Applied Mechanics and Materials Vol. 710

Abstract: This paper aims to identify significant control factors of particle swarm optimization (PSO) algorithms in solving permutation flowshop scheduling problems. Control factors of PSO algorithms considered herein include inertial weight, acceleration coefficients, breeding operation, and the amount of particles. The full factorial design method is applied to plan a set of experiments. Each experiment, denoting a specific version of PSO algorithm, is used to solve the test problems, Carlier problems. The searching ability of PSO algorithms is defined by the ratio of the number of times that the optimal makespan is searched to the total number of searching times. To identify significant factors, the analysis of variance (ANOVA) method is used to analyze the results of experiments. According to the results of ANOVA, adopting time-varying acceleration coefficients, breeding operation, and a low amount of particles can advance significantly the searching ability of PSO algorithms. Adopting a high amount of particles can increase significantly the robustness of PSO algorithms. Any two-factor interaction is not significant. Inertia weight is not a significant factor, so any effort to modify inertia weight is unnecessary.

Abstract: Speed and position controller respecting principles of energy optimal control for the drives with permanent magnet synchronous motor and time varying load torque are developed as a contribution to the energy saving and environmental protection. Two approaches to the energy saving controller design are analyzed and compared. The first one is strictly based on energy optimal control theory and derives analytical solutions of the control problem. The second approach for comparison presents approximated solution for the drive’s position controller when the optimal speed trajectory is modified to trapezoidal profile. Results are verified by simulation.

Abstract: Vehicle theft and vandalism is unfortunately an extremely common problem. As our world is modernizing, the ways of thefts are also changing and are becoming more and more sophisticated. Our project features an anti-theft system for wheels and rims. Moreover, the overheating and further bursting of the wheels has also been a major issue which has been worked over in this project.

Abstract: In order to measure the displacement and strain field in the fatigue crack tip area of CT specimens under high frequency resonant loading condition in the fatigue crack propagation test, a method based on the digital image correlation (DIC) and digital high-speed photography technology are proposed in this paper. First, a series of digital speckle images of CT specimen under sinusoidal alternating load were collected by digital high-speed photography equipment, the displacement and strain fields within the region of crack tip in each image were calculated by DIC. The sinusoidal changing strain curve has been obtained by the least square sine wave fitting method, and the characteristic parameters of sinusoidal strain are calculated, such as the amplitude, frequency, phase, mean load . The images of characteristic position in one stress cycle were obtained by comparing the fitted sine curve of strain with the corresponding speckle images. Finally, the dynamic strain gauge was used to measure the strain at crack tip point during one stress cycle, and the accuracy and feasibility of DIC method were verified by the experimental results. The study result presented in this paper will supply a foundation for exploring the crack propagation law and measuring the fatigue crack growth parameters under high frequency resonant loading condition further.

Abstract: The wave glider is composed of two parts: the float is roughly the size and shape of a surfboard that contains all the instrumentation needed for scientific experiments; the sub has wings and hangs 6 meters below on an umbilical tether. This difference allows wave energy to be harvested to produce forward thrust. According to the lake of design information and data for the wave glider, the main aim of the study is using computational fluid dynamics (CFD) to present a method to predict calm water resistance for the floating part of the wave glider (the hull). Wigley parabolic hull and high speed round bilge form (NPL) have been investigated in order to estimate the hydrodynamic performances of the hull using CFD software fluent. Wave glider is designed with slender hull shapes in order to decrease the wave making resistance of the ship.In this paper a method is evaluated by comparing the numerical predictions for wigley and NPL forms (2m) using the same mesh generation method under the same conditions to design the hull. Calculations for total calm water resistance are carried out using three different mesh sizes for Froude numbers in the range of 0.10 to 0.40 and compared for accuracy of the solution parameters. The close agreement between the numerical predictions shows the importance of CFD applications in estimating the hydrodynamics performance to design the floating hull and the numerical method is useful in glider design. This means that the method discussed in this paper can be used for the resistance calculation of some hulls like the float of the glider.

Abstract: The aim of this investigation is to optimize the multiple performancesof electrical discharge machining (EDM) process for SKH57 using grey relational analysis.Themachining performances namely electrode wear rate (EWR) and surface roughness (SR) were considered as theresponses. Aseries of experiments were conducted according to an L18 orthogonal array based on the Taguchi experimental design method.The main input variables such as machining polarity (P),peak current (I_p), auxiliary current with high voltage (I_H), pulse duration (_p), no-load voltage (V) and servo reference voltage (S_v) were selected to explore their effects on machining performances for high speed steel (HSS) graded SKH57.Moreover, analysis of variance (ANOVA) was conducted to explore the significant input variables crucially affecting the multiple performances. In addition, the optimal combinations of input variables were also determined from the response graph of grey relational grades. The experimental results confirmed the multiple performances of SKH57 would obviously be improved through optimizing the input variables using grey relational analysis.

Abstract: The centrifuge model test could achieve the stress state equal to that of the prototype in the ultra-acceleration field formed by the centrifuge machine. Then the similitude theory could be used to obtain the displacement of the prototype and development process of plastic zone, acquiring the mechanism of instability and failure of the full-scale prototype. Based on the review of a large number of literatures and materials on centrifuge technologies. This paper introduced an overview of the development history of centrifuge equipments, techniques and data acquisition, some ignore factors have been pointed out, as well as some key problems which need to be further researched.

Abstract: The energy output of the Sun is fairly constant, but the solar irradiance varies significantly from one place to another and changes throughout the year. Sunlight only reaches the parts of the Earth that are facing the Sun at any given time, and the most intense irradiance is experienced by those parts that are not at an angle to the Sun as it passes over. The modeling and simulation of solar irradiance for a given area is useful for planning future investments in PV and thermal collectors.

Abstract: With the increase of data dimension, many low dimensional mining algorithms cannot get satisfactory results. With the increase of data dimension, it can produce a large amount of redundant information; this information will greatly reduce the efficiency of mining, increasing the complexity of the mining algorithm. Feature selection is an efficient way to solve the problem; it can remove a lot of irrelevant and redundant features. In this paper, on the basis of Lars algorithm applying differential evolution thought to the extraction of feature subset, puts forward a new method of feature selection, DE - Lars algorithm. Experiments prove that DE - Lars algorithm enhances the precision of reducing dimension of space, effectively solve the problem of "Curse of Dimensionality ".

Abstract: In the mining of association rules, the generation of frequent itemsets is a key factor that influence the efficiency and performance of the algorithm. With the increase of data dimension, it is obvious that the traditional association rules mining algorithm can’t meet the demand of high dimensional data mining. On the basis of Apriori algorithm, we put forward Split Mtrix _Apriori algorithm in this paper. By generating the Boolean matrix of the database, Split Mtrix _Apriori algorithm decreased the times of scanning database when generating the frequent itemsets. With adopting grouping processing strategy in the Boolean matrix, the algorithm can still keep high efficiency in dealing with high-dimensional data.So Split Mtrix _Apriori improved the efficiency of association rule mining significantly.