Wyniki wyszukiwania - BazTech

1

Aerosol physical properties in Spitsbergen's fjords: Hornsund and Kongsfjorden during AREX campaigns in 2014 and 2015

Markuszewski P., Rozwadowska A., Cisek M., Makuch P., Petelski T.

Oceanologia

|

2017

|

No. 59 (4)

460--472

EN

We present results of measurements of aerosol physical properties conducted on board of r/v Oceania during two cruises to the Spitsbergen region in 2014 (AREX 2014) and 2015 (AREX 2015). Measurements of aerosol size distribution, aerosol scattering coefficient and black carbon concentrations were made in two different Spitsbergen fjords: Hornsund and Kongsfjorden. The aerosol size distribution was measured in the size range from 0.09 μm to 47 μm using two aerosol size distribution spectrometers and a standard condensation particle counter. For the scattering coefficient an integrating nephelometer was used. Black carbon concentration was measured by an aethalometer. Temporal variabilities in physical properties of aerosol observed during the AREX 2014 and AREX 2015 campaigns were much higher than the differences between both fjords. The basic factors influencing aerosol conditions were advection and local generation of marine aerosol. In 2015 an episode of smoke advection was observed in both fjords causing an increase in the mean black carbon concentration from 7–12 ng m−3 to about 60 ng m−3, and an aerosol scattering coefficient at 550 nm from 2–4 Mm−1 to 12–17 Mm−1. Moreover, under certain conditions statistically significant gradients in aerosol optical properties were observed along the fjord axis reflecting an impact of mountains surrounding the fjords.

2

Features of Light Scattering by Surface Fractal Structures

Semchuk O., Grechko L., Vodopianov D., Kunitska L.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

|

2009

|

Vol. 13, No 3

199-206

EN

The average coefficient of light scattering by surface fractal structures is calculated within the limits of the Kirchhoff method. A normalized band-limited Weierstrass function is presented for modeling 2D fractal rough surfaces. On the basis of the numerical calculation of the average scattering coefficient, scattering indicatrices diagrams are calculated for various surfaces and falling angles. An analysis of the diagrams leads to the following conclusions: the scattering is symmetric relatively to the plane of fall; the picture becomes complicated when the surface calibration degree is increased; the greatest intensity of a scattering wave is observed in the mirroring direction; there are other directions in which bursts of intensity are observed.

3

Detection and characterization of breast tumours by time-domain scanning optical mammography

Rinneberg H., Grosenick D., Moesta K. T., Wabnitz H., Mucke J., Wübbeler G., Macdonald R., Schlag P.

Opto-Electronics Review

|

2008

|

Vol. 16, No. 2

147-162

EN

The paper gives a short overview of various methods of optical mammography, emphasizing scanning time-domain mammography. The results of a clinical study on time-domain optical mammography are reviewed, comprising 154 patients carrying a total of 102 carcinomas validated by histology. A visibility score attributed to each carcinoma as qualitative measure of tumour detectability indicates acceptable sensitivity but poor specificity for discrimination between malignant and benign lesions. Likewise, a multi-variate statistical analysis yields sensitivity and specificity between 80% and 85% for tumour detection and discrimination with respect to normal (healthy) breast tissue, but values less than 70% for discrimination between malignant and benign breast lesions, being too low to be of clinical relevance. For 87 of the 88 tumours detected retrospectively in both projection optical mammograms, optical properties and tissue parameters were derived based on the diffraction of photon density waves by a spherical inhomogeneity as forward model. Following injection of a bolus of indocyanine green as non-targeted absorbing contrast agent, dynamic contrast-enhanced time-domain optical mammography was carried out on a small number of patients, but no differences in wash-out kinetics of indocyanine green between tumours and healthy breast tissue were observed.

4

Method for measuring optical parameters in weakly absorbing turbid media

Zhao Z., Törmänen M., Myllylä R.

Optica Applicata

|

2004

|

Vol. 34, nr 4

647-656

EN

This article develops a simple, yet effective technique of measuring optical parameters in weakly absorbing turbid samples. Although based on diffusion theory, this technique largely relaxes its strict non-boundary and spot source requirements by choosing a suitable source-detector distance. moreover, the technique is applicable not only to liquid samples, but also to solids or on-line measurements. Experimental results demonstrate that, measured by this method, the reduced scattering coefficients of intralipid suspensions are in good agreement with those obtained by other autors. The paper also reports on the application of this technique to scattering measurements in pulp.

5

Układ dwóch sfer integrujących do badania rozpraszania i absorpcji światła

Liebert A., Łukasiewicz P., Maniewski R.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

|

2000

|

Vol. 6, nr 3-4

73-80

PL

W pracy przedstawiono technikę pomiaru właściwości optycznych z wykorzystaniem układu dwóch sfer integrujących. Pomiar polega na oświetleniu badanej próbki skolimowanym światłem laserowym i oszacowaniu promieniowania reemitowanego przez badaną próbkę, promieniowania transmitowanego oraz transmisji skolimowanej. Pomiary te umożliwiają obliczenie współczynników absorpcji, rozpraszania oraz anizotropii badanego preparatu. Opisano budowę systemu pomiarowego z dwiema sferami integrującymi, uruchomionego w Instytucie Biocybernetyki i Inżynierii Biomedycznej PAN. Omówiono zasady prowadzenia pomiarów, wskazano na źródła błędów. Zaprezentowano wyniki pomiarów mleka jako płynu o właściwościach optycznych zbliżonych do tkanek żywych. Stwierdzono, że jest możliwe stosowanie roztworów mleka z dodatkiem absorbera do budowy fantomów tkanek.

EN

The measurements of optical properties of the tissue is important for development of optical diagnostic methods. In this paper we present the technique of optical properties measurement with the use of double-integrating spheres system. The measurement of total reflectance, total transmittance and collimated transmittance allows to calculate scattering, absorption and anisotropy coefficients. General principles of the measurement were presented. Also the sources of errors were pointed out. The double-integrating spheres system constructed in the Institute of Biocybernetics and Biomedical Engineering was described. The measurements of optical properties of the milk as a medium optically similar to human tissue were carried out. It was observed that the milk solutions with absorber allow to build optical phantoms of the human tissues.