Numerical Computation, Data Analysis and Software in Mathematics and Engineering

The present book contains 14 articles that were accepted for publication in the Special Issue “Numerical Computation, Data Analysis and Software in Mathematics and Engineering” of the MDPI journal Mathematics. The topics of these articles include the aspects of the meshless method, numerical simulation, mathematical models, deep learning and data analysis. Meshless methods, such as the improved element-free Galerkin method, the dimension-splitting, interpolating, moving, least-squares method, the dimension-splitting, generalized, interpolating, element-free Galerkin method and the improved interpolating, complex variable, element-free Galerkin method, are presented. Some complicated problems, such as tge cold roll-forming process, ceramsite compound insulation block, crack propagation and heavy-haul railway tunnel with defects, are numerically analyzed. Mathematical models, such as the lattice hydrodynamic model, extended car-following model and smart helmet-based PLS-BPNN error compensation model, are proposed. The use of the deep learning approach to predict the mechanical properties of single-network hydrogel is presented, and data analysis for land leasing is discussed. This book will be interesting and useful for those working in the meshless method, numerical simulation, mathematical model, deep learning and data analysis fields

High-Performance Integrated Window and Façade Solutions for California

The researchers developed a new generation of high-performance façade systems and supporting design and management tools to support industry in meeting California’s greenhouse gas reduction targets, reduce energy consumption, and enable an adaptable response to minimize real-time demands on the electricity grid. The project resulted in five outcomes: (1) The research team developed an R-5, 1-inch thick, triplepane, insulating glass unit with a novel low-conductance aluminum frame. This technology can help significantly reduce residential cooling and heating loads, particularly during the evening. (2) The team developed a prototype of a windowintegrated local ventilation and energy recovery device that provides clean, dry fresh air through the façade with minimal energy requirements. (3) A daylight-redirecting louver system was prototyped to redirect sunlight 15–40 feet from the window. Simulations estimated that lighting energy use could be reduced by 35–54 percent without glare. (4) A control system incorporating physics-based equations and a mathematical solver was prototyped and field tested to demonstrate feasibility. Simulations estimated that total electricity costs could be reduced by 9-28 percent on sunny summer days through adaptive control of operable shading and daylighting components and the thermostat compared to state-of-the-art automatic façade controls in commercial building perimeter zones. (5) Supporting models and tools needed by industry for technology R&D and market transformation activities were validated. Attaining California’s clean energy goals require making a fundamental shift from today’s ad-hoc assemblages of static components to turnkey, intelligent, responsive, integrated building façade systems. These systems offered significant reductions in energy use, peak demand, and operating cost in California

Machine Learning based Early Fault Diagnosis of Induction Motor for Electric Vehicle Application

Electrified vehicular industry is growing at a rapid pace with a global increase in production of electric vehicles (EVs) along with several new automotive cars companies coming to compete with the big car industries. The technology of EV has evolved rapidly in the last decade. But still the looming fear of low driving range, inability to charge rapidly like filling up gasoline for a conventional gas car, and lack of enough EV charging stations are just a few of the concerns. With the onset of self-driving cars, and its popularity in integrating them into electric vehicles leads to increase in safety both for the passengers inside the vehicle as well as the people outside. Since electric vehicles have not been widely used over an extended period of time to evaluate the failure rate of the powertrain of the EV, a general but definite understanding of motor failures can be developed from the usage of motors in industrial application. Since traction motors are more power dense as compared to industrial motors, the possibilities of a small failure aggravating to catastrophic issue is high. Understanding the challenges faced in EV due to stator fault in motor, with major focus on induction motor stator winding fault, this dissertation presents the following: 1. Different Motor Failures, Causes and Diagnostic Methods Used, With More Importance to Artificial Intelligence Based Motor Fault Diagnosis. 2. Understanding of Incipient Stator Winding Fault of IM and Feature Selection for Fault Diagnosis 3. Model Based Temperature Feature Prediction under Incipient Fault Condition 4. Design of Harmonics Analysis Block for Flux Feature Prediction 5. Flux Feature based On-line Harmonic Compensation for Fault-tolerant Control 6. Intelligent Flux Feature Predictive Control for Fault-Tolerant Control 7. Introduction to Machine Learning and its Application for Flux Reference Prediction 8. Dual Memorization and Generalization Machine Learning based Stator Fault Diagnosi

Lattice Element Method and its application to Multiphysics

In this thesis, a Lattice element modelling method is developed and is applied to model the loose and cemented, natural and artificial, granular matters subject to thermo-hydro-mechanical coupled loading conditions. In lattice element method, the lattice nodes which can be considered as the centres of the unit cells, are connected by cohesive links, such as spring beams that can carry normal and shear forces, bending and torsion moment. For the heat transfer due to conduction, the cohesive links are also used to carry heat as 1D pipes, and the physical properties of these rods are computed based on the Hertz contact model. The hydro part is included with the pore network modelling scheme. The voids are inscribed with the pore nodes and connected with throats, and then the meso level flow equation is solved. The Euler-Bernoulli and Timoshenko beams are chosen as the cohesive links or the lattice elements, while the latter should be used when beam elements are short and deep. This property becomes interesting in modelling auxetic materials. The model is applied to study benchmarks in geotechnical engineering. For heat transfer in the dry and full range of saturation, and fractures in the cemented granular media.How through porous media failure behaviours of rocks at high temperature and pressure and granular composites subjected to coupled Thermo hydro Mechanical loads. The model is further extended to capture the wave motion in the heterogeneous granular matter, and a few case studies for the wavefield modification with existing cracks are presented. The developed method is capable of capturing the complex interaction of crack wave interaction with relative ease and at a substantially less computational cost

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Geometrical accuracy improvement in flexible roll forming process by means of local heating

In the last decade the tendency to reduce vehicle weight due to rising fuel prices and environmental requirements, have pushed two main trends of research in the field of vehicle structure manufacturing. On the one hand, the development of new high strength steels allowed to reduce weight and increase the structural performance of vehicles. However, these materials exhibit low formability and high springback effect at room temperature, making dificult to form high strength steel accurate parts. For all these reasons it is necessary to develop exible and consumer-oriented manufacturing processes in order to allow the manufacturing of accurate parts in an economic way. In this context, the flexible roll forming process was developed, which combines all the advantages of conventional roll forming, allowing to manufacture continuously, profiles with variable cross section along its longitudinal direction. However, the flexible roll forming process is still under development and characteristic geometrical error of the process must be solved. Therefore, the current dissertation proposes and studies the reduction of geometrical errors created during the manufacture of flexible profiles using a thermo-mechanical process called heat-assisted flexible roll forming. Three have been the main fields of research conducted for this purpose. In the first section of the present dissertation, the quasi-static mechanical behavior of three ultra high strength steel sheets (MS1200, CP800 and DP600) and a soft steel sheets (DC01) are characterized by means of uniaxial tensile tests. These materials are used to validate the numerical models developed during the thesis. On the other hand, the CP800 material, selected to perform heat-assisted flexible roll forming experiments, is mechanically characterized at high temperatures. In order to determine the microstructural changes that take place and identify possible deformation mechanisms at high temperatures, the microstructure of the specimens tested at high temperature are analyzed by optical microscopy and X-ray diffraction methods. In the second section, numerical models of the conventional roll forming process and heat assisted flexible roll forming process are developed. Numerical models are used to develop and optimize the heat assisted flexible roll forming process. However, in order to check the reliability of the models, conventional roll forming trials results are compared with numerical results. In the last section, heat assisted flexible roll forming experiments are carried out using the flexible roll forming machine developed within the European Proform project. The results show a significant decrease of the web warping when the flexible profile is heat assisted.Ibilgailuen pisua gutxitzeko joera garbia izan da azken hamarkadan, ingurugiroarekiko legediak eta arrazoi ekonomikoak bultzatuta. Helburu horrek ibilgailuen egitura nagusien ikerkuntza bi norantza nagusitan bideratu du. Batetik, material arinen azterketan eta garapenean, eta bestetik, material berri horiek eraldatzeko prozesu berritzaleen ikerkuntzan. Alde batetik, erresistentzia espezifiko handiko materialeen erabilerak ibilgailuen pisuaren jaitsiera eta ezaugarri estrukturalen hobekuntza ekarri du. Halere, material hauek oso konformabilitate baxua eta errekuperazio elastiko handia dutenez, zaila egiten da geometrikoki forma egokia duten profilak ekoiztea. Arrazoi horiek guztiak direla eta, ekonomikoa den eta kontsumitzaileari egokituriko fabrikazio prozesu berrien garapena beharrezkoa egiten da. Ingurumari honetan, eta eskakizun guzti horiei erantzuna emateko, profilaketa arruntaren abantaila guztiak eta sekzio aldakorreko profilak sortzeko aukera uztartzen dituen prozesu berria sortu da, profilaketa aldakorra. Halere, profilaketa aldakorra oraindik garapen prozesuan izanik, prozesua berarenak diren akats geometriko bereziak konpontzeko beharra dago. Horregaitik, doktorego tesi honetan, akats geometriko horiek gutxitzeko helburuarekin, termikoki lagunduriko profilaketa aldakorra izeneko irtenbide termiko-mekanikoa proposatzen eta ikertzen da. Hiru ikerketa lerro nagusi jarraitu dira helburu hori lortzeko asmotan. Ikerkuntza lan honen lehenengo atalean, erresistentzi altuko hiru altzairuren (MS1200, CP800 eta DP600) eta altzairu arrunt baten (DC01) karakterizazio mekanikoa burutu da, trakzio saiakuntza kausiestatikoak burutuz. Material horiek doktoradutza tesian zehar garatu diren eredu matematikoak egiaztatzeko erabili dira. Bestalde, CP800 altzairua, termikoki lagundutako profilaketa aldakorreko esperimentazioa burutzeko aukeratua izanik, tenperatura altuetan ere mekanikoki karakterizatu da. Tenperaturak mikroegituran duen eragina eta eman daitezkeen deformazio mekanismoak aztertzeko asmotan, tenperatura altuetan entseatutako probetak mikroskopio optikoaz eta X-izpien difrakzioaz aztertu dira. Bigarrengo atalean, profilaketa arruntaren eta termikoki lagundutako profilaketa aldakorraren eredu matematikoak garatu eta egiaztatu dira. Eredu matematikoen emaitzak helburu horretarako sortu den profilatzeko makina arrunt batetan buruturiko entsegu esperimentalen emaitzekin aldaratu dira. Bestalde, entsegu hauek profilaketa prozesuan materialaren gogortasunak nola eragiten duen aztertzeko ere balio izan dute. Azkenik, termikoki lagunduriko profilaketa aldakorreko entsegu esperimentalak burutu dira, Proform Europear proiektuan zehar garatutako profilaketa aldakorreko makinan. Lortutako emaitzek akats geometrikoen hobekuntza adierazgarri bat erakusten dute, sekzio aldakorreko perfila termikoki lagundua izan denean.En la última década la tendencia a reducir el peso de los vehículos debido al encarecimiento de los combustibles y a los requerimientos medioambientales han marcado dos principales vías de investigación en el campo de la fabricación de estructuras para vehículos. Por un lado, el desarrollo de nuevos aceros de alta resistencia ha permitido la reducción del peso y el aumento de las prestaciones estructurales de los vehículos. Sin embargo, estos materiales presentan una baja conformabilidad y una gran recuperación elástica a temperatura ambiente, dificultando el conformado de piezas de acero de alta resistencia geométricamente precisas. Por todo ello, se hace necesario el desarrollo de procesos de fabricación flexibles y orientados al consumidor que permitan el conformado de piezas geométricamente precisas de una forma económica. En este contexto, se ha desarrollado el perfilado flexible o de sección variable, donde se combinan todas las ventajas del perfilado convencional, permitiendo la fabricación de forma contínua de perfiles con secciones cambiantes a lo largo de su dirección longitudinal. Sin embargo, al ser un proceso de fabricación todavía en proceso de desarrollo, existen errores geométricos característicos del proceso que deben ser resueltos. Por todo ello, en la presente te sis se propone y estudia la disminución de los errores geométricos creados durante la fabricación de perfiles flexibles mediante un proceso termo-mecánico, llamado perfilado flexible asistido térmicamente. Han sido tres las principales vías de investigación llevadas a cabo para para conseguir este objetivo: En un primer apartado, se ha caracterizado el comportamiento mecánico de tres tipos chapas de acero de ultra alta resistencia (MS1200, CP800 y DP600) y chapas de acero de embutición convencional (DC01), mediante ensayos de tracción uniaxial cuasi-estáticos. Estos materiales, han sido empleados para validar los modelos numéricos desarrollados durante la tesis doctoral. Por otro lado, el material CP800, elegido para realizar ensayos de perfilado flexible asistido térmicamente, se ha caracterizado mecánicamente a altas temperaturas. Con el objetivo de determinar los cambios microestructurales e identificar los mecanismos de deformación a altas temperaturas, se han analizado las microestructuras de las probetas ensayadas mediante microscopia óptica y difracción de rayos X. En un segundo apartado, se han desarrollado y validado modelos de simulación numérica del proceso de perfilado convencional y perfilado flexible asistido térmicamente. Los resultados de los modelos numéricos han sido contrastados mediante ensayos experimentales realizados en una perfiladora convencional desarrollada con este objetivo. Por otro lado, los ensayos de perfilado convencional han servido para determinar la influencia de la resistencia del material en los diferentes parámetros de proceso analizados. Los resultados de la simulación del proceso de perfilado asistido termicamente han servido para optimizar el proceso y la estrategia de calentamiento utilizada. En el último apartado, se han realizado ensayos experimentales de perfilado asistido térmicamente, en la perfiladora flexible desarrollada en el seno del proyecto Europeo Proform. Los resultados obtenidos, muestran una significativa disminución del error en la base del perfil, cuando el perfil flexible ha sido asistido térmicamente

Thermophysical Phenomena in Metal Additive Manufacturing by Selective Laser Melting: Fundamentals, Modeling, Simulation and Experimentation

Among the many additive manufacturing (AM) processes for metallic materials, selective laser melting (SLM) is arguably the most versatile in terms of its potential to realize complex geometries along with tailored microstructure. However, the complexity of the SLM process, and the need for predictive relation of powder and process parameters to the part properties, demands further development of computational and experimental methods. This review addresses the fundamental physical phenomena of SLM, with a special emphasis on the associated thermal behavior. Simulation and experimental methods are discussed according to three primary categories. First, macroscopic approaches aim to answer questions at the component level and consider for example the determination of residual stresses or dimensional distortion effects prevalent in SLM. Second, mesoscopic approaches focus on the detection of defects such as excessive surface roughness, residual porosity or inclusions that occur at the mesoscopic length scale of individual powder particles. Third, microscopic approaches investigate the metallurgical microstructure evolution resulting from the high temperature gradients and extreme heating and cooling rates induced by the SLM process. Consideration of physical phenomena on all of these three length scales is mandatory to establish the understanding needed to realize high part quality in many applications, and to fully exploit the potential of SLM and related metal AM processes

Improved micro-contact resistance model that considers material deformation, electron transport and thin film characteristics

This paper reports on an improved analytic model forpredicting micro-contact resistance needed for designing microelectro-mechanical systems (MEMS) switches. The originalmodel had two primary considerations: 1) contact materialdeformation (i.e. elastic, plastic, or elastic-plastic) and 2) effectivecontact area radius. The model also assumed that individual aspotswere close together and that their interactions weredependent on each other which led to using the single effective aspotcontact area model. This single effective area model wasused to determine specific electron transport regions (i.e. ballistic,quasi-ballistic, or diffusive) by comparing the effective radius andthe mean free path of an electron. Using this model required thatmicro-switch contact materials be deposited, during devicefabrication, with processes ensuring low surface roughness values(i.e. sputtered films). Sputtered thin film electric contacts,however, do not behave like bulk materials and the effects of thinfilm contacts and spreading resistance must be considered. Theimproved micro-contact resistance model accounts for the twoprimary considerations above, as well as, using thin film,sputtered, electric contact