Sharif Digital Repository

Higher-order effects in three-wave resonant interaction of a surface wave, with a pair of interfacial waves in a two-layer fluid, are studied theoretically. Following an initial rapid growth, the interfacial waves approach a steady state of constant amplitude. An explicit solution is presented for transition to the ultimate state of the interaction. It is shown that for interaction in a wave flume, it is necessary to include a 2nd pair of the interfacial waves, resulting from a reflection of the original pair in the analysis. The effects of different parameters on the dynamics of the interaction are investigated. The results indicate that a faster initial growth does not necessarily lead to... 

Fast and accurate estimation of soft error rate in VLSI circuits is an essential step in a soft error tolerant ASIC design. In order to have a cost effective protection against radiation effects in combinational logics, an accurate and fast method for identification of most susceptive gates and paths is needed. In this paper, an efficient, fast and accurate method for soft error propagation probability (SEPP) estimation is presented and its performance is evaluated. This method takes into account all three masking factors in multi cycles. It also considers multiple event transients as a new challenge in soft error tolerant VLSI circuit design. Compared with Monte Carlo (MC) simulation-based... 

In this paper, two Low cost and Soft Error Hardened latches (referred to as LSEH1 and LSEH2) are proposed and evaluated. The proposed latches are fully SEU immune, i.e. they are capable of tolerating all particle strikes to any of their nodes. Moreover, they can mask Single Event Transients (SETs) occurring in combinational logics and reaching the input of the latches. We have compared our SEU/SET-tolerant latches with some well-known previously proposed soft error tolerant latches. To evaluate the proposed latches, we have done a set of SPICE simulations. The simulation results trough comparisons with other hardened latches reveal that the proposed latches not only have more robustness but... 

In this paper, we propose two novel soft error tolerant latch circuits namely HRPU and HRUT. The proposed latches are both capable of fully tolerating single event upsets (SEUs). Also, they have the ability of enduring single event multiple upsets (SEMUs). Our simulation results show that, both of our HRPU and HRUT latches have higher robustness against SEMUs as compared with other recently proposed radiation hardened latches. We have also explored the effects of process and temperature variations on different design parameters such as delay and power consumption of our proposed latches and other leading SEU tolerant latches. Our simulation results also show that, compared with the reference... 

time-optimal problem for redundantly actuated robots moving on a specified path is a challenging problem. Although the problem is well explored and there are proposed solutions based on phase plane analysis, there are still several unresolved issues regarding calculation of solution curves. In this paper, we explore the characteristics of the maximum velocity curve and propose an efficient algorithm to establish the solution curve. Then we propose a straightforward method to calculate the maximum or minimum possible acceleration on the path based on the pattern of saturated actuators, which substantially reduces the computational cost. Two numerical examples are provided to illustrate the... 

Molecular dynamics (MD) simulation was used to study of mechanical properties of NiTiCu with different content of copper. It was shown that the percent composition of copper are significantly affects the stress-strain curves curve. The results showed that as the Cu content increased, the Yield Strength and Young's modulus decreased. © 2017 Elsevier Ltd  

The current study deals with the preparation and characterization of polysaccharide-based biocomposite films acquired by the incorporation of cellulose nanofiber within glycerol plasticized matrix formed by starch. The application of starch-based films is limited due to highly hydrophilic nature and poor mechanical properties. These problems are solved by forming a nanocomposite of thermoplastic starch (TPS) as matrix and cellulose nanofiber (CNF) as reinforcement. CNF is successfully prepared from short henequen fibers which consist of almost 60% cellulose by a chemo-mechanical process. TPS/CNF composite films are prepared by the polymer solution casting method, and their characterizations... 

This paper is concerned with an analysis of image processing data to identify interfacial waves at the interface between two fluid layers in a laboratory flume. The interfacial waves are excited through a non-linear resonant interaction with a surface wave traveling in a wave flume filled with a two-layer fluid. A spatial harmonic analysis is proposed to extract information about the nonlinear evolution of the constituent waves from the interface oscillation data. The analysis is capable of handling different stages of the resonance in the wave flume and gives accurate and consistent results on time variations of the wave amplitudes. Contrary to a temporal harmonic analysis, the proposed... 

As technology size scales down toward lower two-digit nanometer dimensions, sensitivity of CMOS circuits to radiation effects increases. Static random access memory cells (SRAMs) that are mostly employed as high-performance and high-density memory cells are prone to radiation-induced single-event upsets. Therefore, designing reliable SRAM cells has always been a serious challenge. In this paper, we propose two novel SRAM cells, namely, RHD11 and RHD13, that provide more attractive features than their latest proposed counterparts. Simulation results show that our proposed SRAM cells as compared with some state-of-the-art designs have considerably higher robustness against single-event... 

In this article, two soft error tolerant SRAM cells, the so-called RATF1 and RATF2, are proposed and evaluated. The proposed radiation hardened SRAM cells are capable of fully tolerating single event upsets (SEUs). Moreover, they show a high degree of robustness against single event multiple upsets (SEMUs). Over the previous SRAM cells, RATF1 and RATF2 offer lower area and power overhead. The Hspice simulation results through comparison with some prominent and state-of-the-art soft error tolerant SRAM cells show that our proposed robust SRAM cells have smaller area overhead (RAFT1 offers 58% smaller area than DICE), lower power delay product (RATF1 offers 231.33% and RATF2 offers 74.75%... 

The phenomenon of the hydraulic jump is so complex that despite considerable laboratory and prototype studies, estimation of its main characteristics in a generalized and accurate form is still difficult. The Artificial Neural Network (ANN) approach aims at limiting the needs for costly and time-consuming experiments. In this study, two ANN models, multi-layer perceptron using back propagation algorithm (MLP/BP) and radial basis function using orthogonal least-squares algorithm (RBF/OLS), were used to predict the roller length, sequent depth, and the relative energy loss of the B-jump. Based on a pre-specified range of jump parameters, the input vectors include: upstream bed slope (tan θ),... 

This paper proposes and evaluates Low-overhead, Reliable Switch (LRS) architecture to enhance the reliability of Network-on-Chips (NoCs). The proposed switch architecture exploits information and hardware redundancies to eliminate retransmission of faulty flits. The LRS architecture creates a redundant copy of each newly received flit and stores the redundant flit in a duplicated flit buffer that is associated with the incoming channel of the flit. Flit buffers in the LRS are equipped with information redundancy to detect probable bit flip errors. When an error is detected in a flit buffer, its duplicated buffer is used to recover the correct value of the flit. In this way, the propagation... 

Molecular dynamics simulation was used to study of mechanical properties of NiTi/Cu bilayer by nanoindentation and tensile testing. A comparison has been made among mechanical properties measured and plastic deformation process at different copper thickness during nanoindnetation and tensile test of the samples. Embedded atom method potentials for describing of inter-Atomic interaction and Nose-Hoover thermostat and barostat are employed in the simulation at 400 K. The results showed that as the copper film thickness decreased, the maximum load and hardness values increased during nanoindetation. Saha and Nix model is used to describe reduced young's modulus behaviour of the bilayer system... 

Molecular dynamics (MD) simulation was used to study of thermal properties of NiTi/Cu. Embedded atom method (EAM) potentials for describing of inter-atomic interaction and Nose-Hoover thermostat and barostat are employed. The melting of the bi-layers was considered by studying the temperature dependence of the cohesive energy and mean square displacement. To highlight the differences between bi-layers with various copper layer thickness, the effect of copper film thickness on thermal properties containing the cohesive energy, melting point, isobaric heat capacity and latent heat of fusion was estimated. The results show that thermal properties of bi-layer systems are higher than that of... 

In this paper, a hierarchical routing protocol for wireless sensor networks is introduced that aims at reducing the energy imbalance among sensor nodes by integrating the distance of the nodes from the base station into clustering policies. Moreover, the proposed routing protocol does not need any centralized support from a certain node which is at odds with aiming to establish a scalable routing protocol. Mobility management is a salient feature of this protocol that guarantees reliable communications between mobile and static nodes. A simulator was developed in the MATLAB environment to evaluate the performance of this protocol. Simulations on two different network configurations are used... 

In this Paper, a software-based control flow checking technique called SWTES (Software-based error detection Technique using Encoded Signatures) is presented and evaluated. This technique is processor independent and can be applied to any kind of processors and microcontrollers. To implement this technique, the program is partitioned to a set of blocks and the encoded signatures are assigned during the compile time. In the run-time, the signatures are compared with the expected ones by a monitoring routine. The proposed technique is experimentally evaluated on an ATMEL MCS51 microcontroller using Software Implemented Fault Injection (SWIFI). The results show that this technique detects about... 

Fast, accurate, and detailed Soft Error Rate (SER) estimation of digital circuits is essential for cost-efficient reliable design. A major step to accurately estimate a circuit SER is the computation of failure probability, which requires the computation of three derating factors, namely logical, electrical, and timing derating. The unified treatment of these derating factors is crucial to obtain accurate failure probability. Existing SER estimation techniques are either unscalable to large circuits or inaccurate due to lack of unified treatment of all derating factors. In this paper, we present fast and efficient algorithms to estimate SERs of circuit components in the presence of single... 

The continuous decrease in CMOS technology feature size increases the susceptibility of such circuits to single event transient SET and single event upset SEU, caused by energetic particles striking system wires and flip flops. This paper presents a novel SET/SEU-detection technique for I/O ports where different sampling times used to detect the effects of SET/SEUs. The power dissipation, area, reliability, and propagation delay of the SET/SEU-detection I/O port are analyzed by HSPICE v.X-2005.v9 simulation. The results show that this I/O port can detect all SET/SEUs, by consumption of about 113% more power and occupation of 145% more area than simple I/O port. ©2009 IEEE  

Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs. The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs. During seawater injection in carbonate formations, the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition. This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years. The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique.... 

New chemical process design strategies utilizing computer-aided molecular design (CAMD) can provide significant improvements in process safety by designing chemicals with required target properties and the substitution of safer chemicals. An important aspect of this methodology concerns the prediction of properties given the molecular structure. This study utilizes one such emerging method for prediction of a hazardous property, flash point (FP), which is in the center of attention in safety studies. Using such a reliable data set comprising 1651 organic and inorganic chemicals, from 79 diverse material classes, and robust dynamic binary particle swarm optimization for the feature selection...