Search

This paper presents acoustical properties of balsa core sandwich panels. The sandwich panel is composed of glass fiber, carbon fiber, and balsa wood. The acoustical properties of the panel is evaluated in terms of absorption coefficient. The impedance tube technique utilizing ASTM Two-Load method is used for the sound absorption and characteristics. Different samples of the sandwich panel are prepared by varying the thickness of core. The sound absorption characteristics is observed to be sensitive to the thickness of samples and direction of incidence of sound waves. Along with the core thickness effect, the effect of placing samples in the direction of sound incidence is also studied. The placement direction is also observed to have a strong influence on the sound absorption. The thinner core sandwich panel has higher sound absorption in case the sample faces the sound source from the carbon fiber side. Whereas thicker core sandwich panel has higher absorption in case of the sample facing the sound source from the glass fiber side. [ABSTRACT FROM AUTHOR]

Two dimensional (2D) van der waals (vdW) Janus heterostructures are the smart artificial materials with unique phys-ical, chemical, and quantum properties. Here, the electronic and optical properties of 2D Janus MoSeTe/WSeTe heterostructures are investigated systematically at different rotation angles by density functional theory. Four rotation angles were chosen in be-tween 0 - 600 by considering the fact that the lattice mismatch between the monolayers will be minimum. The relative rotation between the monolayers provide an extra degree of freedom to enable various fascinating phenomena in the heterostructure. The phonon dispersion and adhesion energy confirms the Janus monolayers and its heterostructures were found to be dynamically and thermodymically stable respectively. The bandgap of the heterostructure reduces as compared to its monolayer and lie in the range between 0.4 - 0.6 eV for all considered rotation angles. It is interesting to note that the MoSeTe/WSeTe heterostructure possess a type-II band alignment, which is a crusial parameter for separation of carriers. In addition to this, the heterostructure is opti-cally active in visible to infrared region with a high value of absorption coefficient for θ = 00. These results show the potential applications of 2D Janus heterostructures in nonoelectronics, spintronics, and optoelectronic devices. [ABSTRACT FROM AUTHOR]

This document discusses the thermal oxidation stability factor of mineral engine oils at high temperatures. The determination of the coefficient of thermal oxidative stability is also considered. Based on the experiments, graphs of the dependence of evaporability on the time and temperature of evaporation of the 1800 С mineral engine oil, as well as a graph of the dependence of the coefficient of thermal oxidative stability on the coefficient of absorption of light flux and the temperature of testing the 1800 С of the mineral engine oil were built. Based on the obtained values, conclusions were drawn. [ABSTRACT FROM AUTHOR]

Two renovation plasters with blended binder based are presented in this paper. The porosity of plaster was increased by the application of expanded perlite. This lightweight aggregate was used alone as well as in combination with ordinary silica sand. Binder of plaster composed also of two kinds, pure lime were supplied by ceramic powder. This pozzolanic material led to improvement of mechanical properties and therefore should compensate for their lowering caused by plaster lightening. Physical properties such as basic physical, mechanical and durability characteristics were determined, and the results are discussed in this paper. The plaster with lightweight aggregate reached desired high porosity and appropriate water transport characteristics to be applicable in the field of building renovation, while the combination of silica sand with lightweight aggregate showed the water absorption coefficient slightly lower than the requirements of the standard. [ABSTRACT FROM AUTHOR]

The frequency dependence of the light absorption coefficient due to the successive absorption of two and three quantum associated with direct optical passages between the valence and conduction bands in crystals with narrow band has been studied. A calculation was carried out based on the perturbation theory in the Kane approximation, where we assume that the energy spectrum of electrons is spherically symmetric. A quantitative analysis of the frequency dependence of the three-photon absorption coefficients of radiation in semiconductors with narrow band has been carried out. [ABSTRACT FROM AUTHOR]

Industrial wastes are often contaminated with heavy metals and thus constitute a danger to the environment. One of the safe ways to treat such contaminated wastes is to immobilize heavy metals by using various binders. Suitable binders may include magnesium potassium phosphate cement (MKPC), which is also referred to as a low-carbon material. This study evaluates the ability of the MKPC matrix to simultaneously immobilize three heavy metals, namely Ba, Pb and Zn ions. The heavy metals were applied to the mixing water in the form of soluble salts at a concentration of 2.5% of the heavy metal by weight of the binder. The basic structural and mechanical properties of the hardened specimens were determined and an evaluation of the parameters for the transport of liquid water was carried out. It was found that the presence of metals had a negative effect on the mechanical properties. However, the MKPC exhibited an excellent low water absorption coefficient, and the addition of heavy metals further reduced this parameter by up to 60%, promoting overall immobilization. This makes MKPC a very interesting material for immobilizing heavy metals in artificially contaminated materials, which could then be used in a variety of construction applications. [ABSTRACT FROM AUTHOR]

In this work, iron sulfide thin films were prepared by simple and low-cost chemical spray-pyrolysis method (CSP) using tilt deposition with a spraying angle of 45° and substrates temperature (200°C, 350°C). The precursors were iron nitrate (Fe (NO3)3.9H2O) and thiourea. The study shows the feasibility of using iron sulfide as a counter electrode in Dye-sensitized solar cells. It was found that the iron sulfide thin films with an amorphous structure gave the highest absorption coefficient (1.8×105cm−1) and highest conversion efficiency (1.8%) in DSSCs. This work also investigates the optimum conditions of substrate temperature, annealing temperatures, and the presence of sulfur powder and argon gas to obtain polycrystalline pyrite thin films with optimum energy gap and high absorption coefficient. [ABSTRACT FROM AUTHOR]

Duct liner is utilized as a thermal insulation to avoid thermal loss from the cooled-conditioned airstream and as a sound insulation in air-conditioning systems. Usually, fiberglass is used as duct liners. However, its hazardous splints are carried together with the airstream into space and they are inhaled by occupants. They may affect human health, whereby they cause respiratory problems and even cancer, if it is inhaled for a long duration. Apart from fiberglass, closed-cell polyurethane (PU) and polyethylene (PE) are also utilized as duct liners, however, they are undoubtedly expensive and harmful out-gassing may occur after a certain period. Hence, another cheaper and safer duct liner alternative is developed by using natural fiber. A natural fiber composite made from palm oil waste, specifically empty fruit bunch (EFB), which is abundant, was used as the main material and a low melt bicomponent (bico) fiber, which was made of polyethylene (PE) and polypropylene (PP), was selected as a binder. Apart from that, the EFB-Bico fiber composite is also safer to humans than fiberglass as it uses natural fibers. Three samples A, B and C of the EFB fiber composite, which is 300mm x 300mm x 20mm in size, were prepared via hammer milling, electronic sieving, blending, press-forming and baking process, before its thermal and acoustic resistivity are tested. The density of the samples was set low at 150 kg/m3. Sample A contained 90 wt% of EFB and 10 wt% of bico, while sample B had 80 wt% and 20 wt% bico and sample C encompassed 60 wt% of EFB and 40 wt% of bico. The thermal resistivity or heat flow resistance of the three samples A, B and C were calculated after the value of their thermal conductivity were found via thermal conductivity test according to ASTM E1530. Meanwhile, the acoustic test was conducted with aid of an impedance tube kit (50 Hz – 6.4 kHz) type 4206 in accordance to ISO 10534–2 and ASTM E-1050-12. Among all samples, sample C showed the highest thermal resistivity, R-value and acoustic absorption coefficient, which was 0.341 W/m2°K due to the highest amount of PP/PE fiber and 1.0 sound absorption coefficient for higher frequency between 2200Hz and 3400Hz respectively. The R-value of sample C was however 46% lower than the thermal resistivity of fiberglass, which had R-value of 0.635 W/m2°K, even though its sound absorption coefficient was close to that of fiberglass. Therefore, it was found that the thickness of the samples need to be doubled from 0.02m to 0.04m to achieve the same R-value as fiberglass. [ABSTRACT FROM AUTHOR]

Here in this presented work structural, electronic and optical properties of Janus MInS2 have been studied by using first principle calculation. The optimization is done by applying vacuum in z direction. MInS2 has the hexagonal structure. MInS2 has shown the semiconductor behavior. InS, AlInS2 has indirect bandgaps where BInS2 has direct bandgap. The MInS2 is dynamically stable. Total density of state (TDOS) and projected density of state (PDOS) are also calculated for MInS2. From real, imaginary part of the dielectric function optical absorption coefficient is calculated has shown absorption in UV region. Both AlInS2 and BInS2 has shown enhancement in absorption of light. and which shows the potential application in optoelectronic devices and its applications. [ABSTRACT FROM AUTHOR]

Using density functional theory, the effect of layer number and stacking pattern on the electronic and optical properties of PdSe2 is explored. The size of the band gap and optical properties are very sensitive to the stacking pattern. The monolayer PdSe2 (m-PdSe2) has band gap of about 1.29 eV and its value drops with rise in layer thickness. The band gap of bilayer PdSe2 (b-PdSe2) changes from 1.13 eV to 0.79 eV with stacking pattern AA and AB, respectively. The optical properties like dielectric function, absorption coefficient etc. are also calculated. The bilayer PdSe2 with stacking AB is found to have the most prominent optical properties. A red shift in optical properties is also observed as the number of layers increases. [ABSTRACT FROM AUTHOR]

This paper deals with the measured values of the acoustic absorbing coefficient related to some materials employed into complex casing structures under architectural and geometrical perspective. The analyzed materials are composed of PVC sheets or of sound absorbing melamine tested inside an impedance tube modified for this purpose. The materials are suspended such that the acoustic absorption is due only to the vibration of the material subject to the incident soundwave. This process has been executed by substituting the rigid and smooth end cap of the tube with another anechoic that simulates the behavior of the air at the back of the suspended material. The outcomes of the measurements have been reported in the frequency bands comprised between 200 Hz and 2 kHz. On this basis, the results can be utilized as input data of the software employed for the acoustic simulations of the room volumes that are intended to be designed. [ABSTRACT FROM AUTHOR]

In this work, we investigated the optical properties of natural dye extracted from the portulaca grandiflora flower. The eco-friendly solvent was used through the extraction dye process. The FTIR analysis was conducted to get functional group profile for the natural dye. The Ultraviolet-Visible spectroscopy was performed on the dye thin-film including the absorption spectra, absorption coefficient, refractive index, extinction coefficient, as well as the optical bandgap. The UV-Vis range showed a broad absorption band, including significant bandgaps. The pigment under investigation has narrow indirect bandgap of 1.54 eV and an Urbach energy of 5.33 meV. [ABSTRACT FROM AUTHOR]

The properties of PVA and starch polymer mixes doped with Rhodamine-B are the subject of this study., which has a weight-to-weight ratio of 1:1. PVA and starch polymer mixes with varying glycerin ratios of 0, 25, 30, 35, and 40% wt. Different percentages of the polymer mixture consisting of sarch/PVA with 30% wt/wt of glycerine) were doped with rhodamine dye (0,1,2,3,5). Samples were then analyzed using FTIR, which revealed active groups as well as a clear association between the materials used, Optical spectrum was also measured for the (300-900 nm) range, Optical characteristics of the combination, such as absorbance, absorption coefficient(α), optical energy gap(Eg) and Extinction Coefficient(K), have been researched. [ABSTRACT FROM AUTHOR]

In this work we extend our previous work on that type material and already reported. The photoelectric behavior of perovskite CH3NH3PbI3-x doped with Clx layers developed on TiO2:FTO using the spin-coating method. Perovskite parameters of the unit cell are calculated by XRD. The developed layer's morphology is shown the irregularity and porosity. In this work the to discover the behavior of developed perovskite layer on TiO2:FTO and spectral analysis of this. Therefore, the analytic studies of this substance are having a bandgap∼1.60 eV and this is shown the order of perfect absorption coefficient and bandgap in the range of 400 nm thin layers. This thin layer help to develop solar material and its devices make highly efficient solar panel. [ABSTRACT FROM AUTHOR]

To reach the European climate-neutrality by 2050, the strategic importance of a large energy-efficient renovation of the existing building stock is clear. Among the several retrofit solutions that can be adopted to reduce the impact of existing buildings, the addition of thermal insulation to external walls is often considered. From the building physics point of view, external thermal insulation is considered to be safer than interior one since it entails reduced risks of condensation. Nonetheless, unforeseen moisture accumulation may occur after the intervention, when dealing with traditional porous walls. To avoid moisture-related problems, correct insulation solutions must be chosen, accounting for moisture dynamics in the envelope. This study takes into analysis the massive walls of a traditionally constructed building located in the temperate climate of Lisbon. The hygrothermal behaviour of the walls, in their original and retrofitted configurations, is evaluated by means of mono-dimensional dynamic simulations. The thermal insulation solutions considered are three thermal rendering systems that are commercially available in Portugal, and they were characterized through experimental tests. For the sake of comparison, two more common insulation materials were also considered. Results show the importance of the parameters Aw (capillary water absorption coefficient) and sd (air-equivalent thickness) of the materials adopted in the retrofit. Furthermore, this study shows that for traditional porous walls the retrofitted configurations should be simulated not only under operational conditions, but also considering the drying from a very high-water content. If the latter scenario is not accounted for, moisture accumulation may be overlooked. [ABSTRACT FROM AUTHOR]

The dependence of moisture diffusion coefficients on moisture content can be modeled using pore size distribution curves. This seems to be a very convenient approach, because the curves can be readily measured by standard experimental techniques. On the other hand, the Boltzmann-Matano approach requires time consuming measurements of the moisture profile to determine the moisture diffusivity. Using two samples of a ceramic brick, in this paper we demonstrate that there are two serious limitations in the former approach that employs pore size distribution curves. Namely, an independent determination of a single value of the diffusivity and inadequate (oscillating) behavior of the diffusivity at low and high moisture contents. We address both limitations as follows. First, a single value of the diffusivity may be determined from water absorption coefficient. However, this value corresponds to a moisture content quite close to the saturation point where the result may be rather questionable. Second, by using pore size distributions curves with cut-offs at small and large pores, the behavior of the moisture diffusivity becomes plausible, without any oscillations. This indicates that parts of pore curves at small and large pores may require more careful treatment in the experimental determination and/or corrections in theoretical models. [ABSTRACT FROM AUTHOR]

In recent years, thin-film solar cells (TFSCs) such as the third generation based on earth-abundant elements have received more and more attention due to their high efficiency, low cost-effective, adjustable bandgap, non-toxicity, environmentally friendly, high absorption coefficient (>104 cm−1) and its p-type conductivity. In this study, the SCAPS-1D (Solar Cell capacitance Simulator one dimension) simulator was used to investigate the performance of four solar cells heterojunctions CuSbS2/CdS, Sb2S3/CdS, CZGSe/CdS, and CZTSSe/CdS. We have studied the effect of the thickness and the hole concentration of the absorber layer on the device performance. Furthermore, J-V characteristics and quantum efficiency are also studied to compare the performance of CZTSSe, Sb2S3, CuSbS2 and CZGSe solar cells. We found that the device with Sb2S3 is the best with the higher efficiency of 27,15%. [ABSTRACT FROM AUTHOR]

The phenomenon of reverberation has a significant impact on the acoustics of the interior of a given object. When designing interiors, reverberation time cannot be measured, and therefore computer simulations or theoretical models are used. In the article, the analysis was carried out in a dedicated computer program ODEON. Six rooms with a different shape of the ceiling covered with a membrane were simulated in the program. On this basis, the impact of the shape of the ceiling covered with the membrane on the acoustic properties of the room was determined. The obtained results demonstrate that the shape of the ceiling covered with a material having very high sound absorption coefficient in the room (3) affects the reverberation time. The shorter the reverberation time in the rooms (2) and (3) and the closer the sound sources P1 and P2, the higher are the values of the STI index. [ABSTRACT FROM AUTHOR]

In this paper, the effect of quantum confinement on the energy band structure and the absorption coefficient of the spherical quantum dot has been investigated. The quantum dot chosen from the zinc blende materials such as ZnS, ZnSe and ZnTe. The approximation of the effective mass and the degenerate valence energy band at the center of the first Brillion region are considered in our calculations. Our theoretical calculations included dispersion relation of the bulk and the effect of quantum confinement on the energy band gap, joint density of states and absorption coefficient of quantum dot. We will display the curves of ZnS only, because the curves of other zinc blende materials are in the same behavior. All results show a good agreement between our theoretical calculations and experimental evidence from the literature. [ABSTRACT FROM AUTHOR]

Lower hybrid power absorption analysis is presented on the EAST high-density plasmas using the power modulation technique. The change in the plasma and magnetic energy is monitored to evaluate the power absorption coefficient by linearizing the change for the first 10 msec for the given input power. The power absorption coefficient evaluated is approximately 0.44 (0.35) for 4.6 GHz (2.45 GHz) at n̄e = 3.5x1019 m-3 GENRAY/CQL3D current drive modeling suggests a combination of antenna spectrum, accessibility, and edge losses could primarily be responsible for the observed level of power absorption. Evidence of first-pass parasite LH power flow causing impurity sputtering is also reported, suggesting a need for optimum power coupling. Implications of the experimental findings are discussed. [ABSTRACT FROM AUTHOR]

The Organic dyes are appealing optical substances in many applications in bio photonic and photonic. The present research includes study Non-linear optical peculiarities of Rhodamine 6G in disaccorded concentrations (0.03m M, 0.05 m M,0.1mM),a The nonlinear calculated included using (Z-Scan) technique. The measurements were achieved with using (CW) lasers at wavelengths (405nm, 473 nm, 532nm, 650nm) and with laser power of (1.49 mw, 4.35mw, 11, 56 mw, 5mw) respectively. The results showed that Nonlinear refraction index coefficient and nonlinear absorption coefficients increased with increasing the concentration of samples, the nonlinear refractive index n2 of Rhodamine 6G dye dissolved in Ethanol were detect that based upon the wave length of laser with concentration of sample. [ABSTRACT FROM AUTHOR]

HgSnP2 is mechanically and thermodynamically stable due to its highest absorption coefficient. In this work, we performed first principle calculation such as structural, optoelectronic properties of HgSnP2 within density functional theory (DFT) using WIEN2k code. Structural and electronic properties were obtained through modified Becke-Johnson (mBJ) potential. We reported band gap for HgSnP2 is 0.54 eV from density functional calculation, which shows its usefulness in the lower layer of multi-junction solar cells. We plotted absorption spectra which gives the high IAC value 201.48 (×104 eV/cm) and exhibit lower reflection value of HgSnP2 also reveals partial isotropic nature of compound. [ABSTRACT FROM AUTHOR]

This investigation depicts an elaborated analysis of optical, structural and electronic properties based on the first-principles method. It is carried out on WIEN2k-a density functional theory tool. BaCu2S2 compound is utilized for the optoelectronic investigation. We used the optimized parameters to yield our results using the Perdew Burke Ernzerhoff exchange-correlation functional. The bandgap obtained is 1.09 eV using modified Becke-Johnson potential. The electronic structure is explained through DOS and bandstructure plot. The dielectric tensor, absorption coefficient, reflection along with refraction value calculation frames the optical property analysing the details of the system. [ABSTRACT FROM AUTHOR]

In this paper, we determined the structural and optoelectronic properties of BeSiN2 chalcopyrite to explore its role in a photovoltaic material. The structural, optical and electronic properties of BeSiN2 are determined by using DFT approach which is based on the Wien2k code. The first principle method has been executed by considering Tran-Blaha modified Becke Johnson potential approximation (TB-mBJ). The BeSiN2 electronic properties are determined by analysing its band structure and density of states. Our results predict that the BeSiN2 exhibits direct band gap nature with 3.583 eV value. The optical properties of BeSiN2 are explained through some parameters like dielectric function, absorption coefficient, reflectivity and refraction. [ABSTRACT FROM AUTHOR]

In general, noise is a problem and it can be found everywhere, including at the aero activity such as aircraft maintenance vicinity. The object of the noise case selected in this study is the Auxiliary Power Unit (APU) which is the part of Airbus A330 aircraft with the APU type GTCP 331-350. The noise of APU while operate during maintenance can affect the occupational health and safety conditions of the worker. In this study, a micro-perforated panel (MPP) is used to absorb or reduce the sound intensity. MPP is made of a thin flat material where in this research using acrylic and placing small holes on its surface. Both experimental and numerical method are used in this research. The first step in performing the MPP design is numerically to obtain the geometry according to the absorption coefficient target at the specified noise frequency. For the experimental or testing phase of finished MPP design, a tool called an impedance tube is used. The test procedure refers to the ISO 10534-2 or ASTM E 1050-90 document. There are two types of impedance tube, first in diameter of 10 mm and the second one in 3 cm. The 10 mm impedance tube has the frequency range from low to medium frequency while the 3 mm for the high frequency testing. The absorption coefficient prediction value from numerically MPP design for the targeted frequency of 695 Hz gets 0.8819 versus the actual value after test in impedance tube is 0.8875. Furthermore, the highest absorption coefficient value for design or prediction and actual testing lies at the exact frequency of 750 Hz where for predictions has 0.95 and 1 for actual testing. Based on these results it can be concluded that MPP has the potency to reduce the APU noise. Henceforth it will be interesting to apply the MPP technology directly to the APU compartment on aircraft. [ABSTRACT FROM AUTHOR]

Technological development and population growth have led to increased noise. In an effort to manage noise level, sound level testing equipment and sound-absorbing materials are required. However, the availability of sound level testing equipment such as sound level meter (SLM) is still very limited. Additionally, commercial materials that have been developed as sound absorbers/diffusers can have negative impacts on the environment. Therefore, in this study, a simple and inexpensive sound level meter system using a sound sensor and composite board made from oil palm frond waste has been developed. The SLM calibration was performed using an Android-based sound level meter app, and the system performance was evaluated using a porous material in the form of a composite board. The assessment was conducted using two main schemes: (i) no intervening barrier between sound source and SLM; and (ii) sound source was covered with a box from the composite board. The test results showed good performance of the SLM system with the coefficient absorption 0.64. Further, this study also varied the size of the powder used in the production of the composite board. Based on the results obtained, the composite board with fine powder composition has better sound suppression capability. [ABSTRACT FROM AUTHOR]

The implementation of parameter optimization in a hybrid Micro-perforated panel (HMPP) aims to improve absorption performance as a perfect sound absorber. However, there is a valley in the absorption coefficient curve which reduces the average absorption coefficient value. This study implements optimization techniques to allow HMPP to be a perfect absorber and broadband sound absorber. For this reason, optimization uses three heuristic optimization methods that are widely applied in absorber systems, namely Genetic Algorithm (GA), Simulated Annealing (SA), and Cuckoo Search Algorithm (CSA). The results obtained will be discussed to compare the performance of each method in the case of HMPP to achieve the target of a broader and perfect absorption range. The fitness value is the maximum average value of the highest absorption coefficient over the optimization frequency range. The optimization result of HMPP at a frequency of 100-3000 Hz is 78.5% for SA, 81.6% for GA, and 88.5% for CSA. CSA produces the highest fitness value. Thus, CSA method optimization is the best in overall. [ABSTRACT FROM AUTHOR]

A subwavelength structure absorber is developed and demonstrated. It differs from other subwavelength systems, we use several coiled-up resonators combined in a stack way. Such a system is proposed to cover acceptable absorption coefficient as well as obtaining relatively wider absorption bandwidth. Moreover, it is expected that such a system offers a great tunability and configurable system in absorption to meet targeted frequency and bandwidth. In this article, experimental results are presented as an early investigation to prove the concept. [ABSTRACT FROM AUTHOR]

It has been known that sound absorptions of vegetation are poor, particularly at a low and medium frequency. In contrast, vegetation is widely used as part of a building or urban city design and development. It is instructive to seek technical ways to enhance sound absorption of vegetation. Thereby, the use of vegetation is more beneficial to noise reduction due to traffic noise. In this study, sonic crystal is introduced near the vegetation to enhance its absorption coefficient. The Finite Element Method (FEM) is employed to model the combined system of vegetation and sonic crystal. At the same time, the resulting calculation in terms of absorption, reflection, and transmission coefficients are discussed. The effect of variation in vegetation length, number of the sonic crystal lattices, and lattice length to the mentioned parameters are also investigated in this study. The result shows enhancement in both sound absorption and reflection of vegetation while the transmission decreased due to reabsorption of reflected sound from sonic crystal. Increasing the vegetation layer length leads to an overall increase in sound absorption, while increasing the number of sound sonic crystal layers leads to a higher gradient of change on absorption coefficient between the bandgap frequency and the non-bandgap frequency. Variation in lattice length leads to variation in the bandgap frequency, where enhancement of sound absorption occurs. Although further investigation is needed, the simulation result shows that the combination of vegetation and sonic crystal is favorable to reduce traffic noise significantly. [ABSTRACT FROM AUTHOR]

The non-linear optical characteristics of organic laser dyes (Acriflavine,Orcein, and Azur-B) dissolved in Ethanol solvent with concentration (10−5M) were investigated in this study. The UV-VIS spectrophotometer measures the spectra' linear optical characteristics. It was determined the nonlinear optical characteristics by using the Z-Scan method, which represents a very sensitive approach for obtaining two essential optical phenomena: nonlinear refractive index and nonlinear absorption coefficient, in two different situations (close aperture) and (open aperture). The results indicate (Acriflavine,Orcein, and Azur-B) is a promising material to be used in photonic and nonlinear optical devices.An optical power limiter uses this promising medium for a range of optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this paper, focus is placed on "lightweight and fine powders" which have small particle size and bulk density and exhibit unique sound absorption characteristics at low frequencies due to longitudinal vibration of powder particles. Theoretical analysis of the sound absorption coefficient of powder layers requires the peak frequency of sound absorption measured experimentally. In this study, we clarified the relationship between powder properties and sound absorption characteristics, and predicted the sound absorption coefficient of the powder layer from the experimental equation based on the accumulated data. This made it possible to classify powders in which sound absorption due to longitudinal vibration occurs based on the relationship between the "areal density per particle layer," which is indicated by "particle size multiplied by bulk density," and the peak sound absorption value. Moreover, from the plot of "areal density per particle layer" and "first-order sound absorption peak frequency from experiment," the experimental formula for the first-order sound absorption peak frequency was regressively obtained. By using the experimental equation obtained in this study, it was possible to show how to estimate the sound absorption coefficient from the properties of each powder alone. [ABSTRACT FROM AUTHOR]

The influence of ground absorption on calculations using the CRTN 1988[1] and CRN 1995[2] methodologies has been researched and is well understood. For previous rounds of strategic mapping, this has led to the recommendation of adopting CORINE Land Cover[3] data which can be used to allocate appropriate ground absorption coefficients to represent the acoustic absorptivity or reflectivity of the ground surfaces that the dataset describes. However, there has been no equivalent studies into how the selection of a ground cover dataset may influence calculated noise levels using the CNOSSOS-EU[4] methodology. Therefore, to support Round 4 of the strategic mapping, an investigation into the effect of ground cover selection on CNOSSOS-EU calculated levels and calculation times was undertaken. Test models were developed incorporating prepared ground cover datasets based on CORINE Land Cover 2018, CEH Land Cover Map 2019[5] and OS Mastermap Topography Layer[6], (a 'low', 'medium' and 'high' resolution dataset respectively) and used to perform noise calculations across a rural and urban/suburban propagation environment using the CNOSSOS-EU methodology. Comparison between the results of all models indicated that the medium resolution dataset offered the best compromise between introducing a low level of uncertainty in the calculated noise levels and improved calculation time for national coverage noise mapping. [ABSTRACT FROM AUTHOR]

In the field of room acoustics, it is important to determine the absorption coefficients of the wall surface, which is a boundary condition for modeling the room acoustic field. However, it is not easy to measure the acoustic impedances of the entire room because it requires many measurement points near the wall surface. Recently, a method to estimate the acoustic impedance and absorption coefficients by using both measurement and simulation methods has been proposed. However, a large number of measurement points are required to obtain sufficient estimation accuracy. In this study, we propose an estimation method of the sound absorption coefficients using machine learning by virtually increasing the number of microphones. First, the transfer functions at the virtual microphones are obtained for a small number of transfer functions based on the sound field modeling using sparse equivalent sources. Subsequently, both transfer functions at the virtual and actual microphones are used as the training data for machine learning. To evaluate estimation accuracy of the proposed method, we conducted the two-dimensional simulation experiments based on the boundary element method. [ABSTRACT FROM AUTHOR]

In hot and humid tropical countries, the houses are designed to be naturally ventilated with vent louvers. However, these louvers play as direct paths for noise entering the house. It is necessary to create geometries that can maximize the noise transmission loss and the ventilation performance of the housing structure. This study aims to develop ventilation and sound-absorbing material that can be 3D printed and installed on the upper part of the buildings' windows. The multi-objective optimization method was applied to generate 3D model specimens based on fluid potential flow analysis. To examine the absorption coefficient of the cylindrical specimens made of ABS filament with different filling rates manufactured by the 3D printer, the experiments were conducted in an anechoic chamber using an impedance tube that can measure the absorption coefficient in a frequency range of 300 to 2000 Hz. It was found that the sound absorption coefficient was little affected by the filling rate of ABS filament and improved effectively at a high-frequency range when adopting the optimized spiral structure. The improvement of sound absorption coefficient at frequency of about 800 Hz and the performance of multiple-structural material will be further considered in the next study phase. [ABSTRACT FROM AUTHOR]

The application of semiconductors has caught the interest of researchers because of the possibility to design structures with different geometrical shapes and sizes by varying the physical properties. The optical properties are one of the physical properties of the semiconductor. It provides an important tool for studying energy band structure, impurity levels, excitons, localized defects, lattice vibrations, and certain magnetic excitations. Mostly, researchers improving these properties experimentally. This gap makes an opportunity to explore the new design of semiconductors based on the optical properties theoretically. The aim of the reported work was to study the optical properties in the spherical quantum dot confined in the Deng fan Yukawa potential. The Schrödinger equation for Deng Fan Yukawa potential was solved using the NUFA method to obtain the analytical expressions of the eigen energies and the eigenfunctions. The eigenfunction which was a function of the energy spectra was determined from the eigenfunction equations and the calculated energy spectra. By applying the eigen energies and wave functions, the linear, the third-order nonlinear changes in absorption coefficients and refractive index were investigated using the density matrix formalism. The result shows that the non-relativistic energy spectra of the system increase by the increase of the principal quantum number and it is also seen that the energy spectra increase by the decrease of the inter-nuclear distance. The susceptibility coefficients, the absorption coefficient, and the change of the refractive index were determined and it can be visualized using computational programming for future analysis. [ABSTRACT FROM AUTHOR]

The polymer nanocomposites (PVA-ZnO) were prepared by adding different concentrations nanoparticles with weight ratios (0, 1, 3, 5, 7 wt %) in a polyvinyl alcohol mixture using the casting method for studying their optical characteristics. The results of transmittance and absorbance spectra were recorded in the wavelength range (190-1100) nm. The effect of the weight ratio of the ZnO nanoparticles on the optical parameters (transmittance, absorption coefficient) of polymer composite (ZnO-PVA) has been studied, The practical results showed that transmittance of polymer composites films (ZnO-PVA) decreases with the increase of the weight ratio of (ZnO) NPs, while the absorption coefficient increases with increasing the weight ratio of the (ZnO) NPs. The results also revealed that electronic transitions are indirect, and that the energy gap decreases with increasing the weight ratio of the (ZnO) NPs, while Urbach's energy increases with the increase of the weight ratio of nano (ZnO). The Fourier transform infrared spectrum showed the presence of (Zn-O) group in the (PVA-ZnO) nanocomposites. [ABSTRACT FROM AUTHOR]

Films of Undoped SnS and SnS:Cr have been prepared by using CSP method. From XRD patterns it is found that the prepared films are hexagonal wurtzite with a predominant peak (101) and the crystallite size is about (13. 28-15. 23) nm with Cr doping, whereas the strain decrease from 2. 58 to 2. 27 with Cr doping. AFM images show the Undoped SnS and SnS:Cr surface morphology. The average diameter was in the area of (82. 64), (67. 8) and (49. 75) nm for the (SnS, SnS:2% Cr and SnS:4% Cr) respectively. The surface roughness and rms values of the deposited films were (4. 78, 4. 18 and 1. 25) nm and (5. 83, 4. 06 and 2. 20) nm for SnS, SnS:2% Cr and SnS:4% Cr respectively. The transmittance of the film was observed to decrease for Cr doping, The decreasing in the optical energy gap which was found according to Tauc model were (1,48-1,37) eV, Results illustrate that both absorption coefficient and extinction coefficient of the films are increasing with increasing with Cr content in SnS thin films. The refractive index was found to decreased from 3,5-3,3 as the doping percentage increase. [ABSTRACT FROM AUTHOR]

The effect of annealing on the structural and optical properties of Antimony trisulfide (Sb2S3) is investigated. Sb2S3 powder is vaporized on clean glass substrates at room temperature under high vacuum pressure to form thin films. The structural research was done with the aid of X-ray diffraction (XRD) and atomic force microscopy (AFM). The amorphous to the polycrystalline transformation of these thin films was shown by X-ray diffraction analysis after thermal annealing. These films' morphology is explained. The absorption coefficient and optical energy gap of the investigated films are calculated using transmission spectra. Both samples have strong absorption in the visible spectrum, according to UV-visible absorption spectra. The optical band gap is measured using as-deposited Sb2S3 thin films at room temperature and annealed Sb2S3 thin films at 473 and 573 K. [ABSTRACT FROM AUTHOR]

The present investigation explains the consequence of irradiation of violet and red lasers on the optical properties of Cobalt dioxide (CoO2) thin films. The film was prepared by employing semi-computerized spray pyrolysis technique (SCSPT), when the received films were processed by continuous violet laser (405 nm) with power (1W) and red laser (700nm) with power (1000mW) for different laser irradiation time (0, 30, 45, 60, 75, 90 min) respectively at room temperature. The optical properties of CoO2 thin films was effected by laser irradiation. Where the parameters such as the absorbance, coefficient of absorption coefficient of extinction refractive index, optical conductivity, the real 휀1 and imaginary 휀2part of the dielectric constant of the films rises subsequently by laser irradiation, only the transmittance was decreased with laser irradiation time. The optical energy gap CoO2 was decreased from (1.98eV) to (1.52eV) after violet laser irradiation. While it changed from (1.91 eV) to (1.57eV) after red laser irradiation in different time and there is a great alteration of optical energy gap values for photovoltaic (PV) utilization. This result due to laser irradiation worked as heat treatment to enhance the crystallization of the deposited films. And the results showed that the laser irradiation process has a clear change in the optical properties with less time and energy than the traditional annealing methods which is the aim of this study. [ABSTRACT FROM AUTHOR]

The existing investigation explains the consequence of irradiation of red laser on the optical properties of Mawsonite Cu6Fe2SnS8 [CFTS] thin films. The film was equipped by the utilization of semi-computerized spray pyrolysis technique (SCSPT), it is the first time that this technique is used in the preparation and irradiation using a laser. From the XRD analysis, the crystalline existence with tetragonal crystal system was when the received films were processed by continuous red laser (700nm) with power (>1000mW) for different laser irradiation time using different number of times a laser scan (0, 6, 9, 12, 15and18times) with total irradiation time(0, 30, 45, 60, 75, 90 min) respectively at room temperature. The optical properties of mawsonite thin films was struck by laser ray of light. The parameters such as the absorbance, coefficient of absorption coefficient of extinction refractive index, optical conductivity, the real ε1 and imaginary ε2 part of the dielectric constant of the films rises subsequently by laser irradiation, only the transmittance was decremented with laser ray of light. The optical energy gap was reduced from (1.73eV) without irradiation to (1.56eV) and subsequent laser irradiation, and there is a great alteration of optical energy gap values for photovoltaic (PV)utilization. This result due to laser irradiation worked like annealing temperature to enhance the crystallization of the deposited films. And the results showed that the laser irradiation method has a clear change in the optical properties with less time and energy than the traditional annealing methods which is the aim of this study. [ABSTRACT FROM AUTHOR]

Graphene, renowned for its unique structure, exceptional electronic properties, and high mechanical strength, has been a focal point of research since its discovery. In this study, we investigate the structural, electronic, and optical properties of a zig-zag graphene nanoribbon using first-principle density functional theory (DFT). A simple graphene nanoribbon comprising 24 carbon atoms arranged in a zig-zag pattern is designed and optimized using the software "Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA)." The structural analysis of the designed system includes a detailed examination of bond lengths, bond angles, cell volume, and atomic packing fraction. To delve into its electronic properties, we conducted an investigation of the Density of States (DOS) and Partial Density of States (PDOS), providing insight into the material's electronic behavior. We also explore the possible mechanism behind the origin of the bandgap. While graphene is typically a zero bandgap material, our study reveals that the zig-zag pattern induces a bandgap of approximately 0.7 eV. Charge distribution analysis confirms the presence of covalent bonds between the carbon atoms. Furthermore, the optical properties of the graphene nanoribbon were analyzed, focusing on the absorption coefficient and optical conductivity. This comprehensive optical analysis provides valuable information for potential applications in optoelectronic devices. This work presents a systematic study aimed at enhancing the understanding of graphene nanoribbons with bandgaps, highlighting their potential for application-based research. The findings contribute to the ongoing development of graphene-based technologies, emphasizing the material's versatility and adaptability in various technological innovations. [ABSTRACT FROM AUTHOR]

We study the electronic structure, magnetic and optical properties of rare earth based ErPtSb half Heusler (HH) compound using first-principle density functional theory. Our calculated electronic band structure reveals the half-metallic character of the ErPtSb compound. The total density of states (DOS) and partial density of states (PDOS) of ErPtSb shows that the maximum contributions close to Fermi level (EF) is due to the Er-4f, Pt-5d and admixture of Sb-5p states. Whereas Er-4f unpaired electrons is mainly contributed in total magnetic moments of this compound. Optical response of the ErPtSb HH compound is investigated by optical parameters such as complex dielectric constant ε (ω), extinction coefficient κ (ω), absorption coefficient A (ω), and refractive index η (ω), with the function of photon energy. [ABSTRACT FROM AUTHOR]

Ga2O3:CdO films were deposited using pulsed laser deposition (PLD) of 500mJ laser energy on quartz substrates. The influence of Cadmium oxide on the optical properties (transmittance , absorbance, reflectivity, optical energy gab , dielectric constant, extinction coefficient, absorption coefficients and refractive index) of gallium oxide have been studied. The bandgap of the films was found to be (4.75 eV,4.65 eV,4.64 eV,4.5 eV and 2.8 eV)for (0% , 25wt,50%wt,75%wt and 100%) which decreased with increase of CdO concentration. Increasing of CdO concentration contributes to improving the optical properties of Ga2O3 where the transmittance value of 75%wt is 70%, and this is useful in opto-electrical devices. [ABSTRACT FROM AUTHOR]

A rapid, simple and accurate spectrophotometric method has been developed for atenolol determination in its pure and pharmaceutical form Novaten. This method is based on the formation of ion duplication complex between ATL and the phenol red reagent RPH to give a purple-colored product, which gave the highest absorption at 558 nm wavelength. The optimum conditions required for the formation of the complex were found (optimum dye concentration, the effect of acidity function, time, temperature, and the ratio of the complex binding), and the linearity of the complex ranged between 10 - 100 µg / mL and the molar absorption coefficient is 2.556×103 L / mol.Cm and Sandell indication 0.1041 µg / cm2, detection limit 0.1253 µg/ml, quantitative limit 0.4178 µg/ml, the percentage recovery, (100.8853 - 102.8385)%, and the rate of relative standard deviation RSD% (0.0994 - 0.1829)%. Based on the obtained results, the method is accurate compatible, and can be applied successfully to estimate ATL in the pharmaceutical drug Novaten by direct and standard additions methods. [ABSTRACT FROM AUTHOR]

The research dealt with developing a spectroscopic method for estimating the isoniazid drug through copper complexes formation for Schiff bases. The drug was reacted with aldehyde (para chloro benzaldehyde) and the preparation of a Schiff base then reacted it with copper chloride, where it showed the highest absorbance at a wavelength (336nm) and reached the limits of linearity Between (1-10 µg/mL). The correlation coefficient of R (0.9977), and the value of the molar absorption coefficient (1.6087×104) L / mol. cm, while the detection limit (0.1570), Sandell index (0.00852) µg/cm3, ratio % (99.300%), RSD% (0.172%). The method was successfully applied for the determination of isoniazid, and it was found that the results of the method are consistent with the concentration of content in pharmaceutical preparations. [ABSTRACT FROM AUTHOR]

The existing investigation explains the consequence of irradiation of violet laser on the optic properties of MawsoniteCu6Fe2SnS8 [CFTS] thin films. The film was equipped by the utilization of semi-computerized spray pyrolysis technique (SCSPT), it is the first time that this technique is used in the preparation and irradiation using a laser. From the XRD analysis, the crystalline existence with tetragonal crystal system was when the received films were processed by continuous violet laser (405 nm) with power (1W) for different laser irradiation time using different number of times a laser scan (0, 6, 9, 12, 15 and 18 times) with total irradiation time(0,30,45,60,75,90 min) respectively at room temperature. The optical properties of mawsoniteCu6Fe2SnS8 [CFTS] thin films was struck by laser ray of light. The parameters such as the absorbance, coefficient of absorption coefficient of extinction refractive index, optic conductivity, the real El and imaginary E2part of the dielectric constant of the films rises subsequently by laser irradiation, only the transmittance was decremented with laser ray of light. The optical energy gap was reduced from (1.71eV) without irradiation to (1.5eV) and subsequent laser irradiation, and there is a great alteration of optical energy gap values for photovoltaic (PV) utilization. As the results showed that the laser irradiation method has a clear change in the optical properties with less time and energy than the traditional annealing methods, this is the aim of the study. [ABSTRACT FROM AUTHOR]

A third order nonlinear optical single crystals of Triglycine Sulpho Succinate (TGSSu) has been grown by slow cooling method. The grown crystals were characterized using X-ray diffraction analysis technique and its found the grown crystals in monoclinic structures.Thermal analysis of TGSSu crystal were carriedout and its compared to TGS crystal. The second harmonic generation efficiency was studied Kurtz-Perry powder technique. The third-order nonlinearities of grown crystals have been investigated by Z-scan method. Nonlinear refractive index (n2), the nonlinear absorption coefficient (β) and third-order nonlinear susceptibility (χ(3)) were estimated for the sample. The results were discussed in detailed. [ABSTRACT FROM AUTHOR]

The effect of adding different volume of coumarin dye (5, 15, 25 and 35) ml on optical properties of Poly (Methyl Meth Acrylate) was studied. Films of pure PMMA and PMMA with different volume of coumarin dye (5, 15, 25 and 35) ml were prepared using the casting technique. Transmission and absorption of the films were measured by using UV-VIS spectrometer technique type (100 Conc), in order to assess the type of transmission which was found an indirect transition. An optical energy gap of pure PMMA is (4.95e v) and after adding coumarin with volume (25, 35) ml, the energy gap for PMMA decrease by (0.05) compere to pure PMMA films and addition energy gap appear equal to (4.1 e v). It was found that the absorption coefficient, extinction coefficient and dielectric constants increasing by addition coumarin. [ABSTRACT FROM AUTHOR]

A mathematical tool was developed for monitoring, predicting the concentration of harmful substances in the sur-face layer of the atmosphere of industrial regions for making a managerial decision to protect them from techno-genic factors. Since one of the main factors in the change of the concentration of harmful substances in the atmosphere is aerosol particles, then when conducting a comprehensive study on their distribution, their velocities mixed in the boundary layer of the atmosphere are taken into account with their physical and mechanical properties. In the article, on the basis of the proposed mathematical tool, numerical calculations on a computer were performed and, based on their analysis, it was established that with an increase in the intensity of aerosol generators and horizontal components of wind speed, the propagation area of the concentration of aerosol particles in the atmosphere increases. A detailed analysis of numerical calculations showed that the change in the concentration of aerosol particles in the atmosphere is affected by the coefficient of absorption of aerosol particles, which changes depending on the moisture content of the airmass of the atmosphere; the vertical rate of deposition of particles, which depends on the mass, shape and density of aerosol particles; the coefficient of turbulence that depends on the roughness of the earth's surface. [ABSTRACT FROM AUTHOR]

The article substantiates the need to switch to wireless channels of the optical range for communication with mobile objects. The relevance of the topic is due to the growing need to increase the speed of information transfer. This is due to the introduction of unmanned technologies in railway transport, which involve a constant exchange of data between the rolling stock and the traffic control center. The limited capacity of radio channels does not allow remote control of trains. This problem can be solved by switching communication channels with mobile objects to the optical wavelength range. To implement projects for the introduction of wireless optical communication, it is necessary to ensure the required range and quality of communication. This problem can be solved by increasing the optical budget of the wireless optical communication channel (BOX) by increasing the sensitivity of the photodetectors and the corresponding signal-to-noise power ratio. This way is more rational than increasing the laser power. For this purpose, the article proposes to use new nanoelectronics materials based on enriched semiconductors. As evidence, the results of studies of the influence of the concentrations of heavy isotopes on the band gap of semiconductors, as well as the light absorption coefficients and quantum efficiency are presented. Calculation of the communication quality in the form of the error probability of an elementary pulse at the output of the photodetector showed that enriched materials in the form of multiple quantum wells provide the error probability by two orders of magnitude less than natural semiconductors. Thus, the obtained gain in the signal-to-noise ratio at the output of the photodetector due to new materials can be used: a) to improve the quality of communication, which is important in conditions of atmospheric interference; b) to increase the communication range, which is important for a moving object. [ABSTRACT FROM AUTHOR]