Sharif Digital Repository

The increasing complexity of embedded systems has led to the integration of tasks with various degrees of criticality on a common hardware platform called a mixed-criticality system. These systems typically exploit the inherent redundancy of multicore systems to employ the fault-tolerant techniques to satisfy the required target reliability. On the other hand, the use of fault-tolerant techniques increases the time that cores are simultaneously active with maximum power, which can violate the thermal design power (TDP) and exceed the safe temperature of the chip. This activates the dynamic thermal manage- ment (DTM) technique. Some of the most well-known methods to reduce the chip surface... 

Lithium-ion batteries have the ability to store a significant amount of energy and work at high power, which has led to the wide spread of their use in various industries. In high-power applications, battery heat management increases lifespan, safety, and reduces battery power loss. In this study, the heat management of a very common and widely used 18650 battery using multi-layered phase change material has been investigated. The reason for using multiple layers is that each phase change material has its own weaknesses in addition to its advantages. It is expected that with the proper use of several phase change materials in the thermal management system, the materials will reduce the... 

Due to the technological improvement, decreasing transistor’s size and increasing demand for more processing abilities, designing and implementing multi core processors becomes a hot topic. One of the direct effects of decreasing the size is increasing the rate of power consumption in a unit area. Thus, the generated heat by the processor will be increased. Increasing the temperature could has undesired effects on the other features of the processor such as reliability, efciency, and failure rate. The problems that caused due to the high temperature in the multicore processors is not limited to the maximum temperature, but temperature fluctuations and variation between different parts of the... 

Fossil fuels provide the most needs of the world's energy, however, continues to lead to two key problems. The first problem is their limitation, and the second problem is the creation of serious environmental issues. Therefore, the need for renewable energy sources is felt more than ever.As an energy source, hydrogen is the lightest, most efficient and cleanest fuel. One of its unique properties is efficiency, the production of electricity by fuel cells through the electrochemical process, has far greater efficiency than of mechanical energy production from fossil fuels in internal combustion engines or energy production in thermal power plants. A fuel cell is a device that converts... 

In this study, three active, passive, and hybrid thermal management systems are applied to a lithium battery module with industrial specifications, i.e., Tesla battery module, and the optimal conditions are extracted. The thermal and electrochemical behavior of battery cells is modeled using the quasi-two-dimensional approach by Newman’s method. The effects of inter-cellular distance on the maximum temperature and on the temperature distribution in the pack as the target variables are thoroughly investigated. A suitable range for the above distances is then determined in order to reduce the overall cooling power and the expected thermal performance of the pack. The results of temperature... 

With new technologies, processor power density is dramatically increased which results in high temperature. Temperature has significant impact on reliability, performance, power consumption and cooling costs. This alarming trend underscores the importance of temperature management methods in system design. Recently, various research efforts have been focused on addressing thermal issues. Due to mobility, cost and size constraints and reliability requirements, the embedded systems do not warrant use of modern cooling mechanisms such as heat sink and fan. This caused the thermal issues to be more prominent in embedded domain. This study aims at introducing thermal management techniques for... 

Three-dimensional network-on-chip (3D NoC), the combination of NoC and die-stacking 3D IC technology, is motivated to achieve lower latency, lower power consumption, and higher network bandwidth. 3D NoCs reduce length of communication link and transmition delay by die stacking. However, the length of heat conduction path and power density per unit area increase as more dies are stacked vertically. High temperature results in longer propagation delay and increases the leakage power. If heat production in the chip is not managed, low cooling rate for these layers is a threat for the chip performance and reliability. To solve the thermal problems, thermal management schemes were proposed in the... 

Battery thermal management system is the indispensable part of the electric vehicles working with Lithium-ion batteries. Accordingly, Lithium-ion batteries modelling, battery heat generation and thermal management is the main focus of researchers and car manufacturers. While Computational Fluid Dynamics (CFD) has been used quite successfully for battery thermal management, CFD models can be too large and too slow for assembling in battery pack level models or vehicle models. In this research a much smaller reduced order model is developed, which is in the core is based on CFD models. Thus, without losing the accuracy, this model can be implemented in the vehicle model. The developed model... 

Embedded systems usually have severe limitations on power consumption. One of the reasons is that many embedded systems are battery operated. On the other hand, the battery is a non-linear source of energy, where the lifetime depends on how the system drains power from the battery, or in other words, the battery lifetime is dependent on battery discharge current curve. The nonlinear behavior of batteries is due to their inherent characteristics, where the rate capacity and the recovery effects are believed as the two most well-known and important factors. Also, embedded systems are usually fanless with limited cooling equipment, therefore temperature management is a prominent issue in these...