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1.
A. Ankilov A. Baklanov M. Colhoun K. -H. Enderle J. Gras Yu. Julanov D. Kaller A. Lindner A. A. Lushnikov R. Mavliev F. McGovern T. C. O'Connor J. Podzimek O. Preining G. P. Reischl R. Rudolf G. J. Sem W. W. Szymanski A. E. Vrtala P. E. Wagner W. Winklmayr V. Zagaynov 《Atmospheric Research》2002,62(3-4)
During an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (IAMAS-IUGG), 10 instruments for aerosol number concentration measurement were studied, covering a wide range of methods based on various different measuring principles. In order to investigate the detection limits of the instruments considered with respect to particle size, simultaneous number concentration measurements were performed for monodispersed aerosols with particle sizes ranging from 1.5 to 50 nm diameter and various compositions.The instruments considered show quite different response characteristics, apparently related to the different vapors used in the various counters to enlarge the particles to an optically detectable size. A strong dependence of the 50% cutoff diameter on the particle composition in correlation with the type of vapor used in the specific instrument was found. An enhanced detection efficiency for ultrafine hygroscopic sodium chloride aerosols was observed with water operated systems, an analogous trend was found for n-butanol operated systems with nonhygroscopic silver and tungsten oxide particles. 相似文献
2.
J. L. Gras A. Adriaansen R. Butler B. Jarvis P. Magill B. Lingen 《Journal of Atmospheric Chemistry》1985,3(1):93-106
Condensation nucleus (CN) concentrations have been measured at Mawson (67.6°S, 62.9°E) since mid 1981. Weekly median concentrations have an annual cycle with a maximum of around 300 to 400 cm-3 in summer and a minimum of a few tens of particles per cm-3 in winter. In this respect Mawson behaves very much like an Antarctic continental location. Preliminary measurements of the size distribution of CN particles taken over a nine month period suggest a seasonal change in typical particle radius from around 0.01 m in winter to around 0.04 m in summer. Diurnal variation in the CN concentration is generally very weak and does not show any systematic relation to the pronounced diurnal variation in wind-speed at Mawson.Department of Science, Antarctic Division 相似文献
3.
This paper presents a three-dimensional constitutive model for natural clay that includes creep, anisotropy and structure, as well as a theoretical means to estimate the range for anisotropy- and structure-related parameters, as needed for parameter optimisation. Creep-SCLAY1S is an extension of the Creep-SCLAY1 model proposed by Sivasithamparam et al. (Comput Geotech 69:46–57, 2015) which includes the effects of bonding and destructuration. The model needs 14 model parameters, of which five are similar to those used in the modified Cam–Clay model. A method is developed to quantify the range for the three parameters related to structure and anisotropy that cannot be derived directly from experimental data. The theoretically derived range compares favourably with the values found in the literature. As a result, the model now can be used with more confidence, enabling sensitivity analysis and systematic parameter derivation with optimisation techniques. 相似文献
4.
Analysis of the Upper Cretaceous stratigraphy of the Peel Block reveals the basin development of the block to have been influenced by both the inversion of the Roer Valley Graben and Central Netherlands Basin, and the overall Late Cretaceous transgression. Sediments of Santonian to Danian age were deposited on the block. These sediments are compared with the detailed lithostratigraphy of southern Limburg, where Late Cretaceous strata are exposed. Four successions can be recognised in southern Limburg. The two oldest successions, the Santonian Oploo Formation (new name, proposed in the present contribution) and the mainly Early Campanian Vaals Formation, are restricted to the central and northern parts of the block. These siliciclastic formations were deposited under the influence of inversion of the Roer Valley Graben and the Central Netherlands Basin, as well as under the influence of a rising sea level. Towards the north, sands of the Oploo Formation grade into marls and chalks of the Ommelanden Formation. The two youngest successions comprise the largely Late Campanian to Maastrichtian Gulpen and Maastricht Formations and the Danian Houthem Formation. These chalk formations were deposited under the influence of regional subsidence during a sea-level highstand. Subsequent to deposition of the Houthem Formation, a regional regression triggered a change from shallow-marine carbonate to paralic siliciclastic deposition. 相似文献
5.
RAMON APARICIO 《地理学报(英文版)》1988,(Z1)
SEXIA is an expert system that uses a new methodological approach to identify foods,particularly oliveoils according to varieties,olive zones and denominations of origin.The methodological approachprovides identification tools,associating a confidence degree or a belief interval to the final hypotheses.The certainty factor and the Dempster-Shaffer theory,with some modifications,have been implementedin SEXIA.The computer can work with 50 chemical parameters whose data have previously beenacquired by the food analyst via a dialogue in the Spanish language.The system has been verified with144 olive oil samples.In this paper some results obtained for distinguishing the Arbequina variety fromother varieties using SEXIA and the BMDP stepwise discriminant analysis program are presented.Finally,promising directions for future research are suggested. 相似文献
6.
The aim of this work is to present a statistical study of several parameters (variables) that define sunspot groups. These variables include maximum area, growth and decay times, as well as the evolution families, and solar-cycle phase the groups belong to. We classified group types based on the Zurich classification, which allows us to define a set of families based on their evolution patterns. The time variation of the area of a group was also studied, and a relationship between the maximum area and the growth and decay times was sought. Another study was carried out to find the correlation among different characteristics of the groups, as well as how the probability of a certain value of decay time can vary depending on morphological characteristics defined by these variables. Thus, a program based on a weight matrix combining the variables necessary to classify a group, together with the calculation of the probability for a specific event, has been produced. This approach allows us to predict the future behavior of a group from its historical evolution. 相似文献
7.
Three “standard” Nolan–Pollak (N–P) and a modified N–P design condensation nucleus (CN) counters were included in the Vienna Workshop on Intercomparison of Condensation Nuclei and Aerosol Particle counters. These counters came from diverse backgrounds, namely programs in USA, Europe and Australia. In this work, principles of the operation and previous history of calibration of the N–P expansion counter are briefly reviewed and comparisons between the particular counters used in the workshop are presented and discussed. Counting agreement was found to be very good between the N–P counters, typically better than ±12% for a range of aerosol sizes and compositions from a minimum diameter of 4 nm. The independently calibrated GIV CNC-440 (modified N–P type counter) also agreed well with the N–P counters. The minimum size sensitivity of the N–P counter was examined showing a lower detection limit for insoluble (Ag) particles of around 2.6±0.3 nm diameter. 相似文献
8.
A simple and rapid method for the detection and extraction of oxolinic acid, flumequine, florfenicol and oxytetracycline from marine sediments was developed and validated. The analytes were extracted from the marine sediment using a solution of oxalic acid diluted in methanol with sonication before detection by HPLC using a diode-array detector (florfenicol and oxytetracycline) and fluorescence (oxolinic acid and flumequine). The quantification limits (QL) were 100 ng/g for oxytetracycline and florfenicol and 5 ng/g for oxolinic acid and flumequine. The coefficients of variation of the repeatability and intermediate precision were less than 10% in all of the analytes. The calibration curves were linear between 50 and 500 ng/ml for oxytetracycline and florfenicol and 1 and 20 ng/ml for oxolinic acid and flumequine. The recuperation rate for the analytes was above 86%. 相似文献
9.
A. Downey J. D. Jasper J. J. Gras S. Whittlestone 《Journal of Atmospheric Chemistry》1990,11(1-2):43-68
Radon and particle concentrations obtained at Macquarie Island, halfway between Australia and Antarctica, and on Tasmania's north-west coast at Cape Grim during 1987 are examined. Four-day trajectories based on 12 hourly analyses over the Australian region are used to explore the transport of continental material across the Southern Ocean. This study suggests that at least 25% of the variance of radon concentration at Macquarie Island can be accounted for by transport from the Australian continent. Trajectories at intervals of one hour are used to demonstrate the agreement between episodes of trajectories passing over land and episodes of elevated radon and particle concentration. Wind roses of percentage probability of various levels of radon and particle concentration are compared with back trajectories for their accuracy in depicting episodes of continental air incursion. 相似文献
10.
Seasonal variations in total particle concentrations at five remote Southern Hemisphere sites in Samoa, Tasmania and Antarctica are compared. The dominant particle production mechanism is deduced to be photochemical, with concentrations dictated by the availability of radiation in the eight months centred on the winter solstice. There is little variation with latitude in the mean summer concentrations. The middle troposphere is shown to act as an important reservoir of photochemically-produced particles in Tasmania and probably in the Antarctic. It is suggested that primary-particle production is mainly through the oxidation of dimethyl sulphide and that these particles then act as centres of condensation for sulphuric acid formed by the oxidation of sulphur dioxide. 相似文献