Applied Mechanics and Materials Vol. 610

Abstract: This paper briefly analyses the routing establishing process of AODV and points out its imperfection, proposes the AODV routing establishing principle based on SNR. The Network delay and data throughput of the improved AODV have all been improved as simulation results proves. Finally the conclusion was given, illustrating that the improvement avoids the bad influence to the transmission rate of the whole link, which brings by low SNR node, and increases the data transmission efficiency.

Abstract: In this paper, we propose a novel GPS C/A code paralleled acquisition scheme with adaptive threshold setting method. The proposed threshold setting criterion is based on the ratio between the peak and the second peak which determine the signal strength over the noise. For our scheme, the detection and false alarm probabilities are derived. When the length of the received data is 200ms, simulation results show that the proposed scheme improves the acquisition sensitivity by about 2 dB in comparison with the two conventional schemes under various Doppler frequency deviation conditions.

Abstract: According to satellite communication, a novel parameter estimation method based on spectrum feature analysis is proposed. For the satellite communication signals shaped by raised cosine, the scheme enhance the efficiency of power spectrum and the square power spectrum of signals. The proposed method can estimate symbol rate and carrier frequency exactly in the satellite channel without any prior knowledge.

Abstract: A wireless sensor network (WSN) consists of large number of autonomous sensors nodes; these nodes communicate with each other in dispersed manner to observe the environment. WSNs become one of the most important researches in modern communication systems. The energy source of nodes is limited and practically it is impossible to change or charge the battery. In order to save energy and increases the life time of battery in WSNs. Many energy routing protocols using the clustering were proposed in the literature. Low Energy Adaptive Clustering Hierarchy (LEACH) is the most famous routing protocol. In this paper we propose a new algorithm to choose the cluster head which has the highest energy. We shared the network to four regions, between them 90° for each part we find the powerful sensor between the sensors groups, and this last will be the cluster head of this round. Each sensor sends its data to the nearest cluster head and this last will send it to the sink. The same work for five and six clusters heads with sink in the center and in the corner (100, 0) is done.

Abstract: For the implementation of digital multimedia communication, an efficient, reliable, deterministic transmission system plays a vital role. Quadrature amplitude modulation (QAM) is commonly used in digital communication systems. We focuses on simulation and analysis of M-level QAM by using MATLAB in this paper.

Abstract: Based on the basic principles and influencing factors of analyzing routes design, this paper establishes a novel mathematical model for optimal control of routes design with the help of optimization theory. On the condition of satisfying its constraints, the article applies genetic algorithm to process algorithms implementation on the established routes design model. It also further illustrates the feasibility and practicality of routes design model in maritime practice by verification.

Abstract: The Direct Sequence Spread Spectrum (DSSS) signal is widely used because of its good concealment and anti-jamming performance. The Compressive Sensing (CS) theory reduced the sampling rate of the DSSS signal effectively compared with the traditional Nyquist-rate sampling theory. While in the process of CS sampling the sensing matrix and the sparse basis generally have a strong correlation when the DSSS signal is decomposed with a complete dictionary. This paper presents a novel orthogonal pretreatment method with which the incoherence between sensing matrix and sparse basis can be improved. As a result, the reconstructed signal is more accurate. Simulation results demonstrate that this method is effective and efficient.

Abstract: In this paper, the authors employ the M/M/1 system and single-queue and single-server system of gated service, the information packets of Bi-directional cable network are calculated and analyzed theoretically, and the loss rate of information packet is also simulated by computer compared to the theoretical analysis in the paper. Simulation results show that the theoretical analysis and simulation are consistent.And the information packet of Bi-directional cable TV network using single-queue and single-server system’s loss rate analysis of information packet in the transformation provides reference to the theoretical analysis and computer simulation.

Abstract: Software-Defined Networks (SDN), as newly proposed network architecture, has a great potential in optimizing network traffics. In SDN, the control plane is separated from the data plane. With the help of the centralized controller, we can gather information of the network in real time. In this work, we propose a practical two-stage approach for traffic engineering that takes advantages of SDN. The approach not only assures every newly injected flow gets a suitable route that does not have too much payload on it, but also schedules the overall flows so that they are distributed more equally in the network. Furthermore, we demonstrate its efficiency in terms of port speed and compared it with port speed under the default routing decision. We also use linear programming to find the optimal solution and compare it with our result.

Abstract: Material properties in the process of tribo-emission decides the characteristics of both spectra and intensity of triboluminescence. ZnS:Mn semiconductor material was proved to be a high emission triboluminescent material in many investigations; Ce- and Yb-doped hexacelsian possess the excellent shortwave triboluminescence character due to f-d electronic transition of doping element with position valances ions; the fracto-mecha-luminescence and photoluminescence spectra of phthalic acid, 4-hydroxy coumarin monohydrate, etc. present obviously a broad ultraviolet and violet waveband emissions, showing the disadvantage of these organic crystals as shortwave triboluminescence materials. Triboluminescence test apparatus of drop tower type have the tribo-emission of impact friction effect; the pin-on-disk type apparatus can perform the triboluminescent experiments with sliding friction mechanism; the twin ring tribometer is used to measure the triboluminescence of polymer material friction rings. These units supply a suitable conditions for obtaining triboluminescence with shortwave emission and persistent high intensity.