Advanced Materials Research Vols. 383-390

Abstract: The aim of this study is to evaluate the injectable cross-linked chitosan (CS) microparticles (MPs) to apply for biomedical applications specifically for bone regeneration. The CS MPs were fabricated by emulsification method and formed the cross-links between the amide groups in the CS and phosphate groups in the sodium tripolyphosphate (TPP) ionic cross-linking agent. The MPS were analyzed for morphology by Scanning Electron Microscope (SEM). The fabricated CS MPs were in the spherical shape with the size range of 20-100 m. These CS MPs were analyzed for biodegradation by immersing in phosphate buffered saline (PBS, pH = 7.4) at 37°C for 30 weeks. The biodegradation of CS MPs in PBS was initiated at week 25. Mesenchymal stem cells (MSCs) were harvested from the bone marrow of mice tibia and femurs. The MSC attachment on CS MPs was tested using LIVE/DEAD cell sassy with a Fluorescence Microscope. The murine MSCs attachment onto CS MPs at day 2 was confirmed by visualizing fluorescence images. The CS MPs were also analyzed for the injectability and retainability at the site using a subcutaneous injection in a rat model. The fabricated CS MPs possess injectability, biodegradability and biocompatibility. Therefore, these CS MPs have a great potential to apply for various biomedical applications including bone regeneration by injection.

Abstract: Optical, surface and structural properties of ZnO thin films fabricated by reactive radio- frequency (rf) magnetron sputtering and sol-gel coating methods are comparatively investigated. The optical properties of films produced by both techniques have very similar characteristics, however; the surface morphology and degree of crystallinity have different behaviors. The nanostructure columnar zinc oxide thin films can be synthesized by sol-gel coating methods which can have numerous applications requiring larger surface area. Also, the process scalability and large-scale manufacturing of these materials are discussed. It indicated that the nanostructure ZnO thin films can be synthesized with sol-gel methods at wafer levels with nano-grains and improved surface properties compared with reactive rf magnetron sputtering deposition.

Abstract: All the factors causing distribution system faults are analyzed for improving safety and reliability of power system. Comprehensive and scientific evaluation for distribution system faults are made by fuzzy comprehensive evaluation method and the ordering is done by their severities. This method is able to monitor the distribution system safety and reliability and give reference for distribution system condition-based maintenance, thus improve the ability of distribution system safe operation.

Abstract: This dissertation researches on photovoltaic grid-connected generation system. Photovoltaic grid-connected generation system has two core parts which are maximum power tracking control(MPPT) of photovoltaic cells and the control of the grid-connected inverter. Firstly,this paper introduces the operational principle and performance characteristic of photovoltaic cells,and describes the equivalent circuit and mathematical model. Secondly,this paper introduces several traditional MPPT control algorithms. Based on the maximum power of the fast track process and stability, an improved intermittent scan method is designed to implement the maximum power output in the photovoltaic grid-connection generation system and improve system performance and maximum power point tracking speed. Finally, this dissertation analyses the targets of grid-connected inverter control and studies the control strategies, and then designs mathematical model of control system in photovoltaic grid-connected voltage/current inverter based on Sinusoidal Pulse Width Modulation (SPWM).

Abstract: This paper analyses the performance characteristics of NTC magazine, introduces the mode and characteristic of tool selection, discusses the details of the function and the design of the software of the control system. It also utilizes the automatic tool selection of PLC magazine set in the Italian FIDIA CNC and introduces the chart flow of automatic tool selection system. By adopting the brand new Aucol to realize the automatic tool selection program in the magazine, machine tools can improve their productivity in reliability and maintenance. The utilization in production indicates a good control result, which provides an approach of technological innovation for factories.

Abstract: The Stand-Alone wind energy supply system equipped with a doubly Salient Electro-Magnetic Generator (DSEG) is presented in this paper. First, the analysis of the operating characteristics of wind turbine and DSEG is introduced. Based on the strategy of power signal feedback (PSF), the excitation current of DSEG is regulated, as a result, Electro-Magnetic torque of the DSEG is controlled and the maximum wind energy tracking is achieved. Battery is employed as an energy storage device and interfaced to the wind energy system through bidirectional DC/DC converter. The control strategies of the bidirectional DC/DC are proposed to balance the power differences between the generator and the power the load, so that voltage of the DC bus could be constant under varying wind speed and load. The simulation results show the effectiveness of the control methods.

Abstract: System on a programmable chip is designed for the development of embedded system．By embedding a micro_ processor in FPGA．SOPC not only takes the advantage of micro-processor system which is rich in software and hardware resource．it also is a part of FPGA system which has fast logic．So SOPC is considered to be the direction of the future in embedded filed. Meanwhile．This thesis has interpreted the application of SOPC in the monitoring system, and tries to find the advantage and features of the SOPC system by practical designs.

Abstract: Best Neighborhood Matching (BNM) has been shown to be an effective technique to recover a broken image due to a failed network transmission. For high definition image, the time of recovering using BNM algorithm is relative too long and not suitable for real time processing. And the original BNM only targets at gray scale image, and not considers the color image case. In this paper, we extend the BNM algorithm to color image area and use PC clusters to parallelly recover the image and improve the processing speed dramatically. The experiment result from a four nodes cluster system shows that our parallel BNM implementation improves the processing speed up to 7.52 times without any obvious recover quality decrease.

Abstract: It is difficult to apply a traditional strapdown inertial navigation system(SINS) to spinning projectile because of high spin rate. A Roll-Isolated gimbal platform is introduced to prevent SINS by the projectile’s spinning motion. Roll-Isolation is accomplished by supporting the inertial measurement unit(IMU) on a single gimbal, the axis of which is parallel to the projectile’s spinning axis. Roll-Isolation prevents the saturation of the roll gyro by the high vehicle spin rate and greatly reduces the measurement errors arising from gyro scale factor and misalignment. On the basis of roll-isolation, the paper presents a Two-Position initial alignment scheme of SINS on stationary base, which is realized by changing the IMU roll angle around the spinning axis. Furthermore, the paper studies on the observability of the scheme, and the results show that it not only improves observability but also minimizes alignment errors.

Abstract: The purpose of power-fail protection design is to ensure the certainty and integrity of system information. The key point of design includes: the signals of power-fail detection and data treatm- ent; real-time clock circuit design which is synchronous with the system or as a mark of time; using non-volatile memory (such as FRAM) or using battery backup to maintain trade volatile memory (eg RAM) power to ensure the information integrity and non-volatile storage when the power is removed.