Wyniki wyszukiwania - BazTech

1

Modelling of seawater polluted by light and heavy crude oil droplets

Rudź K., Darecki M., Toczek H.

Journal of KONES

|

2012

|

Vol. 19, No. 2

473-480

EN

Significant amounts of crude oil transported from offshore fields to the refineries using tankers or pipelines, demand increased control of seawater pollution. Tanker accidents resulting in oil spills drive much attention, as they influence local marine life and coastal industry. However, the most significant annual amount of crude oil enters the sea in the form of oilin- water emulsion as a result of standard tanker operations, offshore oil extraction and daily work of refineries. Many branches of science are challenged to provide new methods for oil detection, less expensive, more sensitive and more accurate. Remote satellite or airborne detection of large oil spills is possible using joint techniques as microwave radars, ultraviolet laser fluorosensors and infrared radars. Some methods are capable to deal with oil streaks detection and estimation of oil thickness. Although there is currently, no method to detect small concentration of oil droplets dispersed in seawater. Oil droplets become additional absorbents and attenuators in water body. They significantly change seawater inherent optical properties, which imply the change of apparent optical properties, detectable using remote sensing techniques. To enable remote optical detection of oil-in-water emulsion, a study of optical properties of two types of crude oil was conducted. Radiative transfer theory was applied to quantify the contribution of oil emulsion to remote sensing reflectance (Rrs). Spectra of Rrs from in situ measurements in Baltic Sea were compared to Rrs spectra of seawater polluted by 1 ppm of crude oil emulsion, collected using radiative transfer simulation. The light crude oil caused a 9-10% increase of Rrs while the heavy one reduced Rrs up to 30% (model accuracy stayed within 5% for considered spectral range). Results are discussed concerning their application to shipboard and offshore oil content detection.

2

Emulsified fuels of machine origin in seawater - a contribute to remote detection

Rudz K.

Journal of KONES

|

2011

|

Vol. 18, No. 2

385-390

EN

Development of industry and trade in the last few decades caused a huge increase in the pollution of the world's oceans. Substantial contributors to marine pollution come with the rivers from land-based sources including the by-products of industry, run-off from agriculture activities such as biocides as well as effluents from urban areas. Moreover, a significant amount of marine pollution is caused by shipping and maritime activities. The operation of ship plants gives a real possibility for engine oils and fuels to reach the marine environment. Discharge waters contain a certain amount of petroleum derivatives in the form of dispersed droplets (oil-in-water emulsion). The presence of oil emulsion cause measurable changes in the optical properties of seawater. It is conceptually possible to detect these changes using a standard radiance or irradiance reflectance meter. Hence, a set of radiative transfer simulation has been carried out. This paper presents a computed photon trace simulation based on the Monte Carlo code, applied to the marine environment. The results are presented as reflectance spectra for the models of Baltic Sea and ocean water both pure and polluted by oil emulsion. It is shown that even small amounts of petroleum pollution rise the values of irradiance reflectance and cause a spectral shift by certain conditions. A possibility for remote evaluation of oil pollution is discussed as well as the perspective for improving the interpretation of shipboard and offshore light field analyses.

3

Emulsified fuels of machine origin in seawater - a contribute to remote detection

Rudz K.

Journal of KONES

|

2011

|

Vol. 18, No. 3

375-381

EN

Development of industry and trade in the last few decades caused a huge increase in the pollution of the world's oceans. Substantial contributors to marine pollution come with the rivers from land-based sources including the by products of industry, run-off from agriculture activities such as biocides as well as effluents from urban areas. Moreover, a significant amount of marine pollution is caused by shipping and maritime activities. The operation of ship plants gives a real possibility for engine oils and fuels to reach the marine environment. Discharge waters contain a certain amount of petroleum derivatives in the form of dispersed droplets (oil-in-water emulsion). The presence of oil emulsion cause measurable changes in the optical properties of seawater. It is conceptually possible to detect these changes using a standard radiance or irradiance reflectance meter. Hence, a set of radiative transfer simulation has been carried out. This paper presents a computed photon trace simulation based on the Monte Carlo code, applied to the marine environment. The results are presented as reflectance spectra for the models of Baltic Sea and ocean water both pure and polluted by oil emulsion. It is shown that even small amounts of petroleum pollution raise the values of irradiance reflectance and cause a spectral shift by certain conditions. A possibility for remote evaluation of oil pollution is discussed as well as the perspective for improving the interpretation of shipboard and offshore light field analyses.

4

Possibilities of applying the backward ray tracing method for investigations and simulations of radiative heat transfer in systems with optically active media

Gawroński M.

Poznan University of Technology Academic Journals. Electrical Engineering

|

2010

|

No. 61

189-196

EN

In the article the selected methods of modeling radiative energy transfer in participating media were compared. Calculations were performed for furnace chamber filled an absorbing-emmiting gas. Accuracy and duration of calculations using different methods were compared.

5

The temperature - and stress fields of valves of IC engine

Jaskólski J., Krzyżak R.

Journal of KONES

|

2007

|

Vol. 14, No. 3

245-252

EN

The paper concerns building up one exhaust valve of composite-steel and two intake ceramics-steel valves of a hypothetical adiabatic engine. The input temperatures were computed using three diverse FORTRAN95 programs, solving a shortened optical integral equation with radiative transfer, transient differential equation while starting and switching off the engine and a rod like diff. Equation with 'progonka' (Thomas) solution. The ANSYS11 programme was fed up with the output of the programs. It turns out that, generally, a mineralogical, crystal-chemical approach to the joining of materials results in stresses known from the common metal engines. Such problems as CTE enhancing (partly hypothetical) by means of doping the anionic compounds by cationic ones, swelling of structures, compressibility versus coefficient of thermal expansion (CTE) , compatibility of crystal motifs while joining, thermal shock resistance, switching the bonds, mechanical longevity, radiation protection etc were addressed. It turns out that true nature of the temperature and stress field, especially of the exhaust valve is closer to the FORTRAN temperature computation than, e.g. From the heat film coefficients (ANSYS11).

6

A thermomechanical aspect of the ceramic-capped piston of hypothetical adiabatic diesel engine

Jaskólski J., Krzyżak R.

Journal of KONES

|

2006

|

Vol. 13, No. 2

169-177

EN

The paper concerns a hypothetical Al.-alloy piston coated (capped) first by labradore and then capped by YSZ. The labradore, a member of the feldspar group is deemed thermal-shock resistant, the YSZ(PSZ) can be shock-resistant, but the outcome of the two with the Al.-alloy is not known. The analysis were made in two ways by ANSYS 10.0, as wholly isotropic materials and (second) labradore treated as wholly orthotropic one as basing on a designed texture. The above programme was fed up by the FORTRAN95-outcome of temperatures and the other B.C.’s.The temperatures between the ceramics and the alloy (except one node!!, the FORTRAN) are ( from the above two procedures), 222.63 to 270-300 graduate C, at the first groove are about 290 graduate C, and, surely lower (orthotropic). The relatively low (to ceramic) inner tensile stresses are embraced by the compressive ones from all the sides. The only problem is the-alloy bearing capacity at some sections at the ceramic boundary (and only there). But, it was the aim of the work to stick ceramics there.The dangerous stresses can occur at the pin .The ‘orthotropic ‘ results are better than the ‘iso’-ones and more true.. Taking into account that the real loading will be lower (porosity of the ceramics, the mass and the possible subtraction of stresses, i.e. those ceramic-production-confined ones) , the laboratory production of the piston appears worth.

7

Analysis of luminous flux transfer through a conical ring-core light guide

Dorosz J., Dybczyński W.

Optica Applicata

|

2004

|

Vol. 34, nr 3

349-364

EN

Analysis of luminous flux transfer through a conical ring-core light guide is presented. Three optical guides of this kind are the main elements of an original instrument for measurement of the luminance distribution in the field of view constructed by the authors. It was found that in the case of the output surface perpendicular to the symmetry axis of the cone having vertical angles greater than 50° the luminous flux is not transmitted through this kind of light guide. The conical output surface with great vertical angle considerably improves the process of transfering the luminous flux through a conical ring-core light guide. Replacing a flat outlet surface of the light guide by a conical one makes the transferred luminous flux more uniform to some extent.

8

New materials and ideas to be used in adiabatic engines

Jaskólski J., Krzyżak R.

Journal of KONES

|

2004

|

Vol. 11, No. 1-2

288-294

EN

This note concerns several topics. Firstly, a review of some less-known topics regarding the contemporary knowledge on TBC and piston caps is given. Then, it turns out that almost unknown New Periodic System of Elements can be of assistance to predict several properties of new TBC materials. Theoretically, there exist a possibility to join Si-AL-piston alloy with yttria-stabilised zirconia (and the like) by means of feId spars (plagioclase). The latter do not attain to melting temperature and can be arrested within the alloy. A shortened integral optical equation in the manner of inverse problem was used to compute the temperature drop accros the piston cap's layers. The YSZ layer operating in this hypothetical engine gave 517.5 graduate K drop, whereas the feldspar gave about 100-50graduate K temperature drop per mm. This arrangement would give minimised radiation and more or less 'cold' engine(piston). Perhaps, oxides of the thalium-sesquioxide-type structure would be better to stick to metal than the commonly used ones.

9

Range dependent radiation leakage from thin scattering columns due to multiple small angle scatter

Kravtsov Y. A., Apresyan L. A., Asatryan A. A., Chrzanowski J., Kirkiewicz J.

Optica Applicata

|

2003

|

Vol. 33, nr 2-3

293-305

EN

The phenomenon of range dependent radiation leakage from thin random columns caused by small angle multiple scatter is analysed. On the basis of modified Born approximation (Ishimaru, 1978; Apresyan and Kravtsov, 1996), it is shown that extinction coefficient, describing energy leakage due to multiple scatter on large (as compared to wavelength) inhomogeneities, first increases proportionally to distance z1/2 and then saturates on the level which might significantly exceed conventional extinction coefficient, connected with large angle light scatter on small inhomogeneities. The effect might be observed in many physical systems, for example, in a tube filled with water emulsion or suspension, containing small and large particles. The phenomenon may be helpful in distinguishing the contribution of small and large inhomogeneities to total extinction

10

Effect of distribution of electromagnetic field inside optical fibres on their luminous flux

Nikołajew A., Dorosz J.

Optica Applicata

|

2003

|

Vol. 33, nr 1

205-212

EN

A method for calculation of luminous flux emitted by the front surface of a fibre was proposed. A step-index fibre was considered. Calculations were based upon known electromagnetic field distribution inside the core represented by analytical equations. Particular modes were shown as the superposition of linear polarized plane waves. Light refraction on the fibre front surface was also taken into consideration. It was found that spatial distribution of the luminous flux of a particular fibre depended on its normalized frequency

11

Analysis of the spatial distribution of luminous intensity at the fibre output

Nikołajew A., Dorosz J.

Optica Applicata

|

2003

|

Vol. 33, nr 4

575-581

EN

A method based on weakly guiding approximation which allows calculation of luminous intensity in step-index fibre was proposed. The calculation shows that spatial distribution of luminous intensity is rotationally symmetrical and has a discrete character. The quantity and values of emission angles depend on the normalized frequency of a fibre. Values of luminous intensity depend on the position and radiant power distribution of the light source.

12

SeaWiFS-derived products in the Baltic Sea : performance analysis of a simple atmospheric correction algorithm

Bulgarelli B., Mélin F., Zibordi G.

Oceanologia

|

2003

|

No. 45 (4)

655-677

EN

The accuracy analysis of an approximate atmospheric correction algorithm for the processing of SeaWiFS data has been investigated for the Baltic Sea. The analysis made use of theoretical radiances produced with the FEM radiative transfer code for representative atmosphere-water test cases. The study showed uncertainties in the determination of the aerosol optical thickness at 865 nm and of the A*ngström exponent lower than š 5% and š 10%, respectively. These results were confirmed by the analysis of 59 match-ups between satellite-derived and in situ measurements for a site located in the central Baltic. Because of the relatively high yellow substance absorption, often combined with the slanted solar illumination, the retrieval of the water-leaving radiance in the blue part of the spectrum appeared to be highly degraded, to the extent that almost no correlation was found between retrieved and simulated values. Better results were obtained at the other wavelengths. The accuracy in the estimation of the remote sensing reflectance ratio R35 decreased with diminishing chlorophyll a concentration and increasing yellow substance absorption, ranging between š 7% and š 47%. The propagation of R35 uncertainties on chlorophyll a estimation was quantified. Keeping the same atmosphere-water conditions, the atmospheric correction scheme appeared sensitive to seasonal changes in the Sun zenith.

13

Inverse methods in hydrologic optics

Gordon H. R.

Oceanologia

|

2002

|

No. 44 (1)

9-58

EN

Methods for solving the hydrologic-optics inverse problem, i.e., estimating the inherent optical properties of a water body based solely on measurements of the apparent optical properties, are reviewed in detail. A new method is developed for the inverse problem in water bodies in which fluorescence is important. It is shown that in principle, given profiles of the spectra of up- and downwelling irradiance, estimation of the coefficient of inelastic scattering from any wave band to any other wave band can be effected.