Applied Mechanics and Materials Vols. 198-199

Abstract: This paper contains a review of technologies, theoretical studies for optical communications from and to high-altitude platforms (HAPs). We discuss how to use optical communication to transmit data at multi-Gigabits in HAP to HAP and HAP to Satellite. The influence of the atmosphere, background light and other noise are discussed in this paper, we explain the advantages and disadvantages of free-space optical communications. And the performance of HAPs (High Altitudes Platforms) WiMAX is studied for different HAPs heighth and transmitted power level in different transmission format. The coverage radius increases with the transmitted power increment and with the operating frequency reduction

Abstract: In order to acquire the multi-points physical signature of the ocean environment,a distributed measurement system was designed. Because of using virual instrument and ethemet technology, the system can measure the multi-points physical signature synchronously.The hardware part of the system contains measurement nodes, central electrical cabinet and measurement stations.The soft part which modular and open design method is used in is based on LABVIEW developing workbench,achieving the automatic physical measurement , real time display,data processing and management.. The experiment results prove the system effective.

Abstract: The technology of Amplify-and-forward cooperative diversity is popular for the cooperative communication system. And it can be applied when a communication terminal can’t communicate with other communication terminal directly. Moreover, this kind of scheme has been studied by the researchers for the application of terrestrial wireless communication systems. The conventional system presents that the power are equally distributed among all nodes. However, this algorithm can not be applied to satellites communication systems directly. Therefore, an improved Amplify-and-Forward cooperative scheme is presented in this paper, and the simulation results show that it can obtain the larger system capacity and better BER performance.

Abstract: The most important quality indexes to evaluate pulp washing performance are residual soda and the Baume degree. But it is difficult to measure the two indexes directly. To solve the problem of optimization control of the washing process, the model of the residual soda and the Baume degree are studied in this paper. Simulating residual soda and the Baume degree via a two-step neural network and modeling them based on least square method and steady-state data obtained by neural network model. Simulation results show that this method can effectively locate the pulp washing process.

Abstract: This paper explains the importance of Ethernet communication in practical application, and designs an Ethernet communication soft-core based on FPGA. The soft-core proposed in this paper can implement data transmission and reception based on UDP Protocol stack. It can receive and unpack UDP protocol packet and extract the data out of the packet; it can also pack and send UDP protocol packet in preset length. The whole application is modeled in Verilog HDL. Experimental results show that the maximum frequency of proposed design is 100Mb/s, which is sufficient for most applications.

Abstract: A novel microstrip bandpass filter using stepped impedance resonators (SIRs) with asymmetric open stub-loaded is proposed in this paper. The filter uses asymmetric open stubs as capacitive loads, resulting in higher-order spurious frequencies suppression and wider upper stopband. Compared with the traditional filter based on stepped impedance resonators at the same design frequency of 2.4 GHz, the proposed filter can significantly reduce the circuit size of 45 %. By changing the geometric dimensions of the asymmetric open stub-loaded SIRs, which can achieve single-band bandpass filter at the centre frequency of 3.5 GHz and dual-band bandpass filter at the centre frequency of 2.4/3.5 GHz.

Abstract: Satellite channel is a typical band-limited and non-linear channel, and 8PSK signal with continuous phase (CP8PSK) is proposed to provide better SER performance in the channel. CP8PSK has higher bandwidth efficiency than GMSK and SOQPSK. Although CP8PSK’s SER performance is 1.5dB worse than traditional 8PSK signal in the Gauss channel, it has better performance in nonlinear satellite channel. With theory analysis and simulation, this paper compares the characteristics of 8PSK and CP8PSK working in the nonlinear satellite channel, especially considering the situation when the amplifier working in the nonlinear area.

Abstract: With the explosive growth of wireless applications, the subscribers’ requirements of QoS (Quality of Service) are increasing as well. In this paper, the upper bound of the tolerant delay of services in wireless access network is investigated, by mapping core network onto a cost-variable directed graph, where the cost is construed as the average service delay of the flows traveling in core network that depends on the current load. A multicommodity minimal cost flow mathematics problem is then derived and solved by Price-directive Decomposition and Lagrangian Relaxation. Simulations are carried out in two typical core networks and some valuable conclusions are gained.

Abstract: According to the unsafety exist in the steel cord conveyor belt running, introduces the design of a new steel cord conveyor belt online testing system which based on ARM and sensors array, describes the system hardware, software, and testing results in detail.

Abstract: A Wideband Signal Generation System for radar and Electronic Warfare is presented. This system uses two DACs each can work at 1Gsps with 14-bit resolution and generate 500MHz bandwidth signal. The DDWS (Direct digital wave synthesis) method is used for signal generation and the data transfer and controlling is based on FPGA. The data for signal generation is stored in ZBT-SRAM and the system can communicate with the controller module through PC104+ interface. The system structure, implementation and test results are described in detail.