Xiaopeng Yan

A Secure Biometrics-based Authentication Scheme for Telecare Medicine Information Systems

The telecare medicine information system (TMIS) allows patients and doctors to access medical services or medical information at remote sites. Therefore, it could bring us very big convenient. To safeguard patients’ privacy, authentication schemes for the TMIS attracted wide attention. Recently, Tan proposed an efficient biometrics-based authentication scheme for the TMIS and claimed their scheme could withstand various attacks. However, in this paper, we point out that Tan’s scheme is vulnerable to the Denial-of-Service attack. To enhance security, we also propose an improved scheme based on Tan’s work. Security and performance analysis shows our scheme not only could overcome weakness in Tan’s scheme but also has better performance.

A Chaotic Map-based Authentication Scheme for Telecare Medicine Information Systems

With the development of Internet, patients could enjoy health-care delivery services through telecare medicine information systems (TMIS) in their home. To control the access to remote medical servers’ resources, many authentication schemes using smart cards have been proposed. However, the performance of these schemes is not satisfactory since modular exponential operations are used in these schemes. In the paper, we propose a chaotic map-based authentication scheme for telecare medicine information systems. The security and performance analysis shows our scheme is more suitable for TMIS.

On the security of a dynamic identity‐based remote user authentication scheme with verifiable password update

Summary Recently, Chang et al. [Chang Y, Tai W, Chang H. Untraceable dynamic identity-based remote user authentication scheme with verifiable password update. International Journal of Communication Systems 2013; doi:10.1002/dac.2552] proposed a dynamic identity-based remote user authentication scheme with verifiable password update. They also proved that their scheme could withstand various attacks. Unfortunately, by proposing concrete attacks, we show that their scheme is vulnerable to three kinds of attacks. We also point out that their scheme cannot provide untraceability. The analysis shows that the scheme of Chang et al. is not suitable for practical applications. Copyright

Image Speckle Reduction and Coherence Enhancement in Underwater Ultrasonic Imaging Based on Wavelet Transform

In order to reduce the underwater ultrasonic image speckles and to enhance the image characteristics, an anisotropic diffusion model is established based on the wavelet transform in this paper. At the same time, it also provides the steps of the algorithmic architecture and analyzes the key links of the model during its application. Two-check experiments have been done using simulation data and real underwater ultrasonic image respectively. In experiment a compare research for underwater ultrasonic image has been done using the method and other traditional methods. After performing the WLAD-model-based image speckle reduction and coherence enhancement to the underwater ultrasonic image, we find that this algorithm has the ability to remove the image speckles and enhance the edges. This algorithm can well be applied to removing the speckles and enhancing the edges in the underwater ultrasonic image.

A local normalized method to eliminate riding waves appearing in the empirical AM/FM decomposition

The intrinsic mode function (IMF) generated by empirical mode decomposition (EMD) is usually seen as an amplitude and frequency modulation (AM-FM) signal. To obtain the FM part of an IMF, an empirical AM/FM decomposition method has been proposed by Huang and his coworkers. However, riding waves may appear in the empirical decomposition, which makes the instantaneous frequency (IF) physically meaningless. To eliminate the riding waves, riding wave turnover-empirical AM/FM decomposition method has recently been developed by Yang et al. In this paper, a local normalized method is proposed to eliminate the riding waves. Different from the previous method by Yang et al., the proposed method does not need any more empirical AM/FM decomposition and is carried out locally, which can significantly reduce computational complexity.

Metal Equivalent Measurement Based on Low-Frequency Electromagnetic Induction Method

In order to evaluate the detectability of landmine, a new method based on results of metal equivalent measurement is developed. A series of studies are carried out to evaluate the detectability of landmine academically and experimentally, from the aspect of the relation between detection method and induced signal, the impact of metal mass to induced signal, and landmine metal mass equivalent detection method. In addition, by analyzing the relationship between second field signal and metal mass using the principle of low-frequency electromagnetics, it is verified that in the same detection height and the same medium, mine detectors answer output is directly proportional to the quality of metal. Thus a fitting formula of induction signal and detection height, metal mass is concluded. Experimental results prove that using the method of metal equivalent measurement to evaluate detectability of landmine is effective.

A speckle reduction and image enhancement anisotropic diffusion method for underwater ultrasonic imaging based on wavelet technology

Ultrasonic inherent characteristic and underwater environment make underwater ultrasonic image have speckle noise, and image contrast is low. So need a method to reduce speckle noise and enhance image contrast at the same time. In certain applications, however, the removal of speckle and image enhancement may be two contradictory problem each other, so we difficult to gain an ideal image processing result. For this reason, considerations in characteristic of the underwater ultrasonic image, this paper provides a new speckle reduction and image enhancement anisotropic diffusion method based on wavelet technology. An anisotropic diffusion model has been established based on wavelet transform. We analyze the characteristic of the model and discuss the models mechanism of action for removing speckle and enhance image edge of the underwater ultrasonic image. A compare experiment for real underwater ultrasonic image has been done using the method and other traditional methods. The experimental result indicates that the method proposed have strong speckle reduction and enhancement image ability. The purpose of removing speckle noise and enhancing edge at same time has been reached.

Optimal Unimodular Sequences Design Method for Active Sensing Systems

In active sensing systems, unimodular sequences with low autocorrelation sidelobes are widely adopted as modulation sequences to improve the distance resolution and antijamming performance. In this paper, in order to meet the requirements of specific practical engineering applications such as suppressing certain correlation coefficients and finite phase, we propose a new algorithm to design both continuous phase and finite phase unimodular sequences with a low periodic weighted integrated sidelobe level (WISL). With the help of the transformation matrix, such an algorithm decomposes the -dimensional optimization problem into one-dimensional optimization problems and then uses the iterative method to search the optimal solutions of the one-dimensional optimization problems directly. Numerical experiments demonstrate the effectiveness and the convergence property of the proposed algorithm.

Multiple Time-delay Smart Deception Jamming to Pseudo-random Code Phase Modulation Fuze

In order to jam the pseudo-random code phase modulation (PRCPM) fuze, a new jamming method based on multiple time-delay smart deception has been developed. By analyzing the principle of PRCPM fuze, the model of multiple time-delay smart deception Jamming signal and the algorithm of digital have also been established. Moreover, the interference mechanism of multiple time-delay smart deception Jamming signal to PRCPM fuze has been theoretically put forward. The effectiveness of the jamming to PRCPM fuze has been verified by the simulation and the main factors that influence the effect of the method have been analyzed. The results of this paper have certain significance in designing the PRCPM fuzes jamming waveform.

A new method for extracting instantaneous frequency feature of emitter signal

Currently, mostly used method for Instantaneous Frequency (IF) feature extraction of radar signal is two-dimensional graph, which is easy for people to distinguish, but not for machines. This article proposes a feature extraction algorithm based on instantaneous frequency of radiation source. Using the statistical change difference of different IF signals, we formulate the classification feature vectors describing the various types of signal pulse modulation laws, according which we do some classification experiments. The experiments prove that instantaneous frequency characteristics of radiation sources can characterize the change difference of different modulation signals and have some anti-noise performance. We are sure that this method can be used in signal sorting, and can be realized in practice.