Applied Mechanics and Materials Vols. 713-715

Abstract: In this paper, a approach for frequency 12-tupling millimeter-wave generation using one DPMZM (Dual-Parallel Mach-Zehnder Modulator) to overcome chromatic dispersion is demonstrated. The millimeter-wave with the baseband signal carried only by minus 6-th order sideband is generated by properly adjusting a series of parameters. As the signal transmittes along the fiber, there is no time shift caused by chromatic dispersion. Theoretical analyses and simulated results show that when the optical mm-wave carrying 2.5Gbps baseband signal transmits over 55 Km, the eye diagram still keeps open and clear. The power penalty is about 0.7 dB after transmits over 40 Km.

Abstract: Symbol synchronization offset of orthogonal frequency division multiplexing (OFDM) communication system will cause the rotation of data constellation at receiver even if such offset falls in the range of the appended cyclic prefix. When OFDM modulation is combined with spread spectrum technique, e.g., OFDM code division multiple access (OFDM-CDMA), the problem becomes more serious since OFDM-CDMA communication system generally works under very low signal-to-noise ratio. This paper focuses on symbol timing synchronization of OFDM-CDMA communication system and proposes an effective sequence structure on the basis of circular conjugate-symmetric properties of discrete Fourier transform. The proposed frequency-domain sequence not only can generate real time-domain signal to reduce calculation complexity, but also can resist peak-to-average power ratio of OFDM modulation by exploiting suitable computer search algorithm. The simulation results show a sharp cross-correlation peak can be obtained, which is quite helpful for accurate symbol timing synchronization of OFDM-CDMA communication system.

Abstract: Reasonable allocation reactive power compensation devices in coal mine system can not only develop power factor, it can also solve bus voltage fluctuation problem of coal mine system. By analyzing load characteristic in coal mine system, non-linear impulse load and induction motor can cause bus voltage fluctuation. The characteristic of SVC is that its response speed is quick and it can be adjusted continuously. But the price of SVC is expensive. Reasonable allocation method is that a portion SVC is installed in the bus that are connected with a number of non-linear impulse load and induction motor, SVC is only used to undertake fluctuation load. It can solve voltage fluctuation problem well. Simulation and analysis on WSCC-9 bus system testifies the validation of the proposed method.

Abstract: For the current avionics system structure of typical military aircraft, this paper proposes the architecture design of airborne embedded training system ,and detailedly discusses the functional structure scheme of the training system, composition of hardware and software etc. This paper deeply discusses credibility and effectiveness inspection scheme in the system development process, and takes embedded training system and the integration process of the fire control radar for example, this paper also does simulation and analysis of simulation.

Abstract: The output characteristics of a PV array vary nonlinearly when the number of solar cells interconnected in series and parallel changes. The model and its parameters for a single solar cell are analyzed firstly. Then the models and there parameters for series, parallel circuits and series-parallel PV array are proposed respectively using circuit theory and observational method. Especial, the parameters of the equivalent circuits for PV arrays are characterized by a equation. A simulations are implemented to verify the three types of theoretical models and there parameters.Keywords: Solar cell; Model; PV array; I-V curve; Equivalent circuit

Abstract: In cellular networks, Device-to-Device (D2D) communications can improve spectral efficiency and increase overall throughput. However, D2D users may cause interference to the cellular users (CU) due to sharing resource with CUs. In this paper, we proposed a resource allocation scheme to maximize the system throughput while guaranteeing the quality-of-service (QoS) requirements of all communication links. The proposed scheme allows as many D2D pairs as possible to reuse resource and includes three steps. Firstly, an exhaustive search method is used to search out all the reuse combinations, in which all users share the same resource. Secondly, transmit power for each reuse combination is allocated. Lastly, a suboptimal but simple algorithm is proposed to select suitable reuse combinations in order to maximize the overall throughput. Simulation results show that the proposed scheme can significantly increase system throughput and D2D access rate.

Abstract: In this paper, we consider the device-to-device (D2D) communications with multiple antennas underlaying single-cell cellular networks, in which D2D transmission links reuse the cellular downlink (DL) resource. We propose an iterative distributed interference alignment (IA) algorithm to reduce the cellular interference towards D2D UEs, which utilizes the reciprocity of wireless networks with local channel knowledge at each node. The iteration algorithm continues until it converges, judged by the weighted leakage interference (WLI). Simulation results demonstrate that using the distributed interference alignment algorithm can effectively improve the system capacity and energy efficiency.

Abstract: A technique for a reconditioning equalizer filter for non-constant envelope signals is described. The input to a transmitter chain is modified by a reconditioning equalizer filter, prior to being applied to the transmitter. The reconditioning equalizer filter modifies and smoothens the amplitude of the signal. The modified and smoothened signal has its peaks reduced which results in lower Crest Factor. The input to the reconditioning equalizer filter could be a baseband, intermediate frequency (IF) or radio frequency (RF) signal. When the signal is an IF or RF signal, it needs to be down-converted to baseband before being applied to the reconditioning equalizer filter. The reconditioning equalizer filter could be performed in a digital or analog domain.

Abstract: Strong electromagnetic pulse protection is very important. We must solve the electromagnetic compatibility problem between the circuit components, the ship equipments and internal information systems, and ensure the electromagnetic compatibility of the protection measures. This paper analyzed the requirements and reinforcement targets. It also put special stress on analyzing the basic method and principle of reinforcing platform.

Abstract: Four quadrant inverter used for mine consists of SEOHO[1] inverter of South Korean and explosion-proof cabinet and a series of hardwares and softwares (be in conformity with safety standards of mine). Applied in coal mine machines, making reasonable braking by using the principle of energy feedback. It can meet the special requirements of the mine lifting equipment, and providing the energy feedback to grid so as to strengthen braking effect and so on. In addition, SEOHO inverter of the South Korean has a special active-front-end (AFE), AFE rectifier unit/feedback [2] derive sine wave AC from the grid, generating DC voltage output by rectification, and maintaining the required voltage value. Every harmonic wave is deleted by filter circuit. Meanwhile, the huge economic benefits and energy-saving profits have been gained when the four quadrant inverter is used.