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排序方式: 共有399条查询结果,搜索用时 46 毫秒
1.
Arnon Arazi Eshel Ben-Jacob Uri Yechiali 《Mathematical Methods of Operations Research》2005,62(3):453-466
We consider a Jackson-type network comprised of two queues having state-dependent service rates, in which the queue lengths
evolve periodically, exhibiting noisy cycles. To reduce this noise a certain heuristic, utilizing regions in the phase space
in which the system behaves almost deterministically, is applied. Using this heuristic, we show that in order to decrease
the probability of a customers overflow in one of the queues in the network, the server in that same queue – contrary to intuition
– should be shut down for a short period of time. Further noise reduction is obtained if the server in the second queue is
briefly shut down as well, when certain conditions hold. 相似文献
2.
The set D of distinct signed degrees of the vertices in a signed graph G is called its signed degree set. In this paper, we prove that every non-empty set of positive (negative) integers is the
signed degree set of some connected signed graph and determine the smallest possible order for such a signed graph. We also
prove that every non-empty set of integers is the signed degree set of some connected signed graph. 相似文献
3.
4.
1<q<2 L:=
n=1
1/q
n=1/q–1. [0,1]
n()=1, A
n:=
i=1
n–1
i(x)/qi+1/n
x
n(x)=0, n>. , =
n=1
n(x)/qn. F: [0,L]R , F(x)=
n=1
n(x)an,
n=1
¦a
n¦<. [0,L]. q(1,2), . , q(1, 2), . . 相似文献
5.
Пустьq∈(1, 2) иL=(q?1)?1. Дляz∈[0,L] обозначимδ(z) функцию, для которойδ(z)=1, еслиz≧1/q иδ(z)=0, еслиz<1/q. Пустьy(z) определяется из урав ненияz= =δ(z)q ?1+y(z)q ?1, и регулярное представление \(\mathop \Sigma \limits_{n = 1}^\infty \varepsilon _n \left( x \right)q^{ - n} \) аргументах определя ется из следующих соотношен ий: $$x = x_0 , \varepsilon _n \left( x \right) = \delta \left( {x_n } \right), x_{n + 1} = y\left( {x_n } \right).$$ ФункцияF: [0,L]→C называе тся аддитивной, если о на представляется в вид е $$F\left( x \right) = \mathop \Sigma \limits_{n = 1}^\infty \varepsilon _n \left( x \right)a_n ,$$ где ε ¦a n ¦<∞. «Бесконеч ное» представление 1=εl i q ?1 числа 1 определяется с ледующим образом: еслие n (1)=1 для б есконечно многихп, т оl n =ε n (1) (n=1, 2, ...); если ? максим альный индекс, для которогоε s (1)=1, то $$l_{ks + 1} = \left\{ \begin{gathered} \varepsilon _i \left( 1 \right) \left( {k = 0, 1, 2, ...; i = 1, ..., s - 1} \right) \hfill \\ 0 \left( {i = 0; k = 1, 2, ...} \right). \hfill \\ \end{gathered} \right.$$ В более ранней работе, опубликованной в это м журнале, авторы доказали, что а ддитивная функция является неп рерывной на отрезке [0,L] тогда и только тогда, когда ра венство $$a_n = \mathop \Sigma \limits_{i = 1}^\infty l_i a_{n + 1} $$ выполняется для всехn∈N. В настоящей работе ра ссматриваются непре рывные функции для которых в ыполняются дополнительные усло вия видаa n =O(q ??n ) (0≦1),a n ≧0. Анализируются их свя зи с корнями функцииG(z)=1 +ε l i z i . Доказы вается, что непрерывн ая аддитивная функция и ли вляется линейной, или нигде не дифференцир уема на отрезке [0,L]. 相似文献
6.
A low-background -counter and a simple direct method, based on total -counting, have been developed in order to estimate the concentration of uranium at the g/g level in ordinary rock samples. The method is a relative one; international standards have been used for calibration. Only 3 g of rock powder is needed. Combining this method with -spectrometry, direct determination of238U (independently of226Ra) becomes possible near the above concentration level. 相似文献
7.
Freedberg DI 《Journal of the American Chemical Society》2002,124(10):2358-2362
A simple solution NMR method is presented for pucker determination of five-membered rings using only residual dipolar couplings obtained in a single liquid crystalline medium, DMPC/DHPC bicelles (DMPC = dimyristoylphosphatidylcholine; DHPC = dihexanoylphosphatidylcholine). The method was applied to determine the pucker of the fructofuranosyl ring of sucrose. The results indicate a fructofuranosyl pucker phase in the 20 degrees - 70 degrees range. The pucker phases are in agreement with those from previous NMR and optical spectroscopic studies and, importantly, do not rely on empirically parametrized Karplus curves. Furthermore, the analysis implies more than one stable pucker phase and rapid ring interconversion in this range. The present results suggest that using residual dipolar couplings alone can reveal multiple conformations present in solution. Hence, when a sufficient number of residual dipolar coupling constants is measured, the outcome is a robust, reliable, and independent route for determining carbohydrate and nucleic acid structure by NMR spectroscopy. 相似文献
8.
Freedberg DI Venable RM Rossi A Bull TE Pastor RW 《Journal of the American Chemical Society》2004,126(33):10478-10484
The HNCO NMR pulse sequence was applied to three selectively labeled (15)N and (13)C isotopic homologues of the peptide Ac-WAAAH(AAARA)(3)A-NH(2) to probe directly for hydrogen bonds between residues 8 and 11 (characteristic of a 3(10)-helix), 8 and 12 (alpha-helix), and 8 and 13 (pi-helix). The experiments demonstrate conclusively, and in agreement with circular dichroism studies, that the center of the peptide is alpha-helical; there is no discernible 3(10)- or pi-helix at these specific positions. Molecular dynamics simulations of the preceding peptide and Ac-(AAAAK)(3)A-NH(2) in water using the potential energy parameter set CHARMM22/CMAP correctly yield an alpha-helix, in contrast to simulations with the set CHARMM22, which result in a pi-helix. 相似文献
9.
10.
Crespo A Martí MA Estrin DA Roitberg AE 《Journal of the American Chemical Society》2005,127(19):6940-6941
A novel technique for computing free energy profiles in enzymatic reactions using the multiple steering molecular dynamics approach in the context of an efficient QM-MM density functional scheme is presented. The conversion reaction of chorismate to prephenate catalyzed by the Bacillus subtilis enzyme chorismate mutase has been chosen as an illustrative example. 相似文献