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Application of group technology in complex cluster type organizational systems
Slobodan Morača, Miodrag Hadžistević, Igor Drstvenšek, Nikola Radaković, 2010, original scientific article

Abstract: The aim of this research was to contribute to the development of structural design procedures of complex - cluster type organizational systems. Industrial clusters can help companies to improve their own market positions, effectiveness, productivity and product quality. Organization of the production process in a company is an extremely complex process itself, and when it is transferred to the cluster level, the result is a complex task which is difficult to solve. For that purpose, this paper analyses the conditions and possibilities that would enable those structures to adapt to changes in the surroundings - flexibility and management adequacy of production and organizational structures - by lowering the degree of complexity. For the time being, no simple models which would enable an increase of process effectiveness in complex organizational units like clusters have been developed. One of the possible solutions which would decrease the complexity of flows and increase process effectiveness within an industrial cluster is the application of Group approach.
Keywords: industrial clusters, group technology, planning, work cells, complexity, flexibility
Published: 31.05.2012; Views: 1249; Downloads: 24
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Neural network based manufacturability evaluation of free form machining
Marjan Korošec, Jože Balič, Janez Kopač, 2005, original scientific article

Abstract: Most CAD/CAM and computer-aided process planning systems manipulate all geometrical features on the part equally. In the area of free form machining, lack of efficient methodology for assessing the degree of manufacturing pretentiousness of free form features is still noticeable. Developing this methodology inside CAD/CAM systems brings the following benefits to the tool shop praxis: it minimizes the number of set-ups and tool changes and at the same time ensures the right sequence of machining strategies in order to achieve the best possible surface quality in the machining area. Based on this assessment, the CAD/CAM process will also be greatly simplified. When there are an increased number of non-prismatic and non-cylindrical features, this problem is even more exaggerated, and its solution cannot be found in the framework of analytical mathematics. This paper reports a neuro-fuzzy model that uses the concept of "feature manufacturability" to identify and recognize the degree of "pretentiousness-difficulty of machining". The model is created by means of the construction of parametric fuzzy membership functions, based on neural networks learning process. This makes possible simultaneous evaluation of features complexity in a CAD model and manufacturing capability in an environment description model.
Keywords: index of machining complexity
Published: 01.06.2012; Views: 814; Downloads: 63
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Encyclopedia of complexity and systems science
dictionary, encyclopaedia, lexicon, manual, atlas, map

Abstract: Encyclopedia of Complexity and Systems Science provides an authoritative single source for understanding and applying the concepts of complexity theory together with the tools and measures for analyzing complex systems in all fields of science and engineering. The science and tools of complexity and systems science include theories of self-organization, complex systems, synergetics, dynamical systems, turbulence, catastrophes, instabilities, nonlinearity, stochastic processes, chaos, neural networks, cellular automata, adaptive systems, and genetic algorithms. Examples of near-term problems and major unknowns that can be approached through complexity and systems science include: The structure, history and future of the universe; the biological basis of consciousness; the integration of genomics, proteomics and bioinformatics as systems biology; human longevity limits; the limits of computing; sustainability of life on earth; predictability, dynamics and extent of earthquakes, hurricanes, tsunamis, and other natural disasters; the dynamics of turbulent flows; lasers or fluids in physics, microprocessor design; macromolecular assembly in chemistry and biophysics; brain functions in cognitive neuroscience; climate change; ecosystem management; traffic management; and business cycles. All these seemingly quite different kinds of structure formation have a number of important features and underlying structures in common. These deep structural similarities can be exploited to transfer analytical methods and understanding from one field to another. This unique work will extend the influence of complexity and system science to a much wider audience than has been possible to date.
Keywords: cellular automata, complex networks, computational nanoscience, ecological complexity, ergodic theory, fractals, game theory, granular computing, graph theory, intelligent systems, perturbation theory, quantum information science, system dynamics, traffic management, chaos, climate modelling, complex systems, dynamical sistems, fuzzy theory systems, nonlinear systems, soft computing, stochastic processes, synergetics, self-organization, systems biology, systems science
Published: 01.06.2012; Views: 1609; Downloads: 82
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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: 1288; Downloads: 38
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Spatial rotation and recognizing emotions : gender related differences in brain activity
Norbert Jaušovec, Ksenija Jaušovec, 2008, original scientific article

Abstract: In three experiments, gender and ability (performance and emotional intelligence) related differences in brain activity - assessed with EEG methodology - while respondents were solving a spatial rotation tasks and identifying emotions in faces were investigated. The most robust gender related difference in brain activity was observed in the lower-2 alpha band. Males and females displayed an inverse IQ-activation relationship in just that domain in which they usually perform better: females in the emotional intelligence domain, and males in the visuospatial ability domain. A similar pattern of brain activity could also be observed for the male/female respondents with different levels of performance and emotional IQ. It was suggested that high ability representatives of both genders to some extent compensate for their inferior problem solving skills (males in emotional tasks and females in spatial rotation tasks) by increasing their level of attention.
Keywords: psychology, cognitive processes, emotional intelligence, EEG activities, problem complexity, brain, memory, spatial rotation, gender, event-related desynchronization
Published: 07.06.2012; Views: 1466; Downloads: 52
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The Complexity of Cryptography in Literature
Sonja Sedej, 2016, master's thesis

Abstract: Cryptography first appeared approximately four thousand years ago; it has developed and improved throughout history. Cryptography has an important role in the modern world. Cryptography has been a part of our lives for nearly four thousand years; nevertheless, the first book on cryptography did not appear until 1499, when John Tritheim published a collection of codes used in some European courts. Today, cryptography affects us in many seen and unseen forms and shapes. Therefore, I am not surprised to see that it is commonplace in fiction. The purpose of this thesis is not to study the light summer reading that has lately filled the bookshelves, but to systematically research the complexity of cryptography in different literary genres. In The Complexity of Cryptography in Literature, I analyze cryptography in English literature throughout the past two centuries. My thesis is, for many reasons, written in English; the study of English and American Literature, an English speaking mentor and researching literature written in English. Using analysis and synthesis I study two secondary theoretical sources, Codes and Ciphers – A History of Cryptography written by Alexander D'Agapeyeff and Codes, Ciphers and Secret Writing written by Martin Gardner. At the same time I introduce the appropriate terminology which is necessary for further understanding. The thesis summarizes and presents the history of cryptography. The latter is researched using the method of analysis and synthesis in The Code Book by Simon Sing and The Code-Breakers by David Kahn. Using the basic methods and history of cryptography, I will show that many methods of cryptography are described in literature; these are closely related to cryptography’s historical development. Furthermore, I propose that these methods are used in a wide spectra of literary genres; at the same time I will show that mostly simple or simplified methods of cryptography are used in literature; otherwise, they would not be accessible to the average reader. The thesis analyzes the complexity of cryptography in six different works of literature with reference to standard mathematical models of cryptography. I analyze the above mentioned works of literature, and using classification and mathematical methods, I process and present the appearance of cryptography in individual works (the methods and their correctness); then, using historical and comparative methods, I research the relationship between cryptographic methods used in literature and actual historical use of cryptography. Further on, I use various methods (the mathematical method, the method of analysis and synthesis, the method of interpretation, and the descriptive method) to present the complexity of cryptographic methods in literature.
Keywords: cryptography, code, cipher, complexity, fiction
Published: 26.08.2016; Views: 1226; Downloads: 79
.pdf Full text (2,49 MB)

On the packing chromatic number of Cartesian products, hexagonal lattice, and trees
Boštjan Brešar, Sandi Klavžar, Douglas F. Rall, 2007, original scientific article

Abstract: Pakirno kromatično število ▫$chi_{rho}(G)$▫ grafa ▫$G$▫ je najmanjše število ▫$k$▫, tako da lahko množico vozlišč grafa ▫$G$▫ razbijemo v pakiranja s paroma različnimi širinami. Dobljenih je več spodnjih in zgornjih meja za pakirno kromatično število kartezičnega produkta grafov. Dokazano je, da pakirno kromatično število šestkotniške mreže leži med 6 in 8. Optimalne spodnje in zgornje meje so dokazane za subdividirane grafe. Obravnavana so tudi drevesa ter vpeljana monotona barvanja.
Keywords: matematika, teorija grafov, pakirno kromatično število, kartezični produkt grafov, šestkotniška mreža, subdividiran graf, drevo, računska zahtevnost, mathematics, graph theory, packing chromatic number, Cartesian product of graphs, hexagonal lattice, subdivision graph, tree, computational complexity
Published: 10.07.2015; Views: 459; Downloads: 58
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Development of a part-complexity evaluation model for application in additive fabrication technologies
Bogdan Valentan, Tomaž Brajlih, Igor Drstvenšek, Jože Balič, 2011, original scientific article

Abstract: Klasičnim odrezovalnim postopkom so se v zadnjih letih pridružili tako imenovani dodajalni postopki (slojevite tehnologije ali po domače 3D-tiskalniki). Če smo še pred leti vsaj okvirno vedeli kateri postopek izbrati za kateri izdelek, pa danes, ob upoštevanju vedno širše palete slojevitih tehnologij, temu ni več tako in le redki posamezniki še zmorejo slediti razvoju na tem izredno živahnem in hitro rastočem področju. Predstavljen je način določanja kompleksnosti izdelka na osnovi 3D-modela in uporaba izračuna pri izbiri izdelovalnega postopka ter določanju časa poobdelave pri določenih slojevitih tehnologijah. Članek opisuje osnovne značilnosti formata STL kot izhodne CAD-datoteke, ki predstavlja osnovo za analizo in razvoj postopkov določanja kompleksnosti oblike samega modela. Predstavljenih je več modelov iz realnega okolja, na katerih je izvedena analiza vhodnih podatkov in postopek določanja kompleksnosti oblike. Predstavljeni so aktualni izdelovalni postopki, primerni tako za izdelavo unikatnih izdelkov kot tudi za serijsko izdelavo, s posebnim poudarkom na slojevitih tehnologijah. Na osnovi temeljnih lastnosti izdelovalnih tehnologij so analizirani testni modeli in s pomočjo ocene kompleksnosti določeni primerni postopki izdelave oziroma čas, potreben za poobdelavo posameznega izdelka, izdelanega po postopkih slojevitih tehnologij. Rezultati so primerljivi z izkustveno določitvijo izdelovalnega postopka na osnovi ocene strokovnjakov, tako da je ob manjših dodelavah metoda tudi praktično uporabna. Sistem dokaj natančno izloči modele, ki jih je moč izdelati po postopku struženja, prav tako je ustrezno določena meja za uporabo rezkalnega stroja. Pri slojevitih tehnologijah enoznačno izbiro omejuje dejstvo, da te tehnologije v večini primerov omogočajo izdelavo izdelkov ne glede na njihovo kompleksnost. Izbira se je tako omejila na dve skupini, in sicer slojevite tehnologije, pri katerih je potreben dodaten podporni material, in slojevite tehnologije, pri katerih podporni material ni potreben, oziroma ga je mogoče reciklirati. Pri izbiri izdelovalnega postopka bi, ob upoštevanju določenih dodatnih omejitev posameznih slojevitih tehnologij, bila mogoča natančnejša izbira glede na kriterije, kot so čas izdelave, proizvodni stroški, material idr., vendar bi to zahtevalo aktualno bazo podatkov o samih postopkih. Sam način izračuna je bil izbran zaradi razmeroma preprostega izračuna in dokaj natančnega določanja kompleksnosti. Uporaba kompleksnosti za določanje izdelovalnega postopka pred tem ni bila raziskana. S problemom določanja časa poobdelave se danes srečujemo pri praktično vseh slojevitih tehnologijah, ta dejavnik pa bistveno vpliva tako na celoten čas izdelave kot tudi na ceno izdelka. Predstavljena rešitev omogoča izračun časa poobdelave na uporabniku razumljiv način in ob upoštevanju individualnih vplivov specifične naprave s preprosto primerjalno metodo glede na čas poobdelave testnih modelov.
Keywords: rapid prototyping, STl, complexity, shape, layered technology, technology selection
Published: 10.07.2015; Views: 631; Downloads: 72
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Quantifying soil complexity using network models of soil porous structure
Marko Samec, A. Santiago, J. P. Cardenas, R. M. Benito, A. M. Tarquis, Sacha Jon Mooney, Dean Korošak, 2013, original scientific article

Abstract: This paper describes an investigation into the properties of spatially embedded complex networks representing the porous architecture of soil systems. We suggest an approach to quantify the complexity of soil pore structure based on the node-node link correlation properties of the networks. We show that the complexity depends on the strength of spatial embedding of the network and that this is related to the transition from a non-compact to compact phase of the network.
Keywords: soil complexity, soil pore networks, complex systems
Published: 21.07.2017; Views: 527; Downloads: 205
.pdf Full text (3,85 MB)
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