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71.
Hung Son Nguyen 《Theoretical computer science》2011,412(42):5816-5819
72.
Manufacturing facilities are expected to maintain a high level of production and at the same time, employ strict safety standards to ensure the safe evacuation of the people in the event of emergencies (fire is considered in this paper). These two goals are often conflicting. This paper presents a methodology to evaluate evacuation safety versus productivity concurrently for various, widely known manufacturing layouts. While the safety performance indicators such as evacuation times are inferred from the crowd (agent based) simulation, the productivity performance indicators (e.g. throughput) are analyzed using the discrete event simulation. To this end, this research focuses on creating innovative techniques for developing accurate crowd simulations, where Belief-Desire-Intention (BDI) agent framework is employed to build each person’s individual actions and the interactions between them. The data model and rule based action algorithms for each agent are reverse-engineered from the human-in-the-loop experiments in the immersive virtual reality environments. Finally, experiments are conducted using the constructed simulations to compare safety and productivity for different layouts. To demonstrate the proposed methodology, an automotive power-train (engine and transmission) manufacturing plant was used. Initial results look quite promising. 相似文献
73.
This paper presents a practical advanced analysis software which can be used for nonlinear inelastic analysis of space steel structures. The software employs the stability functions and the refined plastic hinge model to minimize modeling and computational time. The generalized displacement control method is adopted to solve the nonlinear equilibrium equations. This algorithm can accurately trace the equilibrium path of the nonlinear problem with multiple limit points and snap-back points. A user-friendly graphic interface of the software is developed to facilitate the modeling process and result interpretation of the problem. Several numerical examples are presented to verify the accuracy and computational efficiency of the proposed software by comparing the results predicted by the present software with those given by the ABAQUS and other available results. 相似文献
74.
Son Nguyen-Hoang Phuc Phung-Van Sundararajan Natarajan Hyun-Gyu Kim 《Engineering with Computers》2016,32(2):267-284
In this paper, a combined scheme of edge-based smoothed finite element method (ES-FEM) and node-based smoothed finite element method (NS-FEM) for triangular Reissner–Mindlin flat shells is developed to improve the accuracy of numerical results. The present method, named edge/node-based S-FEM (ENS-FEM), uses a gradient smoothing technique over smoothing domains based on a combination of ES-FEM and NS-FEM. A discrete shear gap technique is incorporated into ENS-FEM to avoid shear-locking phenomenon in Reissner–Mindlin flat shell elements. For all practical purpose, we propose an average combination (aENS-FEM) of ES-FEM and NS-FEM for shell structural problems. We compare numerical results obtained using aENS-FEM with other existing methods in the literature to show the effectiveness of the present method. 相似文献
75.
76.
Geo-demographic analysis is an essential part of a geographical information system (GIS) for predicting people’s behavior based on statistical models and their residential location. Fuzzy Geographically Weighted Clustering (FGWC) serves as one of the most efficient algorithms in geo-demographic analysis. Despite being an effective algorithm, FGWC is sensitive to initialize when the random selection of cluster centers makes the iterative process falling into the local optimal solution easily. Artificial Bee Colony (ABC), one of the most popular meta-heuristic algorithms, can be regarded as the tool to achieve global optimization solutions. This research aims to propose a novel geo-demographic analysis algorithm that integrates FGWC to the optimization scheme of ABC for improving geo-demographic clustering accuracy. Experimental results on various datasets show that the clustering quality of the proposed algorithm called FGWC-ABC is better than those of other relevant methods. The proposed algorithm is also applied to a decision-making application for analyzing crime behavior problem in the population using the US communities and crime dataset. It provides fuzzy rules to determine the violent crime rate in terms of linguistic labels from socioeconomic variables. These results are significant to make predictions of further US violent crime rate and to facilitate appropriate decisions on prevention such the situations in the future. 相似文献
77.
This paper is concerned with the robust control problem of linear fractional representation (LFT) uncertain systems depending on a time-varying parameter uncertainty. Our main result exploits a linear matrix inequality (LMI) characterization involving scalings and Lyapunov variables subject to an additional essentially nonconvex algebraic constraint. The nonconvexity enters the problem in the form of a rank deficiency condition or matrix inverse relation on the scalings only. It is shown that such problems, but also more generally rank inequalities and bilinear constraints, can be formulated as the minimization of a concave functional subject to LMI constraints. First of all, a local Frank and Wolfe (1956) feasible direction algorithm is introduced in this context to tackle this hard optimization problem. Exploiting the attractive concavity structure of the problem, several efficient global concave programming methods are then introduced and combined with the local feasible direction method to secure and certify global optimality of the solutions. Computational experiments indicate the viability of our algorithms, and in the worst case, they require the solution of a few LMI programs 相似文献
78.
This paper proposes an adaptive robust fuzzy control scheme for path tracking of a wheeled mobile robot with uncertainties.
The robot dynamics including the actuator dynamics is considered in this work. The presented controller is composed of a fuzzy
basis function network (FBFN) to approximate an unknown nonlinear function of the robot complete dynamics, an adaptive robust
input to overcome the uncertainties, and a stabilizing control input. The stability and the convergence of the tracking errors
are guaranteed using the Lyapunov stability theory. When the controller is designed, the different parameters for two actuator
models in the dynamic equation are taken into account. The proposed control scheme does not require the accurate parameter
values for the actuator parameters as well as the robot parameters. The validity and robustness of the proposed control scheme
are demonstrated through computer simulations.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
79.
Son S.H. Mukkamala R. David R. 《Knowledge and Data Engineering, IEEE Transactions on》2000,12(6):865-879
Database systems for real-time applications must satisfy timing constraints associated with transactions in addition to maintaining data consistency. In addition to real-time requirements, security is usually required in many applications. Multi-level security requirements introduce a new dimension to transaction processing in real-time database systems. In this paper, we argue that, due to the conflicting goals of each requirement, tradeoffs need to be made between security and timeliness. We first define mutual information, a measure of the degree to which security is being satisfied by a system. A secure two-phase locking protocol is then described and a scheme is proposed to allow partial violations of security for improved timeliness. Analytical expressions for the mutual information of the resultant covert channel are derived, and a feedback control scheme is proposed that does not allow the mutual information to exceed a specified upper bound. Results showing the efficacy of the scheme obtained through simulation experiments are also discussed 相似文献
80.
Effect of NaOH on the decomposition of halogenated hydrocarbon by supercritical water oxidation 总被引:1,自引:0,他引:1
Sang-Ha Son Jong-Hwa Kim Hyeon-Chul Lee Chang-Ha Lee 《Korean Journal of Chemical Engineering》2006,23(3):385-390
To protect alloys from corrosion phenomena in the supercritical water oxidation (SCWO) process, the effects of neutralizer
on the conversion and corrosion were investigated. The surface morphologies of all the alloy coupons exposed to 2,4-Dichlorophenol
(2,4-DCP) in the SCWO were significantly changed in microscopic images. The theoretical amount of NaOH as a neutralizer was
calculated under the assumption of complete oxidation of 2,4-DCP. The pre-dosed NaOH in the range of 100% to 300% stoichiometric
amount could not affect significantly the pH value in the SCWO. Moreover, the pH = 7 was not achieved until 700% stoichiometric
amount of NaOH was pre-dosed to the reactor. It is noted that the conversion rate recorded over 99% without oxidant when 800%
of NaOH was pre-dosed into the reactor. In addition, under the addition of H2O2 as an oxidant, the increased amount of NaOH led to the improvement of conversion rate. The pre-dosed NaOH may contribute
to the conversion rate of 2,4-DCP in the SCWO. However, due to low solubility of salt in the SCWO, the fouling problem should
be solved in the SCWO process. 相似文献