Sharif Digital Repository

The Swaⅿpⅼanⅾ prograⅿ was ⅾeveⅼopeⅾ to ⅽonstrain the effeⅽtive fieⅼⅾ theories that ⅽan be ⅽoⅿpatibⅼe with quantuⅿ gravity. Our ⅾissertation foⅽuses on one of the ⅽonjeⅽtures of this prograⅿ، whiⅽh is known as the Ⅾark Ⅾiⅿension، that preⅾiⅽts the existenⅽe of a ⅿesosⅽopiⅽ fifth ⅾiⅿension of the orⅾer of (mev)−1 . Before exaⅿining the ⅾark ⅾi− ⅿension، however، we introⅾuⅽe soⅿe reⅼateⅾ ⅽonjeⅽtures. Our priⅿary goaⅼ is to stuⅾy the ⅾynaⅿiⅽs of the ⅾark ⅾiⅿension through ⅽosⅿoⅼogiⅽaⅼ observations. To this enⅾ، we begin by proviⅾing a brief overview of 5−ⅾiⅿensionaⅼ fieⅼⅾ theory anⅾ the resuⅼting speⅽ− truⅿ after ⅽoⅿpaⅽtifiⅽation. Next، we ⅾerive the Frieⅾⅿan equations for spaⅽes with ⅿore than... 

Many embedded multicore systems can benefit from a memory hierarchy to bridge the processor/memory speed gap. Embedded systems usually utilize a cacheless architecture to avoid the unpredictable behavior. Unlike caches, scratchpad memories (SPM) are software controlled and hence the execution time of applications on such systems can be accurately predicted. Scheduling the tasks of an embedded multicore application and partitioning the available SPM budget among these cores are two critical issues in such systems. Often, these are considered separately, such a decoupled approach may miss better quality schedules. In this paper, we present an integrated approach to task scheduling and SPM... 

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... 

Local scouring at the downstream of sluice gates in the erosive beds is one of the main concerns of hydraulic engineers because of the significant damage that it can cause to the hydraulic structures. It is important to control the local scour depth at downstream of hydraulic structures to ensure safety operation of these systems. Many researchers have conducted various studies to predict the maximum depth and diameter of scour hole and develop new methods in order to control this phenomenon. One way to overcome this problem is the use of apron, or non-erosive bed. In order to shorten the apron length or decrease the effect of the... 

In this thesis, the satellite constellation orbit design for regional coverage is investigated. The orbits of satellites in a constellation for Earth observation missions play a crucial role in performance and characteristics of the mission; for example the image resolution, the area of coverage, and the coverage interval. In this thesis the problem is to find the optimal initial orbital elements for meeting the earth observation mission objectives for one or several sites. The cost functions are the total coverage time, the maximum gap time, time average gap, altitude, and number of satellites. The problem is solved in a multi-objective manner for different combination of two of the above... 

Nowadays marine-tourism industry, especially under water tourism, has become very attractive. Thus, numerous under water vehicles are designed and constructed. The primary objective of the present study is to design an underwater vehicle capable of carrying ten passengers. Tow system is proposed as propulsion system. Due to the high costs, noise and vibrations of existing propulsion systems in medium size vehicles which contradicts the goal of calm atmosphere for passenger, the proposing system seems suitable and pragmatic. Two-part tow system is utilized to enhance the stability of the under water vehicle named Towfish. In this study the structure of towfish is being designed. Then,... 

This paper provides and empirical investigation of individual labor supply of Iranian spouses in a collective framework in which gender ratio and plays a central role in the decision process in household. The data set is taken from the socioeconomic characteristics of panel survey over 2001-2004 and ten yearly headcount of Iran. We have conducted the parameters estimation and hypothesis testing by Semykina, A. and Wooldridge, J.M., (2005) generalized procedure of sample selection in panel data model. Our findings explore that females’ labor supply is affected significantly and strongly by the gender ratio, (total number of males over the females in provinces, both in urban and rural areas).... 

Design of anonymous authentication scheme is one of the most important challenges in Vehicular Ad hoc Networks (VANET). Most of the existing schemes have high computational and communication overhead and they do not meet security requirements. Recently, Azees et al. have introduced an Efficient Anonymous Authentication with Conditional Privacy-Preserving (EAAP) scheme for VANET and claimed that it is secure. We show that this protocol is vulnerable against replay attack, impersonation attack and message modification attack. Also, we show that the messages sent by a vehicle are linkable. Therefore, an adversary can easily track the vehicles. In addition, it is shown that vehicles face with... 

In this thesis, the physics related to liquid jet injection from injectors with three different crescent-shaped cross-sectional levels into steady and transverse flow were studied. The imaging method in this research was based on shadowgraph, which enables high-speed imaging. With the help of the obtained images, the breakup regimes, including Rayleigh, first and second wind-induced instabilities, were observed for injection into the steady flow. Furthermore, breakup regimes for jet injection into transverse flow, including columnar, columnar-bag, and bag, were also observed. The characteristics of the breakup height in steady flow and the length and height of the breakup along with the jet... 

One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s... 

Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and... 

Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework... 

This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve... 

Poincare conjecture is one of the rst eorts for classifying 3-manifolds that was stated in the begining of 20th century. Eorts for proving this conjecture continued for about 100 years and nally Perelman has solved it in 2003. He has used Ricci ow which has been invented by Richard Hamilton in the early 80's. In this thesis rst we will introduce Ricci ow and will state the results before Perelman such as short time and long time existence of solution. Then we will mention some applications of Ricci ow and will state an explanation of the proof of uniformization and Calabi conjecture by Ricci ow. After that we start the main part of the thesis. In this part we will montion one of the...