Transparency Coefficients Research Articles

Sandiaoling eco-friendly tunnel soundscape and virtual reality analysis

Soundscape of Sandiaoling Ecological Tunnel, a 1.852 km bike path tunnel, has been studied for the taxonomy of sound sources, equivalent sound pressure levels, and the perceived sonic quality. This paper focuses on examining simulated sound source propagations in the tunnel using both omni and directional sound sources with Odeon Room Acoustic software. Additionally, it compares the specific receivers’ auralizations with in situ recorded sounds in a virtual reality model along with a questionnaire to evaluate the distinctions between the two. The preliminary results showed that the simulated sonic quality in tunnel is less reverberant than expected. Proximity of receivers to sound source, the boundary of air to source and receivers inside tunnel as well as the absorption, scattering and transparency coefficients of materials used in simulated model are adjusted. Future work will explore into audio post-production and visual effects.

Estimating the influence of various factors on the uncertainty of light collection simulation in scintillators

The paper is dedicated to the evaluation of statistical uncertainty of simulating the process of light transfer in NaI (Tl) and BGO scintillators by Monte Carlo method. The DETECT2000 program with a unified surface model was used. The process of light transfer (“fate”) by light photons was traced from the moment of appearance in the scintillator to the moment of passing through its exit window. The light collection coefficient was determined as the ratio of the number of photons that passed through the exit window to a given number of emitted photons. Different values of the number of emitted photons, optical transparency coefficients and fractions of the surface diffuse reflection were set. Multiple repetitions of the simulation process for a different set of properties made it possible to evaluate the precision and type A uncertainty of simulating the light collection coefficient for all possible options. It is shown that the uncertainty decreases when the statistics of the emitted photons is increased, and increases when the transparency and diffuse reflection fraction are decreased.

Modification of active region of resonant tunnel diode

Interest in the study of mesoscopic structures has grown significantly in recent years. This is primarily due to the development of semiconductor technology, which makes it possible to create structures with sizes of the order of units and tens of nanometers. The linear dimensions of such structures are inferior to the de Broglie wavelength of electrons, so the transport of electrons is determined mainly by their wave properties, which, in turn, leads to a number of new effects.
 Mesoscopic structures include the resonant tunnel diode (RTD), first proposed by Esaki and Tsu, and which is one of the first nanoelectronic devices. It consists of a semiconductor layer with a fairly narrow band gap, a quantum well (QW) layer located between two semiconductor layers (barriers) with a wider band gap. These layers, in turn, are located between the layers (spacers) of weakly doped narrow semiconductor, followed by highly doped layers of the emitter and collector. There are one or more energy levels of dimensional quantization in the QW. Under the action of bias voltage, the current passes through the RTD only if the emitter contains electrons that can tunnel. Resonant tunneling occurs at the energy level in the QW, and from there to the collector, where the spectrum of energy states is band. RTD has a very high speed of action, for example, it is known that the nonlinear properties of RTD persist up to 104 THz. The RTD is also of great power: it is the only device of nanoelectronics that can be used at room temperatures, and on the VAC of the RTD the areas of negative differential conductivity (NDC) are observed.
 In this article, the principle of a resonant tunneling diode is revealed, and the phenomena of tunneling in nanophysics are examined in detail. The volt-ampere characteristic (VAC) model of a two-barrier resonance tunnel diode is calculated. The paper investigates how the change of transparency coefficients and the reflection of the potential barrier of a rectangular shape affect the VAC of the RTD. This study can be the basis for further consideration of how the modification of the active region of the resonant tunnel diode affects its characteristics. In addition, the results of the research allow us to estimate qualitatively the energy required by electrons for tunneling through the structure of the RTD.

Subbarrier and Overbarrier Electron Transfer through Multilayer Semiconductor Structures

The transparency coefficients of a semiconductor structure consisting of alternating asymmetric potential barriers and wells, where the Bastard condition is taken into account, are calculated. It is shown that in the structure, an oscillation of the transmission coefficient of electrons depending on their energy is observed, which is caused by the interference of the de Broglie waves coming to the barrier and reflected from the potential barrier. The electronic states of a multilayer semiconductor structure consisting of alternating potential wells and barriers are analyzed.

Sub-barrier and Above-barrier Electron Transport Through Multilayer Semiconductors

The transparency coefficients of the semiconductor structure consisting of alternating asymmetric potential barriers and wells are calculated, where taken into account the Bastard condition. It is shown that both in the above-barrier and over barrier passage of electrons, tunneling oscillations arise. The amplitude, in this case, is determined not only by the values of the wave vectors, but from the values of the effective masses of the current carriers. This oscillation does not disappear even in symmetric structures if they have a difference in the effective masses of current carriers located in two neighboring regions. In symmetrical structures, an oscillation of the coefficient of the above-barrier passage of a particle depending on its energy should be observed without taking into account the Bastard condition. Calculations show that for equal values of the width of the well and the potential barrier, as well as jumps in the potential of the barrier or well, the amplitude of the oscillations of the coefficient of over-barrier passage of particles is greater than the coefficient of passage above the well. In the case of an asymmetric structure, these considerations remain valed, but the physical nature of the parameters, for example, the number of oscillations, reflection and transmission coefficients, strongly depends on the ratio of the effective masses of electrons in neighboring layers and from the ratio of the height of the left and right potential barrier (regarding to the well). In an asymmetric (and in a symmetric, but with different effective masses of electrons in different layers) semiconductor structure, oscillation should be observed depending on the coefficient of transmission through the potential barrier on the energy of electron. This oscillation is caused by the interference of waves going to the barrier and reflected from the potential barrier. Such an interference phenomenon in the structure does not disappear even in a symmetric structure due to the difference in the effective masses of electrons located in different regions of the structure. The electronic states of a multilayer semiconductor structure consisting of alternating potential wells and barriers are analyzed.

Zinc oxide films obtained by sol-gel method from film-forming solutions

Thin ZnO films on silicon and quartz substrates were obtained from a film-enriched ethanolic solution based on Zn(NO3)2⋅6H2O and salicylic acid. The effect of salicylic acid on the processes occurring in the film-forming solution was studied by IR spectroscopy, proton-magnetic resonance, and viscometry methods. The formation of zinc salicylate nitrate in an ethanol solution is established, where salicylic acid exhibits a monodentate property in the carboxyl group. Thermal formation of zinc oxide was determined by thermal analysis and X-ray diffraction. The analysis of optical and electrophysical characteristics of ZnO films was carried out using spectroscopy, ellipsometry and also a block for measuring the electrophysical properties of thin-film materials. It was found that ZnO films were semiconductors of the electronic type, characterized by an optical band gap of 2.91–3.21eV, a surface resistance of 109–106 Q. and transparency coefficients in the visible spectral range of 0.80–0.96. It was shown that as the thickness of the ZnO films increased the resistance decreased.

Parameterizing unresolved obstacles with source terms in wave modeling: A real-world application

Parameterizing the dissipative effects of small, unresolved coastal features, is fundamental to improve the skills of wave models. The established technique to deal with this problem consists in reducing the amount of energy advected within the propagation scheme, and is currently available only for regular grids. To find a more general approach, Mentaschi et al., 2015b formulated a technique based on source terms, and validated it on synthetic case studies. This technique separates the parameterization of the unresolved features from the energy advection, and can therefore be applied to any numerical scheme and to any type of mesh. Here we developed an open-source library for the estimation of the transparency coefficients needed by this approach, from bathymetric data and for any type of mesh. The spectral wave model WAVEWATCH III was used to show that in a real-world domain, such as the Caribbean Sea, the proposed approach has skills comparable and sometimes better than the established propagation-based technique.

АНАЛІЗ ПАРАМЕТРІВ МОДЕЛІ ПРОХОДЖЕННЯ УЛЬТРАЗВУКОВИХ ХВИЛЬ ЧЕРЕЗ ЗАНУРЕНУ У РІДИНУ ПЛАСТИНУ

The physical-mathematical model of the fall of an ultrasonic wave falling on the surface of a plate immersed in a liquid has been considered. The parameters of the model are the angle of incidence of the ultrasonic wave, the reflection and transparency coefficients for the incident wave and the thickness of the plate.This model is a theoretical basis for the practical implementation of the immersion method for measuring the velocities of propagation of longitudinal and transverse waves in samples of different materials. According to the experimental results of the propagation velocities of the longitudinal and transverse waves, the Poisson’s ratio of the material is determined. The materials of a typical plate are polymers that have different Poisson ratio in sign and magnitude. If the angle of incidence does not exceed the corners of the total internal reflection on the boundary of the liquid – solid for the longitudinal and transverse waves propagation in the plate, then the reflection and transparency coefficients are the real numbers. In this case, the squares of the modules of these quantities are the reflection and transparency coefficients of the energy of the wave. For the incident ultrasonic wave, reflection and transparency coefficients are calculated, depending on the angle of the incidence, the thickness of the plate and the material of the plate The analysis of the obtained results shows that the functional dependences of the energy coefficients of reflection and transparency are clearly expressed maxima and minima at different angles and plate thickness. For this purpose, the conditions for full reflection for incident waves and transparency for a transverse wave at critical angles of incidence are analyzed. The critical angles of fall of an ultrasonic wave from a liquid are calculated, under which in a plate only a transverse wave propagates. Determined thickness of the plate for polymeric materials, in which there is a complete reflection and full passage of the incident wave.

Engineering of Eu dopant segregation in colquiriite-type fluoride single crystal scintillators

Colquiriite-type Eu-doped LiCaAlF6 and LiSrAlF6 (Eu:LiCAF and Eu:LiSAF) scintillator single crystals were grown using Al metal as a starting material to improve the Eu dopant segregation. All Eu:LiCAF and Eu:LiSAF single crystals using Al metal (Eu,AlM:LiCAF and Eu,AlM:LiSAF) indicated high transparency and effective segregation coefficients (keff) of Eu2%,AlM1%:LiCAF and Eu2%,AlM1%:LiSAF single crystals were significantly improved to the value of 0.40 and 0.99, respectively. EuF3 starting material reacted with Al metal before colquiriite-type phase was generated. As a result, Eu3+ ion in EuF3 was changed to Eu2+ ion which could be incorporated into Ca2+ and Sr2+ sites easily.

A series of dendronized hyperbranched polymers with dendritic chromophore moieties in the periphery: convenient synthesis and large nonlinear optical effects

Excellent optical transparency and NLO coefficients were achieved by introducing dendritic chromophore moieties to the periphery of dendronized hyperbranched polymers.

Parameterization of unresolved obstacles in wave modelling: A source term approach

In the present work we introduce two source terms for the parameterization of energy dissipation due to unresolved obstacles in spectral wave models. The proposed approach differs from the classical one based on spatial propagation schemes because it provides a local representation of phenomena such as unresolved wave energy dissipation. This source term-based approach presents the advantage of decoupling unresolved obstacles parameterization from the spatial propagation scheme, allowing not to reformulate, reimplement and revalidate the parameterization of unresolved obstacles for each propagation scheme. Furthermore it opens the way to parameterizations of other unresolved sheltering effects like rotation and redistribution of wave energy over frequencies. Proposed source terms estimate respectively local energy dissipation and shadow effect due to unresolved obstacles. Source terms validation through synthetic case studies has been carried out, showing their ability in reproducing wave dynamics comparable to those of high resolution models. The analysis of high resolution stationary wave simulations may help to better diagnose and study the effects of unresolved obstacles, providing estimations of transparency coefficients for each spectral component and allowing to understand and model unresolved effects of rotation and redistribution of wave energy over frequencies.

Thermal and optical properties of hyperbranched fluorinated polyimide/mesoporous SiO2 nanocomposites exhibiting high transparency and reduced thermo-optical coefficients

A series of hyper-branched polyimide (HBPI)/mesoporous SiO2 nanocomposite films were prepared from a fluorinated anhydride (6FDA), a fluorinated triamine (TFAPOB), and mesoporous SiO2 nanoparticles (NPs). The anhydride-terminated precursor of HBPI was functionalized using a coupling agent prior to mixing with SiO2 NPs. The morphologies and thermal-optical properties of the nanocomposite films were investigated, with particular focus on their optical transparency, refractive indices (n), and thermo-optical (TO) coefficients. The absolute values of TO coefficients (|dn/dT|) of HBPI film (50.8 ppm/K) were significantly reduced to 13.4 ppm/K by homogeneous dispersion of 15 wt% of SiO2 NPs. The HBPI/SiO2 composite films exhibited high thermal stability without significant weight loss of up to 400 °C in air. The films also exhibited small coefficients of linear thermal expansion (CTEs) within the range 30–40 ppm/K. In addition, enhanced interfacial interactions between SiO2 and HBPI significantly improve the optical transparency with cutoff wavelengths shorter than 450 nm. The refractive indices of HBPI/SiO2 composite films were found to range from 1.477 to 1.502, which agrees well with the calculated values. This study shows that the incorporation of SiO2 NPs in multi-functional HBPI matrix is a promising approach to prepare high performance thermally stable films for thermo-optic applications.

Effect of Cultivation Pattern on the Light Radiation of Group Canopy and Yield of Spring Soybean (Glycine Max L. Merrill)

Heilongjiang Province is the main soybean-producing area in china. In this study, we analyzed the canopy structure, dynamic characteristics of light radiation and yield of Hefeng50 (the main variety of soybean in Heilongjiang Province) under six different cultivation patterns (ORP, TPCR, ORCP, BRHD, SRHD and FPHD). The results showed that SRHD and BRHD at different growth period (blossom period R1, podding R3 and grain filing period R5) produced an even distribution of the population leaf area, suitable mean foliage inclination angle (MFIA), low transparency coefficients for defuse penetration (TCDP) and transparency coefficients for radiation penetration (TCRP), high leaf area index (LAI), extinction light coefficient (K value), fraction of radiation intercepted (FRI) and light energy utilization rate. Grain number, dry matter weight per plant, and yield of SRHD and BRHD were significantly higher than those of other cultivation patterns. The yield of SRHD, BRHD, ORCP, FPHD and TPCR was increased by 136%, 112%, 79%, 50.1% and 14.7%, respectively, compared to that of ORP. These results suggest that SRHD and BRHD are the optimal cultivation pattern for the improvement of soybean yield in phaeozem region of northeastern China.

POSS/TiO<sub>2</sub> Nanohybrids as Sun Protection Ingredients for Greenhouse Covers

Based on (3-methacryloxypropyl)-Polyhedral oligomeric silsesquioxane (MP-POSS) (MP), vinyl-POSS (VP), (3-glycidoxypropyl)-POSS (GP) and modified with 10, 20 and 30 wt-% titanium tetrabutoxide (TTB), three hybrid nanofilms (f-MPT, f-VPT and f-GPT) were prepared using hydrolytic condensation and crosslinking. The average transparency (AT) and absorption coefficients (AC) of the films were measured in the ranges of 280-2500 nm. The average transparency (AT) values of three films were about 10-11% (280-320 nm), 78-80% (320-400 nm) and 85-89% (750-2500 nm), which implies that these films indeed can provide a physical barrier for blocking the UV-B absorbed into greenhouse, indicating functionality of the POSS/TiO2 materials as the sun protection ingredients. The AT values of three films were in the order of f-MPT>f-GPT>f-VPT due to complete-cage structures of building blocks (POSS) and the size of organic branches covalently bonded to the silica network in the molecular structures. This indicates that VPT powder might be significantly better to selected for the sun protection factor (SPF). Lower mtransparency of the films containing 30 wt-% TTB fractions is ascribed to more amounts of TTB in the modified films.

Theoretical investigation of organic-inorganic hybrid crystal: Optical transparency and quadratic harmonic coefficients of 2-Amino-5-Nitropyridinium chloride

The IR and UV absorption cut-offs (λ$_{IR}$ and λ$_{UV})$ of an organic-inorganic hybrid nonlinear optical (NLO) crystal, 2-amino-5-nitropyridinium chloride (2A5NPCl), were investigated in the framework of density functional theory. The macroscopic quadratic NLO coefficients of the crystal were evaluated at the MP2/6-31+G** level coupled with the oriented-gas model. The calculated results reveal that the λ$_{IR}$ and λ$_{UV}$ are governed by the asymmetric N-H stretch of NH$_{2}$ group and the charge transfer (CT) transition from Cl$^{-}$ to 2A5NP$^{+}$, respectively. The optical transparency has been determined in the region 407-1415 nm. The analyses of the electronic absorption spectrum show that the CTs of both Cl$^{-}→$ 2A5NP$^{+}$ and π → p* within 2A5NP$^{+}$ moiety make dominant contributions to the β values. The studies of the oriented-gas model show that the crystal has large NLO coefficients.

Theoretical investigation of organic-inorganic hybrid crystal: Optical transparency and quadratic harmonic coefficients of 2-Amino-5-Nitropyridinium chloride

The IR and UV absorption cut-offs ($_{IR}$ and $_{UV})$ of an organic-inorganic hybrid nonlinear optical (NLO) crystal, 2-amino-5-nitropyridinium chloride (2A5NPCl), were investigated in the framew...

Electroceramics Research in India

Electroceramics research is driven by the technology development needs and the device applications in the fields of microelectronics, communications, automation, energy conservation, MEMS and others. Ferroelectric ceramics have been technically exploited because of their unique properties such as high dielectric permittivity, high piezoelectric & electromechanical coupling and discovery of electrical poling process. Under certain circumstances they show high optical transparency and electro-optic coefficients. High permittivity barium titanate based piezoelectric ceramics and their polymer composites show unusual properties for a wide range of applications in sonars, ultrasonic cleaners, micro-accelerometers, hydrophones, surface acoustic wave filters, delay lines, and microactuators etc. A number of organizations in India viz. academic institutions, research laboratories and industries are involved in the preparation, characterization and device fabrication of the electroceramic materials. This paper presents an overview of the ongoing work and the future prospects.

On the simulation of seat-dip effect using geometrical acoustics software

A group of Italian churches was surveyed in order to measure the most important acoustic parameters according to ISO 3382 Standard. Computer models of the same churches were made using acoustic simulation software. Absorption coefficients found in the literature were used and later calibrated to match predicted and measured T30 values. The results of the simulations were compared with the observed values, showing some discrepancies at mid-low frequencies. This discrepancy appeared to be due to a lack of direct sound in the measured responses, particularly at the 250-Hz and 500-Hz octave bands, indicating the probable presence of a seat-dip effect caused by the wooden pews. Since the acoustic simulation software provided the possibility to use acoustically semitransparent planes, this feature was used to simulate the effect of selective absorption of the direct sound due to the seat-dip effect. The comparison between measured acoustic parameters and those predicted including the simulation of the seat-dip effect showed that an improvement in the prediction accuracy can be achieved. Different configurations were tested in order to define the optimal placing of the semitransparent plane, and a criterion to choose the transparency coefficients is finally proposed.

On the instability of atmospheric optics in polluted areas

Abstract Clear-day-observations of direct and diffuse solar radiations at different wavelengths have been carried out in an industrial area, 30 km to the south of Cairo. Ratios of scattered and direct solar fluxes have been calculated as functions of air masses. The wavelength dependence of transparency coefficients of polluted air masses are also determined. The results obtained reveal obvious fluctuations of the atmospheric optics in the examined area. These results are of prime importance for some astrophysical problems and future projects of solar energy utilization.

Effects of algae on the Secchi transparency of the southeastern Mediterranean Sea

The mean transparency (37.5 m) measured by Secchi disk at “blue‐water” pelagic sampling stations in the southeastern Mediterranean Sea during 3 yr was greater than in most other seawater. Our measurements in the Mediterranean and those by others in the English Channel, Atlantic Ocean, and Pacific Ocean obey the Lambert‐Bouguer law if it is specified that transparency depends on the vertical attenuation coefficient for downward irradiance in the waveband of underwater sunlight that has lowest attenuance. Mean downward irradiance (±95% C.L.) at the depth where a Secchi disk disappears, calculated from 187 paired estimates of transparency and attenuation coefficients from these oceanic regions, is 22±1% of surface irradiance in this waveband. This value is significantly larger than the value (18%) that has been used widely since an early study by Poole and Atkins, who calculated attenuation coefficients incorrectly.As predicted by the Lambert‐Bouguer law, reciprocal transparency was proportional to the attenuation coefficient for the most‐penetrating waveband. Attenuance of this waveband and reciprocal transparency both increase linearly with increasing concentration of phytoplankton chlorophyll in pelagic water. Chlorophyll concentrations in pelagic Mediterranean water were very low (0.02–0.14 mg m−3), but attenuance by units of phytoplankton chlorophyll was about 10 times larger than in more productive seawater, probably because blue light was predominant and many of the phytoplankton were very small coccolithophorids (cell diameters <10 µm) with optically dispersive cell surfaces.Measurements of transparency by Secchi disk are as accurate and precise as estimates of attenuation coefficients calculated from irradiances measured at sea with photoelectric sensors. The Poole‐Atkins equation for transparency in terms of the waveband with lowest attenuance describes the variation of transparency as well as the Duntley‐Preisendorfer equation does. Much of the information needed for interpreting satellite ocean‐color imagery could be obtained very efficiently with closely spaced measurements of transparency from surface vessels during synoptic cruises.