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61.
Building ventilation of an enclosure with a single opening is affected not only by the steady mean effect of air pressures and temperatures around and within the building, but also by the turbulent nature of the wind. To improve understanding of the physical phenomena causing air exchange through a single opening, models to simulate the indoor pressure resulting from fluctuations of the wind-induced outdoor pressure are analysed and experimental requirements for model validation are discussed. The influence of the dimensions of the opening and the volume of the room on the time constant are discussed and the numerical constraints of the non-linear low-pass filter modelling for infiltration are highlighted. In particular the frequency limits for data logging or simulations are dependent on this time constant.
A method is proposed to avoid the oscillation of the simulated indoor pressure for the case of under-sampling which frequently occurs because of the limitation of data acquisition rates. The need for further work on this problem is discussed. 相似文献
62.
63.
Ahmed El Oualkadi Jean-Marie Paillot Herv Guegnaud Rachid Allam 《AEUE-International Journal of Electronics and Communications》2005,59(6):352-358
A new RF switched capacitor bandpass filter and its command circuit made up of a ring voltage controlled oscillator with ‘XOR’ gates are proposed. Implemented in a standard CMOS technology, this circuit is intended to be used in a subset of professional mobile phone applications [380–520 MHz]. Experiments carried out on a prototype show a tunable center frequency range of 260 MHz [240–500 MHz], with a quality factor that can be as high as 300. 相似文献
64.
Mehdi Ghodsi Jacquy Detournay Jean-Marie Schrobiltgen Georges Naessens 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1987,37(2):133-143
Thermal treatment in an oxidizing atmosphere of a mixture of raw blende (ZnS) and copper(II) oxide enhanced the formation of a mixed ferrite phase at temperature about 600°C. The composition established at 900°C was approximately (0.8 ZnO · 0.2 CuO)Fe2O3. For the mixture ZnS–CuO, with 5 to 15% CuO by weight, less than 15% copper was involved in the formation of the spinel phase. The increasing copper content in the mixture, roasted above 1000°C, favoured solubilization of iron, even in a weakly acid medium. 相似文献
65.
Jean-Marie Dufour 《时间序列分析杂志》1981,2(3):117-128
Abstract. A family of linear rank statistics is proposed in order to test the independence of a time series, under the assumption that the random variables involved have symmetric distributions with zero medians, without the standard assumptions of normality or identical distributions. The family considered includes analogues of the sign. Wilcoxon signed-rank and van der Waerden tests for symmetry about zero and tables constructed for these tests remain applicable in the present context. The tests proposed are exact and may be applied to assess serial dependence at lag one or greater. The procedures developed are illustrated by a test of the efficiency of forward exhange rates as predictors of future spot rates during the German hyperinflation. 相似文献
66.
Brigitte Wyhowski de Bukanski Jean-Marie Degroodt Hedwig Beernaert 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1988,187(3):242-245
Summary A procedure for the identification of sulphonamides in edible animal tissues by two-dimensional high-performance thin-layer chromatography is described. Sixteen sulphonamides can be detected at an absolute level of 10 ng. The absolute detection limit of the sulphonamide standards is 1 ng. After extraction of the sulphonamides with chloroform/acetone, the acidified extract is concentrated and purified using a cation-exchange solid phase extraction column. The column is treated with ammonia vapour and the sulphonamides are then eluted with methanol. Blank samples of edible animal tissues spiked with sulphonamides (frequently used in Belgium) result in very good separation.
Identifizierung von sulfonamiden in geweben von schlachttieren mittels zweidimensionaler hochleistungsdünnschichtchromatographie
Zusammenfassung Eine Methode zur Identifizierung von Sulfonamiden in Geweben von Schlachttieren mittels zweidimensionaler Hochleistungsdünnschichtchromatographie wird beschrieben. 16 Sulfonamide können identifiziert werden, wobei die absolute Empfindlichkeitsgrenze bei 10 ng liegt. Die absolute Nachweisgrenze für die Referenzsubstanzen liegt bei 1 ng. Nach Extraktion der Sulfonamide mit Chloroform-Aceton wird die angesäuerte Extraktlösung auf einer Kationenaustausch-Extraktionssäule eingeengt und gereinigt. Die Säule wird mit Ammoniakdämpfen behandelt und die Sulfonamide werden anschliessend mit Methanol eluiert. Die den Gewebeextrakten zugefügten in Belgien häufig verwendeten Sulfonamide konnten sehr gut voneinander getrennt werden.相似文献
67.
Jean-Pierre Bastide Bernard Bonnetot Jean-Marie Létoffé Pierre Claudy 《Materials Research Bulletin》1980,15(12):1779-1787
The structural relationships in magnesium hydride have been studied under P-T conditions up to 80 kbar and 900°C. α-MgH2 of rutile structure in normal conditions transforms into two new phases under high pressures : β-MgH2 and γ-MgH2 respectively with a hexagonal (pseudocubic) and an orthorhombic unit-cell structure·β-MgH2 maybe related to a fluorite type form (with an eight-coordination for Mg) transforming when releasing pressure into γ-MgH2 of α-PbO2 type (with a six-coordination for Mg). The density of α-MgH2 and γ-MgH2 are very similar but the density of the β-MgH2 fluorite form is some 25 % greater than that of the rutile type. Thus MgH2 seems to exhibit under high pressure conditions the typical behavior of number of rutile type compounds MX2 such as fluorides or oxides. 相似文献
68.
Multidrug transporter proteins promote the active transmembrane efflux of noxious drugs, thereby decreasing their accumulation in the intracellular medium and reducing their therapeutic efficiency. Expression of such proteins drastically reduces the efficiency of chemotherapeutic treatments against cancer and various infectious diseases. To overcome major difficulties related to the crystallization of membrane proteins, other experimental approaches have been developed to gain information on the structural changes involved in drug transport. We examine here and illustrate with a few examples how infrared and fluorescence spectroscopy can provide new insights into the structure of the membrane domains of multidrug transporters in particular. Such domains contain the drug-binding site(s) and mediate the passage of substrates across the cell membrane. 相似文献
69.
Lagarde F Tusseau-Vuillemin MH Lessard P Héduit A Dutrop F Mouchel JM 《Water research》2005,39(19):4768-4778
This paper presents a methodology for assessing the variability of biodegradable chemical oxygen demand (COD) fractions in urban wastewaters. Thirteen raw wastewater samples from combined and separate sewers feeding the same plant were characterised, and two optimisation procedures were applied in order to evaluate the variability in biodegradable fractions and related kinetic parameters. Through an overall optimisation on all the samples, a unique kinetic parameter set was obtained with a three-substrate model including an adsorption stage. This method required powerful numerical treatment, but improved the identifiability problem compared to the usual sample-to-sample optimisation. The results showed that the fractionation of samples collected in the combined sewer was much more variable (standard deviation of 70% of the mean values) than the fractionation of the separate sewer samples, and the slowly biodegradable COD fraction was the most significant fraction (45% of the total COD on average). Because these samples were collected under various rain conditions, the standard deviations obtained here on the combined sewer biodegradable fractions could be used as a first estimation of the variability of this type of sewer system. 相似文献
70.
AbstractThis study considers the decay heat removal through passive systems (i.e., natural convection) in the pool-type experimental reactor MYRRHA (SCK?CEN). The low velocities associated with natural convection may cause a degradation of the thermal mixing in the upper plenum of the reactor: buoyancy dominated phenomena, such as stratification, buoyant jets or convective cells may occur. The large temperature gradients associated with these phenomena may induce thermal loads on the structure, compromising its integrity. The objectives of this work are, in order, (1) achieving an understanding of the fluid mechanics leading to the formation of thermal gradients in the upper plenum and (2) mitigating the temperature gradients the upper plenum’s geometry. The methodology chosen to address the problem is experimental. A ''two-dimensional'' water facility modeling a slab of the reactor's primary loop was designed. Simultaneous measurements of velocity and temperature were performed in the model's buffer tank using thermocouples and innovative optical imaging techniques. It was observed that vertical thermal gradients develop in the tank because of the combined effect of stratification and advection. Important reductions of local gradients were observed when changing porosity and position of upper plenum’s buffer plates. 相似文献