designed and fabricated for the noninvasive diagnosis of CHD,which provided a generalized solution for diagnosing other diseases and other more complex application scenarios.

关键词： Black phosphorus/MXene heterostructures Light-activated virtual sensor array Diagnosis of coronary heart disease Machine learning

Mechanical Properties of Formamidinium Halide Perovskites FABX_3(FA=CH(NH_2)_2; B=Pb, Sn; X=Br, I) by First-Principles Calculations

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Chinese Physics Letters 2019年第5期36卷 44-48页

作者： Lei Guo Gang Tang jiawang Hong School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081

The mechanical properties of formamidinium halide perovskites FABX_3(FA=CH(NH_2)_2; B=Pb, Sn; X=Br, I)are systematically investigated using first-principles calculations. Our results reveal that FABX_3 perovskites possess excellent mechanical flexibility, ductility and strong anisotropy. We shows that the planar organic cation FA+ has an important effect on the mechanical properties of FABX3 perovskites. In addition, our results indicate that (i) the moduli(bulk modulus B, Young's modulus E, and shear modulus G) of FABBr_3 are larger than those of FABI_3 for the same B atom, and (ii) the moduli of FAPbX_3 are larger than those of FASnX_3 for the same halide atom. The reason for the two trends is demonstrated by carefully analyzing the bond strength between B and X atoms based on the projected crystal orbital Hamilton population method.

关键词： FA=CH Sn Mechanical Properties of Formamidinium Halide Perovskites FABX3 by First-Principles Calculations B FA CH