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Reliable and accurate release of micro-sized objects with a gripper that uses the capillary-force method
Suzana Uran, Riko Šafarič, Božidar Bratina, 2017, izvirni znanstveni članek

Opis: There have been recent developments in grippers that are based on capillary force and condensed water droplets. These are used for manipulating micro-sized objects. Recently, one-finger grippers have been produced that are able to reliably grip using the capillary force. To release objects, either the van der Waals, gravitational or inertial-forces method is used. This article presents methods for reliably gripping and releasing micro-objects using the capillary force. The moisture from the surrounding air is condensed into a thin layer of water on the contact surfaces of the objects. From the thin layer of water, a water meniscus between the micro-sized object, the gripper and the releasing surface is created. Consequently, the water meniscus between the object and the releasing surface produces a high enough capillary force to release the micro-sized object from the tip of the one-finger gripper. In this case, either polystyrene, glass beads with diameters between 5–60 µm, or irregularly shaped dust particles of similar sizes were used. 3D structures made up of micro-sized objects could be constructed using this method. This method is reliable for releasing during assembly and also for gripping, when the objects are removed from the top of the 3D structure—the so-called “disassembling gripping” process. The accuracy of the release was lower than 0.5 µm.
Ključne besede: micro-objects, one-finger gripper, gripping, releasing, capillary force
Objavljeno: 21.06.2017; Ogledov: 88; Prenosov: 4
.pdf Celotno besedilo (4,70 MB)

A benchmark of lidar-based single tree detection methods using heterogeneous forest data from the alpine space
Domen Mongus, Milan Kobal, Emanuele Lingua, Norbert Pfeifer, Lothar Eysn, Markus Hollaus, Eva Lindberg, Frédéric Berger, Jean-Matthieu Monnet, Michele Dalponte, Marco Pellegrini, 2015, izvirni znanstveni članek

Opis: In this study, eight airborne laser scanning (ALS)-based single tree detection methods are benchmarked and investigated. The methods were applied to a unique dataset originating from different regions of the Alpine Space covering different study areas, forest types, and structures. This is the first benchmark ever performed for different forests within the Alps. The evaluation of the detection results was carried out in a reproducible way by automatically matching them to precise in situ forest inventory data using a restricted nearest neighbor detection approach. Quantitative statistical parameters such as percentages of correctly matched trees and omission and commission errors are presented. The proposed automated matching procedure presented herein shows an overall accuracy of 97%. Method based analysis, investigations per forest type, and an overall benchmark performance are presented. The best matching rate was obtained for single-layered coniferous forests. Dominated trees were challenging for all methods. The overall performance shows a matching rate of 47%, which is comparable to results of other benchmarks performed in the past. The study provides new insight regarding the potential and limits of tree detection with ALS and underlines some key aspects regarding the choice of method when performing single tree detection for the various forest types encountered in alpine regions.
Ključne besede: single tree extraction, airborne laser scanning, forest inventory, comparative testing, co-registration, mountain forests, Alpine space, matching
Objavljeno: 21.06.2017; Ogledov: 50; Prenosov: 2
.pdf Celotno besedilo (13,97 MB)

Reactivation system for proton-exchange membrane fuel-cells
Carlos Restrepo, Oriol Avino, Javier Calvente, Alfonzo Romero, Miro Milanovič, Roberto Giral, 2012, izvirni znanstveni članek

Opis: In recent years, Proton-Exchange Membrane Fuel Cells (PEMFCs) have been the focus of very intensive researches. Manufacturers of these alternative power sources propose a rejuvenation sequence after the FC has been operating at high power for a certain period of time. These rejuvenation methods could be not appropriate for the reactivation of the FC when it has been out of operation for a long period of time or after it has been repaired. Since the developed reactivation system monitors temperature, current, and the cell voltages of the stack, it could be also useful for the diagnostic and repairing processes. The limited number of published contributions suggests that systems developing reactivation techniques are an open research field. In this paper, an automated system for reactivating PEMFCs and results of experimental testing are presented.
Ključne besede: reactivation system, PEM fuel cell, automated system
Objavljeno: 21.06.2017; Ogledov: 29; Prenosov: 3
.pdf Celotno besedilo (789,13 KB)

Motor unit characteristics after targeted muscle reinnervation
Tamás Kapelner, Ning Jiang, Aleš Holobar, Ivan Vujaklija, Aidan Roche, Dario Farina, Oskar Aszmann, 2016, izvirni znanstveni članek

Opis: Targeted muscle reinnervation (TMR) is a surgical procedure used to redirect nerves originally controlling muscles of the amputated limb into remaining muscles above the amputation, to treat phantom limb pain and facilitate prosthetic control. While this procedure effectively establishes robust prosthetic control, there is little knowledge on the behavior and characteristics of the reinnervated motor units. In this study we compared the m. pectoralis of five TMR patients to nine able-bodied controls with respect to motor unit action potential (MUAP) characteristics. We recorded and decomposed high-density surface EMG signals into individual spike trains of motor unit action potentials. In the TMR patients the MUAP surface area normalized to the electrode grid surface (0.25 ± 0.17 and 0.81 ± 0.46, p < 0.001) and the MUAP duration (10.92 ± 3.89 ms and 14.03 ± 3.91 ms, p < 0.01) were smaller for the TMR group than for the controls. The mean MUAP amplitude (0.19 ± 0.11 mV and 0.14 ± 0.06 mV, p = 0.07) was not significantly different between the two groups. Finally, we observed that MUAP surface representation in TMR generally overlapped, and the surface occupied by motor units corresponding to only one motor task was on average smaller than 12% of the electrode surface. These results suggest that smaller MUAP surface areas in TMR patients do not necessarily facilitate prosthetic control due to a high degree of overlap between these areas, and a neural information—based control could lead to improved performance. Based on the results we also infer that the size of the motor units after reinnervation is influenced by the size of the innervating motor neuron.
Ključne besede: target muscle reinnervation, motor unit, controlling muscles
Objavljeno: 19.06.2017; Ogledov: 53; Prenosov: 4
.pdf Celotno besedilo (1,51 MB)

A comparison of comprehension processes in sign language interpreter videos with or without captions
Ines Kožuh, Matjaž Debevc, Danijela Milošević, 2015, izvirni znanstveni članek

Opis: One important theme in captioning is whether the implementation of captions in individual sign language interpreter videos can positively affect viewers% comprehension when compared with sign language interpreter videos without captions. In our study, an experiment was conducted using four video clips with information about everyday events. Fifty-one deaf and hard of hearing sign language users alternately watched the sign language interpreter videos with, and without, captions. Afterwards, they answered ten questions. The results showed that the presence of captions positively affected their rates of comprehension, which increased by 24% among deaf viewers and 42% among hard of hearing viewers. The most obvious differences in comprehension between watching sign language interpreter videos with and without captions were found for the subjects of hiking and culture, where comprehension was higher when captions were used. The results led to suggestions for the consistent use of captions in sign language interpreter videos in various media.
Ključne besede: sign language, comparison, interpreter videos
Objavljeno: 19.06.2017; Ogledov: 67; Prenosov: 2
.pdf Celotno besedilo (857,94 KB)

Towards the novel reasoning among particles in PSO by the use of RDF and SPARQL
Iztok Fister, Xin-She Yang, Karin Ljubič Fister, Dušan Fister, Janez Brest, Iztok Fister, 2014, izvirni znanstveni članek

Opis: The significant development of the Internet has posed some new challenges and many new programming tools have been developed to address such challenges. Today, semantic web is a modern paradigm for representing and accessing knowledge data on the Internet. This paper tries to use the semantic tools such as resource definition framework (RDF) and RDF query language (SPARQL) for the optimization purpose. These tools are combined with particle swarm optimization (PSO) and the selection of the best solutions depends on its fitness. Instead of the local best solution, a neighborhood of solutions for each particle can be defined and used for the calculation of the new position, based on the key ideas from semantic web domain. The preliminary results by optimizing ten benchmark functions showed the promising results and thus this method should be investigated further.
Ključne besede: resource definition framework, SPARQL, best solutions, RDF, PSO
Objavljeno: 15.06.2017; Ogledov: 77; Prenosov: 4
.pdf Celotno besedilo (1,67 MB)

Towards a low-cost mobile subcutaneous vein detection solution using near-infrared spectroscopy
Simon Jurič, Vojko Flis, Matjaž Debevc, Andreas Holzinger, Borut Žalik, 2014, pregledni znanstveni članek

Opis: Excessive venipunctures are both time- and resource-consuming events, which cause anxiety, pain, and distress in patients, or can lead to severe harmful injuries. We propose a low-cost mobile health solution for subcutaneous vein detection using near-infrared spectroscopy, along with an assessment of the current state of the art in this field. The first objective of this study was to get a deeper overview of the research topic, through the initial team discussions and a detailed literature review (using both academic and grey literature). The second objective, that is, identifying the commercial systems employing near-infrared spectroscopy, was conducted using the PubMed database. The goal of the third objective was to identify and evaluate (using the IEEE Xplore database) the research efforts in the field of low-cost near-infrared imaging in general, as a basis for the conceptual model of the upcoming prototype. Although the reviewed commercial devices have demonstrated usefulness and value for peripheral veins visualization, other evaluated clinical outcomes are less conclusive. Previous studies regarding low-cost near-infrared systems demonstrated the general feasibility of developing cost-effective vein detection systems; however, their limitations are restricting their applicability to clinical practice. Finally, based on the current findings, we outline the future research direction.
Ključne besede: subcutaneous vein detection, diagnostic methods and procedures, infrared rays, spectroscopy, vascular diseases, mobile devices
Objavljeno: 15.06.2017; Ogledov: 75; Prenosov: 2
.pdf Celotno besedilo (2,36 MB)

Optimal robust motion controller design using multi-objective genetic algorithm
Andrej Sarjaš, Rajko Svečko, Amor Chowdhury, 2014, izvirni znanstveni članek

Opis: This paper describes the use of a multi-objective genetic algorithm for robust motion controller design. Motion controller structure is based on a disturbance observer in an RIC framework. The RIC approach is presented in the form with internal and external feedback loops, in which an internal disturbance rejection controller and an external performance controller must be synthesised. This paper involves novel objectives for robustness and performance assessments for such an approach. Objective functions for the robustness property of RIC are based on simple even polynomials with non-negativity conditions. Regional pole placement method is presented with the aims of controllers% structures simplification and their additional arbitrary selection. Regional pole placement involves arbitrary selection of central polynomials for both loops, with additional admissible region of the optimized pole location. Polynomial deviation between selected and optimized polynomials is measured with derived performance objective functions. A multi-objective function is composed of different unrelated criteria such as, robust stability, controllers' stability and time performance indexes of closed loops. The design of controllers and multi-objective optimization procedure involve a set of the objectives, which are optimized simultaneously with a genetic algorithm - Differential evolution.
Ključne besede: disturbance observer, DOB, uncertainty systems, optimal robust control, multi-objective optimization, differential evolution
Objavljeno: 15.06.2017; Ogledov: 72; Prenosov: 2
.pdf Celotno besedilo (2,22 MB)

A novel hybrid self-adaptive bat algorithm
Iztok Fister, Simon Fong, Janez Brest, Iztok Fister, 2014, izvirni znanstveni članek

Opis: Nature-inspired algorithms attract many researchers worldwide for solving the hardest optimization problems. One of the newest members of this extensive family is the bat algorithm. To date,many variants of this algorithm have emerged for solving continuous as well as combinatorial problems. One of the more promising variants, a self-adaptive bat algorithm, has recently been proposed that enables a self-adaptation of its control parameters. In this paper, we have hybridized this algorithmusing differentDE strategies and applied these as a local search heuristics for improving the current best solution directing the swarm of a solution towards the better regions within a search space.The results of exhaustive experiments were promising and have encouraged us to invest more efforts into developing in this direction.
Ključne besede: algorithms, optimization
Objavljeno: 15.06.2017; Ogledov: 93; Prenosov: 3
.pdf Celotno besedilo (1,92 MB)

Progressive fastICA peel-off and convolution kernel compensation demonstrate high agreement for high density surface EMG decomposition
Maoqi Chen, Aleš Holobar, Xu Zhang, Ping Zhou, 2016, izvirni znanstveni članek

Opis: Decomposition of electromyograms (EMG) is a key approach to investigating motor unit plasticity. Various signal processing techniques have been developed for high density surface EMG decomposition, among which the convolution kernel compensation (CKC) has achieved high decomposition yield with extensive validation. Very recently, a progressive FastICA peel-off (PFP) framework has also been developed for high density surface EMG decomposition. In this study, the CKC and PFP methods were independently applied to decompose the same sets of high density surface EMG signals. Across 91 trials of 64-channel surface EMG signals recorded from the first dorsal interosseous (FDI) muscle of 9 neurologically intact subjects, there were a total of 1477 motor units identified from the two methods, including 969 common motor units. On average, 10.6 ± 4.3 common motor units were identified from each trial, which showed a very high matching rate of 97.85 ± 1.85% in their discharge instants. The high degree of agreement of common motor units from the CKC and the PFP processing provides supportive evidence of the decomposition accuracy for both methods. The different motor units obtained from each method also suggest that combination of the two methods may have the potential to further increase the decomposition yield.
Ključne besede: EMG, electromyograms, muscle, convultions
Objavljeno: 15.06.2017; Ogledov: 76; Prenosov: 3
.pdf Celotno besedilo (1,18 MB)

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