Sharif Digital Repository

In this thesis, we study the role of cooperation and security in multi-user channel from an information theoretic point of view. First, we review the wiretap channel as a fundamental model for the study of confidentiality in information theoretic security. To do this, we first introduce two measures for measuring the level of secrecy of confidential message, namely, average equivocation rate (AER) and equivocation rate in probability (ERP). By using a new proof, based on random covering, we show that the capacity-equivocation region of wiretap channel under AER and ERP is the same. To study cooperation in multi-user channel, we introduce the cooperative network in which each user can... 

In this dissertation we discuss various results presented in the literature on single user channels with causal or noncausal side information and multiuser channels with side information such as multiple access channel and broadcast channel. The Series Relay Networks (SRN) with delays, with and without channel state information (CSI) are investigated from an information theoretic point of view. For SRN with unlimited look ahead where the relays can use the whole received block to encode, upper and lower bounds on the capacity are derived which are tight for the degraded case. For SRN without-delay where the relays have access to the present received symbols in addition to the past symbols,... 

Concerning the variety of existing buildings and the diversity in the factors which affect the behaviors of structures, subjected to earthquakes, presenting a definite method for studying their seismic vulnerabilities has not been realized yet. Selecting a method which covers all mentioned necessities is extremely wide and complex. From one side, the capacity of structural system should be determined based on its strength and deformability. On the other hand, the nonlinear behavior of structure should be predicted by selecting the probable effects of earthquake on the region. Then, the force or acceleration which causes damage of structure's components, and the whole structural system,... 

The main purpose of this thesis is to establish the relationship between Orlicz-Hardy inequalities on a bounded Euclidean domain to certain fatness conditions on the comple-ment. Suppose Rn is a bounded domain and let d(x) := dist(x; @). We consider integral Hardy inequalities 8u 2 C1
0 ( ) Z ju(x)jd(x) C Z (jru(x)j)dxand norm Hardy inequalities8u 2 C1
0 () ju(x)jd(x) Cjkru(x)kj where : [0;1) ! [0;1) is a Young function and jk kj is representation of Luxemburg norm. Also the concept of fatness is introduced by concept of capacity  

In this thesis, the effect of cognition in wireless networks is studied. In a wireless communica-tion network, cognition is the ability of a device to sense the transmissions of neighboring nodes and adapt its own transmission to the sensed environment. Cognitive radios are very attractive be-cause of the increasing need for more efficient use of frequency spectrum. The goal of this thesis is the analysis of cognitive radio networks from an information theoretic perspective and to this end statistical models of the wireless medium with a limited and tractable number of devices are uti-lized. We consider three different models in three parts of the thesis. First, we consider a new... 

Estimation of physical parameters for solutions and mixed liqids are used widely in industrial applications. However, we can do these measurements with conventional laboratory analysis, but we always want to find an easy and quick method that use on-line measurements. In this study electrical properties of different water liquids and mixture samples in frequency stepwise range of 100-100000 Hz are measured by using a short cylindrical capacitive sensor and a measuring module (LCR-703).Operation of the capacitance measurement module for such probes is based on the auto-balancing bridge method.The effects of frequency and volume fraction on the electrical parameters and permittivity of mixed... 

For any country, the road system is an important part of its infrastructure which can affect economic development. A good level of service for a road system requires implementation of work zone projects to maintain it which usually close one or more of the lanes available for traffic. Lane reductions could cause a disturbance to normal traffic flow and speed reductions, further resulting in a reduction of road capacity and an increase of traffic delay. In addition, work zone capacity and traffic delay are the two critical indices to determine whether the effectiveness of traffic control systems is acceptable or not. Hence, the accurate estimation of capacity and traffic delay in work zones is of... 

In this thesis, we study the observability and stability problems of networked control systems (the control systems which communicate through communication channels) to answer two important questions about different system models. The first is that what is the constraints implied by the stability or observability of systems? (necessary condition on the observability and stability). The second is that under which constraints can we present a design for system to guarantee the observability or stability of systems? (sufficient condition on the observability and stability). Clearly, an efficient design is the one that presents a tight sufficient condition.One of system models addressed in this... 

One of the most important characteristics of us humans is that we are homofaber beings, and with the help of technology we transform our living conditions, and perceptions of ourselves and the world. Technology, then, plays and important role in all branches of philosophy, and especially in philosophy of science. Without, technological instruments, little scientific research can be found that can be accomplished. Many of the processes involved in scientific researches, such as experimentation and measurement, are rooted in technology. This thesis aims to examine how technology impacts science. Philosophers and historians of science have usually paid little attention to the influence of... 

Many of the existing or under-construction buildings in Iran and the world belong to masonry materials buildings. These buildings are more popular among owners and employers in non-urban, rural, and small towns than in large metropolitan areas. In addition to residential buildings, current schools and office buildings in Iran have been built or are being built using this building system. The most important factors in acceptance of these building systems are economic matters, availability of materials, simplicity of production technology of building blocks, and lack of any dependence on skilled technical personnel to build these structures. Experiences of past earthquakes show the very...