Sharif Digital Repository

The trip demand information in the form of the origin-destination (OD) matrix is of significant importance in the transportation studies. Obtaining such a matrix by conventional methods requires a considerable amount of time, cost, and human resources. Traffic count and cellphone network data are two relatively inexpensive data that can be used for estimation of OD matrices as well as correction of prior matrices. The trip demand estimation problem is a bi-level model, and the gradient algorithm is one way to solve it. This study, by generalizing the gradient algorithm, attempts to a better use of the available data. In this algorithm, a complementary algorithm is used to solve the traffic... 

In this study, investigated the simulation flow over a double-delta wing. The flow field was simulated by three dimension grid and RANS flow equation by K-ω-SST model. In order to investigate effect of AOA and leading edge flap simulated variable AOA and leading edge flap angle. The results shows created two vortex in inside and outside the wing. The vortex burst at high AOA and the Lift decrease after vortex bursting. The using leading edge flap effect on the vortex power and postpone vortex bursting and increasing wing lift coefficient in the high AOA. Also the leading edge flap effect on the pitch moment coefficient and change the pitch moment coefficient curve slope. The other effects of... 

In this research, we investigate shape fitting problems in high dimensional streams and we provide lower bounds for the problems of minimum enclosing spherical shell and minimum enclosing cylindrical shell in streaming model. We will prove that no streaming algorithm can approximate these problems with constant factor with storage sub-exponential in dimension. More precisely, we will prove that every streaming algorithm that can solve these problems with storage sub-exponential in dimension, does not have an approximation factor better than√28 d1/3, where d is dimension of the input points. This is the first lower bound that has been proved for these two problems in high dimensional streams  

Nowadays, continuum robots have found many applications in the field of medicine, especially in minimally invasive treatments, due to their relative advantages over rigid robots. These advantages include more degrees of freedom, the ability to manufacture on micro and nano scales, and so on. Following the widespread popularity of these robots in various surgeries, including brain, cardiovascular, pulmonary, etc., the importance of their precise steering and control within the human body has also been identified. One of the methods for achieving this precision is through the use of a magnetic field to actuate these robots. This approach not only ensures safety for the human body but also... 

Proton exchange membrane (PEM) fuel cell performance is directly related to the flow channel design on bipolar plates. Power gains can be found by varying the type, size, or arrangement of channels. It has been understood that the flow field design has deterministic role on mass transport and water management in a PEM Fuel cell. This study concentrates on improvements in the fuel cell performance through optimization of channel dimensions and configurations. A 3D, multi-component numerical model of flow distribution based on the Navier-Stokes equations using individual computer code is presented. The simulation results showed excellent agreement with the experimental results in previous... 

Due to the intensification of competition in real markets and the increase in customer needs, manufacturers are forced to implement value-adding techniques in their production management. Many companies begin their improvement efforts without considering the need for a comprehensive plan. As a result, their improvement efforts are not carried out in an integrated and complete manner and do not lead to complete and desirable results. The main objective of this study is to provide a framework that proposes a detailed vision of lean implementation in the machine-woven carpet industry, considering the value stream map as a tool to achieve improvement strategies in this industry. This framework... 

In this study, the influence of eutectic modification, grain refining and cooling rate on amount of shrinkage porosity in aluminium A356 alloy were investigated. Modification process for changing the morphology of eutectic silicon from needle like to fibrous like, use in aluminium – silicon alloys. This process often leads to increasing porosity in melt and affect harmfully on mechanical properties. For studying shrinkage porosity, the melt degassed completely to minimizing amount of gas in the melt. For modification, strontium in Al-10Sr master alloy and sodium in NaF salt used and for grain refining Al-10Ti and Al-5Ti-1B master alloys used. To study the effect of cooling rate, three mold... 

Grammar-based software's are the software's that their input can be expressed according to the grammars for example, reverse engineering software's, evolutional counting's, adjustable programming in product line and XML controllers are in this category; so we can use this capability of the software in its testing .In the field of criteria for the test coverage of the grammar-based software, 5 criteria have been offere so far, which contain rule coverage criterion, context-dependant rule coverage criterion, length-n successor coverage criterion, loop-K coverage criterion and full coverage criterian, any of which have benefits and defeats. The first questions which are asked in this field is...