Sharif Digital Repository

Cache memory is one of the most important parts of the microprocessors. Caches improve performance by bringing data and instructions near the processors and decreasing the access time to data and instructions. But caches are also vulnerable to some kind of error called soft error. When an error happens in a cache, suddenly can propagate throughout the system and affect the integrity and reliability of the overall system. There are actually two types of errors in cache memories, permanent (hard) errors and transient (soft) errors. Previous studies have shown that about 92% of system reboots are initiated by soft-error occurring in cache memory. Soft-errors have two main sources, alpha... 

In the recent years, emerging vehicular ad hoc networks offer a wide variety of applications, including safety, convenience and entertainment. One of the beneficial applications in these fields is video streaming. However, according to the features like high mobility and loss of links, establishment of video streaming which requires stringent Quality of Service is a daunting task. In this thesis, the goal is introducing approaches in two levels, one for resilient video coding and the other one for network routing. For resilient video coding, the concentration is on the scalable video coding, which supports various applications for users with different requirements. The introduced approach... 

In this study it is attempted to investigate the impact of macroeconomic variables on the determination stock price in Iran.In this study it is used quarterly time series data of stock price and also macroeconomic variables including Growth of Consumer Price Index(Inflation), Iran Crude Oil Price, Exchange Rate, Gold Price, Liquidity, Money Supply and Gross Domestic Product for a period of 10 years (1381:1-1390:4). Data is obtained from monthly and quarterly reports, available on the website of the Central Bank of Iran and Tehran Stock Exchange Organization. In the analysis of the collected data, It is applied unit root tests, test for co integration, and utilize a Vector Auto Regressive... 

Video communications over mobile ad hoc networks is increasingly deployable as these networks become deployed in various applications such as disaster recovery. Error-prone nature of the mobile ad hoc networks and the vulnerability of compressed video to packet losses have brought many challenges to realize video transmission over MANETs. In this thesis, it is tried to achieve a good quality of service by resilient video coding and multipath transmission over mobile ad hoc networks. To generate error resilient video, a hybrid method is used by combining scalable video coding and multiple description video coding techniques. First, the video sequence is coded to two layers and then each layer... 

Nowadays large volume of sensitive data of organizations are stored in the databases. Thus, databases are attractive to the attackers to execute different types of attacks with different purposes. The useful information that attackers try to achieve in the preliminary steps of the attacks against the databases, is the database structure or schema. One of the popular approach to extract the schema of a database is to analyze the returned error messages from its DBMS. Hence, a solution to prevent schema disclosure via the error messages is customizing and modifying them. To achieve this goal, in this thesis, we propose a framework to handle and customize the error messages automatically and... 

This thesis deals with identification of Errors-In-Variable(EIV) models with Compensated Prediction Error Method (CPEM). In EIV model structure, noise affects both on input and output data. We introduce a method to identify linear and discrete EIV models where the conventional PEM in classical identification, has been used in. Using PEM on EIV models leads to a biased estimation. Therefore, the reason of incorrect estimationobtained from PEM in the presence of input noise is investigated and the importance of consideringthe input noise is explained. Then by introducing two modifications, we try to compensate the deficiencies caused due to the presence of input noise. First, some changes are... 

Fault occurrence is an inevitable problem in industrial plants. These faults have numerous types. Some common kinds of faults are faults in actuators, faults in system dynamics, and faults in sensors. In many cases it is not possible to change or repair the broken part immediately. On the other hand, it is not reasonable to shut-down the whole system due to a minor failure. Therefore we should take a measure to have the best output possible in a faulty plant. In this thesis we have proposed a new static compensator by which we distribute the contribution of the faulty actuator among the other ones. At the end we evaluate the method by means of simulations  

In this thesis, we consider an implicit approximation scheme for the stochastic heat equation with additive and multiplicative space-time white noise. we use the spectral Galerkin method in space combined with the linear implicit Euler method in time to simulate weak approximation error  

Quantum states are highly susceptible to noise and can lose their coherence easily. Thus, for the large-scale quantum algorithms results to be valid, it is necessary to use an error correction process to eliminate the errors. The theory of quantum error correction provides a comprehensive methodology for protecting quantum states against noise. In this theory, by adding ancilla qubits and carefully encoding, quantum states are prepared such that they can be robust to a great extent against errors. To perform a scalable quantum computation, we face an even more daunting task. If our quantum gates are imperfect, everything we do will add to the error. So the quantum error correction could be... 

In recent years, due to various reasons, such as outsourcing, hardware security and trust have become a crucial issue and confrontation with hardware Trojan has become one of the important part of it. Widespread usage of reconfiguration devices in industry, due to various reasons like low cost design and short time to market, makes these devices appealing for inserting hardware Trojan. Additionally, reconfigurable devices are susceptible to soft errors. Inserting a hardware Trojan in a system by an attacker can leak some information or even cause the system to break down. In previous works, in order to detect hardware Trojan, some methods have been proposed which impose high area and... 

To date various commercial systems were used in the gait analysis area. These systems have some difficulties for clinical use, such as being indwell, making trouble in movement and high prices. The Kinect sensor does not have problems of these systems. If the error of sensor is acceptable, Kinect sensor is a suitable choice for application in clinics. The possibility of utilization of the Kinect sensor as a gait analysis system has been studied in this research. The sensor errors in calculation of gait parameters for lower limb joints angle were computed. In previous researches the Kinect sensor error has been calculated for upper limb joints angle and the subject was standing motionless in... 

The broadcast nature of wireless communications makes the propagation medium vulnerable to security attacks such as eavesdropping and jamming from adversarial or unauthorized users. Applying physical layer secrecy approaches will enable the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers, without using any secret keys. However, physical layer security approaches are typically feasible only when the source-eavesdropper channel is weaker than the source-destination channel. Cooperative jamming can be used to overcome this challenge and increase the secrecy rate. In this thesis, the security of two-phase relaying system with multiple... 

Dynamic Random Access Memory (DRAM) has been the leading main memory technology during the last four decades. In deep sub-micron regime, however, scaling DRAM comes with several challenges caused by charge leakage and imprecise charge placement. Phase Change Memory (PCM) technology is known as one of the most promising technologies to replace DRAM. Compared to competitive non-volatile memories, PCM benefits from best attributes of fast random access, negligible leakage energy, superior scalability, high density, and operating in both Single-level Cell (SLC) and Multi-level Cell (MLC) storage levels without imposing large storage overhead. Unfortunately, density advantage of MLC PCM devices... 

Mutually coupled oscillator arrays have been considered. Detuning of free running frequencies of perimeter elements has been used in these arrays in order to steer the beam without phase shifters. Characteristic equations of transient and steady-state conditions of amplitude and phase of the elements of coupled oscillator arrays has been derived. Literature review is done in coupled oscillator arrays. Sensitivity analysis of beam pointing angle due to free running frequencies of elements in coupled oscillator arrays has been done and the various planar arrays has been compared. Sensitivity analysis of beam pointing angle due to phase error of elements in conventional phased array antennas... 

Wireless Body Area Network (WBAN) is a set of various physiological sensors for remote monitoring and controlling of the patient’s health status. Detection of anomalies, containing faults and physiological stresses, and distinguishing between them can eliminate the need for constant presence of specialists and decrease the occurrence of False Alarm Rate (FAR).A supervisory hardware platform for WBAN architecture is introduced and implemented in this thesis. The proposed architecture contains three sensors for recording of biomedical signals, heart rate, SpO2 and body temperature simultaneously and transmitting them to central node wirelessly through Wi-Fi standard. This proposed architecture... 

Exchange-Traded Funds (ETFs) have become an important innovation in the financial markets nowadays. They are low cost products designed to pursue different replication strategies that respond to investor’s demands of liquidity and efficiency. However, they suffer from tracking errors and price mismatches even when they are designed to avoid them. So this problem makes diffrence between return of these ETFs and Index return that will be called “Tracking Errors”. In this research, due to analysis on 7 ETFs in Tehran Stock Exchange (TSE) in the 20 months period and analysis on 8 different independent variables that was expected to affect on tracking errors, it has been showed that between four... 

Recent advances in VLSI technologies have enabled current silicon dies to accommodate billions of transistors in the design of very complex System-on-Chips (SoCs). To address the resulting complexity, Network-on-Chips (NoCs) have emerged as a paradigm to design scalable communication architecture to connect the processing cores of an SoC. However, smaller feature sizes, lower voltage levels and higher frequencies in Deep Sub-Micron (DSM) technologies make NoCs highly susceptible to transient faults, e.g., crosstalks, particle strikes, electro-magnetic interferences, and power supply disturbances. Single Event Upsets (SEUs) caused by high energy particle strikes as well as crosstalks are the... 

white noise or an innovation process through an all-pole filter. Applications of these processes include speech processing, RADAR signals and stock market data modeling. There exists an extensive research material on the AR processes with Gaussian innovation, however studies about the non-Gaussian case have been much more limited, while in many applications the asymptotic behavior of the signal is non-Gaussian. Non-Gaussian processes have an advantage over Gaussian ones in being capable of modeling sparsity. Assuming an appropriate non-Gaussian innovation one can suggest a more realistic description of sparse signals and predict their behavior or estimate their unknown values successfully.... 

In software programs, most of the time, there is a chance of error, even though they are tested carefully. Finding error-related pieces of code is one of the most complicated tasks and it can make incorrect results if done manually. Semi-automated and fully-automated methods have been introduced to overcome this issue. The rapid growth of developing smart mobile applications (SMAs) in recent years, competition among the development teams and many other factors have increased the chance of errors and hence, the quality of these applications have reduced. There are two approaches to test SMAs in order to reach a high degree of quality: (1) using existing traditional methods and adapting them... 

We study linear and semilinear stochastic evolution partial differential equations driven by additive noise. We present a general and flexible framework for representing the infinite dimensional Wiener process, which drives the equation. The equation is discretized in space by a standard piecewise linear finite element method. We show how to obtain error estimates when the truncated expansion is used in the equation. We show that the orthogonal expansion of the finite-dimensional Wiener process, that appears in the discretized problem, can be truncated severely without losing theasymptotic order of the method, provided that the kernel of the covariance operator of the Wiener process is...