Sharif Digital Repository

This thesis covers the problem of a 2-echolen inventory system including a producer and retailer. Producer makes each part and stores it in its own warehouse which is capable of holding as many as S parts. Time that takes for the producer to produce each part is described by an exponential distribution with a fixed rate. Retailer which has its own warehouse with capacity R sees customers arriving with a Poisson distribution. If either of retailer or producer is out of inventory, system does not accept new customers and it is a lost sale, otherwise the customer is served. Whenever retailer runs out of stock, it places an order of size R. producer then looks at its own inventory, if possible a... 

Due production and use of large amount of chemical and emissions of pollutants in air, detection and control of these compounds are necessary. One of the common methods to detect these pollutants in the ambient is using metal oxide semiconductor sensors. However, these types of sensors suffer from low selectivity toward a certain compound in the mixture of different gas components. In this study, the object was to investigate the effect of different amount of CNTs on performance of tin oxide to improve their selectivity for detection of 50 ppm of hydrogen sulfide at low temperature. To perform the study, nanoparticles of pure tin oxide and SnO2 base hybrids containing 0.25wt%, 0.5wt%, 2.5wt%...