Sharif Digital Repository

Residual stresses are stress fields that exist in the absence of any external loads. All mechanical processes can cause deformation that may lead to residual stresses. It is well established that virtually no material, no component and no structure of technical importance exists free of residual stresses. However, in practice, the knowledge of the true distribution of exiting residual stress is rare. The residual stress fields are very challenging to evaluate, independent of the measurement techniques. The important aspect about the residual stress determination is that often true distribution is unknown in the engineering specimen. A simple and non-destructive method to measure residual... 

The use of nanocomposite materials in various industries such as aerospace, oil and gas, automotive, etc. has become increasingly widespread due to its unique thermal and mechanical properties. Due to the problems and costs of the production process and experimental testing for optimal construction, it is necessary to propose a low-cost method for estimating the mechanichal properties of these materials. In this research, the mechanical properties of polymetric nano carbon nanocomposites have been estimated by multi-scale method with using finite element analysis by Abaqus software. the mechanical properties of nanocarbon composites have been extracted by using the multi-scale method that... 

Single nucleotide polymorphs, There are changes caused by a mutation in a nucleotide in the Dena sequence. Mononucleotide polymorphisms are the most common type of genetic variation. Some of these changes have little or no effect on cells, while others cause significant changes in the expression of cell genes that can lead to disease or resistance to certain diseases. Because of the importance of these changes and their effect on cell function, the relationships between these changes are also important. Over the past decade, thousands of single disease-related mononucleotide polymorphisms have been identified in genome-related studies. Studies in this field have shown that the expression of... 

Common privacy enhancing technologies fail to effectively hide the certain statistical aspects of encrypted traffic, namely individual packets length, packets direction and, packets timing. Recent researches have shown that using such traffic attributes, an adversary is able to extract various information from the encrypted traffic such as the visited website, used protocol or even spoken language. Such attacks in general are called traffic analysis attacks. Proposed countermeasure try to change the distribution of such features in users traffic but either they fail to effectively reduce the accuracy of that attacker or do so while enforcing a high degree of bandwidth overhead and timing... 

Process Variation is seen as statistical variations in leakage current and delay of transistors in nano-scale technologies. The amount of process variations increase as the size of transistors decrease by technology scaling such that those effects can be seen in frequency of MPSoC (Multi-Processor System-on-Chip) cores and their leakage power deviation. These variations cause the tasks duration and power consumption fluctuate in different processors in an MPSoC instance. Consequently, some chip instances of the same MPSoC may consume more time and power than their considered limitations. Hence considering the process variation is necessary and required for MPSoC optimization at different... 

Many regulations around the world use the Newmark method, directly or indirectly, in the design spectrum. Research on the Newmark design spectrum shows that this spectrum sometimes significantly differs from the earthquakes response spectra that have occurred; therefore, it is necessary to develop and introduce new design spectra by modifying the Newmark method to be more compatible with reality. The developed design spectra in seismic regulations around the world are directly affected by the records involved in their development. Thus, the appropriate design spectrum should be prepared based on the seismic characteristics of the faults of each country. Evaluation of the Iranian Seismic... 

Internal corrosion is one of the most common defects in pipelines. In recent decades, the use of offshore natural oil and gas resources has increased dramatically, followed by the use of offshore pipelines to transport products. At the same time, numerous accidents and explosions in offshore pipelines and their economic and environmental consequences underscore the importance of ensuring safe operation. Pipeline integrity management has been developed to ensure the safe and correct operation of pipelines. Integrity management starts with planning, then leads to inspection, then evaluation, and finally to corrective action, and this loop is repeated regularly. In this loop, the importance of... 

Auxetic materials have a negative Poisson ratio (NPR), which is their most distinguishable characteristic as compared to regular materials. Test specimens were made of conventional polyurethane (PU) foams according to ASTM ; then, with a thermo-mechanical process, the foam was converted to auxetic PU foam. The reproducibility of specimens' fabrication was checked with CoV= for the final foam thickness. With regard to the fact that changing loading conditions can vary Poisson's ratio, in this study, the variations occurred in Poisson's ratio due to changing loading conditions are investigated. The applied strain and strain rate were altered in experiments and statistical analysis was... 

Knee pain and injuries are very common in athletes. Anterior cruciate ligament (ACL) injury is one of the most important reason of knee acute and chronic pains. As ACL plays a significant role in knee stability and due to amount of reported ACL related injuries, much effort has been placed on finding proper and on time diagnosis and treatment of these injuries. Arthrometric methods are the most non-invasive reliable diagnosis option; however they are not fully capable of separating partial injuries from intact joint. This weakness can be investigated by quantifying the tests using computer simulations; so far few studies have been conducted toward this goal. In this study a two dimensional... 

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... 

With the increase of competition in the world of business and the advent of modern technologies, many companies in the world have turned into integration. The need for flexibility, reduction of costs, establishing close and broad connection among suppliers, producers, and distributors has caused companies to integrate their own systems and organizations so as to survive and keep going in today’s competitive, ever changing environment and finally gain competitive advantage. Supply chain management as a support for essential and operational processes of the organization is not an exception from this integration rule. Despite many views on the integrity of the supply chain, yet there is no...