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PARTITION OF UNITY FINITE ELEMENT METHOD FOR SHORT WAVE PROPAGATION IN SOLIDS

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Applied Mathematics and Mechanics(English Edition) 2005年第8期26卷 1056-1063页

作者： LI xi-kui（李锡夔） ZHOU Hao-yang（周浩洋） State Key Laboratory for Structural Analysis of Industrial Equipment Dalian University of Technology Dalian 116024 P. R. China

A partition of unity finite element method for numerical simulation of short wave propagation in solids is presented. The finite element spaces were constructed by multiplying the standard isoparametric finite element shape functions, which form a partition of unity, with the local subspaces defined on the corresponding shape functions, which include a priori knowledge about the wave motion equation in trial spaces and approximately reproduce the highly oscillatory properties within a single element. Numerical examples demonstrate the performance of the proposed partition of unity finite element in both computational accuracy and efficiency.

关键词： short wave propagation solid continuum partition of unity finite element method

Toward Privacy-Preserving Personalized Recommendation Services

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Engineering 2018年第1期4卷 21-28页

作者： CongWang Yifeng Zheng Jinghua jiang kui Ren Department of Computer Science City University of Hong Kong Hong Kong China City University of Hong Kong Shenzhen Research Institute Shenzhen Guangdong 518057 China Department of Computer Science and Technology Xi'an fiaotong University Xi'an 710049 China Institute of Cyber Security Research Zhejiang University Hangzhou Zhejiang 310058 China

Recommendation systems are crucially important for the delivery of personalized services to users. With personalized recommendation services, users can enjoy a variety of targeted recommendations such as movies, hooks, ads, restaurants, and more. In addition, personalized recommendation services have become extremely effective revenue drivers for online business. Despite the great benefits, deploying per- sonalized recommendation services typically requires the collection of users＇ personal data for processing and anafytics, which undesirably makes users susceptible to serious privacy violation issues. Therefore, it is of paramount importance to develop practical privacy-preserving techniques to maintain the intelligence of personalized recommendation services while respecting user privacy. In this paper, we provide a comprehensive survey of the literature related to personalized recommendation services with privacy protection. We present the general architecture of personalized recommendation systems, the privacy issues therein, and existing works that focus on privacy-preserving personalized recommendation services. We classify the existing works according to their underlying techniques for personalized recommendation and privacy protection, and thoroughly discuss and compare their merits and demerits, especially in terms of privacy and recommendation accuracy. We also identity some future research directions.

关键词： Privacy protectionPersonalized recommendation servicesTargeted deliveryCollaborative filteringMachine learning

Effects of UV-B radiation on the growth interaction of Ulva pertusa and Alexandrium tamarense

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Journal of Environmental Sciences 2005年第4期17卷 605-610页

作者： CAIHeng-jiang TANGXue-xi ZHANGPei-yu MarineEcologyLaboratory OceanUniversityofChinaQingdao266003China MarineEcologyLaboratory OceanUniversityofChinaQingdao266003China／／DepartmentofEnvironmentalScienceandEngineeringQingdaoUniversityQingdao266071China

Enhanced UV-B(280-320 nm) radiation resulting from ozone depletion is one of global environmental problems. Not only marine organisms but also marine ecosystems can be affected by enhanced UV-B radiation. The effects of UV-B radiation on interaction of macro-algae and micro-algae were investigated using Ulva pertusa Kjellman and Alexandrium tamarense as the materials in this study. The results demonstrated that UV-B radiation could inhibit the growth of Ulva pertusa and Alexandrium tamarense when they were both mono-cultured, and the growth inhibition of algae was more significant with increasing doses of UV-B radiation. Alexandrium tamarense could inhibit the growth of Ulva pertusa in mixed culture, and the growth inhibition was more significant when increasing the initial cell density. However, Ulva pertusa could inhibit the growth of Alexandrium tamarense in early phase and stimulate the growth in latter phase when they were grown in mixed culture. Lower initial cell density(10~2 cell/ml) of Alexandrium tamarense could inhibit the growth of Ulva pertusa under UV-B radiation treatment,however, with the initial cell density increasing(10~3 and 10~4 cell/ml), the growth of Ulva pertusa was stimulated under lower dose of UV-B radiation and inhibited under higher dose of UV-B radiation by Alexandrium tamarense. Compared with that in mixed culture, Ulva pertusa showed more positive inhibition to the growth of Alexandrium tamarense under UV-B radiation treatment.

关键词： UV-B radiation mono-culture mixed culture Ulva pertusa Alexandrium tamarense growth

Modular Precoding Based on Zero Forcing in Large Scale Antenna Systems with Imperfect Channel State Information

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Chinese Journal of Electronics 2017年第2期26卷 424-429页

作者： xi Qi HE Chen jiang Lingge Department of Electronic Engineering Shanghai Jiaotong University National Mobile Communications Research Laboratory Southeast University

In Large scale antenna systems(LSAS),the user number is usually much less than the number of base station *** leveraging this characteristic,Modular precoding based on zero forcing(MZF) is proposed to achieve higher spectrum efficiency than Maximum ratio combining(MRC),while preserve the advantage of distributive *** achievable rates of the MZF,MRC and Zero forcing(ZF) are derived under the generalized model of imperfect Channel state information(CSI).The imperfect CSI model includes the channel estimation delay,the noise in the pilot channel,and the pilot *** analytical achievable rates match the simulations even with a small number of base station *** the antenna number approaches to infinity,the analytical achievable rates of MZF converge to the analytical achievable rates of ZF.

关键词： Modular precoding based on zero forcing Capacity analysis Imperfect CSI Large scale antenna systems

The influence of hand hole on the ultimate strength and crack pattern of shield tunnel segment joints by scaled model test

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Frontiers of Structural and Civil Engineering 2019年第5期13卷 1200-1213页

作者： Shaochun WANG xi jiang Yun BAI Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

With the shield tunnel going deeper and deeper, the circumferential axial force becomes the governing factor rather than the bending moment. The hand hole acts as a weak point and initial damage in the segment joint especially when the circumferential axial force is extremely high. Despite the wide application of steel fiber or synthetic fiber in t|ie tunneling, limited researches focus on the structural responses of segment joint with macro structural synthetic fiber (MSSF). In this paper, a 1:2 reduced-scale experiment was conducted to study the structural perfonnance of the segment joint with different types of hand holes under ultra-high axial force. Special attention is paid to failure mode and structural performance (bearing capacity, deformation, cracking, and toughness). Moreover, segment joints with MSSF are also tested to evaluate the effects of MSSF on the failure mode and structural performance of the segment joints. The experiment results show that the hand hole becomes the weakest point of the segment joint under ultra-high axial force. A\/-type crack pattern is always observed before the final failure of the segment joints. Different types and sizes of the hand hole have different degree of influences on the structural behavior of segment joints. The segment joint with MSSF shows higher ultimate bearing capacity and toughness compared to segment joint with common concrete. Besides, the MSSF improves the initial cracking load and anti-spallling resistance of the segment joint.

关键词： shield tunneling structural synthetic fiber concrete hand hole segment joint ultimate bearing capacity crack pattern

Period-doubling bifurcation in two-stage power factor correction converters using the method of incremental harmonic balance and Floquet theory

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Chinese Physics B 2012年第2期21卷 153-162页

作者： Wang Fa-Qiang Zhang Hao Ma xi-kui State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical EngineeringXi'an Jiaotong UniversityXi'an 710049China

In this paper, period-doubling bifurcation in a two-stage power factor correction converter is analyzed by using the method of incremental harmonic balance （IHB） and Floquet theory. A two-stage power factor correction converter typically employs a cascade configuration of a pre-regulator boost power factor correction converter with average current mode control to achieve a near unity power factor and a tightly regulated post-regulator DC-DC Buck converter with voltage feedback control to regulate the output voltage. Based on the assumption that the tightly regulated postregulator DC-DC Buck converter is represented as a constant power sink and some other assumptions, the simplified model of the two-stage power factor correction converter is derived and its approximate periodic solution is calculated by the method of IHB. And then, the stability of the system is investigated by using Floquet theory and the stable boundaries are presented on the selected parameter spaces. Finally, some experimental results are given to confirm the effectiveness of the theoretical analysis.

关键词： two-stage power factor correction converter incremental harmonic balance Floquet theory period-doubling bifurcation

Structural safety criteria for blasting vibration based on wavelet packet energy spectra

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Mining Science and Technology 2011年第1期21卷 35-40页

作者： Zhong Guosheng Li jiang Zhao kui School of Resources ＆ Environmental Engineering Jiangxi University of Science ＆ Technology Ganzhou 341000 China School of Civil ＆ Transportation South China University of Technology Guangzhou 510641 China

Given multi-resolution decomposition of wavelet packet transforms,wavelet packet frequency band energy has been deduced from different bands of blasting vibration *** deduction reflects the total effect of all three key elements（intensity,frequency and duration of vibration）of blasting vibration. We considered and discuss the dynamic response of structures and the effect of inherent characteristics of controlled structures to blasting *** band response coefficients for controlled structures by blasting vibration have been *** established multi-factor blasting vibration safety criteria,referred to as response energy *** criteria reflect the total effect of intensity, frequency and duration of vibration and the inherent characteristics（natural frequency and damping ratio）of dynamic responses from controlled structures *** and reliability of the criteria are validated by an example.

关键词： Blasting vibrationWavelet packet transformResponse energySafety criteria

Characteristics of biomarkers in source rocks of the Ganquan Formation in the Dahulishan region, Ejina Banner

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Chinese Journal Of Geochemistry 2013年第3期32卷 313-320页

作者： SU kui TANG Youjun jiang xingchao CHEN Jianfa Institute of Mineral Resources Chinese Academy of Geological Sciences Key Laboratory of Exploration Technologies for Oil and Gas Resources Ministry of Education Department of Geochemistry Yangtze University State Key Laboratory of Petroleum Resource and Prospecting China University of Petroleum

Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors examined biomarker characteristics of the Ganquan Formation source rocks in the area of Dahulishan, Ejina, and analyzed the information and petroleum geological significance that were indicated by the source of organic matter, sedimentary environment and maturity and so on. Gas chromatography peak of saturated hydrocarbons from the Ganquan Formation source rocks showed "the former peak" of the single peak distribution, the main peak of carbon being C18 , indicating the main sources of organic matter with marine organic matter. Pr/Ph ranges from 0.3 to 0.6, indicating a strongly reducing sedimentary environment. Biomarker assemblages of the Ganquan Formation source rocks are abundant in tricyclic terpane with long side chains, with a high level of gammacerane, showing dominant distribution of C27 sterane. High contents of gammacerane in organic matter show organic facies of source rocks in the saltwater sedimentary environment. That average hopane/sterane ratio is 0.59, showing that algae have made more contributions to organic matter than bacteria. And the high level of C27 steranes shows that algae are the main source of hydrocarbon precursors. The Ganquan Formation's methylphenanthrene index, which is an effective molecular parameter index to measure thermal evolution of organic matter, ranges from 0.35 to 0.50, and the conversion of vitrinite reflectance Rc from it is within the range of 2.00-2.09, indicating that the Ganquan Formation source rocks are in the over-mature stage of thermal evolution.

关键词：生物标志物额济纳旗烃源岩有机质热演化气相色谱法有机物质特征石油地质意义

Experimental study of drag reduction in flumes and spillway tunnels

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Water Science and Engineering 2010年第2期3卷 200-207页

作者： Ying-kui WANG Chun-bo jiang State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 P. R. China

Experiments in an open flume model and spillway tunnel model were carried out using drag reduction techniques. Two drag reduction techniques were adopted in the experiments： polymer addition and coating. The drag reduction effect of a polyacrylamide （PAM） solution and dimethyl silicone oil coating were studied in the flume model experiments, and the results were analyzed. Experiments were then carded out with a model of the xilnodu Hydropower Station, the second largest dam in China. In order to reduce the resistance, the spillway tunnels were internally coated with dimethyl silicone oil. This is the first time that these drag reduction techniques have been applied to so large a hydraulic model. The experimental results show that the coating technique can effectively increase flood discharge. The outlet velocity and the jet trajectory distance are also increased, which enhances the energy dissipation of the spillway tunnel.

关键词： drag reduction hydraulic model experiment spillway tunnel