Applied Mechanics and Materials Vols. 380-384

Abstract: Digital predistortion (DPD) is a method widely used to compensate the nonlinearity of power amplifier to improve the transmitting signals. The DPD performance, however, depend heavily on the hardware design on signal integrity, EMI and low additional distortion of downconversion circuit. In this paper, a new high-performance hardware solution for DPD is introduced. Engineering tests show that this hardware design characterizes by high reliability and excellent performance to satisfy the requirements of DPD.

Abstract: As high reliable equipment, on-board computer often has difficulties to evaluate its reliability. The paper put forward a simulation method to compute on-board computers reliability. The method uses a forced transition (FT) based reliability simulation model to deal with the on-board computers that have complex structure and diversiform characteristic parameters. The model is particularly suitable for the on-board computers which are composed of the components whose failure processes obey tub life curve. As an example, a prototype on-board computer was put forward and simulated using the model. The presented reliability simulation model can be adopted for the on-board computer probability risk assessment where analytic methods or exact solutions cannot be easily reached.

Abstract: Aiming at the problem of calibrating the INS in non-laboratory conditions, this thesis proposes the calibration methods by as the core and combined use of double-position directional gyro calibration, four-position horizontal gyro calibration and Schuler circuit accelerometer calibration etc. It builds up the model for scale factor calibrating, controls the inertial platform by the embedded control technique to make it the three-axis turntable state, and uses the Linux OS and C language design control software to design and develop the automatic calibration equipment for the INS. This equipment is simple in operation, easy in use and portable, and therefore can realize automatic calibration in non-laboratory conditions. And the results meet the requirements for guarantee the precision of the system in use.

Abstract: Pointing to the unpredictable problems that caused by the priority inversion during the period of using real-time application system, a new improved method, which based on the priority inheritance, was presented. The new method mainly considered the influence that the usage of shared resources impacted on the task scheduling, and recorded the information of each task which asked for the using of system resources by a set of task-shared-resource-link. System would schedule the task according by the records and the task waiting queues. This method was proved as a effective way to solve the phenomenon of priority inversion by experiment in ucos-ii kernel.

Abstract: According to engineering mathematics model of solar photovoltaic cells, a simulation model of photovoltaic cells was established in Matlab. In view of problem that it is difficult to get higher tracking accuracy and response speed by use of perturbation and observation method which applied fixed perturbation step, the paper proposed an improved perturbation and observation method based on variable step. Through simulating photovoltaic cells control system, simulation curves of two kinds of methods of maximum power point tracking were compared. The simulation results show that the photovoltaic cells control system can track maximum power point more quickly and has better stability at the maximum power point by use of the improved perturbation and observation method.

Abstract: In this paper, we present a new traffic dispatch policy for a power-aware router, which was named GreenRouter and was proposed in our previous publication [. Packet processing capacities, mainly including IP lookup and forwarding engines, are shared and modulated according to traffic loads, unoccupied capacities are powered off in order to save power. A flow based traffic dispatch policy was proposed to allocate traffic from network interfaces to processing engines dynamically. Significant power saving has been achieved while QoS constrains have been satisfied. We present a new packet-based dispatch policy for GreenRouter in this paper, which can achieve more power saving. Reordering is adopted to avoid out-of-order delivery.

Abstract: With the massive development and application of wind energy, wind power is having an increasing proportion in power grid. The changes of the wind speed in a wind farm will lead to fluctuations in the power output which would affect the stable operation of the power grid. Therefore the research of the characteristics of wind speed has become a hot topic in the field of wind energy. In the paper, the wind speed at the wind farm was simulated in a combination of wind speeds by which wind speed was decomposed of four components including basic wind, gust wind, stochastic wind and gradient wind which denote the regularity, the mutability, the gradual change and the randomness of a natural wind respectively. The model is able to reflect the characteristics of a real wind, easy for engineering simulation and can also estimate the wind energy of a wind farm through the wind speed and wake effect model. This paper has directive significance in the estimation of wind resource and the layout of wind turbines in wind farms.

Abstract: In this paper, a cell equalization circuit based on the Flyback topology is proposed for the Lithium-ion battery pack. Multiple transformers are employed in this circuit, equal to the number of cells in the pack. All the primary windings are coupled in series to provide the equalizing energy form the whole battery pack to the specific under charged cells. The structure and principle of the circuit is discussed, finally a prototype of four cells is presented to show the outstanding equalization efficiency of the proposed circuit.

Abstract: The embedded digital-analog mixed-signal circuit testing has become one of the difficulties to be solved. In this paper, a SoC embedded ADC has been tested based on the Credence Gemini500 verification system. The testing method is studied and verified through the test experiment and results. This testing method is an important reference for general embedded IP core testing.

Abstract: In view of the harsh and variable underground environment, the current existing coal mine monitoring system is difficult to expand and has monitoring blind spot. Based on CC1110 chip and SimpliciTI network protocol, we present a design scheme of underground wireless sensor network which relies on automatic monitoring and alarm to the mine area environmental parameters. First, introduces the system composition structure, and the hardware design of independent communication subnet. Secondly, explains the system network protocol, network access mechanism used of periodic synchronous, and channel prediction. Finally, describes the software design of monitoring nodes. The test results show that the network nodes have many characteristics such as long-distance communication, movability, build up flexibly, high stability, and so on.