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Two Constructions of Optimal Cartesian Authentication Codes from Unitary Geometry over Finite Fields

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Acta Mathematicae Applicatae Sinica 2013年第4期29卷 829-836页

作者： shang-di CHEN Da-wei ZHAO College of Science Civil Aviation University of China Information Security Center Beijing University of Posts and Telecommunications

Two constructions of cartesian authentication codes from unitary geometry are given in this paper. Their size parameters and their probabilities of successful impersonation attack and successful substitution attack ar... 详细信息

关键词： unitary geometry optimal authentication code finite field

Provenance of Central Canyon in Qiongdongnan Basin as evidenced by detrital zircon U-Pb study of Upper Miocene sandstones

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Science China Earth Sciences 2015年第8期58卷 1337-1349,1-6页

作者： CHEN Hui XIE XiNong GUO JingLiang SU Ming ZONG KeQing shang Fei HUANG wei WANG wei shang ZhiLei Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education Faculty of ResourcesChina University of Geosciences State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Key Laboratory of Renewable Energy and Gas Hydrate Guangzhou Institute of Energy ConversionChinese Academy of Sciences China National Offshore Oil Corporation Research Institute

Deep-water canyon systems can provide important sandstone reservoirs for deep-water oil and gas exploration in the South China Sea;however,the sedimentary provenance of the Central Canyon in the Qiongdongnan Basin remains *** this work,detrital zircon grains from three drilling sandstones in the Upper Miocene Huangliu Formation in the western part of the Central Canyon were analysed by LA-ICP-MS for U-Pb ages,in order to constrain their *** hundred and ninety-one zircon grains yield concordant U-Pb ages ranging from 28.6 to 3285 *** of them show oscillatory or linear zoning in CL-images and high Th/U ratios(>0.1),suggesting that they are magmatic *** major age clusters at about30 Ma(N=6),220–270 Ma(N=29),and 420–440 Ma(N=13),and five minor age clusters at 70–110 Ma(N=7),150–170 Ma(N=4),800–850 Ma(N=11),1800–2000 Ma(N=16),and 2400–2600 Ma(N=7),can be identified in the age spectrum,which are very similar to those of the Upper Miocene sandstones and modern river sands in the Red River area,but different from those of other nearby regions(e.g.,Hainan Island,the Pearl River area,and the Mekong River area)in Southeast *** major age peak at about 30 Ma in our samples is consistent with the timing of tectonothermal events in the Red River Fault ***,we suggest that the provenance of the western part of the Central Canyon,in the Qiongdongnan Basin,was fed dominantly by the Paleo-Red River system during the Late Miocene.

关键词： Qiongdongnan Basin Central Canyon detrital zircon U-Pb dating LA-ICP-MS sedimentary provenance

Robust controller design for compound control missile with fixed bounded convergence time

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Journal of Systems Engineering and Electronics 2018年第1期29卷 116-133页

作者： YUN Yuhang TANG Shengjing GUO Jie shang wei School of Aerospace Engineering Beijing Institute of Technology

A robust controller for bank to turn(BTT) missiles with aerodynamic fins and reaction jet control system(RCS) is developed based on nonlinear control dynamic models comprising couplings and aerodynamic uncertainties. The fixed time convergence theory is incorporated with the sliding mode control technique to ensure that the system tracks the desired command within uniform bounded time under different initial conditions. Unlike previous terminal sliding mode approaches, the bound of settling time is independent of the initial state, which means performance metrics like convergence rate can be predicted beforehand. To reduce the burden of control design in terms of robustness, extended state observer(ESO) is introduced for uncertainty estimation with the output substituted into the controller as feedforward compensation. Cascade control structure is employed with the proposed control law and therein the compound control signal is ***, control inputs for two kinds of actuators are allocated on the basis of their inherent characteristics. Finally, a number of simulations are carried out and demonstrate the effectiveness of the designed controller.

关键词： reaction jet control compound control fixed bounded convergence time sliding mode control extended state observer(ESO)

Effects of sludge dredging on the prevention and control of algae-caused black bloom in Taihu Lake,China

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Journal of Environmental Sciences 2013年第3期25卷 430-440页

作者： wei He Jingge shang Xin Lu Chengxin Fan State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of Sciences University of Chinese Academy of Sciences

Algae-caused black bloom （also known as black water agglomerate） has recently become a critical problem in some Chinese *** has been suggested that the occurrence of algae-caused black bloom was caused by the cooperation of nutrient-rich sediment with dead algae,and sludge dredging was adopted to control black bloom in some lakes of *** this article,based on the simulation of black bloom using a Y-shape apparatus for modeling natural conditions,both un-dredged and dredged sites in three areas of Taihu Lake,China were studied to estimate the effects of dredging on the prevention and control of black *** the experiment,drained algae were added to all six sites as an additional organic load;subsequently,the dissolved oxygen decreased rapidly,dropping to 0 mg/L at the sediment-water *** bloom did not occur in the dredged sites of Moon Bay and Nan Quan,whereas all three un-dredged sites at Fudu Port,Moon Bay and Nan Quan experienced black *** bloom also occurred at the dredged site of Fudu Port one day later than at the other sites,and the odor and color were lighter than at the other *** color and odor of the black water mainly result from the presence of sulfides such as metal sulfides and hydrogen sulfide,among other chemicals,under reductive *** color and odor of the water,together with the high concentrations of nutrients,were mainly caused by the decomposition of the algae and the presence of nutrient-rich ***,the removal of the nutrient-rich sediment by dredging can prevent the occurrence and control the degree of algae-caused black bloom in Taihu Lake.

关键词： Taihu Lake algae-caused black bloom sediment sludge dredging

Microstructural Evolution and Cracking of Pb-free Ball Grid Array Assemblies under Thermal Cycling

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Journal of Materials Science & Technology 2007年第1期23卷 85-91页

作者： wei WANG Zhongguang WANG Aiping XIAN Jianku shang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

Two kinds of CBGA （ceramic ball grid array） assemblies were made by reflow soldering process using two different Pb-free solders. Microstructural evolution and cracks induced by thermal cycling in CBGA assemblies were examined by scanning electron microscopy （SEM） and finite element method （FEM）. Before thermal cycling, intermetallic compounds （IMCs） Cu6Sn5 and Ag3Sn were observed at the solder interface between Cu and Ag metallizations, respectively. After thermal cycling, another IMC Cu3Sn was observed near the Cu pad in both two assemblies and the layers of Cu6Sn5 and Ag3Sn became thicker. As a result of thermal cycling, cyclic stress and strain were accumulated in the solder joint leading to fatigue cracking. Both experiments and FEM revealed that cracks preferred to initiate at the corner of each solder joint. Multi-modes of the crack propagation were found in the two assemblies. Based on Coffin-Manson equation, the thermal fatigue life was calculated and the predicted life showed good agreement with the experimental results.

关键词： CBGA Thermal cycling FEM Assembly Cracking

Computational Path Planner for Product Assembly in Complex Environments

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Chinese Journal of Mechanical Engineering 2013年第2期26卷 282-292页

作者： shang wei LIU Jianhua NING Ruxin LIU Mi School of Mechanical Engineering Beijing Institute of Technology

Assembly path planning is a crucial problem in assembly related design and manufacturing processes. Sampling based motion planning algorithms are used for computational assembly path planning. However, the performance of such algorithms may degrade much in environments with complex product structure, narrow passages or other challenging scenarios. A computational path planner for automatic assembly path planning in complex 3D environments is presented. The global planning process is divided into three phases based on the environment and specific algorithms are proposed and utilized in each phase to solve the challenging issues. A novel ray test based stochastic collision detection method is proposed to evaluate the intersection between two polyhedral objects. This method avoids fake collisions in conventional methods and degrades the geometric constraint when a part has to be removed with surface contact with other parts. A refined history based rapidly-exploring random tree （RRT） algorithm which bias the growth of the tree based on its planning history is proposed and employed in the planning phase where the path is simple but the space is highly constrained. A novel adaptive RRT algorithm is developed for the path planning problem with challenging scenarios and uncertain environment. With extending values assigned on each tree node and extending schemes applied, the tree can adapts its growth to explore complex environments more efficiently. Experiments on the key algorithms are carried out and comparisons are made between the conventional path planning algorithms and the presented ones. The comparing results show that based on the proposed algorithms, the path planner can compute assembly path in challenging complex environments more efficiently and with higher success. This research provides the references to the study of computational assembly path planning under complex environments.

关键词： assembly path planning motion planning stochastic collision detection rapidly-exploring random tree adaptive RRT

Integrated Virtual Assembly Process Planning System

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Chinese Journal of Mechanical Engineering 2009年第5期22卷 717-728页

作者： LIU Jianhua HOU weiwei shang wei NING Ruxin School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China

Assembly process planning（APP） for complicated products is a time-consuming and difficult work with conventional method. Virtual assembly process planning（VAPP） provides engineers a new and efficiency way. Previous studies in VAPP are almost isolated and dispersive, and have not established a whole understanding and discussed key realization techniques of VAPP from a systemic and integrated view. The integrated virtual assembly process planning（IVAPP） system is a new virtual reality based engineering application, which offers engineers an efficient, intuitive, immersive and integrated method for assembly process planning in a virtual environment. Based on analysis the information integration requirement of VAPP, the architecture of IVAPP is proposed. Through the integrated structure, IVAPP system can realize information integration and workflow controlling. In order to mode/the assembly process in IVAPP, a hierarchical assembly task list（HATL） is presented, in which different assembly tasks for assembling different components are organized into a hierarchical list. A process-oriented automatic geometrical constraint recognition algorithm（AGCR） is proposed, so that geometrical constraints between components can be automatically recognized during the process of interactive assembling. At the same time, a progressive hierarchical reasoning（PHR） model is discussed. AGCR and PHR will greatly reduce the interactive workload. A discrete control node model（DCNM） for cable harness assembly planning in IVAPP is detailed. DCNM converts a cable harness into continuous flexed line segments connected by a series of section center points, and designs can realize cable harness planning through controlling those control nodes. Mechanical assemblies （such as transmission case and engine of automobile） are used to illustrate the feasibility of the proposed method and algorithms. The application of IVAPP system reveals advantages over the traditional assembly process planning method in

关键词： virtual assembly assembly model assembly task collision detection automatic constraint recognition cable harness assembly process planning

Role of Wetting Front in Dewetting of Liquid Solder Drop on Cu Thin Films

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Journal of Materials Science & Technology 2010年第3期26卷 200-205页

作者： wei Liu Lei Zhang J.K. shang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

The thermodynamic conditions for dewetting of a liquid solder drop on copper thin films were examined under a hot-stage optical microscope in a flowing protective *** of liquid solder was found to depend strongly on the copper film thickness and preceded by spalling of Cu 6 Sn 5 intermetallic ***,the loss of interfacial bonding by spalling was not sufficient to cause immediate dewetting of solder drops if the wetting tip was still strongly bonded to the copper *** introducing a pinning force on the wetting front,a sufficient condition was found from a force balance analysis for dewetting of the liquid solder drop,in general agreement with the experimental results.

关键词： Dewetting Solder Spalling Film thickness

Dynamic Shortest Path Monitoring in Spatial Networks

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Journal of Computer Science & Technology 2016年第4期31卷 637-648页

作者： Shuo shang Lisi Chen Zhe-wei wei Dan-Huai Guo Ji-Rong Wen State Key Laboratory of Software Development Environment Beijing 100191 China Department of Computer Science China University of Petroleum Beijing 102249 China School of Computer Engineering Nanyang Technological University Singapore 639798 Singapore Beijing Key Laboratory of Big-Data Management and Analysis Methods Renmin University of China Beijing 100080 China Computer Network Information Center Chinese Academy of Sciences Beijing 100190 China

With the increasing availability of real-time traffic information, dynamic spatial networks are pervasive nowa- days and path planning in dynamic spatial networks becomes an important issue. In this light, we propose and investigate a novel problem of dynamically monitoring shortest paths in spatial networks （DSPM query）. When a traveler aims to a des- tination, his/her shortest path to the destination may change due to two reasons： 1） the travel costs of some edges have been updated and 2） the traveler deviates from the pre-planned path. Our target is to accelerate the shortest path computing in dynamic spatial networks, and we believe that this study may be useful in many mobile applications, such as route planning and recommendation, car navigation and tracking, and location-based services in general. This problem is challenging due to two reasons： 1） how to maintain and reuse the existing computation results to accelerate the following computations, and 2） how to prune the search space effectively. To overcome these challenges, filter-and-refinement paradigm is adopted. We maintain an expansion tree and define a pair of upper and lower bounds to prune the search space. A series of optimization techniques are developed to accelerate the shortest path computing. The performance of the developed methods is studied in extensive experiments based on real spatial data.

关键词： shortest path dynamic spatial network spatial database location-based service