MATLAB Programming Code Research Articles

Theoretical Computation of Electron Density in Laser-Induced Carbon Plasma using Anisimov Model

In this work, electron number density was calculated using Matlab program code and the writing algorithm of the program. Electron density was calculated using the Anisimov model in a vacuum environment. The effect of spatial coordinates on the electron density was investigated in this study. It was found that the Z axis distance direction affects the electron number density (ne). There are many processes such as excitation, ionization, and recombination within the plasma that may affect the density of electrons. The results show that as Z axis distance increases electron number density decreases because of the recombination of electrons and ions at large distances from the target and the loss of thermal energy of the electrons at high distances with the progress of time and at a certain coordinate. The target is carbon (graphite). The results were selected in four dimensions where three of them belong to the spatial coordinates x, y, z and the fourth dimension is the electron density (ne).

An approach for predicting longitudinal free vibration of axially functionally graded bar by artificial neural network

In this study, an Artificial Neural Network (ANN) model is designed for the analysis of the longitudinal free vibration of an axially Functional Graded (FG) bar. The material of the bar is varied from one end to the other end according to power law function. Aluminum and Alumina and the mixture of these two materials are used in the analysis. The radius of the bar is also varied along to the longitudinal direction according to power law function. In addition, the effect of the variation in the slenderness ratio is also investigated. An ANN code is written in Matlab in order to obtain a generalized approach for vibration analysis of the FG bar. In the ANN training, some results of free vibration analysis obtained from the SolidWorks program based on Finite Element Method are used. The predicted values that are not used in the training are also obtained in SolidWorks for comparison. A Matlab program code, which based ANN method is used to find new values to be predicted. The process is also made for comparison with the ANN based Matlab nntool program. When the results obtained from SolidWorks and prepared Matlab code and Matlab nntool are compared, it is seen that the results are in harmony. AMS subject classifications: 74H45, 68T07

Design and Optimization of a Small-Scale Horizontal Axis Wind Turbine Blade for Energy Harvesting at Low Wind Profile Areas

Wind turbine blades perform the most important function in the wind energy conversion process. It plays the most vital role of absorbing the kinetic energy of the wind, and converting it to mechanical energy before it is transformed into electrical energy by generators. In this work, National Advisory Committee for Aeronautics (NACA) 4412 and SG6043 airfoils were selected to design a small horizontal axis variable speed wind turbine blade for harvesting efficient energy from low wind speed areas. Due to the low wind profile of the targeted area, a blade of one-meter radius was considered in this study. To attain the set objectives of fast starting time and generate more torque and power at low wind speeds, optimization was carryout by varying Reynolds numbers (Re) on tip speed ratios (TSR) values of 4, 5, and 6. The blade element momentum (BEM) method was developed in MATLAB programming code to iteratively find the best twist and chord distributions along the one-meter blade length for each Re and tip speed ratio (TSR) value. To further enhance the blade performance, the twist and chord distributions were transferred to Q-blade software, where simulations of the power coefficients (Cp) were performed and further optimized by varying the angles of attack. The highest power coefficients values of 0.42, 0.43, and 0.44 were recorded with NACA 4412 rotor blades, and 0.43, 0.44, and 0.45 with SG6043 rotor blades. At the Re of 3.0 × 105, the blades were able to harvest maximum power of 144.73 watts (W), 159.69 W, and 201.04 W with the NACA 4412 and 213.15 W, 226.44 W, 245.09 W with the SG6043 at the TSR of 4, 5, and 6 respectively. The lowest cut-in speed of 1.80 m/s and 1.70 m/s were achieved with NACA 4412 and SG6043 airfoils at TSR 4. At a low wind speed of 4 m/s, the blades were able to harness an efficient power of 79.3. W and 80.10 W with both rotor blades at the TSR 4 and 6 accordingly.

Chance constraint programming problems with parameters as exponential random variable

Robust decision making under uncertainty is deemed to be a crucial factor in many discipline and application areas. Also management and measurement of risk is an important issue in almost all areas that require decisions to be made under uncertain information. Chance constrained programming (CCP) has been used for modelling and analysis of risks in a number of application domains. This paper presents a deterministic reduction of linear and nonlinear chance constraint programming problem using simple mathematical and statistical tools, assuming the coefficients of the decision variables in the chance constraints as exponential random variables. After converting the proposed chance constraint programming problem into a deterministic problem, standard generic package is used to find the compromise solution and also comparison with some other technique is considered. Then MATLAB programming code is used to verify the validity of solution for the original chance constraints.

Composite coating effect on stress intensity factors of aluminum pressure vessels with inner circumferential crack by X-FEM

In this paper, the fracture behavior of a pressure vessel involving a full circumferential wall crack at the inner surface is investigated by applying the axisymmetric model. By using the extended finite element method (X-FEM), the stress intensity factor is calculated and compared for the case of a crack in the Aluminum monolayer cylinder as well as when the composite coating is mounted on its outer surface. Also, the stress intensity factor is obtained for different crack lengths, materials, and fiber orientations in the composite laminate. The materials of composite laminate are Glass-epoxy and Carbon-epoxy. An axisymmetric extended finite element formulation is developed for the pressure vessel, and a MATLAB programming code is implemented to solve the problem. To validate the developed code, two examples are solved and compared with the available results of two-level finite element method (2LFEM) and exact solutions. The results obtained from the axisymmetric X-FEM model is in good agreement with the existing results. The results show that the most reduction of SIFs occurred in pressure vessels with the Carbon-epoxy coating with 0° fiber orientation.

Maxwell model geotextile encased stone column in soft soil improvement

In the field of geotechnical – soft soil improvement, the mathematical model or mechanical model is one of the important input parameters for the design calculations or studies. The determination of the appropriateness of the models has a great influence on the accuracy results of design and calculation as well as the sustainable stability of soft ground after improvement. On the contrary, the selection of inadequate calculation models will lead to increased costs of soft soil improvement, possibly even leading to the destabilization of the work and causing immense loss of people and property. Recently, many projects major highway after construction design in use has not meet the requirements of the standard, leading to wasted money and time of individuals, organizations, and the state of post-treatment. Therefore, the research and application of using mathematical or mechanical models in accordance with the new soft soil improvement method will greatly help as well as add additional options for soft soil improvement in Vietnam. The soft soil deformation is not only related to load but also to load time. The change in stress and deformation of weak soil over time is called rheology, and in this study is the viscoelastic behavior. From the above reasons, we try to apply a generalized Maxwell model to explain the viscoelastic behavior of a soft soil. In particular, the time-dependent behavior of a viscoelastic soft soil was represented by using the Maxwell rheological model. The Matlab programming code helps to solve numerically all the equation of the mathematical exhibition of the generalized Maxwell model results. We acknowledge that the generalized Maxwell model is superior in demonstrating the time-dependent behavior of soft soil. The results probably show that this is one of the effective models to predict the behavior of soft soils in ground improvement with GEC.

Obtaining the Practical Formula for the Trim-tab Dimensions to Reach the Minimum Drag for Planing Boat

Trim-tab is a device for controlling and stabilizing planing boats in different sea conditions. This paper presents to find dimensions of the trim-tab at various speeds of the boat to reach the minimum drag. The speed of the boat is from15 m/s to 30m/s. Drag of the boat is calculated by Stavisky’s method. The minimum drag is found based on the optimum the trim angle. A Matlab program code is prepared for these calculations and all the all results such as drag, dimensions of the trim-tab, longitudinal center of pressure and time angle at different speeds of the boat are presented and discussed.

Reaction rate ambiguities for perturbed spectroscopic data: Theory and implementation

The analysis of reaction systems and their kinetic modeling is important for both exploratory research and process design. Multivariate curve resolution (MCR) methods are state-of-the-art tools for the analysis of spectral series, but are also affected by an unavoidable solution ambiguity that impacts the obtained concentration profiles, spectra and model parameters. These uncertainties depend on the underlying model and the magnitude of the measurement perturbations.We present a general theoretical approach together with a computational method for the analysis of the solution ambiguity underlying arbitrary kinetic models. The main idea is to determine all those model parameters for which the corresponding pure component factorizations satisfy all given constraints within small error tolerances. This makes it possible to determine bands of concentration profiles and spectra that reflect the underlying ambiguity and circumscribes the potential reliability of MCR solutions. False conclusions on the uniqueness of a solution can be prevented. The procedure can be applied as a post-processing step to MCR methods as MCR-ALS, ReactLab or others. The Matlab program code is freely accessible and includes not only the proposed ambiguity analysis but also an MCR hard-modeling approach. Application studies are presented for two experimental data sets, namely for UV/Vis spectra on the relaxation of a photoexcited state of benzophenone and for Raman spectra on an aldehyde formation process.

Engineering Characteristics and Performance of Polypropylene Fibre and Silica Fume Treated Expansive Soil Subgrade

This study presents the experimental results of the effective utilization of polypropylene (PP) fibre and silica fume (SF) to stabilize the expansive soil subgrade as a possible alternative from the environment, economic, and technical perspective. During the drying cycle, clayey soil undergoes unpredictable shrinkage deformation. The nonrecurring shrinkage behaviour of expansive soil caused the adverse effect on lightweight civil engineering structures. Therefore, expansive soil is not considered suitable subgrade material for paved structure construction. Paved structures constructed on clayey soil subgrade experience severe damages occur in its life cycle. The numerous mechanical, biological, and chemical techniques have been successfully demonstrated to reduce the swelling–shrinkage nature and improve the strength behaviour of expansive soil subgrade. This study aims to utilize industrial waste SF as chemical and PP fibre as a mechanical stabilizer. The mecho-chemical stabilization of expansive soil has been carried out by reinforcing the expansive soil with PP fibre and chemically stabilizing with SF. To evaluate the performance of waste material as a stabilizer, compaction, Atterberg’s limits, free swelling index (FSI), electrical conductivity (EC), pH, swelling pressure, and California bearing ratio (CBR) tests have been conducted on treated and untreated specimens. Over the past few years, images from digital cameras have been successfully used to study crack morphology and various parameters of soils. The image processing technique has been used to evaluate the shrinkage limit by developing the MATLAB program code. The microstructural analysis has been carried out using scanning electron microscopy (SEM) analysis. The varying percentage of silica fume (2%, 4%, and 8%) and polypropylene fibre (0.25%, 0.5%, and 1%) by weight of dry soil were used to stabilize the expansive soil. The results show that the value of CBR increases and the shrinkage area decreases with an addition of SF and PP fibre. The experimental results also show a reduction in Atterberg’s limit with the addition of SF and PP fibre; as a result, the shrinkage behaviour of clayey soil reduces exponentially. The digital image processing technique showed a higher potential to understand the soil morphology for the large area.

Determination of the influence of thermo-mechanical factors on the residual stresses of cylindrical composite tubes: Experimental and computational analyses

The well-established benefits of compressive residual stresses over the fatigue lifetime constantly motivate engineers to scrutinize these trapped stresses in mechanical/civil structures. This research deals with characterization of thermal residual stresses in fiber reinforced polymer (FRP) tubes. Three important thermo-mechanical parameters, namely “cooling temperature”, “CNT reinforcement” and “tube size” are taken into account with the aim of achieving optimum design in manufacturing of FRP tubes. The work includes experimental evaluation of residual stresses coupled with developing a MATLAB programming code and performing a thorough finite element (FE) analysis. After fabricating several hybrid FRP tubes with respect to the mentioned parameters, we measured residual stresses conducting “slitting” semi-destructive method. The impact of either of parameters is then examined and some key points are suggested regarding controlling residual stress in FRP structures. The outcomes of this work suggest that slitting method can practically provide access to the in-depth distribution and through thickness of trapped stresses in the FRP laminates with a good accuracy. It is also underscored that studied parameters could play a crucial role in creation of thermal residual stresses.

Influence of Location and Thickness Variations on Guided Waves in Defective Carbon/Epoxy Plate

This paper addresses the effects of plate thickness and defect location on guided wave propagation in carbon/epoxy plates. A three-dimensional (3D) finite element model (FEM) of the plate was developed using MATLAB program codes, and simulated in Abaqus/Explicit. Referring to experimental ultrasonic C-scan images, the complex impact damage was modelled with irregular-shaped delamination and through-thickness matrix cracks. The simulated results show that a slower arrival time signal and amplitude drop of guided wave captured behind the defective region can be used as an indicator of the impact damage. A largOer scattering occurred when delamination was located closer to the plate surface. The extent of scattering gets larger, especially in the direction of 345o from the excitation point. It is also observed that the impact damage can still be detected through a line scan method across the impact damage, although the wave attenuation is greater in a thicker composite plate. By investigating these factors independently, the trends of the scattered guided ultrasonic waves can be classified and perhaps will revolutionize a smart non-destructive method for composite structure in the future.

On the optimal design of manufacturing-induced residual stresses in filament wound carbon fiber composite cylindrical shells reinforced with carbon nanotubes

Process-induced residual stresses occur in composite structures composed of dissimilar materials. As these residual stresses could result in fracture, their consideration when designing composite parts is necessary. In this research, the residual stresses behavior is characterized in terms of three manufacturing features including ‘environmental’, ‘materialistic’ and ‘dimensional’ features. In experimental part, after the fabrication of carbon nanotubes (CNTs) reinforced composite shells, the slitting technique is employed to measure the released strains. Then, the elements of the stiffness matrix are obtained accomplishing an extensive computational modeling in ANSYS commercial software. The obtained results of experimental and computational parts are correlated using a MATLAB programming code, and residual stresses are calculated by calibration factors. Additionally, a statistical analysis is carried out to analyze the influence of mentioned parameters in overall scale. The experimental results had a good agreement with the analytical ones. Finally, this study highlights the complexity and the multifaceted characteristic of residual stresses development in terms of mentioned parameters in CNT-reinforced carbon fiber composite shells.

Peltier Supercooling in Transient Thermoelectrics: Spatial Temperature Profile and Characteristic Cooling Length.

Thermoelectric coolers (TECs) can reach temperatures below that obtained with a steady-state current by applying an electrical current pulse which enables a transitory state in a Peltier device. This effect is known as supercooling. In this paper, we study characteristics parameters, such as the minimum cooling temperature and spatial temperature profile, in a TEC operated under current pulses and a cooling load . Numerical analysis for a one-dimensional thermoelectric model of the cooling system is developed, and a novel MATLAB programming code is proposed for the transient state based on finite element analysis. We also investigate the influence of the thermoelement’s length upon the cooling mechanism. A new parameter called the “characteristic cooling length” is proposed to describe the length in which the minimum cooling temperature occurs along the elements of a TEM. Results show the transient temperature profiles along the elements of the semiconductor P-type element, and a “characteristic cooling length” is characterized. We also propose a general principle, and the lowest cooling temperature values are obtained for a semiconductor’s small length and variable pulse cooling load under current pulse operation. The present study will serve as guidance for the geometric design of TECs under current pulse operations.

Structural Optimization Coupled with Materials Selection for Stiffness Improvement

Abstract An application of a Finite Element Model updating is presented in this paper. Two Finite Element models were considered: a reinforced plate and a thin-walled beam. The two parts were numerically calculated in ANSYS Mechanical APDL and MATLAB programs. ANSYS performs Finite Element calculations, and a MATLAB programming code was used to control the optimization procedure. Geometric variables were chosen, to evaluate the value of the defined objective function. The material was picked using available selection charts, to find the most adequate one for the study. It has been concluded that the transveral displacement of the models modified by the optimization process decreased sharply in relation to the original state.

A simulation model for public bike-sharing systems

Urban areas are in need of efficient and sustainable mobility services. Public bicycle sharing systems stand out as a promising alternative and many cities have invested in their deployment. This has led to a continuous and fast implementation of these systems around the world, while at the same time, research works devoted to understand the system dynamics and deriving optimal designs are being developed. In spite of this, many promoting agencies have faced the impossibility of evaluating a system design in advance, increasing the uncertainty on its performance and the risks of failure. This paper describes the development of an agent-based simulation model to emulate a bike-sharing system. The goal is to obtain a tool to evaluate and compare different alternatives for the system design before their implementation. This tool will support the decision-making process in all the stages of implementation, from the strategical planning to the daily operation. The main behavioral patterns and schemes for all agents involved are designed and implemented into a Matlab programming code. The model is validated against real data compiled from the Barcelona's Bicing system showing good accuracy.

Thermodynamic and Environmental Assessment of Gas Flaring in the Niger Delta Region of Nigeria

This paper discusses the thermodynamic and environmental assessment of flared gases in an oil field. The oil field for the case study is located in the Niger Delta region of Nigeria. The data required for this report were obtained during a nine-year period (2008-2016), which revealed production volumes, flared volumes, operating temperatures and pressures, gas compositions, gas density, and flow rates. With the data and the aid of fundamental thermodynamic equations and MATLAB program codes, analysis was carried out on combustion to ascertain the amount of flue gases. Analyses revealed that a total of 1.99175 × 1011 standard cubic feet of gas was flared during the said period, generating anthropogenics estimated at 582,319,618.1825 m3 (≈1.046 Mt) of CO2, 1,077,510,054.31 m3 (≈2.0 Mt) of water vapour, 14,960,560.91 m3 of methane emitted and contaminated the atmosphere creating serious environmental concerns. Further analyses also showed that the approximate adiabatic flame temperature is about 1965&degC for the field under investigation. Exergy analyses carried out also revealed that a total of 3.6099 × 1013 kJ (36.099 TJ) of exergy was available which would have translated to 1.0189 × 1010 kWh of electrical energy for the period under investigation. Conclusively, some measures that can be taken to prevent gas flaring are that every new project on oil and gas should incorporate technical details of gas gathering and utilization plan at the conceptual and design phases of projects for gas commercialization, establishment of more gas-to-power project for gas utilization. Also Carbon capture technology should be enhanced, although the best option is flaring out based on the astronomical amount of carbon (IV) oxide and other greenhouse gases depicted by the results. The entire work and results showed that gas flaring is undesired and pernicious because it has thermal, environmental and economic consequences.

Экспериментальное определение параметров магнитного сердечника и катушки индуктивности на его основе

Introduction. The article is devoted to the description of an experimental method used to determine the magnetization curve of a core for calculating an inductor. It is convenient to be used in the absence of parameters of the core magnetic material or to refine the parameters of the finished coil. Materials and methods. It is proposed to generate a current pulse in a winding wound on the core to measure the magnetization curve – the dependence of the magnetic flux on the magnetomotive force Φ( F ). It is suggested to implement this with a thyristor-capacitor circuit. In this case, the magnetomotive force measurement is carried out with respect to the current in the winding; while the magnetic flux in the core is one of the ways: either by means of an additional flux measuring winding, or indirectly from the voltage on the main winding. Results. A MATLAB program code is suggested to process the results and plot the magnetization curves for the second method for the core of GM24DS ShL 40´80 (100´40) TU 1261-032-12287107-2010 of Gammamet firm with different gaps. Based on the resulting data, the coil parameters are calculated: inductance, magnetic conductivity, maximum magnetic flux and saturation the magnetomotive force. Based onthe resulting characteristics, the calculation of the coil for a given inductance and maximum current is suggested. Discussion. This technique is universal and can be used to determine the parameters of magnetic cores of different types, this calculation can be used to refine the parameters of the inductance coils on these cores. Conclusions. The result of the research is a family of magnetization characteristics Φ( F ) for the core GM24DS ShL 40´80 (100´40) TU 1261-032-12287107-2010 of Gammamet firm obtained and its maximum magnetic saturation flux Φ m determined. The data obtained is used to calculate the inductor based on the initial data.

Matlab Based Performance Evaluation of Natural Gas Transmission System due to Corrosion

Pipe corrosion is one of the serious issues associated with transportation of gases using old pipes. As a result of internal corrosion due to the accumulation of various corrosive materials, the performance of the transmission pipes is affected with ages. This paper aimed to evaluate the effect of the age of pipes on the performance of natural gas transmission pipeline network system. A simulation model was developed for looped pipeline configuration using MATLAB programming code. Newton Raphson method was used to determine the unknown pressure and flow parameters which are essential to evaluate the performance of the pipeline networks. The mathematical model was derived from the principles of fluid flow, mass conservation, and compressor characteristics. The pipe flow equations were modified to incorporate the effect of the age of pipes for evaluating the performance of the pipeline networks with respect to ages. Analyses performed on a looped pipeline network systems demonstrated that age has significant effect on the performance of the network. It was noted that the flow capacities reduced by 5.06 and 6.75% when the service life of the pipeline network reached 15 and 20 years, respectively. With the current rising price of natural gas, the reduction in flow capacity could result huge amount of cost for the nation operating large volume of gases. The results of the simulation model have been verified and validated using the techniques available in the area of pipeline network simulation.

Physical, mathematical, and numerical derivations of the Cahn–Hilliard equation

We review physical, mathematical, and numerical derivations of the binary Cahn–Hilliard equation (after John W. Cahn and John E. Hilliard). The phase separation is described by the equation whereby a binary mixture spontaneously separates into two domains rich in individual components. First, we describe the physical derivation from the basic thermodynamics. The free energy of the volume Ω of an isotropic system is given by NV∫Ω[F(c)+0.5∊2|∇c|2]dx, where NV, c, F(c), ∊, and ∇c represent the number of molecules per unit volume, composition, free energy per molecule of a homogenous system, gradient energy coefficient related to the interfacial energy, and composition gradient, respectively. We define the chemical potential as the variational derivative of the total energy, and its flux as the minus gradient of the potential. Using the usual continuity equation, we obtain the Cahn–Hilliard equation. Second, we outline the mathematical derivation of the Cahn–Hilliard equation. The approach originates from the free energy functional and its justification of the functional in the Hilbert space. After calculating the gradient, we obtain the Cahn–Hilliard equation as a gradient flow. Third, various aspects are introduced using numerical methods such as the finite difference, finite element, and spectral methods. We also provide a short MATLAB program code for the Cahn–Hilliard equation using a pseudospectral method.

Quantitative data analysis of ESAR data

Abstract. A synthetic aperture radar (SAR) data processing uses the backscattered electromagnetic wave to map radar reflectivity of the ground surface. The polarization property in radar remote sensing was used successfully in many applications, especially in target decomposition. This paper presents a case study to the experiments which are performed on ESAR L-Band full polarized data sets from German Aerospace Center (DLR) to demonstrate the potential of coherent target decomposition and the possibility of using the weather radar measurement parameter, such as the differential reflectivity and the linear depolarization ratio to obtain the quantitative information of the ground surface. The raw data of ESAR has been processed by the SAR simulator developed using MATLAB program code with Range-Doppler algorithm.