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Detecting karstic zones during highway construction using ground-penetrating radar
Matevž Uroš Pavlič, Blaž Praznik, 2011, izvirni znanstveni članek

Opis: Ground-penetrating radar (GPR) has been applied to determine the subsurface karstic features during the construction of the national highway in the south-eastern part of Slovenia. The highway construction is situated mostly in the dinaric karstic region with a high density of karstic features visible on the surface. Ground-penetrating radar prospecting was done in all areas where a slope was cut into the limestone bedrock. The main purpose of the survey was to map potentially hazardous zones in the highway subsurface and to detect and characterize the karst. The ground-penetrating radar method was used because of the heterogeneous nature of the karst. With its high degree of karsticifaction and geological diversity all conventional methods failed. One of GPR’s main advantages is that, while the penetration depth is limited to several meters, the obtained resolution can be on the scale of centimeters and the measured profile is continuous. Because of the ground-penetrating radar’s limitations with respect to depth, the range surveying was done simultaneously with the road construction using 200-MHz bistatic antenna on the level of the highway plane. All the 2D radargrams were constructed in 3D models where the measurements were made in raster with 2 meters between a single GPR profile. This two-meters spacing was determined as the optimal value in which only a minimal resolution-price tradeoff was made. The gathered results were tested and compared to experimental drillings and excavations so that any anomalies and reflections were calibrated. The drilling was conducted twice, first to calibrate the radargram reflections and secondly to check and confirm the calibration success. Altogether, over 30 boreholes were drilled at various previously selected locations. The data obtained from the drilling proved to be very helpful with the calibration since anomalies found during the drilling were almost exclusively (over 95%) a result of the propagation of radar waves from the limestone to an air void or from the limestone to a clay pocket. Drilling test boreholes proved to be a very useful tool for the calibration of the GPR anomalies recorded in 2D radargrams. Such a process showed a near 100 % accuracy with respect to interpreting the subsurface features, with 77% correctly interpreted as caves or clay pockets and 23% wrongly interpreted, where the interpretation was a void but it was indeed partly a clay-filled and partly an air-filled void. The completed survey also showed simultaneous surveying with GPR and road construction is a very efficient and economical way to predict various karstic features and the density of the karstic forms.
Ključne besede: karst, ground-penetrating radar, geotechnics, cavities, detection
Objavljeno: 13.06.2018; Ogledov: 558; Prenosov: 66
.pdf Celotno besedilo (756,55 KB)
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A wearable device and system for movement and biometric data acquisition for sports applications
Marko Kos, Iztok Kramberger, 2017, izvirni znanstveni članek

Opis: This paper presents a miniature wearable device and a system for detecting and recording the movement and biometric information of a user during sport activities. The wearable device is designed to be worn on a wrist and can monitor skin temperature and pulse rate. Furthermore, it can monitor arm movement and detect gestures using inertial measurement unit. The device can be used for various professional and amateur sport applications and for health monitoring. Because of its small size and minimum weight, it is especially appropriate for swing-based sports like tennis or golf, where any additional weight on the arms would most likely disturb the player and have some influence on the player’s performance. Basic signal processing is performed directly on the wearable device but for more complex signal analysis, the data can be uploaded via the Internet to a cloud service, where it can be processed by a dedicated application. The device is powered by a lightweight miniature LiPo battery and has about 6 h of autonomy at maximum performance.
Ključne besede: biometric data acquisition, inertial sensing, movement detection, pulse rate, sensor fusion, wearable
Objavljeno: 03.08.2017; Ogledov: 704; Prenosov: 327
.pdf Celotno besedilo (8,88 MB)
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Toward the discovery of citation cartels in citation networks
Iztok Fister, Iztok Fister, Matjaž Perc, 2016, izvirni znanstveni članek

Opis: In this perspective, our goal is to present and elucidate a thus far largely overlooked problem that is arising in scientific publishing, namely the identification and discovery of citation cartels in citation networks. Taking from the well-known definition of a community in the realm of network science, namely that people within a community share significantly more links with each other as they do outside of this community, we propose that citation cartels are defined as groups of authors that cite each other disproportionately more than they do other groups of authors that work on the same subject. Evidently, the identification of citation cartels is somewhat different, although similar to the identification of communities in networks. We systematically expose the problem, provide theoretical examples, and outline an algorithmic guide on how to approach the subject.
Ključne besede: citation network, citation cartel, network science, community detection, cooperation
Objavljeno: 10.07.2017; Ogledov: 1096; Prenosov: 294
.pdf Celotno besedilo (855,89 KB)
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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: 857; Prenosov: 304
.pdf Celotno besedilo (2,36 MB)
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Novel Concepts for the Detection of Microplastics
Jan Ornik, 2016, magistrsko delo

Opis: Microplastics are small pieces of plastic (smaller than 5 mm), which can be found in the environment and can be dangerous to living beings. It is expected that the abundance of microplastics will rise in the future. However, there are still no standard protocols for monitoring the microplastic abundance, which should include spectroscopic methods for an automated discrimination in order to produce reliable data. In this work we examined a new approach for microplastic detection based on the photoluminescence (PL) spectroscopy. To test the applicability of the proposed method a low-cost setup was built and characterized. The PL spectra from 27 different materials were collected and compared. The comparison of the spectra shows that the differentiation between samples is possible, especially between the plastic and non-plastic materials. Furthermore, the measured PL spectra also differ for different plastic types and other materials. However, the presence of dyes in plastic samples and incrustation of plastic samples by organic materials can affect the PL spectra and make the recognition troublesome. Disregarding organic materials and dyed plastic, the material differentiation based on the acquired PL spectra using neural networks resulted in 99.3 % accuracy when categorizing samples into plastic and non-plastic materials and 63.1 % accuracy when categorizing samples among different plastic and non-plastic materials. The promising results show that the PL spectroscopy of microplastics could outperform the spectroscopic methods used so far, by means of measurement speed and lateral resolution.
Ključne besede: microplastics, detection methods, photoluminescence spectroscopy, neural networks
Objavljeno: 10.08.2016; Ogledov: 1237; Prenosov: 123
.pdf Celotno besedilo (2,59 MB)

Unobtrusive heartbeat monitoring by using a bed fiber-optic sensor
Peter Podbreznik, Denis Đonlagić, Dejan Lešnik, Boris Cigale, Damjan Zazula, 2014, izvirni znanstveni članek

Opis: Demographic trends suggest that by 2050 approximately 11 % of the world population will be 80 or older. If a fast increase of chronic diseases is also considered, it becomes clear the present healthcare capacities won't be enough. The elderly and people with limited abilities must be assisted in their home environment and, thus, reduce needs for hospitalization and institutionalization. Today's computer and communication technologies provide different smart devices, which is a core of emerging intensification of homecare services, in particular remote and unobtrusive monitoring of human functional- health parameters.
Ključne besede: plastic optical fiber, speckle interferometry, unobtrusive monitoring of human vital signs, heartbeat detection, ballistocardiography
Objavljeno: 21.12.2015; Ogledov: 893; Prenosov: 88
.pdf Celotno besedilo (573,53 KB)
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Fault detection of an industrial heat-exchanger
Dejan Dragan, 2011, izvirni znanstveni članek

Opis: One of the key issues in modelling for fault detection is how to accommodate the level of detail of the model description in order to suit the diagnostic requirements. The paper addresses a two-stage modelling concept to an industrial heat exchanger, which is located in a tyre factory. Modelling relies on combination of prior knowledge and recorded data. During the identification procedure, the estimates of continuous model parameters are calculated by the least squares method and the state variable filters (SVF). It is shown that the estimates are largely invariant of the bandwidth of the SVFs. This greatly reduces the overall modelling effort and makes the whole concept applicable even to less experienced users. The main issues of the modelling procedure are stressed. Based on the process model a simple detection system is derived. An excerpt of the results obtained on operating records is given.
Ključne besede: industrijski prenosniki toplote, zaznavanje napak, nadzor procesov, odkrivanje napak na osnovi modela, modeliranje, identifikacija, industrial heat exchanger, fault detection, condition monitoring, model-based detection, modelling, identification
Objavljeno: 10.07.2015; Ogledov: 1130; Prenosov: 12
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Unobtrusive monitoring of human vital functions based on speckle interferometry with plastic optical fiber
Peter Podbreznik, Denis Đonlagić, Dejan Lešnik, Boris Cigale, Damjan Zazula, 2013, izvirni znanstveni članek

Opis: In this paper, a speckle interferometer with a plastic optical fiber system is reported for unobtrusive monitoring of heartbeat and respiration. The sensor consists of a laser diode butt-coupled to the plastic optical fiber, whose exit face projects speckle patterns onto a linear optical sensor array, which leads to a simple and cost-effective construction. Speckle images are acquired in a sequence and transformed into a 1D signal by using a phase-shifting method. Band-pass filtering and Morlet-wavelet-based multiresolutional approaches were used to analyze signals for the detection of cardiac and respiratory activities, respectively. Ten young, healthy persons participated in system testing, by lying supine on a mattress with embedded plastic optical fiber. Experimental results show the proposed system and detection algorithms are highly efficient. Sensitivities of 99.4 0.6% and 95.3 3%, precisions of 98.8 1.5% and 97.9 2.3%, and mean delays between interferometric detections and corresponding referential signals of 116.6 55.5ms and 1299.2 437.3 ms were computed for heartbeat and respiration, respectively.
Ključne besede: plastic optical fiber, speckle interferometry, unobtrusive monitoring, heartbeat detection, respiration detection, phase-shift method, wavelet transform
Objavljeno: 10.07.2015; Ogledov: 937; Prenosov: 12
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Fast convex layers algorithm for near-duplicate image detection
Smiljan Šinjur, Damjan Zazula, Borut Žalik, 2012, izvirni znanstveni članek

Opis: This paper builds on a novel, fast algorithm for generating the convex layers on grid points with linear time complexity. Convex layers are extracted from the binary image. The obtained convex hulls are characterized by the number oftheir vertices and used as representative image features. A computational geometric approach to near-duplicate image detection stems from these features. Similarity of feature vectors of given images is assessed by correlation coefficient. This way, all images with closely related structure and contents can be retrieved from large databases of images quickly and efficiently. The algorithm can be used in various applications such as video surveillance, image and video duplication search, or image alignment. Our approach is rather robust up to moderate signal-to-noise ratios, tolerates lossy image compression, and copes with translated, rotated and scaled image contents.
Ključne besede: near duplicate image detection, feature extraction, geometric features, convex layers, similarity measure
Objavljeno: 10.07.2015; Ogledov: 733; Prenosov: 53
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