Sharif Digital Repository

The general approach to fault tolerance in uniprocessor systems is to maintain enough time redundancy in the schedule so that any task instance can be re-executed in presence of faults during the execution. In this paper a scheme is presented to add enough and efficient time redundancy to the Earliest-Deadline-First (EDF) scheduling policy for periodic real-time tasks. This scheme can be used to tolerate transient faults during the execution of tasks. We describe a recovery scheme which can be used to re-execute tasks in the event of transient faults and discuss conditions that must be met by any such recovery scheme. For performance evaluation of this idea a tool is developed. © 2007 IEEE  

The properties of colloidal nanoparticles are the key parameters in the fabrication of inexpensive solar cells based on the solution methods. In this study, Different nanostructures of CuInS2 (CIS) were successfully synthesized by a heating-up facile polyol-based method in which, polyols including diethylene glycol (DEG), ethylene glycol (EG), and glycerol (Gly) were chosen as both the solvent and the reductant. It is found that not only the indium precursor type but also the polyol solvent are greatly effective on the size, morphology and crystal phase of this sulfide ternary composition. Briefly, the heating-up synthesis using In(acac)3 in DEG and Gly media, created nano-sized particles... 

This paper presents the performance analysis of several best-known partitioning scheduling algorithms in real-time and fault-tolerant multiprocessor systems. To do this, multiple versions of tasks are executed on different processors. Both static and dynamic scheduling algorithms are analyzed. In the case of static scheduling algorithms, rate-monotonic (RM) scheduling policy is considered. In the dynamic scheduling algorithms, the scheduling policies are rate-monotonic and earliest-deadline-first (EDF). Partitioning scheduling algorithms which are studied here are heuristic algorithms that are formed by combining any of the bin-packing algorithms with any of the schedulability conditions for... 

The metropolis of Tehran, the capital and the largest city of Iran, has been affected by the phenomenon of land subsidence in the past years. Up to now, no comprehensive study has been presented on land subsidence in the Tehran metropolis. This study addresses this shortcoming through a comprehensive investigation of surface and sub-surface factors that affect the subsidence and investigates the mechanism of subsidence development in Tehran. Land surface studies involve assessing the subsidence rate by utilizing InSAR technology, tracking the urban development of the city through time, and investigating geomorphological features like the alluvial fans landforms and surface drainage.... 

A carbon paste electrode (CPE), modified with novel hydroquinone/TiO2 nanoparticles, was designed and used for simultaneous determination of ascorbic acid (AA), uric acid (UA) and folic acid (FA). The magnitude of the peak current for modified TiO2-nanoparticle CPE (MTNCPE) increased sharply in the presence of ascorbic acid and was proportional to its concentration. A dynamic range of 1.0-1400.0 μM, with the detection limit of 6.4x10-7M for AA, was obtained using the DPV technique (pH=7.0). The prepared electrode was successfully applied for the determination of AA, UA, and FA in real samples  

In this work successful synthesis of multiwall carbon nanotube (CNT) using solution combustion and chemical vapor deposition (CVD) methods are reported. Ceramic nanocomposite samples of (Al 2-xFe xO 3)-(y)ZrO 2 formula with x = 0.017, 0.034 and 0.17 and y = 0.15 were initially prepared. These were then subjected to CVD process during which the in situ reduction of iron oxide to metallic iron (Fe/Fe 3C) phase/s provided the necessary catalyst for the CNT formation. The formation of long flexible filaments with a smooth and regular surface bridging between alumina-zirconia (AZ) grains could be detected. The diameters of the formed filaments were in the range of ∼70 to ∼320 nm and length of the... 

In the present paper, the use of a novel carbon paste electrode modified by N,N'(2,3-dihydroxybenzylidene)-1,4-phenylenediamine (DHBPD) and TiO2 nanoparticles prepared by a simple and rapid method for the determination of dopamine (DA) was described. In the first part of the work, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various solution pH values and at various scan rates. A linear segment was found with slope value of about 48 mV/pH in the pH range 2.0 -12.0. The apparent charge transfer rate constant (ks) and transfer coefficient (α) for electron transfer between DHBPD and TiO2 nanoparticles-carbon paste electrode were calculated. In... 

A modified carbon paste electrode was prepared by incorporating TiO2 nanoparticles with bis[bis(salicylidene-1,4-phenylenediamine)molybdenum(VI)]. A mixture of fine graphite powder with 4 wt% of TiO2 nanoparticles was applied for the preparation of the carbon paste (by dispersing in paraffin) and finally modified with a molybdenum (VI) complex. The electrocatalytic oxidation of guanine (G) was investigated on the surface of the molybdenum (VI) complex-TiO2 nanoparticle modified carbon paste electrode (MCTNMCPE) using cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry (CHA) and chronocoloumetry (CHC). Using the modified electrode, the kinetics of G... 

Local educational institutions produce in-house English for Specific Purpose (ESP) materials according to the curriculum policies designated and developed by the Ministry of Higher Education In Iran. To this end, this book aims to be used in the Iranian setting at the tertiary level for undergraduate students majoring in Mechanical Engineering. Moreover, the style of English usage in this ESP textbook is American.
Regarding the content of the textbook, it has both thematic organizations in which the topics are relevant and includes sufficient treatment of the target language areas necessary for the students. The principle organizing approach of this textbook is theme-based. In addition,... 

The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of... 

A combination of silica chloride and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under mild and heterogeneous condition  

Free Content Selective synthesis of conjugated enynes from α-arylalkynols using LiCl-Acidic Al2O3 under solvent-free conditions  

7H-benzimidazo[2,1-a]benz[de]isoquinolin-7-one compounds were prepared in a selective manner by reaction between o-phenylenediamines and appropriate 1,8-naphthalenedicarboxylic anhydrides using acidic alumina under microwave irradiation