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1.
Korner F. Lindmayer M. Kurrat M. Gentsch D. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(3):643-648
According to the relevant IEC standards vacuum circuit-breakers have to meet various needs, e.g. the interruption capability, making operations, and dielectric strength. Besides the interruption of short-circuit currents, switching of capacitive currents causes high stress of the circuit-breaker. Switching of capacitor banks, overhead lines, or cables leads to very small currents in comparison with short circuit currents. After current interruption the circuit-breaker must withstand twice the peak value of the system voltage. Furthermore, restrikes can lead to voltage multiplication. This conjunction of relatively small breaking currents with high voltage stress must be considered in detail. This work introduces a test arrangement for combined tests of making operation, current interruption, and dielectric stress of a vacuum gap under capacitive switching condition. A test vessel permits investigations of various contact materials and designs. It is connected to a synthetic test circuit which provides the appropriate test currents and capacitive voltage. During the test sequence the contacts are stressed by inrush-currents up to 4.5 kA peak, followed by a breaking operation at 500 A peak and a subsequent capacitive voltage up to 50 kV peak. Both the appearance of pre-ignitions at contact closing and the behavior under capacitive voltage stress after breaking are indications of the contact surface conditions. 相似文献
2.
VN Ngo H Korner MD Gunn KN Schmidt DS Riminton MD Cooper JL Browning JD Sedgwick JG Cyster 《Canadian Metallurgical Quarterly》1999,189(2):403-412
Mice deficient in the cytokines tumor necrosis factor (TNF) or lymphotoxin (LT) alpha/beta lack polarized B cell follicles in the spleen. Deficiency in CXC chemokine receptor 5 (CXCR5), a receptor for B lymphocyte chemoattractant (BLC), also causes loss of splenic follicles. Here we report that BLC expression by follicular stromal cells is defective in TNF-, TNF receptor 1 (TNFR1)-, LTalpha- and LTbeta-deficient mice. Treatment of adult mice with antagonists of LTalpha1beta2 also leads to decreased BLC expression. These findings indicate that LTalpha1beta2 and TNF have a role upstream of BLC/CXCR5 in the process of follicle formation. In addition to disrupted follicles, LT-deficient animals have disorganized T zones. Expression of the T cell attractant, secondary lymphoid tissue chemokine (SLC), by T zone stromal cells is found to be markedly depressed in LTalpha-, and LTbeta-deficient mice. Expression of the SLC-related chemokine, Epstein Barr virus-induced molecule 1 ligand chemokine (ELC), is also reduced. Exploring the basis for the reduced SLC expression led to identification of further disruptions in T zone stromal cells. Together these findings indicate that LTalpha1beta2 and TNF are required for the development and function of B and T zone stromal cells that make chemokines necessary for lymphocyte compartmentalization in the spleen. 相似文献
3.
T Korner 《Canadian Metallurgical Quarterly》1993,27(1):115-126
The mutant frequency of 6-thioguanine resistance (HPRT locus) in circulating T lymphocytes from 23 Fanconi anemia (FA) patients has been determined. The glycophorin A (GPA) in vivo cell mutants assay, which detects allele loss variant phenotypes arising from mutations in erythroid progenitor cells of GPA heterozygous MN individuals, has been applied in parallel to FA patients. No significant difference in frequency of HPRT- mutants was observed in FA compared to age matched healthy donors. In contrast, the mean frequency of GPA variant cells was elevated 31-fold for hemizygous NO variants and 8-fold for homozygous NN variants in FA patients over normal controls. In heterozygous FA parents, HPRT- mutant frequencies and GPA variant frequencies were within the normal range. Molecular analysis of HPRT- mutants has previously shown that FA cells have a high tendency to form deletions. Knowing that the cellular events allowing the detection of mutations at the HPRT and the GPA locus differ, our results emphasize the possible correlation between events of spontaneous loss of heterozygosity and genetic predisposition to cancer as observed in FA. 相似文献
4.
Korner J. Marton K. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1988,34(2):312-314
A probabilistic problem that arises for conflict resolution in random-access communication is treated. An earlier conjecture is disproved and a technique for finding lower bounds on the number of graphs of given structure needed to cover all edges of a given graph is developed 相似文献
5.
Efficacy of an advanced sewage treatment plant in southeast Queensland, Australia, to remove estrogenic chemicals 总被引:1,自引:0,他引:1
Leusch FD Chapman HF Korner W Gooneratne SR Tremblay LA 《Environmental science & technology》2005,39(15):5781-5786
The estrogenicity profile of domestic sewage during treatment at a medium-sized (3800 EP) advanced biological nutrient removal plant in Queensland, Australia, was characterized using a sheep estrogen receptor binding assay (ERBA) and the MCF-7 breast cancer cell proliferation assay (E-Screen). The raw influent was highly estrogenic (20-54 ng/L EEq), and primary treatment resulted in a slight increase in estrogenicity that was detected in one of the assays (6-80 ng/L). Concurrent chemical analysis suggested that most of the estrogenicity in the influent was due to natural hormones (>48%). Secondary activated sludge treatment followed by nitrification/denitrification effectively removed > 95% of the estrogenic activity (to <0.75-2.6 ng/L), and estrogenicity of the final tertiary-treated effluent was below the detection limit of both assays (<0.75 ng/L). 相似文献
6.
本文介绍了起绒、剪绒和磨绒三个加工工艺的目的和原理,也讨论了影响这些民因素。同时借助于产品实例进行了起绒织物的推荐介绍并对起绒、剪绒和磨绒织物的要求加以叙述。. 相似文献
7.
"When the anthropologist studies the value structure of a culture, he declares himself most competent to do so where the society under study is small and its institutions stable." The transforming and changing of values requires a great deal of time. "Can we scientists invade critically the area of values with no convictions, no moral banners, no preaching of gloom, no concept of right and wrong, invoking only the operational concept of 'adjustment'?" (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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9.
IK Bailey SD Anderson PJ Rozea L Bernstein G Nyberg PI Korner 《Canadian Metallurgical Quarterly》1976,92(4):416-426
1. Nine subjects with severe coronary artery disease were studied during graded "sprint" and "steady-state" exercise before and after intravenous administration of the beta-receptor antagonist alprenolol. During "sprint" workload was increased every minute until maximum work capacity (Wmax) was reached. "Steady-state" exercise was performed at work rates of 0.250, 0.50, and 0.75 of each subject's sprint Wmax. Variables measured included ST-segment depression, changes in heart rate, blood pressure, respiratory gas exchange, and arterial blood composition. Cardiac output (indirect Fick) was measured during "steady-state" exercise. 2. Alprenolol did not alter Wmax during "sprint" but reduced the incidence of angina in both types of exercise. After the drug work capacity was limited by symptoms and signs suggestive of mild left ventricular failure. 3. The relationship between workload (normalized in terms of Wmax) and ST-segment depression was curvilinear. Under control conditions a given rate of work during "steady-state" exercise was assocaited with more marked ST-segment depression than during "sprint". Alprenolol displaced the work-ST-depression curve to the right in each type of exercise; now a given rate of work produced similar ST-depressing during "steady-state" and "sprint" exercise. 4. Alprenolol attentuated the exercise tachycardia during both types of exercise. Cardiac output was lower in "steady-state" exercise after the drug than under control conditions. Metabolic effects included significant reduction in body oxygen consumption after alpreprenolol at 0.25 Wmax and diminished arterial lactate at 0.75 Wmax. The beneficial effects of the drug thus appeared to involve not only cardiac but peripheral effects on beta receptors. 5. Before alprenolol cardiac output was relatively fixed at all workloads, but after the drug there was a work-related rise in output in five out of nine subjects. Comparison with data in normal subjects suggested that in anginal subjects cardiac output at low "steady-state" workloads was inappropriately high. 相似文献
10.
Zero-error information theory 总被引:2,自引:0,他引:2
Korner J. Orlitsky A. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1998,44(6):2207-2229
The problem of error-free transmission capacity of a noisy channel was posed by Shannon in 1956 and remains unsolved, Nevertheless, partial results for this and similar channel and source coding problems have had a considerable impact on information theory, computer science, and mathematics. We review the techniques, results, information measures, and challenges encountered in this ongoing quest 相似文献