Pengaruh Medan Listrik Terhadap Komponen Elektronik

Sutong GIL utility tunnel project is a significant part of Huainan-Nanjing-Shanghai UHV AC transmission project. Sutong GIL connects 1000kV over-head transmission lines from Taizhou and Suzhou stations, and its length is about 5.5km. High voltage and large power flow of UHV AC transmission lines produce large induction current, which will cause difficult-extinguished secondary arc and reclosing failure.To solve the above problem, induction current rapid release devices are installed at both sides of Sutong GIL. Thus, there are four grounding devices for the same loop of Taizhou-Suzhou transmission lines, and the induction voltage and current are different under various grounding conditions, which should be concerned during system commissioning. Sutong GIL project divides Taizhou-Suzhou transmission lines into two parts, and the both open-looped over-head parts are earlier completed. This may cause voltage control and electromagnetic transient problems in system commissioning of the over-head parts of Huainan-Nanjing-Shanghai UHV AC transmission project. This paper focuses on key technical problems of system commissioning Sutong GIL utility tunnel project as well as Huainan-Nanjing-Shanghai UHV AC transmission project. Simulation studies have been carried out, and corresponding measures have been proposed, which have been applied in field commissioning.

According to the B–H curve and structural dimensions of the snubber by the Fink–Baker Method, the inductive voltage and the eddy current of any core tape with the thickness of the saturated regions are derived when the accelerator breakdown occurs. Using the Ampere's law, in each core tape, the eddy current of the core lamination is equal to the arc current, and the relation of the thickness of the saturated regions for different laminations can be deduced. The total equivalent resistance of the snubber can be obtained. The transient eddy current model based on the stray capacitance and the equivalent resistance is analyzed, and the solving process is given in detail. The exponential time constant and the arc current are obtained. Then, the maximum width of the lamination and the minimum thickness of the core tape are determined. The experimental time constant of the eddy current obtained, with or without the bias current, is approximately the same as that by the analytical method, which proves the accuracy of the adopted assumptions and the analysis method.

The response of transformer windings due to the impact of high voltage surges has evoked the attention of insulation engineers for almost a century. The reason is simple: These fast rising voltages give rise to non-uniform voltage stress distribution along the coil sections and can endanger the insulation of high voltage power transformer windings. Hence an in depth knowledge of this is necessary for insulation engineers to design the winding insulation and also protective devices to be used to ensure that insulation failure does not take place when such fast rising voltages appear at the terminals of high voltage power transformers. In this paper, time domain analysis on model winding of a high voltage power transformer with 12-coil sections and 18-coil sections is being carried out to investigate its dynamic behaviour under a variety of fast rising impulse voltages. Simulation results of both the 12-coil sections and 18-coil sections of model winding impressed with full impulse, time-step and chopped impulse surge voltages with α=10 and 20 have been presented.

In recent years, inverter drive machines such as a hybrid vehicle and an electric vehicle are operated under high voltage pulse with high repetition rate. In this case, inverter surge is generated and affected the machine operation. Especially, the enameled wire of a motor is deteriorated due to the partial discharge (PD) and finally breakdown of the wire will occur. In order to investigate a PD on a resistant enameled wire, characteristics of PD in the twisted pair sample under bipolar repetitive impulse voltages are investigated experimentally. The relationship between the applied voltage and discharge current was measured at PD inception and extinction, and we estimated the repetitive PD inception and extinction voltages experimentally. The corresponding optical emission of the discharge was also observed by using an ICCD camera. Furthermore, ozone concentration due to the discharge was measured during the life-time test of the resistant enameled wires from a working environmental point of view.

One of the oldest and best known developmental screening tests was recently restandardized and revised as the Denver-II. Because it was published without evidence of its accuracy, the present study was undertaken with 104 children between 3 and 72 months of age attending one of five day-care centers. To determine the presence of developmental problems, children were administered individual measures of intelligence, speech-language, achievement, and adaptive behavior. A second psychological examiner, blind to the outcome of the diagnostic battery, administered the Denver-II. Developmental problems including language impairments, learning disabilities, mild mental retardation, and/or functional developmental delay were found in 17% of the children. The Denver-II identified correctly 83% and thus had high rates of sensitivity. However, more than half the children with normal development also received abnormal, questionable, or untestable Denver-II scores. Thus the test had limited specificity (43%) and a high overreferral rate. The alternative scoring method, categorizing questionable/untestable scores as normal, caused sensitivity to drop to 56% although specificity rose to 80%. Since neither scoring method produced acceptable levels of accuracy, an effort was made to locate the sources of accuracy and inaccuracy within the test. Only items in the language domain were modestly helpful in discriminating children with and without difficulties. The findings suggest that the authors of the Denver-II need to engage in further development of the instrument including revising scoring criteria and item placement in relation to children's ages. In the interim, test users should employ screening tests which are more accurate such as the Minnesota Inventories or the Battelle Developmental Inventory Screening Test.

The paper presents Echo State Network (ESN) as classifier to diagnose the abnormalities in mammogram images. Abnormalities in mammograms can be of different types. An efficient system which can handle these abnormalities and draw correct diagnosis is vital. We experimented with wavelet and Local Energy based Shape Histogram (LESH) features combined with Echo State Network classifier. The suggested system produces high classification accuracy of 98% as well as high sensitivity and specificity rates. We compared the performance of ESN with Support Vector Machine (SVM) and other classifiers and results generated indicate that ESN can compete with benchmark classifier and in some cases beat them. The high rate of Sensitivity and Specificity also signifies the power of ESN classifier to detect positive and negative case correctly.

Experimental and Theoretical Investigation of Transient Voltage Distribution in an 11 kV Industrial Motor Winding

Impulse generators with RC circuits form the foundation for producing surge voltages used in high-voltage equipment testing. In high-voltage engineering literature, the expressions for impulse voltage waveforms include known parameters of lightning or switching overvoltages, which are used to determine the amplitudes and time constants of impulse overvoltages in RC discharge circuits. However, both standards and scholarly publications often lack clarification for various ambiguities-such as the commonly cited factor of 1.67 for rise time-without providing rigorous physical or mathematical justification. All overvoltage parameters are typically defined axiomatically, and the existing formulas for designing impulse voltage generators are often inadequate. This paper presents implemented formulas and derived solutions that enable accurate determination of all parameters and electrical quantities of an RC circuit generating a specified impulse voltage waveform. For method verification, an adapted module of the MATLAB simulation package, psbsurgeovervoltage.mdl, was employed.

Results are reported from experiments in which steep-front, short- duration (SFSD) voltage impulses were imposed on various electrical distribution components. These pulses were generated by switching a section of charged, high voltage coaxial cable across the component under study. Components included underground distribution cable, terminators, insulators and arresters. SFSD voltage needed to flashover 15 kV polyethylene cable with a single pulse is approximately 625 kV peak. Strength of polyethylene cable decreases with increasing number of SFSD pulses, indicating cumulative degradation of the polymer. For 15 kV and 25 kV cable terminators, the SFSD CFO was over twice the rated standard lightning BIL for the same units. Similarly, porcelain suspension insulators required more than a doubling of voltage to decrease time to flashover from 1 microsecond to .1 microsecond. Arresters were found to respond rapidly to steep-front current pulses, but the arrester material itself was found to result in a higher discharge voltage for SFSD pulses. Arresters also showed a delay in turn-on of current following the arrival of a steep-front voltage surge.

Induction motors are reported as the horse power in industries. Due to its importance, researchers studied how to predict its faults in order to improve reliability. Condition health monitoring plays an important role in this field, since it is possible to predict failures by analyzing its operational data. This paper proposes the usage of vibration signals, combined with Higher-Order Statistics (HOS) and machine learning methods to detect broken bars in a squirrel-cage three-phase induction motor. The Support Vector Machines (SVM), Multi-Layer Perceptron (MLP), Optimum-Path Forest and Naive-Bayes were used and have achieved promising results: high classification rate with SVM, high sensitivity rate with MLP and fast training convergence with OPF.

Fifty samples of Salted Hydrocynus Froskalli Fish (Molouha) were subjected for enumeration, isolation and identification of Staph.aureus.34 strains (68%) of Staph.aureus were isolated, 16 (32%) were coagulase positive and 18 (36%) were coagulase negative, the mean Staph.aureuscount was 35x10 3 cfu/g.It was found that 46% of examined samples were unaccepted based on the Egyptian Organization for standardization and quality control.The antimicrobial sensitivity revealed that isolated coagulase positive Staph.aureuswere resistance to Neomycin, Penicillin, Kanamycin, Ampicillin, Chloramphenicol, Erythromycin, Oxytetracycline, Cloxacillin, Sulphamethoxazol, Ciprofloxacin, Cephalothin, Gentamicin, Methicillin and Vancomycin with a percentage of 100, 100, 93.7, 81.3, 75.0, 62.5, 56.3, 56.3, 50.0, 43.7, 37.5, 25.0, 25.0 and 6.3% respectively, whereas the high resistance rate was observed against Neomycin and Penicillin (100%) and the isolates showed 11 different patterns of antimicrobial sensitivity, whereas the high sensitive rate was observed with vancomycin (87.5%).Detection of mecA gene was done for all coagulase positive Staph.aureusstrains ( 16) by PCR using specific primer with amplification length of 533 pb.The obtained results showed that all (MRSA) isolates were positive for presence of mecA gene and one of these isolets could not produce enterotoxin, whereas two could produce SEA and one could produce SEC.

Association between urban garbage exposure and allergic diseases among sanitation practitioners: A cross-sectional study

For the problem of leak inductance energy and voltage spike, given in the fly-back photovoltaic converter system (hereinafter abbreviated as PV), a new physical circuit of RCD (resistor-capacitor-diode) is proposed which based on the Boost circuit topology to recovering leak inductance energy and depressing main switch voltage spike during the commutation of power MOSFET. The circuit can recycle the leak inductance energy effectively [1−2], and suppress output capacitance (hereinafter abbreviated as Coss) electric discharge which caused the voltage spike during MOSFET switch-on. In addition, after detailed analysis, the new physical circuit can solve the problem of the energy loss generate from the Coss electric discharge which is not pay more attention by the other papers. The new design can clamp the drain-source voltage and implement the control policy of soft-switch. In this paper, we give the theoretical derivation of the circuit parameter and the implemented physically experimental curve of the physical circuit by analyzing the causes of voltage spike generated. Compared with the traditional method, improved the converter efficiency from 94.2 % to 96.2 %, and the MPPT efficiency to 99.4 %.

Assessment and Diagnosis of Knee Injuries: The value of an experienced physiotherapist

To relate maternal and infant characteristics to newborn shoulder width and to evaluate the predictive value of newborn shoulder width measurement in cases of shoulder dystocia. Newborn shoulder width was systematically measured at birth during a period of 18 months. Department of Obstetrics and Gynaecology of Saint-Antoine University Hospital, Paris, France. A total of 2222 newborn shoulder width measurements were performed and 22 cases of true shoulder dystocia occurred during the study period. Newborn shoulder width measurements were reviewed and correlated with maternal age, parity, nonpregnant weight, weight gain during pregnancy, height, race, fasting glucose and one hour glucose levels, gestational age, birthweight and sex of the neonate. A receiver-operating characteristics curve was constructed to evaluate newborn shoulder width as a test for predicting shoulder dystocia. The mean newborn shoulder width was 122.06 mm (10.50 SD). Stepwise multiple regression showed that newborn shoulder width was significantly associated with birthweight (P < 0.001), parity (P = 0.04), and nonpregnant weight (P = 0.04). We estimated that the best cut off for shoulder dystocia prediction was a newborn shoulder width measurement with a low false positive rate (< 10%) in association with a high sensitivity rate. Therefore, newborn shoulder width measurement > or = 140 mm was selected. This measurement should have a low sensitivity of 27.27%, a specificity of 91.82%, a positive predictive value of 4.02%, and a negative predictive value of 99.01% for shoulder dystocia prediction. Nevertheless, birthweight > or = 4000 g should have a better predictive value retrospectively for shoulder dystocia. Newborn shoulder width measurement, which is strongly correlated with birthweight, still remains a poor predictor for shoulder dystocia, even when this evaluation is correct antenatally.