Papers by Keyword: Random

Abstract: Research on composites reinforced with abaca fiber is still being carried out. Research about fiber treatment, research about mixing abaca fiber with other natural fibers, or mixing abaca fiber with synthetic fiber, as well as the types of matrices used and research on differences in fiber orientation to determine its strength still being conducted. This research aims to study the mechanical properties of abaca fiber orientation on abaca fiber reinforced composite. The fiber is abaca fiber (Musa Textiles Ne) and the matrix is epoxy resin. The abaca fiber is first soaked in alkaline NaOH solution with a ratio of 5wt % to water for 2 hours. After being washed thoroughly and dried, the abaca fiber is prepared in 3 orientations, the first is woven orientation, the second is unidirectional orientation and the last is random orientation, where the fiber were cut into 20 mm pieces and arranged randomly. The abaca fiber is then mixed with epoxy resin in a ratio of 40% abaca fiber and 60% epoxy resin and pressed to a thickness of 4 mm. According to ASTM D638 standard, tensile strength testing was conducted and flexural strength was conducted according to ASTM D790 standard. The results show that the tensile strength of woven orientation is 63.1156 MPa and fiber with a unidirectional orientation is 62.4829 MPa and fiber with a random orientation is 22.3517 MPa. The elastic modulus of woven, unidirectional and random orientations are 3.6425GPa, 3.9734 GPa, and 1.6449 GPa, respectively. Bending test results show that random orientation is more flexible than woven and unidirectional orientation, where the strain value is 0.0408 mm/mm, 0.0393 mm/mm, and 0.0369 mm/mm, respectively. The flexural modulus of the three different orientations is 0.8082 GPa for random orientation, 1.2176 GPa for woven orientation and 1.675 GPa for unidirectional orientation. It can be concluded that the tensile strength of woven orientation increases by 1% to unidirectional orientation and 182% to random orientation. Compared to the three different orientations, random orientation has higher bending properties than woven and unidirectional orientation, and woven orientation is still more flexible than unidirectional orientation.

Abstract: In this paper, an original method is presented for evaluating the probability of failure in a precise manner in the tube hydroforming process (THP). This process consists to apply an inner pressure combined to an axial displacement to manufacture the part. During the manufacturing phase, inappropriate choice of the load paths can lead to failure. Our approach is to determine the space failure probability for each item in the area is critical. It is defined by identifying the critical element, and then a patch is defined on this item that represents the area of the most probable failure. The identification of the critical element for each failure mode is done by reference the state of strain on the forming limit curve (FLC) of the material. Access to the probability of space failure allows to give an idea on the stability of the process and also to predict the most likely area where plastic instability can appear. The failure probability estimation based on a characterization probabilistic principal strains (major and minor) for each failure mode and for each element. Access to this probability of failure in a direct manner is impossible given the complexity of the treated problem and the huge number of calculations by finite elements necessary. To compensate for this problem, approximation techniques have been used to replace the real model by metamodel that enables to evaluate the response quickly and allows us to get an idea on the stability of the process.Keywords: Hydroforming process, metamodels, random, forming limit curve (FLC), failure mode, finite element.

Abstract: According to the all set theory, a fuzzy-random creep fracture model was presented in this work. To deal with the function, the following steps were taken. First, the steady state creep coefficient (A) and steady state creep exponent (n) were considered in the fuzzy-random variables, then the C*-integral was considered in a fuzzy-random variable. Finally, with the interval analysis, the result of the fuzzy-random creep fracture model was given.

Abstract: Because uncertainty and complexity of the athlete’s injury risk factors, the general risk method can’t reflect the risk of athletes. Based on Bayesian probability estimation method, this paper proposes a new evaluation system of athlete injury risk. Combined with the VB programming and visualization display function, it realizes visual evaluation function of athlete injury risk, and the injury level of athletes is divided into three warning levels. Finally through risk assessment system, we get the effect curve of athletes training number and training time on the injury. From the results we can conclude that the training time has a certain randomness injury to the athletes, and training times are decisive factors to some injury of athletes. It provides technical reference and data support for the risk assessment of injury.

Abstract: Based on the Sobol’ theory, Hamma and Saltelli indicator system, the path parameters were divided into the different subsets for the vibration transfer path systems with random paths in this paper. The object function was constructed and decomposed, thus the global sensitivity based on variances was formed. The first-order and total sensitivities of various parameter subsets were calculated using Monte-Carlo simulation method combined with Latin hypercube sampling technique. Through the analysis example, the way is feasible to analyze the interaction of paths or path parameters in the vibration transfer path systems with uncertainty.

Abstract: Three kinds of dimensional simplified models were established according to the structure properties of interpenetrating network composites. The cutting process of INC with different structure parameters were calculated by finite element method. The random properties of cutting forces were also analyzed. It is shown that cutting forces would increase when reinforced phase is cut. Micro cracks are liable to be caused on interfaces between two phases. The structure parameters d、α、β have great effects on cutting forces and cause random fluctuation which cause random properties for INC cutting process.

Abstract: Network utility maximization model with random link failures was presented in this paper. We provide a distributed algorithm based on the dual decomposition and investigate the impacts of link failures on the network utility. Numerical results validated the convergence of the proposed algorithm and our conclusions.

Abstract: Network coding has recently been widely applied in various distributed systems for throughput improvement and/or resilience to network dynamics. However, the computational overhead introduced by network coding operations is not negligible and has become the obstacle for practical deployment of network coding. In this paper, I exploit the computing power of commodity many-core Graphic Processing Units (GPUs) and multi-core CPUs to accelerate the network coding computation. With the implementation of the algorithms, significant encoding and decoding throughput can be achieved.

Abstract: Economic lot and scheduling problem is one of the focuses in the international engineering field. Aiming at several kinds of products and sets of production lines, this paper introduces a production model, which is based on the principles of artificial intelligence and introduces random factors as time changes, such as market demand and production line equipment. Besides, this paper puts forward a dynamic heuristic search production schedule method, and the simulation results show that the effectiveness and predictability of this method.

Abstract: Based on rigid-flexible coupling dynamic model, firing density model and ADAMS / Insight platform, the chamber pressure random of machine gun RCWS is studied by stochastic dynamics simulation of stochastic chamber pressure curve generated by the Monte-Carlo random generator and the internal ballistics module. It can provide theoretical guidance to the virtual fire accuracy of the machine gun RCWS.