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181.
182.
We consider a multi-server non-preemptive queue with high and low priority customers, and a decision maker who decides when waiting customers may enter service. The goal is to minimize the mean waiting time for high-priority customers while keeping the queue stable. We use a linear programming approach to find and evaluate the performance of an asymptotically optimal policy in the setting of exponential service and inter-arrival times. 相似文献
183.
Excimer laser ablation of a thin Cr film on a glass substrate was evaluated through detecting acoustic emission arising from the ablation process and observing surface morphology. In the experiment, an acoustic emission transducer was coupled to the sample to acquire acoustic emissions of laser–material interaction and an oscilloscope was used to record the signals. The patterned areas were examined by using an optical microscope. Characteristics of the acoustic emissions were studied through applying a range of signal analysis tools. Several features (e.g., average power, RMS) showed a clear linkage with the ablation mechanism of thin Cr film when varying the fluence of the laser source. Moreover, the damage to the glass substrate was well discriminated by the extracted features. In sum, evaluation of acoustic emissions not only provided a tool to study the ablation mechanisms of the thin metal film but also addressed a monitoring strategy for excimer laser micromachining. 相似文献
184.
1-Aryl-3-phenethylamino-1-propanone hydrochlorides 1-10, which are potentialpotent cytotoxic agents, were synthesized via Mannich reactions using paraformaldehyde,phenethylamine hydrochloride as the amine component and acetophenone, 4'-methyl-, 4'-methoxy-, 4'-chloro-, 4'-fluoro-, 4'-bromo-, 2',4'-dichloro-, 4'-nitro-, 4'-hydroxyacetophenone or 2-acetylthiophene as the ketone component. Yields were in the87-98 % range. Of the compounds synthesized, compounds 2, 6-8 and 10 were new. Theoptimum reaction conditions were investigated by changing the mol ratios of the reactants,the solvents and the acidity levels using 1 and 10 as representative targets. It was observedthat the best mol ratio of the ketone, paraformaldehyde and phenethylamine hydrochloridewas 1:1.2:1 (compared with a 2:2.1 ratio), and the most suitable reaction medium wasethanol containing concentrated hydrochloric acid (compared with only ethanol or nosolvent). This study may serve as a guide for the conditions of the reactions to synthesizecompounds having similar chemical structures. 相似文献
185.
Ebru Ucakturk Chao Cai Lingyun Li Guoyun Li Fuming Zhang Robert J. Linhardt 《Analytical and bioanalytical chemistry》2014,406(19):4617-4626
A capillary zone electrophoresis–laser-induced fluorescence detection (CZE-LIF) method was developed for the simultaneous analysis of disaccharides derived from heparan sulfate, chondroitin sulfate/dermatan sulfate, hyaluronan, and keratan sulfate. Glycosaminoglycans (GAGs) were first depolymerized with the mixture of GAG lyases (heparinase I, II, III and chondroitinase ABC and chondroitinase AC II) and GAG endohydrolase (keratinase II) and the resulting disaccharides were derivatized by reductive amination with 2-aminoacridone. Nineteen fluorescently labeled disaccharides were separated using 50 mM phosphate buffer (pH 3.3) under reversed polarity at 25 kV. Using these conditions, all the disaccharides examined were baseline separated in less then 25 min. This CZE-LIF method gave good reproducibility for both migration time (≤1.03 % for intraday and ≤4.4 % for interday) and the peak area values (≤5.6 % for intra- and ≤8.69 % for interday). This CZE-LIF method was used for profiling and quantification of GAG derivative disaccharides in bovine cornea. The results show that the current CZE-LIF method offers fast, simple, sensitive, reproducible determination of disaccharides derived from total GAGs in a single run. Figure
Separation of 19 glycosaminoglycan-derived disaccharides using CZE. These disaccharides are HA (pink), HS (blue), CS (green) and KS (red). Residual AMAC tag is shown in orange. 相似文献
186.
An experimental study exploring colour ranges corresponding to different colour names has been conducted. Available colour terms in Turkish language have been identified and the most frequently known or used colour terms have been attained. Using the Munsell Color System, colour ranges reflecting the colour naming and colour perception of Turkish people, have been constructed for each colour term. The discussion of the findings and observations during the research are also included. 相似文献
187.
This article presents a semigroup approach for the mathematical analysis of the inverse coefficient problems of identifying the unknown coefficient k(u(x,t)) in the quasi‐linear parabolic equation ut(x,t)=(k(u(x,t))ux(x,t))x, with Dirichlet boundary conditions u(0,t)=ψ0, u(1,t)=ψ1. The main purpose of this paper is to investigate the distinguishability of the input–output mappings Φ[?]:?? →C1[0,T], Ψ[?]:??→C1[0,T] via semigroup theory. In this paper, it is shown that if the null space of the semigroup T(t) consists of only zero function, then the input–output mappings Φ[?] and Ψ[?] have the distinguishability property. It is also shown that the types of the boundary conditions and the region on which the problem is defined play an important role in the distinguishability property of these mappings. Moreover, under the light of measured output data (boundary observations) f(t):=k(u(0,t))ux(0,t) or/and h(t):=k(u(1,t))ux(1,t), the values k(ψ0) and k(ψ1) of the unknown diffusion coefficient k(u(x,t)) at (x,t)=(0,0) and (x,t)=(1,0), respectively, can be determined explicitly. In addition to these, the values ku(ψ0) and ku(ψ1) of the unknown coefficient k(u(x,t)) at (x,t)=(0,0) and (x,t)=(1,0), respectively, are also determined via the input data. Furthermore, it is shown that measured output data f(t) and h(t) can be determined analytically by an integral representation. Hence the input–output mappings Φ[?]:??→ C1[0,T], Ψ[?]:??→C1[0,T] are given explicitly in terms of the semigroup. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
188.
Ebru Ozbilge 《Mathematical Methods in the Applied Sciences》2008,31(11):1333-1344
In this article, a semigroup approach is presented for the mathematical analysis of the inverse coefficient problems of identifying the unknown diffusion coefficient k(u(x, t)) in the quasi‐linear parabolic equation ut(x, t)=(k(u(x, t))ux(x, t))x, with Dirichlet boundary conditions ux(0, t)=ψ0, u(1, t)=ψ1. The main purpose of this work is to analyze the distinguishability of the input–output mappings Φ[·] : ??→C1[0, T], Ψ[·] : ??→C1[0, T] using semigroup theory. In this article, it is shown that if the null space of semigroups T(t) and S(t) consists of only a zero function, then the input–output mappings Φ[·] and Ψ[·] have the distinguishability property. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
189.
Melek Erol 《Chemical Papers》2010,64(4):482-490
In this study, bioactivity of glass in the system SiO2-CaO-Al2O3-P2O5-Na2O-MgO-CaF2 was investigated. For this purpose, a glass sample was prepared by the traditional melting method. Crystallization behavior
of bioactive glass was also investigated using differential thermal analyses. The Avrami constant of bioactive glass sample
calculated according to the Ozawa equation was 3.72 ± 0.4, which indicates bulk crystallization. Using the Matusita-Sakka
and the Kissinger equations, activation energy of crystal growth was determined as (394 ± 17) kJ mol−1 and (373 ± 12) kJ mol−1, respectively. These results indicate that the crystallization activation energy data of bioactive glass obtained in this
study are accurate and reliable. Bioactivity of the resultant glass sample was analyzed by immersion in simulated body fluid.
Scanning electron microscopy, thin film X-ray diffraction, ultraviolet spectroscopy and inductively coupled plasma techniques
were used to monitor changes in the glass surface and the simulated body fluid composition. The results revealed that a hydroxyapatite
layer was formed on the glass surface after 21 days of immersion in SBF. Formation of the hydroxyapatite layer confirmed the
bioactivity of the glass in the system SiO2-CaO-Al2O3-P2O5-Na2O-MgO-CaF2. In addition, physical and mechanical properties of the sample were measured to determine changes in the properties with
the immersion time. The results show that bioactive glass maintained its strength during the immersion in a simulated body
fluid solution. 相似文献
190.
This article presents a semigroup approach to the mathematical analysis of the inverse parameter problems of identifying the unknown parameters p(t) and q in the linear parabolic equation ut(x, t) = uxx + qux(x, t) + p(t)u(x, t), with Dirichlet boundary conditions u(0, t) = ψ0, u(1, t) = ψ1. The main purpose of this paper is to investigate the distinguishability of the input-output mapping Φ[·]:P→H1,2[0,T], via semigroup theory. In this paper, it is shown that if the nullspace of the semigroup T(t) consists of only zero function, then the input-output mapping Φ[·] has the distinguishability property. It is also shown that the types of the boundary conditions and the region on which the problem is defined play an important role in the distinguishability property of the mapping. Moreover, under the light of the measured output data ux(0, t) = f(t) the unknown parameter p(t) at (x, t) = (0, 0) and the unknown coefficient q are determined via the input data. Furthermore, it is shown that measured output data f(t) can be determined analytically by an integral representation. Hence the input-output mapping Φ[·]:P→H1,2[0,T] is given explicitly interms of the semigroup. 相似文献