Sharif Digital Repository

Soft-errors are increasingly considered as a major cause for computer system failures. Software techniques are used as cost-effective and flexible techniques to tolerate soft-errors but the introduced overhead is not acceptable in some safety-critical real-time systems. The identification of the program blocks and protecting only vulnerable blocks against soft-errors reduces the performance overhead. In this paper, we present a genetic algorithm to identify the vulnerable program blocks as well as the derating program blocks against soft-errors. Then, only vulnerable blocks are protected by some software-based soft-error tolerance techniques to achieve a lower performance and space overhead.... 

In this paper, an algorithm for positioning error reduction of a low-cost global positioning system (GPS) receiver for kinematical applications has been proposed. Proposed algorithm is mainly based on determining jittered data points (outliers) in the data file based on the correlation among positioning data in three different directions. The main point of applicability of proposed algorithm for kinematical applications is aforementioned correlation. The proposed algorithm and a recursive averaging algorithm has been implemented and tested on the output raw position data collected from a low-cost GPS receiver. Experimental results demonstrate the superior performance of the proposed... 

In this paper we study the statistical properties of the Signal to Noise Ratio (SNR) of the dual-hop relaying link in a cooperative wireless communication system in the presence of channel estimation errors for Decode and Forward (DF) relaying protocol. Then for assessment of the system performance the Symbol Error Rate (SER) is considered. Two approaches are introduced for SER calculation from which the second one results in a closed form solution. Finally the second approach is used to find an optimum power allocation scheme for transmission of pilot and data symbols at the source and the relay terminals that results in minimizing the SER and considerable amount of power saving. Also Monte... 

In the present research, human errors existed in tasks of operators working in two control rooms (Northern and Southern control rooms) in the Tehran oil refinery are identified and evaluated. Then, corrective strategies and actions are advised to decrease errors. At first, using hierarchical task analysis (HTA) method, four positions including shift controller, head operators, control room's operators, and outside operators are analyzed. Afterwards, human errors in the considered positions are identified and assessed using technique for retrospective and predictive analysis of cognitive errors (TRACEr). Results present 670 internal errors and 738 external errors in the Northern sector while... 

Scratchpad memories (SPMs) are widely employed inmulticore embedded processors. Reliability is one of the major constraints in the embedded processor design, which is threatened with the increasing susceptibility of memory cells to multiple-bit upsets (MBUs) due to continuous technology down-scaling. This article proposes a low-cost and efficient data replication mechanism, called In-Scratchpad Memory Replication (ISMR), to correct MBUs in SPMs of multicore embedded processors. The main feature of ISMR is a smart controller, called Replication Management Unit (RMU), which is responsible for dynamically analyzing the activity of the SPM blocks at runtime and efficiently replicating the... 

In this paper, we propose a very fast analytical approach to measure the overall circuit Soft Error Rate (SER) and to identify the most vulnerable gates and flip-flops. In the proposed approach, we first compute the error propagation probability from an error site to primary outputs as well as system bistables. Then, we perform a multi-cycle error propagation analysis in the sequential circuit. The results show that the proposed approach is four to five orders of magnitude faster than the Monte Carlo (MC) simulation-based fault injection approach with 92% accuracy. This makes the proposed approach applicable to industrial-scale circuits  

Embryogenesis, regeneration and cell differentiation in microbiological entities are influenced by mechanical forces. Therefore, development of mechanical properties of these materials is important. Neural network technique is a useful method which can be used to obtain cell deformation by the means of force-geometric deformation data or vice versa. Prior to insertion in the needle injection process, deformation and geometry of cell under external point-load is a key element to understand the interaction between cell and needle. In this paper, the goal is the prediction of cell membrane deformation under a certain force and to visually estimate the force of indentation on the membrane from... 

Positioning for kinematic applications is of great importance in terms of accuracy and computational complexity. In this paper, we present an algorithm based on correlation between error components in three directions, i.e. Δx, Δy, Δz to decrease positioning error of a GPS receiver for kinematic applications. The main feature of proposed algorithm is that it modifies data at each instant and in each direction using data of two other directions at the same instant (i.e. some sort of online modification). This feature was acquired using an approach introduced to model state transition matrix using AR coefficients of two other directions. The algorithm was implemented on the output raw position... 

In this paper, we propose a new transmission scheme, called integer forcing-and-forward (IFF), for communications among multipair multiple-antenna users in which each pair exchanges their messages with the help of a single multiple-antenna relay in the multiple-access and broadcast phases. The proposed scheme utilizes integer forcing linear receiver (IFLR) at the relay, which uses equations, i.e., linear integer combinations of messages, to harness intrapair interference. Accordingly, we propose the design of a mean square error (MSE)-based transceiver, including precoder and projection matrices for the relay and users, assuming that perfect channel state information (CSI) is available. In... 

In this study, the authors consider the designing of a new set of uniquely decodable codes for uncoded synchronous overloaded code division multiple access for the number of codes exceeding the assigned code length. For the construction, the proposed recursive method at iteration-k generates a matrix that can be classified into k orthogonal subsets of different dimensions. Out of them, all besides the largest (binary Hadamard) one are ternary in nature. There resides an inbuilt twin tree structured cross-correlation hierarchy that facilitates an advantageous balance between the auto and intergroup cross-correlation for the signatures in a subset. This opportunity is further leveraged by the... 

Some factors like environmental conditions and manufacturing errors affect performance of a MEMS rate gyroscope. Because they may result to parameter mismatch between the designed gyroscope and the fabricated one. The Parametrically excited gyros are more robust to these changes than the harmonically excited gyros. However, these types of gyros also experience reduction in their accuracy in angular velocity determination due to these changes. One of parameters that affect the accuracy of the gyroscope is quadrature error that here, its effect in the accuracy of angular velocity determination is investigated in two typically designed harmonically and parametrically excited MEMS gyroscopes.... 

Nowadays, a large volume of an organization's sensitive data is stored in databases making them attractive to attackers. The useful information attackers try to obtain in the preliminary steps, is the database structure or schema. One of the popular approaches to infer and extract the schema of a database is to analyze the returned error messages from its DBMS. In this paper, we propose a framework to handle and modify the error messages automatically in order to prevent schema revealing. To this aim, after identifying and introducing an appropriate set of categories of error messages, each error message that is returned from a DBMS is placed in a proper category. According to the policy... 

This paper deals with identification of discrete-time errors-in-variables models where the input and output data are both perturbed by different additive noises. The goal is to study the effects of input noise on the model which is estimated based on the prediction error method. The obtained model is then improved by modifying the results and implementing the instrumental variable method. It is proved that the identification of the errors-in-variables models based on the proposed approach could result in an unbiased estimation in the presence of independent colour noises on the input and output data with adequate accuracy and mediocre complexity. © 2017 Informa UK Limited, trading as Taylor... 

To date various commercial systems have been used in the GAIT analysis. These systems have some difficulties for clinical use, such as interfering with normal movement and high prices. The possibility of utilization of Kinect as a sensor for GAIT analysis has been studied in this research. The accuracy of Kinect in calculation of GAIT parameters such as lower limb joint angles, stride time, and stride length were computed during normal walking. The effects of the sensor's position and direction relative to the walkway were also investigated. The Kinect sensor was installed at different positions toward the motion path. In each position the data was recorded by both Kinect and a commercial... 

The state estimation (SE) is a fundamental data processing algorithm used by the control centers of modern power networks. The most widely used state estimator is rooted to the weighted least squares (WLS) estimator which is not sufficiently robust to the gross errors in the measurements. This paper, presents a new robust algorithm for power system SE environments. The proposed approach not only has the comparative performance of the conventional loss function based on the estimator of the WLS additionally, it also considers loss function based on the quasi weighted least squares (QWLS) estimator. The performance analysis is evaluated on the ability of the state estimator for reducing the... 

MEMS rate gyroscopes are prone to different errors because of environmental conditions and manufacturing errors. These errors can result to mismatch between the fabricated gyros and the designed ones. Different environmental conditions and disturbances can change the parameters and specifications of a gyro, and its sensitivity may deteriorate, since the parameters are different from the optimal ones. External linear acceleration is one of the main environmental disturbances that may change the behavior of an MEMS rate gyro that its effect on the accuracy of an MEMS proof mass gyroscope is found here. This is done by finding the equations of motion of gyroscope in presence of acceleration and... 

This paper deals with identification of discrete-time errors-in-variables models where the input and output data are both perturbed by different additive noises. The goal is to study the effects of input noise on the model which is estimated based on the prediction error method. The obtained model is then improved by modifying the results and implementing the instrumental variable method. It is proved that the identification of the errors-in-variables models based on the proposed approach could result in an unbiased estimation in the presence of independent colour noises on the input and output data with adequate accuracy and mediocre complexity. © 2017, © 2017 Informa UK Limited, trading as... 

Being able to track objects that surround us is key for planning actions in dynamic environments. However, rigorous cognitive models for tracking of one or more objects are currently lacking. In this study, we asked human subjects to judge the time to contact (TTC) a finish line for one or two objects that became invisible shortly after moving. We showed that the pattern of subject responses had an error variance best explained by an inverse Gaussian distribution and consistent with the output of a biased drift-diffusion model. Furthermore, we demonstrated that the pattern of errors made when tracking two objects showed a level of dependence that was consistent with subjects using a single... 

In wideband interferometric direction finding ambiguity is inevitable due to practical antenna array dimensions. A new algorithm for wideband interferometer direction finding is developed to resolve the ambiguity problem with minimum number of antennas. The method is based on direction finding by three antennas arranged at the three vertices of a triangle named the base-triangle. A two dimensional matrix of ambiguous angles is generated. The ambiguity problem is resolved by an auxiliary base-triangle formed by a fourth antenna in the arrangement. The common angle between the two ambiguous directions derived from the two base-triangles, is the desired angle. As such a four antenna array is... 

Spin-Transfer Torque Magnetic RAM (STT-MRAM) as one of the most promising replacements for SRAMs in on-chip cache memories benefits from higher density and scalability, near-zero leakage power, and non-volatility, but its reliability is threatened by high read disturbance error rate. Error-Correcting Codes (ECCs) are conventionally suggested to overcome the read disturbance errors in STT-MRAM caches. By employing aggressive ECCs and checking out a cache block on every read access, a high level of cache reliability is achieved. However, to minimize the cache access time in modern processors, all blocks in the target cache set are simultaneously read in parallel for tags comparison operation...