Sharif Digital Repository

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... 

Introductions: The routing Problem in SMS networks, start from subscriber called origin and end to other subscriber called destination. SMSs passed throw the switches, relay and routers. When the traffic of a SMS network increase, a global optimization is required to reduce the charge that SMS center must be paid meanwhile maximize total flow and minimize delivery time.
Methods: in this study after investigation in Short Message service, Routing Algorithms and letreture review, first we used our models for Telephone networks. The total model with Features and constrains was build. In order apply this model on Mobile networks, with using Latin Multy Plications Algorithms we develope a... 

Cost Estimation plays an essential and role in UAV (Unmanned Aerial Vehicles) Projects. By increasing the complexity of new unmanned systems, the importance of this task augments. Additionally, up to now, a comprehensive approach has not been adopted internationally. But in parallel a number of international companies and organizations has developed specific methods by themselves; confined to their corporate.
This project pursues developing a complexity-based model for cost estimation of unmanned aerial vehicles, especially Jet UAVs. However, it’s anticipated that this model may be utilized for all kind of systems, but it seems that jet UAVs use it with a better and more reliable... 

In this paper, we studied a two-echelon inventory system which consists of one central warehouse and one retailer. All installations follow base stock inventory management policy. The customers arrive at retailer according to Poisson distribution. The demand is satisfied when both central warehouse and retailer have positive on-hand inventory. Otherwise, the demand is lost. The lead time of central warehouse and the time needed to replenish orders of retailer are assumed to be exponentially distributed. The purpose of this study is to minimize the expected long-run total cost of the system per unit time. Total cost of the system includes holding costs of central warehouse and retailer, cost... 

Industrial programs are known as engine of development plans in Iran. These types of programs also known as mega projects that have multi dimension nature of the project. In fulfillment of doing mega project, consideration on many dimensions as several engineering process, complex project management issues, social responsibilities, cultural issues, and many other affecting dimensions should be done.As a point of view in successful project, the management (HAROLD KERZNER, 2006) requires finishing projects at cost, time, and quality and so on, but success of the industrial programs and mega projects also have effects on countries economy and improvements.For a country development, it is needed... 

Double angle connections, which are welded to the beam web and bolted to the column flange, are usually used to make hinged or semi-hinged connections. Several models are presented in this study whose geometrical properties are different. The finite element software package is used to develop the finite element analysis of the connections. An analytical method is presented that can be used to determine the behavior and deformation for this type of connection. The correctness of Moment-rotation curves of finite element analysis for each connection has been ascertained by comparison, using analytical technique; and a very good agreement has been obtained  

In this thesis, various methods for solving the classification problem with algorithms for some of their estimations, will be discussed. First, linear discriminant analysis (LDA), which is the most basic likelihood based method of classification is studied. In the next section, regularized discriminant analysis, a version of LDA in which the covariance matrix of each class is shrank toward the identity matrix, is studied. Then the ridge fusion in which a penalty is added to the likelihood function so that in the joint estimation of covariance matrices of dierent classes, all arrays become equal as much as possible is discussed. In the joint graphical lasso,precision matrices of dierent... 

Business process management (BPM) is an approach which helps managers to gain success in their organization by becoming capable of identifying and developing their processes. Process improvement is a difficult and important step in BPM since modern organizations have a huge number of processes and activities with complex and complicated relationships and interrelationships. In this work our goal is to rank and prioritize processes based on operational limitations of the organization such as budget, human resources, consumer resources and also relationships among processes have been considered and finally develop a portfolio of processes which are vital and essential for improvement.... 

The worldwide increase in greenhouse gases is one of the most important human concerns today, and reducing emissions is on the agenda of politicians and the international community. Globally, the transportation fleet is one of the major sources of environmental pollutants due to the use of fossil fuels, and replacing this fleet with electric vehicles will play an important role in reducing the emission of environmental pollutants. These environmental concerns and the advancement of technologies used in electric vehicles in recent years have led to a relative increase in the presence of electric vehicles in the transportation network. The acceptance of these cars, on the one hand,... 

In the current century, an energy storage is one of the critical and important factors affecting on human life. Rechargeable batteries, specially Lithium ion batteries (LIBs), can be considered as ideal energy storage devices including various advantages e.g. high energy and power densities. In this work, Tin IV sulfide (SnS2) and its composites, making by conductive materials e.g. Reduced Graphene Oxide (SnS2@rGO), are prepared during two different synthesis methods consisting of Hydrothermal and Hot-bath, and their properties are investigated as anode material in LIB. The structural and electrochemical analyses demonstrated that the composite sample prepared by hot-bath method exhibited...