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 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.     

Wavelength reservation scheme with switch fabric status in distributed mesh optical networks

A new wavelength reservation scheme is proposed to mitigate the connection setup time and minimize the reconfiguration times of optical cross-connects (OXCs) for WDM optical networks in this study. In this scheme, we consider the reconfiguration information of switch fabrics in the signaling protocol, which is designated as the signaling with switch fabric status (SWFS). Distributed reservation algorithms will reserve the wavelength with minimum of reconfiguration times of OXCs along the route. Simulation results indicate that the proposed schemes with switch fabrics status have shorter setup time, lower switching ratio as well as better blocking performance than those of the traditional classic schemes. Moreover, the proposed schemes with SWFS significantly reduce the number of switch fabrics that need to be reconfigured. Foundation item: the National Natural Science Foundation of China (Nos. 60632010 and 60572029) and the National High Technology Research and Development Program (863) of China (No. 2006AA01Z251)     

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).     

Bias current influence on the characteristic of the magnetic-controlled switcher type fault current limiter

A novel magnetic-controlled switcher type fault current limiter (FCL) for high voltage electric network is presented. The current limiting principle of the FCL and the bias current influence on the characteristic of the FCL are discussed. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively. Under the normal state, the bias current adjustment can change the FCL voltage loss; under the fault state, the steady fault current can be easily adjusted to the preset level by bias current regulating. The experimental result is in accordance with the principle analysis and the FCL has the advantages of flexible control strategy and simple and reliable structure. Foundation item: the National Basic Research Program (973) of China (No. 2005CB221505) and the Research Fund for Doctoral Program of High Education of China (No. 20050248058)     

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)     

基于关联环签名的抗第三方欺诈安全电子投票方案

为解决电子投票中存在选票碰撞、第三方机构欺诈选民、需借助匿名通信信道发送选票和投票效率低等问题,结合电子投票的基本原理,采用关联环签名技术实现匿名注册,利用盲签名盲化选票和引入身份序列码保证选票唯一性的方法,设计了一个抗第三方欺诈的安全电子投票方案.该方案不仅实现了投票协议应具备的基本安全要求,并且具有抗选票碰撞、可在任意阶段弃权、不依赖于任何可信第三方和匿名通信信道的功能,同时能够高效实现.实验对比表明,本文方案投票时间复杂度仅为961个模乘运算,且与投票者规模无关,较同等安全性下的现有方案效率至少提高42.9%,适合于大群体选举.      

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)     

基于可信密码模块的远程证明协议

可信密码模块是以我国研发的密码算法为基础,结合国内安全需求与产业市场,借鉴国际先进的可信计算技术框架与技术理念自主创新研发的.本文中首先对可信计算平台密码技术方案和国际可信计算组织规范在密码算法、授权协议和密钥管理等几方面进行了比较.基于可信密码模块,提出的基于隐藏属性证书的远程证明方案,用属性证书代替平台配置信息,不仅能有效防止隐私性的暴露,而且可以在系统升级和备份过程中完成可信检测,提高了实现的效率.     

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)     

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)     

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)     

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)     

How to Play E-Lottery Games via Voting

Introduction Lotteryisapopulargameintherealworld.Howtoplayalotteryincyberspacehasreceived muchattention.E-lotteryisconvenientsinceplay-erscanpurchasethetickets,andobservethegen-erationoftheluckynumberovertheInternet.Manymethodstoprovidee-lotteryservicehave beenproposedintheliteratureinRefs.[1-6].The mainideaistousedelayingfunctionorweaklyse-cretbitcommitment(WSBC)tokeepthewinning numbersecretbeforethescheduledclosingtime.Inmoste-lotteryschemesaplayerpresentsaseed numberinhisticket.Thelucky…     

Study on rotational stabilization in a laser tracking system

The high rolling speed of a missile heavily affects the stabilizing capability of the inertial platform in the laser tracking system (LTS) of the missile. In this paper, a rotational stabilizing platform (RSP) and a fuzzy-PID controller is designed to stabilize the inertial platform. This controller integrates the advantages of both fuzzy controller and classic PID controller. A comparison study is carried out to illustrate the advantages of the proposed fuzzy-PID controller over the classic PID controller. Numerical results indicate that the fuzzy-PID controller outperforms the classic one in effectively handling nonlinear disturbances and quickly stabilizing the inertial platform at the sudden change of missile rolling speed. Foundation item: the China Aerospace Science and Innovation Foundation (No. 06CASC0407)     

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.     

A bintree energy approach for colour image segmentation using adaptive channel selection

A new hierarchical approach called bintree energy segmentation was presented for color image segmentation. The image features are extracted by adaptive clustering on multi-channel data at each level and used as the criteria to dynamically select the best chromatic channel, where the segmentation is carried out. In this approach, an extended direct energy computation method based on the Chan-Vese model was proposed to segment the selected channel, and the segmentation outputs are then fused with other channels into new images, from which a new channel with better features is selected for the second round segmentation. This procedure is repeated until the preset condition is met. Finally, a binary segmentation tree is formed, in which each leaf represents a class of objects with a distinctive color. To facilitate the data organization, image background is employed in segmentation and channels fusion. The bintree energy segmentation exploits color information involved in all channels data and tries to optimize the global segmentation result by choosing the ＂best＂ channel for segmentation at each level. The experiments show that the method is effective in speed, accuracy and flexibility.     

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)     

The Homomorphic Key Agreement

Introduction As a result of the increased popularity ofgroup-oriented applications and protocols, groupcommunication occurs in many different settings:from network layer to application layer. Regard-less of the underlying environment, it is necessaryto pr…