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排序方式: 共有69条查询结果,搜索用时 640 毫秒
51.
V. Evrard R. De Giacomi G. A. Korshenowski J. N. Rekeda B. O. Ljubin N. D. Buchmann W. D. Ugrjumov I. M. Korenman N. I. Tarassewitsch Je. S. Prshewalski Rufina W. Teiss J. M. Josefinowa-Goldfein L. Klinc E. Stotz S. C. Ganguly G. Semerano I. S. Rao A. P. Terentjew E. M. Terentjewa K. K. Magaram A. I. Neljubina Gertrud Woker Ilse Antener W. Traube Emil Fischer H. Schrades Ch. Valencien J. Deshusses E. T. Illing G. Illari A. Banchetti E. Storfer A. Lespagnol J. Bruneel A. G. Kuhlmann 《Analytical and bioanalytical chemistry》1942,124(9-10):351-361
52.
Klaartje De Buysser Philippe F. Smet Bart Schoofs Els Bruneel Dirk Poelman Serge Hoste Isabel Van Driessche 《Journal of Sol-Gel Science and Technology》2007,43(3):347-353
This paper describes the synthesis of ZrW2O8 by the use of an aqueous citrate-gel method in order to prepare a fine, pure and homogeneous oxide mixture suitable for ceramic
processing. The thermal expansion coefficient thus obtained for α-ZrW2O8 is −10.6 × 10−6 °C−1 (50–125 °C) whereas for the β-ZrW2O8 a value of −3.2 × 10−6 °C−1 (200–300 °C) is obtained. The advantages of the use of a sol–gel method is expressed in the very homogeneous end-products.
The paper describes crystallographic data, morphological structure and the thermal expansion properties of the ZrW2O8 material. Moreover, photoluminescence and photochromic properties specific to the precursor gel are described and analyzed.
These effects support our views that the precursors show homogeneity up to nanometer level. 相似文献
53.
54.
F. Weisbuch V.N. Tokarev S. Lazare C. Belin J.L. Bruneel 《Applied Physics A: Materials Science & Processing》2002,75(6):677-680
A new form of matter removal in laser ablation is reported. Polymethylmethacrylate (PMMA) nanofibers are obtained when a PMMA
target is irradiated with a single pulse of a KrF excimer laser, whose beam is sharply imaged on a square of side the order
of 140 μm, so that a strong intensity gradient is produced. The fluence threshold at which fibers appear, 3 J/cm2, is much larger than the ablation threshold, approximately 0.8–1 J/cm2. Above this fluence, the melt depth is then large enough and the temperature profile is such that explosive boiling is obtained.
The model suggests an expulsion of energetic droplets from the intense pressure of the plume to the exterior of the spot.
For the transient melt of a polymeric viscoelastic liquid resulting from UV-laser excitation, such droplets provide the heads
of the jets pulled from the melt bath, giving rise, after solidification, to nanofibers. The speed of fiber spinning is extremely
high (∼800 m/s) and unusual properties of the laser-produced nanofibers may be expected.
Received: 16 April 2002 / Accepted: 17 April 2002 / Published online: 19 July 2002 相似文献
55.
We analyze a discrete-time queueing model where two types of customers, each having their own dedicated server, are accommodated in one single FCFS queue. Service times are deterministically equal to \(s \ge 1\) time slots each. New customers enter the system according to a general independent arrival process, but the types of consecutive customers may be nonindependent. As a result, arriving customers may (or may not) have the tendency to cluster according to their types, which may lead to more (or less) blocking of one type by the opposite type. The paper reveals the impact of this blocking phenomenon on the achievable throughput, the (average) system content, the (average) customer delay and the (average) unfinished work. The paper extends the results of earlier work where either the service times were assumed to be constant and equal to 1 slot each, or the customers all belonged to the same class. Our results show that, in case of Poisson arrivals, for given traffic intensity, the system-content distribution is insensitive to the length (s) of the service times, but the (mean) delay and the (mean) unfinished work in the system are not. In case of bursty arrivals, we find that all the performance measures are affected by the length (s) of the service times, for given traffic intensity. 相似文献
56.
Liliana Cangueiro Jos Antonio Ramos-de-Campos David Bruneel 《Molecules (Basel, Switzerland)》2021,26(21)
Ultrafast lasers micromachining results depend on both the processing parameters and the material properties. The obtained thermal effects are negligible if a good combination of processing parameters is chosen. However, optimizing the processing parameters leading to the required surface quality on a given material can be quite complex and time consuming. We developed a semi-empirical model to estimate the heat accumulation on a surface as a function of the laser fluence, scanning speed and repetition rate. The simulation results were correlated with experimental ones on different materials, and compared with the transient temperature distributions calculated using an analytical solution to the heat transfer equation. The predictions of the proposed model allow evaluating the heat distribution on the surface, as well as optimizing the ultrafast laser micromachining strategy, yielding negligible thermal damage. 相似文献
57.
Herwig Bruneel 《European Journal of Operational Research》1985,21(3):379-386
The paper considers an infinite discrete-time buffer system with one single output channel. Unlike most analyses of such a buffer system, the present study uses a ‘dynamic’ model for the arrival process of data units into the system. More specifically, the distribution of the number of arrivals per discrete time-unit is allowed to fluctuate in time, in a periodical fashion, whereas in classical models this distribution remains the same, as time goes by. The probability generating function of the number of data units in the buffer, at various time instants, is derived under such dynamic arrival conditions. An extended illustrating example, comparing ‘static’ and ‘dynamic’ arrival models, concludes the paper. 相似文献
58.
Present acoustic imaging apparatuses give only a virtual image of the insonified object. Several studies have been conducted in order to pick up the information from such an image, such as holography and computer data processing. These techniques are very involved, and so simpler processing systems have been analysed in our laboratory in order to reconstruct a true image. Our first system used optical processing of the acoustic echo. In this paper, a second, acousto-electronic, system is described, which enables like the first the attainment of very high image rates in the B-scan mode. 相似文献
59.
Herwig Bruneel 《Operations Research Letters》1984,3(3):149-152
The letter considers a discrete buffered system with one randomly interrupted output channel and stochastic interruptions of the arrival stream which are correlated to the output interruptions. The behaviour of this buffer system is studied, and in particular the influence of the correlation is derived. 相似文献
60.
In novel switching approaches such as Optical Burst Switching, the involved buffers can only provide a degenerate waiting
room, with delays restricted to multiples of a basic value, the granularity. Although the resulting performance loss was already
studied analytically, previous work is either limited by the assumption of independent arrivals, or it involves a matrix with
size growing fast with buffer size or arrival process complexity.
Overcoming this, we developed a generic and accurate loss performance model for a degenerate GI/G/1 buffer in discrete time,
that yields results instantly for any constellation of burst sizes, inter-arrival times, granularity, load and buffer size.
This paper presents our model and compares its results to simulations, illustrating the impact of different types of correlation
in the arrival process on loss performance. Our basic model is general and accurate, it can thus serve as a basic tool for
optical switch design.
相似文献