Fairness of sharing protection for multicast in WDM networks

In this paper, the sharing schemes of multicast in survivable Wavelength-Division Multiplexed （WDM） networks are studied and the concept of Shared Risk Link Group （SRLG） is considered. While the network resources are shared by the backup paths, the sharing way is possible to make the backup paths selfish. This selfishness leads the redundant hops of the backup route and a large number of primary lightpaths to share one backup link. The sharing schemes, especially, the self-sharing and cross-sharing, are investigated to avoid the selfishness when computing the backup light-tree. In order to decrease the selfishness of the backup paths, it is important to make the sharing links fair to be used. There is a trade-off between the self-sharing and cross-sharing, which is adjusted through simulation to adapt the sharing degree of each sharing scheme and save the network resources.     

Efficient and Information-Theoretical Secure Verifiable Secret Sharing over Bilinear Groups

Verifiable secret sharing （VSS） is an impor- tant technique which has been used as a basic tool in dis- tributed cryptosystems, secure multi-party computations, as well as safe guarding some confidential information such as cryptographic keys. By now, some secure and efficient non-interactlve VSS schemes for sharing secrets in a fi- nite field have been available. In this paper, we investi- gate verffiably sharing of a secret that is an element of a bilinear group. We present an efficient and information- theoretical secure VSS scheme for sharing such a secret which may be a private key for a pairing based cryptosys- tern. Our performance and security analysis indicates that the newly proposed scheme is more efficient and practical while enjoys the same level of security compared with sim- ilar protocols available. We also demonstrate two typical applications of our proposed VSS scheme. One is the shar- ing of a secret key of Boneh and Franklin＇s identity-based encryption scheme, and the other is the sharing or the dis- tributed generation of a secret key of the leakage resilient bilinear EIGamal encryption scheme.     

Performance Analysis of Wireless Network with Opportunistic Spectrum Sharing via Cognitive Radio Nodes

Cognitive radio (CR) is found to be an emerging key for efficient spectrum utilization. In this paper, spectrum sharing among service providers with the help of cognitive radio has been investigated. The technique of spectrum sharing among service providers to share the licensed spectrum of licensed service providers in a dynamic manner is considered. The performance of the wireless network with opportunistic spectrum sharing techniques is analyzed. Thus, the spectral utilization and efficiency of sensing is increased, the interference is minimized, and the call blockage is reduced.     

APPLSS:Adaptive Privacy Preserved Location Sharing Scheme Based on Attribute-Based Encryption

Unauthorized access to location information in location-based service is one of the most critical security threats to mobile Internet.In order to solve the problem of quality of location sharing while keeping privacy preserved,adaptive privacy preserved location sharing scheme called APPLSS is proposed,which is based on a new hierarchical ciphertext-policy attribute-based encryption algorithm.In the algorithm,attribute authority sets the attribute vector according to the attribute tags of registration from the location service providers.Then the attribute vector can be adaptively transformed into an access structure to control the encryption and decryption.The APPLSS offers a natural hierarchical mechanism in protecting location information when partially sharing it in mobile networks.It allows service providers access to end user’s sensitive location more flexibly,and satisfies a sufficient-but-no-more strategy.For end-users,the quality of service is obtained while no extra location privacy is leaked.To improve service response performance,outsourced decryption is deployed to avoid the bottlenecks of the service providers and location information providers.The performance analysis and experiments show that APPLSS is an efficient and practical location sharing scheme.     

Authentication Mechanism for Secret Sharing Using Boolean Operation

A lossless image secret sharing using a simple Boolean operation is proposed. The concept of visual cryptography in the secret sharing scheme is used to redesign a lossless secret sharing scheme. To ensure that the reconstructed image is the true secret image, an authentication mechanism is imported into the proposed scheme to verify whether the shadows are authentic before reconstructing the secret image. The proposed scheme delivers much more effective performance than Chen and Wu＇s scheme.     

重离子诱导的电荷共享以及MBU敏感性的温度特性

The temperature dependence of charge sharing in a 130 nm CMOS technology has been investigated over a temperature range of 200 to 420 K.Device simulation results show that the charge sharing collection increases by 66%-325% when the temperature rises.The LETth of a MBU in two SRAM cells and one DICE cell is also quantified.Besides charge sharing, the circuit response＇s temperature dependence also has a significant influence on the LETth.     

A Novel Visual Multi-Secret Sharing Scheme Based on Folding-up Operation

The Visual multi-secret sharing （VMSS） scheme is characterized by encoding several secret images into a set of noise-like shares. Most existing VMSS meth- ods have to distort shares to embed additional secret im- ages. As a result, the quality of the decoded original secret image is degraded. This paper proposes a folding-up op- eration based VMSS scheme, which is able to encode one secret image and a group of tag images into shares. The secret image is revealed by stacking all shares, and fold- ing up each chosen share discloses the tag image. The proposed scheme encodes tag images without affecting the quality of the reconstructed secret image. The quality of the decoded secret image is equal to that of the conven- tional Visual secret sharing （VSS） scheme. The superiority of the proposed method is experimental verified.     

Information Network Systems and Information Sharing on Administrative Websites

In Japanese "e-government" policy, called "e-Japan", the "administrative document management system" is functioning as information searching systems. On the other hand, this system has also generated the problem that it is not fully functioning as a means for the information sharing in a governmental agency. So, the purpose of this research is to find how the administrative document management system can function as information sharing in administrative organization. For this purpose, this paper considers the current status and some problems firstly. And secondary, this paper proposes the idea and constructs some information systems using administrative official Website. This is the method and approach of this research. As a conclusion, this proposal information system junctions as information sharing support systems.     

Secure Data Sharing and Retrieval Using Attribute-Based Encryption in Cloud-Based OSNs

The Online social networks （OSNs） offer attractive means for social interactions and data sharing, but also raise a number of security and privacy issues. Since the OSNs service provider is always semi-trusted, current solutions propose to encrypt data before sharing. However, data encryption causes a lot of inconveniences and large overheads for data dissemination and data retrieval. In this paper, we propose a secure data sharing and retrieval scheme in cloud-based OSNs. Based on ciphertext-policy attribute-based encryption, our scheme achieves multi- party access control, which allows data owners to outsource encrypted data to the OSNs service provider for sharing, and enables data disseminators to disseminate the data owners＇ data by customizing new access policy. Our scheme also provides searchable encryptlon scheme to support fast searches in massive amount of encrypted data from both data owners and data disseminators. Further, our scheme preserves the privacy of data owners and data retrievers during the data sharing and retrieval processes. In addition, the computation overhead of data retrievers is reduced by delegating most of the decryption operations to the OSNs service provider. The security and performance analysis results indicate that our scheme is secure and privacy-preserving.     

ASYNCHRONOUS BYZANTINE AGREEMENT PROTOCOL BASED ON VERIFIABLE SIGNATURE SHARING

An （[n/3]-1 ）-resilient Asynchronous Byzantine Agreement Protocol （ABAP） that combines verifiable signature sharing and random secret sharing is proposed. The protocol works in the asynchronous network environment and produces Byzantine agreement within a fixed expected number of computational rounds. The correctness of the protocol is proved in theory.     

Module sharing design technique for dual reflector antenna

Module sharing technique for a dual reflector antenna is presented, which makes different apertured main reflectors of the same focus sharing one set of module by means of optimizing the subreflector. To optimize the subreflector, a fast convergence optimization method is given with a satisfactory result.     

双反射面天线主面模具共享技术及其优化方法

本文提出了通过优化副反射面使同一焦距不同口径的主反射面共用一套加工模具的双反射面天线主面面板模具共享技术。提出了一种快速收敛优化方法,并将其应用于主面共享设计,取得了较为满意的结果。     

Zooming and Scanning Gregorian Confocal Dual Reflector Antennas

The zooming and scanning capabilities of a Gregorian confocal dual reflector antenna are described. The basic antenna configuration consists of two oppositely facing paraboloidal reflectors sharing a common focal point. A planar feed array is used to illuminate the subreflector allowing the antenna to scan its beam. The resulting quadratic aberrations can be compensated by active mechanical deformation of the subreflector surface, which is based on translation, rotation and focal length adjustment. In order to reduce the complexity of the mechanical deformation, least squares fit paraboloids are defined to approximate the optimal correction surface. These best fit paraboloids considerably reduce scanning losses and pattern degradation. This work also introduces two different zooming techniques for the Gregorian confocal dual reflector antenna: the first consists of introducing a controlled quadratic path error to the main reflector aperture; and the second is based on reducing the size of the radiating aperture of the feeding array.      

The effects of subreflector diffraction on the aperture efficiency of a conventional Cassegrain antenna--An analytical approach

An asymptotic theory is presented with which the reduction in aperture efficiency caused by diffraction from a subreflector edge can be calculated for any dual-reflector system. The theory is applied to conventional Cassegrain antennas, for which approximate analytical effieiency formulas are derived. These formulas show that subreflector diffraction may represent a significant efficiency loss even for subreflector diameters as large as 20 wavelengths. The formulas are used to obtain an optimum subreflector size which represents the best trade-off between losses due to subreflector diffraction and geometrical shadowing.     

La synthèse d’antennes à deux réflecteurs conformés à alimentation décalée

A potentially economic method for upgrading the gain of the large earth reflector antenna Cassegrain system to a gain comparable to that obtainable with a dualshaped reflector antenna system is presented herein. It involves a redesign of only the subreflector portion of a Cassegrain antenna or the introduction of a subreflector feed system for a paraboloid. A pair of offset subreflectors are synthesized which will give a controllable high gain amplitude distribution in the aperture of the large paraboloid. The synthesis method that is used is based on an approximate formulation for an offset dual shaped high gain antenna where the geometrical optics energy was scattered from a subreflector and then from a second large reflector which reflected a uniform phase distribution. In the present offset dual shaped subreflector (DSS) antenna, the second reflection is from a smaller subreflector and it scatters a spherical wave that feeds a hyperboloid or feeds a large paraboloid directly. Excellent results are shown for the approximate synthesis of the DSS.     

Subreflector shaping for antenna distortion compensation: an efficient Fourier-Jacobi expansion with GO/PO analysis

Technological demands have brought a renewed interest in the application of large reflector antennas with steadily increasing operating frequencies and antenna dimensions. The high surface accuracy of the main reflector required by these antennas can often not be achieved with available manufacturing technologies. The utilization of a shaped subreflector for main reflector-distortion compensation is considered an effective measure to enhance the overall radiation performance of an antenna system. In the process of evaluating the suitability of the subreflector shaping, however, it is crucial to accurately assess the most suitable subreflector shape within a reasonable amount of computational time. This is especially true for electrically large reflectors, where simple analysis of the radiation characteristics already creates a serious computational burden, moreover, since reflector shaping is a synthesis process that necessitates repeated computation of the radiation characteristics. In this paper, the development of an efficient computational tool for subreflector shaping is presented. The subreflector shaping is performed through a combination of geometrical optics (GO) and physical optics (PO) on the subreflector and the main reflector, respectively. To significantly limit the number of parameters subject to optimization, the subreflector surface is parameterized by the coefficients of a global, orthogonal Fourier-Jacobi set (related to Zernike polynomials), which allows us to accurately represent a surface with only a small number of coefficients. The incorporation of this surface expansion into a GO/PO synthesis technique is detailed, representative results are given for a computationally challenging reflector configuration, and the tolerances for the shaped subreflector surface are studied.     

Design of a dichroic Cassegrain subreflector

The design of a dichroic subreflector for a dual-frequency reflector antenna is described. This antenna consists of aKu-band Cassegrain feed requiring the subreflector surface to be highly reflective at 13-15 GHz and a primary focusS-band feed requiring the subreflector to be transparent at 2.0-2.3 GHz. Such a performance is achieved by a surface of crossed dipoles printed on a dielectric sheet. The influence of parameters, dipole length, width and spacing, and the dielectric constant and thickness of the sheet on the reflection and transmission coefficients is experimentally evaluated. An analysis based upon the Floquent mode theory is shown to correctly predict the experimental results. The construction of a hyperbolic subreflector using the selected surface parameters is briefly described. As compared to a solid subreflector of identical shape, this dichroic subreflector produced a negligible loss (less than 0.1 dB) over a 13-15 GHz band. At theSband the loss was less than 0.2 dB over narrow selected bands and the axial ratio deterioration was also no more than 0.2 dB.     

Feed-reflector design for large adaptive reflector antenna (LAR)

A novel feed-reflector system for large Cassegrain antennas of radio astronomy and deep-space communication applications is investigated. This feed-reflector is used to illuminate a hyperboloid subreflector with a 5-10 m diameter located 500 m above the ground. Because the subreflector is located in the near field of the feed-reflector antenna, a theory based on the near field focusing properties of paraboloid reflectors is established. The focusing at near distance is formed by moving the feed horn away from the focal point of the feed-reflector. In this theory, the properties of axial defocused paraboloid reflectors at near distance are investigated in more detail. By using equivalence path law, the subreflector shape is obtained. It is found that the hyperbola can approximate the subreflector well. A detailed ray tracing is performed on the entire system which reveals that the feed system uses some part of the subreflector three times. The gain, side lobe level, cross polarization, and aperture distribution are calculated for different feed horn locations and taper at the edge of the feed-reflector and also for different sizes and eccentricities of the subreflector. Peak efficiency in excess of 74.8% and side lobe level around -20 dB are obtained for an unshaped system. The performance of the system over the operating band (1-22 GHz) is also studied and shown that the lower-frequency limit is dependent on subreflector and feed-reflector sizes     

High efficiency and low sidelobe design for a large aperture offset reflector antenna

A design method giving high efficiency and low sidelobes is discussed for large aperture offset reflector antennas. A new reflector shaping technique using the subreflector and the beam waveguide reflector with the parabolic main reflector is proposed to simplify the main reflector manufacturing process. The effectiveness of the technique is confirmed by the model experiments. One problem with this reflector shaping technique is that the subreflector edge level cannot be controlled independently of the main reflector edge level. By investigating the relation between the gain reduction and the subreflector edge level, which affects the wide-angle sidelobe levels, the realizable characteristics of antennas are studied. In order to decrease the subreflector edge level without reducing the aperture efficiency, a technique using an extended reflector is also proposed. Its effectiveness is shown by theoretical and experimental investigations.     

Subreflector extension for improved efficiencies in Cassegrain antennas--GTD/PO analysis

Both offset and symmetric Cassegrain reflector antennas are used in satellite and ground communication systems. It is known that the subreflector diffraction can degrade the performance of these reflectors. A geometrical theory of diffraction/physical optics (GTD/PO) analysis technique is used to investigate the improving effects of the extended subreflector, beyond its optical rim, on the reflector efficiency and farfield patterns. Representative numerical results are shown for an offset Cassegrain reflector antenna with different feed illumination tapers and subreflector extensions. It is observed that for subreflector extensions as small as1 lambdanoticeable improvements in the overall efficiencies can be expected. Useful design data are generated for the efficiency curves and far-field patterns.