Sharif Digital Repository

The aim of this paper is to design an inertial navigation system (INS) for use in a geometry pipe inspection gauge, capable of measuring pipeline movements and producing the line's 3D map with a reasonable accuracy. A suitable reference path was generated as a design platform. Solving the navigation equations and compensating for the errors, by using extended Kaiman filter (EKF) approach, the INS path was generated and its position errors in all three directions were considered. Divergence problems due to far apart GPS position observations, was overcome by defining suitable threshold for the variances of the estimated errors. Copyright © 2007 by ASME  

This paper presents a circuit level soft error-tolerant-technique, called RRC (Robust Register Caching), for the register file of embedded processors. The basic idea behind the RRC is to effectively cache the most vulnerable registers in a small highly robust register cache built by circuit level SEU and SET protected memory cells. To decide which cache entry should be replaced, the average number of read operations during a register ACE time is used as a criterion to judge. In fact, the victim cache entry is one which has the maximum read count. To minimize the power overhead of the RRC, the clock gating technique is efficiently exploited for the main register file resulting in... 

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... 

The three-dimensional supersonic turbulent flows over wrap-around fin missiles have been computed using the Thin Layer Navier-Stokes (TLNS) equations to reduce the computational efforts compared to those of the Full Navier-Stokes (FNS) equations. In this research, the missile configuration is divided into multi regions to enable fluid flow simulation using Personal Computers (PC). It also makes it possible to use a different number of nodes and distribution of grids in each region to enhance the accuracy. The Thin Layer Navier-Stokes equations in the generalized coordinate system were solved using an efficient, implicit, finite-difference factored algorithm of the Beam and Warming. For the... 

This paper presents a low cost fault-tolerant technique so called OWHR (Operand Width Aware Hardware Reuse) to ALU design in embedded processors. The OWHR technique is motivated by two facts: (1) Many of the produced and consumed values are narrow-width values in the embedded processors, i.e. they have leading zeros or ones in their most significant bits. This indicates that only a fraction of the circuit is performing useful operations when a particular arithmetic or logic circuit in the ALU is operating on narrow-width values; (2) other circuits of the ALU are not used, when a particular arithmetic or logic circuit is being utilized to perform a specific operation in the ALU in the... 

Single event upsets (SEUs) and single event transients (SETs) are major reliability concerns in deep submicron technologies. As technology feature size shrinks, digital circuits are becoming more susceptible to SEUs and SETs. A novel SEU/SET-tolerant latch called feedback redundant SEU/SET-tolerant latch (FERST) is presented, where redundant feedback lines are used to mask SEUs and delay elements are used to filter SETs. Detailed SPICE simulations have been done to evaluate the proposed design and compare it with previous latch designs. The results show that the SEU tolerance of the FERST latch is almost equal to that of a TMR latch (a widely used latch which is the most reliable among the... 

The continuous decrease in CMOS technology feature size increases the susceptibility of such circuits to single event upsets (SEU) caused by the impact of particle strikes on system flip flops. This paper presents a novel SEU-tolerant latch where redundant feedback lines are used to mask the effects of SEUs. The power dissipation, area, reliability, and propagation delay of the presented SEU-tolerant latch are analyzed by SPICE simulations. The results show that this latch consumes about 50% less power and occupies 42% less area than a TMR-latch. However, the reliability and the propagation delay of the proposed latch are still the same as the TMR-latch. the reliability of the proposed latch... 

This paper presents a cost-efficient technique to jointly use circuit- and architecture-level techniques to protect an embedded processor's register file against soft errors. The basic idea behind the proposed technique is robust register caching (RRC), which creates a cache of the most vulnerable registers within the register file in a small and highly robust cache memory built from circuit-level single-event-upset-protected memory cells. To guarantee that the most vulnerable registers are always stored in the robust register cache, the average number of read operations during a register's lifetime is used as a metric to guide the cache replacement policy. A register is vulnerable to soft... 

Hybridization of conventional vehicles is considered an important step to achieve high fuel economy and low emissions. In this study, principle considerations involved in a hybridizing process are discussed and consequently, a sequential approach for designing hybrid components for both series and parallel configurations has been introduced. The so called approach has then been applied to one of the productions of Iran-Khodro Company called SAMAND. Having designed the hybrid components, the conventional SAMAND and its series and parallel hybrid configurations were defined and evaluated using the ADvanced VehIcle SimulatOR (ADVISOR) software. It is observed that compared to the conventional... 

In this paper a fuzzy power controller for a parallel hybrid passenger car is developed in order to minimize its fuel consumption and optimize its components efficiencies. This is done by controlling the engine operating points in its optimal region and maintaining the SoC of batteries and electric motor operating point at the highest possible efficiency. Of course the designed control strategy must be able to obey the driver's commands and achieve the PNGV regulations. The controller implemented in this paper is a Mamdani fuzzy logic controller which takes the batteries SoC, electric motor's speed, ICE speed and the total demanded torque as its input variables and gives the ICE torque as... 

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... 

Workspace of a mechanism is generally defined as the region of space which end-effector of that mechanism can reach. Determination of workspace is an important task in the design of a mechanism. However, for parallel mechanisms, due to the complexity of solving the forward kinematic equations, determination of workspace is much more complicated than for serial mechanisms. In the literature, time-consuming numerical methods, such as point-by-point searching, are usually employed for this purpose. In this paper, an optimization-based algorithm is introduced for the boundary determination of inclusive and constant orientation workspaces of parallel mechanisms. In the proposed algorithm, thanks... 

Motivated by recent laboratory and field observations, this paper reports the first quantitative measurements of the stabilization phase of interfacial instability in a two-layer fluid in surface wave motion. The instability results from the formation of a resonant triad between the surface wave and noise-level sub-harmonic interfacial waves. To exclude the effects of interfacial mixing on the interaction, the experiments were carried out with immiscible fluids. Carrying out a resonant interaction analysis to the third order of nonlinearity using a Lagrangian formulation, we also show for the first time that the three-wave resonance is inherently accompanied by a harmonic four-wave resonant... 

The resonant interaction of surface and internal waves produces a nonlinear mechanism for energy transfer among wave components in oceans, lakes, and estuaries. In many field situations, the stratification may be well approximated by a two-layer fluid with a diffuse interface. The growth and damping rates of sub-harmonic interfacial waves generated by a surface wave through a three-wave resonant interaction are measured in the laboratory. These measurements are compared with theoretical predictions. A diffuse interface reduces the damping rate and increases the growth rate. The predicted growth rate provides excellent comparison with the laboratory measurements. The inclusion of the effects... 

We demonstrate that Markov processes play a fundamental role in probing rough surfaces and characterizing their topography. The surface topography obtained by a probe, as in the atomic force microscopy (AFM) technique, is based on the probe-surface interactions. When the size of the probe tip is comparable with the height of the surface fluctuation, the surface image can be aberrated from its origin. Due to the tip effect, there is a crossover in the structure function of the surface. For scales smaller than the Markov length -the minimum length scale over which a process is Markovian - the stochastic function that describes a rough surface is non-Markovian, whereas for length scales larger... 

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  

Two-dimensional (2D) electron systems in the presence of disorder are of interest in connection with the observed metal-insulator transition in such systems. We use density functional theory in its local-spin density approximation (LSDA) to calculate the ground-state energy of a 2D electron system in the presence of remote charged impurities which up on averaging provides disorder. The inverse compressibility calculated from the ground-state energy exhibits a minimum at a critical density controlled by the disorder strength. Our findings are in agreement with experimental results. © World Scientific Publishing Company  

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...