International Journal of Modeling, Simulation, and Scientific Computing

In this paper, a physical model of coal roadway which is clamped by upper and lower soft rock with extra thickness was built according to the characteristics of soft rock strata in china's western mining area. Then, a series of orthogonal numerical experiments were carried out by selecting the strength and stiffness parameters of soft rock and coal seam as well as the in situ stress of soft rock strata as experimental factors and roadway displacements (convergence displacements of sides, displacement of roof to floor) as experimental indexes. By constructing the F statistics with different inspection levels, evaluation method for influence of the experimental factors on stability indexes were defined. Thus, influence degrees of specified parameters on the stability of roadway were divided into five classes as follows: highly significant influence, significant influence, relatively significant influence, little significant influence, and no influence respectively which realize the quantitative analysis of the influence degrees of experimental factors. The finite element calculation results showed that main failure mode of coal roadway that usually showed as tension failure of coal seam in roof and deformation factors of coal seam had the most remarkable effect on roadway displacements. The conclusions provide theoretical basis for further analysis of the mechanism of "roof burst" in roadway maintenance.

Lattice Boltzmann method (LBM) is a new attractive computational approach for simulating isothermal multi-phase flows in computational fluid dynamics (CFD). It is based on the kinetic theory and easy to be parallelized. This study aims to analyze the performance of parallel LBM programming for the incompressible two-phase flows at high density and viscosity ratio. For this purpose, a liquid drop impact on a wetted wall with a pre-existing thin film of the same liquid is simulated by using the parallel LBM code. During the simulations, the domain decomposition, data communication and parallelization of the LBM code using the message passing interface (MPI) library have been investigated. The computational results show that the parallel LBM code exhibits a good high performance computing (HPC) on the parallel speed-up.

We discuss a novel use of the Geant4 simulation toolkit to model molecular transport in a vacuum environment, in the molecular flow regime. The Geant4 toolkit was originally developed by the high energy physics community to simulate the interactions of elementary particles within complex detector systems. Here its capabilities are utilized to model molecular vacuum transport in geometries where other techniques are impractical. The techniques are verified with an application representing a simple vacuum geometry that has been studied previously both analytically and by basic Monte Carlo simulation. We discuss the use of an application with a very complicated geometry, that of the Large Synoptic Survey Telescope camera cryostat, to determine probabilities of transport of contaminant molecules to optical surfaces where control of contamination is crucial.

We develop an efficiently improved knowledge-based neural network (KBNN) associated with optimization algorithms and finite element analysis (FEA) to accurately predict spring-back angles in metal sheet bending. The well-known V and U prevalent processes of bending are considered. The KBNN predictive results are based on the empirical model and artificial neural network (ANN) modeling. The empirical model is constructed from the FEA results using response surface method, while the multilayer perceptron is employed to create the ANN. The trained KBNN can accurately model the relationship between the spring-back angles and process parameters. The obtained results are validated against other existing methods showing a high accuracy.

Dendritic spine plays an important role in calcium regulation in a neuron cell. It serves as a storage site for synaptic strength and receives input from a single synapse of axon. In order to understand the calcium dynamics in a neuron cell, it is crucial to understand the calcium dynamics in dendritic spines. In this paper, an attempt has been made to study the calcium dynamics due to the exogenous buffers, in dendritic spines with the help of a sectional model. The compartments of dendritic spines are discretized using triangular elements. Appropriate boundary conditions have been framed. Finite element method has been employed to obtain the solution in the region for a two-dimensional unsteady state case. MATLAB 7.11 is used for simulation of the problem and numerical computations. The numerical results have been used to study the effect of exogenous buffers on calcium distribution in dendritic spines.

Choosing the best way for describing physical reality has always been standing in focus of research. Several methodologies have been developed based on classical mathematics, or statistics and also new disciplines — such as soft-computing techniques — appeared. Petri Nets as one of the most naturalistic modeling methodologies are well suited to describe complex process in general. However in some fields of modeling the describing power of basic Petri Nets proved not to be robust enough, therefore several extensions were made to the original concept. Colored tokens (Colored Petri Nets), stochastic delayed streaming of mobile entities (Stochastic Petri Nets), object oriented architecture (Object Oriented Petri Nets), numerical (Numerical Petri Nets) and linguistic attributes (Fuzzy Petri Nets) broaden the range of capabilities. In some fields of problem solving, usage of static and mobile knowledge bases is needed: e.g., flexible manufacturing systems, or intelligent traffic simulation. These problems to be investigated involved new conceptual developments of Petri Nets and led to the introduction of Knowledge Attributed Petri Nets. At the same time distributed control in simulation appeared, intelligent agents supported the connection of mobile knowledge bases and static inference engines in an effective way. The mentioned extensions brought general support in model synthesis, but some unsolved questions remained related to the implementation of intelligent mobile entities. This paper highlights a new level of AI controlled simulation introducing the Extended Knowledge Attributed Petri Nets that offer the capability of easy implementation of mobile inference engines and knowledge base, providing general mobile AI in Petri Nets.

In this article, we discuss a new smart alternating group explicit method based on off-step discretization for the solution of time dependent viscous Burgers' equation in rectangular coordinates. The convergence analysis for the new iteration method is discussed in details. We compared the results of Burgers' equation obtained by using the proposed iterative method with the results obtained by other iterative methods to demonstrate computationally the efficiency of the proposed method.

Textile industry is very important to the development of Chinese industry and economy. Image processing techniques are beneficial to improve the quality of cotton goods. Suitable blending ratio of yarn is good for it. It is significant to measure the blending ratio of yarn in the practice of textile engineering. Combined with results done by other scholars, this paper uses the concepts of acreage index, abnormity index and fluctuation index. Based on these morphologic indices, it is convenient to construct corresponding eigenvector and to discuss useful mathematical method for the cluster analysis during the measurement of the blending ratio. This paper also sets up some kinds of nonlinear optimization model for the problem. Using classical integer programming algorithm, support vector machine algorithm and genetic algorithm to the problem, we get fine results for cluster analysis. Finally, we give out another problem of image processing and have some discussions about it.

This paper is concerned with deriving a dynamic model of a moderately flexible needle inserted into soft tissue, where the model's output is the needle deflection. The main advantages of the proposed dynamic modeling approach are that the presented model structure involves parameters that are all measurable or identifiable by simple experiments and that it considers the same inputs that are currently used in the clinical practice of manual needle insertion. Conventional manual needle insertion suffers from the fact that flexible needles bend during insertion and their trajectories often vary from those planned, resulting in positioning errors. Enhancement of needle insertion accuracy via robot-assisted needle steering has received significant attention in the past decade. A common assumption in previous research has been that the needle behavior during insertion can be adequately described by static models relating the needle's forces and torques to its deflection. For closed-loop control purposes, however, a dynamic model of the flexible needle in soft tissue is desired. In this paper, we propose a Lagrangian-based dynamic model for the coupled needle/tissue system, and analyze the response of the dynamic system. Steerability (controllability) analysis is also performed, which is only possible with a dynamic model. The proposed dynamic model can serve as a cornerstone of future research into designing dynamics-based control strategies for closed-loop needle steering in soft tissue aimed at minimizing position error.

A brief review of the importance of simulation-based engineering and science (including social sciences) is followed by a historic perspective of model-based simulation. Section 2 is on declarative modeling of component systems as well as its advantages for self-documentation and for computer-aided checks and coupling. As an example for declarative modeling, General System Theory (GEST) implementor is given. In Sec. 3, basic concepts for coupling of component models, and rules for computer-assisted coupling specification are explained. Section 4 is devoted to possible computerized checks in couplings of declarative models such as: (1) automatic unit checking to avoid meaningless input/output matching at the time of coupling specification, (2) automatic threshold checking to provide warnings and/or to avoid disasters, and (3) automatic unit conversion for convenience of using library models. Section 5 is about several layers of nested couplings for modeling systems of systems. In Sec. 6, two types of variable couplings are discussed: (1) couplings with variable connections (to allow input/output relations of models to depend on time or state conditions) and (2) coupling with variable component models (to allow component (or coupled) models to be switched based on time or state conditions). Section 7 is on the use of multimodels as component models in couplings. Section 8 is on types of inputs and their use in couplings as well as on external inputs to simulation studies. In Sec. 9, conclusions and future work for complex systems are outlined. Especially, the values of simulation systems engineering as well as understanding and avoidance of misunderstanding in cognitive and emotive simulations are stressed. Appendix A is a list of almost 50 types of couplings and Appendix B lists over 50 terms related with couplings in modeling and simulation. To show the richness of "input" concept which is important in specification of input/output relations of component models, Appendix C lists almost 150 types of inputs. Information shared in this article may be useful in developing advanced modeling and simulation software, tools and environments.

Wireless ad hoc network is generally employed in military and emergencies due to its flexibility and easy-to-use. It is suitable for military wireless network that has the characteristics of mobility and works effectively under severe environment and electromagnetic interfering conditions. However, military network cannot benefit from existing routing protocol directly; there exists quite many features which are only typical for military network. For example, there are several radios in the same vehicle. This paper presents a new metric for routing, which is employed in A* algorithm. The goal of the metric is to choose a route of less distance and less transmission delay between a source and a destination. Our metric is a function of the distance between the ends and the bandwidth over the link. Moreover, we take frequency selection into account since a node can work on multi-frequencies. This paper proposed the new metric, and experimented it based on A* algorithm. The simulation results show that this metric can find the optimal route which has less transmission delay compared to the shortest path routing.