Sharif Digital Repository

The performance of degree of polarization (DOP) is investigated as a control signal in polarization-mode dispersion (PMD) compensation systems aided by polarization scrambling. The relation between the input and output polarization states of a signal propagating through a polarization scrambler and a PMD-induced optical fiber is described by a 3 × 3 Stokes transfer matrix. The average DOP of the output signal over a period of polarization scrambling is derived as an alternative to the conventional DOP-based control signal, i.e., minimum DOP. In the presence of first- and all-order PMDs, the performance of the average and minimum DOPs in monitoring of differential group delay (DGD) for... 

In this study, dissimilar friction stir welding was performed between AA5052 aluminium and AZ31 magnesium alloys using a variety of parameters. The results revealed that the optimal range of welding parameter is between 20 and 38 rpm/mm.min−1 (the ratio of rotation speed to travel speed). The findings of the X-ray diffraction and Micro-hardness tests on the stir zone indicated that when the rotation speed is increased, it leads to the formation of intermetallic compounds such as Al12Mg17 and Al3Mg2. The polarization test was used to assess the corrosion rate in various zones. The corrosion rate in the stir zone is higher than in other zones due to macro-galvanic couple between Al and Mg.... 

Two main objectives in designing real-time embedded systems are high reliability and low power consumption. Hardware replication (e.g., standby-sparing) can provide high reliability while keeping the power consumption under control. In this paper, we consider a standby-sparing system where the main tasks on primary cores are scheduled by our proposed peak-power-aware earliest-deadline-first policy while the backup tasks on spare cores are scheduled by our proposed peak-power-aware earliest-deadline-late policy to meet the chip thermal design power (TDP) constraint. These policies provide the best opportunity to shift the task executions as much as possible to minimize execution overlaps... 

One of the underlying factors in the conservation and development of urban green spaces is the available water resources use for green areas in each region. The primary purpose of this study is to introduce the integration of a proper simulation method for runoff along with AHP-PROMETHEE decision-making method for water resources management in urban basins. The application of this approach was investigated in the city Buin Zahra of Qazvin Province of Iran. In the first step by using the analytic hierarchy process (AHP), the available water resources in the case study were weighted. In the second step, the water resources of the municipal and residential wells and water collected by... 

Improving testability during the early stages of high-level synthesis has several benefits including reduced test hardware overheads, reduced test costs, reduced design iterations, and significant improved fault coverage. In this paper, we present a novel register allocation method, which is based on weighted graph coloring algorithm, targeting testability improvement for digital circuits. In our register allocation method, several high-level testability parameters including sequential depth, sequential loop, and controllability/observability are considered. Our experiments show using this register allocation method results in significant improvement in automatic test pattern generation time... 

One of the underlying factors in the conservation and development of urban green spaces is the available water resources use for green areas in each region. The primary purpose of this study is to introduce the integration of a proper simulation method for runoff along with AHP-PROMETHEE decision-making method for water resources management in urban basins. The application of this approach was investigated in the city Buin Zahra of Qazvin Province of Iran. In the first step by using the analytic hierarchy process (AHP), the available water resources in the case study were weighted. In the second step, the water resources of the municipal and residential wells and water collected by... 

Improving testability during the early stages of High-Level Synthesis (HLS) has several benefits, including reduced test hardware overhead, reduced test costs, reduced design iteration, and significant improved fault coverage. In this paper, we present a novel register allocation method, which is based on weighted graph coloring algorithm, targeting testability improvement for digital circuits. The topics covered in this paper include an overview of HLS and testability parameters, our testability model and experimental results  

Improving testability during the early stages of High-Level Synthesis (HLS) reduces test hardware overheads, test costs, design iterations, and also improves fault coverage. In this paper, we present a novel register allocation algorithm which is based on weighted graph coloring, targeting testability improvement. © 2003 IEEE  

We consider a class of optimization problems called movement minimization on euclidean plane. Given a set of m nodes on the plane, the aim is to achieve some specific property by minimum movement of the nodes. We consider two specific properties, namely the connectivity (Con) and realization of a given topology (Topol). By minimum movement, we mean either the sum of all movements (Sum) or the maximum movement (Max). We obtain several approximation algorithms and some hardness results for these four problems. We obtain an O(m) -factor approximation for ConMax and ConSum and extend some known result on graphical grounds and obtain inapproximability results on the geometrical grounds. For the... 

Assume that we are given a set of points some of which are black and the rest are white. The goal is to find a set of convex polygons with maximum total area that cover all white points and exclude all black points. We study the problem on three different settings (based on overlapping between different convex polygons): (1) In case convex polygons are permitted to have common area, we present a polynomial algorithm. (2) In case convex polygons are not allowed to have common area but are allowed to have common vertices, we prove the NP-hardness of the problem and propose an algorithm whose output is at least (OPTlog(2n/OPT)+2log(n))1/4. (3) Finally, in case convex polygons are not allowed to... 

In this paper, for the first time, chaotic behavior of a classical moving-mirror Fabry-Perot cavity is obtained by finding numerical solution of a system of delay differential equations (previously obtained by a phenomenological approach (T. Carmon, M. C. Cross, K. J. Vahala, Phys. Rev. Lett. 98 (2007) 167203)). Fourier transform of the electromagnetic power for different values of pump power is calculated. By increasing the power, a period-doubling route to chaos is observed. Since the quality factor of the cavity has an important role in the chaotic behavior, variation of Lyapunov exponent and threshold power for the onset of chaos versus quality factor are investigated. A near linear... 

There has been no isolated word recognition database for the Persian language so far. In this paper we introduce FarsName dataset which contains 20 thousands isolated-word Persian utterances spoken by 226 speakers from all regions of the country each saying an average of 88 Persian names. There is a total of 5235 unique names in this dataset. Various cell phone brands have been used to record this dataset. This indicates the high diversity of the utterances in this dataset. We have been able to achieve 10.34% WER on this set using Kaldi. This is a very good performance considering the recording environment have been normal and potentially noisy. © 2017 IEEE  

We introduce hyper-D-width and hyper-T-width as the first stable (see Definition 3) measures of connectivity for hypergraphs. After studying some of their properties and, in particular, proposing an algorithm for computing nearly optimal hyper-T-decomposition when hyper-T-width is constant, we introduce some applications of hyper-D-width and hyper-T-width in solving hard problems such as minimum vertex cover, minimum dominating set, and multicut  

Precipitation of strontium sulfate (or SrSO4) has already been distinguished as one of the most costly and critical problems which may occur in process industries and oilfield operations. Costs due to scaling and remedial actions that need to be taken afterward are generally high owing to low solubility of SrSO4 in aqueous solutions. Therefore, a thorough understanding of the SrSO4 thermodynamic behavior under various operating conditions is vital to predict or even avoid the overall damage caused by scaling. The primary aim of this work is to develop a model based on Least Squares Support Vector Machine (LSSVM) and Coupled Simulated Annealing (CSA) referred to as CSA-LSSVM to predict... 

We consider a market in which two competing sellers offer two similar products on a social network. In this market, each agent chooses iteratively between the products based on her neighbors reactions and prices. This introduces two games: one between the agents and one between the sellers. We show that the first game is a full potential game and provide an algorithm to compute its convergence point. We also study various properties of the second game such as its equilibrium points and convergence  

A green, effortless, and protective one-pot three-component process for the synthesis of derivatives using cycloadition catching azomethineylides in situ created by means of decarboxylative build-up of sarcosine and isatin has been developed in hexyltriphenylphosphonium bromide (HTPB) as an ionic liquid and recyclable solvent in supreme yield without the use of a catalyst under ultrasonic irradiation. This method offers mild reaction conditions, excellent products yields in shorter reaction times, ease of operation and environmentally friendly process and high ragio and stereoselectivity. The anticancer activity of all new compounds has been investigated against four cell lines. Also, the... 

The Three-Dimensional Network on Chip (3D NoC) is an interconnection architecture designed to address the increasing communication demands between processing cores. However, as traffic and power density continues to rise, efficient traffic management and thermal regulation within these chips have become crucial issues. One common problem encountered in mesh-based NoC structures, regardless of the routing approach employed, is traffic congestion in the central region. This paper introduces a novel routing algorithm named an Oblivious Congested Region Avoiding Routing Algorithm (OCRA) to evenly distribute packet flow across the entire network. OCRA addresses the traffic imbalance by statically... 

Deposition of barium sulfate (or BaSO4) has already been recognized as a devastating problem facing process industries and oilfield operations, mainly owing to its low solubility in aqueous solutions. Predicting and also preventing the overall damage caused by BaSO4 precipitation requires a profound knowledge of its solubility under different thermodynamic conditions. The main aim of this study is to develop a solubility prediction model based on a hybrid of least squares support vector nachines (LSSVM) and coupled simulated annealing (CSA) aiming to predict the solubility of barium sulfate over wide ranges of temperature, pressure and ionic compositions. Results indicate that predictions of... 

The degradation of methyl tert-butyl ether (MTBE) was investigated in the aqueous solution of coated ZnO onto magnetite nanoparticale based on an advanced photocatalytic oxidation process. The photocatalysts were synthesized by coating of ZnO onto magnetite using precipitation method. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibration sample magnetometer (VSM). Besides, specific surface area was also determined by BET method. The four effective factors including pH of the reaction mixture, Fe3O4/ZnO magnetic nanoparticles concentration, initial MTBE concentration and molar ratio of [H2O2]/ [MTBE] were optimized using response surface... 

The interaction of dislocation with strengthening particles, including primary and secondary γ′, during different stages of creep of Rene-80 was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). During creep of the alloy at 871 °C under stress of 290 MPa, the dislocation network was formed during the early stages of creep, and the dislocation glide and climb process were the predominant mechanism of deformation. The density of dislocation network became more populated during the later stages of the creep, and at the latest stage of the creep, primary particles shearing were observed alongside with the dislocation glide and climb. Shearing of γ′...