Sharif Digital Repository

Cavitation phenomenon is defined as the process of rupturing of liquid by a decrease in pressure at nearly constant temperature and it is a very complex non- linear phenomenon. Therefore the theoretical and numerical analysis of cavitation is very difficult and even impossible. A high speed cavitation tunnel is designed and manufactured for experimental understanding of cavitation. The effects of cavitation on drag force of several models such as circular cylinder, hydrofoil and wedge with after body were studied. There was a sufficient turbulence provided at upstream flow, during the tests of circular cylinder and hydrofoil within Reynolds number 105 to .Boundary layer on the cylinder is... 

Dense underflows are continuous currents that move down-slope due to their density being heavier than that of the ambient water. This difference between the dense fluid and environment fluid can be due to temperature difference, chemical materials, solved materials or suspend solid particles. In these currents, the effect of buoyancy force is produced by this difference density. In this research, many experiments performed in different flow rates, slopes and concentrations to understand the current structure and turbulence specification of the salt solution density currents and particle-laden density currents. Acoustic Doppler Velocimeter is used to measure the velocity fluctuations. The... 

Special geometrical sections, known as “duct”, which can be installed on merchant vessels stern in order to improve propulsion system and propeller performance, today have evolved considerably. The force which produces by the propeller depends on efficiency of propulsion system. In the way of improving the efficiency of propulsion systems, by using these special geometrical sections, to much research have been done from the mid-twentieth century. The Wake Equalizing Ducts (WEDs) in addition to conduct the more uniform fluid flow to the propeller disk (which causes to improve the propeller operation), affect on flow separation in ship stern zone and will decrease the separated flow zone.... 

At major-minor intersections with no timing and signal control, with comparison to those with signal control, a lower level of control is imposed on intersection’s traffic. So the driver’s behavior has more effective and important role on geometric and traffic design of intersection. Therefore, recognizing drivers’ behavior at this kind of intersections seems to be vital. In this research drivers’ behavior in big cities in Iran at major-minor intersections has been studied. For this purpose, 7 major-minor intersections which have stop control at minor approach and median at major approach have been selected and shot. After extraction of primary data from taken digital video films and... 

As petroleum resources are not steadily distributed in the world and all industries and manufacturing sections are dependent on these resources, petroleum transportation is very important to the extent that availability of these resources occurs in the fastest time and costing the least possible. The objective of this study is to study the petroleum distribution through time in the world and assess its transportation efficacy during 1965-2005 in 173 countries. Collecting information about petroleum distribution between exporting countries to importing ones helped to complete the study data base. Also in this study two transportation networks, sea and land multimodal transportation network... 

Considering the extensive developments achieved up to now in the fields of trade and international transportation, as well as the key role of the freight transportation in the economical development of a zone or a country, the present research, titled “A Study of the Trade and Transportation Trends”, was planned. The available data concerning the trade of six types of the goods according to The United Nations Classification (SITC), within the period 1965-2005, have been analyzed in this research. The study has been focused on the Asian Multimodal Network constituted of 31 countries. Trading centre of each country in the selected network is assumed to be located in its capital town. The... 

Diabetes is one of the most prevalent chronic diseases. Blood glucose control provides diabetics with the opportunity to keep their normal lifestyle, being a productive resource in the society, while ignoring to do so impose a huge cost to the society. Hence, it is of vital importance to find an appropriate approach to control and prevent the subsequent complications of diabetes. One of the most effective approaches is self monitoring of blood glucose (SMBG), which is now available through the commitment of a number of medical equipment companies to introduce SMBG products to the market. Some of the noted companies appointed Iran medical equipment market as a target for their market... 

Although rural inhabitants constitute a large portion of developing countries’ population, they have always been neglected in many ways. Expansion of equity, calls for a new concern in adequacy of rural development. The problem could be considered in two aspects: Firstly, there is a great tendency for immigration to nearby cities, hoping for a better life. This would result in more crowded cities, extended poverty and an increasing rate of crime mainly in suburban areas. On the other hand, the evacuation of farms and fertilized lands imposes great economical loss to the country. Therefore, development of rural facilities should be integrated into national policies to assure a homogeneous and... 

One of the methods that have been used in order to mitigate the air pollution problem is the IM program in order to identify the high polluting vehicle and make them to adjust their engine in accordance to the emission standards. In Iran due to the air pollution problems the government operates a rudimentary IM program based on the idle engine test utilizing an exhaust gas analyzer which should be done annually. While IM programs usually regarded as a useful tool for soothing the air pollution, one of the criticisms about the program is that it is required for the entire fleet and it reduces the cost effectiveness of the program. This research studies the relationship between the vehicular... 

Increasingly adopting of multiple channels by companies in order to achieve greater market coverage and more sale, has made managers to deal with a new challenge of avoiding conflict in multiple channels. The importance of the issue and lack of empirical research provided motivation to study approaches to minimize multiple channel conflict and explore how they reduce conflict. Therefore a qualitative study using a single case (Solico Group) was conducted. After reviewing the literature 7 approaches were identified to minimize multiple channel conflict: Superordinate goals (goals that achieving them requires efforts and resources of more than one channel), Brand (using products with different... 

The Study of antecedents and considering the status of Project-Based Organizations (PBOs) in our country such as MSA, Azarab, Sadad Machine, etc indicates that they are facing lots of problems in different aspects. This bad situation is in a way that amendment of part of sections guarantees the continuity of bad performance of these companies and we have to apply Business Process Reengineering and establishing a radical change in these firms. So the present research according to managers and experts opinions, several year observations of the writer and review of the literature of BPR, Project Management (PMBOK) and PBOs; and based on a library research, introduces the processes of PBOs in 3... 

Growth of cities leads to neglecting of travel behavior of nomads, although they are an important portion of Iran’s population. The aim of this study is recognition and studying transportation demand in a nomadic society that their households are mostly farmer. Firstly, the theory of activity-based modeling was studied. Sequential modeling was chosen for modeling which consider daily activities of each person as a result of five sequential decisions: a) Choosing daily activity pattern; b) Choosing primary tour time; c) Choosing primary tour mode choice; d) Choosing secondary tour time; e) Choosing secondary tour mode choice. In order to collect pertinent information and conduct survey,... 

This study aimed to shed some light on travel behavior in tourist villages in Iran. Rural areas need efficacious transportation infrastructures and services to promote sustainable development and to avoid urban migration. By exploring the behavioural aspects of rural transportation, their transportation needs and demands can be effectively determined. Subsequently, accessibility and mobility of rural residents can be provided in a sustainable manner. In recent years, tourism has transformed lifestyle and behavior of some rural inhabitants. Utilizing secondary school students in Niasar, a simplified questionnaire was used to collect person and household data. Socio-economic, activity and trip... 

Although villagers and nomads are an important part of Iran's population, the growth of cities has led to neglecting them and their needs including traveling and transportation needs. The aim of this study is to recognize and to study the transportation demands in a pastoral nomadic society. For this purpose, the theory of activity-based modeling was studied. Sequential modeling was chosen which considers the daily activities of each person as a result of five sequential decisions: a) choosing daily activity pattern; b) choosing primary tour time; c) choosing primary tour mode choice; d) choosing secondary tour time; and e) choosing secondary tour mode choice. In order to conduct a survey... 

Due to increasing air pollution and traffic jams, cities are trying to promote non-motorized modes of travel. Therefore, people are encouraged to take ad-vantages of walking to decrease usage of motor vehicles and to enhance their health. Knowledge about pedestrain behavior helps planning and provision of efficious facilities for walking. To address the issue, it was decided to examine pedestrains behavior in Tehran Bazaar. The vicinity of Tehran's old Bazaar is considered to be one of the populous, important commercial centers of Tehran and one of the most spacious footpaths. Behavior analysis is done in both macroscopic and microscopic levels. In the macroscopic analysis the re-lationship... 

Humic compounds are considered the most portion of natural organic matter (NOM) found in many surface water sources.Humic substances have been known as precursors to disinfection by-products.because conventional treatment process can not meet disinfection by-product standards,novel method have been increasingly applied for the removal of disinfection by-products precursors.The〖UV/TiO〗_2 process is one of the advanced oxidation process using the photocatalytic technology.The most important advantages of this process are its stability and high efficiency removal.The present study aims to investigate the effect of 〖UV/TiO〗_2photo-catalytic technology on removal of humic substances.In this... 

Incidents are one of the main sources of delays and they have significant influences on road safety and congestions, air pollution and trip costs. In the time of an incident occurrence, minimizing the response time is essential for several reasons. The most important issue is providing aid for the injured. The faster the persons who are severely injured receive aid, the higher their chances are to be rescued. Also, if the rescue crews get to the incident scene faster the clearance procedure would be accomplished faster and this would result in fewer disturbances in traffic stream and lowering the probability of secondary incidents occurrence. Automatic Incident Detection, AID, has been... 

In railway transportation network, there are spots that we have to intersect with highway network. These intersections break into two branches named grade crossing and unlevel crossing depend on their structure. Grade crossings from the view of protection are grouped into protected crossings and unprotected crossings. Protected crossings depend on their traffic control devices are categorized into active crossings and passive crossings.There are many factors that influence highway-railroad grade crossing design. Some of these factors can vary widely by drivers' behavior. These factors have been developed in models by AASHTO and its publications and shaped like we have them today. In order to... 

Compared to systematically signalized intersections, in the absence of any systematic instruction or signalization at unsignalized-prioritized intersections and due to lower levels of control, driver performance strongly steps in as a decisive factor of intersection traffic and geometric design. Therefore, the study of driver behavior at these intersections appears necessary. This thesis aims to study driver behavior at four prioritized intersections where the minor stream has to yield right of way to the main stream in the city of Mashhad, Iran. Following extraction of raw statistical data from extensive filming, the initial database was constructed consisting of 29 variables. Based on the...