Applied Mechanics and Materials Vols. 20-23

Abstract: At present, the usual image definition evaluation methods are poor in focusing precision and have a lot of calculations. In view of these problems, the paper analyzed the factors affecting an image quality evaluation, and proposed two evaluation models based on an image contrast change rate and an autocorrelation function. These methods avoided efficiently the phenomenon of partial peaks of focusing-function curves for noise disturbing. The stimulant test proves that the focusing curve of the evaluation model in the paper has many advantages, such as good focusing performance, strong antijamming ability, good real time and so on.

Abstract: The crosstalk fault in VLSI circuits is one of the interference effects being caused by parasitic capacitance and inductance coupling, it can lead to functional errors of circuits. It is necessary to detect the crosstalk faults in order to insure the functions of circuits. A new test method for crosstalk faults in VLSI circuits based on multiple-valued decision diagrams is presented in this paper, the test vectors of crosstalk faults are generated by building a multiple-valued decision diagram that is a difference operation of the two multiple-valued decision diagrams corresponding to the normal circuit and faulty circuit, respectively. One advantage of the test method is that it can get all test vectors of a given crosstalk fault, therefore for a digital circuit, the test set with minimal number of test vectors can be obtained. Experimental results on a lot of digital circuits demonstrate the feasibility of the method proposed in this paper.

Abstract: The more signal path ways close to each other in digital circuits, the greater the coupling effects. The coupling effects can led to an increasing number of signal integrity related faults such as crosstalk faults. In this paper, the glitch faults of crosstalk effects are studied. First of all, the test vector generation using signal paths of circuits is given. Secondly, a new test method for crosstalk faults in digital circuits is presented, which is based on the genetic algorithm with niche. The test method can detect the maximal crosstalk effects, i.e. the test vectors to be produced is to switch a set of aggressors that maximizes the switching of total coupling effects. The test method is also used to produce the test vectors of multiple crosstalk faults. The experimental results show that the method proposed in this paper can get the test vectors of the multiple crosstalk faults if the faults are testable.

Abstract: Given m databases D1,...,Dm of strings, the purpose of the frequent string mining is to find all strings that fulfill certain constraints of all string databases. In this paper, a useful data structure is proposed to construct suffix and LCP table which can reduce the total space consumption of string mining efficiently. We demonstrate the use of this data structure by optimizing the algorithm proposed by A.Kügel et al [7] and present the improved algorithm. It is achieved that the space consumption in our algorithm is proportional to the length of the largest string of all databases. A set of comprehensive performance experiments shows that the processing rate is enhanced because amount of items are reduced in new data structure.

Abstract: The hyper-chaotic Newton downhill method finding all real solutions of nonlinear equations was proposed and the forward displacement analysis on the 33th non-plane 2-coupled–degree nine-link Barranov truss was completed. Four constrained equations were established by vector method with complex numbers according to four loops of the mechanism and four supplement equations were also established by increasing four variables and the relation of sine and cosine function. The established eight equations are that of forward displacement analysis of the mechanism. Combining Newton downhill method with hyper-chaotic sequences, hyper-chaotic Newton-downhill method based on utilizing hyper-chaotic discrete system to obtain locate initial points to find all real solutions of the nonlinear questions was proposed. The numerical example was given. Comparison was also done with other finding solution method. The result shows that all real solutions have been quickly obtained, and it proves the correctness and validity of the proposed method.

Abstract: In order to evaluate the supply chain risks, proposed the combination method based on Vague Sets and fuzzy risk assessment, and took an application model for example. First introduced the basic knowledge about fuzzy mathematics and Vague sets. Then gave the model of risk assessment and its algorithms, determined the major risk factors using Vague set theory and fuzzy mathematics method, combined the expert evaluation and fuzzy switch, applied the fuzzy analysis method to the static risk assessment of suppliers’ risks and the individual risk status assessment of special event. Finally, described the specific flow by an example.

Abstract: Many questions in natural science and engineering are transformed into nonlinear equations to be found. Newton iterative method is an important technique to one dimensional and multidimensional variables and iterative process exhibits sensitive dependence on initial guess point. The probability characteristic of hyper-chaotic sequences produced by two dimensional hyper-chaotic discrete systems was analyzed. For the first time, a new method to find all solutions based on utilizing　two dimensional probability hyper-chaotic discrete mapping to obtain initial points to find all solutions of the nonlinear questions was proposed. The numerical examples in linkage synthesis and approximate synthesis show that the method is correct and effective.

Abstract: The discovery of dynamical chaos is one of the main achievements in the modern science and how to expand its application has important significance to the development of modern science. Many questions in natural science and engineering are transformed into nonlinear equations to be found. Newton iterative method is an important technique to one dimensional and multidimensional variables and iterative process exhibits sensitive dependence on initial guess point. To improve solving efficiency, the demand to chaos sequences is uniform distribution in every interval. The probability characteristics of three kinds of chaos were investigated. The simulations were work out with Matlab software. For the first time, a new　method to find all solutions based on utilizing　equal probability chaos sequences to obtain initial points to find all solutions of the nonlinear questions was proposed　and it has higher solving efficiency compared with unequal probability chaos sequences to find all solutions. The numerical example in linkage synthesis shows that the method is correct and effective. And, different equal probability chaos sequences has different solving efficiency, so, for the same kind of question to be solved we can find the best equal probability chaos sequences to be used. This provides a simple realization method for mechanics design.

Abstract: Existing methods for recognizing polygons can be improved. A new concept “homograph” and then a new method for recognizing polygons based on the principle of homograph are proposed. First six topological characteristics and geometrical characteristics are introduced that are invariant to describe polygon under affine transformation. Then, the new concept of homograph is defined in terms of six topological characteristics and geometrical characteristics. Based on of this definition, a new algorithm is proposed for recognizing that two polygons are homograph. The topological structure is introduced to analyze homograph qualitatively, the algorithm is insensitive to noises; and the geometrical structure is introduced to analyze homograph quantitatively, thus the algorithms can show tiny differences between polygons. It can not only recognize objects with different shape but also distinguish between objects with the same shape but with different sizes and scales. Comparing with other recognition algorithms, the algorithm presented showed apparent improvement. The effectiveness of the algorithm is demonstrated by experiments.

Abstract: Fault tolerance is crucial to the operating safety and performance of train locating system. Based on the requirements of reliability and safety for train locating, the fault characteristics of location measuring sensors are analyzed. Based on the structure of the train locating system, the fault-tolerant design of the system is given with the location filtering module for case, in which six fault detectors are employed to determine the configuration of the module. Then a PCA based fault detection and isolation method is proposed with Hawkins T2 statistics and the corresponding control limit. By dynamically adjusting the efficiency factors, fault could be detected and isolated as prior defined isolating strategies, and then the fault tolerant performance will be guaranteed. Simulation results demonstrate the high fault tolerant ability of the proposed approach and certain practical application value.