Sharif Digital Repository

Nowadays, there is a focus on developing a propulsion system with higher efficiency and performance in comparison to conventional systems. Many diverse systems have been designed for the vessel propulsion and everyday, utilizing new ideas, their performance and energy consumption are being improved. Direct use of steam energy is a noble and new idea. In this research, the steam jet propulsion system has been explained and current worldwide research on the topic has been investigated. Considering the shortage of primary data in the field and the novelty of subject, required information for the manufacturing of a sample model of this special propulsion system has been gathered and a design for... 

Government intervention in markets may go beyond the market regulation. Interventions may cause some idiosyncratic price distortions. It means the relative prices of factors to become different among firms. Therefore, micro conditions for firms will be changed. These will result in misallocation of factor production between firms and change in manufacturing TFP. According to data from about 14000 medium and small industrial firms in Iran, removing misallocation of production factors (capital and energy) and output idiosyncratic distortions between industrial firms would result in 115 percent increase in manufacturing TFP.

 

The aim of this research was estimation of investment-specific technological change, using industrial database which is published annually by Bureau of Statistics of Iran. Investment-specific technological change is the quality improvement of investment in capital goods during the time. Before estimation of this rate, production function (regarding 130 industrial activities and during 14 years, 1994-2007) was estimated. All industries classified in 4 groups based on the level of technology used in them. Then factor’s production elasticities were compared between different groups of industries. The results showed that in high-tech industries the elasticities of skilled workers, import and... 

Decision making is one of the most critical issues in engineering field. The Axiomatic Design is recently known as one of the most robust tools for decision making task. Axiomatic design is a engineering theory that provides a systematic framework for decision making using two axioms. These two axioms called Independence and Information axioms are both used to do the task.In this thesis, the information axiom is used to select the best machine (operation) for manufacturing cylindrical parts. To do that, three criteria including surface roughness, dimensional accuracy and cost have been chosen.Finally a comparison to the result of this methodology and the result of Analytical Hierarchy... 

Inappropriate effects of fossil fuels and conventional power generation systems on the environment have necessitated a sustainable energy system for the next decade by growing interests in renewable energy systems. The world’s most fast-growing renewable energy resource is the wind energy. The main problem of wind power is the power fluctuations at the load side caused by the variable nature of wind speed, and the main issue in case of remote locations is the long-term storage of power generated by wind turbines. Batteries can be used to store a limited amount of energy for a short time. Although new advances in this field have been achieved, most common type of batteries is hardly able to... 

The synergy of fundamental factors like changes in governmental policies, global expansions of the manufacturing industries and improvements in technology related to reliability of manufacturing information flow have created the global manufacturing revolution in the first years of the twenty-first century. The concept of global manufacturing enterprise potentially brings up benefits and opportunities for today’s manufacturing enterprises like reduction of manufacturing costs by utilizing low labor-cost countries, reduction of business risks and introduction of new markets as a new source for enterprise growth. However, it enforces enterprise to endure costs to adopt the global... 

In the domain of manufacturing, computer numerically controllers (CNC) technology is a major contributor to the production capacity of the enterprises. The advances in CNC technology coupled with enhancements in computing systems have provided the basis to re-examine the way in which computer-aided systems (CAx) can be used to enable global manufacturing. Interoperability of the various components of the CAx chain is therefore a major prerequisite for manufacturing enterprises for becoming strategically agile and consequently globally competitive. Being interoperable, resources can be utilized interchangeably in a plug-and-produce manner. Over the last 8years the eminence of a STEP... 

In the process of industrial and economic development and in the competitive environment in the world, reducing the cost of industrial products is an important factor for more customers' satisfaction, more revenue acquisition, and stability and success in the business. Cost engineering is the area of engineering practice concerned with the application of scientific principles and techniques to problems of cost estimating, cost control, business planning, management science, profitability analysis, project management, planning and scheduling. In this research through the studying the structures and models of cost engineering, in addition to consider this dimensions of cost engineering, the... 

This study discusses about mass customization and optimization of supply network in which both goal considering to set the flow of raw material and final product to satisfy the customer demand. The mass customization is more important concept in this study, so that this goal is placed to the first objective. In this research, the model which contained both goal is presented. The model focus on mass customization and try to satisfy various products demand, which constitute 3 kind of speed demands. Each product can satisfy in 3 way: fast, normal, slow.In the first model the new approach present in which the speed affects all of supplying, manufacturing and distributing system. The system try... 

Today in many industrial sectors, technology has made significant progress. Investing in advanced manufacturing technologies, especially computer integrated manufacturing systems is essential in order to survive in a competitive environment, improve performance, response to demand fluctuations and increase customer satisfaction. With available technologies and systems in computer integrated manufacturing (CIM) and its related technologies, the application of CIM in manufacturing enterprises is a reality and can meet the need of complicated manufacturing environment. Implementation of these systems brings many tangible and intangible benefits. But, according to several factors that must be... 

Cellular Manufacturing System (CMS) is one of the most practical manufacturing systems based on the Group Technology (GT) concept. In this thesis, a CMS is evaluated and analyzed through the proposing new mathematical models. A cellular manufacturing system includes four main sub-problems; Cell formation (CF), Group Scheduling (GS), Group Layout (GL) and Resource Assignment (RA). In this paper two problems of CF and RA are studied and discussed.At first, a new mathematical model is proposed for a CF problem. The objectives are the minimization of inter-intra cell part trips, machine breakdown cost, tool consumption cost and the reconfiguration cost. Multi-functional machines unreliability is... 

Additive manufacturing (Simply called A.M.) is a group of manufacturing technologies that is developing rapidly and is being used widely in some industries like car manufacturing, Aerospace and producing Biomedical devices, In a way that some researchers believe that A.M. methods will change the future of manufacturing. One of the most important A.M. techniques is the Selective Laser Sintering (SLS) method that is mostly used in industrial applications. A SLS machine has a lot of sub systems and mechanisms that have key role in the Laser Sintering process. One of the mechanisms of SLS machine is the Powder Dispensing mechanism that produce layers of unsintered powder as thin as 100 microns... 

Nowadays, the manufacturing environments have been faced with the globalization paradigm. This paradigm urges the new necessities for manufacturing environments like concentration on customer demands, focus on increase of quality and its continuous improving trend and shortening the products’ lifecycle. These necessities have been considered by many researchers and have led to different ideas in the field of effective and efficient product development and after sales services. Computer Integrated Manufacturing (CIM) is known as the major research field for study, development and proposal of effective IT solutions to fulfill the aforementioned necessities. This research filed has resulted to... 

Time based competition is considered as an importance strategy in the contemporary manufacturing systems. Reconfigurable Manufacturing System (RMS) is a new paradigm that not only produces the products with high productivity but also allows for rapid response to market changes. Despite the large impact on company performance, the importance of due date setting and order planning processes and related decisions is underexposed in the literature of RMS. The most important contribution of this thesis is orders planning under setting due date in make-to-order RMS environment. This thesis seeks to determine the best selection of several orders, their sequencing and corresponding configurations... 

Selective Laser Sintering (SLS) is one of the powder-based Additive Manufacturing (AM) technology in which parts built by CO2 laser. In this research work, Titanium-PMMA-Stearic Acid powders are mixed together to produce parts by Indirect Metal Laser Sintering (IMLS) method. The optimum process parameters such as energy density, Percentage composition of Titanium-PMMA and Scan Sintering are obtained by adopting the Taguchi method for getting the maximum density and minimum porosity. Experiments are planned by Taguchi’s Mix-L8 orthogonal array. According to the results obtained from this study, the percentage of combination Ti-PMMA and Energy density, respectively, are a major parameters that... 

One of the most important manufacturing methods using technologies AM, is the SLS method. This method because it would significantly reduce the construction time is the ability to build a variety of materials, is pervasive. The SLS devices input is part CAD file which is then part layered, a layer of powder is poured on the bed. Each layer is defined contour on the part and then scanned by laser inner layer is hatched by laser. Scanning algorithms and hatching in the SLS is an important part of building that has an impact on properties part and a lot of research has been done about it. synthetic scan algorithms presented in this study. The purpose of this algorithm is that part warpage and... 

Right now, the common standard for programming of CNC machines is ISO6983 which is also called G-code. This standard provides very low level information that only contains information about basic measurements and tool movements. Moreover, it splits the CAD/CAM/CNC chain and makes it difficult to gather feedback from shop floor. A global attempt led to development of a new data model for programming CNC machines. STEP-NC standard which is developing based on STEP is aimed to resolve shortages of G-code. The STEP-NC based controllers, can be categorized into three major groups in terms of programming: indirect, interpreted and adaptable. In this project, in order to develop the third category... 

The downscaling of feature size and higher process variation in COMS nano-technology are anticipated to introduce higher manufacturing anomalies. On the other hand, designs are getting more complicated due to more innovative applications where they need higher numbers of transistors. Because of these issues, integrated circuits manufacturing has become more complicated than before. Complexity in manufacturing process increases the probability of the defects in chips. This phenomenon reduces the fabrication yield. Conventional methods like fault tolerant techniques, defect tolerant techniques and redundancy are not separately good enough for improving manufacturing yield. On the other hand,... 

Dental implants should be biocompatible. This ability cause bone growth beside implant and increases stability of implant. Manufactoring method and materials used in implants are main parameters affectig biocompatibility of implants. Fabrication of functionally graded structures is a novel method to increase biocompatibility. Stress shielding is one of the main causes of failures in current dental implants. This phenomenon takes place due to different young modulus of dental implants and host bone. Pouros structures remedial this problem and implant’s young modulus comes closer to host bone. The aim of this project is to study feasibily of fabrication of functionally graded titanium dental... 

The thesis attempts to investigate one of the factors influencing enterprise innovation, namely, innovation cooperation, its types and its diversity by using the data of about 2,500 companies in different fields of industry of national innovation survey that had been collected in 1395 hijri. In this research, firstly, by reviewing the literature on the field of innovative cooperation and the performance of enterprise innovation, the model of the association of colleagues with innovation performance has been extracted. In the following, it answers to this question is whether the cooperation with colleagues is essentially affecting the innovation performance of Iranian firms or not? The...