Sharif Digital Repository

Scheduling of real-time processes is often one of the greatest challenges in designing distributed embedded systems. Low energy consumption and fault tolerance are key objectives in the design of embedded systems. However, these objectives are at odds, and there is a trade-off between them. A large part of this thesis includes a comprehensive study on previous researches on energy consumption and fault tolerance in hard real-time embedded systems. Real-time systems usually use system level energy management methods, i.e., dynamic voltage scaling (DVS) and dynamic power management (DPM). Also hard real-time systems often use replication to achieve fault tolerance. In this thesis, we... 

Information Theory, as an important part of communication theory, tries to find inner and outer bounds for reliable rate of information transmission in communication networks. In Network Information Theory, It is usually assumed that the channel statistics is known to everyone. However, in some practical situations, we might not know the statistics. The compound channel and the arbitrarily varying channel (AVC) are two categories of models which have considered this problem. In this thesis, in order to have a more general model regarding information transfer in the presence of channel uncertainty, we propose a model which is essentially a combination of compound channel and AVC. In our... 

A predefined assumption in many learning algorithms is that the training and test data must be in thesame feature space and have the same distribution.However, this assumption may not hold in all of these algorithms and in the real world there might be difference between the source and the targer domian, whether in the feature space or the distribution. Moreover, there might be a few number of labled data of the target domain which causes difficulty in learning an accurate classifier. In such cases, transferring knowledge can be useful if can be done successfully and transfer learning was introduced for this purpose. Domain Adaptation is one of the transfer leaning problems that assume some... 

Usually, in information theory, the length of the message (number of bits of information) is proportional to the number of channel uses, for example, in traditional channel coding, the number of messages is $ 2 ^{NR} $ and $ NR $ bits with $ N $ channel uses were sent. In fact, as the channel uses increase, the message bits increase linearly. But in this dissertation, the length of the message, or indeed the number of source observations, is a function of the number of channel uses.In this dissertation, we first study the problem of designing the best code for a discrete Poisson channel with memory (under peak-power and total-power constraints). The outputs of a discrete Poisson channel with... 

In this work, we consider a zero error coordination problem wherein the nodes of a network exchange messages to be able to perfectly coordinate their actions with the individual observations of each other. While previous works on coordination commonly assume an asymptotically vanishing error, we assume exact, zero error coordination. Furthermore, unlike previous works that employ the empirical or strong notions of coordination, we define and use a notion of set coordination. This notion of coordination bears similarities with the empirical notion of coordination. We observe that set coordination, in its special case of two nodes with a one-way communication link is equivalent with the “Hide... 

One of the main challenges in data transmission is synchronization error. In practice there are solutions to this issue, but this incurs a cost that can not be neglected. Synchronization error consists of deletion, insertion and substitution. Investigation of such errors in a communication channel has been of a great concern in information theory. Furthermore, in many applications such as biology and data storage on disks, we observe synchronization errors. Deletion channel is defined as a channel in which input symbols are deleted with a probability d independently of each other, such that the order of symbols remains unchanged. In spite of attempts to find a closed form for the capacity of... 

The goal of the research presented in this thesis is assessment of millimeter-wave (mm-wave) reflectometry as a potential method for non-invasive detection of skin cancers. The reasons for choosing mm-waves are lower penetration, higher resolution and technology maturity. The main work of this research is numerical simulation of reflection from skin and other media as well as reflection measurement of some skin-equivalent phantoms at mm-wave frequencies. By exposing the skin to mm-waves and studying the characteristics of the reflected wave malignant lesions are differentiated from benign and normal skin tissues. Since Oxygen molecules have strong attenuation peaks around 60 GHz band, this...