Sharif Digital Repository

According to key importance of bridges in transportation system vital routes, a need to study and survey of bridges against destructive factors exist. Among these, bridges with concrete deck are widely used. One of the most important factors in destruction of these bridges is steel reinforcements corrosion and destruction of bridge deck. So in order to reduce the aggregation of reinforcements in critical sections and performance improvement of deck beams, a reinforcing substance which is not only resistant against corrosion but benefits from high resistance and stiffness is implemented.In this research the case studied bridge is simulated by finite elements software in two cases; reinforced... 

The experience from the performance of buildings during past earthquakes has shown that asymmetric buildings often sustain more extensive damages as compared to the symmetric buildings. The rules of seismic design codes about these buildings are based on investigation of single story buildings in the elastic range and they use rigidity eccentricity as main irregularity criterion. Inasmuch as during damaging earthquakes some lateral force resisting elements will not remain elastic and they reach yield, rigidity eccentricity will no longer be an appropriate parameter to represent the asymmetry of structure; thereby, in these building all centers of mass, rigidity, and strength should be paid... 

Memories are one of the main component in the embedded systems, and owing to their vulnerability to error, this part of system must be fault tolerant. Single error correction (SEC) codes are one of the most commonly used methods against sot errors. However, on the other hands as the technology scales, multiple bit upsets (MBUs) are becoming more likely to occur in the memories and the SEC codes have lost their effectiveness in fault coverage. Therefore a greater attention is devoted to the codes with the higher fault coverage such as single error correction/double error detection (SEC/DED) codes. These codes increase the delay, area and power consumption overhead. These parameters are the... 

In this research Feature Recognition technique for the 2.5D parts in Boundr Representation ( B-Rep ) solid modeling was used.
This method uses DXF file and convert the wire model to B-rep model to recognize the Face, Inner loop and Outer loop. The algorithm of recognition the Face, Inner loop,.. were prepared and a software (visual basic) was developed.In a case study a part with a protrusion, depression and a hole was recognized and then the effect of this method in comparison to the traditional methods on productivity was surveyed  

Separating colored points is one of the important problems in computational geometry. In separating colored points problems a set of colored points in Euclidean space are given that each color designates a set of certain data.Different problems can be defined in the colored points subject. Among them,separating colored points is studied in this thesis. It is supposed that two sets of blue and red points are given. It is desired to find the minimum number of rectangles that separate the blue points from the red points. It is demonstrated hat if P ̸= NP then there is no polynomial time algorithm for solving this problem. Then, a constant factor approximation algorithm is introduced and applied... 

Even though a considerable amount of research has been conducted on composite wall system during past years, very limited research has been reported on shear walls strengthened by steel plates. In 2008, the composite shear wall, which consisted of reinforced concrete wall, retrofitted by steel plates, attached to both sides of RC walls using mechanical connectors in form of shear studs, bolts or lateral ties tested under axial load and lateral force. In this research, seismic behavior of RC shear walls strengthened by diagonal strips of steel plates is going to be studied. The result will be compared with RC shear wall which fully covered by steel plates.The behavior of RC shear wall will be... 

Recently concrete filled steel tubular columns developed in the construction industry. In these types of columns, concrete and steel have efficient and complementary performance because of proper confinement provided by steel tube for concrete which leads to increase strength and ductility of concrete, also concrete prevents local and inward buckling of steel tube. CFST columns have several advantages over conventional reinforced concrete columns such as elimination of formwork and reinforcement, rapid construction, decrease in the column dimensions and saving extra floor space and also improvement in the load-carrying capacity, ductility and energy absorption ability. Despite the above... 

After positivists, that argue the structure and growth of scientific knowledge is rational, and constructivists, that argue science is based on irrational basis, analysis of structure and growth of scientific knowledge, in few decades ago, has developed from cognitive perspective. In this approach, i.e cognitive phase of philosophy of science, the role of concepts, that organized around hierarchies, become important. In current dissertation, we have considered views of paul Thagard, the cognitive scientist, about conceptual systems, and structure of science from cognitive approach. Thagard, postulating the truth of scientific developments, describes mental representations and processes in... 

3D-object modeling and its representation in computers are one of the interested fields in computer science and engineering and problems like object and environment modeling, representation, storage and physical interactions are some of the important problems in this field. Increasing the applications of the technologies like localization, machine vision and virtual reality made the 3D-object modeling and its related problems, like 3D-model extraction and reconstruction, a nowadays interested challenges and a variety of solutions such as time of flight sensors,
structured light, sonar sensors and multi-camera reconstruction are presented for it. Multi-camera solutions, just like the... 

Given a graph G with a set of terminals, two weight functions c and d defined on the edge set of G, and a bound D, a popular NP-hard problem in designing networks is to find the minimum cost Steiner tree (under function c) in G, to connect all terminals in such a way that its diameter (under function d) is bounded by D. Marathe et al. [1] proposed an (O(log2n);O(log2n)) approximation algorithm for this bicriteria problem, where n is the number of terminals. The first factor reflects the approximation ratio on the diameter bound D, and the second factor indicates the cost-approximation ratio. Later, Kapoor and Sarwat [2] introduced a parameterized approximation algorithm with performance... 

The subject of this thesis is a two-echelon inventory system with a manufacturer and multiple distribution centers (DCs) that satisfy the demand originating from multiple sources. Demand from each source follows an independent Poisson process. The transportation times between the manufacturer and the DCs are assumed to be positive which may require keeping inventory at both the warehouse and the DCs. Inventory in both echelons is managed using the base-stock policy. The manufacturer works with
M/M/c product system. The cost of demand fulfillment for each DC consists of inventory holding and backlog costs. The objective is to determine the optimal base-stock levels at the DC  

The present paper discusses the possibility of adding recycled polymer fibres to high performance concrete (HPC). Fibres used in this study were recovered from discarded car timing belts. To investigate different characteristics of the concrete specimens several destructive and non-destructive tests, such as compressive strength, modulus of rupture, flexural toughness, ultrasonic velocity and electrical resistance tests were carried out. In addition, slump flow tests were conducted on the fresh concrete. Experimental results from the study showed that the use of low percentages (up to 0.5%) of waste fibres improved the modulus of rupture and flexural toughness. Based on ultrasonic and... 

In today’s competitive world, using an efficient forecast method is necessity for companies. To now, many forecast methods have been developed, but many of them have not an expected efficiency. In this research, we develop a new hybrid forecast method with application of forecasting retails demand. The hybrid method is the combination of ARIMA method and neural networks. To test the efficiency of the method we use the 96 weeks data of plastic containers demand. We also comprise the hybrid method with other forecast methods including naïve method, ARIMA method and neural network method by applying root mean square error and mean absolute percentage error indexes. In the case of plastic... 

Tunnel form structures have been proposed in building industry during 40 years for financial saving, suitable structural performance and seismic behavior, and the possibility of performance in an industrial form; and they have also been brought up as one of the innovative technologies of construction in Iran for a couple of years. So far, these structures have been subject to study by the researchers less than frame structures. In comparison to the common structures, evaluating the behavior of these structures is analyzable as two or three-dimensional elements. In this research, the nonlinear behavior of these structures has been simulated and evaluated by using three-dimensional elements;... 

In this research, effect process TOC in MRP system have been studied,therefore, first the hypothesis in TOC process and MRP system have been studied and generated. Afterward, whit the use of library and sydies the research guestions have been compiled. The society under studyis an aluminium oasts manufacturing daycust tabriz company. For surveying the memtioned company, samed documents hase been studied. After gathering all information and documents, and analyzing them, the result has been revealed. Therefore the effect of TOC and MRP process an production system has been comeout. At present situation, the mast crucial factors for suruival and compdtetion are ones couse the reduction of the... 

Price and warranty are two powerful marketing tool that can stimulate consumers’ purchase willingness. Therefore, producers must choose the appropriate price and warranty that can stimulate customers to purchase the quantity that will achieve the maximum profit. This study investigates optimal strategies for price and warranty length of a new product to maximize profit of a producer during lifecycle of the product. We consider both durable products and non-durable ones. Customers buy non-durable products many times but if we consider the planning horizon relatively short, each customer buys one product during the period. So, the market for non-durable products is static and for durable ones... 

When demand for a product is price sensitive, pricing and lot sizing decisions are interdependent. Similarly, when a product is highly perishable, the demand may need to be backlogged to avoid costs due to deterioration, i.e., perishability and backlogging are complementary conditions.In this thesis we stablish two economic production quantity models for deteriorating items under conditions of finite production, exponential decay and partial backordering and lost sale. Two joint pricing inventory control models are developed for the problem by employing different modeling approaches over an infinite planning horizon. In two models, customer is viewed to be impatient and the fraction of the... 

Pattern recognition in data streams using bounded memory and bounded time is a difficult task. There are many techniques for recognizing patterns but when we talk about data streams these algorithms became useless since there are no enough memory to store all data. In data stream model the entire data is not available at any time and we don’t have enough time processing each data.
In this thesis we consider current methods for recognizing patterns from a data streams. The goal pattern in this study was the minimum total area of k convex polygons encloses all data  

This set is an introduction to a method for studying Constant Mean Curvature Surfaces (CMC) and Minimal Surfaces with harmonic maps . In recent years , integrable systems approaches for the construction of CMC surfaces in R3 have been developed . One of them , using finite type solutions of the sinh-Gordon equation .Another approach to CMC surfaces was developed by J. Dorfmeister, F. Pedit, and H. Wu in 2006 . It is commonly called the DPW method. The Gauss map of a CMC surface is a harmonic map , and in the DPW method every such harmonic map can be obtained from some holomorphic potential in a loop algebra . This method gives a description of all immersed CMC surfaces in R3 . in this paper... 

In recent years, more attention has been paid to the development of lightweight concrete (LWC). Study of such this material had been marked due to more importance of use of it.It is now well known that in order to model cracks the finite element model is more suitable.The fracture of quasi-brittle material such as concreteincludesthe fracture process zone (FPZ).Cohesive zone model is considered the most common model used for FPZ modeling.Therefore, in this article the propagation of cohesive cracks inLWC is modeled using the extended finite element method (XFEM). In this study, modeling showed fastgrowth and propagation of cracks inLWC. Due to its cavities and pores, LWC shows to be more...