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1.
2.
Pumping requirements of pulsed and continuous wave (CW) 2 m Tm : Ho lasers are investigated experimentally and theoretically for excitation at 800 nm. The influence of the pulse duration on threshold is measured using a chopped Ti : Al2O3 laser. Based on the experimental and simulated results the spatial and temporal pump requirements in future quasi-CW high-power diode-pumped 2 m Tm : Ho lasers are determined. The experiments and the model allow the evaluation of different loss mechanisms and indicate significant 540 nm emitting loss mechanisms. 相似文献
3.
Collocation Methods for Weakly Singular Second-kind Volterra Integral Equations with Non-smooth Solution 总被引:2,自引:0,他引:2
Collocation type methods are studied for the numerical solutionof the weakly singular Volterra integral equation of the secondkind:
where the solution (t) is assumedto have the form f(t) = x(t)+r?(t), x and being sufficientlysmooth. The solution is approximated near zero by a linear combinationof powers of t?, and away from zero by the usual polynomialrepresentation. Convergence is proved and many numerical experimentsare carried out with examples from the literature. A comparisonis made with a method of Brunner & Norsett (1981), originallydeveloped for (1) with a smooth solution. Special attentionis paid to the numerical approximation of the so-called momentintegrals which emerge in the collocation scheme. 相似文献
4.
Markus Balmer Dr. Florian Weigend Prof. Dr. Carsten von Hänisch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):4914-4919
The N-heterocyclic carbene (NHC)-stabilized phosphinidenide, SIMesPK [SIMes=1,3-bis(2,4,6-trimethylphenyl)imidazolidine-2-ylidene], was used as an (NHC)P-transfer reagent for the synthesis of the low-valent Group 14 ate complexes K[(SIMesP)3E] (E=Ge: 2 , Sn: 3 , Pb: 4 ), which were characterized by 1H NMR, 31P NMR, IR spectroscopy as well as elemental and X-ray analysis. Furthermore, SIMesPK was used in reactions with potassium amides and alkoxides to form the molecular phosphorus–potassium clusters [K4(SIMesP)2(hmds)2] [ 5 , hmds=N(SiMe3)2] and [K6(SIMesP)2(OtBu)4] ( 6 ). Finally, the reaction of SIMesPK with Li[Al(OC4F9)4] led to the potassium-rich ionic compound [(SIMesP)4K5][Al(OC4F9)4] ( 7 ). 相似文献
5.
P. Balmer 《Mathematische Annalen》2002,324(3):557-580
To any triangulated category with tensor product , we associate a topological space , by means of thick subcategories of K, à la Hopkins-Neeman-Thomason. Moreover, to each open subset U of this space , we associate a triangulated category , producing what could be thought of as a presheaf of triangulated categories. Applying this to the derived category of perfect complexes on a noetherian scheme X, the topological space turns out to be the underlying topological space of X; moreover, for each open , the category is naturally equivalent to . As an application, we give a method to reconstruct any reduced noetherian scheme X from its derived category of perfect complexes , considering the latter as a tensor triangulated category with .
Received: 28 January 2002 / Published online: 6 August 2002 相似文献
6.
B. Balmer P. Kaufmann W. Baumgartner 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1972,23(6):1014-1017
Ohne Zusammenfassung 相似文献
7.
8.
Summary A model R-18 Weissenberg Rheogoniometer operating in the continuous shear mode was used to generate shear viscosity vs. shear rate data on male and female human whole saliva. These data were found to accurately follow the Sisko model,
, whereµ is the shear viscosity at shear rate
is the asymptotic shear viscosity at infinite shear rate, andK andn are constants. Data were collected on the effects of food, coffee, caffeine, and aspirin as functions of time. Studies were also made on the effects of emotional stress, donor sex and age.The saliva viscosity increased with time and then decreased to the basal value for most ingested materials. Emotional stress was found to elevate the saliva viscosity. On the other hand, no significant difference was found between the average saliva viscosities of male and female groups. Also, no significant effect of donor age was detected.
With 4 figures and 6 tables 相似文献
Zusammenfassung Mit Hilfe eines Weissenberg-Rheogoniometers (Typ R-18) wurden bei stationärem Betrieb Scherviskositätskurven in Abhängigkeit von der Schergeschwindigkeit für den Speichel von Männern und Frauen gemessen. Man fand, daß sich die Meßwerte hinreichend genau durch ein Sisko-Modell, , beschreiben lassen, woµ die Scherviskosität bei der Schergeschwindigkeit die asymptotische Scherviskosität bei unendlich großer Schergeschwindigkeit sowieK undn weitere Konstanten bedeuten. Diese Messungen verfolgten die Wirkung von Nahrung, Kaffee, Coffein und Aspirin als Funktion der Zeit. Untersucht wurde weiterhin der Einfluß von emotionaler Spannung, sowie Geschlecht und Alter der Spender.Die Speichelviskosität stieg bei den meisten eingenommenen Stoffen mit der Zeit zuerst an, um danach wieder auf den Normalwert abzusinken. Ebenso fand man, daß emotionale Spannung eine Viskositätserhöhung hervorruft. Dagegen wurden bei Gruppen von Männern und Frauen keine signifikanten Unterschiede gefunden, und ebenso wurde kein gesicherter Einfluß des Alters festgestellt.
With 4 figures and 6 tables 相似文献
9.
Horseradish peroxidase (HRP) is immobilized in three easy steps on SiO(2) surfaces with the help of a polycationic second generation dendronized polymer (denpol) and the biotin-avidin system. This stepwise immobilization process is monitored and quantitatively analyzed with the transmission interferometric adsorption sensor. Partially biotinylated denpol is first adsorbed onto SiO(2) , followed by addition of avidin and then of biotinylated HRP. Denpols in their molecular structure combine properties of polymers as well as dendrimers which are found to be of clear advantage for this type of non-covalent enzyme immobilization. With respect to the reproducibility of the adsorption process and with respect to the stability of the adsorbed polymer layer, the denpol is superior to α-poly-D-lysine which is used as a reference polymer. Furthermore, HRP immobilized with the denpol on commercial glass slides remains considerably more active upon storage as compared to HRP immobilized with the help of α-poly-D-lysine with a similar number of repeating units. The ease of the denpol-mediated HRP immobilization and the high stability of the immobilized enzyme are promising for bioanalytical applications. 相似文献
10.
A.R. Präg F. Löwenthal R. Tommasini J.E. Balmer 《Applied physics. B, Lasers and optics》1998,66(5):561-566
2 . By using a 0.7% prepulse that precedes the main pulse by 5 ns and applying a total pump energy of 100 J or less, the J=0-1
lasing is at least one order of magnitude higher than the non-lasing background. For the 32.6-nm line of Ti, the 25.5-nm line
of Fe, and the 23.1-nm line of Ni, gain coefficients of (±) 4.20.4cm-1, (±) 3.90.3cm-1, and (±) 3.60.6cm-1, respectively, were measured for 2.4-cm-long curved targets, resulting in gain–length products of ∼10. Angle-resolved spectra
indicate a beam divergence of 3 mrad (FWHM), typically. The space-resolved spectra show that the J=0-1 lasing lines are emitted
from an approximately 60-μm-wide (FWHM) plasma region, whereas the nearby continuum emission is produced in a considerably
broader plasma region of ∼250 μm. Lasing at 25.5 nm in neon-like iron was observed at a pump power as low as 180 GW (∼9 TW/cm2), with, however, considerable shot-to-shot scatter in the absolute laser output.
Received: 5 September 1997/Revised version: 10 November 1997 相似文献