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A DSL for the development of software agents working within a semantic web environment
Sebla Demirkol, Moharram Challenger, Sinem Getir, Tomaž Kosar, Geylani Kardas, Marjan Mernik, 2013, izvirni znanstveni članek

Opis: Software agents became popular in the development of complex software systems,especially those requiring autonomous and proactive behavior. Agents interact with each other within a Multi-agent System (MAS), in order to perform certain defined tasks in a collaborative and/or selfish manner. However, the autonomous, proactive and interactive structure of MAS causes difficulties when developing such software systems. It is within this context,that the use of a Domain-specific Language (DSL) may support easier and quicker MAS development methodology. The impact of such DSL usage could beclearer when considering the development of MASs, especially those working on new challenging environments like the Semantic Web. Hence, this paper introduces a new DSL for Semantic Web enabled MASs. This new DSL is called Semantic web Enabled Agent Language (SEA_L). Both the SEA_L user-aspects and the way of implementing SEA_L are discussed in the paper. The practical use of SEA_L is also demonstrated using a case study which considers the modeling of a multi-agent based e-barter system. When considering the language implementation, we first discuss the syntax of SEA_L and we show how the specifications of SEA_L can be utilized during the code generation of real MAS implementations. The syntax of SEA_L is supported by textual modeling toolkits developed with Xtext. Code generation for the instance models are supplied with the Xpand tool.
Ključne besede: domain-specific language, DSL, metamodel, multi-agent system, semantic web
Objavljeno: 06.07.2017; Ogledov: 42; Prenosov: 3
.pdf Celotno besedilo (458,07 KB)

Assessment of magnetic fluid losses out of magnetic properties measurement
Miloš Beković, Irena Ban, Anton Hamler, 2010, objavljeni znanstveni prispevek na konferenci

Opis: In this paper an improved measurement system for experimental assessment of magnetic fluid losses is presented. When fluid is exposed to AC magnetic field, three different losses mechanisms are active; relaxation, hysteresis and resonance mechanism. In this paper not individual contributions where studied but combine acting which can be determine as specific power losses (SPL). SPL of the sample is obtained for a variety of amplitudes and frequencies of magnetic field with presented method of measurement of field parameters where results revealed f H2 dependence for fixed temperature of the sample. Temperature dependence of SPL is examined with calorimetrical measurements, where heating of magnetic fluid at fixed value of applied field and various frequencies is examined and results revealed linearly decreasing temperature dependence.
Ključne besede: magnetic fluid loss, magentic field, hysteresis loop
Objavljeno: 30.06.2017; Ogledov: 51; Prenosov: 4
.pdf Celotno besedilo (495,15 KB)

An innovative approach to near-infrared spectroscopy using a standard mobile device and its clinical application in the real-time visualization of peripheral veins
Simon Jurič, Borut Žalik, 2014, izvirni znanstveni članek

Opis: Background: Excessive venipunctures are a significant problem both in emergency rooms and during hospital stays. Near-infrared (NIR) illumination devices improve venipuncture success rate but their usage is limited by their availability and economic cost. The objectives of this study were to develop a low-cost NIR spectroscopy prototype from a standard mobile device, to evaluate its efficacy and acceptance as an educational tool, and in a clinical setting. Methods: Through a user-centric design process a prototype device was developed. Its educational efficacy was evaluated through a non-invasive, observational study (20 student clinicians, 25 subjects) and its acceptance was assessed using quantitative and qualitative analysis. A smaller clinical trial was performed by a group of 4 medical professionals over a period of 6 weeks that involved 64 patients. Results: The prototype enables real-time visualization of peripheral veins on a variety of Android-based devices. The prototype was 35.2% more successful in visualizing and locating veins (n = 500 attempts) than the nursing students. The acceptance assessment revealed high perception of usefulness, satisfaction, and ease of use. In the clinical trial, 1.6 (SD 1.3) additional veins per patient were identified compared with the traditional visualization methods. Conclusions: To the best of our knowledge this is the first study that describes the design, feasibility and application of an NIR spectroscopy prototype developed on a standard mobile device.
Ključne besede: mobile applications, spectroscopy, near-infrared, NIRS, vascular access devices, health education, feasibility
Objavljeno: 29.06.2017; Ogledov: 53; Prenosov: 5
.pdf Celotno besedilo (2,32 MB)

A biometric authentication model using hand gesture images
Simon Fong, Yan Zhuang, Iztok Fister, Iztok Fister, 2013, izvirni znanstveni članek

Opis: A novel hand biometric authentication method based on measurements of the user's stationary hand gesture of hand sign language is proposed. The measurement of hand gestures could be sequentially acquired by a low-cost video camera. There could possibly be another level of contextual information,associated with these hand signs to be used in biometric authentication. As an analogue, instead of typing a password 'iloveu' in text which is relatively vulnerable over a communication network, a signer can encode a biometric password using a sequence of hand signs, 'i', 'l', 'o', 'v', 'e', and 'u'. Subsequently the features from the hand gesture images are extracted which are integrally fuzzy in nature, to be recognized by a classification model for telling if this signer is who he claimed himself to be, by examining over his hand shape and the postures in doing those signs. Itis believed that everybody has certain slight but unique behavioral characteristics in sign language, so are the different hand shape compositions. Simple and efficient image processing algorithms are used in hand sign recognition, including intensity profiling, color histogram and dimensionality analysis, coupled with several popular machine learning algorithms. Computer simulation is conducted for investigating the efficacy ofthis novel biometric authentication model which shows up to 93.75% recognition accuracy.
Ključne besede: biometric authentication, hand gesture, hand sign recognition, machine learning
Objavljeno: 28.06.2017; Ogledov: 74; Prenosov: 5
.pdf Celotno besedilo (1,83 MB)

Context-dependent factored language models
Gregor Donaj, Zdravko Kačič, 2017, izvirni znanstveni članek

Opis: The incorporation of grammatical information into speech recognition systems is often used to increase performance in morphologically rich languages. However, this introduces demands for sufficiently large training corpora and proper methods of using the additional information. In this paper, we present a method for building factored language models that use data obtained by morphosyntactic tagging. The models use only relevant factors that help to increase performance and ignore data from other factors, thus also reducing the need for large morphosyntactically tagged training corpora. Which data is relevant is determined at run-time, based on the current text segment being estimated, i.e., the context. We show that using a context-dependent model in a two-pass recognition algorithm, the overall speech recognition accuracy in a Broadcast News application improved by 1.73% relatively, while simpler models using the same data achieved only 0.07% improvement. We also present a more detailed error analysis based on lexical features, comparing first-pass and second-pass results.
Ključne besede: speech recognition, factored language model, dynamic backoff path, word context, inflectional language, morphosyntactic tags
Objavljeno: 26.06.2017; Ogledov: 119; Prenosov: 5
.pdf Celotno besedilo (1,17 MB)

Online speech/music segmentation based on the variance mean of filter bank energy
Marko Kos, Matej Grašič, Zdravko Kačič, 2009, izvirni znanstveni članek

Opis: This paper presents a novel feature for online speech/music segmentation basedon the variance mean of filter bank energy (VMFBE). The idea that encouraged the feature's construction is energy variation in a narrow frequency sub-band. The energy varies more rapidly, and to a greater extent for speech than for music. Therefore, an energy variance in such a sub-band isgreater for speech than for music. The radio broadcast database and the BNSIbroadcast news database were used for feature discrimination and segmentation ability evaluation. The calculation procedure of the VMFBE feature has 4 out of 6 steps in common with the MFCC feature calculation procedure. Therefore, it is a very convenient speech/music discriminator for use in real-time automatic speech recognition systems based on MFCC features, because valuable processing time can be saved, and computation load is only slightly increased. Analysis of the feature's speech/music discriminative ability shows an average error rate below 10% for radio broadcast material and it outperforms other features used for comparison, by more than 8%. The proposed feature as a stand-alone speech/music discriminator in a segmentation system achieves an overall accuracy of over 94% on radio broadcast material.
Ključne besede: online speech segmentation, algorithm, speech techniques
Objavljeno: 26.06.2017; Ogledov: 87; Prenosov: 3
.pdf Celotno besedilo (1,49 MB)

A comprehensive noise robust speech parameterization algorithm using wavelet packet decomposition-based denoising and speech feature representation techniques
Bojan Kotnik, Zdravko Kačič, 2007, izvirni znanstveni članek

Opis: This paper concerns the problem of automatic speech recognition in noise-intense and adverse environments. The main goal of the proposed work is the definition, implementation, and evaluation of a novel noise robust speech signal parameterization algorithm. The proposed procedure is based on time-frequency speech signal representation using wavelet packet decomposition. A new modified soft thresholding algorithm based on time-frequency adaptive threshold determination was developed to efficiently reduce the level of additive noise in the input noisy speech signal. A two-stage Gaussian mixture model (GMM)-based classifier was developed to perform speech/nonspeech as well as voiced/unvoiced classification. The adaptive topology of the wavelet packet decomposition tree based on voiced/unvoiced detection was introduced to separately analyze voiced and unvoiced segments of the speech signal. The main feature vector consists of a combination of log-root compressed wavelet packet parameters, and autoregressive parameters. The final output feature vector is produced using a two-staged feature vector postprocessing procedure. In the experimental framework, the noisy speech databases Aurora 2 and Aurora 3 were applied together with corresponding standardized acoustical model training/testing procedures. The automatic speech recognition performance achieved using the proposed noise robust speech parameterization procedure was compared to the standardized mel-frequency cepstral coefficient (MFCC) feature extraction procedures ETSI ES 201 108 and ETSI ES 202 050.
Ključne besede: speech parametrization, algorithm, speech techniques
Objavljeno: 26.06.2017; Ogledov: 101; Prenosov: 6
.pdf Celotno besedilo (984,48 KB)

Next generation AT-cut quartz crystal sensing devices
Vojko Matko, 2011, izvirni znanstveni članek

Opis: Generally, AT-cut quartz crystals have a limited scope of use when it comes to high-precision measurement of very small impedance changes due to their nonlinear frequency-temperature characteristics in the range between 0 °C and 50 °C. The new method improving quartz oscillator frequency-temperature characteristic compensation is switching between two impedance loads. By modifying the oscillator circuit with two logic switches and two impedance loads, the oscillator can switch oscillation between two resonance frequencies. The difference in resonance frequencies compensates the frequency-temperature characteristics influence as well as the influence of of fset and quartz crystal ageing. The experimental results show that the new approach using the switching method highly improves second-to-second frequency stability from +/-0.125 Hz to +/-0.00001 Hz and minute-to-minute frequency stability from 0.1 Hz to 0.0001 Hz, which makes the high-precision measurement of aF and fH changes possible.
Ključne besede: quartz crystal, switching oscillating method, temperature characteristic compensation
Objavljeno: 22.06.2017; Ogledov: 102; Prenosov: 6
.pdf Celotno besedilo (382,71 KB)

New quartz oscillator switching method for nano-Henry range inductance measurements
Vojko Matko, Karel Jezernik, 2012, izvirni znanstveni članek

Opis: This article introduces a new method for nano-Henry inductance measurements atthe frequency of 4.999 MHz with a single quartz crystal oscillating in the switching oscillating circuit. The real novelty of this method, however, lies in a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 0 °C and 50 °C through a switching method which compensates for the crystalćs natural temperature characteristics. This allows for the compensation of any influences on the crystal such as the compensation of the non-linear temperature characteristicsand the ageing of both the crystal and other oscillating circuit elements, as well as the reduction of the output frequency measurementerrors with the help of an additional reference frequency. The experimental results show that the switching method greatly improves the measurement of small inductance changes in the range between H and nH, allowing as a result high-precision measurements (~0.35 fH) in this range.
Ključne besede: quartz crystal, switching oscillating method, nano-Henry range measurement
Objavljeno: 22.06.2017; Ogledov: 65; Prenosov: 4
.pdf Celotno besedilo (872,06 KB)

MOS-FET as a current sensor in power electronics converters
Rok Pajer, Miro Milanovič, Miran Rodič, Branko Premzel, 2015, izvirni znanstveni članek

Opis: This paper presents a current sensing principle appropriate for use in power electronics’ converters. This current measurement principle has been developed for metal oxide semiconductor field effect transistor (MOS-FET) and is based on UDS voltage measurement. In practice, shunt resistors and Hall effect sensors are usually used for these purposes, but the presented principle has many advantages. There is no need for additional circuit elements within high current paths, causing parasitic inductances and increased production complexity. The temperature dependence of MOS-FETs conductive resistance RDS−ON is considered in order to achieve the appropriate measurement accuracy. The “MOS-FET sensor” is also accompanied by a signal acquisition electronics circuit with an appropriate frequency bandwidth. The obtained analogue signal is therefore interposed to an A-D converter for further data acquisition. In order to achieve sufficient accuracy, a temperature compensation and appropriate approximation is used (RDS−ON = RDS−ON(Vj)). The MOS-FET sensor is calibrated according to a reference sensor based on the Hall-effect principle. The program algorithm is executed on 32-bit ARM M4 MCU, STM32F407.
Ključne besede: power electronics, converters, MOS-FET, current measurement, thermal model
Objavljeno: 22.06.2017; Ogledov: 94; Prenosov: 9
.pdf Celotno besedilo (1,32 MB)

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