Focused Ion Beam (FIB) and Nano-Imprint Forming (NIF) have gained recently major interest because of their potential to enable the fabrication of precision engineering parts and to deliver high resolution, low-cost an...
Focused Ion Beam (FIB) and Nano-Imprint Forming (NIF) have gained recently major interest because of their potential to enable the fabrication of precision engineering parts and to deliver high resolution, low-cost and high-throughput production of fine sub-micrometre structures respectively. Using computational modelling and simulation becomes increasingly important in assessing capabilities and risks of defects with respect to product manufacturability, quality, reliability and performance, as well as controlling and optimising the process parameters. A computational model that predicts the milling depth as function of the ion beam dwell times and a number of process parameters in the case of FIB milling is investigated and experimentally validated. The focus in the NIF study is on modelling the material deformation and the filling of the pattern grooves during the mould pressing using non-linear large deformation finite element analysis with hyperelastic non-compressive material behaviour. Simulation results are used to understand the risk of imperfections in the pattern replication and to identify the optimal process parameters and their interaction.
human community has outgrown breaking the laws of the nature. This has caused serious threat to the nature and hence to the human community itself. Day to day activities of the man creates different kind of waste mate...
human community has outgrown breaking the laws of the nature. This has caused serious threat to the nature and hence to the human community itself. Day to day activities of the man creates different kind of waste materials. These materials are thrown in the surroundings, which creates unpredictable damage to the environment. The matter of management of waste has prime priority in sustainable development. In this paper we mainly discuss various characteristics of waste management systems such as efficiency, sufficiency and consistency. A waste management system is developmental if it generates employment and income to the country. We develop some mathematical models which to ensure the efficiency and developmental characteristics of the waste management systems.
In this work we focus on the simulation of the process of biomass syngas combustion in the industrial combustion chamber directly linked with gasification chamber, where this gas is continuously producing from the bio...
In this work we focus on the simulation of the process of biomass syngas combustion in the industrial combustion chamber directly linked with gasification chamber, where this gas is continuously producing from the biomass. Conflicting demands from the engineers to have rapid results and hints how to ensure the best conditions for combustion of this particular fuel and to lower the emission of pollutants, with simultaneously deep view inside the process and its stability motivates us to use both the RANS and LES techniques of turbulence modelling, compare it and take their advantages. We designed and performed series of 3D numerical simulations of both cold flow and combustion in complex geometry of industrial burner. It seems to us that the proper approach for modelling of biomass syngas combustion is steady flamelets model. Simulations performed with RANS closure are used as the initialisation of LES models, but their main goal is to predict the long-time oscillation of pressure and temperature observed in the working combustion chamber. On the other hand the main goal of the simulations with LES closure is to predict the proper level of short-time behaviour of the flame and local phenomena.
Finite element modelling and analysis is an alternative way to study human fracture behaviour in biomechanics field compared to experimental test in laboratory. The aim of this study is to analyse the stress intensity...
Finite element modelling and analysis is an alternative way to study human fracture behaviour in biomechanics field compared to experimental test in laboratory. The aim of this study is to analyse the stress intensity factor (K) and strain energy release rate (J-integral) when three-point bending test and tensile test are applied on a two-dimensional (2D) cortical bone model developed by using finite element software with different applied loads and crack-to-width ratios. Two methods are used to to evaluate the values of K and J-integral which are Displacement Extrapolation Method (DEM) and CINT method. The values then been compared with other theoretical expression done by other researchers for validation purposes. It has been proved that by using CINT method, the error is very small compared to DEM method. As a result, stress intensity factor values increased as crack-to-width ratio increased and strain energy release rate also increased as crack-to-width ratio and loads increased. It can be concluded that finite element analysis can be used to study the fracture behaviour of human cortical bone. Therefore, researchers can easily study the behaviour of cortical bone using simulation instead of mechanical experiment.
The article deals with problem of human gait modelling. human gait analysis is used for various human identification tasks and for various purposes in medicine. Lagrange equations of the second kind in many research a...
The article deals with problem of human gait modelling. human gait analysis is used for various human identification tasks and for various purposes in medicine. Lagrange equations of the second kind in many research are used to model gait. We use a model of an anthropomorphic mechanism of five links to describe human movements. The mathematical model is implemented in the form of software that uses input data on the kinematics of a real gait. An important result of the study is the creation of an algorithm for calculating model parameters that best reproduce the gait of a particular person. Our approach is based on the application of a genetic algorithm to minimize a new special objective function, which depends on discrete generalized coordinates that depend on time. The dynamic picture significantly improves the quality of the model, which is able to reproduce the subtle features of the human gait.
Recently, the proton exchange membrane fuel cell (PEMFC) has gained much attention to the technology of renewable energy due to its mechanically ideal and zero emission power source. PEMFC performance reflects from th...
Recently, the proton exchange membrane fuel cell (PEMFC) has gained much attention to the technology of renewable energy due to its mechanically ideal and zero emission power source. PEMFC performance reflects from the surroundings such as temperature and pressure. This paper presents an analysis of the performance of the PEMFC by developing the mathematical thermodynamic modelling using Matlab/Simulink. Apart from that, the differential equation of the thermodynamic model of the PEMFC is used to explain the contribution of heat to the performance of the output voltage of the PEMFC. On the other hand, the partial pressure equation of the hydrogen is included in the PEMFC mathematical modeling to study the PEMFC voltage behaviour related to the input variable input hydrogen pressure. The efficiency of the model is 33.8% which calculated by applying the energy conversion device equations on the thermal efficiency. PEMFC's voltage output performance is increased by increasing the hydrogen input pressure and temperature.
Solubility phase diagram which consists of information on solute concentration, metastable and saturation limits against temperature, provides helpful insights in designing crystallization process to achieve desired c...
Solubility phase diagram which consists of information on solute concentration, metastable and saturation limits against temperature, provides helpful insights in designing crystallization process to achieve desired crystal size distribution (CSD). Usually, the design of cooling crystallization process involves high supersaturation level at the beginning of the process in the metastable zone that is bounded by metastable and saturation limits. However, this high level of supersaturation causes an increment in both nucleation and crystal growth rates which induce the growth of the seed crystals as well as unwanted secondary nucleation that produce excessive fine crystals. Mitigation by employing proper temperature trajectory or policy along metastable zone to avoid unnecessary long operational time and fine crystals is needed. Thus, the purpose of this paper is to develop and simulate mathematical model of seeded batch crystallization process for the case of potash alum which is mainly used for purification in water treatment. Dynamic response of such process under open-loop operation for three cooling policies which are natural, linear and cubic is performed for evaluating the effect of different cooling policies on CSD. Simulation results based on the dynamic behaviour for all three cooling policies show cubic cooling policy obtained the best performance by achieving mean crystal size of 420 µm from the targeted CSD at 430 µm, and the mean crystal size for fine crystals is the lowest which is 35 µm compared to linear and natural cooling policies, at 40 µm and 55 µm, respectively. This information is prominent in deciding proper temperature trajectory of optimal cooling policy for potash alum crystallization process.
This paper is the outcome of a small scale fuel cell project. Fuel cell is an electrochemical device that converts energy from chemical reaction to electrical work. Proton Exchange Membrane Fuel Cell (PEMFC) is one of...
This paper is the outcome of a small scale fuel cell project. Fuel cell is an electrochemical device that converts energy from chemical reaction to electrical work. Proton Exchange Membrane Fuel Cell (PEMFC) is one of the different types of fuel cell, which is more efficient, having low operational temperature and fast start up capability results in high energy density. In this study, a mathematical model of 1.2 W PEMFC is developed and simulated using MATLAB software. This model describes the PEMFC behaviour under steady-state condition. This mathematical modeling of PEMFC determines the polarization curve, power generated, and the efficiency of the fuel cell. Simulation results were validated by comparing with experimental results obtained from the test of a single PEMFC with a 3 V motor. The performance of experimental PEMFC is little lower compared to simulated PEMFC, however both results were found in good agreement. Experiments on hydrogen flow rate also been conducted to obtain the amount of hydrogen consumed to produce electrical work on PEMFC.
The paper presents the experimental results obtained on an experimental device where a horizontal rubber wire is stretched by a transversal oscillating force - that is a body with an acceleration sensor attached, plac...
The paper presents the experimental results obtained on an experimental device where a horizontal rubber wire is stretched by a transversal oscillating force - that is a body with an acceleration sensor attached, placed at the middle of it that oscillates freely. A nonlinear model was proposed for the experimental test rig, the differential equation of motion was offered and a series of curves were traced and compared to the experimental ones. One can conclude that the theoretical model certifies very well the behaviour of the real model. An open problem remains the manner of adopting the parameters characteristic to the dissipative element of the system.
System identification or modelling is the process of building mathematical models of dynamical systems based on the available input and output data from the systems. This paper introduces system identification by usin...
System identification or modelling is the process of building mathematical models of dynamical systems based on the available input and output data from the systems. This paper introduces system identification by using ARX (Auto Regressive with eXogeneous input) and ARMAX (Auto Regressive Moving Average with eXogeneous input) models. Through the identified system model, the predicted output could be compared with the measured one to help prevent the motor faults from developing into a catastrophic machine failure and avoid unnecessary costs and delays caused by the need to carry out unscheduled repairs. The induction motor system is illustrated as an example. Numerical and experimental results are shown for the identified induction motor system.
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