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THE BOUNDARY INTEGRO-DIFFERENTIAL EQUATIONS OF A BIHARMONIC BOUNDARY VALUE PROBLEM

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Journal of Computational Mathematics 1999年第1期17卷 59-72页

作者： Ban, HD Tang, WJ Inst Appl Phys & Computat Math Lab Computat Phys Beijing 100088 Peoples R China Tsing Hua Univ Dept Appl Math Beijing 100084 Peoples R China

In this paper, a new method of boundary reduction is proposed, which reduces the biharmonic boundary value problem to a system of integro-differential equations on the boundary and preserves the self-adjointness of the original problem. Moreover, a boundary finite element method based on this integro-differential equations is presented and the error estimates of the numerical approximations are given. The numerical examples show that this new method is effective.

关键词： boundary integro-differential equations biharmonic boundary value problem

Frequent mtDNA mutations and its role in gastric carcino-genesis

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Chinese Science Bulletin 2002年第20期47卷 1720-1724页

作者： Manran Liu Youyong Lu Peking Univ Sch Oncol Beijing Inst Canc Res Beijing Lab Mol Oncol Beijing 100034 Peoples R China

In order to disclose the relationship between mutations of mitochondrial DNA (mtDNA) and gastric car-cinogenesis, we screened the entire mtDNA sequence in 30 cases of human gastric cancer and matched normal tissues by using denaturing high-performance liquid chromatogra-phy (DHPLC) and DNA sequencing. Our data showed that high frequency (66.7%, 20/30) of mitochondrial genome mutation occurred in gastric cancer. Among these variants, 17 cases (56.7%, 17/30) were identified to be somatic mutation. High level mutant frequency was found in ND4, ND5 coding genes and D-loop control region, which was 36.7%, 26.7% and 30% respectively. Comparing with complexes Ⅲ, Ⅳ and V of the electron transport chain, we found that variants appeared to be more frequent in the subunit genes of complex I. Most of mutations were base substitutions (85.4%, 41/48). Our results suggested that mutations of subunit genes encoding complex I, especially MM, ND4 and ND5 genes, might contribute to human gastric carcinogenesis.

关键词： mtDNA human gastric cancer gene mutation DHPLC gastric carcinogenesis.

Light People:*** Bowers spoke about silicon photonics

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Light(Science & Applications) 2022年第12期11卷 2843-2848页

作者： Chenzi Guo Yating Wan Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchunChina Integrated Photonics lab King Abdullah University of Science and TechnologyThuwalMakkah

Editorial Silicon photonics is advancing rapidly with many scientific and engineering advances and many new applications for *** highlight the topic,Light:Science&Applications invited John Bowers,director of the Institute for Energy Efficiency and distinguished professor from the University of California,Santa Barbara,to talk about the fundamentals and industries,and give a future perspective of silicon *** below is summarized from the video interview of *** original interview can be accessed in Supplementary video.

关键词： Efficiency interview photonics

Optical Properties of *** and Nanosaws Synthesized by Thermal Evaporation Method

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Chinese Journal of Chemical Physics 2012年第2期25卷 226-230,I0004页

作者： Zhi-wei Peng Bing-suo Zou School of Physics and Electronic Engineering Guangzhou UniversityGuangzhou 510006China Key lab for Micro-Nano Optoeletronic Devices of MOE Hunan UniversityChangsha 410082China

By a simple one-step H2-assisted thermal evaporation method, high quality CdS nanos- tructures have been successfully fabricated on Au coated Si substrates in large scale. The as-synthesized CdS nanostructures consisted of sword-like nanobelts and toothed nanosaws with a single-crystal hexagonal wurtzite structure. The deposition temperature played an important role in determining the size and morphology of the CdS nanostruetures. A combination of vapor-liquid-solid and vapor-solid growth mechanisms were proposed to interpret the formation of CdS nanostructures. Photoluminescence measurement indicated that the nanobelts and nanosaws have a prominent green emission at about 512 nm, which is the band-to-band emission of CdS. The waveguide characteristics of both types of CdS nanos-truetures were observed and discussed.

关键词： CdS nanostructures Thermal evaporation Photoluminescence Optical waveguide

Effect of the endoparasitoid Campoletis chlorideae on phenoloxidase activity in Helicoverpa armigera hemo-lymph

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Chinese Science Bulletin 2001年第21期46卷 1797-1800页

作者： Lihong Yin Chenzhu Wang Junde Qin Chinese Acad Sci Inst Zool State Key Lab Integrated Management Pest Insects Beijing 100080 Peoples R China

Endoparasitoid wasps can develop inside permissive host due to their ability to overcome or to evade the host’s cellular and humoral immune response. Oviposition of Campoletis chlorideae (Hymenoptera: Ichneumonidae) in larvae of Helicoverpa armigera (Lepidoptera) was accompanied by inhibition of phenoloxidase (PO) activity and melanization reaction in host hemolymph in vitro. PO activity in host plasma was decreased about 83% 48 h post para-sitization. A similar result was found when the host insect was injected with 0.5 wasp equivalent calyx fluid. This indicated that the calyx fluid was concerned with suppression of PO activity after parasitization. Furthermore, the prophen-oloxidase (proPO) in host haemocytes could be activated by bovine trypsin in unparasitized insects, while it could not be activated in parasitized or calyx fluid-injected host. The results suggested that inhibition of PO activity by parasitization was related to the calyx fluid of Campoletis chlorideae, and the components of calyx

关键词： insect immunity phenoloxidase prophenoloxidase en- doparasitoid calyx fluid.

Cumulative activation in social networks

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Science China(Information Sciences) 2019年第5期62卷 108-128页

作者： Xiaohan SHAN Wei CHEN Qiang LI Xiaoming SUN Jialin ZHANG Department of Computer Science and Technology Tsinghua University Microsoft CAS Key lab of Network Data Science and Technology Institute of Computing TechnologyChinese Academy of Sciences University of Chinese Academy of Sciences

Most studies on influence maximization focus on one-shot propagation, i.e., the influence is propagated from seed users only once following a probabilistic diffusion model and users’ activation are determined via single cascade. In reality it is often the case that a user needs to be cumulatively impacted by receiving enough pieces of information propagated to her before she makes the final purchase decision. In this paper we model such cumulative activation as the following process: first multiple pieces of information are propagated independently in the social network following the classical independent cascade model, then the user will be activated(and adopt the product) if the cumulative pieces of information she received reaches her cumulative activation threshold. Two optimization problems are investigated under this framework: seed minimization with cumulative activation(SM-CA), which asks how to select a seed set with minimum size such that the number of cumulatively active nodes reaches a given requirement η; influence maximization with cumulative activation(IM-CA), which asks how to choose a seed set with fixed budget to maximize the number of cumulatively active nodes. For SM-CA problem, we design a greedy algorithm that yields a bicriteria O(ln n)-approximation when η = n, where n is the number of nodes in the network. For both SM-CA problem with η < n and IM-CA problem, we prove strong inapproximability results. Despite the hardness results, we propose two efficient heuristic algorithms for SM-CA and IM-CA respectively based on the reverse reachable set approach. Experimental results on different real-world social networks show that our algorithms significantly outperform baseline algorithms.

关键词： social networks cumulative activation influence maximization seed minimization

Water-Assisted Injection Molding System Based on Water Hydraulic Proportional Control Technique

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Chinese Journal of Mechanical Engineering 2010年第4期23卷 418-427页

作者： ZHOU Hua ZHANG Zengmeng GAO Yuan＇an YANG Huayong The State Key lab of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China Jiujiang Branch of 707 Research Institute China Shipbuilding Industry Corporation Jiujiang 332007 China

Water-assisted injection molding（WaiM）, an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savings and injection pressure control can not be .attained based on conventional valve control system. Moreover, the injection water can not be supplied directly by water hydraulic proportional control system. Poor efficiency and control performance are presented by current trial systems, which pressurize injection water by compressed air. In this paper, a novel water hydraulic system is developed applying an accumulator for energy saving. And a new differential pressure control method is proposed by using pressure cylinder and water hydraulic proportional pressure relief valve for back pressure control. aiming at design of linear controller for injection water pressure regulation, a linear load model is approximately built through computational fluid dynamics（CFD） simulation on two-phase flow cavity filling process with variable temperature and viscosity, and a linear model of pressure control system is built with the load model and linearization of water hydraulic components. According to the simulation, model based feedback is brought forward to compensate the pressure decrease during accumulator discharge and eliminate the derivative element of the system. Meanwhile, the steady-state error can be reduced and the capacity of resisting disturbance can be enhanced, by closed-loop control of load pressure with integral compensation. Through the developed experimental system in the State Key lab of Fluid Power Transmission and Control, Zhejiang University, China, the static characteristic of the water hydraulic proportional relief valve was tested and output pressure control of the system in Acrylonitrile Butadiene Styrene（ABS） parts molding experiments was also studied. The experiment results show that the dead band and hysteresis of the water hydraulic propo

关键词： water-assisted injection molding water hydraulics proportional pressure control linear control load characteristic

Influence of Yttrium Addition on the Reduction Property of Tungsten Oxide Prepared via Wet Chemical Method

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Acta Metallurgica Sinica(English Letters) 2020年第2期33卷 275-280页

作者： Nan Liu Zhi Dong Zongqing Ma Zhu Qian Lei Ma Liming Yu Yongchang Liu State Key lab of Hydraulic Engineering Simulation and Safety School of Materials Science and EngineeringTianjin UniversityTianjin 300072China Tianjin Zhujin Technology Development Corporation Tianjin 300400China

W-Y2O3 composite nanopowders prepared via wet chemical method exhibit unique morphologies and micro *** yttrium addition during chemical reaction process affects not only the composition of tungsten acid hydrate precursors,but also the reduction property of tungsten oxide transformed from *** this study,the morphology evolution of the samples with and without yttrium during reduction process has been studied,and it is found that the addition of yttrium can exert a strong influence on the reduction route of tungsten oxide and the final morphology of tungsten *** cause of the difference of reduction route and tungsten particle morphology is also *** is suggested that the composition of the samples with yttrium at the beginning of reduction is pure cubic system WO3(c-WO3),and the c-WO3 particles have c-WO3 whiskers attached to the *** kind of whiskers is essential for c-WO3 to be reduced directly to tungsten and also helpful to obtain W-Y2O3 powders with small size and good uniformity.

关键词： W–Y2O3 nanopowders Wet chemical method Reduction property

Laser induced photoemission electron and the generation of high Rydberg states of atoms and molecules

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Chinese Science Bulletin 1998年第19期43卷 1616-1620页

作者： Li Wang Haiyang Li Jiling Bai Richang Lu Acad Sinica Dalian Inst Chem Phys State Key Lab Mol React Dynam Dalian 116023 Peoples R China

Laser induced photoemission electron was produced by directing 532 nm and/or 355 nm onto stainless steel plate on a time of flight mass spectrometer. Multiple charged ions and high Rydberg states of atoms or molecules were successfully generated by impacts of the photoemission electrons. The high Rydberg states ( n ～40-100) thus produced were separated from ions, produced by direct electron impact ionization, by a 3 V DC electric field and then ionized by a delayed pulsed HV electric field in a ZEKE-PFI manner. Relationship between generation/property of high Rydberg states of atoms/molecules and experimental conditions could be investigated. Relationship between the electron accelerating voltage and high Rydberg states of Ar was described.

关键词： photoemission electron multiple charged ions high Rydberg states.