Sharif Digital Repository

To understand the impact of predation by different types of predators on the vole population dynamics,we formulate a three differential equation model describing the population dynamics of voles, the “specialist predator”and the “generalist predator.” First we perform a local stability study of the different steady states of the basic model and deduce that the predation rates of the “specialist” as well as the “generalist” predator are the main parameters controlling the existence/extinction criteria of the concerned populations. Next we analyze the model from a thermodynamic perspective and study the thermodynamic stability of the different equilibria. The analysis revealsthat when the... 

Urmia Lake is one of the largest permanent hypersaline lakes in the world. Since Urmia Lake is faced with drying phenomena, the release of dust from its surface is expected. The most appropriate technique on dust storms is the remote sensing technique. One of the most popular parameter that provides the integrated information over a vertical column of unit cross section of this phenomenon is aerosol optical depth (AOD). Satellite remote sensing has been used to retrieve AOD over land and ocean at spatial resolutions of several to several tens of km. However, higher spatial resolution aerosol products for local scale areas have not been well-researched mainly due to the difficulty of... 

Today, tens of millions of people on the planet suffer from heart disease. For the correct diagnosis and treatment of these diseases, there is a vital need for accurate scientific evidence such as various types of vascular and cardiac imaging. One of the applications of guidewires is in cardiovascular imaging. Of course, in addition to diagnosis, this device is also used in the treatment of disease. It should be noted that about 21 million central vessel catheters are performed annually on heart patients, of which about 16 million are performed using the seldinger method. Reportedly, unfortunately, 5% to 19% of these operations have had side effects and harm to the patient or failure.... 

Microservices is a software architecture in which applications are divided into a collection of small, independent services. Each of these services is responsible for a specific part of the application's functionality and is developed, implemented, and run independently. Microservices emerged as a solution to the problems in traditional monolithic architectures. Today, microservice is known as the main candidate for building scalable cloud-based systems. In this architecture, a system is built using the integration of a number of microservices. This architecture is defined by two approaches in terms of the workflow model; In the first approach, the model of workflow and interaction between... 

One of the novel methods of stabilization of nuclear waste is the use of vitrification technology. In order to stabilize high level wastes (HLLW) in glass, it is required that the elements are in their oxide form. Therefore, it is necessary to evaporate the waste and turn it into a solid form so that the elements can be converted into oxide form in the calcination furnace. Hence, one of the challenges of stabilization is the optimization of evaporation and calcination conditions. In this research, the parameters affecting evaporation were first investigated. Using laboratory measurements of application: temperature (110 to 180 °C), presence of nitric acid (0.5 to 4 mol/L), ratio of zirconium... 

One of the most common spinal surgeries involves spinal fusion or vertebral fixation, which is used to treat various conditions such as intervertebral disc disease, scoliosis (lateral deviation of the spinal column), fractures, infections, or the presence of tumors in the spinal column. In this surgical procedure, the use of pedicle screws and titanium rods prevents motion and friction between two vertebrae. Screws may enter the vertebrae in the wrong position and angle, causing bone weakening, rupture of nerve roots or blood vessels, weakness or lack of sensation in some parts of the body, spinal cord injury, and in severe cases, paralysis of the patient. For this reason, fusion surgery is... 

Due to the rapid development of computer networks, security is a major concern. Methods of intruding computer networks are also rapidly developing, and there is a new method every day. These facts corroborate the need for new and more intelligent mechanisms for detecting intrusion. To detect intrusion, one must analyze the network traffic. The most used traditional methods of traffic separation are port-based and payload based detection. The former is not so efficient, and the latter is not only inefficient but also violates the privacy of users. Unsatisfied by such methods, researchers adopted machine learning techniques and tried to develop new solutions for detecting intrusion. Methods... 

The construction is classified as a high-risk industry. The number of casualties and fatalities in this industry is disproportionately high. The ability to recognize hazards in the construction process and the design stage is still in its early stages of development. The most important way to control and eliminate hazards and accidents is to analyze these hazards before they occur and plan to deal with them before starting project activities. Identifying safety risks is the first step in evaluating and analyzing these risks. Building Information Modeling (BIM) technology, due to the consideration of the relationship between the elements in the model and because it contains an object-oriented... 

process design and decision-making about it are challenging activities that involve optimizing conflicting goals such as cost, technical feasibility, and environmental impacts. These conflicting goals can be analyzed by considering the complete life cycle of a process or product in the initial design and decision-making. Life cycle analysis follows the environmental effects throughout the life cycle of a product, including extraction, transportation, production, consumption, and disposal. Life cycle assessment includes four fundamental stages: goal and scope definition, inventory analysis, life cycle impact assessment, and interpretation of results. The aim of this project is to investigate... 

If the reservoir temperature lies between the critical temperature and cricondentherm of the reservoir fluid, the reservoir is classified as a retrograde gas-condensate reservoir. When the pressure is decreased on these mixtures, instead of expanding or vaporizing as might be expected, they vaporize instead of condensing. If the reservoir pressure is above the upper dew-point pressure, the hydrocarbon system exists as a single phase in the reservoir (region 3). As the reservoir pressure declines isothermally during production from the initial pressure to the upper dew-point pressure, the attraction between the molecules of the light and heavy components move further apart. As this occurs,...