STUDY ON PHASE PERCEPTION IN SPEECH

The perceptual effect of the phase information in speech has been studied by auditorysubjective tests. On the condition that the phase spectrum in speech is changed while amplitudespectrum is unchanged, the tests show that: (1) If the envelop of the reconstructed speech signalis unchanged, there is indistinctive auditory perception between the original speech and thereconstructed speech; (2) The auditory perception effect of the reconstructed speech mainly lieson the amplitude of the derivative of the additive phase; (3) td is the maximum relative time shiftbetween different frequency components of the reconstructed speech signal. The speech qualityis excellent while td ＜10ms; good while 10ms＜ td ＜20ms; common while 20ms＜ td ＜35ms, andpoor while td ＞35ms.

A SCHEME OF M-ARY MULTI-CARRIER SPREAD SPECTRUM BASED ON WAVELET PACKET

A novel scheme of M-ary multi-carrier spread spectrum based on wavelet packet is proposed. Its performance is investigated for a multipath, slow Rayteigh fading channel. The performance advantages of the system over that based on DFT are demonstrated by both analytical and simulation methods.

Exact analysis of the azimuth resolution characters of squint SAR

Based on the motion of platform and the scanning rules of the squint SAR, this paper constructs an exact slant range model between a point target and APC, then presents a novel analysis method of the high resolution characters in azimuth of squint SAR. By deeply researching the length of synthetic aperture and the azimuth resolution, we give the application conditions of various formulae about the two important parameters, which is vital to the exact imaging and brief but reasonable processing.

Kernel method-based fuzzy clustering algorithm

The fuzzy C-means clustering algorithm(FCM) to the fuzzy kernel C-means clustering algorithm(FKCM) to effectively perform cluster analysis on the diversiform structures are extended, such as non-hyperspherical data, data with noise, data with mixture of heterogeneous cluster prototypes, asymmetric data, etc. Based on the Mercer kernel, FKCM clustering algorithm is derived from FCM algorithm united with kernel method. The results of experiments with the synthetic and real data show that the FKCM clustering algorithm is universality and can effectively unsupervised analyze datasets with variform structures in contrast to FCM algorithm. It is can be imagined that kernel-based clustering algorithm is one of important research direction of fuzzy clustering analysis.

Classical Completely Integrable System Generated through Nonlinearization of an Eigenvalue Problem

Under the Bargmann constrained condition, the spatial part of a new Lax pair of the higher order MkdV equation is nonlinearized to be a completely integrable system (R2N,dp^dq, H0=1/2F0)(F0= (^q,p) + (^p,p) + (p,q)2). While the nonlinearization of the time part leads to its N-involutive system (Fm).

Cryptanalysis of the One-Time Proxy Signature Scheme Used in Mobile Agents

We ayptanalyze Kim et. al's one-time proxy signature scheme used in mobileagents, and then a successful forgery is introduced It is showed that a dishonest customer cansuccessfully forge a valid one-time proxy signature by impersonating the stiver Furthermore, he canrequest the server with responsibility for the forged bidding information.

OPTIMAL DESIGN OF SMART ANTENNA ARRAY

This letter investigates an efficient design procedure integrating the Genetic Algorithm (GA) with the Finite Difference Time Domain (FDTD) for the fast optimal design of Smart Antenna Arrays (SAA). The FDTD is used to analyze SAA with mutual coupling. Then,on the basis of the Maximal Signal to Noise Ratio (MSNR) criteria, the GA is applied to the optimization of weighting elements and structure of SAA. Finally, the effectiveness of the analysis is evaluated by experimental antenna arrays.

A Secure and Efficient (t, n) Multi-Secret Sharing Scheme

Based on Shamir's secret sharing, a (t, n) multi-secret sharing scheme isproposed in this paper p secrets can be shared among n participants, and t or more participants canco-operate to reconstruct these secrets at the same time, but t— 1 or fewerparticipants can derivenothing about these secrets. Each participant's secret shadow is as short as each secret. Comparedwith the existing schemes, the proposed scheme is characterized by the lower complexity of thesecret reconstruction and less public information. The security of this scheme is the same as thatof Shamir' a threshold scheme. Analyses show that this scheme is an efficient, computationallysecure scheme.

A DELAY BASED BACKOFF SCHEME FOR WLAN WITH QoS GUARANTEE AND ITS PERFORMANCE

Based on the Distributed Coordination Function (DCF) and the Enhanced DCF (EDCF) mechanisms in IEEE 802.11 and 802.11e, a novel backoff scheme for Wireless Local Area Network (WLAN) is proposed. The scheme is to solve the problem of the packet loss and the decrease of performance due to the increasing Contention Window (CW) when there are continuous collisions. In the proposed scheme, the CW of the packet will change dynamically with different delay for the different traffics. Mathematic formulas are presented to indicate the relationship between the CW and the delay character. ,The performance of the new scheme is also discussed with simulation results. The results show that it helps WLAN system handle multimedia simultaneously.

JOINTLY ESTIMATING BOTH RANGE AND DOA OF NEAR FIELD SOURCE

A computationally efficient method for jointly estimating both Directions Of Arrival (DOA) and ranges of near field sources is presented. The proposed algorithm does not need any spectral peak searching and the 2-D parameters are automatically paired. It is suitable for arbitrary additive Gaussian noise environment. Furthermore, its performances are confirmed by computer simulations.

ON THE SCATTERING OF ARBITRARY SHAPE MICROSTRIP PATCH

In this letter, discrete complex image method is employed to compute the Green's functions in the spatial domain, which improves the speed of evaluating the impedance matrix.The triangle vector basis function--RWG, is used to simulate the current distribution in order to compute the scattering properties of arbitrary shape microstrip patch without the staircase approximation. The numerical result shows the validity of the proposed method.

EVALUATION OF POWER SPECTRAL DENSITY OF PASSIVE INTERMODULATION DISTORTION IN HIGH-POWER COMMUNICATION SATELLITE SYSTEMS

In order to analyze the deleterious effects of Passive InterModulation (PIM) on high power communication satellite systems, the basic concept of PIM is introduced, and an equation for the power spectral density of the n-th order PIM distortion insuch systems is derived by applying flat signal-power spectrum assumption and Fourier transform method. It is indicated that PIM level generally decreases with order and the lowest frequency receive channel in the receive band is the channel of most affected by PIM interference.

A NOVEL DIRECTION OF ARRIVAL ESTIMATOR

A Direction Of Arrival(DOA) estimator based on the signal separation principle is introduced, and one of representative multidimensional estimators is established by introducing Matrix Operator projection signal steering Vector Excision(MOVE) operation. Thanks to Alternating Separation (AS) technique, the multidimensional problem is transformed into a series of one-dimensional optimal ones. Furthermore, an equivalent simplified implementation of the AS is obtained. Finally the definiteness and uniqueness of the estimator are analyzed.

MULTI-WATERMARKING SCHEME FOR GROUP USERS BASED ON VISUAL CRYPTOGRAPHY

All watermarks are shared into shadow images using VCS(Visual Cryptography Scheme). Only one specific shadow (as a new watermark) is embedded into the host signal and the other ones are distributed to every user in each group as a key. In the watermarking extraction procedure, users in different group can obtain different watermark by combining their shadows with the extracted one from the watermarked signal. Analysis and experimental results show that the new watermarking method is novel, secure and robust.

A Single Channel Measurement System For Brain MIT

A single channel measurement system for brain MIT has been built. The system is composed of an exciting source unit,a detecting unit,a rotating and controlling unit,and imaging unit. The experiment results of single channel measurements show that the system output versus the conductivity of the objects was an approximate linear relationship when the diameter of an object was about 9cm and its conductivity was in 0.1 S/m,0.7 S/m,2 S/m,6 S/m. The sensitivit yof the phase detector was 53 mV/degree from -10 to +10 degree.

Multiuser detector based on wavelet networks

Multiple access interference (MAI) and near-far problem are two major obstacles in DS-CDMA systems. Combining wavelet neural networks and two matched filters, the novel multiuser detector, which is based on multiple variable function estimation wavelet networks over single path asynchronous channel and space-time channel respectively is presented. Excellent localization characteristics of wavelet functions in both time and frequency domains allowed hierarchical multiple resolution learning of input-output data mapping. The ma thematic frame of the neural networks and error back ward propagation algorithm are introduced. The complexity of the multiuser detector only depends on that of wavelet networks. With numerical simulations and performance analysis, it indicates that the multiuser detector has excellent performance in eliminating MAI and near-far resistance.