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1.
Mariusz Marć Marek Tobiszewski Bożena Zabiegała Miguel de la Guardia Jacek Namieśnik 《Analytica chimica acta》2015
This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs. 相似文献
2.
3.
V.B. Fainerman V.N. Kazakov S.V. Lylyk A.V. Makievski R. Miller 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):97-102
One of the essential differences in the design of bubble pressure tensiometers consists in the geometry of the measuring capillaries. To reach extremely short adsorption times of milliseconds and below, the so-called deadtime of the capillaries must be of the order of some 10 ms. In particular, for concentrated surfactant solutions, such as micellar solutions, short deadtimes are needed to minimize the initial surfactant load of the generated bubbles. A theoretical model is derived and confirmed by experiments performed for a wide range of experimental conditions, mainly in respect to variations in deadtime and bubble volume. 相似文献
4.
遥感傅里叶变换红外光谱层析技术是一项新的气体分析技术,它可用于构造气体浓度峰图形,定量分析工业污染气体总释放量等方面,随着算法的不断优化,在重构气体在空间的分布方面,遥感傅里叶变换红外光谱层析技术正在不断成长。 相似文献
5.
Active flow-separation control is an effective and efficient mean for drag reduction and unsteady load alleviation resulting
from locally or massively separated flow. Such a situation occurs in configurations where the aerodynamic performance is of
secondary importance to functionality. The performance of heavy transport helicopters and aeroplanes, having a large, and
almost flat, aft loading ramp suffer from the poor aerodynamics of the aft body. Hence, a combined experimental and numerical
investigation was undertaken on a generic transport aeroplane/helicopter configuration. The experimental study provided surface
pressures, direct drag measurements, surface and smoke flow visualization. The baseline flow was numerically analyzed, using
finite volume solutions of the RANS equations. The baseline flow around the model was insensitive to the Reynolds number in
the range it was tested. The flow separating from the aft body was characterized by two main sources of drag and unsteadiness.
The first is a separation bubble residing at the lower ramp corner and the second is a pair of vortex systems developing and
separating from the sides of the ramp. As the model incidence is decreased, the pair of vortex systems also penetrates deeper
towards the centerline of the ramp, decreasing the pressure and increasing the drag. As expected, the ramp lower corner bubble
was highly receptive to periodic excitation introduced from four addressable piezo-fluidic actuators situated at the ramp
lower corner. Total drag was reduced by 3–11%, depending on the model incidence. There are indications that the flow in the
wake of the model is also significantly steadier when the bubble at the lower ramp corner is eliminated. The vortex system
is tighter and steadier when the ramp-corner bubble is eliminated. 相似文献
6.
Analytical approach is presented to the isoperimetric type problems of finding convex figures separated by current hyperplanes. 相似文献
7.
在超声快速制取组织细胞病理切片的过程中,发现激励信号对切片制取效果有明显的影响.为了掌握超声激励信号对组织细胞的影响规律,达到快速制取病理切片的最佳状态,从气泡空化模型入手,通过改变激励信号频率、声压、气泡初始半径和液体黏滞系数等参量,研究了声孔效应中气泡动力学激励机制.数值计算表明:空化泡振动随激励声压增强而升高,随液体黏滞系数增强而减弱;一定频率范围内空化泡振动能保持在膨胀、收缩和振荡的稳定空化状态,存在空化泡稳态振动的最佳激励频率;一定初始半径能保证空化泡产生稳定的振动,存在空化泡稳态振动幅度最大的初始半径.实际操作中,在频率、声压、初始半径和黏滞系数综合作用的若干空化阈内,声孔效应使超声快速法制取细胞组织切片获得最佳效果.
关键词:
声孔效应
超声空化
气泡振动
稳态空化域 相似文献
8.
9.
Melvin Keith Carter 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):191-203
Catalytic air oxidation of the aliphatic hydrocarbons n-decane, hexanes, gasoline and diesel fuel was conducted at ambient temperature with novel iron catalysts. The concentration of n-decane in water was reduced from 1.42 g in 100 ml to 0.07 g in 100 ml in 5 h at room temperature forming carbon monoxide and water by means of intermediate aldehydes. Results of FT–IR and GC–MS analyses demonstrated formation of aldehydes and unsaturated alcohols. Carbon monoxide was detected on catalyst residues and in the vapor phase. The indicated catalytic reaction mechanisms are discussed. 相似文献
10.
《Journal of separation science》2003,26(5):402-408
When nitrated polynuclear aromatic hydrocarbons (NPAH) were recognised as long‐term toxic compounds and were also identified in several anthropogenic emissions and among the by‐products of photochemical smog they became objects of investigation in ambient air in both polluted and clean environments. In Italy the first investigations focussing on atmospheric NPAH were performed in the early eighties and encompassed both the canyon streets and dwelling areas of Rome. Because NPAH were indicated as markers of vehicle emission, new investigations were performed in other cities and also in rural and (nominally) unpolluted locations. In general, the first measurements of NPAH were episodic and could not be assumed to be strictly representative of the sites investigated. In contrast, nowadays consistent data bases on NPAH have been built up and are discussed in the technical literature, so that both neat concentrations and the yearly timed variation of the most important NPAH congeners have been measured in Italian air. Although concentrations of NPAH in air are usually much lower than those of PAH, owing to their very high potency in inducing mutations and tumours NPAH are regarded as having an important health impact on populations living in Italian urban areas. In this regard the genotoxicity of atmospheric aerosols is partly associated with nitrofluoranthenes and nitropyrenes whereas nitronaphthalenes and methylnitronaphthalenes seem to contribute to that of the gaseous organic fraction. Several civic and regional administrations are introducing control of atmospheric NPAH among ways of improving air quality in cities. 相似文献