Evolutionary multi-objective decision support systems for conceptual design

Merged with duplicate record 10026.1/2328 on 07.20.2017 by CS (TIS)In this thesis the problem of conceptual engineering design and the possible use of adaptive search techniques and other machine based methods therein are explored. For the multi-objective optimisation (MOO) within conceptual design problem, genetic algorithms (GA) adapted to MOO are used and various techniques explored: weighted sums, lexicographic order, Pareto method with and without ranking, VEGA-like approaches etc. Large number of runs are performed for findingZ Dth e optimal configuration and setting of the GA parameters. A novel method, weighted Pareto method is introduced and applied to a real-world optimisation problem. Decision support methods within conceptual engineering design framework are discussed and a new preference method developed. The preference method for translating vague qualitative categories (such as "more important 91 , 4m.9u ch less important' 'etc. ) into quantitative values (numbers) is based on fuzzy preferences and graph theory methods. Several applications of preferences are presented and discussed: * in weighted sum based optimisation methods; s in weighted Pareto method; * for ordering and manipulating constraints and scenarios; e for a co-evolutionary, distributive GA-based MOO method; The issue of complexity and sensitivity is addressed as well as potential generalisations of presented preference methods. Interactive dynamical constraints in the form of design scenarios are introduced. These are based on a propositional logic and a fairly rich mathematical language. They can be added, deleted and modified on-line during the design session without need for recompiling the code. The use of machine-based agents in conceptual design process is investigated. They are classified into several different categories (e. g. interface agents, search agents, information agents). Several different categories of agents performing various specialised task are developed (mostly dealing with preferences, but also some filtering ones). They are integrated with the conceptual engineering design system to form a closed loop system that includes both computer and designer. All thesed ifferent aspectso f conceptuale ngineeringd esigna re applied within Plymouth Engineering Design Centre / British Aerospace conceptual airframe design project.British Aerospace Systems, Warto

Procena rizika po zdravlje vozača, od vibracija nastalih pri eksploataciji traktora

Drivers of agricultural tractors are exposed during operation, a number of harmful effects, such as high or low temperatures, high humidity, dust, noise, etc. Among the adverse factors there are vibrations from the engine, during the operating, and are transmitted through the seat, floor and commands of the vehicle to the driver's entire body. Exposure to high levels of vibration, in the long term, can lead to serious health problems and permanent damage of the driver's health. Therefore, the health risk assessment of vibration for the professional tractor drivers is extremely important in terms of developing of protection mechanisms. Although the usual procedure of risk assessment involves the study of all hazards and harmful effects that may occur in a specific workplace, in this work is done only health risk assessment tractor drivers from the harmful effects of vibration, whereby the assessment used a simple 5x5 matrix method. Evaluation was carried out using the results of measuring the level of exposure to the driver in real operating conditions, on the different tractors. Part of the results is available from international studies dealing with this issue, a part of the result its own vibration measurements on the domestic IMT tractors. The risk assessment showed that drivers and operators of heavy machinery are working in conditions of increased risk of vibration. For this reason, it`s given a number of organizational and technical measures that should be taken by employer to reduce increased risk of or completely reduced risk.Vozači poljoprivrednih traktora izloženi su, tokom rada, mnogobrojnim štetnim faktorima, među kojima se nalaze i vibracije. U pitanju su opšte vibracije koje nastaju u motoru, pri radu traktora, i prenose se, preko sedišta, poda i komandi vozila do celog tela vozača (whole body vibration). Izloženost ovim vibracijama, u dužem periodu, može dovesti do ozbiljnih zdravstvenih problema vozača. Zato je procena rizika po zdravlje od vibracija, kod profesionalnih vozača traktora, izuzetno bitna sa aspekta razvijanja zaštitnih mehanizama. Iako uobičajena procedura procene rizika podrazumeva proučavanje svih opasnosti i štetnosti koje se mogu pojaviti na određenom radnom mestu, u radu je urađena samo procena rizika po zdravlje vozača traktora od štetnog delovanja vibracija. Za ovu procenu korišćen je matrični model 5x5, pri čemu je procena pokazala da vozači i rukovaoci teškom mehanizacijom rade u uslovima povećanog rizika od vibracija. Iz tog razloga dato je nekoliko organizacionih i tehničkih mera koje je poslodavac dužan da preduzme kako bi se povećani rizik smanjio ili potpuno redukovao

VIBRATION FEATURE EXTRACTION METHODS FOR GEAR FAULTS DIAGNOSIS -A REVIEW

The key point of condition monitoring and fault diagnosis of gearboxes is a fault feature extraction. The study of fault feature detection in rotating machinery from vibration analysis and diagnosis has attracted sustained attention during past decades. In most cases determination of the condition of a gearbox requires study of more than one feature or a combination of several techniques. This paper attempts to survey and summarize the recent research and development of feature extraction methods for gear fault diagnosis, providing references for researchers concerning with this topic and helping them identify further research topics. First, the feature extraction methods for gear faults diagnosis are briefly introduced, the usefulness of the method is illustrated and the problems and the corresponding solutions are listed. Then, recent applications of feature extraction methods for gear faults diagnosis are summarized, in terms of industrial gearboxes. Finally, the open problems of feature extraction methods for gear fault diagnosis are discussed and potential future research directions are identified. It is expected that this review will serve as an introduction summary of vibration feature extraction methods for gear faults diagnosis for those new to the concepts of its applications to gear fault diagnosis based on vibratio

Web-based laboratory for collaborative and concurrent CAD designing, assembling, and practical exercising on distance

Kolaborativno modeliranje dislociranih učesnika postaje neophodan segment pravovremenog CAD projektiranja. Kompleksni sustavi namijenjeni kolaborativnom projektiranju su velika investicija i iz tog razloga njihova uporaba nije česta. Iako većina CAD programa ima module za suradnju, takva rješenja mogu predstavljati veliki trošak, posebice obrazovnim institucijama koje obučavaju veliki broj studenata. Između ostalog, spomenuti moduli uglavnom rade u određenom CAD programu i pružaju podršku za uvoz i izvoz ograničenog broja CAD formata. U ovom je radu prikazano rješenje otvorenog koda koje nadilazi prethodno navedene probleme. Predloženo rješenje omogućava praktičan rad na daljinu, kombinirajući najčešće rabljene CAD alate u industrijskom dizajnu. U radu je opisana uporaba virtualnog laboratorija za brzo projektiranje izvođenjem praktičnih vježbi, arhitektura predloženog rješenja, modeliranje laboratorija i metode za kreiranje njegovih funkcija. Praktičan primjer prikazuje kolaborativno sklapanje zrakoplova između udaljenih sudionika, s dijelovima modeliranim u različitim CAD paketima. Upotrebljivost laboratorija prikazana je izradom prototipa sklopljenog modela na 3D tiskaču i njegovog završnog testa u zračnom tunelu. Dana je kvalitativna i kvantitativna evaluacija predloženog rješenja. U zaključnom dijelu, dana su predviđanja po pitanju uporabe tehnologija za izgradnju virtualnih laboratorija i virtualnih sklopova.Collaborative CAD of distant modelling is a today’s necessity for realization in a timely manner. This need arises even within educational institutions, where investments in the development of technologies to support collaborative distance learning are still trivial. Most CAD programs used in engineering have modules for collaboration. However, these solutions are expensive, especially for educational institutions that have a large number of students. The mentioned modules generally work within a specific CAD platform and support import and export of a limited number of CAD formats. In this paper, we present an open-source solution that overcomes these problems. It implements practical work at a distance by combining most commonly used CAD platforms in engineering. In this paper, we describe how to use virtual laboratory for rapid designing through execution of practical exercises. The architecture of the proposed solution, the modelling of the laboratory and methods for creating its functions are described. Also, given is a tangible example of collaborative aircraft assembly between distant students, with parts modelled in different CAD packages, and the usability of labs presented through prototype builds on 3D printer and the final test in the wind tunnel. Qualitative and quantitative evaluations were conducted. Conclusions set the direction of the future development using various technologies for building virtual assembly laboratory

Утицај чистоће натуралног семена lуцерке на рандман дораде

To improve seed quality, harvested seed must be transported to processing facility. Harvested, naturalized alfalfa seed contains many different particles such as weed seed, seed of other raised plants ant inert matter. In the processing of small grained legumes, output is in direct dependence with percent of weed species and of quality of other particles in naturalized seed. High percent of purity of naturalized alfalfa seed is not always a guarantee for high processing output. It primary depends on species of present weed in naturalized seed. High purity seed with low percent of weed leads to high output. Weed usually makes processing more difficult and costly. In this study, was analyzed the effect of quantity of particles on utilization of alfalfa seed and two different kind of seed purity, that were processed on the same system of machine.У процесу дораде семена ситнозрних легуминоза висина рандмана семена директно зависи од заступљености коровских врста и осталих примеса у натуралном семену. Висок степен чистоће натуралног семена луцерке није увек гаранција и високог рандмана дораде, чак и при малом садржају корова, већ он првенствено зависи од врсте присутних корова у натуралном семену. Већи садржај штетних корова у натуралном семену луцерке са високом чистоћом смањује укупну количину дорађеног семена, отежава и поскупљује дораду. У раду је дата анализа утицаја садржаја примеса у натуралном семену луцерке, на искоришћење семена, односно добијену количину семена, при чему се дорада две различите чистоће семена обављала на истом систему машина за дораду

THE CHARACTERISTICS OF FRUITFULNESS OF SOME INTERSPECIES GRAPEVINE CULTIVARS

The results of important agro-biological and technological characteristics of three grapevine interspecies cultivars (Medina, Gecej Zamatos, and Kristala) are presented in this study. The following parameters were monitored: the total number of developed shoots, the number of fertile shoots, the number of bunch per vine, grape yield, fertility coefficient, the average bunch weight, yield per hectare, bunch and berry structural indicators and grape quality expressed through the content of sugar in must. Statistically significant differences were determined between the examined varieties regarding following characteristics: the number and yield of bunches per vine, structural indicators of berries and sugar content in must. The analysis of the obtained results related with the analyzed grape varieties in the agro-ecological conditions of Northern Bosnia showed that those varieties can successfully be cultivated in similar or identical agro-ecological conditions

On the Use of Conformal Models and Methods in Dosimetry for Nonuniform Field Exposure

Numerical artifacts affect the reliability of computational dosimetry of human exposure to low-frequency electromagnetic fields. In the guidelines of the International Commission of Non-Ionizing Radiation Protection (ICNIRP), a reduction factor of 3 was considered to take into account numerical uncertainties when determining the limit values for human exposure. However, the rationale for this value is unsure. The IEEE International Committee on Electromagnetic Safety has published a research agenda to resolve numerical uncertainties in low-frequency dosimetry. For this purpose, intercomparison of results computed using different methods by different research groups is important. In previous intercomparison studies for low-frequency exposures, only a few computational methods were used, and the computational scenario was limited to a uniform magnetic field exposure. This study presents an application of various numerical techniques used: different Finite Element Method (FEM) schemes, Method of Moments (MoM) and Boundary Element Method (BEM) variants and finally by using a hybrid FEM/BEM approach. As a computational example, the induced electric field in the brain by the coil used in transcranial magnetic stimulation is investigated. Intercomparison of the computational results are presented qualitatively. Some remarks are given for the effectiveness and limitations of application of the various computational methods

Computer Simulation

The first chapter provides an overview of the development of a novel agent-based simulation model of socio-environmental innovation diffusion. The second chapter shows the study about rendering of colours with three rendering engines. The third and fourth chapters are devoted to modelling clothes at different levels. The fifth chapter describes the modelling of computer simulation in the optimization of bioprocess technology. Chapters 6 and 7 formulate a physical model of deformation of steel and idea of constructing a scientific workshop focused on high-temperature processes. Chapter 8 formulates surrogate models. Chapter 9 shows computer simulation of high-frequency electromagnetic fields. Chapter 10 proposes the modelling of the task allocation problem by the use of Petri Nets. Chapter 11 presents various scenarios whose ranking is done according to defined criteria and weight coefficients

Virtual Learning

The first chapter provides an overview of the popular systems for distance learning. In the second chapter, a review of all major social and economic activities in order to improve the system of virtual learning is given. The third chapter deals with the influence of technology in the management of educational institutions. The fourth chapter provides an overview of the graphic communication. The fifth chapter confirms that quality assurance remains an integral and indispensable part of the process of virtual learning. The sixth and seventh chapters are dedicated to health and mutual communication about health problems and causes. The eighth and ninth chapters are dedicated to massive open online courses (MOOC). The tenth chapter refers to the widespread use of virtual reality in industrial environments