Sharif Digital Repository

Catalytic cracking of iso and normal butane over HZSM-5 at several temperatures and a variety of contact time and different partial pressures of hydrocarbon feed was conducted. Experiments indicate that the operating conditions have considerable effects on final product distribution and feed conversion. Results show that high temperatures, low contact time and partial pressure of paraffin feed favor the light olefin production, particularly propylene production. Results obtained for iso-butane show a similar conversion values in comparison to n-butane but a higher olefin and propylene selectivity. Finally kinetic modeling of both iso and normal butane cracking was performed based on a lump... 

Nowadays, we observe the growth in the number of mobile smart phones. These smart phones have had an impressive progress in software and hardware. Many studies have focused on utilizing this new platform. One of these areas of research is collecting information from environment.Two major challenges for a successful crowdsourcing system are engaging a sufficient number of workers and validating of their registered data, which make the system more reliable. Collecting data from different points of a territory can be defined as some tasks and should be assigned to users near those tasks properly. Some users want a monetary reward for the cost they incur. On the other hand, information... 

Many of Iran's wetlands are going dry because of the expansion of anthropogenic activities like the exorbitant withdrawal of groundwater resources and excessive use of water for agricultural purposes. Bakhtegan, Hoor-ol-azim, Anzali, and Miankaleh are some of the most notable examples of this issue in the past two decades. The crucial role of wetlands in preserving the biodiversity of flora and fauna and supplying groundwater resources necessitates continuous monitoring of the quantitative and qualitative changes in the surface water of wetlands. The main focus of this research is quantifying the reduction in wetlands' surface water using K-means and random forest algorithms based on... 

Due to the increasing development of digital systems based on limited energy sources (i.e. battery), energy efficiency has become one of the most important concerns in the design of these systems. The use of multi-core architecture is an effective solution for the problem of reducing energy consumption. Hence using it in digital systems has become more common. In addition, enabling methods for reducing energy consumption on processor, helps in making energy more efficient. DVFS and DPM are the two major methods used for reducing dynamic and static energy consumption of processors. The using of multi-core architecture due to the higher chip density, results the static and dynamic energy... 

Recently in civil engineering prestressed concrete slab applications is increasing, and typically results in overall economy and provides satisfactory structural performance. In The present work, two-way prestressed concrete slabs have been considered and during designing process with the ACI-2005 code and due to economic plan, prestressed slabs were studied in transfer, service and final conditions. ACI code insists that two-way prestressed slabs shall be classified as class U (without cracking) that means section must be untracked in all conditions (code reference 18.3.3). In addition, two-way prestressed slabs must be prestressed in both directions for 100% of load, and this means that... 

In this paper, the response of a concrete one-story frame with smart rebars under static lateral loading has been numerically studied, using Finite Element Method. The material used in this study is Shape Memory Alloy (SMA) which contains nickel and titanium elements. During lateral loading, rebars yield or concrete crushes in compression zone in some parts of the RC frames and also residual deflections are created in the structure. The SMA exhibits little residual strains under cycles of loading and unloading even after passing the yielding zone. In addition, SMAs have a good energy dissipation capacity that helps reduce damage while increasing structural capacity. In this study, SMA rebars... 

Present work focuses on the influence of Heteroatom(s) on the bacisity of specific group of amines through the intramolecular hydrogen bonding. This group includes Aza-Crown Ethers specifically. We used Spartan and Gaussian packages to gain optimized structures for all compounds in order to explore the influence of the intramolecular hydrogen bonding on the bacisity of amines. All the gas phase optimizations and energy calculations were performed at the DFT/B3LYP/6-311++G(d,p) level of theory. The Hf/6-31+G(d,p) level was used for all single point calculations in the solution phase. As commonly used solvents in organic and biological reactions, the solution phase calculations were carried... 

Today, Progressive Collapse analysis of Structures has a great rule in predict and preventing of overall collapse of structures due to local damage to few elements. After World Trade Center collapse, Progressive collapse analysis became more important. According to better ductility of Concrete Filled Steel Tubular Columns, because of existence of core concrete confinement, it is prospected that using this type of columns will lead to better resistance against progressive collapse. In this study, structures with concrete filled steel tubular columns will be examined in progressive collapse. In addition, in this study, a numerical model was proposed to model concrete filled steel tubular... 

Cache memory is one of the most important parts of the microprocessors. Caches improve performance by bringing data and instructions near the processors and decreasing the access time to data and instructions. But caches are also vulnerable to some kind of error called soft error. When an error happens in a cache, suddenly can propagate throughout the system and affect the integrity and reliability of the overall system. There are actually two types of errors in cache memories, permanent (hard) errors and transient (soft) errors. Previous studies have shown that about 92% of system reboots are initiated by soft-error occurring in cache memory. Soft-errors have two main sources, alpha... 

In this project, the photoelectrochemical properties of ZnO nanostructures modified by CdS and Graphene was studied. Firs, titanium foil was cut into rectangular shape with 1cm width and 3 cm length, cleaned by rinsing in acetone and ethanol and annealed at 4000C for an hour. As a result, a thin layer of titanium oxide was formed on Ti sheet. Then a layer of grapheme oxide was deposited on substrate using Electrophoretic deposition (EPD). After that, ZnO nanostructure was deposited on the TiO2 substrate using Electropulsation (EP) with 20 consecutive pulse followed by 3 minutes Electrodeposition (ED). Using SEM analysis, the morphology of ZnO was determined to be nanopetals in which the... 

These days usage of prestressed structures in civil projects are increased significantly. One of these structures is prestressed concrete beam. Considering of such charactristics as failure loads , maximum loads, ductility and occurence and extension of cracks in prestressed concrete beams are interested by civil engineering so in this project we try to investigate the effect of increasing in nonprestressed bars with different arrangements in six specimens.
The load enters in static way on each specimen and supports are simple. Considering the results of experiments, ductility increases significantly because of adding longitude and transverse bars and brittle behavior of speciments... 

Compile-time optimizations play an important role in the efficient design of real-time embedded systems. Usually, compile-time optimizations are designed to reduce average-case execution time (ACET). While ACET is a main concern in high-performance computing systems, in realtime embedded systems concerns are different and worst-case execution time (WCET) is much more important than ACET. Therefore, WCET reduction is more desirable than ACET reduction in many real-time embedded systems. In this thesis, we propose a compile-time optimization method aimed at reducing WCET in real-time embedded systems. In the proposed method, based on the predicated execution capability of embedded processors,... 

The aim of this study was to evaluate the effects of applying low replacement ratios (0.75% and 1.50% of the binder weight) of nano-SiO2 particles with different specific surface areas (200 and 380 m2/g) on the properties of high-performance concrete (HPC). Mechanical (compressive and splitting tensile strengths), electrical resistivity, non-destructive (ultrasonic pulse velocity), and microstructural (mercury intrusion porosimetry, X-ray diffraction, and scanning electron microscopy) tests were conducted to investigate the macroscopic and microscopic effects of nano-SiO2 particles on HPC characteristics. The results indicated that the performance of nano-SiO2 particles significantly... 

Lateral confinement is a proven method of increasing strength, stiffness and ductility of concrete columns. This is attributed to a created tri-axial stress state in the concrete core due to the confinement resulting in a higher level of endurable deviatoric stress. Plastic pipes are able to create such a confining medium in concrete-filled UPVC tube (CFUT) columns and therefore they can provide the concrete with some benefits of concrete filled steel tube (CFST) column system. Besides, these pipes are cheap, light and they are also easy to handle. Furthermore, they are resistant to corrosion or other forms of deterioration and recyclable and in this aspect, they are... 

One of the crucial matters in the area of Supply Chain Management is the ability of a supply chain to act and react under different circumstances. A helpful tool to understand the supply chain is simulation modeling. With the help of simulation modeling, we can provide the opportunity for the agents in a model to perform based on the defined environment.In the current research, a complete literature review is performed on the topics of supply chain planning and various distribution models and algorithms. With the focus on the vaccine as a critical item, we propose a model to distribute vaccines based on the degree of agents, and we realize that vaccine distribution, while facing huge demand... 

This study presents an experimental and numerical investigation on the compressive behavior of a new type of composite column which consists of both solid and hollow concrete-filled UPVC tube with and without GFRP wraps.Composite construction has been often more economical than traditional concrete construction, because this system realizes the most effective use of concrete, and composite members in the structural system.The enormous potential of using plastic tubes in composite systems will be illustrated by this research. It is an economical type of column in construction.This research aims to study the behavior of UPVC-confined columns under axial compression. A sum of 132 specimens are... 

Vehicles are safety-critical Cyber-Physical Systems (CPSs) consisting of hundreds of control units. The Engine Control Unit (ECU) is a fundamental part of a vehicle, and by applying reliability improvement techniques to the ECU, we can prevent catastrophes, performance degradation, and environmental damage. However, like any other CPS, traditional reliability assessment of the cyber and physical parts is insufficient as these parts are tightly coupled. Furthermore, the ECU consists of many mutually dependent subsystems, the failure of which will fail the whole vehicle system. Hence, to compensate for the hardware redundancy cost, we have improved the reliability of the system's bottleneck.... 

Recently, many studies show that Augmented Reality (AR) and Automatic Speech Recognition (ASR) can help people with disabilities. In this thesis we examine the ability of combining AR and ASR technologies to implement a new system for helping deaf people. This system can instantly take a narrator's speech and convert it into a readable text and show it directly on AR display. Also, with this system, people do not need to learn sign-language to communicate with deaf people. To improve the accuracy of the system, we use Audio-Visual Speech Recognition (AVSR) as a backup for the ASR engine in noisy environments. AVSR is one of the advances in ASR technology that combines audio, video and facial... 

This thesis is related to applying survey of scientific inventory control methods in Khoramshahr Oil Extraction Company (KHOEC). KHOEC is the producer of edible oils in I.R of Iran and is a subset of E.T.K.A holding organization. The inventory costs of high consuming items are studied and optimized based on the optimal ordering policy (r, Q). First, the company raw materials are identified and classified based on ABC analysis method. For developing the new method of inventory control, the demand for each item is predicted, and the probability distribution of demand during the lead time is determined. Then according to this information and the desired service level of management, order point... 

Coupling of optical and mechanical degrees of freedom through radiation pressure was, first, observed in the experiments for detection of gravitational waves. Recent experimental advances have granted reality to the long-hankered-after coupling between microscopic and macroscopic systems. In the first step, this thesis will review different aspects of cavity Optomechanics, such as: cooling, side-band formation and dynamics of an Optomechanical cavity. Then we will go further and study the Optomechanical dynamics of a cavity in the presence of an atom. To do so, we will analyze the entanglement, created between the center of mass motion of the atom and the mirror and will probe into its...