Sharif Digital Repository

The integrative supply chain management is one of the main business processes between final consumer and supplier and it is formed by responsibilities such as production, services and information those have added value for customers and beneficiaries. Therefore and as the goal of a chain is maximization of gained value for the factors involved in chain, so, this goal can be more accessible by decreasing transportation (transportation method, tracking, …) and stock costs (conservation, ordering, …). As its purpose, this thesis intends to introduce and increase the options of goods transportation possibilities between retailers’ warehouses and evaluation of its effect on transportation and... 

Emerging non-volatile memory technologies such as Spin- Transfer Torque RAM (STT-RAM) or Resistive RAM (ReRAM) can increase the capacity of the last-level cache (LLC) in a latency and power-efficient manner. These technologies endure between 109 to 1012 writes per cell, making a non-volatile cache (NV-cache) with a lifetime of dozens of years under ideal conditions. However, non-uniformity in writes to different cache lines can considerably reduce the NV-cache lifetime to few months. Writes to cache lines can be made uniformly with wear-leveling. A suitable wear-leveling for NV-cache should not incur high storage and performance overheads. We propose a novel, simple, and effective... 

Selective laser sintering is a technique which uses a laser as the power source to sintering some selected points at a bed of powder in order to create a solid structure. In this research the SLS mechanisms of powder deposition is simulated and surface smoothness and layer density created by each mechanism is computed. For this purpose roller, blade and hopper mechanisms are simulated. For this simulation, polyamide 12 (PA2200) which is a common material is used. In this simulation at first powder specifications are extracted according to the references and for particle shape instead of using the spherical particle shape we use a certain shape that is more close to reality which created by... 

Global energy consumption is on a trajectory to surge by 50% by 2050, primarily driven by prevailing energy consumption patterns. Consequently, the imperative to innovate and develop novel energy sources, such as the utilization of recycled waste heat, has become paramount for the foreseeable future. In light of this, this paper delves into the transformative potential of employing Phase Change Materials (PCMs) for cooling Thermoelectric Generators (TEGs) and harnessing waste heat for productive purposes. The research investigates three distinct configurations to evaluate the efficacy of PCMs in enhancing thermal management. Configuration 1 exclusively relies on an active cooling fan, while... 

This study was conducted to investigate a theoretical and experimental two-dimensional model of a floating fish cage in regular waves and uniform current. Due to the inefficiency of computational fluid dynamics (CFD) in solving such problems, developing a simple model to predict the results is highly advantageous. In this study, a simple mass-spring model was developed to simulate the problem. After validating the results of this simple model through a series of model tests in a wave tank, it was further utilized to extract additional results. Experiments were conducted at six different wave heights and four current velocities. In all experiments, wave steepness was maintained at a ratio of... 

In this research, we propose a formulated approach to locate and allocate two level of a three-level closed-loop supply chain consist of a number of capable points production facilities, redistribution centers and customer clusters for multiple products in multiple time periods. Also, we consider environmental aspects in this supply chain network by taking into account an objective function, aside from cost objective function, in the template of emitted carbon dioxide. In this research for the first time we consider vehicles’ emitted CO2 different in each period which is a result of gradual depreciation of vehicles. In the end for the sake of validating model’s performance we developed few... 

Environmental problems and the consequent governmental regulations, has led supply chains into reverse and closed-loop supply chains. Application of problems such as "Vehicle Routing Problem” has diminished in the closed-loop supply chain, and instead of them, the problem of "Vehicle Routing Problem with Deliveries and Pickups" has become more important. On the other hand, tendency of supply chains to running information in the chain in a desired way, has led to grow the attention to establishing policies of “Vendor Managed Inventory". It seems that by tending the supply chains to closed-loop supply chains which are utilizing the policy of "Vendor Managed Inventory", application of problems... 

Mechanical behavior of tissue engineering scaffolds plays a key role in their biological performance; however the effect of microstructural features on mechanical behavior of such scaffolds is still under investigation. The objective of this study was to investigate the influence of pore architecture and relative density on mechanical behavior of rapid prototyped scaffolds. In this regard, scaffolds with different cubic, hexagonal and trigonal unit cells were designed. These unit cells were repeated in different arrangements in 3D space to produce different nodal connectivities. The internal dimension of pores varied from 500 to 600 μm. Plastic models of scaffolds then fabricated by 3D... 

Pooling Lead-time risk by splitting replenishment orders simultaneously among multiple suppliers is a sourcing policy that has attracted the attention of academic researchers for some years. While they consider many different assumptions in their models, they don’t pay attention to deterioration items in order splitting models. In this thesis, we have considered order splitting policy about products with constant deteriorating rate and developed two inventory models. In the first model, it is assumed that the whole requirement supply from only one source, whereas in the second two suppliers are accessible. Then after determining the optimal policy, by numerical search and use of MAPLE... 

In recent years, Supply Chain Management has become one of the most desired concepts for Industrial engineers. In this thesis, specifically, one of the SCM’s aspects, Joint Economic Lot Sizing1, which in literature have been studied by various people with different viewpoints, is considered and a two-stage supply chain facing certain demands is studied. These demands are changing as a function of selling price determined by a supply chain and the goal is to increase the chain’s total profit in comparison of individual policies in which members decide about their profits separately. The optimal amount of selling price varies end-customer demands exponentially and leads to changes in economic... 

Locating wireless transmitters is one of the most important issues. That’s why many researchers have worked in this subject recently. Communication Engineers always want to optimize the productivity of wireless transmitters. They prefer to cover a region completely by minimum cost, so they use analytical tools for solving this kind of problems. This type of optimization is very useful for cellular Networks. There is a different kind of wireless services such as high-speed Internet services; their goal is maximizing the covered demand points by minimum cost not covering all of them. Experts use maximal covering location problem for modeling this kind of problems. At first, an extension of one... 

Inventory problems are studied for a long time and many authors have investigated models with shortage phenomenon. To reduce inventory holding cost or decaying items we can have a shortage period in witch a part of demand is backordered; Although we pay fines to pending costumers, as shortage period is extended a larger portion of them will refuse to wait until replenishment. So, calculating an optimal duration for on hand inventory and shortage period with respect to inventory costs has became an interesting research field. However, related studies are rarely appeared in supply chain researches, where an integrated inventory model for a supplier and a retailer is proposed; especially when a... 

Success in a business will be met by the different factors, of which one of the most important is design and execution of a good business model upon the inauguration of each company. Indicating the commercialization of innovations and innovative commercial ideas, it shows the productivity of innovation. Outsourcing the Training management in organizations is an issue the world pioneer organizations feel its necessity. Training systems in organizations have limited resources, don't have the required knowledge and financial sufficiency for effective execution of all Training processes. Therefore, Training management outsourcing may be a good alternative for meeting perspective and facilitating... 

This thesis studies a multi-product location-routing-inventory problem in which location-allocation, inventory and routing decisions are to be taken in a three-level supply chain including suppliers, depots and customers. Each product for each depot could be supplied by more than one supplier and each supplier has a limited supplying capacity per period. Products are distributed from depots to customers by a homogeneous fleet of vehicles. Backlogging is allowable for each customer on the condition of not exceeding a fraction of customer’s demand. A mixed-integer programming formulation is presented to describe the problem then a new hybrid heuristic algorithm based on the simulated annealing... 

In this thesis, two Inventory-Routing Problem models, under vendor managed inventory policy are presented. In the first proposed model, despite the previous researches, transshipments between retailers are permitted and the problem is modeled by the assumption of reverse flow in the distribution network. Based on the first model, we also formulate a new model for the Pallet managing problem. Since the inventory routing problem is known as NP-Hard, genetic and variable neighborhood search algorithm has been applied to determine an acceptable upper bound for the first model in different instances. In the next step a Lagrangian relaxation method is developed for finding a near optimal solution... 

Optimizing multi-period modern distribution system is a challenging task due to high costs of constructions in urban areas and importance of fast and cheap goods delivery to customers. Various logistic techniques have been proposed to solve this issue. In this study, a new method is suggested to convert the strategic problem of finding depot location into a tactical problem. In addition, a vehicle routing method for multi-period distribution systems in high demand periods have been developed. For modeling this location-routing problem two objective functions have been considered as fallows minimizing the total time in the system to satisfy customer demand and operating costs. To solve this... 

The results also have shown that holding costs and inventory play key roles because of business various conditions and external risk encountering. As a result, supply chain systems have to decrease their inventory amount.In this study, a location-routing-inventory model hypothesizes using risk pooling in distribution center warehouses and their combination in order to decrease the inventory costs such as inventory holding and safety stock costs.(it is because of costumer uncertain demand and lead time from supplier to distribution center and from distribution center to costumers) In this model, in addition to decrease the inventory costs, DC establishment costs and transportation costs that... 

In this thesis, a new hub-and-spoke location problem is investigated in which, the location of spoke nodes should be decided upon, in addition to the location of hub nodes. Three research problems are investigated: In the first problem, the goal is to determine both hub and spoke node locations. In this problem, the objective function considers the following costs, to be minimized: flow transportation costs, lost demand costs, in addition to the hub and spoke location costs. The demand distribution among different nodes follow the gravity rule, and the hub network is considered to be fully connected. Following the gravity rule, the demand among different node is not set a priory and depends... 

This research solves a Location-Routing model based on the data of Tejarat bank branches in Tehran. The goal of the model is to minimize the cost of building & operating bank treasuries, optimize the cost of money transferring to branches of the bank & reduce the stealing risk. Because of the wide range of definitions for risk, time parameter is used as risk factor for its importance in bank money car stealing. Non-dominated Sorting Genetic Algorithm which is a common algorithm in multi-objective optimization literature with big data, is used to solve the proposed model  

Logistics activities and matters related to supply chain management play an important role in the success of supply chain in today’s competitive business environment. The success of an organization depends on the proper functioning of the whole supply chain organization. SCOR model as a reference model for supply chain management is a suitable framework to manage all aspects of the supply chain and enables the creation of an appropriate and efficient structure in supply chains. In this thesis the Procurement department of a petrochemical company is examined and the current state of the supply chain is explained and then based on the SCOR model, in 4 areas: Performance (indices), Processes,...