Sharif Digital Repository

In this research, the synthesis of the electrospum nano fiber doped zinc oxide and its photocatalyst usage was investigated. The band gap of the zinc oxide in the area of UV leads to deactivation of this material at the visible light. With due the attention to sunny weather in Iran and the fact that about 50 percentage of sunlight is visible light, producing and usage of catalyst materials actived at visible light is economical. Doping is one of the ways of activating ZnO at visible light, so in this research thiourea is used as the source of ZnO doping. The results of the expriments done at visible light and also spectrums of DRS, XPS and XRD prove that the doping is happened. Also, in this... 

In today’s competitive world, using an efficient forecast method is necessity for companies. To now, many forecast methods have been developed, but many of them have not an expected efficiency. In this research, we develop a new hybrid forecast method with application of forecasting retails demand. The hybrid method is the combination of ARIMA method and neural networks. To test the efficiency of the method we use the 96 weeks data of plastic containers demand. We also comprise the hybrid method with other forecast methods including naïve method, ARIMA method and neural network method by applying root mean square error and mean absolute percentage error indexes. In the case of plastic... 

Developing to the sub-micron dimentions reduces the size of integrated circuits, so interconnects and a variations in their characteristics has more effects on circuit performance. Worst case study is the most common method in these systems, but in many cases interconnect lines are independent from eachother. Analysis state that worst case is out of the distribution in many cases (with zero possibility) and result in a pessimistic design. Statistical analysis should replace worst case analysis in multi varient systems. In this titile, statistical analysis will be used to investigate performance of interconnects in new technology. Maximum variation in interconnect parameters are considered... 

This research deals with a realistic cyclic three-stage supply chin consisting of one supplier, one manufacturer and one or more retailers, in FMCG environment. Orders from retailers are supposed to iterate over cycles and parallel machines are available to process perishable jobs with given release dates, due dates and deadlines. To start process of he jobs, perishable raw material, supplied by an external supplier, is required. Jobs are subject to post-production shelf life limitation and must be delivered to retailers during the corresponding time window bounded by due dates and deadlines. Both early and tardy jobs are penalized by partial weighted earliness/tardiness functions and the... 

Fountain codes enable wireless networks to adapt their transmission rates to the state of the channels, without the need for channel state information (CSI) at the transmitters. According to the following properties of rateless codes, ever increasing parity generation, mutual information receiver, single bit feedback, and information combining receiver, they are good choice for relay networks. In this research, the design of rateless codes for wireless relay networks has been studied. Cross layer issues should be seriously considered when using rateless codes in the packet level. One cross-layer scheme has been developed in this thesis and analysis show that the performance of the proposed... 

For application such as electrical contacts and spot welding electrodes, both high electrical conductivity and wear resistance are required. Additionally, such parts should have structural stability at evaluated temperature. Copper based composites containing carbides or oxides reinforcement can be the good choice for production of such parts. In present work, in-situ Cu/NbC composite via mechanical alloying with homogenous distribution of nano reinforcement particle has been produced. For this purpose, in first stage, copper powder was milled with 5, 8, 10 and 12 wt. % of niobium powder in two types of mills, i. e. vibratory dicky mill and planetary ball mill for 5 and 32 h respectively. At... 

One of the most important reasons of death in today’s world is the diseases related to cardiovascular system. Hypercholesterolemia is one of the most common forms of these diseases. There are a lot of experiments for diagnosing this disease, which are classified into two groups: invasive and noninvasive experiments. One of the well-known noninvasive experiments in this area is the photoplethysmography in which the changes of the photoplethysmography signal can reveal some valuable information about the cardiovascular system’s health.The objective of this study is to simulate the photoplethysmography experiment considering the clinical conditions of the experiment. In this work, the obtained... 

Policies affect supply chain management in oil, gas and petrochemical industries. In this study, structural equation modeling was used to evaluate the relationship between variables in AMOS software. The findings also indicated that international policies affect different aspects of supply chain management in the following order: product realization management (coordination), customer delivery management (partnership), planning management (planning) and resource management (implementation). Finally, suggestions were made on how to find financing such as bank loans, prioritizing payments in the light of their criticality, as well as on the creation. This study aimed to investigate the impact...