41. Določitev karakterističnih notranjih statičnih količin cestnih mostov iz podatkov tehtanja vozil med vožnjoAleš Žnidarič, Goran Turk, Maja Kreslin, 2022, izvirni znanstveni članek Povzetek: Prispevek obravnava določitev notranjih statičnih količin cestnih mostov iz podatkov tehtanj vozil med vožnjo (meritev WIM, ang. weigh-in-motion), ki edina zagotovijo celovito in nepristransko sliko o tovornem prometu na merjenem cestnem odseku. Tovrstni podatki so ključni za določitev realnih učinkov prometnih obtežb, s katerimi dokazujemo zadostno varnost mostov, tudi starih in poškodovanih. Takšne mostove bi bilo treba ob upoštevanju obtežnih shem iz sodobnih pravilnikov za mostove pogo- sto zapreti ali jim omejiti prometno obtežbo. Predstavljene so metode, s katerimi iz podatkov WIM izračunamo karakteristične vrednosti notranjih statičnih količin. Posebej smo analizirali metodo konvolucije in rezultate primerjali z rezultati ekstrapolacije ekstremnih vrednosti, najbolj pogostega postopka za napovedovanje maksimalnih pričakovanih vplivov prometa v izbranem obdobju, ter rezultati obsežnih numeričnih simulacij. Veliko pozornost smo namenili izbiri vhodnih parametrov ter načinu od- čitavanja karakterističnih vrednosti, ki bistveno vplivajo na rezultate ekstrapolacij in simulacij. Rezultati kažejo, da daje metoda konvolucije, ki je računsko neprimerno manj zahtevna od ostalih uporabljanih metod, primerljive rezultate. Sočasno so le-ti manj občutljivi za subjektivno izbiro uporabljenih parametrov. Bistveni zaključek analize je tudi, da za zanesljiv račun karakte- rističnih notranjih statičnih količin mostov zaradi prometa potrebujemo s sistemom WIM izmerjene osne pritiske in medosne razdalje vsaj 100.000 tovornih vozil.
Ključne besede: most, tehtanje vozil med vožnjo, notranje statične količine, konvolucija, simulacija, WIM, B-WIM
Objavljeno v DiRROS: 04.12.2023; Ogledov: 298; Prenosov: 107
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42. Smernice za zagotavljanje gozdnega reprodukcijskega materiala : predlog pripravljen v okviru projekta LIFEGENMONKristina Sever, Boris Rantaša, Marijana Vidrih Minić, Natalija Dovč, Janez Kermavnar, Marjana Westergren, Gregor Božič, Matjaž Guček, Andrej Breznikar, Aleš Poljanec, Hojka Kraigher, 2021, elaborat, predštudija, študija Ključne besede: gozdni reprodukcijski material, gozdni semenski objekti, provenienčna območja, vrste, genetska pestrost
Objavljeno v DiRROS: 14.11.2023; Ogledov: 498; Prenosov: 148
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46. Hierarchical learning of robotic contact policiesMihael Simonič, Aleš Ude, Bojan Nemec, 2023, izvirni znanstveni članek Povzetek: The paper addresses the issue of learning tasks where a robot maintains permanent contact with the environment. We propose a new methodology based on a hierarchical learning scheme coupled with task representation through directed graphs. These graphs are constituted of nodes and branches that correspond to the states and robotic actions, respectively. The upper level of the hierarchy essentially operates as a decision-making algorithm. It leverages reinforcement learning (RL) techniques to facilitate optimal decision-making. The actions are generated by a constraint-space following (CSF) controller that autonomously identifies feasible directions for motion. The controller generates robot motion by adjusting its stiffness in the direction defined by the Frenet–Serret frame, which is aligned with the robot path. The proposed framework was experimentally verified through a series of challenging robotic tasks such as maze learning, door opening, learning to shift the manual car gear, and learning car license plate light assembly by disassembly.
Ključne besede: autonomous robot learning, learning, experience, compliance and impedance contro
Objavljeno v DiRROS: 21.09.2023; Ogledov: 462; Prenosov: 251
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47. Neuromuscular assessment of force development, postural, and gait performance under cognitive-motor dual-tasking in healthy older adults and early Parkinson's disease patients : study protocol for a cross-sectional Mobile Brain/Body Imaging (MoBI) studyUroš Marušič, Manca Peskar, Maja Maša Šömen, Miloš Kalc, Aleš Holobar, Klaus Gramann, Bettina Wollesen, Anna Wunderlich, Christoph M. Michel, Aleksandar Miladinović, Mauro Catalan, Alex B. Stella, Miloš Ajčević, Paolo Manganotti, 2023, izvirni znanstveni članek Povzetek: Background: Neuromuscular dysfunction is common in older adults and more pronounced in neurodegenerative diseases. In Parkinson's disease (PD), a complex set of factors often prevents the effective performance of activities of daily living that require intact and simultaneous performance of the motor and cognitive tasks. Methods: The cross-sectional study includes a multifactorial mixed-measure design. Between-subject factor grouping the sample will be Parkinson’s Disease (early PD vs. healthy). The within-subject factors will be the task complexity (single- vs. dual-task) in each motor activity, i.e., overground walking, semi-tandem stance, and isometric knee extension, and a walking condition (wide vs. narrow lane) will be implemented for the overground walking activity only. To study dual-task (DT) effects, in each motor activity participants will be given a secondary cognitive task, i.e., a visual discrimination task for the overground walking, an attention task for the semi-tandem, and mental arithmetic for the isometric extension. Analyses of DT effects and underlying neuronal correlates will focus on both gait and cognitive performance where applicable. Based on an a priori sample size calculation, a total N = 42 older adults (55-75 years) will be recruited. Disease-specific changes such as laterality in motor unit behavior and cortical control of movement will be studied with high-density surface electromyography and electroencephalography during static and dynamic motor activities, together with whole-body kinematics. Discussion: This study will be one of the first to holistically address early PD neurophysiological and neuromuscular patterns in an ecologically valid environment under cognitive-motor DT conditions of different complexities. The outcomes of the study aim to identify the biomarker for early PD either at the electrophysiological, muscular or kinematic level or in the communication between these systems.
Ključne besede: Parkinson's disease, mobile brain imaging, body brain imaging, MoBi, dual tasking, neuromuscular function, older adults
Objavljeno v DiRROS: 15.09.2023; Ogledov: 409; Prenosov: 185
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48. Investigations of 6-pane glazing : properties and possibilitiesAleš Kralj, Marija Drev, Matjaž Žnidaršič, Boštjan Černe, Jože Hafner, Bjørn Petter Jelle, 2019, izvirni znanstveni članek Povzetek: Today there is increasing interest and demand for energy savings in the building sector. Windows still represent a weak point in the building envelope with respect to thermal performance due to thermal losses from the interior to the exterior as well as overheating of the interior due to excessive solar radiation from the exterior environment into the interior. However, windows and glazing structures enable the utilisation of daylight and heat from incident solar radiation, while at the same time providing comfort and a view to the outdoor surroundings. Multipane glazing and windows may represent a possible way to lower energy consumption related to heating and cooling. In this study, a multipane glazing structure, more specifically a 6-pane glazing, has been constructed and investigated with regard to various properties and possibilities. The general configuration of the 6-pane glazing is described. Furthermore, properties such as U-value, solar energy transmittance, visible transmittance, solar heat gain coefficient, glass pane temperatures, vapour permeability, economical aspects, and comfort of living, among others, are analysed. Finally, a case study is presented that demonstrates a 50% reduction in the annual energy consumption after renovation with this 6-pane glazing.
Ključne besede: window, multipane glazing, building, U-value, solar transmittance, temperature
Objavljeno v DiRROS: 14.09.2023; Ogledov: 351; Prenosov: 158
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49. Using statistical analysis of an acceleration-based bridge weigh-in-motion system for damage detectionEugene J. O'Brien, Muhammad Arslan Khan, Daniel Patrick McCrum, Aleš Žnidarič, 2020, izvirni znanstveni članek Povzetek: This paper develops a novel method of bridge damage detection using statistical analysis of data from an acceleration-based bridge weigh-in-motion (BWIM) system. Bridge dynamic analysis using a vehicle-bridge interaction model is carried out to obtain bridge accelerations, and the BWIM concept is applied to infer the vehicle axle weights. A large volume of traffic data tends to remain consistent (e.g., most frequent gross vehicle weight (GVW) of 3-axle trucks); therefore, the statistical properties of inferred vehicle weights are used to develop a bridge damage detection technique. Global change of bridge stiffness due to a change in the elastic modulus of concrete is used as a proxy of bridge damage. This approach has the advantage of overcoming the variability in acceleration signals due to the wide variety of source excitations/vehicles–data from a large number of different vehicles can be easily combined in the form of inferred vehicle weight. One year of experimental data from a short-span reinforced concrete bridge in Slovenia is used to assess the effectiveness of the new approach. Although the acceleration-based BWIM system is inaccurate for finding vehicle axle-weights, it is found to be effective in detecting damage using statistical analysis. It is shown through simulation as well as by experimental analysis that a significant change in the statistical properties of the inferred BWIM data results from changes in the bridge condition.
Ključne besede: bridge health monitoring, bridge WIM, structural dynamics, damage detection, vehicle-bridge interaction
Objavljeno v DiRROS: 12.09.2023; Ogledov: 414; Prenosov: 167
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50. Using bridge weigh-in-motion systems to monitor single-span bridge influence linesAleš Žnidarič, Jan Kalin, 2020, izvirni znanstveni članek Povzetek: Bridge weigh-in-motion systems use instrumented bridges or culverts to weigh vehicles as they pass over the structures. They also provide data to allow the calculation of several bridge performance indicators. The article starts with the basics of a bridge weigh-in-motion system and briefly describes two key bridge performance indicators, girder distribution factor and dynamic amplification factor, which are also derived from B-WIM measurements. The central part of the article focuses on monitoring of influence lines, the third key parameter that characterises the bridge performance under traffic loads. First, the method of calculating the bending moment influence lines from random heavy traffic is described. A coefficient of rotational stiffness is introduced, which defines the shape of influence lines around the supports as a linear combination of the ideal simply supported and fixed supported influence lines, to allow quantifying the influence line changes. Then the long-term monitoring of influence lines is investigated on four different single-span test bridges. The initial focus is given on the examination of the effect of temperature on the shape of influence lines. Finally, two sets of influence lines are compared on one test bridge, one from before and the other from after replacing the expansion joints and bearings. The work done so far confirms that calculating of influence lines from random vehicles with a B-WIM system is entirely feasible and that differences in their shape can be detected on single-span bridges. What remains to be investigated is the comparison of these differences to the actual damages and under which circumstances the proposed procedure can compete with or better the routine bridge inspection and the conventional monitoring techniques.
Ključne besede: bridge loading, bridge response, temperature dependency, influence line, monitoring
Objavljeno v DiRROS: 12.09.2023; Ogledov: 456; Prenosov: 167
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