Sharif Digital Repository

The economic production quantity (EPQ) is one of the most commonly used models for production planning and inventory control problems. In this paper, a multi-product single- machine EPQ inventory model with imperfect production is extended under production capacity. In this system, produced items do not have perfect quality; they either are reworked or are scrapped. Moreover, the limited warehouse space for each item and the limited total available capital lead to constraints for storage and budget, respectively. Besides, the setup cost/time for each product depends on the quantity produced. The objective function of the developed EPQ inventory model is shown to be a convex non-linear... 

To stay competitive in the new dynamic market having large fluctuations in product demand, manufacturing companies must use systems that not only produce their goods with high productivity but also allow for rapid response to market changes. Reconfigurable manufacturing system (RMS) is a new paradigm that enables manufacturing systems to respond quickly and cost effectively to market demand. In other words, RMS is a system designed from the outset, for rapid changes in both hardware and software components, in order to quickly adjust its production capacity to fluctuations in market demand and adapt its functionality to new products. The effectiveness of an RMS depends on implementing its... 

In this study, mathematical modeling of fixed-bed plasma reactor operated under isothermal condition was investigated. In this process, methane and acetylene were the inputted feed and ethane, ethylene, propylene, propane, i-butane, and n-butane were the output products. The amount of methane conversion obtained was 12.7% for the former feed, however, if pure methane was inputted this conversion rose to 13.8%. Furthermore, the plasma process enhanced the conversion as well as the selectivity toward the desired product and yield. In the present study, when methane and acetylene were fed at a molar ratio of CH4/C2H2 = 10 to the reactor, the selectivity of C2, C3, and C4 hydrocarbons was... 

Firms performance in their new product development (NPD) is believed to be positively related with involving suppliers in the process of new product development, and also with the organisations capacity and capability to absorb external and internal knowledge, namely absorptive capacity (AC). Addressing a gap in the literature, this study adopts the definition and structure for AC suggested by Tu et al. (2006) to examine relationships between ACs sub-dimensions with NPD performance, and also their moderating effects on the relationship between supplier involvement and new product development performance, on both financial and nonfinancial aspects. Data from a survey of 161 manufacturing... 

Today's manufacturing enterprises struggle to adopt cost-effective manufacturing systems. Overview of the recent manufacturing enterprises shows that successful global manufacturing enterprises have distributed their manufacturing capabilities over the globe. The successes of global manufacturing enterprises depend upon the entire worldwide integration of their product development processes and manufacturing operations that are distributed over the globe. Distributed manufacturing agents' collaboration and manufacturing data integrity play a major role in global manufacturing enterprises' success. There are number of works, conducted to enable the distributed manufacturing agents to... 

The nature of molecular transmitter imposes some limitations on the molecule production process and its storage. As the molecules act the role of the information carriers, the limitations affect the transmission process and the system performance considerably. In this paper, we focus on the transmitter's limitations, in particular, the limited molecule production rate and the finite storage capacity. We consider a time-slotted communication where the transmitter opens its outlets and releases the stored molecules for a specific time duration to send bit '1' and remains silent to send bit '0'. By changing the Release Duration (RD), we propose an adaptive RD modulation. The objective is to... 

Carbon accounting is necessary for designing effective climate change mitigation policies. A proper and fair accounting method should motivate both the producers toward cleaner production methods and the consumers toward reducing the embodied emissions of their consumption. This research work proposes a new approach to map the production chain of carbon emissions in which every subsystem is responsible for the level and efficiency of its production activities and embodied emissions for providing its economic activities or final demands. The exergy cost formation concept is used to track the emissions in the production chain. The results of this accounting present the total carbon loads on... 

A classical question of Yoneda asks when the tensor product of two injective modules is injective. A complete answer to this question was given by Enochs and Jenda in 1991. In this paper the analogue question for pure-injective modules is studied  

This note provides some extensions on optimal policies on price, warranty length and production rate proposed by Wu et al. (2009) . [1] (Wu, C.C.; Chou, C.Y.; Huang C. Optimal price, warranty length and production rate for free replacement policy in the static demand market. Omega 2009; 37: 29-39.) More specifically, the assumptions of the original paper is extended in this note from the production rate being positive and the second derivative of the demand function with respect to price and warranty-length being negative to no restrictions on both  

The modified eccentricity connectivity polynomial of a connected graph G is defined as Ξ(G; x)=Σ u∈V(G)d G(u)x ε′G (u), where ε′ G(u)=Σ v∈NG(u)εG(u)and d G(u) is the degree of u in G. In this paper modified eccentric connectivity polynomial is computed for several classes of composite graphs  

Some new relations have been established between Wiener indices, stability numbers and clique numbers for several classes of composite graphs that arise via graph products. For three of considered operations we show that they make a multiplicative pair with the clique number  

The aim of this article is presenting a new constrained multi-product pricing and inventory model in which perishable products are put into three categories: substitute, complementary and independent. The general demand is found by considering the relations of different products and the impact of their prices. The goal of the model is deciding on the prices as well as the inventory and production decisions in order to maximize the total profit. The derived model is a non-linear programming model and a genetic algorithm is developed for its solution. To enhance the performance of our genetic algorithm, we apply the Taguchi experimental design method to tune the parameters of the algorithm.... 

This article presents a new model for pricing a new product considering skimming pricing strategy in the presence of the competition. We consider two periods for price setting including skimming and economy period. The problem is deciding on a skimming price as well as an economy price in order to maximize the total profit. The derived model is a non-linear programming model and we analyzed the structure and properties of optimal solution to develop a solution method. Analytical results as well as managerial insights are presented by mathematical analysis and numerical analysis  

We consider the game of cops and robber played on the Cartesian product of two trees. Assuming the players play perfectly, it is shown that if there are two cops in the game, then the length of the game (known as the 2-capture time of the graph) is equal to half the diameter of the graph. In particular, the 2-capture time of the m×n grid is proved to be ⌊m+n2⌋-1  

A new counting polynomial, called Omega, was recently proposed by Diudea. It is defined on the ground of opposite edge strips "ops". The Sadhana polynomial has been defined to evaluate the Sadhana index of a molecular graph. A third one, called Theta polynomial is also derived from ops. In this paper we compute Omega, Sadhana and Theta polynomials of the Cartesian product graphs  

Integrated product development is comprised of CAD, process planning and CNC code generation based on an integrated data structure. To make various CAD/CAM software solutions with different internal product data structures interoperable, it is necessary to realise reliable and robust information exchange capability in a manufacturing environment. To enable interoperability amongst integrated product development processes, management of collaboration of diverse CAD/CAM software packages is of outmost importance. In this article, the fundamental requirements for achieving interoperability and collaboration management in an integrated, enterprise-wide, product development process environment...