Inverse problems in the design, modeling and testing of engineering systems

Formulations, classification, areas of application, and approaches to solving different inverse problems are considered for the design of structures, modeling, and experimental data processing. Problems in the practical implementation of theoretical-experimental methods based on solving inverse problems are analyzed in order to identify mathematical models of physical processes, aid in input data preparation for design parameter optimization, help in design parameter optimization itself, and to model experiments, large-scale tests, and real tests of engineering systems

A Study of Anyon Statistics by Breit Hamiltonian Formalism

We study the anyon statistics of a $2 + 1$ dimensional Maxwell-Chern-Simons (MCS) gauge theory by using a systemmetic metheod, the Breit Hamiltonian formalism.Comment: 25 pages, LATE

Analysis of strained state of metal- and woodworkng tools as a result of plastic strain techniques

The article outlines the results of the research into the design of cutting tools composed of two metals with different properties. The research proves their applicability in various technological operations of metal and wood processing

Influence of TiN-coatings of hard alloy knives on exploitation of wood-cutting milling tool when processing laminated chipboard

The influence of TiN-coatings surface of cutters mill wood tools on wear of cutters for milling special woods was investigated. The TiN-coatings were formed on surfaces of import cutting inserts of mill tools by the method of condensation from a plasma phase in a vacuum with ion bombardment of surface. The element composition coatings and tools, the surface morphology of cutting tools were studied by X-ray microanalysis and transmission electron microscopy. The phase composition of import cutting tools is a hard alloy with type of WC-3. The tools consist of double-blade cutters with TiN coatings for milling special woods showed growth of wear resistance by 20% in comparison with bare tools. There is abrasive chemical type of wear on surface coating of cutters mill tools

Power Electronic design of a Multi MW dc/dc converter

• In this thesis, two topologies from a Zero voltage switching family are compared in terms of the power losses and weight of the magnetic components. These prerequisites are dictated by the purpose of the application - an offshore converter platform for an HVDC line. Two candidates were chosen: a Single active bridge dc/dc converter and a Dual active bridge dc/dc converter. The both topologies are implemented in Simulink at 2 different operating frequencies: 2 kHz and 10 kHz. The power rating of the application is 2.7 MW. The input and the output voltages are 3.6 kV and 40 kV respectively. Because of the fact that the specificity of the application does not imply a constant power supply the converters are tested in terms that they should remain in the lossless switching range even when the input power is reduced. • The both converters have very high efficiency. The simulations have shown, that the DAB topology does not have any switching losses at all, neither in the transistors nor in the diodes. The primary side of the SAB topology operates without any switching losses in the transistors as well, though pretty high reverse recovery losses were observed in the rectifying stage. The converters performed very well with the reduced power supply and remained in the soft-switching region far below the 40 % of the nominal supply

Explicit Sensitivity Coefficients for Estimation of Temperature-Dependent Thermophysical Properties in Inverse Transient Heat Conduction Problems

Explicit expressions are obtained for sensitivity coefficients to separately estimate temperature-dependent thermophysical properties, such as specific heat and thermal conductivity, in two-dimensional inverse transient heat conduction problems for bodies with irregular shape from temperature measurement readings of a single sensor inside the body. The proposed sensitivity analysis scheme allows for the computation of all sensitivity coefficients in only one direct problem solution at each iteration with no need to solve the sensitivity and adjoint problems. In this method, a boundary-fitted grid generation (elliptic) method is used to mesh the irregular shape of the heat conducting body. Explicit expressions are obtained to calculate the sensitivity coefficients efficiently and the conjugate gradient method as an iterative gradient-based optimization method is used to minimize the objective function and reach the solution. A test case with different initial guesses and sensor locations is presented to investigate the proposed inverse analysis

Inspiring the Next Generation: The International Space Station Education Accomplishments

The International Space Station (ISS) has a unique ability to capture the imagination of both students and teachers worldwide. Since 2000, the presence of humans onboard ISS has provided a foundation for numerous educational activities aimed at capturing that interest and motivating study in the sciences, technology, engineering and mathematics (STEM). Over 43 million students around the world have participated in ISS-related educational activities. Projects such as YouTube Space Lab, Sally Ride Earth Knowledge-based Acquired by Middle Schools (EarthKAM), SPHERES (Synchronized Position Hold Engage and Reorient Experimental Satellites) Zero-Robotics, Tomatosphere, and MAI-75 events among others have allowed for global student, teacher and public access to space through student classroom investigations and real-time audio and video contacts with crewmembers. Educational activities are not limited to STEM but encompass all aspects of the human condition. This is well illustrated in the Uchu Renshi project, a chain poem initiated by an astronaut while in space and continued and completed by people on Earth. With ISS operations now extended to 2024, projects like these and their accompanying educational materials are available to more students around the world. From very early on in the program's history, students have been provided with a unique opportunity to get involved and participate in science and engineering projects. Many of these projects support inquiry-based learning that allows students to ask questions, develop hypothesis-derived experiments, obtain supporting evidence and identify solutions or explanations. This approach to learning is well-published as one of the most effective ways to inspire students to pursue careers in scientific and technology fields. Ever since the first space station element was launched, a wide range of student experiments and educational activities have been performed, both individually and collaboratively, by all the international partner agencies, National Aeronautics and Space Administration (NASA), Canadian Space Agency (CSA), European Space Agency, (ESA), Japan Aerospace Exploration Agency (JAXA) and Russian Federal Space Agency (Roscosmos), and a number of non-participating countries, some under commercial agreements. Many of these programs still continue, and others are being developed and added to the stations tasks on a regular basis. These diverse student experiments and programs fall into one of the following categories: student-developed experiments; students performing classroom versions of ISS experiments; students participating in ISS investigator experiments; education competitions; students participating in ISS Engineering Education; Education Demonstrations and Cultural Activities. This paper summarizes some of the main student experiments and educational activities that have been conducted on the space station

Modeling of radiative - conductive heat transfer in compositing materials

A layer of composite material is investigated, which is heated one-sidedly with one-dimensional energy transfer accounting for thermal conductivity and radiation. A mathematical model is suggested for non-stationary coefficient thermophysical problem under radiative-conductive heat transfer in a material layer. Temperature dependencies of thermal capacity and thermal conductivity coefficient of composite radio-transparent material have been determined through numerical modeling by solving the coefficient reverse problem of thermal conductivity

Function Estimation in Inverse Heat Transfer Problems Based on Parameter Estimation Approach

A new sensitivity analysis scheme is presented based on explicit expressions for sensitivity coefficients to estimate timewise varying heat flux in heat conduction problems over irregular geometries using the transient readings of a single sensor. There is no prior information available on the functional form of the unknown heat flux; hence, the inverse problem is regarded as a function estimation problem and sensitivity and adjoint problems are involved in the solution of the inverse problem to recover the unknown heat flux. However, using the proposed sensitivity analysis scheme, one can compute all sensitivity coefficients explicitly in only one direct problem solution at each iteration without the need for solving the sensitivity and adjoint problems. In other words, the functional form of the unknown heat flux can be numerically estimated by using the parameter estimation approach. In this method, the irregular shape of heat-conducting body is meshed using the boundary-fitted grid generation (elliptic) method. Explicit expressions are given to compute the sensitivity coefficients efficiently and the steepest-descent method is used as the minimization method to minimize the objective function and reach the solution. Three test cases are presented to confirm the accuracy and efficiency of the proposed inverse analysis

Parametric identification of mathematical models of coupled conductive-radiative heat transfer

In many practical situations it is impossible to measure directly such characteristics of analyzed materials as thermal and radiation properties. The only way, which can often be used to overcome these difficulties, is indirect measurements. This type of measurements is usually formulated as the solution of inverse heat transfer problems. Such problems are illposed in mathematical sense and their main feature shows itself in the solution instabilities. That is why special regularizing methods are needed to solve them. The experimental methods of identification of the mathematical models of heat transfer based on solving of the inverse problems are one of the modern effective solving manners. The goal of this paper is to estimate thermal and radiation properties of advanced materials using the approach based on inverse methods (as example: thermal conductivityλ(T) , heat capacity C(T) and emissivity ε (T )). New metrology under development is the combination of accurate enough measurements of thermal quantities, which can be experimentally observable under real conditions and accurate data processing, which are based on the solutions of inverse heat transfer problems. In this paper, the development of methods for estimating thermal and radiation characteristics is carried out for thermally stable high temperature materials. Such problems are of great practical importance in the study of properties of materials used as non-destructive surface coating in objects of space engineering, power engineering etc. Also the corresponded optimal experiment design problem is considered. The algorithm is based on the theory of Fisher information matrix