78,349 research outputs found
Practical application of on-line partial discharge monitoring technique on 500kV shunt reactor
No full textConsidering the damage mechanism of oil-impregnated paper insulation in power transformers, shunt reactors and other high voltage electrical apparatus caused by partial discharge, a concept of “destructive partial discharge” is introduced in this paper. The intensity of this discharge is regarded as several thousands pico-coulomb (pC) and may cause the insulation a fatal damage. An oil-paper insulation is usually able to withstand this type of partial discharge for a period of time prior to failure. This provides engineers a time window to detect it. This paper describes an on-line partial discharge monitoring system for 500kV shunt reactors. The commission results from 3 single-phase shunt reactors either connected or disconnected to the grid showed that the on-line partial discharge detecting system has a high noise immunising ability. Two years later after the installation, a pre-warning signal was received from one shunt reactor indicating the existence of an intermittent discharge. The acoustic emission system located its position at the low end of the high voltage bushing in the oil. Dissolved gasses analysis (DGA) in the oil suggested the presence of partial discharge, as acetylene (C2H2) was as high as 20ppm. PD activity was further confirmed by a physical examination on the reactor
Pharmacoeconomic analysis of adjuvant oral capecitabine vs intravenous 5-FU/LV in Dukes' C colon cancer: the X-ACT trial
No full textOral capecitabine (Xeloda<sup>®</sup>) is an effective drug with favourable safety in adjuvant and metastatic colorectal cancer. Oxaliplatin-based therapy is becoming standard for Dukes' C colon cancer in patients suitable for combination therapy, but is not yet approved by the UK National Institute for Health and Clinical Excellence (NICE) in the adjuvant setting. Adjuvant capecitabine is at least as effective as 5-fluorouracil/leucovorin (5-FU/LV), with significant superiority in relapse-free survival and a trend towards improved disease-free and overall survival. We assessed the cost-effectiveness of adjuvant capecitabine from payer (UK National Health Service (NHS)) and societal perspectives. We used clinical trial data and published sources to estimate incremental direct and societal costs and gains in quality-adjusted life months (QALMs). Acquisition costs were higher for capecitabine than 5-FU/LV, but higher 5-FU/LV administration costs resulted in 57% lower chemotherapy costs for capecitabine. Capecitabine vs 5-FU/LV-associated adverse events required fewer medications and hospitalisations (cost savings £3653). Societal costs, including patient travel/time costs, were reduced by >75% with capecitabine vs 5-FU/LV (cost savings £1318), with lifetime gain in QALMs of 9 months. Medical resource utilisation is significantly decreased with capecitabine vs 5-FU/LV, with cost savings to the NHS and society. Capecitabine is also projected to increase life expectancy vs 5-FU/LV. Cost savings and better outcomes make capecitabine a preferred adjuvant therapy for Dukes' C colon cancer. This pharmacoeconomic analysis strongly supports replacing 5-FU/LV with capecitabine in the adjuvant treatment of colon cancer in the UK
Mutation frequencies following the 5-FU-, 4NQO-, and CPT-treatment.
No full textA), C), and E) The frequencies of overall Lys+ mutations following treatments with 5-FU (10 μM), CPT (100 μM), or 4NQO (0.2 μg/mL), respectively, for 24 hrs. B), D), and F) The frequencies of the uracil-dependent A>C and T>G mutations following treatments with 5-FU, CPT and 4NQO, respectively. Error bars indicate 95% confidence intervals. The number of cultures used to determine the frequencies of mutations and the numerical values of the median mutation frequencies and the confidence intervals represented as graphs in this figure are listed in S4 Table.</p
Influence of ac ageing on space charge dynamics in LDPE
No full textPolymeric materials have been widely used as insulation in power industry due to their excellent electrical properties. However, these properties deteriorate in time irreversibly when the material is subjected to electric stress. Although space charge is believed to play an important role in ac ageing, exact mechanisms are poorly understood due to very limited experimental data. In the present work efforts have been made to investigate the influence of ac ageing on space charge dynamics in low-density polyethylene (LDPE). LDPE films with 200mm were aged at 50 kV/mm at 50 Hz for various times at ambient temperature. Space charge dynamics in the samples prior to and after ageing were monitored using the pulsed electroacoustic (PEA) technique under dc electric stress. The results indicate that there is a significant amount of homocharge accumulation in the unaged sample due to charge injection. These injected charges are the captured by the deep traps originated from the interface between crystalline and amorphous regions in LDPE. Ageing under ac condition does not necessarily lead to an increase in amount of charge in the bulk but leads to an increase in mobility of charge carriers. Chemical analysis by infrared spectroscope (FTIR) reveals there are chemical changes taken place in the bulk of the material after ac ageing. It is believed that the chemical changes introduce shallow traps which promote the movement of charge carriers in the bulk. Consequently, the injected charges spread across the sample
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
Space charge characteristics of multi-layer oil-paper insulation under different DC voltages
No full textIn this paper, space charge in oil-paper insulation system has been investigated using the pulsed electroacoustic (PEA) technique. A series of measurements were carried out when the insulation system was subjected to different applied voltages. Charge dynamics in the insulation system during the volts-on, volts-off and decay have been analyzed. It has been found that homocharge injection occurred both at the anode and the cathode. Positive charges are observed to accumulate in the layers, which indicate that the oil-paper layer interfaces act as a barrier for positive charges. The decay tests showed that after 30min, about a quarter of space charges remained in the sample, about 90% charges disappeared after 2 hours. Finally, total charge variation in these tests were analyzed
Gemcitabine: Progress in the treatment of pancreatic cancer
No full textUnresectable pancreatic cancer has a dismal prognosis with a median survival of 3-5 months in untreated disease. Since the introduction of gemcitabine, pancreatic cancer may no longer be regarded a chemotherapy-resistant tumor. Treatment with single-agent gemcitabine achieved clinical benefit and symptoms improvement in 20-30% of patients. While 1-year survival was observed in 2% of 5-fluorouracil (5-FU)-treated patients, it was raised to 18% by single-agent gemcitabine. Good treatment tolerability and low incidence of side effects are clear advantages of single-agent gemcitabine. Improvement of efficacy is, however, expected from combination treatment. Gemcitabine and cisplatin given as first-line treatment in three studies achieved a median survival of 7.4-8.3 months. One-year survival was raised to 28% as reported in one study. Comparable activity was obtained by a combination of gemcitabine with 5-FU. Nine studies using gemcitabine in combination with standard-dose or high-dose 5-FU reported a median survival ranging from 5.5 to 13 months. Notwithstanding these promising results, recommendations regarding palliative chemotherapy of pancreatic cancer remain tentative and still need confirmation by presently ongoing phase III trials. Inclusion of pancreatic cancer patients into clinical trials should be a major goal. Outside clinical trials, patients should present with an adequate PS (Karnofsky-performance index greater than or equal to 70) to qualify for chemotherapy. Copyright (C) 2001 S. Karger AG, Basel
Shaanxi province (China), terraced loess mountains between Fu Xian and Zhangcunyi
No full textPlateau surface betw. Fu-hsien [Fu Xian] & Chang-ts'an-I [Zhangcunyi], looking S. W. from nr. Tai-hui-ts'un, Y8 - Y10, Shensi [Shaanxi] F.G.C.GrayscaleClapp Nitrate Negatives, Box
Development of composite calibration standard for quantitative NDE by ultrasound and thermography
No full textInspection of aircraft components for damage utilizing ultrasonic Non-Destructive Evaluation (NDE) is a time intensive endeavor. Additional time spent during aircraft inspections translates to added cost to the company performing them, and as such, reducing this expenditure is of great importance. There is also great variance in the calibration samples from one entity to another due to a lack of a common calibration set. By characterizing damage types, we can condense the required calibration sets and reduce the time required to perform calibration while also providing procedures for the fabrication of these standard sets. We present here our effort to fabricate composite samples with known defects and quantify the size and location of defects, such as delaminations, and impact damage. Ultrasonic and Thermographic images are digitally enhanced to accurately measure the damage size. Ultrasonic NDE is compared with thermography.This proceeding may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.
This proceeding appeared in Dayal, Vinay, Zach G. Benedict, Nishtha Bhatnagar, and Adam G. Harper. "Development of composite calibration standard for quantitative NDE by ultrasound and thermography." In AIP Conference Proceedings, vol. 1949, no. 1, p. 060006. AIP Publishing LLC, 2018, and may be found at
DOI: 10.1063/1.5031552.
Copyright 2018 The Author(s).
Posted with permission
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