Applied Mechanics and Materials Vol. 711

Abstract: The paper introduces a disaster tolerant system based on B/S mode and proposes a safe and effective communication protocol that combines with communicational needs. The protocol has been realized in this paper. This system has adopted remote management based on Web so that its construction is reasonable and operation is convenient. Through test,the system which is excellent in performance and stable in working is considered to be valuable for application and promotion.

Abstract: To improve compression performance, and realize the automatic selection of compression algorithms in processing images without the prior information, the regularity relationship between compression algorithms and image features is studied, and a preprocessing scheme of block and classification based on image features has been proposed in this paper. Compression algorithms pre and post preprocessing scheme are investigated for the same 100 images. Our scheme achieves the larger peak signal to noise ratio (PSNR), which demonstrates the effectiveness of the proposed preprocessing scheme of block and classification in improving compression performance and selecting suitable algorithm to process image without the prior information.

Abstract: Network security assessment is a complex multi-criteria problem including both quantitative and qualitative factors. In this paper, taken the computer network security evaluation index for a research object, the judgment matrix of index weight was improved based on the fuzzy theory, and a new weight determination approach was proposed to make up the shortcomings of traditional weight determination method and highlight the fuzziness of expert judgment. Meanwhile using fuzzy theory to establish fuzzy evaluation matrix, then combine analytic hierarchy process to set up a fuzzy AHP evaluation model of the computer network security. At the final stage, a security assessment of the system of an institution’s network was to implement to demonstrate the feasibility of the evaluation model.

Abstract: In viewing of information overload environment,traditional search engine has inherent insufficiency about retrieval accuracy and query mode,together with the characteristics of decision tree algorithm and knowledge push,this paper presets an intelligent knowledge push model,and discuss the mechanism of this model.The model strive to improve the retrieval efficiency and realize the intelligent service.

Abstract: Aiming at uncertainty and disturbance of the excitation system, we designed a kind of precise sliding mode controller with nonlinear disturbance observer that realized disturbance estimation and compensation. In order to obtain better convergence rates, based on the basis of fast terminal sliding mode surface, terminal piecewise sliding mode is adopted. Using the single machine infinite system, we have carried on the static and transient simulation. Simulation results show that control strategy adopted can guarantee system robustness to disturbance and has high control precision

Abstract: In this paper, by using Leggett-Williams fixed point theorem, we will study the existence of positive solutions for a class of multi-point boundary value problems of fractional differential equation on infinite interval.

Abstract: Removed due to plagiarism

Abstract: A compact and planar dual band antenna for Bluetooth and ultra-wideband (UWB) is presented. The antenna exhibits a dual band operation covering Bluetooth (2.4-2.484 GHz) and UWB (3.1-10.6 GHz) frequency bands. It is composed of a semi-circular and an L-shaped strip and fed by a microstrip line and built on a FR4 substrate with only 23 × 35 mm² surface area. Details of the antenna design and measured results are presented and discussed.

Abstract: A compact dual band-notched ultra-wideband (UWB) diversity antenna for multiple-input-multiple-output (MIMO) application is presented in this letter. The antenna consists of two tapered microstrip feeding lines and two semi-circle patches as the radiators. The C-band and wireless local area network (WLAN) for IEEE 802.11a band-notched function is achieved by etching four split-ring resonators (SRR) in the patches. The simulated and measured results show that the proposed antenna has a broadband impedance bandwidth covering the UWB band with definition of |S₁₁|<-10dB and a dual band-notched function at C-band and WLAN band. As a multiple-input antenna, a good isolation |S₂₁| between two ports better than -15 dB across the UWB is also achieved. The radiation patterns, peak gain, and envelope correlation coefficient are also measured and discussed.

Abstract: Fused Deposition Modeling is a widely used rapid prototyping technology; Filamentous molten materials are heated into fusion in heating cavity, and then squeezed out through the nozzle of sprinkler head. Under the control of the computer, the nozzle moves according to the information that CAD plane determined, extruding the molten materials and solidifying into parts at the same time. Almost any complex shape parts can be produced, and this technology has the advantage of high utilization of raw material and easy removal of support material.