Applied Mechanics and Materials Vols. 55-57

Abstract: A new approach to synthesize the different methods of reliability allocation based on D-S theory is presented in order to obtain a reasonable result in the reliability design of a system. Firstly, introduced the background of the question and D-S theory; secondly, summarized the main methods available of reliability allocation; thirdly, presented our approach of reliability allocation, and gave an example applied the approach; and finally, reached the conclusion that the approach is effective for reliability allocation.

Abstract: At IWSEC 2008, F. Guo et al. proposed an efficient short signature scheme with batch verification based on C. Gentry’s scheme. In this paper, we firstly propose the key substitution attack on F. Guo et al.’s digital signature scheme and show that the malicious adversary can forge a valid signature, which can be verified with a substituted public key. Secondly, we prove that F. Guo et al.’s scheme is malleable and the attacker can produce a new valid signature on the message if he/she has known some valid signatures on the same message.

Abstract: A new vibration source number estimation method based on Fast Fourier Transformation (FFT) is proposed. The frequency spectrum characteristic of vibration signals on a machine was analyzed. The characters of the vibration sources were obtained by means of FFT, which was used to estimate the number of vibration sources. The estimations illustrate that the presented method can obtain the correct source number not only under the condition of less source number than that of measurements. The most important is that it can get the source number correctly on the case of more source number than measurements’. The method gives a new idea to estimate the real vibration sources number.

Abstract: The tested samples by adding 1.0% nano-copper powder and Fe-base powder mixed with globe grind violently are sintered at 600, 650, 700, 750, 800, 850°C, and keeping temperature 30 minutes and 1, 2, 3, 4 hours at 600°C. The nano-copper morphology changes of impacting fracture surface are observed by scan electrical microscopy (SEM). The results showed that the nano-copper particles occur adsorption rapidly, diffusion and dissolution at Fe-base powder particle interface with increasing sintering temperature at the same keeping temperature times and extending keeping temperature times at the same sintering temperature. The nano-copper particles grow up by reunite and existing unconventional growimg up critical temperature Tc. The nano-copper particles dissolve at the nano-Fe powder surface at the lower sintering temperature, and decreasing the sintering temperature to 920°C.

Abstract: Based on parameters and design requirements of the original LJ276M gasoline engine, using Helmholtz theory to calculate resonance frequency, intake manifold length and diameter and other structural parameters, rapid design a new resonance intake system. And then apply simulation software GT-Power to build working process model of the LJ276M Electronically Controlled Gasoline engine, and determine the final structural parameters of the intake system through the use of rapid prototyping and test verification methods. Compared with the original machine, the dynamic performance is improved significantly by the use of optimum design of the intake system.

Abstract: Based on the microcontroller C8051F340, a roadway test system was designed for motor vehicle's longitudinal performance testing, such as acceleration and braking performances. The sensing device was comprised of GPS system, braking switcher, steering angle sensor and combined sensor, etc. The last two sensors were selected from vehicle electronic stability control system ( ESP ), which offer CAN (Controller Area Network) interface and all the data update frequency was 100 Hz. The GPS device's data update frequency is only 1 Hz, but its accuracy of speed measurement is 0.1 km/h. In order to get the precise travel distance and 100 Hz speed information, a data fusion algorithm was employed based on the speed information from GPS and the vehicle longitudinal acceleration information from the combined sensor. These sensors were selected according to the requirements of the laws and regulations of vehicle performance test. All the sensors' interface protocol, system hardware design, microcontroller and portable computer's program design were introduced in detail. Finally, a confirmatory road test was conducted to verify the system’s correctness and reliability. With those advantages of low cost, expandable interface (CAN bus) and moderate accuracy, the designed system can offer an advanced test platform for the research of vehicle braking and acceleration performances.

Abstract: The main characteristic of a multilevel inverter is able to reduce each power device voltage stress. Static Synchronous Compensator (STATCOM) is the major application of the inverter to compensate reactive power in power system. The proposed strategy is simple, high precision, fast response speed, while it has less fluctuation with the impact of load parameters, and good robust characteristics. STATCOM employing the multilevel inverter provides good performance such as enlarging capacity and decreasing even frequency harmonics, and the control of alternation working switch order based PWM can be applied in related research fields.

Abstract: In this paper we propose a hybrid method of literature recommendation in the academic community. First, we refer the objective recommendation based on HITS algorithm by constructing a directed graph according to the literature citation relation and then select the articles considering the authority and hub score of each article synthetically and add them to the recommendation list. This can narrow the recommendation scope and give a more authoritive recommendation. Second, the subjective recommendation is based on collaborative filtering by comparing the ratings of other similar users for the objects in recommendation list. The difference is we discover the similar user by clustering them. And the experiment shows the method can provide better recommendation results and is timesaving.

Abstract: More and more malicious codes spread faster than ever and make the traditional anti-virus technology based on virus signatures to encounter unprecedented difficulties. People try to seek inspirations from Nature. The biology immune system provides a novel idea for malicious codes detection. Inspired by the features of MHC (Major Histocompatibility Complex) in the biological immune system, we propose an MHC-inspired method for malicious codes detection to effectively detect previously unknown malicious codes. The antibody (detector) consists of the constant region and the variable region. The constant region, filled with MHC genes, is to preserve outstanding antibody genes. The variable region, composed of other antibodies genes fragments, is to improve the antibody diversity by mutation. The dynamic evolution of self and nonself, the presentation of antigen, and the generation of antibody are discussed. The experiments are conducted and the results indicate that the proposed method has relatively higher detection rate of unknown malicious codes than AISCSA, a typical immunity-based method for malicious codes detection.

Abstract: A one step sol-gel method was used for preparation of Cu doped titania nanoparticles (NPs). The crystal structures, morphologies and chemical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). We discussed the calcination temperature effection on the photoreduction activity of Cu/TiO₂. When the calcination temperature was 500°C, the synthesized Cu/TiO₂ performed the highest photocatalytic activity.