Applied Mechanics and Materials Vols. 556-562

Abstract: It requires a large number of temporary ground wires for maintenance tasks in distribution network. Because the temporary ground wires can be grounded anywhere, it is difficult to check their states and control them. Currently solutions are generally expensive in city-scale. This paper presents a method that integrates the complex monitor, control and communication modules into a pocket computer key. The abundant of ground wires are controlled by a simple electric lock, which will downgrade the cost of whole system. This paper also proposed a graph-base temporary ground wire management algorithm, which utilizes the Boolean adjacent matrix to determine the ground operations. The experiment results show that algorithm is more efficiency the baseline of the Topological Analysis Algorithm and the Logic-based Analysis Algorithm.

Abstract: Nowadays, various test equipment tend to be more intelligent, the test equipment of the volt-ampere characteristic of CT is so too. As the development of the electronics, VLSI(SCM) is manufactured. The purpose of our project is to scheme out a intelligent test system by the computer technique and the test technique. This equipment is mostly made of the SCM system and the peripheral equipment. We control the output of the digital transformer by SCM. The output voltage can make the TL494 create PWM wave. The wave is the control signal of the main circuit. The output wave of the main circuit is the sine wave, and the value of the output can be amended automatically. Compared with the traditional equipment, this equipment is smaller and use less energy, but its function is more powerful. It can be programmable. We can take it more expediently. So, this kind of equipment can be used widely in the future.

Abstract: With the rapid development of network bandwidth, the matching-performance of regular expression is gradually of crucial importance for networking security. There are many hardware acceleration designs of regular expression matching on the basis of NFA and DFA, of which NFA designs require more logic circuit resources while the DFA designs more memory resources. However, because there are too many states and transition edges in DFA, the performance of DFA is much inferior to the performance of NFA. In this paper we designed a DFA regular expression matching algorithm fully based on FPGA logic circuit. The algorithm exploits the feature of DFA that many transitions for a state may have the same next state pointer and setting a default transition for each state of DFA will result in the reduction of logic circuit and the simplification of the electronic circuit. To evaluate performance, this DFA algorithm was mapped onto the Altera Cyclone FPGA, and got the experimental results based on the L7-filter rule set. The performance of the DFA algorithm acquired an approximate performance compared to the NFA algorithm. Experimental result shows that, compared with the NFA algorithm, in the improved DFA plan, 10% rules got a higher throughput, reaching 60% in the best case; while 62% rules cost less logic resources, saving 87% logic resources in the best case.

Abstract: According to the rapid development and widespread application of virtual instrument technology, a design with serial port and the audio card of PC as the main hardware and LabVIEW as the software development platform is proposed. Not only can it generates and output basic waveform, arbitrary formula wave and hand-painted waveform in real time, but also realizes the function of the oscilloscope system, including: channel selection, collecting and display waveform data in real-time, parameter measurement, spectrum analysis etc. This multi-functional virtual instrument has the advantages of friendly-machine interface, easy to transplant and modify and good scalability. And it has broad prospects in the field of testing, measurement and teaching practice.

Abstract: This paper presents a novel architecture for mixed-signal SoC, which integrates a Field Programmable Analog Array (FPAA) into a SoC based on 32-bit RISC CPU. The FPAA unit can be configured as Filter, Comparator, Gain Amplifier, and so on. The proposed mixed-signal SoC can transform the intermediate frequency (IF) analog signal to baseband digital signal and realize the real-time baseband signal processing, besides this, which can transmit the modulated IF signals which are converted from baseband signals by digital up-conversion (DUC). The proposed mixed-signal SoC is a transceiver on chip actually, due to the internal integrated IPs, such as ADC, DAC, DDC and DUC, which can provide smaller board area, lower power consumption and the system cost for the product development of transceiver. This design will have a good potential for wireless communication applications.

Abstract: Noise is one of the most significant indicators to measure the performance of the PMT, which is regarded as a photoelectric detector. Moreover, the excess noise factor F is an important parameter to describe the noise. Excess noise factor expressions for PMT in different situations are derived and analyzed by simulation in this paper. Some numerical simulations are made to obtain the maximum and minimum excess noise factor F and the changing trend of F with each parameter. From the analysis, we can minimize the noise for PMT to increase the detection precision as a photoelectric detector.

Abstract: LDRI system stands for Laser Dynamic Range Imager. It has been used in STS-114 mission in 2005 as the main sensors to realize an on-orbit inspection of the thermal protection system which covers the Orbiter spacecraft. The basic of LDRI is phase discrimination and the key technology is the realization of optoelectronic mixing (OEM) using ICCD. Unfortunately, 2 main drawbacks arise from the usage of ICCD, including the high voltage (~2000V) of PMT drivers and the difficulties in high voltage modulations. SiPM is a rather novel detector which has the similar performances as PMT does but only requires a driving voltage of about 30V. Recently, the SiPM based OEM has been proved and this implies the implement of SiPM in LDRI system. In this paper, the basic of LDRI and SiPM are summerized and some theoretical analysis and simulations are made to verify the feasibility of implement of SiPM in LDRI system. The results show that SiPM is capable of realizing phase discrimination regardless of the high driving voltage and difficulties in modulations. The mean range error is found to be no more than 0.4mm within a range of 5m and an average incident power of 6nW.

Abstract: The control strategy based on predictive current is proposed to solve problems that destruct stable operation of grid-connected photovoltaic system during asymmetrical fall. A mathematical model of PV inverter is established to calculate current instruction; a method of tracking based on predictive current is proposed to reduce the fluctuations of 2 times frequency. In the meantime, PV inverter provides reactive power to support voltage recovery according to the depth of grid voltage sags and realize LVRT. The result also shows that the proposed control strategy can reduce wave of DC voltage and provide reactive power to support voltage recovery.

Abstract: The traditional firewall is a protect mechanism usually between the internal and external network, through the input and output of data packets in real-time network monitoring, it will make protective response immediately if it find security threats. With short data processing time and high efficiency, it can satisfy most procedures of application, but it has high cost and is difficult to achieve. In this paper, in view of these problems, embedded firewall security protection mechanisms set based AMR processor innovation, given the overall framework of embedded firewall hardware and the design for software architecture ,I selected good performance S3C2410X embedded chip, the embedded firewall network card drivers, key technologies of application research in detail, based on the embedded firewall performance of AMR processor through the contrast test ,the communication rate can reach 15.5Mpbs, 2.15times higher than that of general processor communication performance.

Abstract: In this paper, we use the adaptive function model to improve FPGA digital pre-distortion technique, design the adaptive pre-distortion function and algorithm, and adopt PC-CFR technique to process digital distortion problem in high order modulation, and obtain very good effect of digital signal processing. In order to verify the validity and reliability of PC-CFR technology, we use Agilent 89600 VSA software to exquisite power output signal before and after the broadband power amplifier pre-distortion. The results shows that before PC-CFR pre-distortion processing, phase difference of AM/PM reaches a maximum of 0.258, signal distortion is more serious; and after the PC-CFR pre-distortion processing, phase difference is only 0.021, the minimum is 0.005, which controls the distortion signal and improves the signal transmission quality. It provides technical reference to study the broadband power amplifier technology.