Numerical Values Of Temperature Research Articles

Radiometric Infrared Thermography of Solar Photovoltaic Systems: An Explainable Predictive Maintenance Approach for Remote Aerial Diagnostic Monitoring

Solar photovoltaic (SPV) arrays are crucial components of clean and sustainable energy infrastructure. However, SPV panels are susceptible to thermal degradation defects that can impact their performance, thereby necessitating timely and accurate fault detection to maintain optimal energy generation. The considered case study focuses on an intelligent fault detection and diagnosis (IFDD) system for the analysis of radiometric infrared thermography (IRT) of SPV arrays in a predictive maintenance setting, enabling remote inspection and diagnostic monitoring of the SPV power plant sites. The proposed IFDD system employs a custom-developed deep learning approach which relies on convolutional neural networks for effective multiclass classification of defect types. The diagnosis of SPV panels is a challenging task for issues such as IRT data scarcity, defect-patterns’ complexity, and low thermal image acquisition quality due to noise and calibration issues. Hence, this research carefully prepares a customized high-quality but severely imbalanced six-class thermographic radiometric dataset of SPV panels. With respect to previous approaches, numerical temperature values in floating-point are used to train and validate the predictive models. The trained models display high accuracy for efficient thermal anomaly diagnosis. Finally, to create a trust in the IFDD system, the process underlying the classification model is investigated with perceptive explainability, for portraying the most discriminant image features, and mathematical-structure-based interpretability, to achieve multiclass feature clustering.

МАТЕМАТИЧНІ МОДЕЛІ ВИЗНАЧЕННЯ ТЕМПЕРАТУРНИХ ПОЛІВ У НЕОДНОРІДНИХ ЕЛЕМЕНТАХ ЦИФРОВИХ ПРИСТРОЇВ ІЗ УРАХУВАННЯМ ТЕРМОЧУТЛИВОСТІ Primary tabs View(active tab) Edit Translate

Linear and nonlinear mathematical models for determining the temperature field and subsequently analyzing temperature regimes in isotropic spatial media with semi-through foreign inclusions subjected to internal and external thermal loads are developed. For this purpose, the heat transfer coefficient for such structures is described as a single unit using asymmetric unit functions, which makes it possible to consider boundary value problems of heat transfer with one linear and nonlinear differential equations of heat transfer with discontinuous and singular coefficients and linear and nonlinear boundary conditions on the boundary surfaces of the media. In the case of a nonlinear boundary value problem, the introduced linearizing function is used to linearize the original nonlinear heat conduction equation and nonlinear boundary conditions, and as a result, a partially linearized second-order differential equation with partial derivatives and discontinuous and singular coefficients is obtained relative to the linearizing function with partially linearized boundary conditions. For the final linearization of the partially linearized differential equation and boundary conditions, the temperature is approximated by one of the spatial coordinates on the boundary surfaces of the inclusion by piecewise linear functions, as a result of which both the differential equation and boundary conditions become fully linearized. To solve the resulting linear boundary value problem, the Hankel integral transformation method is used, which results in an analytical solution that determines the introduced linearizing function. As an example, the linear dependence of the thermal conductivity coefficient of structural materials of a structure on temperature, which is often used in many practical problems, is chosen. As a result, analytical relations in the form of quadratic equations were obtained to determine the temperature distribution in a thermally sensitive layer with a foreign semi-through inclusion under external heating in the form of a heat flux. A numerical analysis of the temperature behavior as a function of spatial coordinates for given values of geometric and thermophysical parameters is performed. The influence of a foreign inclusion on the temperature distribution is investigated if the VK94-I ceramic is chosen as the material of the medium and the inclusion is silver. To determine the numerical values of temperature in the above structures, as well as to analyze heat transfer processes inside these structures caused by internal and external thermal loads, software tools have been developed that have been used to perform a geometric image of the temperature distribution depending on spatial coordinates. The obtained numerical temperature values indicate that the developed mathematical models for analyzing heat transfer processes in spatially heterogeneous environments with internal and external heating correspond to a real physical process. The software also makes it possible to analyze such environments subjected to internal and external thermal loads in terms of their thermal resistance. As a result, it becomes possible to increase it and protect it from overheating, which can cause the destruction of not only individual elements but also the entire structure.

Fractional Order Transient Thermoelastic Stress Analysis of a Thin Circular Sector Disk

Analysis of transient thermoelastic stress distribution of a thin circular sector disk with a time-fractional derivative of order α is proposed. The Neumann types of boundary conditions are used and the integral transform method and Caputo fractional derivative are used to obtain the analytical solutions of the temperature, displacement, and stresses. Numerical values of temperature, displacement, and stresses are computed for an Aluminum (pure) material and presented graphically with help of Mathcad software.

МАТЕМАТИЧНІ ПРОСТОРОВІ МОДЕЛІ ВИЗНАЧЕННЯ ТЕМПЕРАТУРНОГО ПОЛЯ ІЗ ЛОКАЛЬНО ЗОСЕРЕДЖЕНИМ ТЕПЛОВИМ НАГРІВАННЯМ

Linear and nonlinear mathematical models for determining the temperature field, and later the analysis of temperature regimes in isotropic spatial inhomogeneous media exposed to internal and external thermal loads have been developed. To do this, the thermal conductivity for such structures is described as a whole using symmetric unit functions, which allows us to consider boundary thermal conductivity problems with one linear and nonlinear differential equation of thermal conductivity with discontinuous coefficients and linear and nonlinear boundary conditions on boundary surfaces. In the case of a nonlinear boundary value problem, the Kirchhoff transform is applied, which linearizes the initial nonlinear equation of thermal conductivity and nonlinear boundary conditions and results in a second-order linear differential equation with partial derivatives and singular coefficients with respect to the Kirchhoff function with linear conditions. To solve the obtained linear boundary value problem, the method of integral Fourier transform was used, as a result of which an analytical solution was obtained, which determines the Kirchhoff linearizing function. As an example, the linear and cubic dependences of the thermal conductivity of structural materials on the structure, which are often used in many practical problems, are chosen. As a result, analytical relations in the form of quadratic and biquadratic equations are obtained to determine the temperature distribution in the thermosensitive layer with foreign inclusion at external local heating. Numerical analysis of temperature behavior as a function of spatial coordinates for given values of geometric and thermophysical parameters is performed. The influence of foreign inclusion on the temperature distribution was studied if the material of the medium was selected ceramics VK94-I, and the inclusion – silver, aluminum and silicon. To determine the numerical values of temperature in these structures, as well as the analysis of heat transfer processes in the middle of these structures due to internal and external heat loads, developed software that uses a geometric representation of temperature distribution depending on spatial coordinates. The obtained numerical values of temperature testify to the correspondence of the developed mathematical models of the analysis of heat exchange processes in spatial inhomogeneous media with internal and external heating to the real physical process. Software also allows you to analyze this type of environment, which are exposed to internal and external heat loads, in terms of their heat resistance. As a result, it becomes possible to increase it and protect it from overheating, which can lead to the destruction of not only individual elements but also the entire structure.

Математичні моделі температурного поля в термочутливих елементах електронних пристроїв

Nonlinear mathematical models for the analysis of temperature regimes in a thermosensitive isotropic plate heated by locally concentrated heat sources have been developed. For this purpose, the heat-active zones of the plate are described using the theory of generalized functions. Given this equation of thermal conductivity and boundary conditions contain discontinuous and singular right parts. The original nonlinear equations of thermal conductivity and nonlinear boundary conditions are linearized by Kirchhoff transformation. To solve the obtained boundary value problems, the integral Fourier transform was used and, as a result, their analytical solutions in the images were determined. The inverse integral Fourier transform was applied to these solutions, which made it possible to obtain analytical expressions for determining the Kirchhoff variable. As an example, the linear dependence of the thermal conductivity on temperature is chosen, which is often used in many practical problems. As a result, analytical relations were obtained to determine the temperature in the heat-sensitive plate. The given analytical solutions are presented in the form of improper convergent integrals. According to Newton’s method (three eighths), numerical values of these integrals are obtained with a certain accuracy for given values of plate thickness, spatial coordinates, specific power of heat sources, thermal conductivity of structural materials of the plate and geometric parameters of the heat-active zone. The material of the plate is silicon and germanium. To determine the numerical values of temperature in the structure, as well as the analysis of heat transfer processes in the middle of the plate due to local heating, developed software, using which geometric mapping of temperature distribution depending on spatial coordinates, thermal conductivity, specific heat flux density. The obtained numerical values of temperature testify to the correspondence of the developed mathematical models of the analysis of heat exchange processes in the thermosensitive plate with local heating to the real physical process.

Температурні режими в термочутливих елементах цифрових пристроїв, спричинені локальним нагріванням

Nonlinear mathematical models for the analysis of temperature regimes in a thermosensitive isotropic plate heated by locally concentrated heat sources have been developed. For this purpose, the heat-active zones of the plate are described using the theory of generalized functions. Given this, the equation of thermal conductivity and boundary conditions contain discontinuous and singular right parts. The original nonlinear equations of thermal conductivity and nonlinear boundary conditions are linearized by Kirchhoff transformation. To solve the obtained boundary value problems, the integral Fourier transform was used and, as a result, their analytical solutions in the images were determined. The inverse integral Fourier transform was applied to these solutions, which made it possible to obtain analytical expressions for determining the Kirchhoff variable. As an example, the linear dependence of the thermal conductivity on temperature is chosen, which is often used in many practical problems. As a result, analytical relations were obtained to determine the temperature in the heat-sensitive plate. The given analytical solutions are presented in the form of improper convergent integrals. According to Newtons method (three-eighths), numerical values of these integrals are obtained with a certain accuracy for given values of plate thickness, spatial coordinates, specific power of heat sources, the thermal conductivity of structural materials of the plate, and geometric parameters of the heat-active zone. The material of the plate is silicon and germanium. To determine the numerical values of temperature in the structure, as well as the analysis of heat transfer processes in the middle of the plate due to local heating, developed software, using which geometric mapping of temperature distribution depending on spatial coordinates, thermal conductivity, specific heat flux density. The obtained numerical values of temperature testify to the correspondence of the developed mathematical models of the analysis of heat exchange processes in the thermosensitive plate with local heating to the real physical process. The software also makes it possible to analyze such environments that are exposed to local heat loads in terms of their heat resistance. As a result, it becomes possible to increase it and to protect it from overheating, which can cause the destruction not only of individual elements but also of the entire structure. Keywords: temperature field; isotropic thermosensitive plate; thermal conductivity; heat-insulated surface; perfect thermal contact; local heating.

Математична модель теплообміну в елементах цифрових технологічних пристроїв

A mathematical model of heat exchange analysis between an isotropic two-layer plate heated by a point heat source concentrated on the conjugation surfaces of layers and the environment has been developed. To do this, using the theory of generalized functions, the coefficient of thermal conductivity of the materials of the plate layers is shown as a whole for the whole system. Given this, instead of two equations of thermal conductivity for each of the plate layers and the conditions of ideal thermal contact, one equation of thermal conductivity in generalized derivatives with singular coefficients is obtained between them. To solve the boundary value problem of thermal conductivity containing this equation and boundary conditions on the boundary surfaces of the plate, the integral Fourier transform was used and as a result an analytical solution of the problem in images was obtained. An inverse integral Fourier transform was applied to this solution, which made it possible to obtain the final analytical solution of the original problem. The obtained analytical solution is presented in the form of an improper convergent integral. According to Simpson's method, numerical values of this integral are obtained with a certain accuracy for given values of layer thickness, spatial coordinates, specific power of a point heat source, thermal conductivity of structural materials of the plate and heat transfer coefficient from the boundary surfaces of the plate. The material of the first layer of the plate is copper, and the second is aluminum. Computational programs have been developed to determine the numerical values of temperature in the given structure, as well as to analyze the heat exchange between the plate and the environment due to different temperature regimes due to heating the plate by a point heat source concentrated on the conjugation surfaces. Using these programs, graphs are shown that show the behavior of curves constructed using numerical values of the temperature distribution depending on the spatial coordinates. The obtained numerical values of temperature indicate the correspondence of the developed mathematical model of heat exchange analysis between a two-layer plate with a point heat source focused on the conjugation surfaces of the layersand the environment, the real physical process.

Parents\u2019 concerns and beliefs about temperature measurement in children: a qualitative study

BackgroundNearly 40% of parents with children aged 6 to 17 months consult a healthcare professional when their child has a high temperature. Clinical guidelines recommend temperature measurement in these children, but little is known about parents’ experiences of and beliefs about temperature measurement. This study aimed to explore parents’ concerns and beliefs about temperature measurement in children.MethodsSemi-structured qualitative interviews were conducted from May 2017 to June 2018 with 21 parents of children aged 4 months to 5.5 years, who were purposively sampled from the METRIC study (a method comparison study comparing non-contact infrared thermometers to axillary and tympanic thermometers in acutely ill children). Data analysis followed a thematic approach.ResultsParents described the importance of being able to detect fever, in particular high fevers, and how this then influenced their actions. The concept of “accuracy” was valued by parents but the aspects of performance which were felt to reflect accuracy varied. Parents used numerical values of temperature in four main ways: determining precision of the thermometer on repeat measures, detecting a “bad” fever, as an indication to administer antipyretics, or monitoring response to treatment. Family and social networks, the internet, and medical professionals and resources, were all key sources of advice for parents regarding fever, and guiding thermometer choice.ConclusionsTemperature measurement in children has diagnostic value but can either empower, or cause anxiety and practical challenges for parents. This represents an opportunity for both improved communication between parents and healthcare professionals, and technological development, to support parents to manage febrile illness with greater confidence in the home.

МАТЕМАТИЧНА МОДЕЛЬ ТЕПЛООБМІНУ В ЕЛЕМЕНТАХ ЦИФРОВИХ ПРИСТРОЇВ

A mathematical model of heat exchange analysis between an isotropic two-layer plate heated ba point heat source concentrated on the conjugation surfaces of layers and the environment has been developed. To do this, using the theory of generalized functions, the coefficient of thermal conductivity of the materials of the plate layers is shown as a whole for the wholesystem.Given this, instead of two equations of thermal conductivity for each of the plate layers and the conditions of ideal thermal contact, one equation of thermal conductivity ingeneralized derivatives with singular coefficients is obtained between them. To solve the boundary value problem of thermal conductivity containing this equation and boundary conditions on the boundary surfaces of the plate, the integral Fourier transform was used and as a result an analytical solution of the problem in images was obtained. An inverse integral Fourier transform was applied to this solution, which made it possible to obtain the final analytical solution of the original problem. The obtained analytical solution is presented in the form of an improper convergent integral. According to Simpsons method, numerical values of this integral are obtained with a certain accuracy for given values of layer thickness, spatial coordinates, specific power of a point heat source, thermal conductivity of structural materials of the plate and heat transfer coefficient from the boundary surfaces of the plate. The material of the first layer of the plate is copper, and the second is aluminum. Computational programs have been developed to determine the numerical values of temperature in the given structure, as well as to analyze the heat exchange between the plate and the environment due to different temperature regimes due to heating the plate by a point heat source concentrated on the conjugation surfaces. Using these programs, graphs are shown that show the behavior of curves constructed using numerical values of the temperature distribution depending on the spatial coordinates. The obtained numerical values of temperature indicate the correspondence of the developed mathematical model of heat exchange analysis between a two-layer plate with a point heatsource focused on the conjugation surfaces of the layersand the environment, the real physical process.

Математичні моделі визначення температурних режимів у елементах літій-іонних акумуляторних батарей

Удосконалено раніше розроблені та наведено нові математичні моделі визначення та аналізу температурних режимів в окремих елементах літій-іонних акумуляторних батарей, які геометрично описано ізотропними півпростором і простором із внутрішнім джерелом тепла циліндричної форми. Також розглянуто випадки для півпростору, коли тепловиділяючий циліндр є тонким, а для простору, коли він є термочутливим. Для цього з використанням теорії узагальнених функцій у зручній формі записано вихідні диференціальні рівняння теплопровідності з крайовими умовами. Для розв'язування отриманих крайових задач теплопровідності використано інтегральне перетворення Ганкеля і внаслідок отримано аналітичні розв'язки в зображеннях. До цих розв'язків застосовано обернене інтегральне перетворення Ганкеля, яке дало змогу отримати остаточні аналітичні розв'язки вихідних задач. Отримані аналітичні розв'язки подано у вигляді невласних збіжних інтегралів. Для визначення числових значень температури в наведених конструкціях, а також аналізу теплообміну в елементах літій-іонних батарей, зумовленого різними температурними режимами завдяки нагріванню внутрішніми джерелами тепла, зосередженими в об'ємі циліндра, розроблено обчислювальні програми. Із використанням цих програм наведено графіки, які відображають поведінку кривих, побудованих із використанням числових значень розподілу температури залежно від просторових радіальної та аксіальної координат. Отримані числові значення температури свідчать про відповідність наведених математичних моделей визначення розподілу температури реальному фізичному процесу. Програмні засоби також дають змогу аналізувати середовища із внутрішнім нагріванням, зосередженим у просторових фігурах правильної геометричної форми, щодо їх термостійкості. Як наслідок, стає можливим її підвищити, визначити допустимі температури нормальної роботи літій-іонних батарей, захистити їх від перегрівання, яке може спричинити руйнування не тільки окремих елементів, а й всієї конструкції.

Numerical investigation on effects of fuel tube diameter and co-flow velocity in a methane/air non-premixed flame

In this paper, the effects of variations in the fuel tube diameter and co-flow velocity in the combustion chamber on the non-premixed laminar flame are investigated. Methane gas, as a fuel, and the dry air, as an oxidizer. The size of the combustion chamber is constant and, by changing the fuel tube diameter and co-flow velocity, changes in the numerical values of temperature, velocity, density, and concentration of the species of reactants and products in the combustion chamber are evaluated. A finite volume method (FVM) with staggered grids is used for numerical solution. Equations of continuity, momentum, energy, ideal gas state and kinetic equations with thermodynamic and thermochemical information of chemical species are solved using numerical method of SIMPLE. The convective terms are discretized using Power Law scheme (PLS).The calculations are carried out using Dryer and Glassman’s three-stage chemical kinetics. Variable under relaxation factor dependent on temperature has been used to handle the solving chemical kinetic equations. Initially, the results of calculations are compared with the experimental and numerical results of other researchers, which show an acceptable agreement.. The results show that increasing the diameter ratio reduces the length of the flame. With the large ratio of the diameters, location of the combustion’s maximum temperature is at the chamber entrance and for the small diameter ratios, its location moves to nearly outlet of the chamber. In addition, the reduction of the ratio of the diameters increases the flame lift-off. Also the results show that the optimal of diameters ratio is 0.6 in order to prevent the lift-off flame and return the flame to inlet opening of combustion chamber. Also increasing the fuel tube diameter, increases the amount of oxygen due to the return flow formation and decreases the volumes of water vapor and carbon dioxide in the centerline of the combustion chamber. The flame length attains the maximum possible value with respect to diameter ratio of 0.6 at inlet air velocity of 0.3 m/s. In addition, it is shown that increasing the air velocity increases the total flame lift-off and flame length until the air velocity reaches the value of around 0.3 m/s and by increasing the air velocity more than 0.3 m/s, the total flame lift-off and flame length decreases.

МАТЕМАТИЧНІ МОДЕЛІ ТЕПЛООБМІНУ В ЕЛЕМЕНТАХ ТУРБОГЕНЕРАТОРІВ (ПРОДОВЖЕННЯ)

Previously developed [8] and presented new mathematical models for the analysis of temperature regimes in individual elements of turbo generators, which are geometrically described by isotropic half-space and space with an internal heat source of cylindrical shape. Cases are also considered for half-space, when the fuel-releasing cylinder is thin, and for space, when it is heat-sensitive. For this purpose, using the theory of generalized functions, the initial differential equations of thermal conductivity with boundary conditions are written in a convenient form. To solve the obtained boundary value problems of thermal conductivity, the integral Hankel transformation was used, and as a result, analytical solutions in the images were obtained. The inverse Hankel integral transformation was applied to these solutions, which made it possible to obtain the final analytical solutions of the initial problems. The obtained analytical solutions are presented in the form of improper convergent integrals. Computational programs have been developed to determine the numerical values ​​of temperature in the above structures, as well as to analyze the heat transfer in the elements of turbo generators due to different temperature regimes due to heating by internal heat sources concentrated in the cylinder volume. Using these programs, graphs are presented that show the behavior of curves constructed using numerical values ​​of the temperature distribution depending on the spatial radial and axial coordinates. The obtained numerical values ​​of temperature indicate the correspondence of the given mathematical models for determining the temperature distribution to the real physical process. The software also allows you to analyze media with internal heating, concentrated in the spatial figures of the correct geometric shape, in terms of their heat resistance. As a result, it becomes possible to increase it, to determine the allowable temperatures of normal operation of turbo generators, to protect them from overheating, which can cause the destruction of not only individual elements but also the entire structure.

Thermal 3D model for non-homogeneous elements in mobile devices

A mathematical model for the analysis of heat exchange between the environment and an isotropic space layer with an alien inclusions is developed, which is heated by a heat flux centered on one of the boundary surfaces. For this purpose, using the theory of generalized functions, the coefficient of thermal conductivity of this structure is depicted as one unit for the whole system. In view of this, instead of two equations of thermal conductivity for the layer and the inclusion and conditions of perfect thermal contact on the surfaces of the junction between them, one equation of thermal conductivity was obtained in the generalized derivatives with breaking coefficients. We consider the case when the inclusion sizes are small compared to the distances from the inclusion surfaces to the boundary surfaces of the layer. In this connection, the combined thermophysical parameters were introduced and the thermal coefficients of the thermal conductivity equation were transformed into singular ones. For the solution of the boundary value problem of thermal conductivity containing this equation and boundary conditions on the boundary surfaces of the layer, an integral Fourier transform was used and, as a result, an analytical solution of the problem in the images was obtained. The inverse integral Fourier transform was applied to this solution, which made it possible to obtain the final analytical solution of the original problem. The analytical solution obtained is presented as a non-native double convergent integral. To determine the numerical values ​​of the temperature in the above design, as well as to analyze the heat exchange between the layer and the environment caused by different temperature regimes due to the heating of the inhomogeneous layer by a heat source concentrated in the area of ​​inclusion, computational programs have been developed. Using these programs, graphs are displayed showing the behavior of curves constructed using numerical values ​​of the temperature distribution depending on the spatial coordinates for different inclusion materials. The obtained numerical values ​​of temperature indicate a significant influence of the inclusion on its distribution in the design "layer-inclusion". The software also makes it possible to analyze these inhomogeneous media with respect to their heat resistance during heating. As a consequence, it becomes possible to raise and protect it from overheating, which can cause destruction not only of individual elements, but also of the whole structure.

Winding Hottest-Spot Temperature Analysis in Dry-Type Transformer Using Numerical Simulation

A thermal analysis of a 5 kVA dry-type transformer under linear and non-linear loads conditions is studied in this paper. The main goal here is to calculate the hottest-spot transformer temperature under free convection through the resolution of the heat conduction equation in three dimensions (3D) using COMSOL Multiphysics®. The proposed technique was validated through experimental data obtained in laboratory. The temperature inside the cores was measured under the influence of free convection. The radiation emission was also measured through a thermal camera. The heat transfer coefficient for both conditions was obtained from empirical correlations. The hottest-spot temperatures were determined from the analysis in the commercial software which was used for the numerical simulations of the transformer heating and cooling under some loading conditions. The temperature residuals, that is, the experimental temperature values subtracted by the numerical temperature values, were below 10%. The numerical analysis found that the hottest-spot temperatures in the core reached 20 °C above the transformer insulation limit. The location of the hottest-spot as well as the obtained temperatures can be used to improve more resistant dry-type transformers.

Analysis of dissipated energy and temperature fields at severe notches of AISI 304L stainless steel specimens

In the last years, a large amount of fatigue test results from plain and bluntly notched specimens made of AISI 304L stainless steel were synthetized in a single scatter band by adopting the specific heat loss per cycle (Q) as a damage parameter. During a fatigue test, the Q parameter can be evaluated measuring the cooling gradient at a point of the specimens after having suddenly stopped the fatigue test. This measurement can be done by using thermocouples; however, due to the high stress concentration at the tip of severely notched components analysed in the present paper, an infrared camera achieving a much improved spatial resolution was adopted. A data processing technique is presented to investigate the heat energy distribution close to the notch tip of hot-rolled AISI 304L stainless steel specimens, having notch tip radii equal to 3, 1 and 0.5 mm and subjected to constant amplitude cyclic loads. A thermal finite element analysis was also performed by assigning heat generation in the appropriate region close to the notch tip. Then the numerical temperature values were compared with the experimental measurement.

Analytical, Numerical and Experimental Study of a Horizontal Electrothermal MEMS Microgripper for the Deformability Characterisation of Human Red Blood Cells.

Microgrippers are typical microelectromechanical systems (MEMS) that are widely used for micromanipulation and microassembly in both biological and micromanufacturing fields. This paper presents the design, modelling, fabrication and experimental testing of an electrothermal microgripper based on a ‘hot and cold arm’ actuator design that is suitable for the deformability characterisation of human red blood cells (RBCs). The analysis of the mechanical properties of human RBCs is of great interest in the field of medicine as pathological alterations in the deformability characteristics of RBCs have been linked to a number of diseases. The study of the microgripper’s steady-state performance is initially carried out by the development of a lumped analytical model, followed by a numerical model established in CoventorWare® (Coventor, Inc., Cary, NC, USA) using multiphysics finite element analysis. Both analytical and numerical models are based on an electothermomechanical analysis, and take into account the internal heat generation due to the applied potential, as well as conduction heat losses through both the anchor pads and the air gap to the substrate. The models are used to investigate key factors of the actuator’s performance including temperature distribution, deflection and stresses based on an elastic analysis of structures. Results show that analytical and numerical values for temperature and deflection are in good agreement. The analytical and computational models are then validated experimentally using a polysilicon microgripper fabricated by the standard surface micromachining process, PolyMUMPs™ (Durham, NC, USA). The microgripper’s actuation is characterised at atmospheric pressure by optical microscopy studies. Experimental results for the deflection of the microgripper arm tips are found to be in good agreement with the analytical and numerical results, with process-induced variations and the non-linear temperature dependence of the material properties accounting for the slight discrepancies observed. The microgripper is shown to actuate to a maximum opening displacement of 9 m at an applied voltage of 3 V, thus being in line with the design requirement of an approximate opening of 8 m for securing and characterising a RBC.

CFD modelling of air temperature distribution inside tunnel greenhouse in semi-arid region

In the semi-arid region of the southern Mediterranean especially the middle east of Tunisia, one of the main problems of climates is the large diurnal amplitude of temperature, with too low temperature during winter nights and too height temperature during summer day for successful plant growth and development the control of greenhouse environmental parameters is very important. In this work, a computational fluid dynamic software (CFX15.0) was used to study the micro-climate in a 6 × 8 m2 plastic tunnel. The validity of the computational fluid dynamics (CFD) model was investigated by comparing these results with experimental data collected on strategic days during a period of two months from 1 April to 5 May, 2016. The experiments were conducted in naturally ventilated for two different cases; in close and opening tunnel greenhouse. A very good agreement between experimental and numerical temperature values was verified.

CFD modelling of air temperature distribution inside tunnel greenhouse in semi-arid region

In the semi-arid region of the southern Mediterranean especially the middle east of Tunisia, one of the main problems of climates is the large diurnal amplitude of temperature, with too low temperature during winter nights and too height temperature during summer day for successful plant growth and development the control of greenhouse environmental parameters is very important. In this work, a computational fluid dynamic software (CFX15.0) was used to study the micro-climate in a 6 × 8 m2 plastic tunnel. The validity of the computational fluid dynamics (CFD) model was investigated by comparing these results with experimental data collected on strategic days during a period of two months from 1 April to 5 May, 2016. The experiments were conducted in naturally ventilated for two different cases; in close and opening tunnel greenhouse. A very good agreement between experimental and numerical temperature values was verified.

Localization of focused-ultrasound beams in a tissue phantom, using remote thermocouple arrays.

In focused-ultrasound procedures such as vessel cauterization or clot lysis, targeting accuracy is critical. To investigate the targeting accuracy of the focused-ultrasound systems, tissue phantoms embedded with thermocouples can be employed. This paper describes a method that utilizes an array of thermocouples to localize the focused ultrasound beam. All of the thermocouples are located away from the beam, so that thermocouple artifacts and sensor interference are minimized. Beam propagation and temperature rise in the phantom are simulated numerically, and an optimization routine calculates the beam location that produces the best agreement between the numerical temperature values and those measured with thermocouples. The accuracy of the method was examined as a function of the array characteristics, including the number of thermocouples in the array and their orientation. For exposures with a 3.3-MHz source, the remote-thermocouple technique was able to predict the focal position to within 0.06 mm. Once the focal location is determined using the localization method, temperatures at desired locations (including the focus) can be estimated from remote thermocouple measurements by curve fitting an analytical solution to the heat equation. Temperature increases in the focal plane were predicted to within 5% agreement with measured values using this method.

Computational Fluid Dynamics Analysis of Greenhouses with Artificial Heat Tube

With the workmanship decrease in farms, the necessity to rationalize the use of other inputs and the development of technology has rapidly expanded the use of computer simulation in agricultural systems. One of the agricultural systems in which the modeling process of plant growth has been more engaged is the greenhouse production for horticultural crops. In Mediterranean climate, it is during the night that the energy losses are important and can be compensated with an artificial heat input. In this work an experiment was performed in a greenhouse in the north of Portugal. Temperature values in several points and air velocity in the aperture were measured during the night for three different cases: natural convective heating (case A); artificial heating tubes (AHT) (case B); AHT and natural ventilation (case C). A CFD simulation, carried out using FLOTRAN module of ANSYS, was also performed in two-dimensional configuration to obtain the indoor air temperature and velocity fields for the three cases. A very good agreement between experimental and numerical temperature values were verified, which allows to validate the adopted numerical procedure. In case A, the average temperature was 2.2℃. An average increase of 6.7℃ and 3.5℃ on the air temperature was obtained for the case B and case C, respectively. These results clearly emphasis the influence of each thermal load on greenhouse indoor air properties.