Sharif Digital Repository

In this study, the heat and mass balance of rotary kiln of iron pellets induration was simulated. Due to large amount of heat transfer calculations, a quasi three-dimensional model has been used in this study. First, the freeboard heat condition was simulated via fluent program and the average temperature of freeboard was stablished. Then, a one-dimensional heat transfer model was developed using heat transfer equations. In this model, the heat transfer via conduction, convection and radiation in different parts of the kiln was included. Also, the bed reactions and their effect on bed temperature were evaluated. Finally, transversal movement and velocity of particles was studied. Transversal... 

mazandaran cement co.( the second biggest cement company in Iran) is located in Mazandaran province north of Iran. Thesis is about the weakness and strength points of available maintenance strategy (which is mostly CBM) in this company and offers some remedies to enhance the current maintenance situation. Maintenance information is assessed over a period of two years in a row and turn into some informative charts and diagrams for easier exploration. Eventually, some solutions are suggested for omitting shortages in current maintenance strategy  

Gas injection is one of the most common methods to enhance oil recovery. But due to the low viscosity and density of gas, viscous fingering and gravity over ride usually happens which lead to reduction of gas injection performance to oil production. Foam injection is one of the techniques that has the potential to improve oil production by increasing. Foam apparent viscosity is higher than gas and its liquid which is made from it. So it can increase sweep efficiency and enhance oil recovery. However, presence of oil can destabilize foam. Beside, salinity has different effects on foamability and foam stability. Foam stability in high saline environment is a challenge. Therefore, the stability... 

Nowadays, application of ultrasonic wave technology as a novel method of enhancing oil recovery and also gas an oil well stimulation is prevailing. Not only this method is environment friendly, but also it is economic. Although the application of this method is proved to be of outstanding positive influences in field operations, it suffers from lack of knowledge about the main governing mechanisms and also there are few mathematical models describing the process. In this study it is intended to investigate the role of ultrasonic waves on rate of recovery and the total recovery from porous media. A model is proposed which can predict the recovery at different times of operation. The results... 

Obtaining polymers with desired properties is very important from industrial point of view. Weight average molecular weight and polydispersity are two important polymer properties. It is also important to obtain a high monomer conversion. In this thesis production of polyvinyl acetate is considered. Under special conditions, the vinyl acetate reactor dynamics become oscillatory which makes the reactor control difficult. For obtaining polymer with desired properties, an objective function which includes weight average molecular weight, polydispersity and monomer conversion has been defined. Then by minimizing this objective function the optimal temperature trajectory is obtained. In this... 

With the growing deployment of host and network intrusion detection systems, analyzing generated alerts from these systems becomes critically important and challenging due to its complexity and high amount of data. A perfect intrusion detection system would be able to identify all the attacks without raising any false and non-relevant alarms. Unfortunately, false alarms are commonplace in intrusion detection systems. Non-relevant alerts, which are associated with attacks that were not successful, are also common. The process of identifying false and non-relevant alerts is called alert verification. Also nowadays, web applications are widely used in critical and important roles (e.g.,... 

Infectious diseases have always been a threat to mankind, and is the greatest causes of death of children and young people. Although this type of diseases is a serious threat to public health; the allocated resources in responding to a semi-large pandemic is inadequate. Therefore, it is important to spend the resources in the most effective and efficient ways to improve pandemic response capability. That is why considerable research be devoted to study different aspects of epidemics, and developed mathematical approaches to choose appropriate strategies in pandemic response. Since the epidemic models are simplified means to describe the transmission of disease, researchers often use these... 

Presently, numerous patients die each day while they are awaiting life-saving organ transplant. Despite advances in medicine and technology, and increased awareness of organ donation and transplantation, the gap between supply and demand continues to widen. Therefore, appropriate utilization of donated organs under organ allocation process is vital, and can save several patients’ life. Due to this cause, this study presents a mixed integer multi-period mathematical model to optimize allocation system in an organ transplantation network. The considered network includes donors, hospitals, procurement centers, transplant centers, and patients. The proposed model strives to minimize the overall... 

In recent years there is a growing trend in designing efficient health care systems. The applications of operations research have been instrumental in advancing this growing trend too. The blood management issue has raised concerns for human on the other hand. Blood is one of the vital commodities in the field of health. Despite significant advances in the field of medicine, a suitable replacement for this vital commodity has not been found yet. Collecting and managing the distribution of blood that is discussed in the blood supply chain management, requires careful planning and managing. In this research blood inventory management in hospitals considering the uncertainty of supply, demand... 

Mobile localization development, is the reason for appearance of location-based services (LBS). Be sure of not disclosing the user personal information is the main challenge in LBS. Many different concepts and approaches for the protection of location privacy have been described in the literature which change the query of user to server. These approaches falling roughly into two main categories: centralized and distributed (user-centric). Centralized category includes approaches like “changing query pattern” using encryption on user device, or using an “anonymizer trusted third party”. In such approaches threat of an untrustworthy LBS server is addressed by the introduction of a new... 

The nurse scheduling problem is an inevitable issue in managing of hospital wards. Maintaining high quality of working in hospitals is too difficult in tense and high-pressure work environment. Manually solving the scheduling problem is time-consuming. It can pose problems to considering individual excellence, personnel requests and distributing shifts in a fair and desirable manner. These problems and the impossibility of considering all conditions together made the nurse scheduling as an important scheduling problem. In this research we propose a model to assign nurses to shifts considering regulations and hospital’s policies. Unlike nurse scheduling literature we consider nurses... 

Generally, the costs of logistics and distribution are included in the significant share of the product price. Hence, choosing appropriate decisions and reducing these costs can have an important effect in reducing the price of products and services, increasing the competitiveness of enterprises. One of the most important measures, in order to achieve this goal, is to integrate location of distribution centers and the routing paths of goods. That how these decisions are made in the networks and discrete problems seriously has been taken into consideration but in continuous areas due to the complexity has not been studied a lot by scholars. In this study, we try to develop a model for... 

Given the great importance and urgency of preventive operation against illegal drug trafficking as a social scourge, it is necessary to schedule and optimize the police decision in order to interdict further distribution of this harmful product. In this thesis, we study interdiction of drug distribution as multi-period maximum flow profit network interdiction on a multi-commodity flow and multi-source-sink network. The drug distribution network consists of criminal who are dynamically connected and seek to maximize the total flow profit from sources to sinks while the police aim to reduce aim to reduce total flow profit over long period of time by monitoring and interdicting criminals due to... 

Intensity Modulated Radiation Therapy is one of the most commonly used procedures of delivering radiation to cancerous tissues, with the aim of reaching the prescripted dose in the target volume while minimizing damage to nearby healthy organs. Two decisions are of fundamental importance: to select the beam angles and calculate the beam intensities. Beam Angle selection (Beam Angle Optimization) is an important problem. Due to the large amounts of computational time, beam angles are often selected manually based on human experience and intuition. In this study, three optimization methods –Simulated Annealing, Branch & Prune and Local Neighborhood Search- that are selected among known methods...