Sharif Digital Repository

In this study, polyelectrolyte-coated magnetic silica nanocomposites were prepared via the covalent attachment of polyelectrolytes onto the as-prepared magnetite-silica particles with core-shell structures and average diameter of 210±50 nm, and subsequently applied for the immobilization of lipase molecules. In this regard, polyethyleneimine (PEI) with two molecular weights of 10000 and 750000 and polyacrylic acid (PAA) with two molecular weights of 1800 and 100000 were utilized. The type and molecular weight of the polyelectrolyte molecules greatly impacted the concentration of binding sites on the particles surface and consequently on the lipase immobilization efficiency and loading... 

In this thesis, coupled trajectory and attitude control of an exoatmospheric interceptor is investigated. The interceptor is considered to track and intercept orbital targets in its terminal phase using an infrared strapdown seeker. Attitude control system uses its thrusters in order to keep permanently the detector toward the target in both elevation and azimuth directions. Detector is attached to the body. Divert thrusters generate acceleration perpendicular to the longitudinal axis of the interceptor to correct the trajectory. It is assumed that the interceptor has mass asymmetries. Transltional and rotational dynamics are coupled. Therefore, in order to improve the performance of... 

This research aims to identify dynamic behavior, determine stability properties, and choose an appropriate control method for nonlinear time-periodic (NLTP) systems by using the optimal design approach. The primary objective is to address the challenges associated with these systems, particularly in making them smarter and more autonomous, while acquiring the knowledge needed to overcome these challenges. In this respect, multi-body modeling and nonlinear simulation of a mono-wing, as a modern NLTP micro air vehicle, are initially developed. A trade study is performed in free-flight conditions based on sensitivity analysis of parameters such as initial conditions, geometry, and mass... 

One of the most important methods of controlling discharge in water industry which is widely used in irrigation, water distribution, waste-water engineering, drainage, flood control and other water related projects, is side weir. The hydraulic behavior of flow over side weir is spatially varied flow with decreasing discharge. Various investigators have related the weir discharge coefficient as a function of main channel upstream Froude number and the fraction of weir height to upstream depth . Performance of sharp crested side weirs with extended length (as labyrinth side weir with asymmetric geometry) has been studied in this thesis. The variables for this study are height of weir ,... 

In qualitative content analysis research with the aim of identifying areas of language impairmenthigh-functioning Persian-speaking autistic children, ten subjects were observed during fifteen training sessions which were the cognitive block of a three-block training program. Each session lasted 90 minutes and was video recorded. Prior to this, focus group interviews with specialists and semi-structured interviews with mothers and parallel to that focus group interviews with mothers were handled all of which were audio recorded. After two levels of initial and second coding, a final list of areas of impairment in the language of high-functioning Persian-speaking autistic children, that... 

With the rapid development in information-communication technologies a huge amount of electronic documents has been produced and increase everyday in the world wide web. According to this wide information environment, summarization is critical for the users who digest this electronic big data. This research proposes two graph-based abstractive models for summarizing the Persian texts. A good summary should cover the overall context and the important subjects, and should be properly readable and coherent as well. Some permanent challenges in automatic text summarizations intended to increase the readability of output text, as well as covering all the main topics, and minimize the redundancy.... 

In the transportation litreture, many different algorithms have been proposed for solving traffic assignment problem based on the user-equilibrium principal.These algorithms are devided into two main groups: Path-based algorithms and arc-based algorithms. In the past, arc-based algorithms has attracted quite attention, but recent scientific progress in the computer science changed this viewpoint to the state of path-based algorithms. Much of the attention has been focused on three particular algorithms: the complementarity (C) algorithm, the gradient projection (GP) algorithm and the disaggregate simplicial decomposition (DSD) algorithm. In this thesis, these three algorithms have been... 

This thesis was an attempt to find the effect of having multi-domain conceptual network on metaphorical creativity. The purpose of this research was to answer the following question: By extending and expanding the mental conceptual network, could one increase their potential creativity; In other words, is expansion of the mental conceptual network one of the parameters of creativity or not.To answer this question, a questionnaire and a test were developped. Through the questionnaire, we divided the sample group into the test and control groups. And the test indicated how creative each individual is.There were three different ways the sample group was divided. The criteria for dividing the... 

One of the ways for semantic modelling of natural languages is to use the distributed representations of words. Formerly in order to produce the distributed representations of words several methods like LSA, LDA and other techniques taken from information retrieval were applied. The main idea presented by these methods is that the whole document consists of one central topic that has become hidden by the words it is made of. These models assign one general meaning to the whole document and do not regard words as semantically independent. However, each of the words of a document have specific senses that these models are not able to reflect. On the other hand efforts done in the field of... 

Contact happens when two bodies collide. Depending on our assumption, it can be considered as a frictional or frictionless contact. Here we have assumed that friction accompanies the contact phenomenon, hence it is called a frictional contact. For modeling contact problems, different procedures can be used such as node-to-node or node-to-surface patterns. Here we want to use the node-to-surface procedure to model the contact problem. The node-to-surface pattern has the capability to model interface behavior between different materials. By using the finite element method through numerical computations and also by applying constraint conditions which are related to contact conditions, we can... 

A semantic role labeler is a software that takes sentences as inputs and identifies the words or groups which have semantic roles such as Agent, Theme, Source, Instrument etc. The correct identification of semantic rols using computers can improve the quality of many natural language processing tasks such as information extraction, question and answering, text summarization and machine translation.Therefore a considerable amount of research has been carried out on this topic. Semantic role labelers normally use features extracted from the syntactic structure of the input sentences. That is why the syntactic representation used has a prominent role in the system's outcome. The research...