Value Of Reflection Coefficient Research Articles

침투 해저면 위의 투과잠제주변 파랑특성의 수치해석

In this study, wave characteristics coming with oblique incident angle to permeable trapezoidal submerged breakwater on the porous seabed are calculated by using boundary element method. This numerical analysis, based on the wave pressure function, is analyzing the continuity in the analytical region including fluid and structure. From the comparison of the reflection coefficients and damping coefficient, the results of this study are in good agreement with the existing results. The peak values of reflection coefficient obtained by permeable trapezoidal submerged breakwater on the porous seabed are smaller than those of permeable trapezoidal submerged breakwater on the non-porous seabed. The velocity vector in front of permeable trapezoidal submerged breakwater on the porous seabed is smaller than that in front of permeable trapezoidal submerged breakwater on the non-porous seabed with out the energy loss.

Fixed-order stabilising controller design by a mixed randomised/deterministic method

A novel mixed randomised/deterministic method for fixed-order controller design is proposed for discrete-time single-input single-output plants. It is based on the random generation of Schur stable polynomials using reflection coefficients and reflection segments of polynomials. Stable reflection segments are then projected onto the affine set of closed-loop characteristic polynomials and the stable line segments in the controller parameter space are determined. A novel approach is proposed for global and local optimisation over reflection segment bunches on the basis of the weighted sum of absolute values of reflection coefficients.

Survey of monoclonal antibody disposition in man utilizing a minimal physiologically-based pharmacokinetic model.

Minimal physiologically based pharmacokinetic (mPBPK) models provide a simple and sensible approach that incorporates physiological elements into pharmacokinetic (PK) analysis when only plasma data are available. With this modeling concept, a second-generation mPBPK model was further developed with specific accommodations for the unique PK properties of monoclonal antibodies (mAb). This study applied this model to extensively survey mAb PK in man in order to seek general perspectives on mAb distributional and elimination features. Profiles for 72 antibodies were successfully analyzed with this model. The model results provide assessment regarding: (1) predominant clearance site, in plasma or interstitial fluid (ISF); (2) mAb ISF concentrations in two groups of lumped tissues with continuous (V(tight)) or fenestrated (V(leaky)) vascular endothelium; (3) Transcapillary escape rate (TER), an indicator of systemic vascular permeability. For 93% of surveyed mAbs, the model assuming clearance from plasma (CL) produced better or at least equivalent model performance than the model with clearance from ISF and yielded most consistent values of vascular reflection coefficients (σ1 and σ2) among all antibodies. The average mAb ISF concentration in V(tight) and V(leaky) at equilibrium was predicted to be about 6.8 and 37.9% of that in plasma. A positive correlation was detected between plasma clearance and TER among most mAbs, which could be interpreted as both parameters having common determinants related to ISF tissue distribution in this model context. The mAbs with relative higher plasma clearance (>0.035 L/h/70 kg) did not reveal such positive correlation between clearance and TER, implying that the factors contributing to high clearance may not necessarily increase tissue distribution and penetration. In conclusion, this mPBPK model offers a more mechanistic approach for analyzing plasma mAb PK than compartment models and generates parameters providing useful intrinsic distributional and elimination insights for a large number of mAbs that were examined in man.

Quantification of signal and noise in two-way transmitted wavefields to improve well ties in Cooper Basin, Australia

Permian coal beds at 2400–2900 m depth in Cooper Basin, Australia have normal-incident reflection coefficient values as large as [Formula: see text]. If internal multiples are included in synthetic seismograms, excellent correlations exist between the synthetic seismogram and seismic, even when more than 50 coal beds are present. However, neither the synthetic seismogram nor the seismic tie the well-log lithologic boundaries because the incident wavefield that strikes a lithologic boundary and returns to the surface contains a signal wavelet followed by high-amplitude noise, which are interbed multiple reflections. Because the spectra of the signal and noise coda at a given two-way time normally do not overlap, time-varying Gaussian filters applied to the near-offset stack enhance the signal and suppress the noise coda. After filtering, the apparent time delay of reflections introduced by the coal beds is removed with variable time shifts (time compression), based on the estimated time-varying signal wavelets. The two-step process of low-pass filtering and compression yields seismic events that successfully tie the lithologic boundaries in the borehole, although with limited resolution. Our preliminary tests on a seismic line indicate that the horizon event associated with the base of a 500-m-thick coal sequence is more coherently imaged with our processing than with conventional processing.

The effects of grain boundary scattering on electrical resistivity of Ag/NiSi silicide films formed on silicon substrate at 500 °C by RTA

Abstract The temperature-dependent resistivity measurements of Ag/Ni-Si silicide films with 28–260 nm thicknesses are studied as a function of temperature and film thickness over the temperature range of 100–900 K. The most striking behavior is that the variation of the resistivity of the films with temperature exhibits an unusual behavior. The total resistivity of the Ag/Ni-Si silicide films in this work increases linearly with temperature up to a T m temperature, and thereafter decreases rapidly. Our analyses have shown that in the temperature range of 100 to T m °K, the parallel-resistor formula reduces to Matthiessen's rule and θ D (Debye temperature) have been found to be about 201–404 K for the films. The correlation of the Ag/Ni-Si silicide formation with its electrical and morphological properties is also established. We have also shown that for temperature range of 100– T m °K, linear variation of the resistivity of the silicide films with temperature has been caused by both grain-boundary scattering and electron-phonon scattering. That is why resistivity data could have been analyzed successfully in terms of the Mayadas–Shatzkes (M–S) model. Theoretical and experimental values of reflection coefficients have been calculated by analyzing resistivity data using the M–S model. According to our analysis, R increases with decreasing film thickness for a given temperature. For room temperature, theoretical and experimental reflection coefficients have been calculated to be R th = 0.264, R exp = 0.296 for the thinnest sample (28 nm). On the other hand, for the thick sample (260 nm), these reflection coefficients have been determined as R th = 0.027, R exp = 0.048.

Electromagnetic wave absorption properties of graphene modified with carbon nanotube/poly(dimethyl siloxane) composites

By using a catalytic growth procedure, carbon nanotubes (CNTs) are in situ formed on reduced graphene oxide (RGO) sheet at 600°C. CNTs growing on RGO planes through covalent C–C bond possess lower interfacial contact electrical resistance. As a hybrid structure, the CNTs/graphene (CNT/G) are well dispersed into poly (dimethyl siloxane). The hybrid combining electrically lossy CNTs and RGO, which disperses in electrically insulating matrix, constructs an electromagnetic wave (EM) absorbing material with ternary hierarchical architecture. The interfacial polarization in heterogeneous interface plays an important role in absorbing EM power. When the filler loading is 5wt.% and thickness of absorber is 2.75mm, the minimum value of reflection coefficient and the corresponding frequency are −55dB and 10.1GHz, and the effective absorption bandwidth reaches 3.5GHz. Therefore, combining the CNTs and graphene sheet into three-dimensional structures produces CNT/G hybrids that can be considered as an effective route to design light weight and high-performance EM absorbing material, while the effective EM absorption frequency can be designed.

AVO analysis of BSR to assess free gas within fine-grained sediments in the Shenhu area, South China Sea

Gas hydrates have been identified from two-dimensional (2D) seismic data and logging data above bottom simulating reflector (BSR) during China's first gas hydrate drilling expedition in 2007. The multichannel reflection seismic data were processed to be preserved amplitudes for quantitatively analyzing amplitude variation with offset (AVO) at BSRs. Low P-wave velocity anomaly below BSR, coinciding with high amplitude reflections in 2D seismic data, indicates the presence of free gas. The absolute values of reflection coefficient versus incidence angles for BSR range from 0 to 0.12 at different CMPs near Site SH2. According to logging data and gas hydrate saturations estimated from resistivity of Site SH2, P-wave velocities calculated from effective media theory (EMT) fit the measured sonic velocities well and we choose EMT to calculate elastic velocities for AVO. The rock-physics modeling and AVO analysis were combined to quantitatively assess free gas saturations and distribution by the reflection coefficients variation of the BSRs in Shenhu area, South China Sea. AVO estimation indicates that free gas saturations immediately beneath BSRs may be about 0.2 % (uniform distribution) and up to about 10 % (patchy distribution) at Site SH2.

Structure of shock waves with emission in a gas flow impinging on a barrier

The parameters of emitting shock waves generated upon high-velocity rarefied-gas flow impingement on a plane barrier are investigated with account for the reflecting capacity of the barrier. In the case of aluminum plasma impingement the unsteady radiation-gasdynamic flows are numerically calculated using the Lax-Wendroff scheme at different values of the radiation reflection coefficient. The radiation transport is accounted for in the gray gas approximation. In the quasi-stationary stage the structure of compressed shock layer on the wall is considered in the radiant heat conduction approximation.

MINIMIZATION OF THE NUMBER OF INFORMING SIGNS WHEN CONSTRUCTING THE CLASSIFIER OF VEGETABLE OBJECTS

In the article a possibility is considered as to decrease information features at discrimination of vegetable objects. The multiple discriminant Fisher analysis with step-by-step inclusion of variables was used as an algorithm of discrimination. The information features were selected on the basis of the subjectively individual approach. The features were selected from frequency areas in which there existed the greatest difference by a reflection coefficient value between spectral reflection coefficients for each kind of plants. The special-purpose literature on these themes was also taken into account. For the analysis of the discrimination efficiency by the classifier of plants (for a different amount of features) a probability of plant proper discrimination was used. A minimum admissible level of the correct detection probability for each kind was set as 90 %. For investigation there were used the real reflection coefficients of plants – maize, bristlegrass and ambrosia that were measured in field conditions.

Root apoplastic transport and water relations cannot account for differences in Cl− transport and Cl−/NO3 − interactions of two grapevine rootstocks differing in salt tolerance

Grapevine is moderately sensitive to salinity and accumulation of toxic levels of Cl− in leaves is the major reason for salt-induced symptoms. In this study, apoplastic Cl− uptake and transport mechanism(s) were investigated in two grapevine (Vitis sp.) rootstock hybrids differing in salt tolerance; 1103 Paulsen (salt tolerant) and K 51–40 (salt sensitive). Increased external salinity caused high Cl− accumulation in shoots of the salt sensitive K 51–40 in comparison to Paulsen. Measurement of 15NO3 − net fluxes under high salinity showed that by increasing external Cl− concentrations K 51–40 roots showed reduced NO3 − accumulation. This was associated with increased accumulation of Cl−. In comparison to Paulsen, K 51–40 showed reduced NO3 −/Cl− root selectivity with increased salinity, but Paulsen had lower selectivity over the whole salinity range (0–45 mM). To examine if root hydraulic and permeability characterisations accounted for differences between varieties, the root pressure probe was used on excised roots. This showed that the osmotic Lpr was significantly smaller than hydrostatic Lpr, but no obvious difference was observed between the rootstocks. The reflection coefficient (σ) values (0.48–0.59) were the same for both rootstocks, and root anatomical studies showed no obvious difference in apoplastic barriers of the main and lateral roots. Comparing the uptake of Cl− with an apoplastic tracer, PTS (3-hydroxy-5,8,10-pyrentrisulphonic acid), showed that there was no correlation between Cl− and PTS transport. These results indicated that bypass flow of salts to the xylem is the same for both rootstocks (0.77 ± 0.2 and 1.05 ± 0.12 %) and hence pointed to differences in membrane transport to explain difference in Cl− transport to the shoot.

Relative peak frequency increment method for quantitative thin-layer thickness estimation

Quantitative thickness estimation of thin-layer is a great challenge in seismic exploration, especially for thin-layer below tuning thickness. In this article, we analyzed the seismic response characteristics of rhythm and gradual type of thin-layer wedge models and presented a new method for thin-layer thickness estimation which uses relative peak frequency increment. This method can describe the peak frequency to thickness relationship of rhythm and gradual thin-layers in unified equation while the traditional methods using amplitude information cannot. What’s more, it won’t be influenced by the absolute value of thin-layer reflection coefficient and peak frequency of wavelet. The unified equations were presented which can be used for rhythm and gradual thin-layer thickness calculation. Model tests showed that the method we introduced has a high precision and it doesn’t need to determine the value of top or bottom reflection coefficient, so it has a more wide application in practice. The application of real data demonstrated that the relative peak frequency increment attribute can character the plane distribution feature and thickness characteristic of channel sand bodies very well.

Effects of voids and rotation on plane waves in generalized thermoelasticity

In the present paper, we study the influence of rotation, thermal and voids parameters on the reflection phenomenon of plane waves in generalized thermoelastic solid with one relaxation time. The governing field equations for isotropic and homogeneous thermoelastic half-space with voids and rotation are formulated in the context of Lord and Shulman theory of generalized thermoelasticity. The solutions of these governing equations indicate the existence of four coupled plane waves, namely; P1; P; P3 and P4 waves in the thermoelastic medium. The boundary conditions at stress-free thermally insulated surface are satisfied to obtain the system of four nonhomogenous equations in the reflection coefficients of various reflected waves for the incidence of P1 wave. A particular material is modeled as the thermoelastic solid half-space to compute the complex absolute values of speeds and reflection coefficients. The speeds and reflection coefficients are shown graphically to observe the influences of rotation, thermal relaxation time and voids parameters.

Scattering of surface water waves involving semi-infinite floating elastic plates on water of finite depth

Two problems of scattering of surface water waves involving a semi-infinite elastic plate and a pair of semi-infinite elastic plates, separated by a gap of finite width, floating horizontally on water of finite depth, are investigated in the present work for a two-dimensional time-harmonic case. Within the frame of linear water wave theory, the solutions of the two boundary value problems under consideration have been represented in the forms of eigenfunction expansions. Approximate values of the reflection and transmission coefficients are obtained by solving an over-determined system of linear algebraic equations in each problem. In both the problems, the method of least squares as well as the singular value decomposition have been employed and tables of numerical values of the reflection and transmission coefficients are presented for specific choices of the parameters for modelling the elastic plates. Our main aim is to check the energy balance relation in each problem which plays a very important role in the present approach of solutions of mixed boundary value problems involving Laplace equations. The main advantage of the present approach of solutions is that the results for the values of reflection and transmission coefficients obtained by using both the methods are found to satisfy the energy-balance relations associated with the respective scattering problems under consideration. The absolute values of the reflection and transmission coefficients are presented graphically against different values of the wave numbers.

Effective Electromagnetic Parameters of Metamaterial Transmission Line Loaded With Asymmetric Unit Cells

In this paper, we propose the generalized extraction procedure for retrieval of the effective constitutive parameters for a metamaterial transmission line loaded with asymmetric unit cells. The asymmetric unit cell is replaced with a transmission line immersed in equivalent bianisotropic medium described by effective parameters e, μ, and Zc, and bianisotropic parameters u and η. The proposed retrieval procedure is applied to novel dual-band unit cells and compared with the standard Nicolson-Ross-Weir (NRW) method that is originally developed for the symmetric unit cell and then extended to the asymmetric one using the averaged value of reflection coefficients. It has been shown that, in case of pronounced asymmetry, the NRW method gives only the exact value of refraction, but effective permittivity and permeability are considerably different from the exact values since they are calculated by means of the approximate value of characteristic impedance.

Propagation Characteristics of Coupled Wave through Micropolar Fluid Interlayer in Micropolar Elastic Solid

Based on micropolar fluid theory and micropolar solid elasticity theory, reflection and transmission characteristics of longitudinal displacement wave and two coupled waves were studied when incident coupled wave propagated through micropolar fluid interlayer in micropolar elastic solid. Using numerical example, the rules of the reflection waves and refraction waves amplitudes varied with incident angle are also discussed. Results show that there exist extremum values of reflection and transmission coefficient for coupled wave. There are two peaks and one zero value of transmission coefficient for longitudinal displacement wave.

Effects of Proteoliposome Composition and Draw Solution Types on Separation Performance of Aquaporin-Based Proteoliposomes: Implications for Seawater Desalination Using Aquaporin-Based Biomimetic Membranes

Aquaporins are a large family of water transport proteins in cell membranes. Their high water permeability and solute rejection make them potential building blocks for high-performance biomimetic membranes for desalination. In the current study, proteoliposomes were prepared using AquaporinZ from Escherichia coli cells, and their separation properties were characterized by stopped-flow measurements. The current study systematically investigated the effect of proteoliposome composition (lipid type, protein-to-lipid ratio (PLR), and the addition of cholesterol) on water permeability and NaCl retention. Among the various lipids investigated, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-based proteoliposomes were found to have excellent osmotic water permeability and NaCl reflection coefficient values. Increasing the PLR of DOPC proteoliposomes up to 1:200 increased their osmotic water permeability. However, further increase in the PLR reduced the osmotic water permeability probably due to the occurrence of defects in the proteoliposomes, whereas the addition of cholesterol improved their osmotic water permeation likely due to defects sealing. The current study also investigated the effect of major dissolved ions in seawater (e.g., Mg(2+) and SO(4)(2-)) on the stability of proteoliposomes, and design criteria for aquaporin-based biomimetic membranes are proposed in the context of desalination.

Circularly Polarized Crossed Dipole on an HIS for 2.4/5.2/5.8-GHz WLAN Applications

A triband circularly polarized (CP) crossed-dipole antenna is introduced for 2.4/5.2/5.8-GHz wireless local area network (WLAN) applications. It employs a single feed and only two crossed trident-shaped dipoles as the primary radiating elements. To achieve a compact radiator size, two techniques are utilized, namely, insertion of a meander-line segment in the middle branch of the tridents and termination of all trident arms with arrowhead-shaped tips. The crossed trident-shaped dipoles are backed by a high impedance surface (HIS) to achieve a broadband characteristic and unidirectional radiation pattern at three bands. The measured impedance bandwidths, based on the -10-dB reflection coefficient values, are 2.21-2.62 GHz (410 MHz), 5.02-5.44 GHz (420 MHz), and 5.62-5.96 GHz (340 MHz), and the measured 3-dB axial-ratio bandwidths are 2.34-2.58 GHz (240 MHz), 5.14-5.38 GHz (240 MHz), and 5.72-5.88 GHz (160 MHz). The proposed antenna exhibits right-hand circular-polarized radiation with high gain.

Feasibility Study of 4G Cellular Antennas for Eyewear Communicating Devices

A feasibility study of 4G cellular antennas operating in the LTE, GSM, DCS, PCS, and WLAN2400 standards for wirelessly connected eyewear is presented. The target bands are 700-960 MHz and 1.7-2.7 GHz. The antenna designs are capacitive coupling element types, with simple layout printed on one side of the printed circuit board (PCB) substrate. Three different antennas are examined in terms of obtainable bandwidth potential, reflection coefficient, and specific absorption rate (SAR) values considering two human-head models (SAM and Visible Human). The best antenna is -6 dB matched and has radiation efficiencies around 14% and 36% in respectively low and high frequency bands. Based on simulation data, SAR values could be above the 1-g standards.

Optimal output mirror reflection coefficient for powerful InGaAs/AlGaAs laser diode arrays

The optimal value of the output mirror reflection coefficient providing the maximum output power under a constant level of electrical power consumption and the maximum external (slope) lasing efficiency for powerful InGaAs/AlGaAs laser diode arrays (LDA) has been estimated experimentally and theoretically. The LDA active layer overheating and amplified spontaneous emission have been taken into account. For advanced LDAs with the thermal resistance of 0.2K/W and the internal optical loss of 0.5cm−1 the optimal output mirror reflection coefficient is equal to 20%. This value is shifted to the high output mirror reflection coefficient side with a decrease of the LDA excitation level, the LDA thermal resistivity and the internal optical loss. It has been shown that the right selection of the output mirror reflection coefficient optimal value provides the LDA operation with 20% excess of the lasing output power and 10% excess of the external lasing efficiency.

Coverage and read range comparison of linearly and circularly polarised radio frequency identification ultra-high frequency tag antennas

This study presents a comparison between two dipoles acting as representatives of ultra-high frequency radio frequency identification (RFID) circularly polarised (CP) and linearly polarised (LP) tag antennas, respectively. As the CP dipole is derived from the LP dipole, they have equivalent reflection coefficient and radiation efficiency values, allowing the comparison to be focused on polarisation and radiation pattern. Then, a comparison of RFID angular and read range is investigated. This is conducted by combining the interrogation of CP and LP tags emulators by CP and LP readers with regulated power. The emulators are made up of the CP and LP dipoles embedded onto RFID tags with analog front-ends. A methodology is described for measuring the maximum angular and read ranges, involving maximum power allowed by European regulation. A 17.9% extra range is achieved by the CP tag and the CP reader compared to the LP tag with any kind of reader. Furthermore, null cancellation is observed in the former case in the region of interest.