Applied Mechanics and Materials Vols. 716-717

Abstract: The main task of bootloader is to copy the kernel image to RAM , and then jump to the entrance of the kernel to run the operating system . It is the first-running code when the system is powered on . U-boot , with its open-source codes , supporting for varieties of embedded operating system kernel , high reliability and stability , has been in the mainstream of bootloader . However , it has not yet provided the original support for the S3C2440 processor , neither does its NAND flash . This paper analyzes two flashes in reference to the corresponding start-up mode , and introduces the U-boot start-up procedures briefly and figures out the major steps of transplanting U-boot to the target platform . U-boot was transplanted successfully .

Abstract: Using the TTS technology and Svox engine in the Android platform, this paper puts forward the design scheme of the speech navigation system based on Android. The Android platform and structure are introduced firstly, then the system structure and functions are detailed described, lastly the key technology and implement way is given. This system developed methods for the visually impaired application areas have certain guiding significance and the actual practical application value.

Abstract: For the low management of current collective electricity, this paper designs multi-route intelligent electric system, and introduces the soft and the hardware design of the system in detail. The system uses STC enhanced SCM as the control core and communication, based on BL0932B chip, designs single phase bidirectional power electric energy metering module, and uses 485 bus and GSM module as communication and control methods. The actual application shows that the system has high intelligence, reliable operation, achieving the desired effect.

Abstract: In the electronics industry, people has higher and higher demand for the performance of electronic products, but the requirement of volume is more and more small, it will promote the electronic products toward the direction of miniaturization. Porous ceramic capacitor is one of the most commonly used small electronic devices, but the capacitor thermal failure problem is always a difficult problem plagued capacitor design. This paper establishes the mathematical model of porous ceramic capacitors failure stress, and ABAUQS software is introduced to the failure simulation calculation process of porous ceramic capacitor, to establish the numerical simulation model of capacitor. Through the boundary conditions, the capacitor’s maximum failure stress are calculated, the failure force and the relationship between the thickness of dielectric layer and ceramic layer are obtained, which provide a new computer method for the design of porous ceramic capacitor and the study.

Abstract: Discharges in the transformer are important symptoms to assess degration of its insulating structure. The indexes of q, φ, n and dissolved gases have been used for many years for diagnosis discharges of oil filled transformers. In this paper, one discharge experiment for needle-plate model is performed. To investigate the difference of indexes to evaluate the severity of discharges, a new energy index is proposed and all the indexes including maximum apparent discharge (Qmax), average apparent discharge (Qave), frequency of apparent discharge (Qfre), phase position of apparent discharge (Qpha), total hydrocarbon concentration (THC) and the new energy index are analysed. It is found that the best performance of all these indexes to evaluate the severity of discharges is W which rises with discharge process and increase rapidly in the end.

Abstract: Dynamic reactive power optimization of power system is an important means to ensure grid economic safety. Unlike static reactive power optimization, dynamic reactive power optimization has to consider the reactive power compensation devices switches and number of constraints of transformer tap stalls. The number of constraints undermine the independence of each period, each time reactive power optimization scheduling interrelated, so dynamic reactive power optimization must be considered from the entire period of time to compensate the number of constraints of the devices, and how to deal with action number of constraints is difficulty and focus of solving dynamic reactive power optimization of the power system.

Abstract: The paper briefly investigates the importance of power control of HVDC (high voltage direct current) control system in the HVDC projects and focus on the actual analysis and research on the realization of automatic power control in HVDC transmission. It has the important guiding significance for the implementation of automatic power control in HVDC transmission.

Abstract: In this paper, the overview of ZigBee technology is firstly introduced. Futhermore, in order to evaluate the feasibility of voice communication over ZigBee network, this paper takes ZigBee as a wireless communication technology to investigate wireless voice communication. The results show that the voice communication based on ZigBee technology turn out to be effective.

Abstract: To introduce extra coding gain to Multi-input Multi-output (MIMO) system, how to combine MIMO and convolutional code (CC) was studied in two cases. In the first case, the type of MIMO was limited to pure spatial multiplexing. Then in the second case, the type was extended to the hybrid of spatial multiplexing and transmission diversity. Several encoding-decoding schemes were designed. For each scheme, its advantage and disadvantage were analyzed, and bit error rate performance was evaluated by simulation. Finally the scheme with best performance and acceptable complexity was elected from candidates for each case.

Abstract: Recently, Multi-bit flip-flop usage has shown its advantage in dynamic power saving in nowadays commercial electronic design. This paper present a more comprehensive comparison of chip-level synthesis result by using single-bit flip-flop and multi-bit flip-flop standard cell and except for analyzing the power and area benefit from replacement under the maximum speed, this paper give a compromise solution to solve that using multi-bit flip-flop cannot run as the fastest as single-bit with even large area. The trade-off between a multi-bit flip-flop cell driving strength and its area when designing multi-bit standard cell that will greatly influence synthesis result as speed arise are also mentioned. Finally, this research about MBFF further usage improvements may be helpful for designers to know how to take full advantage of multi-bit flip-flops to bring about the wanted benefit.