38 research outputs found

    Preventive replacement for belligerent systems

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    A mortar is commonly used as an indirect firing weapon to support close fires with a variety of ammunition. There are mortar weapons with various shells. Each type of shells fired by mortars does damage to a weapon when the total damage on a mortar weapon reaches the tolerance limit, the mortar weapon either fails or explodes, leading to a compulsory replacement which is costly. In order to maintain the mortar weapons and archers in wars, a research was conducted to find the best number of mortar shells that will be fired until a preventive replacement for mortar weapons is implemented

    Estimation of Parameters in Groundwater Modeling by Particle Filter linked to the meshless local Petrov-Galerkin Numerical Method

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    The present study employs a mathematical method, i.e. Particle Filter (PF), to accurately estimate the parameters of three standard aquifers. The method is linked to a new developed numerical method, i.e. meshless local Petrov-Galerkin based on the moving kriging method (PF-MLPG-MK), to determine the aquifer parameters such as hydraulic conductivity coefficient, transmissivity coefficient, and storage coefficient or specific yield appropriately. For this purpose, a set of particles scattered in the state space. Each particle has two features: location and weight. Particles with greater weight values have the closer location to the estimation. Weight values which are assigned to each particle is computed based on the maximum likelihood function. This function is calculated in MLPG-MK simulation model. Overall, by linking particle filter model to the accurate simulation model, an efficient estimation method for aquifer parameters is obtained. This model applied to three standard aquifers. In the first standard aquifer, the estimated parameters of hydraulic conductivity and specific yield were 30.21 and 0.143, respectively. However, the exact values are 30 and 0.15. Also, in the second standard aquifer, the predicted transmissivity and storage coefficients were 99.7038 and 0.001057 whereas their true values are 100 and 0.001. In the third aquifer, the exact value of six parameters were achieved. The sensitivity analysis of the number of particles was carried out. Results revealed that with increasing the particles more accuracy will be achieved. 60, 80 and 100 particles were considered in the model. Results for 100 particles showed more accuracy

    Up-to-date Treatments of Primary Hyperhidrosis with Focus on Sympathectomy and Sympathicotomy; a Narrative Review

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    Background: Primary hyperhidrosis (PH) refers to excessive sweating, beyond normal physiological levels, in specific sites of the body for unknown reasons. It is usually bilateral and is most prominent in the palms, axillae, feet, and face. PH prevalence is estimated to be 0%-6.1% in different populations. It usually begins in childhood and is more frequent in women. In 57% of cases, there is a positive family history. It is an autosomal dominant disorder with variable penetration in chromosomes 5, 14, or both. Objective: The aim of this study was to illustrate current treatments of PH while focusing on surgical therapies through a narrative review. Methods: A complete search of online articles from 2007 to 2014 in PubMed, Scopus, and the Cochrane Library was performed. A free search and a search in the MeSH database for the study’s keywords were also done. More than 600 relevant articles were found, of which 51 were chosen for this study. This article is based on those articles. Results: Surgery is the best and more permanent therapy for PH. The most common consequences of surgery are compensatory sweating and gustatory sweating. There is controversy concerning whether lowering the level and limiting the number of ganglia on which surgery is performed reduces compensatory sweating. Conclusion: It seems that ramicotomy (selective division of the sympathetic postganglionic fibers) reduces compensatory sweating, but this theory should be confirmed with more studies

    A New Hybrid Method for Redundancy Allocation in Production Systems using Modified NSGA-II and MOPSO Algorithm

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    This paper presents a multi-objective mathematical model for redundancy allocation in production systems. In many of the production and assembly lines, process times, time between failures and repaired times are generally distributed. The proposed method of this paper is able to consider time dependent parameters as general distribution functions by using the hybrid approach of simulation and response surface methodology. The objectives of the mathematical model are maximizing production rate, minimizing total cost and maximizing quality. In order to solve the proposed mathematical model, non-dominated sorting genetic algorithm and multiple objective particle swarm optimization are used. Numerical results indicate the effectiveness of both algorithms for generating non-dominated solutions. Moreover, comparative results indicate the superiority of the Non-dominated sorting genetic algorithm

    Inverse modeling application for aquifer parameters estimation using a precise simulation–optimization model

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    Abstract In this research, a simulation–optimization (S/O) model is used in order to estimate aquifer parameters on two aquifers. In this model, meshless local Petrov–Galerkin (MLPG) is used for simulation purpose and modified teaching–learning-based optimization (MTLBO) algorithm is engaged as optimization model. Linking these two powerful models generates a S/O model named MLPG-MTLBO. The proposed model is applied on two aquifers: a standard and a real field aquifer. In standard aquifer, parameters are only transmissivity coefficients in x and y direction for three zones. The acquired results by MLPG-MTLBO are really close to true values. This fact presents the power of MLPG-MTLBO inverse model. Therefore, it is applied on field aquifer. Unconfined aquifer of Birjand recognized as real case study. Parameters which are needed to be estimated are specific yields and hydraulic conductivity coefficients. These parameters are computed by MLPG-MTLBO and entered to the groundwater flow model. The achieved groundwater table compared with observation data and RMSE is calculated. RMSE value is 0.356 m; however, this error criterion for MLPG and FDM is 0.757 m and 1.197 m, respectively. This means that estimation is precise and makes the RMSE to reduce from 0.757 to 0.356 m, and also, MLPG-MTLBO is an accurate model for this aim

    Scheduling trucks transportation in supply chain regarding cross docking using meta-heuristic algorithms

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    In today’s competitive world, the organizations decide to establish competitive benefits by making benefit from management sciences. One of the most important management sciences arisen lots of so useful matters is the supply chain. The supply chain management is the evolved result of warehousing management and is regarded as one of the infrastructure and important concepts for implementing the career so that in many of them it is essentially tried to shorten the time between the customer’s order and the real time of delivering the goods. Cross docking is one of the most important alternatives for lowering the time in supply chain. The central aim of this paper is to focus on optimizing the planning of the trucks input and output aiming to minimize total time of operation inside the supply chain in designed model. Timing the transportation in this paper makes the time between sources and destinations, time of unloading and transferring the products minimized. To find the optimum answers to the question, genetic algorithms and the particle swarm optimization have been used. Then, these algorithms have been compared with the standards such as the implementation time and quality of answers with each other and then better algorithms in each standard identified

    Proposing a Model for Calculating Amount of Incentive Payments to Employees Using Multiple Criteria Decision Making

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    Managers in organizations. In this paper an innovative model for calculating amount of incentive payments to employee has been proposed. Considering the multi criteria nature of assessing organization’s employees, this research propose a methodology to face this problem using multiple criteria decision making technique. To evaluating the effectiveness of this model, the suggested model has been implemented for an electromotor manufacturing company and the results has been mentioned in article. Considering the high ability of TOPSIS technique in solving the large scale (large number of alternatives and criteria), this technique will be used for computations. The suggested model has been used for five production departments (163 persons) in mentioned company and amount of incentive payment for each one of employees has been calculated

    Make or buy decision considering uncertainty based on fuzzy logic using simulation and multiple criteria decision making

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    Decision making on making/buying problem has always been a challenge to decision makers. In this paper a methodology has been proposed to resolve this challenge. This methodology is capable of evaluating making/buying decision making under uncertainty. For uncertainty, the fuzzy logic and simulation approaches have been used. The proposed methodology can be applied to parts with multi stage manufacturing processes and different suppliers. Therefore this methodology provides a scale for decision making from full outsourcing to full manufacturing and with selecting appropriate supplier

    Routing- Location for Hazardous Materials with Considering Risk Criterion in Hub Framework Network by Meta-heuristic Algorithms

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    Hazardous materials which are materials due to their chemical and physical properties impose significant risk to the safety of people and the environment. It's more complex routing transport of such material than normal materials. The Combination of the two subjects as the problem of locating and routing, it has created unified system to locating- routing problems. These problems determined optimal number and location of facilities at the same time and also set the optimal number of vehicles and their routes. The purpose of this study was design a network for the transportation of hazardous materials and includes supply levels, distribution (hub) and customers. Hence, it presented a mathematical model in order to minimizing costs and risk simultaneously. Hazardous materials sent from supplier to the hubs and deliveries to customers from there via routing by road transportation. It should be mentioned that in proposal model the hubs been locating In order to validate the model, prepared code GAMS In software and for the exact solution, sample problems with various dimensions were produced in the form of smart and random. For this purpose, was written an algorithm design in Matlab software. According to the problem was NP-Hard, presented a hybrid algorithm based on simulated annealing and genetic algorithms to solve large-scale. At the end of research the proposed algorithm were compared with the results of exact solution

    Modeling the problem of courses timetabling in a small educational institute

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    In this paper, we will consider the problem of courses timetabling in a small educational institute. We will present the mathematical model considering six hard constraints (compelling constraints) and five soft constraints (constraints that are lot compelling, but regarding them results increasing the utility of timetable). To formulating the model we will use a type of goal programming. In this paper we will try to define decision variables, hard constraints, soft constraints and objective function in a step by step direction. Afterward we will test the model on a mathematical example
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