Sharif Digital Repository

This research deals with a realistic cyclic three-stage supply chin consisting of one supplier, one manufacturer and one or more retailers, in FMCG environment. Orders from retailers are supposed to iterate over cycles and parallel machines are available to process perishable jobs with given release dates, due dates and deadlines. To start process of he jobs, perishable raw material, supplied by an external supplier, is required. Jobs are subject to post-production shelf life limitation and must be delivered to retailers during the corresponding time window bounded by due dates and deadlines. Both early and tardy jobs are penalized by partial weighted earliness/tardiness functions and the... 

In the 1950s, Abrikosov predicted the mixed state in superconductors (type II superconductors) which lead to a Noble Prize in 2003 with the experimental verification by shubnikov. Mixed-state is a network of magnetic flux lines with quantized flux (vortices) in superconductors. High-temperature superconductors are of Type II which the existense of vortices in a significant part of the temperature-field phase diagram of them, is an obvious phenomenon. These superconductors provided a proper context for understanding physical phenomena related to vortices and access to experimental data to compare with those provided by statistical mechanics. Vortices can move inside the superconductor by the... 

Dissemination of an analyte under the laminar flows plays a major role in measuring and assessment of biological fluids such as sample preparation in the context of microfluidic systems. Due to the development of manufacturing technology in the Lab-on-a-chip devices, the production of rectangular microchannels with finite aspect ratios and micron and submicron sizes has been provided by which the effect of electrokinetic phenomena on concentration distribution will be magnified in these systems. On the other hand, these biofluids are viscoelastic and show extraordinary flow behaviors, not existing in Newtonian fluids and adopting appropriate constitutive equations these exotic flow behaviors... 

Environmental flows are seldom independent of plants impact. Aquatic canopies are mostly submerged and flexible; this causes a significant impact on Hydrodynamics of flow and mixing structure. Experimental and analytical investigation of vertical mixing in vegetation canopies with flexible submerged vegetation is the aim of this study. Most of the previous studies on flexible submerged vegetation were conducted to study the transverse and longitudinal mixing. In this study, flexible submerged vegetation in the density range of 2.8% to 4.2% was used to study the vertical mixing.The concentration profiles at four separate stations were obtained by image processing. The results for the... 

Preparation of binary polyamide 6 (PA6) / carbon nano tube (CNT) and ternary PA6 / EPR-g-MA / CNT has been carried out using melt mixing. Four PA6s were selected with different viscosities (and molecular weights) and molecular structures (linear or branched). Effect of CNT content (up to 2 wt%) and mechanical mixing conditions (rotor speed, temperature and time of mixing) have been investigated. Ethylene- propylene rubber grafted maleic anhydride (EPR-g-MA) was selected at 20 wt% as toughening agent for ternary nanocomposites and mixing sequence of PA6 , EPR-g-MA and CNT has been investigated. Morphological observations showed that dispersion of CNT is done by erosion mechanism at low melt... 

This thesis tries to suggest a simple solution to reduce the amplitude of occurred fluctuations in mixing tees. Temperature fluctuations can induce cyclical thermal stress and thermal fatigue. In order to estimate the lifetime of pipeline material and reduce the frequency and amplitude of these fluctuations, an accurate diagnosis of these fluctuations must be conducted. For this aim, a comparison between Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models was carried out to show the ability of LES model in prediction of temperature fluctuations. The effect of Peclet number on the amplitude was discussed. The effect of placing simple pipe segments and orifices to... 

Supply chain management involves making integrated decisions by suppliers of primary materials during supply chain until consuming the product by final costumers. This procedure is made up of three main decisions: supply selection, production, and distribution. Selecting supplier is an important issue in making decisions, which consist of qualitative and quantitative factors to determine the suppliers with highest potential to provide company requirements with an acceptable cost. In this study, a retailer is considered in contact with some suppliers. The retailer is willing to purchase some goods form high potential suppliers. Each supplier has a fixed delivery time which differs from... 

Ambient Intelligence is a new paradigm in information technology that creates environments able to detect and respond to users needs, actions, behaviors and feelings. In the presence of interaction conflicts, user trust plays an important role in accepting Ambient Intelligence environments for living, working, etc. Our main hypothesis is that higher conflict density results in a greater loss of trust in mixed-initiative Ambient Intelligence environments. In this thesis, we propose a comprehensive research method for measuring trust in Ambient Intelligence environments using both crowdsourcing and university surveys. We conduct both web-based experiments and physical experiments to gather... 

Kanban inventory system has been applied as a tool of implementing lean production and just in time philosophy since three decades ago. By implementing kanban in supply chain which consist of suppliers , producers , distributors and consumers, real information of demands transfers upstream and materials flows downstream and integrated supply chain can be optained. Therefore a lot of mathematical models for optimizing kanban inventory system in supply chain has been developed to implement just in time philosophy and reduce total inventory cost in supply chain systems this research consist of two main section. In the first section , kanban and supply chain primary concepts are reviewed and... 

In many regions of Iran, arid and semiarid climate and increase of water consumption, lead water managers to use optimal operating of water resources systems. During periods of drought, when inflows to the reservoir are low, it may not be possible to satisfy the target delivery (planned demand), and shortage occurs. Also, During periods of drought, the underground water resource’s pollution and inordinate consumption of underground water resources, increase density of water pollution. These reasons always appoint water resource planner to develop models for determine optimal surface water resource operating rules. Using of hedging rules that are attended by many researchers in these... 

Membrane bioreactor (MBR) is a combination of conventional activated sludge (CAS) and membrane filtration which owing to its advantages such as high quality effluent and low excess sludge production, has gained increasing application in wastewater treatment. The major drawback of a MBR is the membrane fouling that reduces the permeate flux, which in turn increases the overall operational costs due to high energy requirements. In existing study, the combination of sludge oxidation and coagulation/flocculation addition was investigated for mitigation of membrane fouling in a membrane bioreactor. Oxidation can facilitate sludge flocculation and hence improve the properties of mixed liquor. The... 

Fulfilling the demands of customers, used to be the main purpose of Supply Chain Network Designers. Soon after that, the environmental concerns created the concept of Reverse Logistic in order to prevent goods from being scattered in the environment after their disposal. Governmental regulations and people's concerns, forced the factories to gather the created pollutions of the environment. They gradualy confessed the positive impacts of these ruturns on their financials. The flow of forward and reverse logistics establishes a Closed-Loop in which the returning economical circumstances were transferd into original factories. Later, Open-Loops were created. In open-loops the returns have to... 

Operating rooms has always been considered as one of the most expensive, yet most profitable part of a hospital. Since many units in the hospitals are related to the operating room, improving efficiency in the operating room will result in increased efficiency in other units, so offering proper solutions in this area is very important. Suitable Planning and scheduling has a great impact on increasing the level of service and efficiency of the hospital. in this thesis, a mixed integer programming model for scheduling weekly elective patients in the surgical theater with the objective of maximizing the number of elective patients for the surgery and also the workload of the operating room... 

The buzz phenomenon is the shock oscillation ahead of the supersonic air intake when its mass flow rate is decreasing at subcriticaloperating condition. This phenomenon may cause combustion extinguishing, thrust loss and structural damages. To delay the buzz onset and reduce the amplitude and frequency of the buzz oscillations, the method of boundary layer suction has been proposed and studied in this research. The intake has been designed for a freestream Mach number of 2.0, however, wind tunnel tests have been conducted for freestream Mach numbers of 1.8, 2.0, and 2.2. All tests were performed for zero degrees angle of attack. For studying effects of the parameters of boundary layer... 

Reviewing the literature on air traffic flow management shows that reducing flight delay is one of the main challenges facing air transportation systems. This is due to the high cost of incurring delays. At the first stage, two mixed integer-programming model is presented here that aims to minimize delay cost of air traffic. The first presented model seeks to minimize flights delay costs by choosing an optimal airport configuration and balancing departure and arrival flights and the second presented model solve this problem with the new approach with categorizing the airplane by types and prioritizing them. Numerical examples are solved in CPLEX 12.6 to evaluate models performance. Numeric... 

Mass transfer and axial dispersion coefficients for continues phase were calculated by axial mixing model for continues phase and forward mixing model for dispersed phase simultaneously. Experimental data was achieved in pulsed sieve plate column with 22 cm diameter. Toluene –water-acetone and Butanol-Succinic acid- water were used in this experiment. In these systems continues phase is water and mass transfer takes place from continues phase to dispersed phase. Experimental data involves drop size distributions and operating conditions andconcentration in both phases.For calculating overall mass transfer coefficient for drops the handlos and Baron Model was used. The axial dispersion... 

In this thesis, we consider the problem of scheduling parallel batching machines with different machine capacity and jobs of arbitrary sizes and processing times. The machines have identical processing velocity. The jobs are processed in batches given that the total size of jobs in a batch cannot exceed the machine capacity. Once a batch starts processing, no interruption is allowed until all the jobs are completed. First we present a mixed integer programming model of the problem. We show the computational complexity of the problem, and then we propose two heuristics, LPT-BF and LPT-FF with regard to constraints of problem. Finally, we generate different scales of instances to test the... 

Advanced reservoir characterization methods can yield geological models at a very fine resolution, containing 1011-1018 cells while the common reservoir simulators can handle much fewer numbers of cells due to computer hardware limitations. The process of coarsening the fine-scale model to simulation models is known as upscaling. There are three fundamental steps in the procedure of upscaling, i.e. defining the coarse grid geometry, calculating the average properties for the generated coarse grid and simulation of the two-phase flow equations on the generated coarse-scale model. In this thesis, the focus will be on investigating the applicability of optimization in the context of coarse grid... 

Lattice modeling is one of the most effective methods of simulation of crack initiation and propagation in heterogeneous materials. In this method, not only the impurities can be modeled in detail, but also micro crack initiations and crack ramifications can be observed. Lattice model simulations have shown remarkable results in both force-displacement charts and visual crack formations in heterogeneous materials, especially concrete. Simulation of mechanical behavior of concrete has always been a controversial issue in lattice modeling; and, so far, many researchers have proposed different methods. However, high computation demands, has preserved researchers from any major work on the... 

In this project, the continuous phase mass transfer and backflow coefficients are optimized, using the experimental data from two RDC columns. The continuous and dispersed phases are modeled by stage wise and forward mixing model, respectively. Genetic Algorithm is applied to find the optimized parameters of the model. Olney model is employed to find the slip velocities of drops. The dispersed phase mass transfer coefficients were calculated using Handlos-Baron model. In the other part of the project, the Rigid Drop model was modified to predict the mass transfer coefficients of dispersed phase and the modification parameter was optimized by genetic algorithm. The effect of rotor speed and...