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Vpliv posodobitve klimatskega sistema na energetsko učinkovitost objektov
Matic Raušl, 2012, undergraduate thesis

Abstract: V diplomskem delu je predstavljen problem prezračevanja in klimatizacije prostorov za reproduktivno medicino in ginekološko endokrinologijo Univerzitetnega kliničnega centra Maribor. Celoten obstoječi klimatizacijski sistem za ta oddelek je dotrajan in ne zagotavlja več optimalnih pogojev za delo in bivanje v bolnišnici. Na sistemu redno prihaja do tehničnih težav in je velik porabnik energentov. S temi težavami so povezani vzdrževalni stroški in stroški energije, ki so posledično zelo visoki. S pomočjo študija literature, opazovanja delovanja sistema, primerjave sistema s sodobnejšim in s finančnimi izračuni, sem prišel do spoznanja, da bi ob zamenjavi klimatskega sistema z sodobnejšim, letno prihranili za kar 49124,91 evrov stroškov in bi bila zamenjava smiselna.
Keywords: prezračevanje, klimatizacija, klimatizacijski sistem, vzdrževanje, energetska učinkovitost
Published: 20.11.2012; Views: 1217; Downloads: 211
.pdf Full text (921,10 KB)

Rapid prototyping processes give new possibilities to numerical copying techniques
Ivo Pahole, Igor Drstvenšek, Mirko Ficko, Jože Balič, 2005, original scientific article

Abstract: Due to the appearance of numerically controlled machine tools the conventional copying from physical model has almost lost its importance. Instead, the model of numerical copying is widely used. Until recently, geometry could be copied predominantly in the touching manner and the manufacture of copied - measured shapes on CNC machine tools mainly did not pose o problem. However, because of the introduction of optical copying of geometrical data it is possible to copy the shapes which, sometimes, cannot be made by conventional machining processes (small radii of curvature, negative angles, etc.). The paper describes how these problems can be solved with layered technology processes within a very short time.
Keywords: manufacturing technologies, prototype generation, rapid prototyping, numerical copying, CAD/CAm, digitalization
Published: 01.06.2012; Views: 926; Downloads: 59
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Basic solutions on shape complexity evaluation of STL data
Bogdan Valentan, Tomaž Brajlih, Igor Drstvenšek, Jože Balič, 2008, original scientific article

Abstract: Purpose of this paper is to present basic solutions on shape complexity, based on basic information of the STL data. Design/methodology/approach: Paper presents a few methods of mathematically evaluating the complexity of the shape. Methods vary from very simple based on the number of triangles in STL file, STL file size and the parts volume, to the more complex mathematical evaluation based on the basic relations of the STL data. Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic results on part complexity and can be used for further researches. Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results. Practical implications: In a rapidly developing field of manufacturing technologies choosing the optimal manufacturing procedure is a difficult and crucial decision. Usually the decision is based on experience evaluation that is fast and can be optimal. Usually, this method produces goods results, but in some cases this method can lead to cost increases and reduced economic efficiency without us even knowing that. Therefore, it is crucial, that a fast and simple solution is developed, by which the optimal way of manufacturing can be determined. Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.
Keywords: manufacturing systems, shape complexity, complex shapes, manufacturing optimization, engineering design, STL files, STL file parameters
Published: 01.06.2012; Views: 1179; Downloads: 35
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A model of simulation environment for prediction and optimisation of production processes
Igor Drstvenšek, Mirko Ficko, Ivo Pahole, Jože Balič, 2004, original scientific article

Abstract: Paper describes means and methods for computer based optimisation of production processes using a new approach based on technological database (TDB) with genetic algorithm incorporated into a database management system (DBMS). The TDB serves as a store of tools and machine tools from which they can be assigned to different work operations. Work operations are basic entities of orders placed into queues. The goal of the model is to find available resources from the TDB in order to empty the queue in shortest time with lowest costs. To this purpose the model consist the technological database whose DBMS includes a genetic algorithm based optimiser. It checks the orders queue and searches for appropriate combinations of tools and machine tools from the TDB, which can be combined into needed work operations. It also performs an optimisation of time and costs according to so called static parameters of tools and machine tools.
Keywords: production processes, simulation, process planning, technological databases, genetic algorithms
Published: 01.06.2012; Views: 1061; Downloads: 60
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A model of data flow in lower CIM levels
Igor Drstvenšek, Ivo Pahole, Jože Balič, 2004, original scientific article

Abstract: After years of work in fields of computer-integrated manufacturing (CIM), flexible manufacturing systems (FMS), and evolutionary optimisation techniques, several models of production automation were developed in our laboratories. The last model pools the discoveries that proved their effectiveness in the past models. It is based on the idea of five levels CIM hierarchy where the technological database (TDB) represents a backbone of the system. Further on the idea of work operation determination by an analyse of the production system is taken out of a model for FMS control system, and finally the approach to the optimisation of production is supported by the results of evolutionary based techniques such as genetic algorithms and genetic programming.
Keywords: computer integrated manufacturing, flexible manufacturing systems, evolutionary optimisation techniques, production automation, CIM hierarchy, technological databases, production optimisation, genetic algorithms, genetic programming
Published: 01.06.2012; Views: 1184; Downloads: 53
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Relational database as a cogitative part of an intelligent manufacturing system
Igor Drstvenšek, Mirko Ficko, Jože Balič, 2004, original scientific article

Abstract: An intelligent manufacturing system is intended to produce one or more subjects that it is designed for in an optimal way. This means that it has to find a proper production process to produce the subject in an optimal way. The manufacturing system can be called "intelligent" when it is able to find applicable optimisation criteria upon its past experiences thus improving its performance in future. Therefore, an intelligent manufacturing system needs capabilities to store data and make decisions upon them. Such a "brain" can be established by a proper design of a technological database and its database management system (DBMS). Examining all constitutive parameters of a work operation a model of a production process organization can be made, which can serve as a basis for a suitable database design. In addition, an application programme that will check the existence and availability of work operations in the database has to be added to the DBMS. What remains are some optimisation criteria upon which we will choose an operation among suitable and available work operations. This task is fulfilled by a genetic algorithm optimisation technique that would consider work operations' data as parameters of optimisation and on this basis search the optimal one out of the set of available operation.
Keywords: production processes, optimisation, relational database, database management systems, production automation, manufacturing system
Published: 01.06.2012; Views: 1074; Downloads: 58
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Development of a 3D printer for thermoplastic modelling
Bogdan Valentan, Dušan Pogačar, Tomaž Brajlih, Tjaša Zupančič Hartner, Ana Pilipović, Igor Drstvenšek, 2012, original scientific article

Abstract: Additive technologies are entering the market in all price segments and the development of new machines and materials is rapidly growing. Machines under 2000 EUR are more and more interesting for home and educational use. This paper presents the development of a 3D printer that shapes the parts layer by layer by depositing the material on a predefined position. The development is presented from the engineering point of view. The construction steps, the control and the actuator solutions are presented. The ABS plastic was analysed for its material properties. The 3D printer evolved from a prototype to the pre-production phase.
Keywords: polymers, rapid prototyping, additive technologies, 3D print
Published: 10.07.2015; Views: 627; Downloads: 76
.pdf Full text (1,37 MB)
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A fast method to predict the cooling time of wax for investment casting procedure
Bogdan Valentan, Ana Pilipović, Tomaž Brajlih, Peter Sever, Ivo Pahole, Mirko Ficko, Jože Balič, Igor Drstvenšek, 2012, original scientific article

Abstract: The investment casting of metal parts is a rapid tooling/manufacturing method for small series production, where wax pattern is produced separately and then extracted from the mould. The wax parts commonly used as patterns are usually obtained after wax casting silicone rubber moulds. The time needed for the wax to solidify is critical and difficult to predict. This article presents an experimental method for cooling-time determination using a simplified applicable solution (needed in hash industrial environment and short deadlines) based on real-life parts experience.
Keywords: odlivki, vosek, silikonski gumijasti modeli, čas hlajenja, hitra proizvodnja
Published: 10.07.2015; Views: 575; Downloads: 36
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Modeliranje in izdelava resekcijskih vodil za operacije ramenskega sklepa
Urška Kostevšek, 2012, master's thesis

Abstract: Obraba ramenskega sklepa je pogost problem sklepnih struktur okostja. Ena izmed metod zdravljenja je vstavitev endoproteze ramenskega sklepa. Klasičen operativni postopek smo s pomočjo računalniških orodij modificirali z razvojem resekcijskega vodila. Vodilo je pripomoček pri operaciji, ki omogoča njeno izvedbo s klasičnimi orodji, vendar kirurgu pomaga pri natančni določitvi resekcijskih ravnin. Vodilo je izdelano na podlagi predoperativne 3D-CT slike ramena bolnika, s pomočjo katere se pred posegom določijo operativni rezi, ki z resekcijo skozi šablono zagotovijo natančno lego endoproteze v danih anatomskih razmerah, saj določajo optimalno inklinacijo, retroverzo in globino humeralnega in glenoidalnega dela ramenske endoproteze. Rezultati kliničnega preverjanja nakazujejo, da vodilo zmanjšuje čas operacije, predvsem pa optimizira lego endoproteze v kostni strukturi, zaradi česar je operacija uspešnejša, zanesljivejša in predvsem zagotavlja boljše dolgoročno preživetje endoproteze.
Keywords: resekcijsko vodilo, ramenski sklep, endoproteza, modeliranje, vzvratno inženirstvo
Published: 05.07.2012; Views: 1681; Downloads: 283
.pdf Full text (3,74 MB)

Mitja Križnik, 2012, undergraduate thesis

Abstract: Pri izdelavi aluminijastih prototipov v tej diplomski nalogi bomo za izdelavo uporabili postopek litja z izgubljenim jedrom. Pri tem postopku se najprej izdela prototip s 3D printerjem. Nato na podlagi prototipa izdelamo silikonsko orodje, s pomočjo katerega bomo izdelovali voščene pramodele. Voščene pramodele bomo pritrdili na voščeno drevo, ga zalili z mavcem, izžgali vosek ter nato ulili aluminijevo zlitino v nastali kalup. S tem dobimo aluminijaste prototipe ohišja uparjalnika, ki so cilj diplomske naloge. Pri tem postopku se pojavlja nenatančnost izdelave, ki je posledica skrčkov materialov. Skrčke bomo ugotavljali in merili s pomočjo trirazsežnega skenerja ATOS II. Za funkcionalno testiranje novega načina gretja uparjalnika mora biti prototip izdelan znotraj zahtevanih toleranc, ki bodo omogočale montažo na preostalo ohišje in pravilno delovanje sklopa uparjalnika v avtomobilskih plinskih sistemih. Kazalci za prihodnost pa napovedujejo največji potencial dodajalnih tehnologij v izdelavi končnih izdelkov za potrebe biomedicine, letalstva, vesoljske tehnike.
Keywords: dodajalni postopki, SLS (selektivno lasersko sintranje), hitra izdelava prototipov, hitra izdelava orodij, izdelava končnih izdelkov, litje z izgubljenim jedrom
Published: 10.12.2012; Views: 1604; Downloads: 139
.pdf Full text (3,29 MB)

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