Sharif Digital Repository

This research investigates permutation flow shop scheduling problems with sequence-dependent setup times with minimizing the number of tardy jobs as criterion (Fm|prmu, Sijk|ΣUj). A mixed integer linear programming model has been developed for the research problem. As the problem is shown to be NP-hard, several meta-heuristic algorithms based on tabu search (TS) and imperialist competitive algorithm are developed to heuristically solve the problem. In order to find the best meta-heuristic algorithm, random test problems, ranging in size from small, medium, to large are created and solved by the meta-heuristic algorithms. Then, a detailed statistical experiment, based on split-plot design is... 

This research considers coordination of pricing and scheduling decisions in a make-to-order environment. We consider a two machine flowshop environment. The objective is to maximize the total net profit, i.e. revenue minus scheduling cost resulting from pricing and scheduling decisions. Prices of orders are set by the manufacturer and demand is a non-increasing function of price. Two mixed integer linear programming models have been developed for the research problem. As the problem is shown to be NP-Hard, a Metaheuristic algorithm is developed which is combination of two tabu search sub algorithms, one for pricing and the other for scheduling. And to evaluate performance, results from... 

Prediction and identifying of negative stimulus which affect cost and time of project with analyzing them and conducting appropriate response are implemented in project management risk. In risk management process, planning and conducting the project is done by considering the uncertainty and continuous tracking that requires preventing the occurrence of changes with negative outcome and effective response to risks. True decision making is desirable for project oriented organizations and project managers in order to implementation the verity kind of actions in apposite of risk events and also for project planning in as though least negative outcomes arise.
In current dissertation a... 

Control of the product manufacturing and evaluating its behavior during deformation is one of the most important issues in hot deformation, especially hot rolling. One of the factors affecting on quality of hot rolled steel strips is the flatness after run-out table cooling.Distortion in a steel strip results from non-uniform temperature profile as the strip cools to room temperature. Increase in the rolling velocity and subsequently the cooling rate affect thermal stresses. In this study a mathematical model for prediction of austenite- ferrite phase transition kinetics and thermo-mechanical stresses on the run-out table after hot rolling was developed for low carbon ferrite steels.... 

Water flooding is known as a common method to maintain reservoir pressure/enhance oil recovery. The major problem in this process induced from inorganic deposits that caused formation damage around wellbore region. It is due to incompatible nature of injected and formation water which results in permeability reduction and well productivity decrease. Solving this problem is an important issue in the petroleum industry. BaSO4, CaSO4 and SrSO4 are inorganic sediments formed in this process. The physical model of water transport in reservoir and scaling damage due to sediments contains at least two dominant parameters; the kinetics coefficient that specifies the velocity of chemical reaction,... 

The current study was attributed to uranium uptake by Varion-AP resin from Saghand, Iran Uranium Mine, ore leach liquor. A suitable high-efficiency system was designed for continuous ion exchange at the bench scale and the uranium uptake parameters were optimized. In this system, 1 reactors was used with a volume of 3 liters in stage with the same height difference. A leach liquor containing uranium with a concentration of between 200 and 300 mg/l was flowed from the feed storage by gravity between reactor 1 to 10 at a flow rate of 30 lit/h and Varion-AP resin was transferred in counter-current flow from stage 10 to 1 by a pneumatic pump. The output of each reactor had a screener that... 

Liquid flow between two porous blocks in fractured reservoirs can occur through capillary continuity or re-imbibition. Studies have shown that capillary continuity via liquid bridges formed in horizontal fracture increases oil recovery from reservoirs. The critical fracture apertures for stability of liquid bridges, shape of curvature and fracture capillary pressure for prediction of fractured reservoir performance remain as controversial topics. Experimental results have shown that critical fracture aperture is a function of surface wettability and critical Bond number. Capillary pressure of fracture might be a positive or negative value caused by liquid bridges. The best method for... 

Wound healing is a complex biological process dependent on multiple variables: tissue oxygenation, wound size, contamination, etc. Many of these factors depend on multiple factors themselves. Mechanisms for some interactions between these factors are still unknown. In this resarch we try to simulate and control wound healing process with focusing on remodeling phase by neural networks as an intelligence technique. For these purposes some materials like mathematical modeling, finite elements method, and effect of external forces on the scar tissue are used here  

Today cancer is one of the leading causes of death worldwide. It is caused by some cells that they gather together in part of the body and they have an abnormal and very high proliferation rate. Investigations on tumors have shown that when tumor volume increases, oxygen concentration in some regions of tumors decreases and this hypoxic condition leads to some cancer hallmarks, e.g. angiogenesis, deregulation of apoptosis, and shift in cell energy sources. So treatment strategies that can increase tissue oxygenation are good choices for cancers. Hyperbaric oxygen therapy (HBOT) which is used to treat diabetic ulcers and carbon monoxide poisoning, have been used experimentally for cancer and... 

The most important sources in container terminals are berth and quay cranes. The main purpose in the container terminals is reducing delay times of vessels. This will be obtained with planning of terminal sources. This research addresses simultaneous berth and quay crane scheduling problem. A mixed integer linear mathematical model is proposed to minimize sum of completion time of vessels. Since the proposed research problem is NP-hard, two methahuristic algorithms based on Tabu Search (TS) and Particle Swarm Optimization (PSO) are presented to heuristically solve the problem. After parameter tuning, PSO and TS algorithms are compared with experimental design methods. The results indicate... 

A major medical revolution that is helping us overcome some of the worst diseases, including cancer, is angiogenesis, which is based on the processes our bodies use to develop blood vessels. Most human cancers have acquired six essential capabilities: self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, programmed cell death escape, unlimited replication potential, persistent angiogenesis, and tissue invasion that can induce metastasis. In other words, the defense mechanism that prevents any of these acquired capabilities must be neutralized before the cells become malignant and invasive tumors. In fact, tumors in the non-vascular growth stage can only grow up to... 

In this thesis attempted to present practical hydro-aerodynanic model with low computational time and high accuracy for WIG craft with a compound wing, a catamaran hull form and a power augmented ram (PAR) platform at take-off phase. To achieve this innovation, aerodynamic and hudrodynamic model are coupled and dynamic air cushion between demi hull of catamaran under the wing was considered by modeling PAR platform with effect of flap. To validaty the results of hydro-aerodynanic model, two test models were producted and the results of hydro-aerodynanic model are compared with the experimental results that the presented results had good agreement with the experimental results. Influence of... 

Nowadays, with respect to environmental pollution and energy supply, producing gasoline from methanol or syngas is one of the most interesting research subjects. Gasoline production from methanol is a catalytic process that produces high-quality gasoline with minimum unwanted compounds. So this gasoline is a clean fuel and it can be replaced to petroleum gasoline. Because of that, it can be a valuable process in the petrochemical industry. One of the most important aspects of this process is catalyst deactivation with respect to time on stream. Catalyst deactivation is usually caused by poisoning, sintering, blocking pores, and coking. In this research, material and energy balance equations... 

Loop heat pipe (LHP) is a two phase heat transfer device that is mostly used in cooling spacecrafts facilities. In this research a novel LHP is studied analytically and its steady state operating characteristics is analyzed in a one dimensional approach with heat transfer and pressure drop correlations. The novel LHP has a new arrangement in evaporator and reservoir configuration in comparison with conventional LHPs, which results in a different energy and fluid flow. In addition, the novel LHP has a new mechanism for acive control of working temperature. In modeling the proposed LHP the fluid and energy flows are first determined, then proper correltaions for calculationg each energy flow... 

In this research, a mathematical model was developed to simulate a two-phase fluidized bed reactor for oxidative dehydrogenation of propane to propylene. Since the assumption of minimum fluidization condition for the emulsion phase is not realistic , the hydrodynamic structure proposed by Cui et al. was used in this study. The mass balances in unsteady state was obtained in a control volume. The differential equations contain three terms, corresponding to the mass transfer by convection, the exchange between phases and the reaction. All differential equations based upon material balances, hydrodynamics and kinetics for all components were solved numerically using MATLAB software 2010a.... 

An industrial scale reactor for light olefinsproduction was modelledusing the oxidative dehydrogenation (ODH) of light paraffinsin a multi-tubular reactor system involving 10000 small diameter tubes immersed in a shell with proper liquid-cooled flows. Here a theory-based pseudo-homogeneous 1-D model describing the operation of a fixed bed reactor for the ODHparaffinstoolefins over a Ni-Nb-O mixed oxide catalyst (for ethane) and over a V2O5/γ-Al2O3catalyst (for Propane),was employed. The paraffin and oxygen conversions, gas process and coolant temperatures, as well as other parameters affecting the reactor performance, including pressure, were examined. Furthermore, the applied model showed... 

After carbon and hydrogen the most existed element in crude oil is sulfur which is appeared as sulfur compound in fossil fuels. Sulfur might be converted to hydrogen sulfide by hydrodesulphurization operation. The increasing demand for sulfur removal has required large improvements in hydrodesulphurization technology.Most hydrodesulphurization processes use fixed-bed reactors, however, there are still some disadvantages with performing hydrodesulphurization in these reactors. The most important one is high exothermic nature of hydrodesulphurization process which cause some problems for catalyst in these reactors and decrease the performance of catalyst. In order to solve the temperature... 

Polymer membrane fuel cell is a rich source of renewable energy. Two problems of short life and low reliability in fuel cells are the main problems of this system. The difference in partial pressure of hydrogen and oxygen causes serious damage to the fuel cell and inefficiency of the electricity production capacity. On the other hand, the life and optimal performance of the fuel cell depends on the moisture content of the membrane because the membrane needs sufficient moisture to pass ions. Transparent fuel cells can be used to study the water in the fuel cell. With direct imaging of this type of fuel cells, the phenomenon of water creation in the fuel cell can be studied with the help of... 

Environmental and economic scarcity of resources are the most important challenges of industry sector. Iran confronted with lack of sufficient water resources and proper management and faces with drought and its environmental and economic consequences. It is a complicated challenge to provide the water demand without any damage to the ecosystem and it needs to do social, economic and environmental assessments. Wastewater treatment (water recycling) is an alternative option for supplying water demand. Wastewater treatment system (collecting, transportation to the treatment plant, wastewater treatment, and discharge) designed in order to solve hygienic and health issues in first place, but it... 

The growing amounts of generation of electronic wastes (e-waste) and their increasing environmental impacts require a special optimal waste management strategy. Many different methods have been developed to managing e-waste. To make the best choices according to the conditions of each system, having an adequate knowledge of all methods and comparing them is the most important point. This research aims to design a system for managing e-waste by selecting mobile phones as an example of electronic waste and find the optimal condition of the system to increase economic benefits and reduce environmental impact. Recycling and landfill are selected as the main methods in this project. Four lines...