Applied Mechanics and Materials Vols. 55-57

Abstract: Radar systems are used by air defense forces to detect and track aircraft. Route planning attempts to enhance safety by minimizing the exposure of the aircraft to the threat air defense systems while achieving the mission objectives. Based on Voronoi diagram theory, a flight route optimization method is introduced to insure the armed helicopter to penetrate the emery’s radar defense system at the lowest danger. The factors, such as radar cross section and distance between helicopter and radar, that affect the radar detection are firstly analyzed. Then Voronoi diagram and its application for route planning to minimize the detection probability of an armed helicopter are described introduced in details. Dijkstra algorithm is employed to solve the optimization problem and to obtain the initial flight path. The simulation of artificial potential field dynamic is performed to transform the initial path to the smooth flight route. Example analysis of a hypothesis armed helicopter shows that the developed method is helpful for the on-the-spot planning that combines aircraft flight performance and intelligence information regarding the estimated enemy weapon locations to develop routes that avoid or mask the enemy sensor and weapon envelopes.

Abstract: The effects of several factors, including fuel mixing ratio fed into boiler, bed temperature, primary air ratio, on burnout characteristics of mixed fuel of petroleum coke and oil shale were investigated at a 1 MW circulating fluidized bed (CFB) test apparatus at Xi’an Thermal Engineering Research Institute. Meantime, the effect of the fuel mixing ratio and Ca/S molar ratio on SO₂ emission during co-combustion of petroleum coke and oil shale were studied. The results show that preferred mixing ratio of petroleum coke over oil shale is between 4:6 and 5:5, and primary air ratio is about 55% to accomplish favorable burnout of the mixed fuel. The combustion efficiency is higher than 97%. The increase in oil shale share in the mixture helps to improve the desulfurization efficiency during co-combustion. There is an optimum Ca/S molar ratio to achieve the highest desulfurization efficiency for co-firing the petroleum coke and oil shale. SO₂ emission during co-combustion of petroleum coke and oil shale can meet the environmental requirement.

Abstract: In this thesis, polystyrene nanomembranes made by electrospinning technique were utilized to deal with Cu²⁺(5mg/l), Cr⁶⁺(5mg/l) and methylene blue (10mg/l) contained in simulated dyeing wastewater. Polystyrene liquor (8% (m/m), dissolved in chloroform) was electrospun and processed nanofibrous membrane; the nanofiber diameter was 250nm~15µm; the detected pore size was 3nm~0.5µm and the membrane thickness was 170µm. A plate membrane system was used to test nanofiltration characteristics of pollutants (Cu²⁺, Cr⁶⁺ and methylene blue). The experiment showed that the interception rates were above 91%, and the water flux was about 5.8-15.4ml/ (cm²h).

Abstract: The energy utilization is crucial for electric or hybrid vehicles to solve the problem of braking energy recovery, especially of low speed energy recovery. In this paper, the energy transform model of electric vehicle in braking state is analyzed, and the half bridge control main circuit was selected. The energy recovery strategies and methods on the breaking process of low speed were researched. The concrete realization of parameters decision and system control was given. The results show that the energy recovery strategy and electric vehicle model can improve the energy transform efficiency in low speed state.

Abstract: With the rapid development of tourism in“3+5” urban agglomeration, more and more attention is paid to ecological security triggered by tourism wave. Taking Loudi City in urban agglomeration as an example, conduct empirical study on the application of ecological footprint theories and methods on the quantitative evaluation of sustainable development of regional tourism. The results show: tourism ecological footprint per capita of Loudi was 768.9881×10^-5hm² in 2009 in which transportation taking 55.3156% is the maximum, and food consumption taking 39.7622% is the second one. Tourism ecological capacity per capita was 1520.5170×10^-5hm²; tourism ecological surplus per capita was 751.5289×10^-5hm² and ecological security degree was 0.5057 which showed a common condition or could be said as a safer condition. However, with the rapid development of tourism, tourism ecological footprint of Loudi City shows an increasing trend year by year. We should coordinate well the relationship between tourism development and ecological environmental protection.

Abstract: The purpose of this paper is to introduce a general scenario for Enterprise SNS knowledge community of E-Learning to promote knowledge innovation, including four sub processes and two knowledge techniques. First, four sub processes are researched respectively, including: motivation to acquire new knowledge, knowledge searching and collection, knowledge decision-making and knowledge innovation. Second, knowledge base and recommendation are two knowledge techniques. The paper underscores the significance of E-Learning to improve knowledge innovation in enterprise and a case study is given.

Abstract: This study is a productivity review on the literature gleaned from SSCI, SCIE databases concerning trust analysis in social network community research. The result indicates that the number of literature productions on trust analysis in social network community is still growing. The main research development country is the United States, and from the analysis of the distribution of language, English is the most popular language. Moreover the research focuses on are mainly empirical research, computational model and recommendation system, we analyze these typical references in detail, also limitations and future research.

Abstract: Polypropylene(PP)/clay nanocomposites were prepared by solution blending. The microstructure of PP/clay nanocomposites was studied by wide-angle X-ray diffraction (XRD) analysis. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to investigate thermal properties of PP/clay nanocomposites. XRD pattern prove that clay layers were exfoliated into nanometer size in PP matrix and that α-Phase crystallite was the main crystallite of PP in PP/clay nanocomposites. TGA examinations confirmed that the maximum decomposition temperature of PP/clay nanocomposites was higher than that of neat PP and that the thermal stability of PP/clay nanocomposites rose noticeably. Results of DSC scans showed the crystalliztion temperature of nanocomposites was slightly bigger than that of pure PP due to the efficient nucleating effects of clay layers.

Abstract: Clay was organically modified with one kind of ionic liquild. Organical clay obtained was used to prepare poly(propylene) (PP)/clay nanocomposites by solution blending. Flourier transform infrared (FTIR), wide-angle X-ray diffraction (XRD) and thermogravimetric analysis (TGA) revealed that the ionic liquild was loaded in the galleries of organically modified clay. TGA result show the thermal stability of organically modified clay was superior to clay. XRD patterns indicated that the d-spacing of clay layers increased to 2.96 nm from 1.22 nm of clay. XRD patterns of PP/clay nanocomposites show that clay layers were dispersed in PP matrix by nanometer size.

Abstract: In this paper, an approach based on wavelet packet analysis is proposed to deal with the problem that acoustic signal of moving vehicle is easily influenced by environmental noise in vehicle type classification. Wavelet packet analysis is applied to extract local and detail feature information of acoustic signal in the time-frequency domain. Firstly, raw acoustic signal is decomposed into different frequency bands by wavelet packet analysis, and then decomposition coefficients are reconstructed. The energy of every frequency band component is used to form the feature vector. Finally, vehicle type classification is implemented by RBF neural network on the basis of these feature vectors. Experimental results show that the proposed method is feasible and effective.