Sharif Digital Repository

Identifying the success factors of construction projects is one of the most important issues in project management. Lack of sufficient and comprehensive knowledge of project success factors makes it difficult to control, monitor and operate projects. Therefore, identifying the factors influencing the failure or success of projects according to the type of projects by managers, employers and executives can provide a good framework for evaluating and reviewing project outputs for them. Also, recognizing the success factors of projects can help to manage the appropriate allocation of resources throughout the life of the project. The result of this study can increase the existing knowledge about... 

Rapid growth of technology and the increase in availability of fast communication means caused transportation planners to pay attention to solutions of demand management with an aproach to information technology. Replacement of traditional shopping with internet shopping can be seen as a suitable solution to reduce traffic and polution. Purpose of this research is to probe teleshopping choice and the frequency of doing that, simultaneously, using copula model as the most common aproach of joint models in recent years. In this research, the binary logit model is used to build the model for teleshopping choice and the order logit model is used to build the frequency model. The data sample is... 

The abstract is the most important section of the thesis because many readers limit most of their reading to abstracts, saving in-depth reading for specific theses. It should give the reader a "preview" of what's to come. The abstract should emphasize new and important aspects of the study or observations. The purpose of the abstract is to allow researchers to decide whether or not to read the whole thesis. The abstract is what researchers read first to decide if the thesis is important, interesting, and it allows them to assess the relevance of a thesis to their own research, without having to read the entire thesis. Thus, it is crucial that the abstract both summarize succinctly the key... 

The purpose of this research is to establish a neutron reference field for the calibration of neutron dosimeters based on the beam of the neutron radiography system in the Isfahan miniature neutron source reactor (MNSR). The aim is to address the several limitations, including the inability to achieve a wide range of dosimetry, high uncertainty due to variations in distance from the source, significant scattering, and non-uniformity. To overcome these issues, a linear, stable, and wide-range dosimetry field based on MNSR have been established, characterized and evaluated by using the variations of the reactor power. In the first step of establishing the calibration field, the linear and... 

Due to the high level abstraction inherent in most formal specifications and the need to formally specify and develop nondeterministic systems, such as concurrent, probabilistic, and game-like ones, nondeterminism comes into formal specifications inevitably. As it will be shown in this thesis, after developing programs constructively from implicitly nondeterministic specifications, which have been written in the CZ (constructive Z) specification language, only one of the allowable, specified behaviors will appear in final programs. In this way, the implementer will be provided with only one of the possible implementations that is not necessarily the best one. When the nondeterminism involved... 

Quality Assurance is one of the crucial steps in software production and should be repeated. These days, software companies are using continuous integration (CI) pipelines for building software and controlling software quality. Regression test, is a test which is performed after each change in software, to assess the quality of the software system and its ability to meet functional and non-functional needs. Each execution of this test, leads to infrastructure costs and a waste of time for the software development team. The reason is that the development team has to wait until the test is completed to ensure that the changes are correct. To reduce this cost, methods such as prioritizing and... 

One of the most crucial methods to Ensure correct software performance is testing. On this ground, one of the most critical discussions regarding software testing is the effectiveness of a test suite. Program state coverage is a criterion for determining the effectiveness of a test suite. This criterion indicates the number of program states that are executed for the lines. Since the total number of program states cannot be calculated to measure coverage, this criterion proposes a fixed number of 10 to measure program state coverage. Also, according to calculations for the program state in the execution of each line, the time complexity of this criterion is high. In this thesis, providing... 

Construction of some structures including parks, bridges and leading walls conducted on the rivers in urbanization leads to the change in the form of the rivers and consequently the change in the hydraulic.The response of river to these changes which are in the form of changes in morphologic features seems to pose some threats such as flood, damage to the buildings located on the route, weakening the bridge of highways and aggradation and degradation of the ecosystem. Kan river, one of the biggest urban rivers in the mega city of tehran, has had some changes such as resort purposes, canalization, the change of slip and roughness and intersection with different bridges during recent... 

In this piece of work, a gravity model is suggested as Iranian non-fuel export model to OIC countries. The most important results out of this model are the acquired coefficients of two variables, namely “ECO membership” and “Economic and Trade Freedom of Importer”. At first, we expected that for importer, being a member of ECO would increase the amount of trade with iran. Surprisingly, this is not what we see in a model. In fact, as ECO has not achieved any tangible success in increasing trade between its members, eastern Asian Muslim countries has become an important trade partner for iranians. This result is compatible with other pieces of researches about ECO. “Economic and Trade Freedom... 

Today’s growing interest to the underwater explorations and navigations demands to design appropriate underwater communication methods and systems. However, radio frequencies which are widely being used in free space communications, can’t be a good candidate for underwater wireless communications, due to their sever attenuation in water. On the other hand, underwater acoustic communication has been widely studied and implemented in the past decades, inspired by suitable propagation of acoustic waves through the underwater medium. Nevertheless, acoustic communication systems have limited bandwidth, lower propagation speed and lower security than optical counterparts, which suggests underwater... 

Visible light communication (VLC) uses huge license-free spectral bandwidth of visible light for high-speed wireless communication. Since each VLC access point covers a small area, handovers of mobile users are inevitable. In order to deal with these handovers, developing fast and effective resource allocation algorithms is a challenge. this paper introduces the problem of mobility-aware optimization of resources in hybrid VLC and 5G radio access technologies networks using the T-step look-ahead policy and employing the notion of handover efficiency. It is shown that the handover efficiency can correlate the overall performance of the network with future actions based on the mobility of... 

In present research, a cohesive based finite element model has been introduced to estimate median crack depth during mechanical machining on optical glasses. Development of the machining numerical model has been initiated by investigating the indentation process. Experimental results of this step have been calibrated primary numerical model which has been used in the scratch process. Due to differences between the scratch mechanism and indentation one, mathematical bases fracture formulas and cohesive relations have been developed. After extracting primary result, using them in the scratch model and developing the primary model, ultimately numerical model has been evolved to an abstract... 

The most important researchers’ purposes in superconductivity are achievement of the room temperature superconductivity and to understand the high temperature superconductivity mechanism. Researchers’ goal in to increase the transition temperature by applying pressure, changing oxygen content, different doping, and changing stoichiometry in the families of the high temperature superconductors. In this research, which has been carried out in the Magnet Research Laboratary of Sharif University of Technology, samples of Y3Ba5Cu8O18, Gd3Ba5Cu8O18, and Pr3Ba5Cu8O18 have been synthesized by the standard solid-state reaction technique, the structure, electrical and magnetic properties of the... 

In this study, the viability of handling flue gas streams as a source of CO2 for the thermocatalytic conversion was investigated as a CO2 emissions reduction strategy and an intermittent energy storage solution. A transient mathematical model for dynamic catalyst deactivation was validated with experimental results and then used to study HEX membrane reactor. A simulation-based study of novel Sabatier reactor configurations was performed to study the effect of distributed H2 supply on Ni-based catalyst deactivation and to optimize the production of CH4. First, a heat-exchanger type, actively cooled Sabatier reactor is analyzed using a transient mathematical model to assess its feasibility.... 

Hydrothermal supercritical method is one of the most suitable methods for metal oxide nano powder, ceramics and mineral catalyst synthesis. Metal oxides nanopowder in its pure or mixed form has wide potential application as chemical industrial catalyst, hot Superconductors, magnetic material, gas sensors and car catalyst convertors. One of the most important metal oxides aspects of application is uranium oxide as nuclear reactor fuel is used. In addition, UO2 is selective catalyst for converting methane to methanol process and Decomposition of organic Chlorine material. In Supercritical hydrothermal method done in high pressure reactor with critical to fluid, is new method for the... 

Lithium has 9 isotopes which two isotopes are stable and remaining isotopes are unstable and have half-life. Lithium stable isotopes include 6Li and 7Li that their abundance is 7.53% and 92.47% respectively. Importance of lighter lithium isotope appears for its small cross section against thermal neutron and producing fusion reactors fuel in nuclear industries. Thermal neutron absorption cross section for 6Li and 7Li are 950 barn and 37 mbarn respectively. Interesting of these isotopes in nuclear industry is due to the large difference in the absorption cross section.6Li compounds implied for tritium producing in coat of nuclear fusion reactor with DT fuel. Following tritium is used in... 

Foil gas bearings are compliant surface, self-acting hydrodynamic bearings that use ambient gas as their working fluid. They do not require external pressurization and are typically constructed from several layers of sheet metal foils. In high-speed, high-temperature applications the GFB’s have the advantage of developing higher load capacities than with fixed geometry gas bearings. Since GFB’s have a complex structure consisting of a spring-like substructure with an overlying flexible surface, there exists a great variety of permutations on any given design. At current work presents a 1D model for GFB with couple solving Reynolds and Euler-Bernoulli beam equation. This mean top foil assume to... 

Lameness in dairy cattle is a crucial welfare issue in dairy industry, and over the years scientists are attempting to present a detection method. In recent years it is attracting more attention to make the identification and discrimination of sounds and lames systematic and automatic. Right now, the most hopeful results have been obtained through the measurement of Ground Reaction Forces (GRF) of hooves, and analysis of load distribution between four legs, which seems applicable for wide use in dairy industry. However, the accuracy, validity, and reliability of discrimination is still far from an acceptable point, that is because of a great lack in understanding quantitative effects of the...