Sharif Digital Repository

High reliability and low power consumption are two crucial requirements of embedded systems. To do this, embedded systems exploit fault-tolerant techniques to keep reliability at a guaranteed level and power management methods to reduce power consumption. However, the inherent redundancy of the fault-tolerant techniques increases the power consumption and, consequently, the system temperature, which leads to an increase in the rate of the aging phenomenon. Power management methods increase the system's lifetime by reducing the system temperature. However, some power management methods (e.g., Dynamic Voltage and Frequency Scaling) increase the fault rate. Recently, heterogeneous multicore... 

Iran have experienced tangible demographic changes over the recent decades. Fertility rate and marriage rate have declined, but divorce rate has increased remarkably. This research intends to examine the propensity to marry and marriage age in Iran by use of Household expenditure and income survey data (2009-2012) in the framework of search and match model. In the underlying literature, some socioeconomic factors are identified as the main determinants of these changes, particularly labor market prospects and male’s earning structure are considered as the most significant factors among others.The data are pooled and for the study years are merged with cohort data from the labor market to... 

The manufacture of ultra high strength materials has always been a target for aerospace and transportation industries. Currently, the limitation of energy resources even makes this goal more serious. Nowadays, more than 50% of total extrusion products are made from Al alloys and around 90% of them are the 6000 series alloys. Therefore, regarding to high strength, low weight, and hardening aluminum AA6000 alloys capabilities can play a major role in fulfilling this task. Over the last decade, a number of techniques collectively referred to as severe plastic deformation (SPD), have emerged as a promising approach for the production of bulk ultrafine-grained (UFG) nano-structured materials.... 

In the current era, the urgent need to reduce the use of fossil fuels and limit carbon emissions has highlighted the importance of shifting from traditional gasoline-powered vehicles to electric vehicles. The evolving landscape and challenges in the field of electric vehicles highlight the importance of ensuring the safety and reliability of energy storage systems. Lithium-ion batteries play a central role in electric vehicle technology, requiring thorough research efforts. Notably, the detection of internal short circuit, a common issue in lithium-ion batteries, has become a focus of researchers in recent years. This study aims to investigate the internal short circuit fault in lithium-ion... 

Metallurgical phenomena modeling help the researchers to understand the influence and contribution of different factors on the alloys properties. One of the most interesting phenomenon is the aging process occuring in age-hardenable alloys like 2xxx aluminium series. A factor which has high impact on aging and there are not proper models for evaluating that, is the contribution of plastic deformation. This factor has contribution not only on the dynamic precipitation (during deformation) but also on the natural aging after plastic deformation. So in this research a model containing the role of plastic deformation on dynamic precipitation and the contribution of dynamic precipitation on total... 

Negative Bias Temperature Instability (NBTI) in CMOS devices is known as the major source of aging effect leading to performance and reliability degradation in modern processors. Instruction-cache (I-cache), which has a decisive role in performance and reliability of the processor, is one of the most affected modules by NBTI. Variations in duty Cycles and long-time residency of data blocks in I-cache lines (stress condition) are the two major causes of NBTI acceleration. This paper proposes a novel I-cache management technique to minimize the aging effect in the I-cache SRAM cells. The proposed technique consists of a smart controller that monitors the cache lines behavior and distributes... 

Bitumen ageing is one of the principal factors causing the deterioration of asphalt pavements. Ageing is a complex process that is affected by different parameters.With the rapid growth of modified binders in road paving applications over the past twodecades, it is important to study the ageing properties of these binders. A number of laboratory methods are used tosimulatethe bitumenageing at various stages of the production and service of hot mix asphalt.Recent studies have shown that Superpave testing protocol does not fully address the ageing of modified binders. To study the ageing properties of modified binders, three different types of binder modifiers, plastomer, elastomer, and ground... 

Combining the concept of Network-on-Chip (NoC) with three dimensional integrated circuits technology on 3D NoC enables reduction of propagation delay, interconnect power consumption, and die area, as well as increase in system operational bandwidth. Nevertheless, reducing the feature size of semiconductor technologies has raised certain aging mechanisms, like Negative Bias Temperature Instability (NBTI) and Electromigration, as the main reasons for reduction in reliability and lifetime of NoCs. Reduction in die area results in an increase in power density of the chip, which exacerbates temperature-related concerns of 3D NoCs compared to 2D NoCs. Thus, the aging mechanisms that are directly... 

Austenitic stainless steels have extensive and special mechanical properties because of austenite to α΄-martensite transformation due to plastic work. Obtaining a process path that provides maximum strength and flexibility and minimum α΄-martensite content (α΄-martensite increases corrosion current) in these steels is important in the industry. Applying the aging process after applying plastic strain (single-stage aging) results in an increase in strength of up to 200 MPa and an increase in hardness of up to 60 Vickers. However, single-stage aging does not cause significant changes in the amount of α΄-martensite in steel and in the temperature range of 400 to 500 ° C, it causes a slight... 

In this research, friction and wear behaviors of 2024 Al and 2024 Al-20 vol.% SiC composite -prepared by powder metallurgy method- were investigated in the temperature range 20- 250°C. Dry sliding wear tests were conducted at a constant sliding velocity of 0.5 m/s, an applied load of 20 N, and a sliding distance of 2500m using a pin-on-disc apparatus. Some of the wear tests were carried out with artificially aged specimens in order to determine the aging effects. Worn surfaces and wear debris were also examined by using SEM, EDS and XRD techniques. All specimens showed a transition from mild to severe wear above a critical temperature. In the mild wear regime, the wear rate and the friction... 

Transformers are vital components of power networks, responsible for converting electricity from one voltage level to another. They are designed to operate under sinusoidal conditions, but the increasing use of non-linear loads and power electronic devices has caused a spike in harmonic pollution in power networks. These harmonics result in increased losses in transformers, leading to a reduction in capacity, accelerated aging, and a shortened life. The associated costs incurred by these issues include reduced energy sales for electricity companies and premature replacement costs. In this thesis, it is assumed that the transformer is affected by harmonics and ambient temperature, and other... 

In This thesis the properties of a compatible rubber compound for a specific chemical environment (acidic media) with high temperature and high pressure (HTHP) is studied. After primary studies, six formulations are designed on the basis of Nitrile rubber. after tensile and hardness tests at ambient temperature and 120 °C, samples putted in aging reservoir for aging tests. After that, tensile and hardness tests were performed again. Finally, by analyzing the results, the best formulation have chosen. Test results show that the NBR / PVC compound with higher filler load, has the best chemical resistance  

Lifetime extension would be a necessary preventive action to halt micro cracks expansion on the airplane external surface. To decide about whether to perform this operation, one should examine technological maturity, costs and technical parameters. Technical status in lifetime extension is one of the major drivers of this decision which should be considered in the first step of technology management process which is known as the technology attractiveness step. In this research, major technologies of rejuvenation is examined and categorized by the technology mapping. Also, key processes of rejuvenation and technological fields ranking has been determined by the procedural view tools of the... 

Al-4.5% Cu alloy, an age-hardenable alloy, is an important alloy in industry due to such unique characteristics as high strength-to-weight ratio and considerable strength at elevated temperatures. In this study, the aim was to evaluate the combined effect of cooling rate and heat treatment on an A206 alloy having more impurities—especially iron—than the nominal specifications. To this end, the melt was poured in a five-step mold. Afterwards, each step was subjected to T4 and T6 treatments in order to study the changes compared to the as-cast samples. Ultimate tensile strength, yield strength, elongation, and grain size were determined by using tensile tests and optical microscopy,... 

Extensive studies have been performed on the genetic variations involved in common neurodegenerative diseases such as Alzheimer's, macular degeneration, and Parkinson's. In most cases, no specific gene has been identified pointing to a distinct pathogenic pathway, therefore, this study mainly aims to find common genes among aforementioned diseases according to determination of a specific pathogenic protein pathway.In this study, we reached a deep understanding of the function of nervous system and the discovery of causative agents of the diseases by applying the sources of information from genome datasets in bioinformatics analysis. The utilized database comprises the classification of... 

PE pipes and specially PE100 are commonly used for the transportation of drinking water, transferred water was mostly disinfected by disinfectants such as chlorine, chlorine dioxide and chloramine. Long-term contact with water containing disinfectants led to morphological and mechanical changes and followed by oxidative degradation and failure. Antioxidants are stabilizers which are used in PE pipes to postpone oxidation and increase the durability of these pipes. Migration of antioxidants is possible during the terms of service, in this case antioxidants can be washed by water and left the pipe. As a result, the loss of antioxidants decreases the stability of pipes and leads to oxidative... 

Average of females’ age in the first marriage was increasing in Iran, in the last two decade from 20.9 in 1991 To 22.7 in 2010. It is well accepted that labor market condition and the males’ wage structure are the main determinants of preference toward marriage among others. Making use of a provinces-wide panel data 1991 To 2010 and micro individualized data (Household income and expenditure survey) for all the provinces, this research aims to assess the role of males’ wage inequality in the marriage rate in provinces and the probit cross-section models of preferences toward marriage in Iran. In the frame work of search and match theory of marriage our findings reveal that wage inequality... 

To ensure stable and optimal operation of lithium-ion batteries (LIBs), it is necessary to use a management system for online monitoring and accurate estimation of battery State of Charge (SOC). Due to LIBs' complex dynamics and effective factors such as temperature and side reactions, battery SOC estimation has become one of the greatest challenges for experts in the field. In this research, an adaptive sliding mode observer has been designed and evaluated for a cylindrical lithium manganese oxide battery with a capacity of 1258 mAh. At first, rigorous simulation of lithium-ion battery has been performed by utilizing the P2D electrochemical as well as thermal and aging model to be the main... 

In this study, the solution treatment of severely deformed AA 2024-O and its post-severe plastic deformation is investigated. The investigation was performed in two cases of pre-multi directional forging (pre-MDF) and post-multi directional forging (post-MDF) on the solution treatment. After applying pre-MDF, finding kinetics of temperature and solution time caused that natural aging to be studied as a treatment after solid solution. By measuring the difference in hardness before and after natural aging in pre-MDFed and un-MDFed samples, 500℃ and 5 minutes were found to be the most desirable temperature and time in terms of mechanical properties and microstructure. Continuous... 

In recent decades, the use of modifiers has been one of the common methods on major roads to inhibit cracking and permanent deformation in asphalt pavements. Simultaneously, due to the economic and environmental benefits of hot mix asphalt recycling, the consumption of recycled asphalt pavement on all types of roads has been on the rise. However, a significant issue with recycled asphalt mixtures is their susceptibility to various types of cracking, as a result of the increased stiffness and brittleness of the recycled asphalt binders. To address this issue, two main questions need to be answered; a) the potential positive effects of modifiers left in the recycled mixture to be accounted for...