In this paper an algorithm is presented to determine the number of semisimple conjugacy classes for a given centralizertype for the Chevalley groupsSLn(q) andSUn(q). Moreover we give the exact number of regular semisimple classes of this groups and a summary of results on the generic classnumber of exceptional Chevalley groups of adjoint type.The first author acknowledges financial support by a grant of the Deutsche Forschungsgemeinschaft 相似文献
Zusammenfassung Ziel des Teilvorhabens, über das hier berichtet wird, was es, für eine Auswahl von physikalischen Effekten eine Zuordnung
von gestaltbeeinflussenden Merkmalen auf sehr abstrakter Ebene zu erreichen und damit eine n?here Charakterisierung der Wirkfl?chen
und Wirkr?ume zu erreichen die zur Umsetzung eines physikalischen Effektes notwendig sind. Die hieraus resultierenden Ergebnisse
sind dem Abschlu?bericht zu entnehmen [1]. Weiterführende Themen, die basierend auf den vorliegenden Erkenntnissen bearbeitet
werden, haben zum Ziel, die wesentlichen und entscheidenden Parameter einer Konstruktionsaufgabe zu erkennen und zukünftig
zielgerichtet L?sungsvarianten zu erstellen, um somit für eine Neukonstruktion sinnvolle L?sungsfelder sehr frühzeitig abzugrenzen. 相似文献
Histamine release and the subsequent activation of H2 receptors in the periaqueductal gray (PAG) are thought to be important components of morphine antinociception. In vivo microdialysis and antinociceptive testing were simultaneously applied in rats to characterize the effects of morphine on PAG histamine release and determine the relationship between histamine release and antinociception. In the absence of nociceptive (tail pinch) testing, morphine (12.8 mg/kg) induced a delayed, long-lasting release of histamine in the PAG. This effect of morphine was abolished by the opiate antagonist naltrexone (1 mg/kg) but was not mimicked by the mu-preferring agonist fentanyl (0.3 mg/kg), suggesting that activation of an opiate receptor other than, or in addition to, the mu receptor is necessary. In contrast to the findings with fentanyl in untested animals, fentanyl combined with nociceptive testing increased histamine release, even though testing alone had no such effect. Unexpectedly, tail pinch testing inhibited morphine-induced histamine release. These results show that the test procedure alters the action of opiates on histamine release, an effect likely to be the result of the stress of repeated tail pinch testing. Therefore, although histamine release may not be obligatory for all types of opiate antinociception, histamine in the PAG may function as a mediator of stress-induced potentiation of opiate antinociception. Even though the microdialysis technique has been acclaimed for its ability to assess neurochemical and behavioral characteristics simultaneously, the introduction of nociceptive testing clearly can alter the neurochemical systems under study. 相似文献
Many real-world problems are multi-objective optimization problems and evolutionary algorithms are quite successful on such problems. Since the task is to compute or approximate the Pareto front, multi-objective optimization problems are considered as more difficult than single-objective problems. One should not forget that the fitness vector with respect to more than one objective contains more information that in principle can direct the search of evolutionary algorithms. Therefore, it is possible that a single-objective problem can be solved more efficiently via a generalized multi-objective model of the problem. That this is indeed the case is proved by investigating the computation of minimum spanning trees.This work was supported by the Deutsche Forschungsgemeinschaft (DFG) as part of the Collaborative Research Center Computational Intelligence (SFB 531) and by the German-Israeli Foundation (GIF) in the project Robustness Aspects of Algorithms. 相似文献
A new microcalorimeter with eight parallel channels using robust, low cost sensors for characterization of coatings and adhesives is described and first experiments on coatings and adhesives are presented. The calorimetric sensors are based on thin glass plates (20 mm × 20 mm, thickness 150 μm) with heater and thermocouple sputtered on the surfaces (calorimetric active area of about 9 mm2). The setup allows heating and cooling experiments as well as isothermal measurements in the temperature-modulated mode with up to eight sensors in parallel. The measured quantities are the real (C′p) and imaginary part (C″p) of the complex heat capacity (), the related absolute value of the heat capacity () and the heat flow . An industrial computer (NI PXI system) with specific software for calibration and data recording controls the electronic components. Sensors can be embedded in a temperature controlled oven (heating and cooling by Peltier elements) or alternatively in a climatic cabinet with controlled temperature and humidity.
The method has been applied successfully to monitoring of film formation of aqueous polymer dispersions (styrene-acrylate copolymer) and curing of coatings. 相似文献
The corrosion behaviour of 13Cr-martensitic stainless steel (AISI 420) was investigated in CO2-H2S-Cl– environments typical of oil and gas wells under different CO2 and H2S partial pressures. The corrosion tests indicated that the AISI 420 steel was highly corrosion resistant to CO2-induced phenomena (general corrosion and carbonate S.C.C.), while in the H2S environment a high S.S.C.C. (Sulphide Stress Corrosion Cracking) susceptibility and high corrosion rates were found. Moreover, CO2 in CO2-H2S-Cl– systems inhibited general corrosion and S.S.C.C. phenomena by favouring the formation of a protective film. By means of X-ray photoelectron spectroscopy (XPS) the chemical nature of the films grown on AISI 420 in different environmental conditions was investigated and the following statements were drawn out:
CO2 favours the growth of a hydrated Cr-oxide rich protective film with a low Fe-oxide and sulphide content;
the presence of H2S favours the formation of less protective Fe-sulphide and Fe-oxide rich layers.
Furthermore from XPS results an index of protectivenessIp = Cr+3/ (Cr+3 + FeOX was defined and related to the environmental parameter
and to the corrosion rates. 相似文献
Brillouin scattering (BS), photon correlation spectroscopy (PCS), and ultrasonic (US) measurements were conducted to study the curing process of diglycidyl ether of bisphenol A with butane-1,4-diol at a curing temperature of 100°C. The experimental techniques probe the primary glass-rubber transition during the curing reaction. The primary relaxation time τ obtained from the BS and US velocity and absorption increases with curing time and hence the BS experiment measures τ at earlier stages of cure than the US experiment. The relaxation times at a different extent of reaction and for different measuring temperatures are consistent with BS, US, PCS, and DSC measurements and conform to a single reduced Vogel–Fulcher–Hesse–Tamann equation. Furthermore, the US experiments show evidence of secondary relaxations in the epoxy system. 相似文献
A series of composites of polycarbonate (PC) with 23 different contents of multiwalled carbon nanotubes (MWNT) was produced by melt mixing using the masterbatch dilution method. In dielectric measurements, AC conductivity and complex permittivity data obtained in the frequency range between 10−3 and 107 Hz at room temperature indicated the electrical percolation threshold at about 1.0 wt%.
The dynamic mode melt rheological measurements for the same samples at eight temperatures between 170 and 280 °C showed a visible change in the frequency dependence of dynamic moduli and the absolute value of the complex viscosity |η*| particularly at low frequencies. In literature these changes are sometimes related to so called ‘percolation threshold concentration’. Applying this picture to our experimental data we have to assume that the percolation threshold is strongly dependent on the measurement temperature. It changes from about 5 to 0.5 wt% MWNT by increasing the measurement temperature from 170 to 280 °C, respectively. This temperature dependence cannot be explained by a classical liquid-solid transition but may be related to the existence of a combined nanotube-polymer network. 相似文献