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21.
Using neural networks in the process of calibrating the microsimulation models in the analysis and design of roundabouts in urban areas
Irena Ištoka Otković, 2011, doktorska disertacija

Opis: The thesis researches the application of neural networks in computer program calibration of traffic micro-simulation models. The calibration process is designed on the basis of the VISSIM micro-simulation model of local urban roundabouts. From the five analyzed methods of computer program calibration, Methods I, II and V were selected for a more detailed research. The three chosen calibration methods varied the number of outgoing traffic indicators predicted by neural networks and a number of neural networks in the computer program calibration procedure. Within the calibration program, the task of neural networks was to predict the output of VISSIM simulations for selected functional traffic parameters - traveling time between the measurement points and queue parameters (maximum queue and number of stopping at the roundabout entrance). The Databases for neural network training consisted of 1379 combinations of input parameters whereas the number of output indicators of VISSIM simulations was varied. The neural networks (176 of them) were trained and compared for the calibration process according to training and generalization criteria. The best neural network for each calibration method was chosen by using the two-phase validation of neural networks. The Method I is the calibration method based on calibration of a traffic indicator -traveling time and it enables validation related to the second observed indicator – queue parameters. Methods II and V connect the previously described calibration and validation procedures in one calibration process which calibrates input parameters according to two traffic indicators. Validation of the analyzed calibration methods was performed on three new sets of measured data - two sets at the same roundabout and one set on another location. The best results in validation of computer program calibration were achieved by the Method I which is the recommended method for computer program calibration. The modeling results of selected traffic parameters obtained by calibrated VISSIM traffic model were compared with: values obtained by measurements in the field, the existing analysis methods of operational roundabouts characteristics (Lausanne method, Kimber-Hollis, HCM) and modeling by the uncalibrated VISSIM model. The calibrated model shows good correspondence with measured values in real traffic conditions. The efficiency of the calibration process was confirmed by comparing the measured and modeled values of delays, of an independent traffic indicator that was not used in the process of calibration and validation of traffic micro-simulation models. There is also an example of using the calibrated model in the impact analysis of pedestrian flows on conflicting input and output flows of vehicles in the roundabout. Different traffic scenarios were analyzed in the real and anticipated traffic conditions.
Ključne besede: traffic models, traffic micro-simulation, calibration of the VISSIM model, computer program calibration method, neural networks in the calibration process, micro-simulation of roundabouts, traffic modeling parameters, driving time, queue parameters, delay
Objavljeno: 02.06.2011; Ogledov: 3149; Prenosov: 214
.pdf Celotno besedilo (13,21 MB)

22.
The complexity of porous structure of building materials
Marko Samec, 2011, doktorska disertacija

Opis: This thesis seeks to establish the link between the structure (in a topological sense) of porous space and charged particle dynamics in porous matter, specifically in constituent elements of sustainable building materials such as clay, cement and soil. The work done is a combination of experimental research and modelling of analysed data using advanced and expanded network models to model pore structure and generalized conductivity model. The main outcome of this doctoral thesis is the demonstration that there is a correlation between the large scale structure of the pore space and the properties of the motion of charged particles through the pore space. This was achieved by conducting two experiments: the structure of pore space of selected porous materials (soil samples, clays, cements, clay-cement mixtures) was investigated using state-of-the-art X-ray computed microtomography, while the dynamics of charged particles in the samples was probed using low-frequency dielectric spectroscopy. The research done and described in the thesis is directed towards the advancement of understanding the transport phenomena and the structure of porous media which is of paramount importance for solving problems in building physics dealing with moist transport in building's envelope, the building-ground interaction, and in transport of contaminants in the vicinity of the repositories where the transfer of moist through soil can be the source of contamination.
Ključne besede: porous matter, clay-water system, hydrating cement, fractional dynamics, dielectric response, X-ray computed tomography, image analysis, complex network
Objavljeno: 11.05.2011; Ogledov: 3142; Prenosov: 118
.pdf Celotno besedilo (34,69 MB)

23.
Numerično modeliranje vpliva veznih sredstev na horizontalno nosilnost lesenih okvirnih stenskih elementov
Milan Kuhta, 2010, doktorska disertacija

Opis: Disertacija obravnava vpliv togosti veznih sredstev in vpliv obložnih plošč na nosilnost lesenih okvirnih stenskih elementov pod vplivom horizontalne sile. Okvirni stenski element predstavlja sovprežno konstrukcijo sestavljeno iz lesenega okvirja in obložnih plošč, ki so na okvir pritrjene z mehanskimi veznimi sredstvi - sponkami. Vpliv sponk smo raziskovali z različnimi razdaljami med sponkami in sicer na preizkušancih z razdaljo med sponkami s=3,75 cm, s=7,50 cm in s=15,00 cm. Vpliv obložnih plošč smo raziskovali z različnimi vrstami obložnih plošč in sicer z enojno mavčno - vlakneno oblogo, z dvojno mavčno - vlakneno oblogo in z oblogo z usmerjenim iverjem. Raziskave smo izvedli eksperimentalno, analitično in numerično (MKE). Analitični in še posebej rezultati numeričnega MKE modela se dobro ujemajo z eksperimentalnimi meritvami. Razdalje med sponkami in različne vrste obložni plošč imajo pomemben vpliv na raziskovano silo ob pojavu prve razpoke obložne plošče, silo porušitve, pomik konzolnega dela panelne stene in na zdrs v nateznem in tlačnem območju priključne ravnine med lesenim okvirjem in obložno ploščo, kakor tudi na upogibno in strižno togost panelnih sten.
Ključne besede: gradbeništvo, mehanika, sovprežne konstrukcije, leseni okvirni stenski elementi, mavčno vlaknaste plošče, plošče z usmerjenim iverjem, vezna sredstva, eksperiment, modeliranje, metoda končnih elementov
Objavljeno: 05.10.2010; Ogledov: 3557; Prenosov: 219
.pdf Celotno besedilo (7,46 MB)

24.
SINTEZA KONSTRUKCIJE JEKLENIH HAL Z MEŠANIM CELOŠTEVILSKIM NELINEARNIM PROGRAMIRANJEM
Tomaž Žula, 2009, doktorska disertacija

Opis: V doktorski disertaciji predstavljamo celovit pristop k sočasnemu optimiranju mase, topologije, diskretnih materialov in standardnih prerezov konstrukcije jeklenih hal. Optimiranje bomo izvedli z mešanim celoštevilskim nelinearnim programiranjem (MINLP). Ker z MINLP izvajamo optimiranje topologije in standardnih dimenzij na način, da se v optimizacijskem procesu posamezni konstrukcijski elementi računsko odvzamejo in/ali dodajajo, izračunavajo pa se tudi standardni materiali, dimenzije in oblika konstrukcije, z MINLP v bistvu izvajamo sintezo konstrukcij. V doktorski disertaciji tako obravnavamo sintezo realnih inženirskih konstrukcij jeklenih hal velikega obsega.
Ključne besede: gradbeništvo, mehanika, konstrukcija, sinteza, sinteza konstrukcij, optimiranje, optimiranje konstrukcij, optimiranje topologije, diskretno optimiranje, mešano celoštevilsko nelinearno programiranje, MINLP, algoritem zunanje aproksimacije s sprostitvijo enačb, OA/ER algoritem, modofocirani algoritem OA/ER, trifazana MINLP strategija, jeklene hale
Objavljeno: 27.05.2010; Ogledov: 3550; Prenosov: 223
.pdf Celotno besedilo (854,43 KB)

25.
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