Quasi-distributed long-gauge fiber optic sensor systemMatjaž Linec
, Denis Đonlagić
, 2009, original scientific article
Abstract: This paper presents a quasi-distributed, long-gauge, sensor system for measurement optical path length variation. This system can be directly applied to long gauge strain and/or temperature sensing. The proposed sensor system is comprised of sensing fiber, which is divided into the sensorćs segments separated by semi reflective mirrors made out of standard optical connectors. Short duration radio-frequency modulated optical bursts are launched into the sensing fiber and phase differences among individual reflected bursts are measured to determine the optical path-length variations among neighboring mirrors. Twenty sensing fiber segments were successfully addressed by a single-signal processor, while relying on standard telecommunication PIN diode, and a Fabry Perot laser diode. The resolution of a fiber-length variation better than 5 ìm was demonstrated in practice. Since the long sections of fiber can be employed for constructing individual sensors within the sensor's array, a microstrain resolution can be achieved in practice. The drift of the sensorćs system can be predominantly attributed to the temperature sensitivity of the electronic components, which proved to be below 20 um/°C. The entire system relies on simple and widely-used components that are low-cost.
Keywords: fiber optic systems, fiber optics sensors, sensing fiber, long-gauge, strain sensing, temperature sensing, optoelectronics
Published: 31.05.2012; Views: 1042; Downloads: 19
Full text (0,00 KB)
Behaviour of short cracks emanating from tiny drilled holesP. O. Maruščak
, Tomaž Vuherer
, Vladimir Gliha
, 2013, original scientific article
Abstract: Specimens with martensitic microstructure were defected by tiny drilled holes with the existing local residual stresses induced by drilling and without them. The objective of this research was to determine the cyclic stress level for the crack initiation and fatigue limit of the defected and smooth specimens' dependence upon the residual-stress field. Compressive residual stresses retarded the crack initiation. Immediately after the crack initiation, residual stresses decelerated the short-crack propagation, but later, when the residual-stress sign was changed, they accelerated it. Non-propagating short-crack size and fatigue limit also depend on the residual-stress field.
Keywords: small defect, drilled hole, crack initiation, crack propagation, short crack, long crack, anomalous fast-crack propagation
Published: 10.07.2015; Views: 372; Downloads: 20
Full text (1,42 MB)
Testing pronunciation varieties of English in primary school through pictorial and textual inputMejade Tomažič
, 2016, undergraduate thesis
Abstract: We are surrounded with different varieties of English language. We listen to English music or radio shows, watch English movies and shows and watch English videos on the internet. The most common varieties that we encounter are British English and American English, which have distinctive differences in stress and pronunciation. Because we encounter both varieties daily, we have found it interesting to see which one prevails in our primary schools. The British English variety is primarily taught in school and the American variety is all around us and is thus more likely to be acquired. Children acquire a foreign language very easily if they are in contact with it on a regular basis. This is as nowadays, as we all hear English lyrics on the radio or hear English conversations on TV.
The thesis focuses on the factors that might influence the choice of the English variety. It explores if the input, whether it is pictorial with pictures or textual with words, influences the choice of variety. It also presents connections between the pronunciation of more frequent and less frequent words with choice of variety, the influence of the pupils’ backgrounds, and way of learning English.
Keywords: word recognition, working and long-term memory, second language, language acquisition, language learning, British and American English pronunciation.
Published: 15.11.2016; Views: 603; Downloads: 22
Full text (1,13 MB)
Long-term survival in glioblastoma: methyl guanine methyl transferase (MGMT) promoter methylation as independent favourable prognostic factorUroš Smrdel
, Mara Popović
, Matjaž Zwitter
, Emanuela Boštjančič
, Andrej Zupan
, Viljem Kovač
, Damjan Glavač
, Drago Bokal
, Janja Jerebic
, original scientific article
Abstract: Background: In spite of significant improvement after multi-modality treatment, prognosis of most patients with glioblastoma remains poor. Standard clinical prognostic factors (age, gender, extent of surgery and performance status) do not clearly predict long-term survival. The aim of this case-control study was to evaluate immuno-histochemical and genetic characteristics of the tumour as additional prognostic factors in glioblastoma.
Patients and methods: Long-term survivor group were 40 patients with glioblastoma with survival longer than 30 months. Control group were 40 patients with shorter survival and matched to the long-term survivor group according to the clinical prognostic factors. All patients underwent multimodality treatment with surgery, postoperative conformal radiotherapy and temozolomide during and after radiotherapy. Biopsy samples were tested for the methylation of MGMT promoter (with methylation specific polymerase chain reaction), IDH1 (with immunohistochemistry), IDH2, CDKN2A and CDKN2B (with multiplex ligation-dependent probe amplification), and 1p and 19q mutations (with fluorescent in situ hybridization).
Results: Methylation of MGMT promoter was found in 95% and in 36% in the long-term survivor and control groups, respectively (p < 0.001). IDH1 R132H mutated patients had a non-significant lower risk of dying from glioblastoma (p = 0.437), in comparison to patients without this mutation. Other mutations were rare, with no significant difference between the two groups.
Conclusions: Molecular and genetic testing offers additional prognostic and predictive information for patients with glioblastoma. The most important finding of our analysis is that in the absence of MGMT promoter methylation, longterm survival is very rare. For patients without this mutation, alternative treatments should be explored.
Keywords: glioblastoma, long-term survival, methyl guanine methyl transferase, prognostic factor
Published: 05.04.2017; Views: 151; Downloads: 16
Full text (556,97 KB)
An EMI filter selection method based on spectrum of digital periodic signalMarko Podberšič
, Vojko Matko
, Matjaž Šegula
, 2006, original scientific article
Abstract: This paper describes a new method for the selection of an appropriate signal lineElectromagnetic Interference (EMI) filter. To date, EMI filter selection has been based on the measurement of the radiation of the entire device. The new selection method based on the signal’s Fast Fourier Transform (FFT) measurement has proved to be efficient. The EMIfilter is optimized separately for each line. The method described in this paper involving aCentral Processor Unit (CPU) module demonstrates that the proposed FFT-based selection method is better than the radiation-based one. The radiation level in the frequency range 30MHz to 1 GHz is lower for approximate 2 – 6 dBμV/m.
Keywords: EMC, EMI filters, electrically long trace, typical frequency, sensor
Published: 22.06.2017; Views: 103; Downloads: 17
Full text (189,00 KB)
Long memory in the Croatian and Hungarian stock market returnsMejra Festić
, Alenka Kavkler
, Silvo Dajčman
, 2012, original scientific article
Abstract: The objective of this paper is to analyze and compare the fractal structure of the Croatian and Hungarian stock market returns. The presence of long memory components in asset returns provides evidence against the weak-form of stock market effi ciency. The starting working hypothesis that there is no long memory in the Croatian and Hungarian stock market returns is tested by applying the Kwiatkowski-Phillips-Schmidt-Shin (KPSS) (1992) test, Loʼs (1991) modified rescaled range (R/S) test, and the wavelet ordinary least squares (WOLS) estimator of Jensen (1999). The research showed that the WOLS estimator may lead to different conclusions regarding long memory presence in the stock returns from the KPSS and unit root tests or Loʼs R/S test. Furthermore, it proved that the fractal structure of individual stock returns may be masked in aggregated stock market returns (i.e. in returns of stock index). The main finding of the paper is that both the Croatian stock index Crobex and individual stocks in this index exhibit long memory. Long memory is identified for some stocks in the Hungarian stock market as well, but not for the stock market index BUX. Based on the results of the long memory tests, it can be concluded that while the Hungarian stock market is weak form efficient, the Croatian stock market is not.
Keywords: stock market, long memory, efficient-market hypothesis, Croatia, Hungary
Published: 18.07.2017; Views: 138; Downloads: 22
Full text (301,71 KB)
Effect of depreciation of the exchange rate on the trade balance of AlbaniaSafet Kurtović
, Blerim Halili
, Nehat Maxhuni
, 2017, original scientific article
Abstract: The paper investigates the effect of the real effective exchange rate depreciation of the lek on the trade balance of Albania using quarterly data from 1994 to 2015. Bounds testing cointegration approach, vector error correction model (VECM), and impulse response were used for the empirical analysis. The results of the study show a long-term cointegration between the real effective exchange rate (REER) and the trade balance (TB). Specifically, the REER depreciation positively affects the trade balance of Albania in both the long and short run, indicating the weak presence of the J-curve effect. Important recommendations were derived from the results.
Keywords: J-curve, cointegration, elasticity, short-term effect, long-term effect
Published: 03.05.2018; Views: 74; Downloads: 5
Full text (626,39 KB)