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EN
The aim of this study was to investigate the light transfer through sea ice with a focus on bio-optical substances both in fast ice and in the drift ice zones in the northern Baltic Sea. The measurements included snow and ice structure, spectral irradiance and photosynthetically active radiation below the sea ice. We also measured the concentrations of the three main bio-optical substances which are chlorophyll-a, suspended particulate matter, and coloured dissolved organic matter (CDOM). These bio-optical substances were determined for melted ice samples and for the underlying sea water. The present study provides the first spectral light transfer data set for drift ice in the Baltic Sea. We found high CDOM absorption values typical to the Baltic Sea waters also within sea ice. Our results showed that the transmittance through bare ice was lower for the coastal fast ice than for the drift ice sites. Bio-optical substances, in particular CDOM, modified the spectral distribution of light penetrating through the ice cover. Differences in crystal structure and the amount of gas inclusions in the ice caused variation in the light transfer. Snow cover on ice was found to be the dominant factor influencing the light field under ice, confirming previous studies. In conclusion, snow cover dominated the amount of light under the ice, but did not modify its spectral composition. CDOM in the ice absorbs strongly in the short wavelengths. As pure water absorbs most in the long wavelengths, the light transfer through ice was highest in the green (549-585 nm).
PL
Współczesne systemy komórkowe bazują na technologii LTE, czyli standardu czwartej generacji (4G). Obecnie trwają pracę nad zakończeniem standardu definiującego systemy piątej generacji (5G), które będą implementowane w najbliższych latach. Nowa generacja systemów dotyczy już nie tylko sieci komórkowych ale również innych systemów łączności bezprzewodowej, od Internetu rzeczy, przez sieci Wi-Fi, po łączność satelitarną. Technologie 5G zrewolucjonizują całą łączność bezprzewodową zapewniając jednocześnie kompatybilność wsteczną. Jednymi z kluczowych technologii 5G są efektywne technologie antenowa, tzn. massive-MIMO oraz elektroniczne sterowanie wiązką. Ich zastosowanie w przyszłych stacjach bazowych makro-komórek pozwoli na przestrzenne zdywersyfikowanie zasobów radiowych. Technologie te pozwalają na generowanie bardzo wąskich wiązek radiowych, dzięki czemu zapewniają przestrzenną filtrację składowych sygnału emitowanych przez antenę nadawczą oraz docierających do anteny odbiorczej w środowiskach wielodrogowych. W artykule przedstawiono problematykę minimalizacji zjawiska dyspersji kątowej w sieciach 5G na bazie badań symulacyjnych. W tym celu wykorzystano wieloeliptyczny model propagacyjny.
EN
Modern cellular systems are based on the LTE technology, i.e., fourth generation (4G) standard. Currently, works on the standard defining fifth generation (5G) systems is underway, which will be implemented in the coming years. The new system-generation applies not only to cellular networks but also to other wireless communication systems, from the Internet of Things, through Wi-Fi networks, to satellite communications. 5G technologies will revolutionize all wireless connectivity while providing backward compatibility. One of the key 5G technologies are efficient antenna technologies, i.e., massive-MIMO and beamforming. Their use in future macro-cell base stations will allow spatial multiplexing of radio resources. These technologies allow the generation of radio narrow-beams, thus providing spatial filtration of the signal components emitted by the transmitting antenna and reaching the receiving antenna in multipath environments. The paper presents issues of minimizing the angular dispersion in 5G networks based on simulation studies. For this purpose, a multielliptical propagation model is used.
EN
Acoustical Driving Forces (ADF), induced by propagating waves in a homogeneous and inhomogeneous lossy fluid (suspension), are determined and compared depending on the concentration of suspended particles. Using integral equations of the scattering theory, the single particle (inclusion) ADF was calculated as the integral of the flux of the momentum density tensor components over the heterogeneity surface. The possibility of negative ADF was indicated. Originally derived, the total ADF acting on inclusions only, stochastically distributed in ambient fluid, was determined as a function of its concentration. The formula for the relative increase in ADF, resulting from increased concentration was derived. Numerical ADF calculations are presented. In experiments the streaming velocities in a blood-mimicking starch suspension (2 μm radius) in water and Bracco BR14 contrast agent (SF6 gas capsules, 1 μm radius) were measured as the function of different inclusions concentration. The source of the streaming and ADF was a plane 2 mm diameter 20 MHz ultrasonic transducer. Velocity was estimated from the averaged Doppler spectrum obtained from originally developed pulsed Doppler flowmeter. Numerical calculations of the theoretically derived formula showed very good agreement with the experimental results.
PL
W pracy przeprowadzono analizę wpływu wybranych zaburzeń początkowych na rozrzut wszerz naddźwiękowego pocisku moździerzowego powstałego w ramach programu RAK AMUNICJA. W pierwszej części pracy wytypowano czynniki mogące mieć wpływ na rozrzut wszerz pocisków moździerzowych. Analizowano wpływ parametrów takich jak: początkowa prędkość poprzeczna pocisku, początkowy kąt odchylenia pocisku, początkowa prędkość kątowa odchylenia pocisku oraz krótkotrwały podmuch wiatru poprzecznego. Następnie oszacowano możliwe wartości zaburzeń tych parametrów i wykonano dla tych wartości obliczenia przy prędkości początkowej v0=500 m/s. Obliczenia prowadzono za pomocą modelu lotu o pięciu stopniach swobody opracowanego dla pocisków moździerzowych. Wyniki obliczeń porównano z rezultatami uzyskanymi analitycznie za pomocą wzoru opisującego wartość podrzutu aerodynamicznego przedstawionego w literaturze. W końcowej części pracy przedstawiono wnioski.
EN
Influence of selected initial disturbances into the lateral dispersion of a supersonic mortar projectile, developed in the frame of RAK MUNITIONS program, is analysed in the paper. In the first part of the paper some factors which may influence the lateral dispersion of mortar projectiles are indicated. Such parameters of the projectile as initial lateral velocity, initial angle of yaw and initial velocity of the yaw angle, and an unexpected lateral gust of wind were analysed. In the next step the possible values of disturbances for these parameters were estimated to perform the calculations for these values at the muzzle velocity of v0=500 m/s. The calculations were performed by using a model of flight with five degrees of freedom which was developed for the mortar projectiles. The results of calculations were compared with the analytical results received with a relation presented in the literature for values of aerodynamic jump. The conclusions are presented in the final part of the paper.
EN
The size and shape of biological particles are important parameters allowing discrimination between various species. We have studied several aerosols of biological origin such as pollens, bacterial spores and vegetative bacteria. All of them presented different morphology. Using optical size and shape analyser we found good correlation between light scattering properties and actual particle features determined by scanning electron and fluorescence microscopy. In this study, we demonstrated that HCA (Hierarchical Cluster Analysis) offers fast and continuous bioaerosol classification based on shape and size data matrices of aerosols. The HCA gives an unequivocal interpretation of particle size vs. asymmetry data. Therefore, it may provide high throughput and reliable screening and classification of bioaerosols using scattering characteristics.
PL
Rozmiar i kształt cząstek biologicznych są ważnymi parametrami pozwalającymi na rozróżnianie pomiędzy różnymi rodzajami cząstek. Przeprowadzone zostały badania aerozoli pochodzenia biologicznego takich jak pyłki roślin, przetrwalniki oraz wegetatywne bakterie. Substancje te wykazywały różne właściwości morfologiczne. W wyniku przeprowadzonych badań przy pomocy optycznego analizatora wielkości i kształtu cząstek znaleziona została wysoka korelacja pomiędzy właściwościami rozpraszania światła a rzeczywistymi właściwościami cząstek określonymi na podstawie SEM (Skaningowego Mikroskopu Elektronowego) oraz mikroskopu fluorescencyjnego. Przedstawione badania pokazują, że HCA (Hierarchical Cluster Analysis) umożliwia szybką, wiarygodną, prowadzoną w sposób ciągły analizę i klasyfikację bioaerozoli w oparciu o ich charakterystyki rozproszeniowe.
EN
This paper presents calculation of the electron-impurity scattering coefficient of Bloch waves for one dimensional Dirac comb potential. The impurity is also modeled as delta function pseudopotential that allows explicit solution of the Schrodinger equation and scattering problem for Bloch waves.
EN
We investigate the dependence of the [formula] dispersive estimates for one-dimensional radial Schrödinger operators on boundary conditions at 0. In contrast to the case of additive perturbations, we show that the change of a boundary condition at zero results in the change of the dispersive decay estimates if the angular momentum is positive, l ∈ (0,1/2). However, for nonpositive angular momenta, l ∈ (—1/2,0], the standard [formula] decay remains true for all self-adjoint realizations.
EN
In the present investigation, artificial neural networks are applied to model scattering and absorption properties occurring in particle radiation interaction for numerical simulation of pulverized coal combustion. To determine averaged scattering and absorption properties, an averaging procedure over spectral incident radiation profile and particle size distribution is applied. These averaged properties then are approximated by means of an artificial neural network. A study to determine a suitable network architecture is performed.
EN
We describe a new method to separate ballistic from the scattered photons for optical tissue characterization. It is based on the hypothesis that the scattered photons acquire a phase delay. The photons passing through the sample without scattering or absorption preserve their coherence so they may participate in interference. We implement a Mach-Zehnder experimental setup where the ballistic photons pass through the sample with the delay caused uniquely by the sample indices of refraction. We incorporate a movable mirror on the piezoelectric actuator in the sample arm to detect the amplitude of the modulation term. We present the theory that predicts the path-integrated (or total) concentration of the scattering and absorption centres. The proposed technique may characterize samples with transmission attenuation of ballistic photons by a factor of 10-14.
EN
Concept of fibre spontaneous Raman scattering utilizing for distributed temperature sensing is presented. Chosen approach uses both backscattered Stokes as reference and anti-Stokes as detection signals. The analysis is carried out towards Stokes and anti-Stokes bands temperature dependence. In order to achieve best measurement accuracy influence of maximum modulation frequency on spatial resolution is verified. Analysed technique allows to calculate temperature along the fibre with 5 m space precision and 1°C temperature precision. Simulations involve 200 m standard single mode fibre in temperatures in range < -5°C , 60°C> with 2x1100 m reference fibre maintained in 22°C.
PL
Koncepcja wykorzystania rozpraszania Ramana we włóknie światłowodowym do rozproszonego pomiaru temperatury została przedstawiona. W wykorzystanym podejściu użyto zarówno światła rozpraszania Stokes’a i anty-Stokes’a odpowiednio jako sygnałów odniesienia i czujnikowego. Analiza opiera się na fakcie zależności rozpraszania w pasmach Stokes’a i anty-Stokes’a od temperatury. W celu optymalizacji jakości pomiaru oceniono wpływ maksymalnej częstotliwości modulacji lasera na przestrzenną rozdzielczość pomiaru. W analizowanym przypadku oraz przy przyjętych wartościach parametrów możliwa jest realizacji pomiaru z dokładnością przestrzenną na poziomie 5 m i temperaturową 1 °C. W symulacjach badany jest odcinek 200 m światłowodu czujnikowego G.652 w temperaturach z zakresu < -5°C , 60°C> oraz dwóch odcinków światłowodu odniesienia od długości 1100 m w temperaturze pokojowej 22°C.
EN
The present paper discusses the mechanism of the wind-induced scattering of permeable unit flooring decks loosely laid on the rooftops and balconies of high-rise buildings. Firstly, the scattering mechanism of decks was investigated, based on a blowing test using a blower and actual decks. Subsequently, a simulation model was constructed for estimating the internal pressures under the decks (pressures acting on the bottom surface of decks) obtained from a wind tunnel experiment – this is based upon the unsteady Bernoulli equation and the time history of external pressures on the rooftop and balconies. Combining the simulated internal pressures and the experimentally obtained external pressures, the time history of net wind pressures acting on the decks were computed. Finally, the threshold wind speed of scattering (scattering wind speed) was obtained by applying the scattering mechanism to the simulated time history of the net wind pressures.
PL
W niniejszej pracy omówiono mechanizm rozwiewania przez wiatr przepuszczalnych podestów tarasowych luźno ułożonych na dachach i balkonach wieżowców. W pierwszym etapie przeanalizowano mechanizm rozwiewania podestów przy użyciu dmuchawy i rzeczywistych podestów. Następnie zbudowano model symulacyjny do szacowania ciśnienia wewnętrznego na podesty (ciśnienie działające na dolną powierzchnię podestów). Model oparto na nieustalonym równaniu Bernoulliego czasowych ciśnienia zewnętrznego działającego na dach i balkony, które zostały otrzymane w ramach eksperymentu przeprowadzonego w tunelu aerodynamicznym. Na podstawie symulowanych ciśnień wewnętrznych i uzyskanych doświadczalnie ciśnień zewnętrznych, obliczono przebieg czasowy całkowitych ciśnień działających na podesty. W ostatnim etapie obliczono progową prędkość wiatru podczas rozwiewania (prędkość rozwiewania) przez zastosowanie mechanizmu rozwiewania do symulowanych przebiegów czasowych ciśnienia wiatru.
PL
W artykule opisano metodykę pomiaru parametrów chropowatości powierzchni za pomocą zbudowanego w IOE WAT zautomatyzowanego skaterometru kątowego. Zaprezentowano wyniki pomiarowe dla trzech wybranych polerowanych powierzchni: z krzemu, z germanu oraz ze stali nierdzewnej. Przedstawiono badania porównawcze wykonane za pomocą scatteroscope SCAT-4. Oszacowano powtarzalność pomiaru i zakres pomiarowy dla skaterometru kątowego.
EN
The experimental procedure for measurements of smooth surface roughness parameters using automated angle scatterometer, built at the Institute of Optoelectronics (IOE), is described. The results of measurements and their analysis for three chosen polished surfaces: silicon, germanium, and stainless steel are presented. The comparative investigations using scatteroscope SCAT-4 are performed. The repeatability and measurement range for built at IOEangle scatterometer is estimated.
PL
W artykule opisano podstawowe parametry chropowatości powierzchni. Przedstawiono metodę obliczenia tych parametrów dla powierzchni gładkich na podstawie pomiaru funkcji BSDF charakteryzującej rozproszenie z badanej powierzchni. Opisano zbudowany w IOE WAT zautomatyzowany skaterometr kątowy służący do pomiaru powyższych parametrów.
EN
The basic parameters of surface roughness are described in this article. The method of calculation of these parameters from measurement of BSDF function characterizing scatter from surface is shown. Automated angle scatterometer, built at the Institute of Optoelectronics of the Military University of Technology (IOE MUT), used for measurements of above parameters is described.
EN
We analyze the effects of coloring of a beam traversing a light-scattering medium. Spectral investigation of the effects of coloring has been carried out using a solution of liquid crystal in a polymer matrix (polymer-dispersed liquid crystals – PDLC). It is shown that the result of coloring of the beam at the output of the medium depends on the magnitudes of the phase delays of the singly forward scattered partial signals. We consider the influence of interference coloring effect on the transmission scattering and spatial-frequency filtering of the radiation which has passed through the PDLC.
EN
The Rayleigh–Gans (R–G) approximation is widely employed in various optical models to simulate the optical response of transparent media. However, the R–G concept can only succeed if the refractive index of scatterers approaches that of surrounding medium. In addition, the sizes of scattering domains are assumed to be small enough. Because of these reasons, the validity of R–G solution is fairly limited. In this paper, a semi-analytical extension to the R–G theory is introduced, resulting in an approximate formula for efficiency factor for scattering Qsca. It is proven numerically that this formula works much better than that for traditional R–G model. The computations have been made on absorbing particles with sizes comparable to or smaller than the wavelength of an incident radiation. The conventional R–G theory is either inapplicable or at least inappropriate for such particles.
EN
The energy-critical, focusing nonlinear Schrödinger equation in the nonradial case reads as follows: [formula]. Under a suitable assumption on the maximal strong solution, using a compactness argument and a virial identity, we establish the global well-posedness and scattering in the nonradial case, which gives a positive answer to one open problem proposed by Kenig and Merle [Invent. Math. 166 (2006), 645-675].
17
Content available remote Revisiting the role of oceanic phase function in remote sensing reflectance
EN
The effect of angular structure differences between measured and best-fit analytical phase functions of the equivalent backscattering ratio on calculated reflectance values was studied and shown to be significant. We used a Monte Carlo radiative transfer code to check the effect of choosing different analytical (several Fournier-Forand (1994) and Henyey-Greenstein (1941)) phase functions with backscattering ratios identical to the "classical" average Petzold function. We show that the additional variability of the resulting water leaving radiance is about 7% (4% between the Fournier-Forand functions themselves) for most scenarios. We also show a previously unknown maximum of the discrepancy (up to 10%) for highly scattering waters. We discuss the importance of relative differences in phase function for different angular ranges to this maximum and to the behaviour of the discrepancy as a function of solar zenith angle.
EN
The paper focuses on the problem of test signal selection in determining the sound scattering coefficient in accordance with ISO 17497-1. Research shows that the use of MLS signal is preferred in this procedure. The sine sweep signal, despite its advantages, presents certain limitations if the sample is moving during measurement. An attempt has been made to develop a method that allows for minimization of error, demonstrating the dependence of the obtained values of the sound scattering coefficient on the rotational speed of the turntable and type of test signal. Conditions for the application of the sine sweep signals in continuous and discrete measurements were defined.
19
Content available Sound Diffusers with Fabric Covering
EN
Fabric covering is often used by designers, as it can easily mask acoustic structures that do not match an interior. However, in the case of sound diffusers based on change in the phase of the reflected wave, the use of fabric covering is not without its effect on acoustics. It reduces the effectiveness of these structures and raises acoustic absorption. In the paper, the authors analyzed the acoustical properties of a selected fabric used to cover sound diffusers. Sound absorption and scattering coefficients for a system composed of sound diffusers and a fabric situated at different distances d were measured. The results were compared to the sound absorption predicted on the basis of Kuttruff’s and Mechel’s theoretical models. Analysis of the results indicates that the fabric has a significant influence on the system’s acoustic parameters. It is also observed, that fabric applied directly on a phase grating diffuser, produces higher absorption than when it is at some distance from it.
EN
The paper deals with the problem of acoustic correction in historic opera theatres with the auditorium layout in the form of a horseshoe with deep underbalcony cavities limited with a semicircular wall surface. Both geometry of the cavities and excessive sound absorption determine acoustic phenomena registered in this area of the hall. The problem has been observed in the Theatre of Opera and Ballet in Lviv, Ukraine, where acoustic tests were carried out, simulation calculations performed, and finally a diffusion panel worked out designed for the rear wall of the underbalcony space. Acoustic measurements carried out after installation of the diffusers revealed favourable changes in the sound strength factor G within the range of medium and high frequencies in the underbalcony and auditorium centre area. By replacing textile tapestry with diffusion panels, a significant reduction of sound absorption was achieved for the frequency range above 1 kHz and an increase of uniformity of acoustic parameters registered in the hall. The method presented in the paper can be applied in historic halls of the similar type as well as contemporary rooms where there is a need for correction of acoustic flaws related to sound focusing or the echo effect.
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