Sharif Digital Repository

Splashing in the Peirce Smith copper converter was investigated using the Smoothed Particle Hydrodynamics (SPH) method. A model 50 cm in diameter (one eighth of the actual convertor) was made to verify results. The ffect of air flow rate and the distance of air blowers from the surface were identified as two major contributors to splashing and their effect on splashing was investigated. Using C++ based on SPH method, a model, geometrically identical to the physical model, was designed for simulation and verification of results. It was found that splashing may be reduced by as much as 85% by controlling the air flow rate into the convertor  

In tissue engineering, the development of a tissue essentially depends on supply of an adequate amount of nutrients and the design of a proper biophysical micro-environment for cells. The limitation of the available initial number of cells, expensive substances and time consuming experiments are the main bottlenecks in this type of processes. In this regard, mathematical modelling and computational fluid dynamics simulation (CFD) are powerful tools to identify an efficient and optimized design by providing reliable insights of the process. This study presents a mathematical model and CFD simulation of cartilage cell culture under a perfusion flow, which allows not only to characterize the... 

On-chip phase separation of multiphase microflows at the divergence point of Y-shaped microfluidic junctions is an effective way for integrating continuous microstructured devices. In this study, flow pattern maps of various solvent pairs based on the volumetric flow rates of both phases have been drawn experimentally and compared with numerical prediction to investigate the effective domain for which complete phase separation occurred. Furthermore, sufficient separation of aqueous and organic phases at the end of the microchannel was achieved by controlling the pressure difference at the liquid-liquid interface via loading back-pressure on the organic phase. A mathematical model based on... 

In this paper, we introduce and analyze a mathematical model of a viral infection with explicit age-since infection structure for infected cells. We extend previous age-structured within-host virus models by including logistic growth of target cells and allowing for absorption of multiple virus particles by infected cells. The persistence of the virus is shown to depend on the basic reproduction number R0. In particular, when R0 ≤ 1, the infection free equilibrium is globally asymptotically stable, and conversely if R0 > 1, then the infection free equilibrium is unstable, the system is uniformly persistent and there exists a unique positive equilibrium. We show that our system undergoes a... 

Though wound healing process is well-researched, this area is poorly known. One reason is that all interactions have not been discovered, the main reason, though, is that the involved processes interact in a very complicated manner with nonlinear feedback. Such complex feedback mechanisms can be easily addressed by mathematical modeling. This paper contains a review of the mathematical modeling of cell interaction with extracellular matrix components during the process of dermal wound healing with focusing on remodeling phase. The models are of partial differential equation type and solved by numerical method  

Though wound healing process is well-researched, this area is poorly known. One reason is that all interactions have not been discovered, the main reason, though, is that the involved processes interact in a very complicated manner with nonlinear feedback. Such complex feedback mechanisms can be easily addressed by mathematical modeling. This paper contains a review of the mathematical modeling of cell interaction with extracellular matrix components during the process of dermal wound healing with focusing on remodeling phase. The models are of partial differential equation type and solved by finite element method  

A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogenation method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor... 

Multi-floor facility layout problem concerns the arrangement of departments on the different floors. In this paper, a new mathematical model is proposed for multi-floor layout with unequal department area. Maximising the number of useful adjacencies among departments is considered as the objective function. The adjacencies are divided into two major categories: horizontal and vertical adjacencies. The horizontal adjacency may be occurred between the departments assigned to same floors while the vertical can be happened between departments assigned to any consecutive floors. A minimum common boundary length (surface area) between any two horizontal (vertical) adjacent departments is... 

The kinetics and equilibrium of isomerization reaction of D-glucose to D-fructose have been investigated using a commercial immobilized glucose isomer ase (IGI), Sweetzyme type IT®, in a batch stirred-tank reactor. The batch experimental data were used to model the reaction kinetics using the well-known Michaelis-Menten rate expression. The kinetic model was utilized in a dynamic-mathematical model for a packed-bed reactor to predict the concentration profiles of D-glucose and D-fructose within the reactor. The experimental results for the fractional conversion of D-glucose in the packed-bed reactor of IGI catalyst indicated that the model prediction of the transient and steady-state... 

In this paper we introduce a mathematical modeling tool (called Classic General Model: CGM) for the general problem of hardware-software codesign so that different partitioning algorithms can be easily and quickly developed and compared in this same framework. CGM introduces a simple but efficient model which supports single/multiprocessor, primal and dual approaches, fine or coarse granularity. CGM determines solutions by stating Mapping, Implementation and Permutation arrays. For judging among solutions of a certain algorithm, an Objective Function is defined. After modeling the problem by CGM we have a classic problem: finding the best values for elements of three arrays to optimize the... 

In this research the parallel machine scheduling problem with preemption by considering a constant transportation delay for migrated jobs and minimization of makespan as the criterion i.e., Pm|pmtn(delay)|Cmax is investigated. It is assumed that when a preempted job resumes on another machine, it is required a delay between the processing time of the job on these two machines. This delay is called transportation delay. We criticize an existing mathematical model for the research problem in the literature [Boudhar M, Haned A. Preemptive scheduling in the presence of transportation times. Computers & Operations Research 2009; 36(8):2387-93]. Then, we prove that there exists an optimal schedule... 

In this paper, we introduce a model-based Bayesian denoising framework for phonocardiogram (PCG) signals. The denoising framework is founded on a new dynamical model for PCG, which is capable of generating realistic synthetic PCG signals. The introduced dynamical model is based on PCG morphology and is inspired by electrocardiogram (ECG) dynamical model proposed by McSharry et al. and can represent various morphologies of normal PCG signals. The extended Kalman smoother (EKS) is the Bayesian filter that is used in this study. In order to facilitate the adaptation of the denoising framework to each input PCG signal, the parameters are selected automatically from the input signal itself. This... 

The normal human running has been simulated by two-dimensional biped model with 7 segments. Series of normal running experiments were performed and data of ground reaction forces measured by force plate was analyzed and was fitted to some Fourier series. The model is capable to simulate running for different ages and weights at different running speeds. A proportional derivative control algorithm was employed to grant stabilization during each running step. For calculation of control algorithm coefficients, an optimization method was used which minimized cinematic differences between normal running model and that of the experimentally obtained from running cycle data. This yielded the... 

Recently, with the expansion of environmental issues and raising of customers' awareness, companies are experiencing huge pressure from shareholders and the government for greater compatibility with their environment. Companies and industry owners must implement green operations in their daily activities to be able to keep up with the competitive atmosphere of the environment. One of the most important operations to be implemented is cooperating with green suppliers. In this study, a multi-objective mathematical model is proposed to select suppliers and allocate optimal orders to them in a two-echelon supply chain, including supply and distribution echelons. The proposed model focuses on the... 

An integrated procedure for mathematical modeling and power control balance for a SPA (Split Parallel Architecture) hydraulic hybrid vehicle is presented in this paper. Dynamic mathematical model of the powertrain is constructed firstly, which includes five modules: diesel engine, traction motor, starter, loading pump and accumulator. Based on the mathematic model of control modes a stability analysis is done. For some control modes a Sliding Mode Control is designed, which uses full-states closed-loop feedback. The paper finally illustrates and discusses the results of simulation. The results show that the performance and stability of control modes are proper and a power control strategy... 

Hepatitis is one of the most perilous viral infectious diseases and many people suffer from it all around the world. In particular, hepatitis B is a terribly dangerous disease which may cause severe liver damage or cancer if it is not treated. Recently, several dynamic models have been developed from experimental studies for describing such diseases mathematically. The certainty of these dynamics models is questionable in realistic treatment processes. Thus, the modeling uncertainties should be considered in the dynamics, which necessitates employing robust control strategies capable to overcome these uncertainties. Accordingly, in this research, a control strategy is developed in order to... 

The 3A zeolite is an excellent adsorbent for natural gas dehydration due to low energy requirement in regeneration step and easy operation. To perform a reliable modeling, a good equilibrium adsorption isotherm is mandatory. Accordingly, water, methane, methyl mercaptan (M-mercaptan) and CO2 adsorption isotherms and also the competitive adsorption loading versus temperature are described for the system using molecular simulation and mathematical models. It is found that CO2 competes with water for adsorption on 3A and lower temperature is required for selective removal of water. The mathematical model results showed that M-mercaptan and CO2 quickly adsorb on 3A and capacity of 3A for water... 

In this paper, an Al-Mg-Si-Cu aluminum alloy was exposed to various heat treatment processes and the effect of precipitation hardening on hardness was investigated as a function of time and temperature. It was concluded that the variation in time and temperature can improve the hardness of the alloy. The work revealed that time and temperature play an important role in the precipitation hardening process of the alloy. To achieve the maximum hardness, an optimum aging cycle should be used which is heating at 180-190 °C for 15-18 h. Kinetics studies show an apparent activation energy of 58 kJ/mol. A relationship was derived which can be used to estimate the hardness at a given time and... 

In this paper, two different systems for taking exams through the Internet are described and analyzed. They have been designed and executed in Yazd and Shahed Universities. These systems enable us to take the multiple-choice and descriptive exams. In these systems, the exam questions are prepared by the instructor of the concerned lesson and placed in the system database. The students who have taken that lesson can be connected to the system from wherever they want. After entering their username and password they can take part in the exam. One of these systems has been created on the basis of the synchronous model and another one has been developed on the basis of the asynchronous model.... 

The number of known proteins is increasing every day; tens of thousands have been studied and categorized by now. In this chapter, we propose amodel for protein matching or extracting similar parts of two given proteins. We focus on the computational geometric approach and the graph matching method that are used to model and compare the sequence and 3D structure of proteins. The remainder ofthis chapter is organized as follows. We first have a glance at the related works. There are two major methods used in the literature: Delaunay tetrahedralization and similarity flooding.We explain the required information in the next section as background knowledge, and then propose a new idea in Sect....