Current Issue : January - March Volume : 2014 Issue Number : 1 Articles : 6 Articles
Production planning and control (PPC) systems have to deal with rising complexity and dynamics. The complexity\r\nof planning tasks is due to some existing multiple variables and dynamic factors derived from uncertainties\r\nsurrounding the PPC. Although literatures on exact scheduling algorithms, simulation approaches, and heuristic\r\nmethods are extensive in production planning, they seem to be inefficient because of daily fluctuations in real\r\nfactories. Decision support systems can provide productive tools for production planners to offer a feasible and\r\nprompt decision in effective and robust production planning. In this paper, we propose a robust decision support\r\ntool for detailed production planning based on statistical multivariate method including principal component\r\nanalysis and logistic regression. The proposed approach has been used in a real case in Iranian automotive industry.\r\nIn the presence of existing multisource uncertainties, the results of applying the proposed method in the selected\r\ncase show that the accuracy of daily production planning increases in comparison with the existing method....
In this paper, we apply continuous review (S-1, S) policy for inventory control in a three-echelon supply chain (SC)\r\nincluding r identical retailers, a central warehouse with limited storage space, and two independent manufacturing\r\nplants which offer two kinds of product to the customer. The warehouse of the model follows (M/M/1) queue\r\nmodel where customer demands follow a Poisson probability distribution function, and customer serving time is\r\nexponential random variable. To evaluate the effect of considering bi-product developed model, solution of the\r\ndeveloped model is compared with that of the two (M/M/1) queue models which are separately developed for\r\neach product. Moreover, and in order to cope with the computational complexity of the developed model, a\r\nparticle swarm optimization algorithm is adopted. Through the conducted numerical experiments, it is shown that\r\ntotal profit of the SC is significantly enhanced using the developed model....
Practical implementation of a STEP-based architecture to provide a fully integrated and interoperable platformof data exchange has\r\nalways been an intriguing issue. A variety of CAD/CAM environments are struggling to embed and support STEP standard and its\r\nprotocols in order to seamlessly operate within global data exchange. However, apparent paucity of efficient and reliable structure\r\nfor data communication, manipulation, and restoration has remarkably hindered the desired progress. In this paper, taking these\r\nshortcomings into account, a practical architecture is introduced and STEP-based agents are implemented and installed on the\r\nplatform.Moreover, feature recognition, interaction, and machining precedence as crucial issues of CAD/CAM research have been\r\nconsidered in developing the interoperable platform. Seamless integration and interaction of CAD/CAM modules are provided in\r\nthe proposed system. The prototype is finally verified and discussed through a case study....
We present a new analytical expression for the moment generating function (MGF) of the end-to-end signal-to-noise ratio of\r\ndual-hop decode-and-forward (DF) relaying systems with relay selection when operating over Nakagami-?? fading channels. The\r\nderived MGF expression, which is valid for arbitrary values of the fading parameters of both hops, is subsequently utilized to\r\nevaluate the average symbol error probability (ASEP) of ??-ary phase shift keying modulation for the considered DF relaying\r\nscheme under various asymmetric fading conditions. It is shown that the MGF-based ASEP performance evaluation results are\r\nin excellent agreement with equivalent ones obtained by means of computer simulations, thus validating the correctness of the\r\npresented MGF expression....
A quick and simple approach for reactorââ?¬â?emergency relief system designââ?¬â?for runaway chemical reactions is presented. A\r\ncookbook for system sizing with all main characteristic dimensions and parameters is shown on one realistic example fromprocess\r\nindustry. System design was done based on existing theories, standards, and correlations obtained from the literature, which were\r\nimplemented for presented case. A simple and effective method for emergency relief system is shown, which may serve as an\r\nexample for similar systems design. Obtained results may contribute to better understanding of blow down system frequently\r\nused in industrial plants, for increasing safety, decreasing explosion damage, and alleviating the ecological problems together with\r\nenvironmental pollution in case of industrial accidents....
This work presents a novel fabrication approach of multiwalled carbon nanotubes (MWNTs) reinforced copper (Cu) matrix\r\nnanocomposites. A combination of nanoscale dispersion of functionalized MWNTs in low viscose media of dissolved paraffin wax\r\nunder sonication treatment followed by metal injection molding (MIM) technique was adopted. MWNTs contents were varied\r\nfrom 0 to 10 vol.%. Information about the degree of purification and functionalization processes, evidences on the existence of the\r\nfunctional groups, effect of sonication time on the treated MWNTs, and microstructural analysis of the fabricated Cu/MWNTs\r\nnanocomposites were determined using TEM, EDX, FESEM, and Raman spectroscopy analysis. The results showed that the\r\nimpurities of the pristine MWNTs such as Fe, Ni catalyst, and the amorphous carbon have been significantly removed after\r\npurification process. Meanwhile, FESEM and TEM observations showed high stability of MWNTs at elevated temperatures and\r\nuniform dispersion of MWNTs in Cu matrix at different volume fractions and sintering temperatures (950, 1000 & 1050�°C). The\r\nexperimentally measured thermal conductivities of Cu/MWNTs nanocomposites showed remarkable increase (11.25% higher than\r\nsintered pure Cu) with addition of 1 vol.% MWNTs, and slight decrease below the value of sintered Cu at 5 and 10 vol.% MWNTs....
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