Journal of University of Chinese Academy of Sciences

Cryptanalysis of a Blind Proxy Signature Scheme

CAO Zheng-Jun, LIU Mu-Lan

2006, 23 (2): 145-148. DOI: 10.7523/j.issn.2095-6134.2006.2.005

The blind proxy signature scheme proposed in [1] is insecure. Managing center C cannot reveal the identity of the actual proxy signer of a given proxy signature. Besides，C and the original signer A can conspire to generate valid proxy signatures and impose them on an arbitrary proxy signer by using the identifying equation.

Method of Artificial Neural Network for Shimming of NMR Magnet

JIAO Wei-Wei, DONG Zeng-Ren, SUN Wei, LIU Wei

2006, 23 (2): 149-154. DOI: 10.7523/j.issn.2095-6134.2006.2.006

Abstract ( 1803 ) PDF (KB) ( 0 )

: Homogeneous magnetic field is necessary in NMR magnet. In general shimming magnetic field is by experience. So it’s difficult to shim. It depends on experiences frequently. Artificial Neural Network based on the ANN toolbox of Matlab is put forward to apply in the process. Error backward propagating network is created. The method is varied from different uniformity of magnetic field. The neural network consists of two subnets—coarse regulating network and fine regulating network which are trained respectively. After the model is established, shimming magnet becomes rapidly and accurately. The ferromagnetic shim needn’t be tried many times and aimlessly. It is judged only once. Magnet shimmed by ANN has a nice uniformity and can meet the condition of NMR core Analyzer well.

Nonlinear Rectification Method of Platinum Resistance by BP Neural Network

DU Fu-Jia, WANG Da-Xing

2006, 23 (2): 155-158. DOI: 10.7523/j.issn.2095-6134.2006.2.007

Abstract ( 1405 ) PDF (KB) ( 0 )

This article uses BP neural network to calibrate nonlinear characteristic of platinum resistance, gives the structure of BP neural network and the method to train weight. The input are normalized when train the network. Finally, this neural network calibrates a fact system. This method can be achieved very easily. Using platinum becomes very convenience in measurement through this method

SAR Image Denosing Based on Wavelet-Domain Gaussian-Cauchy Mixture Model

ZHANG Jun-Bao, SONG Hong-Jun

2006, 23 (2): 159-164. DOI: 10.7523/j.issn.2095-6134.2006.2.008

Abstract ( 1685 ) PDF (KB) ( 0 )

(Symmetric alpha-Stable) model is an accurate image model in Wavelet-domain. But this method needs lots of computation. In this paper, a new model, Gaussian-Cauchy model, was proposed on the base of model. Using this model characterizing the real-world images prior model can reduce computations obviously. In addition, the logarithm transform changes its statistical characteristic, so we must adjust the mean in the process. Experimental results show that there is almost nothing differences between this model and model in edges、 SNR (signal to noise ratio) and subjective visual effect.

A Lossless Information Hiding Method Based on Video

GUO Zhi-Chuan, CHENG Yi-Min, WANG Yi-Xiao, XIE Yu-Ming

2006, 23 (2): 165-173. DOI: 10.7523/j.issn.2095-6134.2006.2.011

Abstract ( 1325 ) PDF (KB) ( 0 )

A lossless information hiding method based on MPEG-2 color video is proposed in this paper. The method is based on Alattar’s algorithm and it reduced type judgement conditions from Alattar’s 4 inequations to 2 inequations, so it reduced time complexity. Simple data link frame is used during data hiding processing and covert communication experiments are simulated in Local networks by using the algorithm. Host video information can be lossless restored after embedded Chinese characters or fingerprinting images are correctly extracted from video which embedded information. The method can be applied to covert communication or copyright protection of video product.

Embedded Speaker-Independent Continuous Speech Recognition System Based on MPC5200

LIU Bin, DU Li-Min

2006, 23 (2): 174-177. DOI: 10.7523/j.issn.2095-6134.2006.2.013

Abstract ( 1368 ) PDF (KB) ( 0 )

The embedded systems’ ability is not enough to run HMM-based speaker-independent continuous speech recognition algorithms, especially the search algorithm and the state likelihood computation. This paper proposes an embedded platform based on MPC5200 microprocessor, and implements a HMM-based speaker-independent continuous speech recognition system on this embedded platform. The experiments show that the real-time performance of this embedded speech recognition system is acceptable.

Building’s Roof Extraction by Fusing High-Resolution SAR with Optical Images

…ZHU Jun-Jie, FAN Xiang-Tao, SHAO Yun

2006, 23 (2): 178-185. DOI: 10.7523/j.issn.2095-6134.2006.2.014

Abstract ( 1644 ) PDF (KB) ( 0 )

The extraction of building’s roof is an important step in 3D reconstruction of building. In order to more precisely extract the roof information, both high-resolution optical and SAR images were fused in this paper. Layerover of building in SAR image was used to determine that building on optical image, and thereafter a small window was setup including building’s roof. The ISODATA classification method was used to obtain an outline of building’s roof for the small window. Finally, the regular outline of the roof was computed. The experiment proved that this method was feasible.

Inflight Measurement of Antenna Pattern for Spaceborne SAR Using Encoding Transmitters

WANG Xiao-Lin, HONG Jun

2006, 23 (2): 186-191. DOI: 10.7523/j.issn.2095-6134.2006.2.016

Abstract ( 1455 ) PDF (KB) ( 0 )

Inflight measurement of antenna pattern is a key technology of spaceborne SAR calibration. This paper describes a new method of antenna receive pattern measurement for spaceborne SAR using encoding transmitters. Considering the characters of SAR system, the principle is described briefly. The orthogonal modulation code is chosen and the arithmetic of signal generating, receiving, decoupling and processing is derived. The results of computer simulation prove that this measurement method is feasible.

Research of MPEG-7 ScalableColor Descriptor

LI Zhi-Quan, LI Jian-Hui, YAN Bao-Ping

2006, 23 (2): 192-197. DOI: 10.7523/j.issn.2095-6134.2006.2.017

Abstract ( 1138 ) PDF (KB) ( 0 )

ScalableColor Descriptor is one of the independent four Color Descriptors among MPEG-7.In this paper, we will introduce particularly the background, Descriptor components semantics, bitplane, Haar transform and matching algorithm in the MPEG-7. This article also accounts for applying scope of the descriptor and this will be helpful to those readers who will use the Descriptor.

Identity-Based Threshold Decryption Schemes Secure against Chosen Ciphertext Attacks in the Standard Model

MEI Qi-Xiang, HE Da-Ke

2006, 23 (2): 198-204. DOI: 10.7523/j.issn.2095-6134.2006.2.020

Abstract ( 1388 ) PDF (KB) ( 0 )

We propose two efficient Identity-Based threshold decryption schemes They are proved secure against chosen ciphertext attacks under the standard decisional bilinear Diffie-Hellman assumption. The first one is constructed from (one of ) the Selective ID-Based Encryption (Selective-IBE) scheme proposed by Boneh and Boyen recently, yet the second one is transformed from the Full ID-Based Encryption (Full-IBE) scheme obtained by Waters. As the based IBE schemes, the attacker in the first proposal has to choose the challenge identity before the common parameter is generated, while the attacker in the second one could choose the identity adaptively. To the best of our knowledge, previous related schemes could only be proved secure in the random oracle model.

An Unified Framework Supporting Multiple Security Policy Models to Secure Linux

YUAN Chun-Yang, SHI Wen-Chang, LIANG Hong-Liang, WU Yan-Jun, SHANG Qing-Hua

2006, 23 (2): 205-212. DOI: 10.7523/j.issn.2095-6134.2006.2.022

Abstract ( 1590 ) PDF (KB) ( 0 )

As the basis of various applications, operating systems cannot avoid more and more security threats. There are two main access control schemes in Linux system, i.e. traditional simple discretionary access control and capabilities. They are not perfect enough to protect system against attacks. From access control and privilege division, security policy models are designed and implemented as loadable kernel modules to secure Linux. Although many security policies have been proposed already until now, different security policies are required for system under different environments. It is necessary for unified framework to combine these various security policies and adjust the priority of policies with different application requirements appropriately. By this way, the adaptivity of system can be improved. SECIMOS (SECurity in Mind Operating System), as an unified framework supporting multiple security policy modules simultaneously, allows to load different modules selectively when trading off between security and performance. This framework is based on LSM (Linux Security Module). However, LSM does not provide policies to determine the call sequence of multiple modules and mechanisms to implement the non-access control modules. In SECIMOS, these problems are solved by assigning metapolicy and extending LSM. In this paper, we analyze the restrictions of two main security schemes in Linux system. Then SECIMOS architecture is outlined; security policy model and security modules are introduced respectively. The way to combine these modules in LSM is described. The performance of SECIMOS and the comparison with other security projects are discussed at last.

Stress Triggering of Static Coulomb Stress of Xinjiang Bachu-Jiashi Earthquake of Ms 6.8, Feb. 24, 2003

WANG Qiong, CHEN Xue-Zhong, WANG Hai-Tao

2006, 23 (2): 213-220. DOI: 10.7523/j.issn.2095-6134.2006.2.024

Abstract ( 1353 ) PDF (KB) ( 0 )

There occurred an of earthquake of Ms 6.8 in Bachu-Jiashi county, Xinjiang , on Feb.24, 2003. There are 7 strong aftershocks greater than Mw 5 till June 30th,2004, and aftershocks of the sequence are rich and stronger. The article calculates the change of static stress of Ms 6.8 mainshock, both mainshock and aftershocks on rupture surface of sequent mid-strong aftershocks. Considering epicenter location error, the article discusses the change of static stress of Ms 6.8 mainshock, both mainshock and mid-strong aftershocks in different aspects, and analyses quantitatively the relation between static stress change of Ms 6.8 sequence and fault type, and delay time and spatial range effected by static triggering model. It is reasonable to employ the focal mechanism solution and depth in Harvard CMT catalogue and Xinjiang results of location epicenter , and 7 mid-strong aftershocks occur all in the increasing There occurred an of earthquake of Ms 6.8 in Bachu-Jiashi county, Xinjiang , on Feb.24, 2003. There are 7 strong aftershocks greater than Mw 5 till June 30th,2004, and aftershocks of the sequence are rich and stronger. The article calculates the change of static stress of Ms 6.8 mainshock, both mainshock and aftershocks on rupture surface of sequent mid-strong aftershocks. Considering epicenter location error, the article discusses the change of static stress of Ms 6.8 mainshock, both mainshock and mid-strong aftershocks in different aspects, and analyses quantitatively the relation between static stress change of Ms 6.8 sequence and fault type, and delay time and spatial range effected by static triggering model. It is reasonable to employ the focal mechanism solution and depth in Harvard CMT catalogue and Xinjiang results of location epicenter , and 7 mid-strong aftershocks occur all in the increasing

A Simulation Study of Tropospheric Ozone over Europe with MOZART-2

LIU Qian-Xia, WANG Bin, ZHANG Mei-Gen

2006, 23 (2): 221-230. DOI: 10.7523/j.issn.2095-6134.2006.2.025

Abstract ( 1359 ) PDF (KB) ( 0 )

An off-line coupling model system consisting of a global three-dimensional atmospheric chemistry transport model MOZART-2 and a global three-dimensional atmospheric circulation model CAM2 is newly set up and applied to simulate tropospheric ozone over Europe. Comparison of model results with multi-year ground level observations over Europe shows that the seasonal variations of surface ozone mixing ratios can be generally reproduced with slight overestimations at Hohenpeissenberg and a little underestimation at Kollumerwaard; in addition, the magnitude and general features of surface CO seasonal variations can also be well captured. Compared with ozonesonde observation data at Lindenberg in Germany and Sodankyla in Fanland, the vertical gradient and magnitude of tropospheric ozone mixing ratios can be well reproduced, especially in autumn when the simulated mid-troposphere ozone levels at above both sites are in better agreement with observations. Compared with ozonesonde observations at Hohenpeissenberg in Germany and Nyalesund in Norway, seasonal cycles of ozone concentrations at 300hPa, 500hPa and 800hPa can also be fairly reproduced, especially at 300hPa. Overall, good simulations of tropospheric ozone concentrations over Europe by using this model system can lay a scientific basis for further study of Tran-Eurasian transport of pollutants.

The Environmental Impact of Residential Building Construction in Beijing : 1949-2003——Assessing the Construction Materials’ Environmental Impact by LCA

LIU Tian-Xing, HU Dan

2006, 23 (2): 231-241. DOI: 10.7523/j.issn.2095-6134.2006.2.028

Abstract ( 1491 ) PDF (KB) ( 0 )

After 1949, especially in recent 20 years, the number of Beijing’s residential building has increased rapidly. Such fast development also poses a great impact on the eco-environment. Generally, the methods of assessing the impact of buildings focus on the direct or local impact during the construction or using period. This article assesses the indirect impact of the building materials in a city’s scale using the Life Cycle Assessment method. According to the analysis result, we find that the increase rate of residential building’s impact is higher than that of building area. After the discussion, we owing this difference to the building structures and building materials.

Baoqing County of Sanjiang Plain Land Use Change TuPu Analysis

KUANG Wen-Hui, ZHANG Shu-Wen, HOU Wei, ZHANG Yang-zhen

2006, 23 (2): 242-250. DOI: 10.7523/j.issn.2095-6134.2006.2.029

Abstract ( 1468 ) PDF (KB) ( 0 )

This paper improves the traditional method of land use dynamic change spatial analysis and analyzes land use TuPu spatial-temporal change based on the Geo-information TuPu theory. With the example of Baoqing county of Sanjiang plain, it analyzes the regional different land use change process and change modes based on expanding, shrinking, disappearing, appearing and resurging from 1954 to 2000 depending on the land use spatial data from 1954,1976,1986 and 2000. In conclusion, the regional cultivated land increases 451197.65hm2 from 1954 to 2000. Wetland reduces 263122.5 hm2 from 1954 to 2000. The cultivated land increase engrosses lots of grassland and wetland; the woodland decreases except from 1954 to 1976;the village and town construction expands. Land use entities expanding and shrinking mainly happen the borderline of the big entity units. The entities of disappearing, appearing and resurging are mainly the small entity units. By analyzing modes of the land use change TuPu, we conclude that man activities reclamation leads to cultivated land increasing and wetland dropping. The regional ecological environment is worsening and biodiversity is decreasing. At the same time, the regional ecological interfaces are changing.

Generating Orthomorphisms Bit by Bit

XU Hai-Bo, LIU Hai-Jiao, JING Ji-Wu, DU Jiao

2006, 23 (2): 251-256. DOI: 10.7523/j.issn.2095-6134.2006.2.032

Abstract ( 1150 ) PDF (KB) ( 0 )

Due to that orthomorphisms have good cryptographic properties, they play an important role in cryptography for resisting cryptanalysis. A new method is presented to construct an (n+1)-bit orthomorphism from an n-bit one where n>1. First, details of the method are provided and discussed. Then a simple example is presented to show how a 2-bit orthomorphism is expanded, rearranged, and selected to form a 3-bit one. Some experimental data are analyzed to demonstrate the efficiency of the construction. The method is not only a new way to construct orthomorphisms but also a new attempt of research in orthomorphism structure for building a relationship between n-bit orthomorphisms and (n+1)-bit ones.

A New Security Analysis for XOR Message Authentication Code

WANG Da-Yin, LIN Dong-Dai, WU Wen-Ling, JIANG Zhong-Hua

2006, 23 (2): 257-262. DOI: 10.7523/j.issn.2095-6134.2006.2.034

Abstract ( 1779 ) PDF (KB) ( 0 )

Message Authentication Codes are very important tools to protect data integrity. XOR-MAC is defined by Bellare, which also give a security analysis for it. But security analysis for XOR-MAC they gave is complex. In this paper, we use Game-Playing technique to give a new security analysis for XOR-MAC. We prove XOR-MAC secure, quantifying an adversary’s success probability of distinguishing XOR-MAC from purely random function in terms of the quality of the block cipher as a pseudorandom permutation.

Azimuth Compression of Space-Borne SAR Based on FPGAs

ZHENG Xiao-Shuang, YU Wei-Dong

2006, 23 (2): 263-269. DOI: 10.7523/j.issn.2095-6134.2006.2.036

Abstract ( 2163 ) PDF (KB) ( 0 )

Real-time Imager is essential for intending space-borne Synthetic Aperture Radar (SAR). A space-borne SAR with a real-time imager integrated in it has augmented performance and broadened applications. Azimuth compression is a key in real-time imaging. This paper explains the rationale of azimuth compression of SAR and analyzes the parameters of the real-time imager in detail, then puts forward a method of azimuth compression based on FPGAs, which is used in real-time imager in space-borne SAR. Such a processor for azimuth compression concerns ISA interface, FFT operating, match filtering and absolute value computing. Considering the special demands of devices used in space environment, Xilinx VirtexII FPGAs are selected as main devices for this design. The simulation of point target and result of raw data imaging demonstrate that this method meets the requirements of real time processing in space-borne SAR.

Syntheses, Structural Characterizations and Properties of Some Novel polyoxomolybdates Linked by Coordinated Transition Metal or Lanthanide Cations

WU Chuan-De, LU Can-Zhong

2006, 23 (2): 270-276. DOI: 10.7523/j.issn.2095-6134.2006.2.037

Abstract ( 1272 ) PDF (KB) ( 0 )

A series of novel double helicates, {A[Mo2VIO4LnIII(H2O)6(C4H2O6)2]·4H2O}n (Ln = Sm, Eu, Gd, Ho, Yb, Y; C4H2O6 = L-tartaric acid； A = NH4 or H3O), have been synthesized from the reactions of chiral ligands L-tartaric acid with molybdates as well as lanthanide cations. The architectures of these compounds are one dimensional enantiopure novel right- or left-handed double helical one-dimensional chains, which are somehow like DNA in general configurations. By the hydrothermal reaction method, some molybdenum oxide units such as {MoO4}, {Mo2O7}, {Mo8O26} are linked up by transition metal/organic ligand fragments to novel zero-, one-, two- or three-dimensional structures. Most of these compounds have voids, which are occupied by some suitable crystallization molecules. These compounds are: [Cu(4,4’-bpy)]2MoO4·2H2O, [Cu(4,4’-bpy)]2Mo2O7 and [Cu(4,4’-bpy)(Hnic)(H2O)]2Mo8O26. Compound [Gd(H2O)3]3[GdMo12O42]·3H2O is the first product in the herterometallate chemistry containing lanthanide cations that is synthesized by the hydrothermal reaction. The compound is built up by Silverton-type [GdMo12O42]9- anions linking up nine coordinated Gd3+ cations. It is the first example for introducing a paramagnetic lanthanide cation into the Silverton-type anionic center, which provides a very interesting example for the further synthesis of such kind compound/polymer. One-dimensional polymer, [Cu2(C8H6N2)2(C7H6N2)]2[Mo8O26], which consists of β-[Mo8O26]4- anions linked by quinoxaline and its oxidized product benzimidazole ligands coordinating binuclear copper(I) fragments, provides the first example that the isolated copper(I) complex under hydrothermal conditions “captures” the reduction product of original starting organonitrogen ligand to form a copper(I)-β-octamolybdate complex.

Studies on Inverse Opal and Two-Dimensional Nonlinear Photonic Crystals

NI Pei-Gen, CHENG Bing-Ying, ZHANG Dao-Zhong

2006, 23 (2): 277-287. DOI: 10.7523/j.issn.2095-6134.2006.2.038

Abstract ( 1187 ) PDF (KB) ( 0 )

In this paper, we report some results on inverse opal photonic crystal and two-dimensional periodically poled lithium niobate photonic crystal. At first the process of infiltrating TiO2 into SiO2 Opal was systematically studied. Because of the infiltration of TiO2 the gap of SiO2 Opal was shifted to longer wavelength and a maximum shift of 62 nm was observed. Furthermore, an inverse TiO2 Opal with larger filling fraction, ~ 12%, was fabricated, whose band gap in the G-L direction located in the ultraviolet region (~380 nm). Then two-dimensional nonlinear photonic crystals of lithium niobate with uniform square lattices were fabricated by applying external electric field. The variations of second-harmonic output with crystal temperature, incident angle and reversed duty cycle were measured. Red, yellow, green, blue, and violet coherent radiations were generated in the nonlinear photonic crystal with rectangular lattice in the collinearly and non-collinearly quasi-phase matching geometries. The results showed that two-dimensional nonlinear photonic crystal could be used to generate various colors simultaneously and efficiently along different directions.

Current Issue