A closed form solution to segment 3D motion using straight-line optical flow

A closed form solution to the problem of segmenting multiple 3D motion models was proposed from straight-line optical flow. It introduced the multibody line optical flow constraint （MLOFC）, a polynomial equation relating motion models and line parameters. The motion models can be obtained analytically as the derivative of the MLOFC at the corresponding line measurement, without knowing the motion model associated with that line. Experiments on real and synthetic sequences were also presented.     

Filling the gap between voters and cryptography in e-voting

Cryptography is an important tool in the design and implementation of e-voting schemes since it can provide verifiability, which is not provided in the traditional voting. But in the real life, most voters can neither understand the profound theory of cryptography nor perform the complicated cryptographic computation. An e-voting system is presented in this paper to leverage the use of cryptography. It combines the advantages of voting scheme of Moran-Naor and voting scheme based on homomorphic encryption. It makes use of the cryptographic technique, but it hides the details of cryptographic computation from voters. Compared with voting scheme of Moran-Naor, the new system has three advantages: the ballots can be recovered when the voting machine breaks down, the costly cut-and-choose zero-knowledge proofs for shuffling votes made by the voting machine are avoided and the partial tally result in each voting machine can be kept secret. Foundation item: the National Natural Science Foundation of China (No. 60673076) and the National High Technology Research and Development Program (863) of China (No. 2008AA01Z403)     

Batch RSA signature scheme

We describe a batch RSA digital signature scheme in which a signer can sign messages for multiple recipients simultaneously. The construction is quite efficient due to the batch signing method. This is useful to improve the performance of a high-loaded signing server, for example a secure electronic transaction (SET) gateway. Theoretical calculations and experimental results show that the proposed scheme can improve the performance of the signing server significantly. Foundation item: the National Basic Research Program (973) of China (No. 2005CB321804)     

A simulation study of service differentiation for the bandwidth request scheme in fixed IEEE 802.16 network

Various flexible mechanisms related to quality of service (QoS) provisioning have been specified for uplink traffic at the medium access control (MAC) layer in the IEEE 802.16 standards. Among the mechanisms, contention based bandwidth request scheme can be used to indicate bandwidth demands to the base station for the non-real-time polling and best-effort services. These two services are used for most applications with unknown traffic characteristics. Due to the diverse QoS requirements of those applications, service differentiation (SD) is anticipated over the contention based bandwidth request scheme. In this paper we investigate the SD with the bandwidth request scheme by means of assigning different channel access parameters and bandwidth allocation priorities at different packets arrival probability. The effectiveness of the differentiation schemes is evaluated by simulations. It is observed that the initial backoff window can be efficient in SD, and if combined with the bandwidth allocation priority, the SD performances will be better. Foundation item: the National Basic Research Program (973) of China (No. 2005C13321804)     

An authenticated group key distribution scheme for wireless sensor networks

In wireless sensor networks (WSNs), group key distribution is the core of secure communications since sensor nodes usually form groups and cooperate with each other in sensing data collection and in-network processing. In this paper, we present a scalable authenticated scheme for group key distribution based on a combinatorial exclusion basis system (EBS) for efficiency and one-way hash chains for authentication. The proposed scheme guarantees a lightweight authenticated group key updating procedure and is efficient in terms of storage, communication and computation overheads. Foundation item: the National High Technology Research and Development Program (863) of China (Nos. 2006AA01Z436, 2007AA01Z455, and 2007AA01Z473).     

Model-based gait representation via spatial point reconstruction

This paper proposed a novel model-based feature representation method to characterize human walking properties for individual recognition by gait. First, a new spatial point reconstruction approach is proposed to recover the coordinates of 3D points from 2D images by the related coordinate conversion factor (CCF). The images are captured by a monocular camera. Second, the human body is represented by a connected three-stick model. Then the parameters of the body model are recovered by the method of projective geometry using the related CCF. Finally, the gait feature composed of those parameters is defined, and it is proved by experiments that those features can partially avoid the influence of viewing angles between the optical axis of the camera and walking direction of the subject. Foundation item: the National Natural Science Foundation of China (No. 60675024)     

Code-aided interference suppression in direct sequence spread spectrum systems with eigenvector sign spreading code

For direct sequence spread spectrum (DSSS) communication systems suffering interference, it is known that code-aided interference suppression technique outperforms all of the previous linear or nonlinear methods. In this paper, we proposed an improved code-aided technique which can improve the system performance greatly by using the eigenvector sign (EVS) spreading sequence which depends on the statistical characteristics of the interference and the thermal noise. Foundation item: the National Natural Science Foundation of China (No. 60772100)     

A method to improve first order approximation of smoothed particle hydrodynamics

Smoothed particle hydrodynamics (SPH) is a useful meshless method. The first and second orders are the most popular derivatives of the field function in the mechanical governing equations. New methods were proposed to improve accuracy of SPH approximation by the lemma proved. The lemma describes the relationship of functions and their SPH approximation. Finally, the error comparison of SPH method with or without our improvement was carried out. Foundation item: The National Natural Science Foundation of China (No. 50778111); The Key Project of Fund of Science and Technology Development of Shanghai (No. 07JC14023)     

光纤网中可变波长光交换机的优化设计

为了解决光波转换器成本昂贵与其在光纤网络中的重要性之间的矛盾，提出了新的可变波长光交换机结构和相应的优化路由及波长分配算法．为了验证该可变波长光交换机的优越性，基于NSF网络进行了仿真，并给出了最有效的光波转换器的使用方法及其配置．该光交换机设计结构和仿真工具，可以方便地应用到其它骨干光网络中各个交换节点的最优化设计中．     

The factors analysis and algorithm implementation of single-pattern matching

By studying the algorithms of single pattern matching, five factors that have effect on time complexity of the algorithm are analyzed. The five factors are: sorting the characters of pattern string in an increasing order of using frequency, utilizing already-matched pattern suffix information, utilizing already-matched pattern prefix information, utilizing the position factor which is absorbed from quick search algorithm, and utilizing the continue-skip idea which is originally proposed by this paper. Combining all the five factors, a new single pattern matching algorithm is implemented. It’s proven by the experiment that the efficiency of new algorithm is the best of all algorithms. Foundation item: the National Natural Science Foundation of China (Nos. 60502032 and 60672068)     

Surface reconstruction of scanned human body using radial basis functions and adaptive partition of unity

It is important to reconstruct a continuous surface representation of the point cloud scanned from a human body. In this paper a new implicit surface method is proposed to reconstruct the human body surface from the points based on the combination of radial basis functions (RBFs) and adaptive partition of unity (PoU). The whole 3D domain of the scanned human body is firstly subdivided into a set of overlapping subdomains based on the improved octrees. The smooth local surfaces are then computed in the subdomains based on RBFs. And finally the global human body surface is reconstructed by blending the local surfaces with the adaptive PoU functions. This method is robust for the surface reconstruction of the scanned human body even with large or non-uniform point cloud which has a sharp density variation. Foundation item: the National Natural Science Foundation of China (No. 50575139) and the Shanghai Special Fund of Informatization (No. 088)     

Synchronization research of a modified time-delayed multi-agent network model

The synchronization of time-delayed multi-agent networks with connected and directed topology is studied. Based on the correlative work about the agent synchronization, a modified model is presented, in which each communication receiver is distributed a delay τ. In addition, a proportional term k is introduced to modulate the delay range and to guarantee the synchronization of each agent. Two new parameters mentioned above are only correlative to the network topology, and a theorem about their connections is derived by both frequency domain method and geometric method. Finally, the theoretical result is illustrated by numerical simulations. Foundation item: the National Natural Science Foundation of China (No. 70571017) and the Research Foundation from Provincial Education Department of Zhejiang of China (No. 20070928)     

A two-step outlier removal procedure for surface reconstruction

Outliers in point clouds affect the performance of surface reconstruction directly. Most of outlier removal methods just remove those outliers far away from the real surface and are only applied to handle watertight surface. In this paper, a two-step outlier removal procedure is proposed to filter the point clouds acquired from the gray code and line-shifting technique. The first step is to remove the outliers far away from the real surface. Some feature points are extracted from the point clouds to construct an initial surface. The points with distances to the initial surface greater than a given threshold are removed as distant outliers. The retained points are linked into lines in each structured light sheet using their Voronoi diagrams. Some of lines which are very close to the real surface are removed as near outliers in the second step. The experimental results show that the proposed method is very effective in removing outliers for surface reconstruction. Foundation item: the National Natural Science Foundation of China (No. 30470488)     

Joint distortion model for progressive image transmission using error correcting arithmetic codes

A novel joint source channel distortion model was proposed, which can essentially estimate the average distortion in progressive image transmission. To improve the precision of the model, the redundancy generated by a forbidden symbol in the arithmetic codes is used to distinguish the quantization distortion and the channel distortion, all the coefficients from the first error one to the end of the sequence are set to be a value within the variance range of the coefficients instead of zero, then the error propagation coming from the entropy coding can be essentially estimated, which is disregarded in the most conventional joint source channel coding （JSCC） systems. The precision of the model in terms of average peak-signal-to-noise has been improved about 0.5 dB compared to classical works. An efficient unequal error protection system based on the model is developed, and can be used in the wireless communication systems.     

Robust stability of neutral systems: A discretized Lyapunov functional method

This paper focuses on the robust stability for time-delay systems of neutral type. A new complete Lyapunov-Krasovskii function (LKF) is developed. Based on this function and discretization, stability conditions in terms of linear matrix inequalities are obtained. A class of time-varying uncertainty of system matrices can be studied by the method. Foundation item: the National High Technology Research and Development Program (863) of China (No. 2006AA05Z148)     

我国高速客运专线的调度指挥模式

分析了影响我国客运专线调度指挥模式选择的因素并结合我国的国情和路情提出我国高速客运专线可能采用的3种调度指挥模式：全路集中调度指挥模式以及区域集中和按通道调度的二级调度指挥模式．确定了我国高速客运专线的调度指挥模式．为适应我国近期高速客运专线的发展与运营需求，我国高速客运专线的调度指挥模式为设置在相关铁路局调度中心的客运专线与既有线调度指挥人员协同办公的区域集中二级调度指挥模式．     

The settlement characteristic of underground urban complex in Shanghai

The effects of excavation unloading, construction reloading and underground water on basal heave of excavation projects were presented and analyzed based on the measurement results of an underground urban complex which was located in Shanghai. The effects on water pressure and building settlements were analyzed as well. The numerical analyses by finite element method (FEM) were conducted. It showed that the soil under the excavation base continued to heave during the following certain construction stage. It also found that the bearing capacity of uplift piles which supported the buildings affected the structure quality significantly. The conclusions can be applied in future projects. Foundation item: the National Natural Science Foundation of China (No. 50679041)     

A new plan and coordination strategy for robot system based on state space

This paper proposes a general plan and coordination strategy for robot system. The state space for robot system is constructed according to the task requirement and system characteristic. Reachable state of the system is figured out by the system’s internal and external constraints. Task plan and coordination are then transformed as trajectory solving problem in the state space, by which the realizable conditions for the given task are discussed. If the task is realizable, the optimal strategy for task execution could be investigated and obtained in state space. Otherwise, it could be transformed to be realizable via adjusting the system configuration and/or task constraint, and the transformation condition could also be determined. This contributes to design, plan, and coordination of the robotic tasks. Experiments of the manipulator path planning and multi-robot formation movement are conducted to show the validity and generalization of the proposed method. Foundation item: the National Natural Science Foundation of China (No. 60675041) and the Program for New Century Excellent Talents in University (No. NCET-06-0398)     

Effect of LaNiO3 interlayer on the dielectric properties of Ba0.5Sr0.5TiO3 thin film on Si substrate

In this study, (100)-oriented growth of Ba_0.5Sr_0.5TiO₃ (BST) /LaNiO₃ (LNO) stacks was obtained on Pt(111)/SiO₂/Si substrates by r.f. magnetron sputtering. The orientation of the subsequently deposited Ba_0.5Sr_0.5TiO₃ thin film was strongly affected by the LNO under layer, and the BST thin film deposited on the (100)LNO-coated Si substrate was also found to have a significant (100)-oriented texture. Effects of LNO interlayer on the dielectric properties of BST thin films were investigated. As a result, the tunability of BST thin film was greatly improved with the insertion of (100)-oriented LNO under layer with proper thickness. Foundation item: the National Key Lab of Nano/Micro Fabrication Technology (No. 9140C 790310060C79) and the National Natural Science Foundation of China (No. 60701012)