Čedomir A. Maluckov

Statistical analysis of the dynamic voltage electrical breakdown in nitrogen

The statistical analysis of the electrical breakdown in nitrogen at p=20 mbar using dynamic method is presented in this paper. The analysis was performed for the working voltage increase rates 50, 150, and 300 Vs/sup -1/. For each working, voltage increase rate a 1000 measurements were done. It was shown that results are lined up accidentally without any systematic trend. New form of breakdown voltage density distribution is suggested and verified with histograms of the breakdown voltage.

Statistical analysis of electrical breakdown time delay distributions in neon tube at 13.3 mbar

Results of the statistical analysis of the electrical breakdown time delay for a neon-filled tube at 13.3 mbar are presented in this paper. Experimental distributions of the breakdown time delay were established on the basis of 1000 successive and independent measurements, deviating from usual exponential distribution. Breakdown time delay distributions are numerically generated from the composition of two parameters, which correspond to the random variables of an exponential distribution and of a Gaussian distribution. Theoretical breakdown time-delay distribution is obtained from the convolution of the exponential and Gaussian distributions. The numerically generated and theoretical breakdown time delay distributions show good correspondence with the distributions of experimental data.

The application of convolution-based statistical model on the electrical breakdown time delay distributions in neon

Results of the statistical analysis of the electrical breakdown time delay for neon-filled tube at 6.5 mbar with and without /spl gamma/ and ultraviolet (UV) irradiation are presented in this paper. Experimental distributions of the breakdown time delay are established on the basis of 1000 successive and independent measurements for different exposition dose rates of /spl gamma/-irradiation, and UV illumination with known spectrum. Obtained experimental density distributions are modeled with convolution-based model, proposing two independent random variables with exponential and Gaussian distribution, respectively. The tendency of the breakdown time delay distribution to change shape from the exponential-like to the Gaussian-like is found by increasing the exposition rate of the /spl gamma/ irradiation. In addition, the characteristic strong reduction of the time delay is identified in the tube under the UV illumination.

On the complex structure of the breakdown time-delay distribution in a neon-filled diode at 4 mbar pressure

The unusual and complex structures of the breakdown time-delay distributions in a neon-filled diode at 4 mbar pressure for lower overvoltages are reported in this paper. Each distribution was established on the basis of the 1000 successive and independent measurements of the electrical breakdown time delay. It is concluded that the expected one-stage Laue distribution cannot be applied successfully because of the complex structures of the measured distributions. For very low overvoltages, multiple breakdown mechanisms seem to appear with different (by two orders of magnitude) mean values of the statistical time delay and formative time. A multi-stage model for the Lauegrams is used in order to fit our data.

Recognition of the Script in Serbian Documents Using Frequency Occurrence and Co-Occurrence Analysis

Any document in Serbian language can be written in two different scripts: Latin or Cyrillic. Although characteristics of these scripts are similar, some of their statistical measures are quite different. The paper proposed a method for the extraction of certain script from document according to the occurrence and co-occurrence of the script types. First, each letter is modeled with the certain script type according to characteristics concerning its position in baseline area. Then, the frequency analysis of the script types occurrence is performed. Due to diversity of Latin and Cyrillic script, the occurrence of modeled letters shows substantial statistics dissimilarity. Furthermore, the co-occurrence matrix is computed. The analysis of the co-occurrence matrix draws a strong margin as a criteria to distinguish and recognize the certain script. The proposed method is analyzed on the case of a database which includes different types of printed and web documents. The experiments gave encouraging results.

Breakdown-voltage memory effect in a neon-filled diode at 1 mbar

Results of the investigation of the breakdown-voltage distribution dependence on the relaxation time of the diode [the curve U~/sub b~/=f(/spl tau/)], i.e., memory effect, in neon at p=1 mbar are presented in this paper. The memory effect is determined for the diode-relaxation times 0.1-100 s. The applied voltage was linearly increased with the increasing rate 10 V/s. For each value of the relaxation time, the series of 200 successive and independent measurements were done. The numerical fitting of the theoretical expression of the breakdown-voltage distribution on the histograms of the experimentally established data was used to determined relative yield in the diode for the different relaxation times Y/Y/sub 0/=f(/spl tau/). Results show that the yield in the diode decreased in that time interval in one order of magnitude. Quantitative parameters for two-step decreasing and qualitative explanation of these dependencies are given.

An approach to the script discrimination in the Slavic documents

The paper deals with the problem of the script discrimination in old Slavic printed documents. Therefore, an algorithm for script classification and identification is proposed. It creates coded text from initial document. Then, the coded text is subjected to statistical analysis. As a result, the texture feature extraction is carried out. Obtained texture features are used as criteria for script classification and identification. The proposed method is tested on the samples of old Slavic printed documents written in Glagolitic, Cyrillic and Latin script.

Statistical analysis of the electrical breakdown time delay distributions in krypton

The statistical analysis of the experimentally observed electrical breakdown time delay distributions in the krypton-filled diode tube at 2.6mbar is presented. The experimental distributions are obtained on the basis of 1000 successive and independent measurements. The theoretical electrical breakdown time delay distribution is evaluated as the convolution of the statistical time delay with exponential, and discharge formative time with Gaussian distribution. The distribution parameters are estimated by the stochastic modelling of the time delay distributions, and by comparing them with the experimental distributions for different relaxation times, voltages, and intensities of UV radiation. The transition of distribution shapes, from Gaussian-type to the exponential-like, is investigated by calculating the corresponding skewness and excess kurtosis parameters. It is shown that the mathematical model based on the convolution of two random variable distributions describes experimentally obtained time delay ...

The application of convolution-based statistical model on the electrical breakdown time delay distributions in neon under /spl gamma/ and UV radiation

Results of the statistical analysis of the electrical breakdown time delay for neon-filled tube at 6.5 mbar with and without /spl gamma/ and ultraviolet (UV) irradiation are presented in this paper. Experimental distributions of the breakdown time delay are established on the basis of 1000 successive and independent measurements for different exposition dose rates of /spl gamma/-irradiation, and UV illumination with known spectrum. Obtained experimental density distributions are modeled with convolution-based model, proposing two independent random variables with exponential and Gaussian distribution, respectively. The tendency of the breakdown time delay distribution to change shape from the exponential-like to the Gaussian-like is found by increasing the exposition rate of the /spl gamma/ irradiation. In addition, the characteristic strong reduction of the time delay is identified in the tube under the UV illumination.

Experimental investigations of time delay distributions inside a commercial gas tube

The results of the commercial indicator gas tube investigation, using the time delay measuring method are presented in this paper. This tube is usually used as an indicator of many electrical appliances. Time delay distributions for voltages from 75 V up to 100 V and relaxation times from 1 ms to 20 ms are presented. The time delay distributions for voltages UW > 75 V have Gaussian shape, and for UW = 75 V are multimodal. The multimodal time delay distributions indicate several different mechanisms which lead to breakdown. It is also shown that gas discharge tube has very small memory effect, which indicates fast response after the long (out of use) time, and consequently good characteristic for indicator tube. This characteristic of the used commercial indicators gas discharge tubes is consequence of gas tube geometry causing several processes which lead to breakdown under the same experimental conditions.