Values Of Transmission Coefficients Research Articles

Analytical Approach of Wave Transmission Coefficient through on Composite Hanging Breakwater

Conventional breakwater like a rubble mount is require large infestation, especially when that structure construct in deep water. Currently, innovations are needed to solve financial problems in building breakwaters. Composite hanging breakwater is proposed as a new solution in marine structure. Composite hanging breakwater made by both of stone and concrete or steel material consist of two-part are structural part and filler. Structural parts are piles, beams, and brackets made of concrete or steel. Filler material using of stone or other material. This structure has the advantage are cheaper than conventional breakwater, precast material, and the diameter of stone filler is relatively small. Until now, the performance of composite hanging breakwater is unknown. Commonly, the key performance indicator of breakwaters is wave transmission and represent by the waves transmission coefficient. Therefore, in this study, an analytical equation of wave transmission coefficient was developed using the conservation of energy concept. Based on this equation shows that the wave transmission coefficient is influenced by both structure and wave parameter. After the equation has been obtained, then it is compared with previous research. Research that has been used as a comparison includes research by Weigel (1960), Abul-Azm (1993), Liu and Abbaspour (1982), Abu-Azm (1993), Heikal (1997), Koraim (2005), Rage and Koraim (2010), and Koraim (2014). Wave parameter represents by waves steepness implicitly, and structure parameter is represented by the permeability of structure, relative length, and relative depth. The greater the value both of relative depth and length, the smaller value of wave transmission coefficient. The greater the value of structure permeability, the smaller the value of wave transmission coefficient. When the D/h is zero, the wave transmission coefficient is equal to one and when the D/h is equal to one, the transmission coefficient is close to or equal to zero. When the D/h value is less than 0.5, the Kt value in this present study is lower than the Kt value in previous studies for the same D/h value, and when the D/h value is greater or equal to 0.5 then the Kt value is close or the same with the previous study.

UWB-Mimo antenna of high isolation two elements with wlan single band-notched behavior using roger material

A highly isolated MIMO antenna is proposed for Ultra-wide band (UWB) applications. The proposed MIMO antenna structure consists of two rectangular shaped monopole antennas placed alongside each other on the same substrate. The structure of the identical radiators shaped as simple four open loop cutting at the end of the patch. The proposed antenna is designed to operate at the UWB frequency range from 2.5 GHz to 13.5 GHz. Moreover, a single band notched feature has the spectrum range from 5 GHz to 6 GHz for IEEE802.11 (WLAN) and it is realized by loading an open loop slot in the radiator to minimize the interference. The reflection and transmission coefficient values are below than −10 dB and −25 dB respectively within the UWB frequency range. Furthermore, by embedding a simple rectangular stub between two monopole patch antenna elements, reduce mutual coupling and thus its control the utilization of bandwidth and radiation. Radiation can also be reduced by using roger semiconductor materials. As well as, designed MIMO-UWB antenna has a good impedance matching between measured and simulation results which enhance the isolation to achieve a high signal strength.

Millimeter-Wave Double Ridge Gap Waveguide Six-Port Network Based on Multi-Via Mushroom

In this article, a six-port network using double ridge gap waveguide based on the multi-via mushroom (M-DRGW) is proposed at millimeter-wave frequency band, which covers the 5G N260 frequency range. First, the stopband of the multi-via mushroom unit cell has been analyzed. Then, simplified schematic of the six-port network is given, and the power divider/coupler based on the M-DRGW is designed to form the six-port junction. For measurement, the peripheral test circuit of the M-DRGW six-port junction is added, and the transitions between the ridge gap waveguide (RGW) and hollow waveguide are added. For the comparison with the performances of the proposed M-DRGW six-port network, the one based on the traditional metallic double RGW (DRGW) has also been designed, fabricated, and measured. The simulated and measured results show that the phase differences between port 1/2 and four output ports are within ±2.5° and ±5°, respectively, and the average value of transmission coefficient is around −8 dB.

Wave Transmission Analysis on Hexagonal Shape Floating Breakwater

Coastal areas have many benefits for activities, such as port construction, fishing activities, recreation areas, resource utilization, alternative energy-producing places, etc. However, many factors limit this use due to water wave activity, such as storm surges and the potential for tsunamis. These factors also cause abrasion and coastal erosion that can damage the coastal environment. To overcome this problem, it can be done by building a coastal protective structure, one of which is a floating breakwater. In this study, analysis of wave transmission on a hexagonal floating breakwater will be carried out to determine the effectiveness of its performance. The wave transmission test on the floating breakwater was carried out with variations of irregular waves (Jonswap spectrum) and mooring angles. The position of the wave probe is set at 100 cm and 220 cm behind the structure. The largest transmission coefficient occurs at a mooring angle of 30 o in both scenario 1 and scenario 2. The smallest transmission coefficient value is at an angle of 60 o in both scenarios of wave probe placement. The plotting results show that the transmission coefficient is directly proportional to the period and height of the incident wave and vice versa the transmission coefficient is inversely proportional to the steepness of the wave

Metamaterial optical filter with maximal absorption coefficient

Tunable transmission and absorption coefficients in visible and infrared range have been obtained for metamaterial filters with a structure of metal on dielectric nanocomponents. Materials were stacks of nanoconstituents placed in alternate layers, which present a maximum or a minimum of the transmission coefficient and convenient values of the absorption coefficient when the periodicity is interrupted in a controlled manner. A simulational set-up with the metamaterial sample in a channel waveguide was conceived for obtaining the S parameters at the field propagation, using the HFSS program. The plasmon dispersion at the metal / dielectric interface was taken into account for calculating the frequency dependent surface plasmon wave vector, which can be adjusted by modifying the refractive index and the electric permittivities of the constituents. Transmission coefficients have been calculated for different structure geometries. The optimal metamaterial configurations have been chosen, in function of the desired filtering effect, for a range of incident field wavelength of 600 – 900 nm. A transmission variation of about 50 … 80 % at the central frequency, in comparison with the transmission effects in the side bands has been demonstrated for the proposed metamaterial filters.

Dissipative optomechanical coupling with a membrane outside of an optical cavity

We theoretically study an optomechanical system, which consists of a two-sided cavity and a mechanical membrane that is placed outside of it. The membrane is positioned close to one of its mirrors, and the cavity is coupled to the external light field through the other mirror. Our study is focused on the regime where the dispersive optomechanical coupling in the system vanishes. Such a regime is found to be possible if the membrane is less reflecting than the adjacent mirror, yielding a potentially very strong dissipative optomechanical coupling. Specifically, if the absolute values of amplitude transmission coefficients of the membrane and the mirror, $t$ and $t_m$ respectively, obey the condition $ t_m^2< t\ll t_m\ll 1$, the dissipative coupling constant of the setup exceeds the dispersive coupling constant for an optomechanical cavity of the same length. The dissipative coupling constant and the corresponding optomechanical cooperativity of the proposed system are also compared with those of the Michelson-Sagnac interferometer and the so-called "membrane-at-the-edge" system, which are known for a strong optomechanical dissipative interaction. It is shown that under the above condition, the system proposed here is advantageous in both aspects. It also enables an efficient realization of the two-port configuration, which was recently proposed as a promising optomechanical system, providing, among other benefits, a possibility of quantum limited optomechanical measurements in a system, which does not suffer from any optomechanical instability.

Pengaruh Konfigurasi Terumbu Buatan Bentuk Heksagonal pada Kemampuan Peredaman Gelombang

An artificial reef is a structure that is placed underwater and functions as a natural coral reef. Apart from being an artificial reef, the function of artificial reefs is also as a submerged breakwater. As a breakwater, it is necessary to know the level of effectiveness in reducing waves and the impact of scouring arising from the laying of artificial reef structures. This research was conducted to determine the correlation between the ability of wave attenuation to the depth of scouring due to variations in laying (structure gap distance) and variations in waves on artificial reefs in hexagonal shape with a scale model of 1:10. From the results of research conducted at the Marine Energy Laboratory of the Department of Marine Engineering, FTK ITS obtained, for laying structures with a gap of 1D, they have better wave attenuation capabilities with a small maximum scouring depth, namely with a Kt value of 0.844 and a scouring depth of 3 cm. For the laying of the structure with a distance of 0D, it has a greater value of transmission coefficient (Kt), which is 0.911 with a greater value of the maximum scouring depth, which is 3.5 cm.

Transmittance on combinatorial structures of triple potential barriers

Semiconductor materials used as potential barriers in the study are GaAs, GaSb, and AlAs. These materials will be arranged in certain combinations to form triple potential barrier structures and the effect of combinations will be analysed against transmission coefficient values. In this study, the maximum energy of the electron is 1 eV and the matrix propagation method is used where the effect of the combinations structure on transmission coefficient values is numerically analysed using a computational program. The results showed that the structuring potential barrier affects the value of the transmission coefficient. In the uniform barriers arrangements, the value of the transmission coefficient decreases with increasing potential barrier energy. Whereas in the arrangement of different barrier combinations, two opposing combination arrangements have the same transmission coefficient values. Thus, from six combination arrangements, there are three kinds of transmission coefficient values. The maximum transmission coefficient value is 1.000 in the triple potential barrier of GaSb at 0.49 eV. Research on the tunnel effect contributed to the development of electronic and optoelectronic devices such as transistors and lasers.

Transmission Coefficient Analysis of Notched Shape Floating Breakwater Using Volume of Fluid Method: A Numerical Study

As one of the coastal structures, breakwaters are built to protect the coastal area against waves. The current application of breakwaters is usually conventional breakwaters, such as the rubble mound type. Climate change, which causes tidal variations, sea level height, and unsuitable soil conditions that cause large structural loads, can be solved more economically by employing floating breakwater. In this study, numerical simulations will be conducted by exploring the optimum floating breakwater notched shapes from the Christensen experiment. The comparison of three proposed floating breakwater models, such as square notch (SQ), circular notch (CN), and triangular notch (VN), is compared with standard pontoon (RG) to optimize the transmission coefficient value is analyzed. Numerical simulations are conducted using Computational Fluid Dynamics (CFD) based on the VOF method with Flow 3D Software. Compared to the experimental study, the RG model's validation shows a good result with an error rate of 8.5%. The comparative results of the floating breakwater models are found that the smaller the transmission coefficient value, the more optimal the model. The SQ structure has the smallest transmission coefficient of 0.6248. It can be summarized that the SQ model is the most optimal floating breakwater structure.

The Analysis of Light Intensity Transmission Coefficient Through Plastic Fibers for the Design of Closed Room Lighting without Electricity

The phenomenon of total internal reflection can be used to guide the light to be transmitted from one place to another, it is applied to the guiding principle of light in fiber optics. A fiber rope made of clear plastic material with a uniform refractive index, when one end fired a beam of light then the light will be forwarded along the strap so that out at the other end. This principle can be applied as a lighting source in a closed room by passing light from the outdoors by using plastic fiber, so it doesn’t need the electricity. In this study, theoretical analysis of the percentage of the intensity of light transmitted by the fiber plastic succeed as a function of the refractive index and determine the transmission coefficient for some plastic seeds are eligible to be used as a plastic fiber light successor. From the results of deriving the equation, the light transmission coefficient of plastic is and the terms of plastic seeds that can be used as a plastic fiber are having a refractive index . Based on refractive index data from profesionalplastics, the maximum transmission coefficient value for Ethylene Tetrafluoro Ethylene Copolymer is 82.23% and the minimum transmission value of Fluorinated Ethylene Propylene Copolymer is 55.99%.

Analytical study of wave diffraction by an irregular surface located on a flexible base in an ice-covered fluid

The reflection and transmission of surface waves propagating over an irregular surface located on a flexible base in an ice-covered fluid are analyzed within the context of linearized water wave theory. The ice-floe and flexible bed surface are assumed as narrow elastic sheets with different compositions. Under such circumstances, there are two types of proliferating waves that exist for any specific frequency. The proliferating waves having smaller wavenumber spread at just beneath the ice-floe (ice cover mode) and the other spreads over the flexible bottom of the fluid (flexural base mode). An elementary perturbation theory is used for reforming the governing boundary value problem (bvp) to a first-order bvp which is solved by utilizing the Green’s function technique. The first-order correction of the reflection and transmission coefficients are calculated in the form of integrals comprising of a function which represents the base deformation. A particular example of base deformation is taken to evaluate all these coefficients and the results are depicted graphically. The major strength of the recent study is that the results for the values of reflection and transmission coefficients for both the wavenumbers are established to meet the energy relation almost exactly.

FIRST MICROWAVE TOMOGRAPHY APPROACH TOWARDS A TRULY NONINVASIVE, PAIN-FREE AND WEARABLE BLOOD GLUCOSE MONITORING DEVICE

Despite the advancements in the field of glucose monitoring sensors, the development of noninvasive, wearable, continuous and comfortable systems is still a real challenge. New technologies are required for noninvasive, continuous and effective measurements remaining discreet, painless, comfortable to the patient and avoiding additional costs. This article presents a truly noninvasive microwave tomography prototype designed for glucose monitoring. The system is based on an array of dipole antennas placed in a circular configuration. The transmitted field data are collected using a switch matrix connected to a vector network analyzer. A heterogeneous 3-D arm model and a 3-D electromagnetic solver have been used to model the human arm and to characterize the system. Blood electromagnetic properties are affected by the glucose concentration, a promising correlation between the dielectric properties of blood and glucose level should be investigated. By simulating the antenna array on the arm phantom, the characteristics of the S-parameters were interesting at the frequencies of interest. The transmission coefficient amplitude decreases as the dielectric constant decreases from 63 to 40, and the conductivity increases from 1.5 S/m to 3.5 S/m. For each value of dielectric properties, a given transmission coefficient value can be clearly identified. Experimental measurements validated the arm phantom and confirmed the relationship between the response of the system and the dielectric properties of blood tissue. The armband sensor is designed as an inexpensive, noninvasive, and light weight device suitable for all patients with a high level of discretion. This work, under optimization for preclinical and clinical testing, demonstrates the proof of concept of an innovative microwave tomography system for noninvasive glucose monitoring. Compared to studies with a similar aim, this research may achieve distinct advances and offers promising hope in the field of noninvasive glucose sensors.

Tunnelling Effect for Quadruples Potential Using Matrix Propagation Method

Semiconductor materials can be used as potential barriers to Tunnelling effects. In this study, four semiconductor materials are arranged in various ways to form a quadruple potential structure to analyze the value of the transmission coefficient. The analysis was conducted using the analytical and numerical matrix propagation method using Matlab2018a. The results confirmed that the inverted arrangement produces the same transmission coefficient value for each energy. So that there are 12 kinds of transmission coefficient values generated from 24 arrangements. The semiconductor material composition with the most considerable transmission coefficient value is ADCB and BCDA, which have a value of 0.8087. The variation of the arrangement affects the value of the transmission coefficient so that it can be used as a guideline for selecting the arrangement that produces the most optimum value of the transmission coefficient from various possible arrangements.

The temperature induced current transport characteristics in the orthoferrite YbFeO3− δ thin film/p-type Si structure

The perovskite ytterbium ferrite is a new ferroelectric semiconductor material. We presented the temperature induced current–voltage (I–V) characteristics of the Al/YbFeO3−δ /p-Si/Al hetero-junction. The orthoferrite YbFeO3−δ thin films were deposited on a single crystal p-type Si substrate by a radio frequency magnetron sputtering system. The potential barrier height (BH) and ideality factor n of the heterojunction were obtained by thermionic emission current method based on the recommendations in the literature. The fact that the calculated slopes of I–V curves become temperature independent implying that the field emission current mechanism takes place across the device, which has been explained by the presence of the spatial inhomogeneity of BHs or potential fluctuations. Moreover, a tunneling transmission coefficient value of 26.67 was obtained for the ferroelectric YbFeO3−δ layer at the Al/p-Si interface.

Justification of binder material selection for carbon particles incorporation into fibrous electromagnetic radiation absorber

The paper presents justification of a binder material for incorporating carbon particles into the interfiber space of electromagnetic radiation absorber. A method for carbon particles incorporation into a fibrous material has been developed. It is based on applying a carbon-containing nanocomposite to the fibrous material’s surface. Previously, the research of carbon particles incorporation into a synthetic material by using an aqueous solution were carried out, which ensured a uniform distribution of carbon particles in the material structure. However, the properties of the material have changed significantly upon mechanical deformation. Therefore, the carbon particles incorporation process was investigated using various nanocomposites obtained on the basis of mixtures of vinyl acetate polymer, or epoxy polymer, or surface-active substance with carbon black. Based on the results of electron microscopic analysis and the reflection and transmission coefficients frequency dependences in the frequency range 0.7–17 GHz, the efficiency of using a nanocomposite based on a mixture of surface-active substance and carbon black to create electromagnetic radiation absorbers was justified. Such electromagnetic radiation absorbers have the transmission coefficient value about –18 dB and reflection coefficient value about –12 dB in the frequency range 7–13 GHz. Carbon-containing electromagnetic radiation absorbers based on fibrous material have thickness less than 3 mm, properties of flexibility and resistance to mechanical deformation. It can be used in various fields, in particular for hiding objects from radio frequency reconnaissance or protecting equipment from external interference.

Laboratory investigation on hydraulic performance of enlarged pile head breakwater

Coastal erosion of beaches has been a common problem around the world. One of the eco-friendly control measures for coastal erosion is to dissipate the energy of waves impinging on the shores by constructing offshore breakwater. Pile breakwater is one such type of offshore breakwater that consists of a number of closely spaced piles. Construction of piles at closer spacing is highly challenging and expensive. This problem can be addressed by reducing the number of piles and modifying the pile with an enlarged head in the vicinity of the water surface, where wave energy is concentrated. In the present study, an experimental investigation on the hydraulic performance of enlarged pile head breakwater is conducted in a wave flume. The concept breakwater is subjected to monochromatic waves of varying wave heights, wave periods and water depth. The experimental results show that the least value of transmission coefficient is 0.62 and reflection coefficient is 0.123 with the highest value of dissipation coefficient of 0.77 for the structural configuration of b/D ratio of 0.2, D/Hmax of 0.6 and Y/Hmax of 1.0 at a water depth of 0.3 m. Observed results are encouraging and are in line with the similar type of pile breakwaters in a single row. The present experimental data is also validated with the available theoretical solutions. Since the results from the compared theoretical solution are not in good agreement, a hybrid theoretical model is reconstructed based on experimental results of pile head breakwater. The proposed modified version of the hybrid equation predicts encouragingly better transmission, reflection and dissipation coefficient than the existing solutions. Moreover, the results predicted by the proposed hybrid equation are in good agreement with that of other similar pile breakwater models.

Scattering of linear oblique water waves by an elastic bottom undulation in a two-layer fluid

A hydrodynamic model, with incorporation of elasticity, is considered to study oblique incident waves propagating over a small undulation on an elastic bed in a two-layer fluid, with the upper layer exposed to a free surface. Following the Euler–Bernoulli beam equation, the elastic bed is approximated as a thin elastic plate. The surface tension at the interface of the layers is completely ignored since its contribution will be minimal. While considering water waves passing over a deformable bottom, a significant change in the wave characteristics is observed due to the elasticity of the bottom which has an immense impact on the water wave kinematics and dynamics in addition to demonstrating the elastic behavior of the soil beneath. Time-harmonic waves propagate over an elastic bed with two different modes: the one corresponding to the smaller wavenumber propagates along the interface and the other one corresponding to the higher wavenumber along the free surface for any given frequency. Considering an irrotational motion in an incompressible and inviscid fluid, and applying perturbation technique, the first-order corrections to the velocity potentials are evaluated by an appropriate application of Fourier transform and, subsequently, the corresponding reflection and transmission coefficients are computed through integrals containing a shape function which depicts the bottom undulation. To validate the theory developed, one particular undulating bottom topography is taken up as an example in order to evaluate the hydrodynamic coefficients which are represented through graphs to establish the water wave energy conversion between those modes. The observation is that when the oblique wave is incident on the interface, energy transfer takes place to the free surface, but for free-surface oblique incident waves, no such energy transfer to the interface takes place because of the parameter ranges. It is noticed that reasonable changes in the elasticity of the bed have a significant impact when the propagating wave encounters a small elastic bottom undulation. Further, the values of reflection and transmission coefficients obtained for both the interfacial wave mode as well as the free-surface wave mode in the fluid are found to satisfy the important energy balance relations almost accurately. Such problems with a deformable bed, to be precise elastic here, will enable researchers to take up problems which take into account the characteristics of the infinite depth of soil beneath the bed, and the present study is expected to provide the necessary background.

Wave Transmission by Rectangular Submerged Breakwaters

In this paper, we investigate the wave damping mechanism caused by the presence of submerged bars using the Shallow Water Equations (SWEs). We first solve these equations for the single bar case using separation of variables to obtain the analytical solution for the wave elevation over a rectangular bar wave reflector with specific heights and lengths. From the analytical solution, we derive the wave reflection and transmission coefficients and determine the optimal height and length of the bar that would give the smallest transmission coefficient. We also measure the effectiveness of the bar by comparing the amplitude of the incoming wave before and after the wave passes the submerged bar, and extend the result to the case of n-submerged bars. We then construct a numerical scheme for the SWEs based on the finite volume method on a staggered grid to simulate the propagation of a monochromatic wave as it passes over a single submerged rectangular bar. For validation, we compare the transmission coefficient values obtained from the analytical solution, numerical scheme, and experimental data. The result of this paper may be useful in wave reflector engineering and design, particularly that of rectangle-shaped wave reflectors, as it can serve as a basis for designing bar wave reflectors that reduce wave amplitudes optimally.

Development of a Transient Model of a Lightweight, Portable and Flexible Air-Based PV-T Module for UAV Shelter Hangars

This research paper introduces a mathematical model to predict the performance of photovoltaic–thermal systems (PV-T), based on a thin layer flexible panel and an air pipe, by using the Trnsys® software tool to simulate energetic systems. The main advantage of these types of panels is their easy portability, making them ideal to address thermal needs in several scenarios. In the military field, there is an important concern about the use of sustainable energy; for instance, cooling facilities for infantry tents used in their deployments. In this research, a PV-T panel to cover electrical power needs for an infantry’s hangar unmanned air vehicle (UAV) is introduced. The proposed thermal model, based on the novelty of inertial mass (lump) as an approach to real panel behavior, has been validated through the comparison between Trnsys’ model simulation data, a real weather station, and data obtained in a test bed. Genopt’s simulation software is used to fit the model, allowing for the prediction of heat transmission coefficient values. The good match between simulated and experimental data makes the proposed model suitable for the photovoltaic–thermal prediction of panel behavior.

Pulsed laser deposition of aluminum nitride thin films onto sapphire substrates

Subject of Research. The paper presents experimental study results of surface morphology and structural and optical properties of sapphire AlN films obtained by pulsed laser spraying. Method. Thin AlN films on sapphire were used as experimental samples. The preparation of AlN films was carried out using a combined installation of ion-beam and pulsed laser radiation. The deposition process was performed by sputtering a rotating aluminum target with 532 nm wavelength AYG: Nd3+ laser in the atmosphere of very pure nitrogen at the pressure of 3 and 4 Pa. The energy density of the laser pulse was 4 J/cm2 with a pulse duration of 15 ns and a pulse repetition rate of 15 Hz. The distance from the target surface to the sapphire substrate was 50 mm; the substrate temperature was 600 °C. Main Results. Using scanning electron microscopy and energy dispersive analysis, it was found that AlN films obtained at the nitrogen pressure in a vacuum chamber of 4 Pa have a composition more related to stoichiometric than AlN films obtained at the nitrogen pressure in a vacuum chamber of 3 Pa. The optical spectroscopy was used to study the transmission spectra of the samples under research. It was determined that the maximum transmission coefficient values of AlN films obtained at the nitrogen pressure in the vacuum chamber of 3 Pa (95.12 %) and 4 Pa (97.65 %) are within the wavelength range of 400–410 nm. The transmittance in the studied wavelength range of 300–1100 μm is at least 87 %, which characterizes the obtained film samples as optically transparent. Practical Relevance. The studied thin AlN films can be used as a buffer layer in optoelectronic devices, including the case of creating light-emitting diodes based on GaN and AlxGa1–xN of short-wave visible light and white-emitting devices.