Sharif Digital Repository

In this paper, we study the role of inlet gas temperature and jet to bed cross-section ratio on hydrodynamics and circulation patterns of particles in a spout-fluid bed. The system is modeled using CFD-TFM approach based on Eulerian-Eulerian method. Simulation results are validated by experimental data measured by (Link 2008. "PEPT and Discrete Particle Simulation Study of Spout-fluid Bed Regimes." Aiche Journal 54 (5): 1189-202). First, the sensitivity analysis of simulation results versus the most significant parameters are conducted to find the optimum values for each parameter. Subsequently, the role of inlet gas temperature and cross-section ratios are studied in detail. The simulation... 

Chemical processing of two-dimensional (2D) transition metal dichalcogenides has attracted immense attention due to their unique optical, electrical, and catalytic properties. In this paper, we show that under special conditions during seedless chemical vapor deposition (CVD), it is possible to grow large-area 2D WS2 layers with disc-shaped morphology, which has been scarcely reported. Detailed characterizations of the CVD-grown layers by Raman spectroscopy, atomic force microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy have revealed that a gradient in the precursor concentration in the gas phase and strain energy in the deposited hexagonal clusters favor... 

A potential peculiarity of software systems is that a large number of soft-errors are inherently derated (masked) at the software level. The rate of error-deration may depend on the type of algorithms and data structures used in the software. This paper investigates the effects of the underlying algorithms of programs on the rate of error-deration. Eight different benchmark programs were used in the study; each of them was implemented by four different algorithms, i.e. divide-and-conquer, dynamic, backtracking and branch-and-bound. About 10,000 errors were injected into each program in order to quantify and analyze the error-derating capabilities of different algorithm-designing- techniques.... 

An effective procedure to incorporate kinematic interaction (KI) aspects in seismic analysis of soil-structures systems was presented. In this regard, first, the effect of KI on the structural response was investigated with special focus on the role of rocking component of foundation input motion (FIM). This was performed parametrically for a wide range of selected nondimensional parameters, which well define the introduced simplified soil-structure model. It was observed that ignoring the effect of rocking input motion may introduce errors, which can be on the unsafe side especially for slender structures with large embedment ratios. On the other hand, it was known that introducing the... 

Submarine pipelines as the principal structural components are prone to fail by circumferential buckling under the effect of hydrostatic external pressure. Basically, the buckling capacity of a thin-walled pipe is dependent on "radius to thickness" ratio. At least two modes of local and overall buckling are possible in any pipeline system, which could be developed in pipe wall. A method of strengthening of pipes is developed in this paper to stop the failure. A total of 21 stiffened models are generated and analyzed using the well-known finite element program ABAQUS. In this study, the buckling and post-buckling behaviour of stiffened pipes are investigated by carrying out linear and... 

Three-dimensional orbits in the vicinity of the collinear libration points of the Sun-Earth/Moon barycenter system are currently being considered for use with a number of missions planed for 2000 and beyond. Since such libration point trajectories are, in general, unstable, spacecraft moving on these paths must use some form of trajectory control to remain close to their nominal orbit. In this paper, circular restricted three body problem is reviewed and a numerical method to control spacecrafts on periodic halo orbits around L1 and L2 collinear points of the Sun-Earth/Moon barycenter system is investigated. The control approach is based on the optimal control theory and implements variation... 

Rapid and exponential development of textual data in recent years has yielded to the need for automatic text summarization models which aim to automatically condense a piece of text into a shorter version. Although various unsupervised and machine learning-based approaches have been introduced for text summarization during the last decades, the emergence of deep learning has made remarkable progress in this field. However, deep learning-based text summarization models are still in their early steps of development and their potential has yet to be fully explored. Accordingly, a novel abstractive summarization model is proposed in this paper which utilized the combination of convolutional... 

One of challenging problems in the domain of web services is the web service composition (i.e the task of composing web services to create new services, capable of fulfilling a need that no single service can satisfy). In real application, there will be a lot of relevant web services for a simple goal, so the search space for such a problem is huge. In this research statement, we show how by extracting some prior knowledge and using simple heuristics, search space and search time can be reduced significantly  

Acording to the prevalence of cancer in today's societies, it is too important to find new drugs for that treatment. Cationic antimicrobial peptides that are able to eliminate a wide range of bacteria, fungi, parasites, viruses and unicellular, are natural anti-cancer agents. In the present study, the effect of cationic peptides of bee venom Melittin (ML) and Lactoferrin (LF) of camel milk which was loaded on the Perfluorooctyl Bromide (PFOB) nanoparticles, were examined on MCF7 cells. Nanoparticles using oil in water emulsion was prepared by ultra-thoracic and ultrasonic. Then ML and LF were separately added to the nanoparticles then incorporation of them were confirmed by tryptophan... 

In this paper, different aspects of the behavior of 2×2 pile groups under liquefaction-induced lateral spreading in a 3-layer soil profile is investigated using large scale 1g shake table test. Different parameters of the response of soil and piles including time-histories of accelerations, pore water pressures, displacements and bending moments are presented and discussed in the paper. In addition, distribution of lateral forces due to lateral spreading on individual piles of the groups is investigated in detail. The results show that total lateral forces on the piles are influenced by the shadow effect as well as the superstructure mass attached to the pile cap. It was also found that... 

In the calculation of the optimum loading pattern for a nuclear reactor, several parameters, including the multiplication factor maximization, the raising of the desired safety threshold during the cycle length and the flattening of the radial power peaking factor should be taken into account. Our evaluation of numerous probable arrangements within the VVER-1000 reactor core (approx. 6 × 10 14 cases) indicated that a direct search of the optimum loading pattern is not feasible. Hence, in this study, the weighting factor method and some constraints on the arrangement of the fuel assemblies were applied so that the above cases were reduced to only 244 possible arrangements. Then, using a... 

Liquefaction-induced lateral spreading has imposed severe damages to many important structures supported on pile foundations during past earthquakes. As a result, evaluation of pile response to lateral spreading is an important step towards safe and resistant design of pile foundations against this destructive phenomenon. Current paper aims to study the response of a group of piles subjected to liquefaction-induced lateral spreading using a large scale 1-g shake table test. General test results including time-histories of accelerations, pore water pressures, displacements and bending moments are presented and discussed in this paper. In addition, distribution of lateral soil pressure on... 

In this paper, the concentrations of fission products and fuel isotopes as well as the changes of the thermo-neutronic parameters of the Bushehr's VVER-1000 reactor were studied during the initial startup and the first cycle. In order to perform the time-dependent cell calculations and obtain the concentration of fuel elements, the WIMSD5-B code was used. Besides, by utilizing the CITATION-LDI2 code, the effective multiplication factor and the thermal power distribution of the reactor were calculated. A computer program (WERL code) was designed in order to perform accurate calculation of the temperature distribution of the reactor core. For this purpose, the Ross-Stoute, Weisman, and... 

Based on this study, the effects of two filter materials of pamis and escoria and comparing them with the sand bed were considered and analyzed. Three similar beds were made with 8 days hydraulic detention time and one primary sedimentation tank with 2-h time. One bed was filled as a witnessed test with sand and sec and third beds were filled with pamis and escoria stone for the study. To water the reeds with the urban wastewater, one urban wastewater system was used with these features BOD = 250 mg L-1, TSS = 200 mg L-1, COD = 300 mg L-1 and pH = 7.2, TP = 6 mg L-1, TN = 21 mg L-1; the pilot was used during 1 year and it was used later also. The experiments were done by use of the standard... 

This paper presents a new model to short-term prediction of air pollution using a new structure is based on the intelligent neural networks. A new structure known as Time Delay Cerebellar Model Arithmetic Computer (TD-CMAC), an extension to the CMAC, it requires fewer memory sizes. The new model is demonstrated and validated with three primary air pollutants known as carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen dioxide (NO 2). The simulation results for the half an hour ahead-prediction of the air pollutant data set show that the suggested new model is suitable for our purpose  

The economic growth or asset of country basically depends on the amount of goods which can be produced by the combination of land, capital, manpower and natural resources. Therefore, changing natural resources into production is the new process of economical development, and technology is the brain of this type of transformational activities. This tool not only makes the changing operation possible but also, in the world economy makes the survival and growth foundation of business enterprises. The Development of today's technology has caused some change in the productivity and costs, and because of this, the global and national structure in the areas of production, business and employment... 

Thanks to a wide range of pore sizes by nano/macro composites of SiOC/Al2O3, such composites can serve as different layers of the structure of Packed Bed Reactor Membranes (PBRM). In the present study, the Polymer-Derived Ceramics method (PDC) has been used to synthesize nano/macro structures. Firstly, the effect of toluene as an extra carbon source on structure and microstructure of SiOC glass-ceramics was evaluated, such that, 4% (Vol) toluene was recognized as the proper amount to facilitate the synthesis of β-SiC at 1300 °C proved by XRD, Raman spectroscopy, and HR-TEM. Moreover, the presence of micro/meso-porosities was assessed by BET and TEM, indicating the capability of SiOC to serve... 

In this paper, dynamic programming alignment is replaced by a particle swarm optimization (PSO) procedure in time warping problem. The basic PSO is a very slow process to be applied to speech recognition application. In order to achieve a higher performance, by inspiring of PSO optimization methodology, we introduced a PSO Inspired Time warping Algorithm (PTW) that significantly increase the computational performance of time warping in alignments of long length massive data sets. As a main enhancement, a pruning strategy with an add-in controlling threshold is defined in PTW that causes a considerable reduction in recognition time, while maintaining the system accuracy comparing to DTW. ©... 

Emerging STT-MRAM memories are promising alternatives for SRAM memories to tackle their low density and high static power consumption, but impose high energy consumption for reliable read/write operations. However, absolute data integrity is not required for many approximate computing applications, allowing energy savings with minimal quality loss. This paper proposes QuARK, a hardware/software approach for trading reliability of STT-MRAM caches for energy savings in the on-chip memory hierarchy of multi- A nd many-core systems running approximate applications. In contrast to SRAM-based cache-way-level actuators, QuARK utilizes fine-grained cache-line-level actuation knobs with different... 

Background: One of the most widely used evaluation methods in miRNA experiments is qRT-PCR. However, selecting suitable internal controls (IC) is crucial for qRT-PCR experiments. Currently, there is no consensus on the ICs for miRNA qRT-PCR experiments in breast cancer. To this end, we tried to identify the most stable (the least expression alteration) and promising miRNAs in normal and tumor breast tissues by employing TCGA miRNA-Seq data and then experimentally validated them on fresh clinical samples. Methods: A multi-component scoring system was used which takes into account multiple expression stability criteria as well as correlation with clinical characteristics. Furthermore, we...