Sharif Digital Repository

Planning orders and inventory is one of the most important issues in the planning of petrochemical production. Considering the customization of this industry, orders planning includes a large part of it. Also, in order to reduce the great cost of inventory storage, planning to reduce inventory must be considered. In this regard, we intend to present a model with simultaneous consideration of orders and inventory planning in this research, the ability to decide on acceptance of orders and determine the level of production of products in conditions of uncertainty of demand with random trapezoidal demand in each period can be assumed. This model will practically play a key role in improving... 

In real production systems, the process is always bound with the production of faulty items which different approaches may be taken toward handling these low quality items according to the nature of the industry and product. Repairing, discarding or selling items in a secondary market are some of the possible actions. We investigated the essentiality of coordinated decision making between a supplier and a buyer in this environment hence developing a model to minimize total costs of two parties with an attitude towards improving quality of production system. In common two layered supply chains, the buyer defines the economic order quantity (EOQ) according to its own decision criteria. These... 

This research deals with the problem of dynamic pricing of perishable assets. In this problem there are two sources of randomness: the arrival rate of customers and their reservation prices. In most studies considering this problem, it’s assumed that process of arrivals of customers follows a Poisson process with a given intensity. Thus this process is assumed to have independent increments and the information regarding the arrival times of previous customers doesn’t have any influence on the distribution of arrival times of future customers. In some recent studies it’s assumed that customers’ arrivals follow a conditional Poisson process with an unknown intensity. The distribution of this... 

Power distribution network planning and related optimization is an interesting research subject and many papers have been published on this topic. Distribution network planning started in developed countries. Therefore network models are based on reliable network data, educated crew and low interest rate. Nowadays, Iranian engineers and researches try to use their research result for solving network optimization problems but sometimes the result of optimization is not achievable in reality. In current thesis, modeling approaches developed by previous researchers were compared and the effect of model simplification was evaluated. This evaluation was based on data gathered from local power... 

Facility layout problem (FLP) is one of classical optimization problem in engineering science. The theoretical attractiveness and practical applications of the problem have created a rich literature in the FLP. There are varieties of measure of effectiveness’s for the FLPs, such as minimizing the space cost; minimizing the handing cost; maximizing the adjacencies; maximizing the safety and etc. Maximization of the adjacencies is a common measure of effectiveness, which is addressed in many related literatures especially, in continuous process facility layout. Using of the classical definition of the adjacency usually impose some restrictions on the layout designs. Due to these restrictions... 

Multi core processors are becoming mainstream in the computation area, wide application of multi core processors in Engineering, Industrial purposes and scientific applications made them popular among users and Manufacturers, cloud computing is a very well known Concept which technically is a Multicore processing environment, most of Businesses, enterprises and engineering works nowadays are getting done by the help of cloud services, hence, to get the best of these multi core cloud computing systems, scheduling of the tasks on the cores and virtual machines(VMs) is necessary, which is the answer to two questions: each task must be assigned to which core(VM)? And What is the order of... 

Population and urbanization increase, intra-city travel and the use of private cars have created problems such as traffic, higher fuel consumption and air pollution. One of the approaches to deal with this phenomenon, which has been in center of attention in recent years due to the growth of technology and development of ride-hailing platforms on mobile phones, is using shared vehicles and travel sharing.The assignment problem in ride-sharing is a group of VRP problems and is classified as an NP-hard problem. Due to the high volume of demand from passengers and supply from drivers, as well as the need for fast response to reduce waiting time for passengers and drivers, there is a need to... 

The quality is the last word of customer satisfaction concept. The structure and the main goal of many of large and small companies have been formed with systems aggregate related to process and product quality. Whereas quality is not achieved only under the protection of inspecting and controlling, then the quality management standards have been designed and produced to control all the activities and organization effective processes. Quality management standards in auto industries have been developed with increasing of customer desire and their severity simultaneously. Which the set of some standards such as ISO 9000, QS 9000, VDA, … and the most ISO TS 16949 requirements have been used.... 

In this thesis, we study a queuing system with one server in which customers differ in both sensitivity to delay and willingness to pay. In this system, the server’s goal is to design a mechanism in order to maximize her revenue. It is worth to mention that nonlinear delay cost is implemented.Making use of the achievable region approach, we show that a well-designed menu of probabilistic admission control along with priority pricing contracts, may force customers to reveal their true valuations and at the same time induce customers that are more sensitive to delay to opt for higher priorities. Thus, the probabilistic admission control allows the server to identify the customers that are... 

This thesis is related to applying survey of scientific inventory control methods in Khoramshahr Oil Extraction Company (KHOEC). KHOEC is the producer of edible oils in I.R of Iran and is a subset of E.T.K.A holding organization. The inventory costs of high consuming items are studied and optimized based on the optimal ordering policy (r, Q). First, the company raw materials are identified and classified based on ABC analysis method. For developing the new method of inventory control, the demand for each item is predicted, and the probability distribution of demand during the lead time is determined. Then according to this information and the desired service level of management, order point... 

This thesis presents a location- inventory model for dual-channel supply chains .Dual-channel supply chains have two channels for sale the traditional in-store (retail) channel and the online (retail) channel.The model assigns online demands to the capacitated stores currently serving in-store demands. Keeping the delivery network of the in-store demands unchanged, the model aims at minimizing the summation of transportation cost, inventory cost, and fixed handling cost in the system while assigning the online demands. We assume that at the beginning of each period a distribution center which just distributes products to the stores, follows an order-up-to policy which increases the total... 

In this paper, we consider a three-echelon supply chain consisting of a producer, a distributor and a retailer. Generally each echelon tends to minimize his own inventory costs. On the other hand, competitive environment of business market, force companies to develop strategic alliances. In order to boost their partnership, separated echelons must integrate their policies, so that the total cost of the system be minimized. The model, extends the research of Wang et al.(2011) by changing the No shortage assumption into backlog shortage model.
This study assumes different deterioration rates among different echelons, and deterioration rates are time-sensitive, which is very helpful in... 

Inventory control has been always considered important due to its prominent role in managing and better application of resources in the field of operational systems. Ordering system or review stock policy in supply chain management can be mentioned as one of the inventory control study fields of management. A lot of researches have been done in investigating ordering system in supply chain under certainty conditions; however, since the real world is full of uncertainties, parameters such as demand cannot be predicted exactly and we encounter with ambiguity. In this case, using crisp (exact) values can cause to decide wrongly (a wrong decision). On the other hand, due to absence of sufficient... 

In the present research a two stage supply chain is considered. In its first echelon, there is a producer that produces both perfect and defective items. Defective items are reworked by producer and no defective item is produced during the reworking process. There is a buyer in second echelon of the supply chain that faces constant demand and orders fixed batches in fixed periods to the producer. So in each complete cycle of production, multiple orders are received from buyer. Two different policies for reworking are investigated in this research. In the first policy, reworking is done in the same cycle that producing is conducted but in the second one all defective items that are produced... 

In recent years, numerous companies in various industries apply supply-chain management to improve their market competitiveness. Advances in information technology bring new approaches for managing supply chain activities. Consequently, emphasis on supply-chain coordination has increased in recent years. Vendor managed inventory (VMI) is an important coordination initiative. In VMI, the vendor assumes responsibility for managing inventories at retailers using advanced online messaging and data-retrieval systems. In this dissertation we investigate the effect of VMI on supply chain performance under make-to-order and make-to-stock environment. By using renewal reward theorem, we derive the... 

One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s... 

Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and... 

Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework... 

The new lateral load resisting system introduced in this dissertation is a kind of squat composite shear wall consisting of a concrete core as filler and two steel corrugated sheets as cover. Reinforced bars are not used in this kind of construction. Load resisting process of the walls is provided by 3 factors: concrete core, steel corrugated covers on both sides of the central core and shear-friction interaction between the core and covers. There is not any specific formula for their design because of their novelty and few researches on this kind of walls and absence of code provisions. In this project, squat composite walls were constructed with dimensions of 106.8×90 (cm2) from corrugated...