Applied Mechanics and Materials Vols. 195-196

Abstract: In this paper, a new Doppler shift estimator is proposed for Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) over railway environments. Different from other existing methods, which commonly assume that the fading channel coefficients are available for the Doppler estimators, the proposed estimator is developed based on the signals which contain unknown frequency selective fading channel coefficients, unknown Rice factor and random receiver noise; it contains three steps. The statistical properties of the training symbols which are called near independent identically distributed (i.i.d.) training sequences, i.e., midamble, are first analyzed. Afterwards, by the help of a training sequence, the second-order and fourth-order statistics of the received signals are calculated. Then, by exploiting these statistical results, the Doppler shift estimator is obtained. The proposed estimator employs a smoothing function with corrective factor. By optimizing the corrective factor, an accuracy solution is acquired within the Doppler shift range of possibilities. Simulation results indicate that the proposed estimator is greatly reliable and effective to estimate Doppler shift up to 400 Hz.

Abstract: According to the relevant criterion and principle of trusted computed module design and application, we have designed a trusted SoC chip, and have given the implementation of the basic function. In detail, we have discussed the design of trusted SoC chip security architecture and the main module function, the reliability of relevant parameter and transfer strategy of trusted root in chip development and application, together with the simulation and validation of relevant function. At last, we point out that one of the most important further research directions is the trusted measurement of dynamic data and security environment.

Abstract: Since the original CIM-SPL policy language does not support access control policy, the CIM-SPL is extended with the RBAC model in this paper. Then a new CIM-SPL based RBAC policy language is designed and implemented. The syntax specification of the new policy language complies with the original CIM-SPL. So it is quite suitable to describe access control policies for information systems specified by CIM. The implementation framework of the new access control policy language is based on the IETF PDP/PEP approach and is integrated in the Open Pegasus system which is the most widely used open-source software of CIM implementation. At last, a case study of Health Information System is used to demonstrate the flexibility and applicability of the new access control policy language.

Abstract: An Internet of things system using Cyclone EP2C8 FPGA chip of Altera is designed and researched in this paper, which integrated NiosII soft-core processor, memory, functional interfaces with SOPC (system on a programmable chip) technology. The μC/OS-II embedded operating system is transplanted here to realize the network communication through driving the network chip. Simultaneously, the message stored in card can be correctly identified, recorded, added up by RFID technology, and sent to internet according to the requirement of communication. Thus, the internet of things function is realized.

Abstract: Wenchuan Earthquake occurred in Wenchuan, Sichuan Province, China, and numerous geo-hazards broke out simultaneously and landslides, collapse, debris flows pose a great threat to the security of life and property in earthquake hitting area. The post-earthquake geo-hazards, especially landslides will continue for years. Based on the North Mountain landslide triggered by Wenchuan earthquake in Fengxian, a new landslide monitoring principle that sliding force is greater than the anti-sliding force is the necessary and sufficient condition to occur the landslide is put forward, earthquake and rainfall condition also are take into consideration. According to the results of engineering geologic investigation and numerical simulation, the burial depth of potential sliding surface is determined, and the functional relationship between sliding force and perturbation force is set up. According to above analysis, two sets of Landslide remote monitoring systems (abbreviated SPRM-01) are installed on North Mountain Landslide, and around 15 months monitoring data are collected, based on these data two sets of monitoring curves are obtained, which can indicated the change feature of sliding mass and the analysis results provide scientific basis for the stability analysis and hazard assessment of sliding mass.

Abstract: Wireless communication technology has been used widely, different technologies have different application range and applicability. In this study, several commonly used wireless communication technologies were comparatively analyzed on the transmission rate, use cost and power consumption, and so on. It is concluded that the characteristics of ZigBee technology accord with the research needs, and it has many advantages in landslide disaster remote monitoring applications. Wireless sensor network was established based on ZigBee technology, then planar landslide information acquisition transmission system was developed, and immediately applied in engineering fields. Application results show that the system runs stable, and its effect is really good, which provides powerful support for later promotion.

Abstract: The Constant Modulus Algorithms is a mature algorithm for a long time. The researchers are fond of its solidity. But in the area of shallow sea or blue sea, the CMA has poor constringency. In this passage, based on a improved blind equalization algorithm, we proposed a new algorithm which suitable for sparse underwater acoustic channel. The computer simulation results demonstrate fast convergence and fewer accounts.

Abstract: In CR systems, resource allocation is very important, which can be operated by different rules, according to the different purposes. In this paper, we focus on subcarrier allocation in CR systems, where primary and CR users co-exist in adjacent bands, while keeping the total interference introduced to the PU band below a certain threshold and the total power allocated to the CR users under a constraint. First, we investigate Max-Rate subcarrier allocation algorithm (MaxR-SAA) which can achieve maximum transmit rate of the CR system. Then, focusing on the fact that the less interference introduced to the PU band, the better the PU can work; we proposed a Min-Interference subcarrier allocation algorithm (MinI-SAA). Further, aiming at achieving fairness among all the SUs, we propose a subcarrier allocation algorithm, which is termed as Fair-Rate subcarrier allocation algorithm (FairR-SAA). Numerical results are obtained for the behaviors and performance of our proposed algorithms.

Abstract: The impact of Doppler frequency hopping on code tracking performance is simulated. A design on pseudo-noise (PN) Code Tracking Loop aided by the carrier tracking loop according to the carrier frequency hoping pattern is proposed in this paper. This scheme can be applied in the Telemetry, Tracking, and Commanding system which uses Direct Sequence/Frequency Hopping Spread Spectrum (DS/FH) hybrid spread spectrum technology. Simulations of the code tracking loop under different carrier to noise ratios are compared based on this scheme. The results show this method on PN code tracking of DS/FH signals is valid.

Abstract: Suppressing jitter noises and keep precise track is of great importance in coherent communication systems. This paper proposes and analyzes a new extended kalman filter (EKF) based carrier recovery loop for high dynamic and low carrier-to-noise ratio environment. In this algorithm, EKF filter take the phase error between input signal and local oscillator and has a simple measurement equation. Simulations show that the method is feasible and has good performance.