Sharif Digital Repository

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 this thesis we investigated a two level seller-buyer supply chain by game theoretical approach. We formulated interaction between seller and buyer as stackelberg game. In seller-stackelberg game , seller role as leader and buyer as follower. likewise in buyer-stackelberg buyer is leader and seller is follower. In our model the demand is an equation in which the dependent variable is a linear function of three independent variables and a disturbance term. The three independent value in demand function are marketing cost , wholesale price , retailing price. The disturbance term in demand function has normal distribution by constant variance and zero expected value. Sale amount considered as... 

Increases in food prices after the energy prices reform in Iran 2010, have raised concerns about reductions in households’ wellbeing and food security. Particularly for the families in the lower income quintiles who spend large fraction of their earnings on food and sheltering. This research intends to evaluate the welfare consequences of the increases in commodity prices on Iranian urban households by making use of a two-stage Quadratic Almost Ideal Demand System (QUAIDS), censored data and Compensation criterion. The demand system is estimated based on cross-section data which are taken from households’ expenditures and income surveys for years 2010 and 2011. Our results show that the own... 

In recent years, magnesium and its alloys have been considered as biodegradable implants, but they corrode in the body before natural process of damaged organs recovery is completed. In this investigation PEO operation was used for corrosion control and effect of different parameter such as number of operation steps, electrolyte type, time and operation voltage on coating properties was studied. Scanning electron microscopy was used for investigating of morphology of coats and to determine chemical composition and phase of coats EDS analysis and X-ray diffraction were used. The corrosion resistance of samples were evaluated by potentiodynamic polarization and electrochemical impedance (EIS)... 

Power distribution systems have been traditionally operated as passive networks which consume electric power supplied by the transmission grid. Increasing utilization of wind energy in distribution systems, notably wind energy, is changing the way distribution sys-tems are operated. The distribution system operators (DSO) would operate the available wind power for reducing the power purchased from the wholesale market. However, high penetration of wind energy in distribution systems would require advanced operation mod-els and additional flexibility in system to offset the variability and uncertainty associated with wind energy. In addition, wind availability often does not positively... 

Powder metallurgy is one of the most important and most usable methods in industries. Nowadays, many of the specimens are made this way. In this method, after powder compaction stage, because of sintering in high temperature, crystallographical structure of the material changes. This change results in poorer strength than initial powde. In order to avoid change and decrease in powder strength, shock consolidation is used. In this research, because of complication of this phenomenon and final quality of the specimen, shock consolidation of metal powders is investigated and analysed. This phenomenon is modeled, simulated, analysed and optimized mathematically.Various methods are used to create... 

Improvement of biological properties by modifying the composition and morphology of the surface layer is one of the main goals of using plasma electrolytic oxidation (PEO) for coating titanium implants. The purpose of this research is formation of biocompatible coating containing calcium, phosphorus and silicon on titanium by two-step PEO method in DC, constant voltage mode. In addition to good corrosion properties of the resultant coatings in simulated body environment (SBF), Having good adhesion due to the use of electrolytes with useful elements for biological function in both step of coating process rather than acidic electrolytes which are incompatible with the body environment, this... 

The present study proposes a pricing model for manufacturing and customer support companies which is carried out in the form of multi-level programming. In this model, the manufacturer is considered as the leader and supporting companies as followers. In fact, manufacturer sets up the price level for its customer support first and then according to this price level, customer support companies choose their products and specify the level of after-sales services and the prices. The purpose of this study is to provide insight into the analysis of the after-sales services in a supply chain. The results can be notable for managers in order to demonstrate the impact of different strategies of... 

This Thesis presents a robust network design model for supplying blood during and after an earthquake disaster. A two stage optimization model based on several real-world scenarios is developed. The purpose of this research is to locate and allocate fixed and mobile facilities in probabilistic situation, in which Tehran city with 22 districts is considered as a case study. This model can be categorized as a probabilistic model which demand and supply rate for blood and its derivatives is uncertain. Furthermore the blood transition between different blood types and conversion to its derivatives such as Platelet and plasma are involved in the proposed model. The supply chain for blood consists...