2005/11 Scientific papers, Series B
Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/38182
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Článek Otevřený přístup peer-reviewedpublished Dynamics of a two - phase fluid alternating flow (FAF) mechanism with a linear hydraulic motor(Univerzita Pardubice, 2006) Turza, Jozef; Gullerová, MonikaU klasických hydraulických mechanizmov je prietok kvapaliny vo vedení medzi hydrogenerátorom a hydromotorom jednosmerný. V mechanizmoch so striedavým prietokom kvapalina vo vedení vykonáva vratný pohyb. Tlak a prietok má v ustálenom stave periodický priebeh. Mechanizmov so striedavým prietokom kvapaliny, (ďalej len SPK), je z hl'adiska počtu fáz viacej druhov. Najväčšie uplatnenie nachádzajú dvojfázové mechanizmy so SPK. Sú vhodné všade tam, kde je potrebný trvalý striedavý pohyb výkonného člena, ako sú napr. pol'nohospodárske kosačky, vytriasacie mechanismy strojov, textilné tkacie stavy, zariadenia pre únavové skúšky a pod. Oproti klasickým vačkovým, alebo kl'ukovýmmechanizmom majú výhodu nezávislého priestorového usporiadania na strojnom zariadení a jednoduchú možnosť ochrany voči preťaženiu. Pre posúdenie funkčných vlastností dvojfázového mechanizmu je dôležitá jeho dynamická analýza, urobená v predloženom príspevku.Článek Otevřený přístup peer-reviewedpublished Practical aspects of JIT(Univerzita Pardubice, 2006) Průša, Petr; Tilkeridis, David; Kampf, RudolfIn today’s production practice the concept of JIT is connected to many factors which significantly decide its success or failure. These factors can be understood both like premises and like consequences. To find and describe these factors needs deep analysis and long practical surveys. Generally the core of these factors can be found in the concept of lean production. Before implementing JIT in live, mainly following factors (methods) shall be considered: Pull scheduling in Heijunka concept, Rapid setup, TQM, OEE, Jidoka and program of 5S and 3M. Each company to run JIT shall decide the prevention policy and necessary steps in order to avoid problems which may occur shortly after the implementation phase of JIT. If these factors are not well taken into account, the JIT concept itself will be a good indicator of company weaknesses (e.g. bad quality, long setup of machines, unreliable supplier) which will guarantee occur once the stock level goes down, but company will suffer from these quite a long time and finally may give up JIT at all. Nowadays kanban can be proposed as a useful driver of JIT in most companies, but the concept of this method needs precise rules and strict follow-up activities in practice.Článek Otevřený přístup peer-reviewedpublished Classification based on stable fuzzy decision tree method(Univerzita Pardubice, 2006) Levashenko, Vitaly; Kovalík, Štefan; Matiaško, KarolDecision tree induction is one of useful approaches for extracting classification knowledge from set instances. Considerable part of these instances obtains from formal analysis and modeling of human activities, which has fuzzy nature. It is often the case that real-world tasks can be handled easily by humans, they are often too difficult to be handled by machines. Fuzzy logic allows us to describe this problem. Fuzzy decision tree is a very popular method for fuzzy classification. We introduced term of cumulative information estimations based on Theory of Information approach. We used these cumulative estimations for synthesis of different criteria of decision tree induction. Usage these criteria allow us to produce new type of trees. In this paper we introduce Stable Ordered Fuzzy Decision Tree (FDT). The tree is oriented to parallel and stable processing of input attributes with differing cost. Usage this FDT allows us to realize a sub-optimal classification. Such classification detect a sequence of checks of input attributes with minimize the check-up cost. Also we introduce transformation process from FDT to fuzzy rules set. The results of this paper may be used for design of fuzzy decision-making or expert systems, which based on fuzzy rules set “if x is A and y is B then z is C”Článek Otevřený přístup peer-reviewedpublished Corporate identity as one of the important management activity(Univerzita Pardubice, 2006) Strišš, Jozef; Vodák, JozefPaper is dealing with Corporate identity (CI) as one of the important management processes in marketing. We try to show CI history, principles, possibilities and experiences of using it in the context and conditions of Slovak republic. This article offers a set of useful rules for successful implementation CI in the organisation. This paper characterises individual parts of Corporate identity as the part of managerial process known as effective marketing communication of those organizations that want to increase their competitiveness.Článek Otevřený přístup peer-reviewedpublished Future mobility development in passenger transport(Univerzita Pardubice, 2006) Melichar, Vlastimil; Salava, Daniel; Chmelař, MartinThis article describes basic factors of development and modelling of future mobility in passenger transport. Mobility development models are constrained by two basic factors, which represent travel time budget and travel money budget. Model and scenario of total mobility development is function of fixed travel money budget and travel time budget. By creation of model and future mobility development scenario in particular transport modes, we work on determination of particular transport mode shares and on four constraining factors. These factors are fixed travel time budget, path dependence, urban land-use patterns and balancing equation of total traffic volume. By model construction we examine at first two budget constraints of passenger – travel time budget and travel money budget, that are core elements of model methods. In further sequence we estimate future demand for services, that are offered by state, it means total mobility. Then we estimate share of offered mobility for each main mode of motorized transport (in CR conditions we speak about bus, railway and individual car passenger transport). These estimations are conducted overall for whole country or region and there are made scenario sensitivities form changes of the most important or uncertain presumptions. Generally mobility development models are projected to make possible formularization e.g. aggregate (regional or national) and long-term scenario. In essence we work on transport planning tradition and model explains, how passengers can select particular transport modes by satisfying their demand for mobility (term “mobility” used in model represents traffic volume measured by personal kilometres). But this model requires aggregated data. The aim of this model is not calculation of detailed estimations of travel distances and vehicles speeds, but rather total mobility prediction and prediction of offered share of each transport mode (so called modal split) within state and in aggregated regions in distant future. Future mobility development is determined by specific values of each transport mode in certain region or state. Within global mobility air transport share will increase in future, but other transport modes shares will decrease. In case of regional prognosis it is estimated that traffic volume share operated by conventional railways and HST has identical development in all world regions. However this uniform trend is estimated in no scenarios of cars and buses, although transparent trends are evident for these transport modes in majority of regions. In compliance with mobility future development slower transport modes will be substituted by faster. On permanently higher mobility levels then car share decreases according to growth of faster transport modes need (especially air transport) for satisfaction of increasing demand for mobility within fixed travel time budget. Multiple growth in mobility per capita cause demands of extreme mobility which proves by more frequent commuting for longer distances from place of living. Because extreme mobility depends on approach to high-speed transport modes, sparse inhabited areas will remain in certain regions. It relates to areas where travelling to traffic junctions (airports and stations of high-speed trains) is time demanding in HST system. By means of traffic volume prediction (car, bus, railway and high-speed transport, especially air and railway), the number of travels is estimated in distant future, used transport modes, e.g. within EU, in particular state or regions. Answers of these questions are decisive for long-term transport infrastructure planning and for mobility impacts assessment e.g. on environment. These matters are also the centre of interest by future market extension estimating for transport services technical equipment. We make efforts to create simple, but radical model, which shows probable answers of these questions. Reply of these questions requires construction of large-scale long-term models of transport system. But this mobility need very sharply contrasts with capacities of existing modeling techniques. Regional and urban transport models, which are the most intensive developed tools of transport planning must be orientated to prediction of local transport demand, flows and costs. These instruments optimalize direct traffic flows by cost minimization or consumer (passenger) utility maximization. They calculate with transport system details like e.g. numbers of cars using roads during several times and average speeds of location of lately built-up transport infrastructure. Essential detailed effect is also the fact that these models are based on big mutually related variables as car ownership, loading and vehicles utilization, travel banded charges, transport modes relative prices, urban travel speeds and passengers income. Regarding insufficient knowledges of relations among these variables, these multi-variation methods quickly degrade in distant future plans. Original requirements of transport planning models make these methods more inadequate tools for long-term scenarios development.Článek Otevřený přístup peer-reviewedpublished Subjects of transportation processes and their relationships(Univerzita Pardubice, 2006) Cempírek, Václav; Kampf, RudolfThis article was created as a part of researched grant project (GA ČR) „Transportation - logistical processes outsourcing“ on the Jan Perner Transport Faculty, University of Pardubice. The subjects are described in this article that are related to problem of selection of the form of transport as a part of transportation processes (customers, transport operators, forwarders, state (society) and relationships between the participants of transportation processes. Two basic models of selection of form of transport (Classic economical model and Model of total logistic costs ) are described in the next part of this article.Článek Otevřený přístup peer-reviewedpublished Impact of correlated samples loss on VoIP quality(Univerzita Pardubice, 2006) Klimo, Martin; Bachratá, KatarínaQuality of the IP telephony service can be measured as a composition of many parametres. Some of the parametres of quality of IP telephony service can be measured by secondary characteristics of difference between received and transmitted signal. The aim of this paper is to derive estimations for mean power of noise. Using non orthogonal basis the speech signal can be modeled as a cyclostationary random proces. The case of zero sample stuffing is studied. The packet loss is modeled as a correlated samples loss. As a mathematical model of this correlation the Gilbert model is used.Článek Otevřený přístup peer-reviewedpublished Vlastnosti hydraulického tlumiče vozidel(Univerzita Pardubice, 2006) Koreisová, Gabriela; Koreis, JosefV příspěvku je proveden výpočet časového průběhu kmitání kola a kmitání karoserie při přejezdu klínové překážky. Pneumatika vozidla je modelována jako pneumatická pružina s nelineární charakteristikou a s nenulovým koeficientem tlumení. Systém obsahuje dvojčinný hydraulický tlumič. Závěs kola vozidla tvoří dvě vahadla paralelogramu, mechanická šroubová pružina, dvojčinný hydraulický tlumič a kolo s pneumatikou. Je porovnán vliv použití jednočinného a dvojčinného hydraulického tlumiče a vliv rychlosti jízdy na průběh kmitání karoserie nad kolem.Článek Otevřený přístup peer-reviewedpublished UWB radar multipath propagation effects(Univerzita Pardubice, 2006) Čermák, DušanThe paper is dealing with the UWB technology in the radar technique and communications. Special attention is given to the multipath effects in the time domain signal representation, which should be considered for the UWB systems. This is the case when both direct and (multiply) reflected signals are received. The reflections are due to ground, wall and nearby objects. A program was created to model this multipath propagation. The inverse Fourier transform (IFFT) to analyze the signal responses in the time domain was also used and the delay between direct and reflected signals was shown. It is concluded that multiple reflections and multipath effects are much smaller for UWB signals than for CW narrow-band applications as interference minima and maxima do not occur for the same frequencies.Článek Otevřený přístup peer-reviewedpublished K problematice plastických přetvoření povrchových vrstev železničního kola(Univerzita Pardubice, 2006) Beneš, Libor; Schmidová, Eva; Kaloč, RudolfTrvající problémy vzniku poruch v oblasti jízdní plochy železničních kol vyžadují nové přístupy výzkumu zejména v oblasti experimentů, jelikož doposud nelze věrohodně modelovat fyzikální procesy pomocí programových systémů. Tyto děje se odehrávají v povrchových vrstvách kontaktně vázaných těles s rozměrem 10-4 - 10-5 m, kde dochází ke strukturním změnám, včetně vzniku oblastí doposud metalograficky nepopsaných. Pro získání informací, které vedou k modifikaci v současné době akceptovaných mezních stavů je nezbytné realizovat řízený experiment sledující historii kontaktního zatížení. Z dosavadních metalografických sledování lze považovat za prokázané, že prvotně probíhající proces plastických deformací, jehož důsledkem je zpevnění objemů materiálu v kontaktní oblasti, má dominantní vliv na vznik a rozvoj povrchových vad. Jelikož při analýze se nelze opírat o fenomenologické konstanty materiálu, musí numerické modelování selhávat a naopak, experimentální výzkum nelze opírat o konvenční zařízení (např. Amsler). Z uvedených důvodů je na DFJP vyvinuto a realizováno speciální zkušební zařízení, jehož funkce je v příspěvku diskutována.