Directional statistics-based reflectance model for isotropic bidirectional reflectance distribution functions.

Science.gov (United States)

Nishino, Ko; Lombardi, Stephen

2011-01-01

We introduce a novel parametric bidirectional reflectance distribution function (BRDF) model that can accurately encode a wide variety of real-world isotropic BRDFs with a small number of parameters. The key observation we make is that a BRDF may be viewed as a statistical distribution on a unit hemisphere. We derive a novel directional statistics distribution, which we refer to as the hemispherical exponential power distribution, and model real-world isotropic BRDFs as mixtures of it. We derive a canonical probabilistic method for estimating the parameters, including the number of components, of this novel directional statistics BRDF model. We show that the model captures the full spectrum of real-world isotropic BRDFs with high accuracy, but a small footprint. We also demonstrate the advantages of the novel BRDF model by showing its use for reflection component separation and for exploring the space of isotropic BRDFs.

Bidirectional reflectance distribution function measurements and analysis of retroreflective materials.

Science.gov (United States)

Belcour, Laurent; Pacanowski, Romain; Delahaie, Marion; Laville-Geay, Aude; Eupherte, Laure

2014-12-01

We compare the performance of various analytical retroreflecting bidirectional reflectance distribution function (BRDF) models to assess how they reproduce accurately measured data of retroreflecting materials. We introduce a new parametrization, the back vector parametrization, to analyze retroreflecting data, and we show that this parametrization better preserves the isotropy of data. Furthermore, we update existing BRDF models to improve the representation of retroreflective data.

Investigating Bidirectional Reflectance in the Los Angeles Megacity Using CLARS Multiangle and Hyperspectral Measurements

Science.gov (United States)

Zeng, Z. C.; Natraj, V.; Pongetti, T.; Shia, R. L.; Sander, S. P.; Yung, Y. L.

2017-12-01

The surface reflectance is a key ingredient in the remote sensing of surface and atmospheric properties from space. The determination of atmospheric composition, including greenhouse gas (GHG) and aerosol concentrations, from reflected sunlight requires accurate knowledge of the contribution from the underlying surface. Over megacity areas, such as the Los Angeles (LA) basin, which are major sources of GHGs and anthropogenic aerosols, the quantification of surface reflectance is challenging due to the associated complex land use types. In this study, we investigate the bidirectional reflectance in the Los Angeles megacity area using multiangle and hyperspectral radiance measurements from the California Laboratory for Atmospheric Remote Sensing (CLARS). The CLARS facility is located near the top of Mt. Wilson, at an altitude of 1670 m a.s.l., overlooking the LA megacity area with an FTS operating since 2011 to continuously monitor the GHGs and near-surface aerosols in the basin. The CLARS-FTS offers continuous high-resolution spectral measurements in the visible, near infrared and shortwave infrared spectral regions. The CLARS measurements mimic the off-nadir viewing of a low-Earth orbiting instrument, such as GOSAT and OCO-2, but with daily viewing capability. Eight surface targets with different land use types, including urban parks, industrial and residential areas, are selected in this study. The surface reflectance for specific solar incident and viewing angles is calculated by dividing, for non-absorbing spectral channels on clear days (such that gas and aerosol extinction can be ignored), the observed radiance reflected from surface targets by the observed irradiance. The non-linear Rahman-Pinty-Verstraete (RPV) model is used to model the Bidirectional Reflectance Distribution Function (BRDF) by fitting the multiangle and hyperspectral measurements. By evaluating the retrieved RPV parameters, we find that the RPV model provides a good representation of the

Modelling the bidirectional reflectance distribution functions (BRDF of sea areas polluted by oil

Directory of Open Access Journals (Sweden)

Zbigniew Otremba

2004-12-01

Full Text Available The paper discusses the possibilities of modelling the bi-directional reflectance distribution function (BRDF in sea areas polluted by oil. Three sea basin models are considered: a coastal one free of oil, one polluted by an oil film and one polluted by an oil emulsion. The following concentrations of oil were compared: for the film, 1 cm3 of oil per 1 m2 water surface, for the emulsion 1 cm3 of oil in 1 m3 of water. The optical properties of Romashkino crude oil were taken into consideration, as were various angles of incident solar light. The conversion of BRDFs into a directional distribution of the optical contrast of polluted areas is demonstrated.

Physiochemical, site, and bidirectional reflectance factor characteristics of uniformly moist soils. [Brazil, Spain and the United States of America

Science.gov (United States)

Stoner, E. R.; Baumgardner, M. F. (Principal Investigator)

1980-01-01

The author has identified the following significant results. The bidirectional reflectance factor (0.5 micron to 2.3 micron wavelength interval) and physiochemical properties of over 500 soils from 39 states, Brazil and Spain were measured. Site characteristics of soil temperature regime and moisture zone were used as selection criteria. Parent material and internal drainage were noted for each soil. At least five general types of soil reflectance curves were identified based primarily on the presence or absence of ferric iron absorption bands, organic matter content, and soil drainage characteristics. Reflectance in 10 bands across the spectrum was found to be negatively correlated with the natural log of organic matter content.

Bidirectional Thermo-Mechanical Properties of Foam Core Materials Using DIC

DEFF Research Database (Denmark)

Taher, Siavash Talebi; Thomsen, Ole Thybo; M Dulieu-Barton, Janice

2011-01-01

mechanical properties at room and at elevated temperatures. The MAF enables the realization of pure compression or high compression to shear bidirectional loading conditions that is not possible with conventional Arcan fixtures. The MAF is attached to a standard universal test machine equiped...... with an environmental chamber using specially designed grips that allow the specimen to rotate, and hence reduces paristic effects due to misalignment. The objective is to measure the unidirectional and bidirectional mechanical properties of PVC foam materials at elevated tempreature using digital image correlation...

Bidirectional reflectance distribution function of Spectralon white reflectance standard illuminated by incoherent unpolarized and plane-polarized light.

Science.gov (United States)

Bhandari, Anak; Hamre, Børge; Frette, Øvynd; Zhao, Lu; Stamnes, Jakob J; Kildemo, Morten

2011-06-01

A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence. Our measurements show deviations of the BRDF for the Spectralon white reflectance standard from that of a Lambertian reflector that depend both on the angle of incidence and the polarization states of the incident light and detected light. The non-Lambertian reflection characteristics were found to increase more toward the direction of specular reflection as the angle of incidence gets larger.

Far-infrared /FIR/ optical black bidirectional reflectance distribution function /BRDF/

Science.gov (United States)

Smith, S. M.

1981-01-01

A nonspecular reflectometer and its operation at far-infrared wavelengths are described. Large differences in nonspecular reflectance were found to exist between different optically black coatings. Normal incidence bidirectional reflectance distribution function /BRDF) measurements at wavelengths between 12 and 316 microns of three black coatings show that their mean BRDFs increase with wavelength. The specularity of two of these coatings also showed a strong wavelength dependence, while the specularity of one coating seemed independent of wavelength. The BRDF of one coating depended on the angle of incidence at 12 and 38 microns, but not at 316 microns. Beyond 200 microns, it was found necessary to correct the measurements for the beam spread of the instrument.

Bidirectional reflectance effects derived from ASAS imagery of a pecan orchard

Science.gov (United States)

Staenz, Karl; Gauthier, Robert P.; Teillet, Phil M.; Williams, Daniel J.

1993-09-01

Bidirectional reflectance factors (BRF) for a pecan orchard have been studied using Advanced Solid-State Array Spectrometer (ASAS) data acquired in the solar principal plane at altitudes of 2300 m and 5300 m above ground. In particular, the angular dependency of the BRF of different targets such as sunlit and shaded portions of the pecan tree, orchard floor, and soil (road) have been studied for viewing directions between -45 degrees and +45 degrees. The results indicate in general an increasing reflectance from the forward scattering direction to the backscattering direction. In addition, an increase in pixel size has significant effects on the surface BRFs.

An efficient strategy for the inversion of bidirectional reflectance models with satellite remote sensing data

Energy Technology Data Exchange (ETDEWEB)

Privette, J.L.

1994-12-31

The angular distribution of radiation scattered by the earth surface contains information on the structural and optical properties of the surface. Potentially, this information may be retrieved through the inversion of surface bidirectional reflectance distribution function (BRDF) models. This report details the limitations and efficient application of BRDF model inversions using data from ground- and satellite-based sensors. A turbid medium BRDF model, based on the discrete ordinates solution to the transport equation, was used to quantify the sensitivity of top-of-canopy reflectance to vegetation and soil parameters. Results were used to define parameter sets for inversions. Using synthetic reflectance values, the invertibility of the model was investigated for different optimization algorithms, surface and sampling conditions. Inversions were also conducted with field data from a ground-based radiometer. First, a soil BRDF model was inverted for different soil and sampling conditions. A condition-invariant solution was determined and used as the lower boundary condition in canopy model inversions. Finally, a scheme was developed to improve the speed and accuracy of inversions.

Analysis of snow bidirectional reflectance from ARCTAS Spring-2008 Campaign

Directory of Open Access Journals (Sweden)

A. Lyapustin

2010-05-01

Full Text Available The spring 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS experiment was one of major intensive field campaigns of the International Polar Year aimed at detailed characterization of atmospheric physical and chemical processes in the Arctic region. A part of this campaign was a unique snow bidirectional reflectance experiment on the NASA P-3B aircraft conducted on 7 and 15 April by the Cloud Absorption Radiometer (CAR jointly with airborne Ames Airborne Tracking Sunphotometer (AATS and ground-based Aerosol Robotic Network (AERONET sunphotometers. The CAR data were atmospherically corrected to derive snow bidirectional reflectance at high 1° angular resolution in view zenith and azimuthal angles along with surface albedo. The derived albedo was generally in good agreement with ground albedo measurements collected on 15 April. The CAR snow bidirectional reflectance factor (BRF was used to study the accuracy of analytical Ross-Thick Li-Sparse (RTLS, Modified Rahman-Pinty-Verstraete (MRPV and Asymptotic Analytical Radiative Transfer (AART BRF models. Except for the glint region (azimuthal angles φ<40°, the best fit MRPV and RTLS models fit snow BRF to within ±0.05. The plane-parallel radiative transfer (PPRT solution was also analyzed with the models of spheres, spheroids, randomly oriented fractal crystals, and with a synthetic phase function. The latter merged the model of spheroids for the forward scattering angles with the fractal model in the backscattering direction. The PPRT solution with synthetic phase function provided the best fit to measured BRF in the full range of angles. Regardless of the snow grain shape, the PPRT model significantly over-/underestimated snow BRF in the glint/backscattering regions, respectively, which agrees with other studies. To improve agreement with experiment, we introduced a model of macroscopic snow surface roughness by averaging the PPRT solution over the

Analysis of Snow Bidirectional Reflectance from ARCTAS Spring-2008 Campaign

Science.gov (United States)

Lyapustin, A.; Gatebe, C. K.; Redemann, J.; Kahn, R.; Brandt, R.; Russell, P.; King, M. D.; Pedersen, C. A.; Gerland, S.; Poudyal, R.;

Laboratory-based bidirectional reflectance distribution functions of radiometric tarps

International Nuclear Information System (INIS)

Georgiev, Georgi T.; Butler, James J.

2008-01-01

Laboratory-based bidirectional reflectance distribution functions (BRDFs) of radiometric tarp samples used in the vicarious calibration of Earth remote sensing satellite instruments are presented in this paper. The results illustrate the BRDF dependence on the orientation of the tarps' weft and warp threads. The study was performed using the GSFC scatterometer at incident zenith angles of 0 deg., 10 deg., and 30 deg.; scatter zenith angles from 0 deg. to 60 deg.; and scatter azimuth angles of 0 deg., 45 deg., 90 deg., 135 deg., and 180 deg.. The wavelengths were 485 nm, 550 nm, 633 nm, and 800 nm. The tarp's weft and warp dependence on BRDF is well defined at all measurement geometries and wavelengths. The BRDF difference can be as high as 8% at 0 deg. incident angle and 12% at 30 deg. incident angle. The fitted BRDF data show a very small discrepancy from the measured ones. New data on the forward and backscatter properties of radiometric tarps are reported. The backward scatter is well pronounced for the white samples. The black sample has well-pronounced forward scatter. The provided BRDF characterization of radiometric tarps is an excellent reference for anyone interested in using tarps for radiometric calibrations. The results are NIST traceable

Laboratory-based bidirectional reflectance distribution functions of radiometric tarps.

Science.gov (United States)

Georgiev, Georgi T; Butler, James J

2008-06-20

Laboratory-based bidirectional reflectance distribution functions (BRDFs) of radiometric tarp samples used in the vicarious calibration of Earth remote sensing satellite instruments are presented in this paper. The results illustrate the BRDF dependence on the orientation of the tarps' weft and warp threads. The study was performed using the GSFC scatterometer at incident zenith angles of 0 degrees, 10 degrees, and 30 degrees; scatter zenith angles from 0 degrees to 60 degrees; and scatter azimuth angles of 0 degrees, 45 degrees, 90 degrees, 135 degrees, and 180 degrees. The wavelengths were 485 nm, 550 nm, 633 nm, and 800 nm. The tarp's weft and warp dependence on BRDF is well defined at all measurement geometries and wavelengths. The BRDF difference can be as high as 8% at 0 degrees incident angle and 12% at 30 degrees incident angle. The fitted BRDF data show a very small discrepancy from the measured ones. New data on the forward and backscatter properties of radiometric tarps are reported. The backward scatter is well pronounced for the white samples. The black sample has well-pronounced forward scatter. The provided BRDF characterization of radiometric tarps is an excellent reference for anyone interested in using tarps for radiometric calibrations. The results are NIST traceable.

Canopy bidirectional reflectance calculation based on Adding method and SAIL formalism: AddingS / AddingSD

NARCIS (Netherlands)

Kallel, A.; Verhoef, W.; Hegarat-Mascle, Le S.; Ottle, C.; Hubert-Moy, L.

2008-01-01

The SAIL model (proposed by Verhoef) is largely used in the remote sensing community to calculate the canopy Bidirectional Reflectance Distribution Function. The simulation results appear acceptable compared to observations especially for not very dense planophile vegetation. However, for

Modeling Bidirectional Reflectance Distribution Function of One-dimensional Random Rough Surfaces with the Finite Difference Time Domain Method

Directory of Open Access Journals (Sweden)

Min-Jhong Gu

2014-08-01

Full Text Available This article describes the development of a suite of programs that is capable of simulating the radiation properties of a random rough surface (RRS. The fundamental approach involves the generation, by fast Fourier transform (FFT built with rigorous finite difference time domain (FDTD, as the theoretical basis for the simulation of a bidirectional reflectance distribution function (BRDF of the RRS. The results are compared with the measurements and modeling of existing work to verify the feasibility of customized programming. It was found that the results of this study were a better match to the measurement data than those achieved in other modeling work.

A geometrical optics polarimetric bidirectional reflectance distribution function for dielectric and metallic surfaces.

Science.gov (United States)

Hyde, M W; Schmidt, J D; Havrilla, M J

2009-11-23

A polarimetric bidirectional reflectance distribution function (pBRDF), based on geometrical optics, is presented. The pBRDF incorporates a visibility (shadowing/masking) function and a Lambertian (diffuse) component which distinguishes it from other geometrical optics pBRDFs in literature. It is shown that these additions keep the pBRDF bounded (and thus a more realistic physical model) as the angle of incidence or observation approaches grazing and better able to model the behavior of light scattered from rough, reflective surfaces. In this paper, the theoretical development of the pBRDF is shown and discussed. Simulation results of a rough, perfect reflecting surface obtained using an exact, electromagnetic solution and experimental Mueller matrix results of two, rough metallic samples are presented to validate the pBRDF.

MECHANICAL AND THERMO–MECHANICAL PROPERTIES OF BI-DIRECTIONAL AND SHORT CARBON FIBER REINFORCED EPOXY COMPOSITES

Directory of Open Access Journals (Sweden)

G. AGARWAL

2014-10-01

Full Text Available This paper based on bidirectional and short carbon fiber reinforced epoxy composites reports the effect of fiber loading on physical, mechanical and thermo-mechanical properties respectively. The five different fiber loading, i.e., 10wt. %, 20wt. %, 30wt. %, 40wt. % and 50wt. % were taken for evaluating the above said properties. The physical and mechanical properties, i.e., hardness, tensile strength, flexural strength, inter-laminar shear strength and impact strength are determined to represent the behaviour of composite structures with that of fiber loading. Thermo-mechanical properties of the material are measured with the help of Dynamic Mechanical Analyser to measure the damping capacity of the material that is used to reduce the vibrations. The effect of storage modulus, loss modulus and tan delta with temperature are determined. Finally, Cole–Cole analysis is performed on both bidirectional and short carbon fiber reinforced epoxy composites to distinguish the material properties of either homogeneous or heterogeneous materials. The results show that with the increase in fiber loading the mechanical properties of bidirectional carbon fiber reinforced epoxy composites increases as compared to short carbon fiber reinforced epoxy composites except in case of hardness, short carbon fiber reinforced composites shows better results. Similarly, as far as Loss modulus, storage modulus is concerned bidirectional carbon fiber shows better damping behaviour than short carbon fiber reinforced composites.

Far-ultraviolet Bidirectional Photometry of Apollo Soil 10084: New Results from The Southwest Ultraviolet Reflectance Chamber (SwURC).

Science.gov (United States)

Raut, U.

2017-12-01

We report new measurements of the far-ultraviolet (115-180 nm) bidirectional reflectance of Apollo soil 10084 in the Southwest Ultraviolet Reflectance Chamber (SwURC). We find the bidirectional reflectance distribution function (BRDF) to be featureless in this wavelength region, though with a small blue slope. The angular distribution of the BRDF at Ly-α and 160 nm shows that this mature mare soil, containing nanophase Fe and enriched in Ti, anisotropically scatters light in the forward direction. The phase angle dependence of the BRDF is fitted with Hapke's photometric model with an additional diffuse-directional term. Future plans include measurements of mare and highland soils of differing maturity index (Is/FeO), water ice frost and lunar soil-ice aggregates. Such measurements will help constrain the abundance and distribution of the water ice on the illuminated lunar surface and dark permanently shadowed regions of the moon, as reported by LRO-LAMP.

Evaluation of complex gonioapparent samples using a bidirectional spectrometer.

Science.gov (United States)

Rogelj, Nina; Penttinen, Niko; Gunde, Marta Klanjšek

2015-08-24

Many applications use gonioapparent targets whose appearance depends on irradiation and viewing angles; the strongest effects are provided by light diffraction. These targets, optically variable devices (OVDs), are used in both security and authentication applications. This study introduces a bidirectional spectrometer, which enables to analyze samples with most complex angular and spectral properties. In our work, the spectrometer is evaluated with samples having very different types of reflection, concerning spectral and angular distributions. Furthermore, an OVD containing several different grating patches is evaluated. The device uses automatically adjusting exposure time to provide maximum signal dynamics and is capable of doing steps as small as 0.01°. However, even 2° steps for the detector movement showed that this device is more than capable of characterizing even the most complex reflecting surfaces. This study presents sRGB visualizations, discussion of bidirectional reflection, and accurate grating period calculations for all of the grating samples used.

Calculating the bidirectional reflectance of natural vegetation covers using Boolean models and geometric optics

Science.gov (United States)

Strahler, Alan H.; Li, Xiao-Wen; Jupp, David L. B.

1991-01-01

The bidirectional radiance or reflectance of a forest or woodland can be modeled using principles of geometric optics and Boolean models for random sets in a three dimensional space. This model may be defined at two levels, the scene includes four components; sunlight and shadowed canopy, and sunlit and shadowed background. The reflectance of the scene is modeled as the sum of the reflectances of the individual components as weighted by their areal proportions in the field of view. At the leaf level, the canopy envelope is an assemblage of leaves, and thus the reflectance is a function of the areal proportions of sunlit and shadowed leaf, and sunlit and shadowed background. Because the proportions of scene components are dependent upon the directions of irradiance and exitance, the model accounts for the hotspot that is well known in leaf and tree canopies.

Modeling bidirectional reflectance of forests and woodlands using Boolean models and geometric optics

Science.gov (United States)

Strahler, Alan H.; Jupp, David L. B.

1990-01-01

Geometric-optical discrete-element mathematical models for forest canopies have been developed using the Boolean logic and models of Serra. The geometric-optical approach is considered to be particularly well suited to describing the bidirectional reflectance of forest woodland canopies, where the concentration of leaf material within crowns and the resulting between-tree gaps make plane-parallel, radiative-transfer models inappropriate. The approach leads to invertible formulations, in which the spatial and directional variance provides the means for remote estimation of tree crown size, shape, and total cover from remotedly sensed imagery.

Bidirectional optical scattering facility

Data.gov (United States)

Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...

Experimental analysis of bidirectional reflectance distribution function cross section conversion term in direction cosine space.

Science.gov (United States)

Butler, Samuel D; Nauyoks, Stephen E; Marciniak, Michael A

2015-06-01

Of the many classes of bidirectional reflectance distribution function (BRDF) models, two popular classes of models are the microfacet model and the linear systems diffraction model. The microfacet model has the benefit of speed and simplicity, as it uses geometric optics approximations, while linear systems theory uses a diffraction approach to compute the BRDF, at the expense of greater computational complexity. In this Letter, nongrazing BRDF measurements of rough and polished surface-reflecting materials at multiple incident angles are scaled by the microfacet cross section conversion term, but in the linear systems direction cosine space, resulting in great alignment of BRDF data at various incident angles in this space. This results in a predictive BRDF model for surface-reflecting materials at nongrazing angles, while avoiding some of the computational complexities in the linear systems diffraction model.

[The research on bidirectional reflectance computer simulation of forest canopy at pixel scale].

Science.gov (United States)

Song, Jin-Ling; Wang, Jin-Di; Shuai, Yan-Min; Xiao, Zhi-Qiang

2009-08-01

Computer simulation is based on computer graphics to generate the realistic 3D structure scene of vegetation, and to simulate the canopy regime using radiosity method. In the present paper, the authors expand the computer simulation model to simulate forest canopy bidirectional reflectance at pixel scale. But usually, the trees are complex structures, which are tall and have many branches. So there is almost a need for hundreds of thousands or even millions of facets to built up the realistic structure scene for the forest It is difficult for the radiosity method to compute so many facets. In order to make the radiosity method to simulate the forest scene at pixel scale, in the authors' research, the authors proposed one idea to simplify the structure of forest crowns, and abstract the crowns to ellipsoids. And based on the optical characteristics of the tree component and the characteristics of the internal energy transmission of photon in real crown, the authors valued the optical characteristics of ellipsoid surface facets. In the computer simulation of the forest, with the idea of geometrical optics model, the gap model is considered to get the forest canopy bidirectional reflectance at pixel scale. Comparing the computer simulation results with the GOMS model, and Multi-angle Imaging SpectroRadiometer (MISR) multi-angle remote sensing data, the simulation results are in agreement with the GOMS simulation result and MISR BRF. But there are also some problems to be solved. So the authors can conclude that the study has important value for the application of multi-angle remote sensing and the inversion of vegetation canopy structure parameters.

Measurement and application of bidirectional reflectance distribution function

Science.gov (United States)

Liao, Fei; Li, Lin; Lu, Chengwen

2016-10-01

When a beam of light with certain intensity and distribution reaches the surface of a material, the distribution of the diffused light is related to the incident angle, the receiving angle, the wavelength of the light and the types of the material. Bidirectional Reflectance Distribution Function (BRDF) is a method to describe this distribution. For an optical system, the optical and mechanical materials' BRDF are unique, and if we want to calculate stray light of the system we should know the correct BRDF data of the whole materials. There are fundamental significances in the area of space remote sensor where BRDF is needed in the precise radiation calibration. It is also important in the military field where BRDF can be used in the object identification and target tracking, etc. In this paper, 11 kinds of aerospace materials' BRDF are measured and more than 310,000 groups of BRDF data are achieved , and also a BRDF database is established in China for the first time. With the BRDF data of the database, we can create the detector model, build the stray light radiation surface model in the stray light analysis software. In this way, the stray radiation on the detector can be calculated correctly.

The importance of leaf BRDF in forest canopy bidirectional reflectance : a case study using simulated canopy architecture and PBRT ray tracing

NARCIS (Netherlands)

Biliourios, D.; Van der Zande, D.; Verstraeten, W.W.; Stuckens, J.; Muys, B.; Dutre, Ph.; Coppin, P.

2013-01-01

Two Fagus sylvatica L. stands with different Leaf Area Index and similar planophile Leaf Angle Distribution were created with L-systems based plant growth software and rendered using both Lambertian and Bousquet’s model leaf Bidirectional Reflectance Distribution Function (BRDF) assumption. During

Acquisition of Bidirectional Reflectance Factor Dataset Using a Micro Unmanned Aerial Vehicle and a Consumer Camera

Directory of Open Access Journals (Sweden)

Jouni I. Peltoniemi

2010-03-01

Full Text Available This paper describes a method for retrieving the bidirectional reflectance factor (BRF of land-surface areas, using a small consumer camera on board an unmanned aerial vehicle (UAV and introducing an advanced calibration routine. Images with varying view directions were taken of snow cover using the UAV. The vignetting effect was corrected from the images, and reflectance factor images were calculated using a calibrated white target as a reference. After spatial registration of the images using a corresponding point method, the target surface was divided into a grid, and a BRF was generated for each grid element. Lastly a model was fitted to the BRF dataset for data interpretation. The retrieved BRF were compared to parallel ground measurements. Comparison showed similar BRF and reflectance factor characteristics, which suggests that accurate measurements can be taken with cheap consumer cameras, if enough attention is paid to calibration of the images.

Observing System Simulations for Small Satellite Formations Estimating Bidirectional Reflectance

Science.gov (United States)

Nag, Sreeja; Gatebe, Charles K.; de Weck, Olivier

2015-01-01

The bidirectional reflectance distribution function (BRDF) gives the reflectance of a target as a function of illumination geometry and viewing geometry, hence carries information about the anisotropy of the surface. BRDF is needed in remote sensing for the correction of view and illumination angle effects (for example in image standardization and mosaicing), for deriving albedo, for land cover classification, for cloud detection, for atmospheric correction, and other applications. However, current spaceborne instruments provide sparse angular sampling of BRDF and airborne instruments are limited in the spatial and temporal coverage. To fill the gaps in angular coverage within spatial, spectral and temporal requirements, we propose a new measurement technique: Use of small satellites in formation flight, each satellite with a VNIR (visible and near infrared) imaging spectrometer, to make multi-spectral, near-simultaneous measurements of every ground spot in the swath at multiple angles. This paper describes an observing system simulation experiment (OSSE) to evaluate the proposed concept and select the optimal formation architecture that minimizes BRDF uncertainties. The variables of the OSSE are identified; number of satellites, measurement spread in the view zenith and relative azimuth with respect to solar plane, solar zenith angle, BRDF models and wavelength of reflection. Analyzing the sensitivity of BRDF estimation errors to the variables allow simplification of the OSSE, to enable its use to rapidly evaluate formation architectures. A 6-satellite formation is shown to produce lower BRDF estimation errors, purely in terms of angular sampling as evaluated by the OSSE, than a single spacecraft with 9 forward-aft sensors. We demonstrate the ability to use OSSEs to design small satellite formations as complements to flagship mission data. The formations can fill angular sampling gaps and enable better BRDF products than currently possible.

Observing system simulations for small satellite formations estimating bidirectional reflectance

Science.gov (United States)

Nag, Sreeja; Gatebe, Charles K.; Weck, Olivier de

2015-12-01

The bidirectional reflectance distribution function (BRDF) gives the reflectance of a target as a function of illumination geometry and viewing geometry, hence carries information about the anisotropy of the surface. BRDF is needed in remote sensing for the correction of view and illumination angle effects (for example in image standardization and mosaicing), for deriving albedo, for land cover classification, for cloud detection, for atmospheric correction, and other applications. However, current spaceborne instruments provide sparse angular sampling of BRDF and airborne instruments are limited in the spatial and temporal coverage. To fill the gaps in angular coverage within spatial, spectral and temporal requirements, we propose a new measurement technique: use of small satellites in formation flight, each satellite with a VNIR (visible and near infrared) imaging spectrometer, to make multi-spectral, near-simultaneous measurements of every ground spot in the swath at multiple angles. This paper describes an observing system simulation experiment (OSSE) to evaluate the proposed concept and select the optimal formation architecture that minimizes BRDF uncertainties. The variables of the OSSE are identified; number of satellites, measurement spread in the view zenith and relative azimuth with respect to solar plane, solar zenith angle, BRDF models and wavelength of reflection. Analyzing the sensitivity of BRDF estimation errors to the variables allow simplification of the OSSE, to enable its use to rapidly evaluate formation architectures. A 6-satellite formation is shown to produce lower BRDF estimation errors, purely in terms of angular sampling as evaluated by the OSSE, than a single spacecraft with 9 forward-aft sensors. We demonstrate the ability to use OSSEs to design small satellite formations as complements to flagship mission data. The formations can fill angular sampling gaps and enable better BRDF products than currently possible.

Goniophotometry and assessment of bidirectional photometric properties of complex fenestration systems

Energy Technology Data Exchange (ETDEWEB)

Andersen, M. [Building Technology Programme, Department of Architecture, Massachusetts Institute of Technology, Cambridge, MA (United States); Boer, J. de [Fraunhofer Institute for Building Physics, Stuttgart (Germany)

2006-07-01

This paper seeks to provide an overview of the currently available assessment tools for bidirectional transmission or reflection distribution functions (BTDFs and BRDFs) of complex fenestration systems (CFS). In the first part of the paper, the existing experimental devices (goniophotometers) developed specifically for CFS measurement are described. All but two are based on a scanning process to investigate the emerging light flux distribution, the alternative approach being based on digital imaging techniques. A critical analysis of their advantages and shortcomings is proposed to provide both researchers interested in replicating them and more generally potential users of BTDF or BRDF data with a lucid idea of the available options. The second part presents an alternative to physical measurements, made possible by using computer simulations based on ray-tracing techniques. In this case, every component of the modelled system must be of well-known geometric and material properties. Two virtual goniophotometer models are described and their validation results are analyzed. Whether they have been generated experimentally or through simulation, BTDF and BRDF data need to be processed into transmission or reflection functions that are directly related to sky and room conditions for them to be usable. The third part of the paper introduces a new BT(R)DF database management system whose aim is to become a reference resource for viewing and interpreting these complex data. The main visualization features of its interface are presented, that include a special focus on flexibility and on providing intuitive graphical information, in a similar way as for luminaires selection in electric lighting design. (author)

Hybrid artificial bee colony algorithm for parameter optimization of five-parameter bidirectional reflectance distribution function model.

Science.gov (United States)

Wang, Qianqian; Zhao, Jing; Gong, Yong; Hao, Qun; Peng, Zhong

2017-11-20

A hybrid artificial bee colony (ABC) algorithm inspired by the best-so-far solution and bacterial chemotaxis was introduced to optimize the parameters of the five-parameter bidirectional reflectance distribution function (BRDF) model. To verify the performance of the hybrid ABC algorithm, we measured BRDF of three kinds of samples and simulated the undetermined parameters of the five-parameter BRDF model using the hybrid ABC algorithm and the genetic algorithm, respectively. The experimental results demonstrate that the hybrid ABC algorithm outperforms the genetic algorithm in convergence speed, accuracy, and time efficiency under the same conditions.

High-accuracy measurements of snow Bidirectional Reflectance Distribution Function at visible and NIR wavelengths – comparison with modelling results

Directory of Open Access Journals (Sweden)

M. Dumont

2010-03-01

Full Text Available High-accuracy measurements of snow Bidirectional Reflectance Distribution Function (BRDF were performed for four natural snow samples with a spectrogonio-radiometer in the 500–2600 nm wavelength range. These measurements are one of the first sets of direct snow BRDF values over a wide range of lighting and viewing geometry. They were compared to BRDF calculated with two optical models. Variations of the snow anisotropy factor with lighting geometry, wavelength and snow physical properties were investigated. Results show that at wavelengths with small penetration depth, scattering mainly occurs in the very top layers and the anisotropy factor is controlled by the phase function. In this condition, forward scattering peak or double scattering peak is observed. In contrast at shorter wavelengths, the penetration of the radiation is much deeper and the number of scattering events increases. The anisotropy factor is thus nearly constant and decreases at grazing observation angles. The whole dataset is available on demand from the corresponding author.

Comparison of ultraviolet Bi-directional Reflectance Distribution Function (BRDF) measurements of diffusers used in the calibration of the Total Ozone Mapping Spectrometer (TOMS)

NARCIS (Netherlands)

Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.

2002-01-01

The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those

Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

Science.gov (United States)

Zhan, Hanyu; Voelz, David G.

2016-12-01

The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.

Data sets for modeling: A retrospective collection of Bidirectional Reflectance and Forest Ecosystems Dynamics Multisensor Aircraft Campaign data sets

Energy Technology Data Exchange (ETDEWEB)

Walthall, C.L.; Kim, M. (Univ. of Maryland, College Park, MD (United States). Dept. of Geography); Williams, D.L.; Meeson, B.W.; Agbu, P.A.; Newcomer, J.A.; Levine, E.R.

1993-12-01

The Biospheric Sciences Branch, within the Laboratory for Terrestrial Physics at NASA's Goddard Space Flight Center, has assembled two data sets for free dissemination to the remote sensing research community. One data set, referred to as the Retrospective Bidirectional Reflectance Distribution Function (BRDF) Data Collection, is a collection of bidirectional reflectance and supporting biophysical measurements of surfaces ranging in diversity from bare soil to heavily forested canopies. The other data collection, resulting from measurements made in association with the Forest Ecosystems Dynamic Multisensor Aircraft Campaign (FED MAC), contains data that are relevant to ecosystem process models, particularly those which have been modified to incorporate remotely sensed data. Both of these collections are being made available to the science community at large in order to facilitate model development, validation, and usage. These data collections are subsets which have been compiled and consolidated from individual researcher or from several large data set collections including: the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE); FED MAC; the Superior National Forest Project (SNF); the Geologic Remote Sensing Field Experiment (GRSFE); and Agricultural Inventories through Space Applications of Remote Sensing (AgriStars). The complete, stand-along FED MAC Data Collection contains atmospheric, vegetation, and soils data acquired during field measurement campaigns conducted at international Papers' Northern Experimental Forest located approximately 40 km north of Bangor, Maine. Reflectance measurements at the canopy, branch, and needle level are available, along with the detailed canopy architectural measurements.

Bidirectional Radio-Over-Fiber System With Phase-Modulation Downlink and RF Oscillator-Free Uplink Using a Reflective SOA

DEFF Research Database (Denmark)

Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

2008-01-01

We propose and demonstrate a bidirectional radio-over-fiber (RoF) system based on a reflective semiconductor optical amplifier (RSOA). In this system, phase-modulated 5.25-GHz radio frequency (RF) carrying 850 Mb/s is used for the downstream signal. Optical envelope detection of 10-GHz RF carryin......-effective. The experimental results indicate that after simultaneous transmission of downstream and upstream signals over 25-km fiber, the receiver sensitivities are -22 and -14.5 dBm, respectively....

Coupled Retrieval of Aerosol Properties and Surface Reflection Using the Airborne Multi-angle SpectroPolarimetric Imager (AirMSPI)

Science.gov (United States)

Xu, F.; van Harten, G.; Kalashnikova, O. V.; Diner, D. J.; Seidel, F. C.; Garay, M. J.; Dubovik, O.

2016-12-01

The Airborne Multi-angle SpectroPolarimetric Imager (AirMSPI) [1] has been flying aboard the NASA ER-2 high altitude aircraft since October 2010. In step-and-stare operation mode, AirMSPI acquires radiance and polarization data at 355, 380, 445, 470*, 555, 660*, 865*, and 935 nm (* denotes polarimetric bands). The imaged area covers about 10 km by 10 km and is observed from 9 view angles between ±67° off of nadir. We have developed an efficient and flexible code that uses the information content of AirMSPI data for a coupled retrieval of aerosol properties and surface reflection. The retrieval was built based on the multi-pixel optimization concept [2], with the use of a hybrid radiative transfer model [3] that combines the Markov Chain [4] and adding/doubling methods [5]. The convergence and robustness of our algorithm is ensured by applying constraints on (a) the spectral variation of the Bidirectional Polarization Distribution Function (BPDF) and angular shape of the Bidirectional Reflectance Distribution Function (BRDF); (b) the spectral variation of aerosol optical properties; and (c) the spatial variation of aerosol parameters across neighboring image pixels. Our retrieval approach has been tested using over 20 AirMSPI datasets having low to moderately high aerosol loadings ( 0.02550-nmSpace Sci. Rev. 16, 527 (1974).

Roughness-reflectance relationship of bare desert terrain: An empirical study

International Nuclear Information System (INIS)

Shoshany, M.

1993-01-01

A study of the bidirectional reflectance distribution function (BRDF) in relation to surface roughness properties was conducted in arid land near Fowlers Gap Research Station, New South Wales, Australia. Such empirical study is necessary for investigating the possibility of determining terrain geomorphological parameters from bidirectional reflectance data. A new apparatus was developed to take accurate hemispherical directions radiance measurements (HDRM). A digitizer for three-dimensional in situ roughness measurements was also developed. More than 70 hemispherical data sets were collected for various illumination conditions and surface types of desert stony pavements and rocky terrain slopes. In general, it was found that most of the surfaces exhibited an anisotropic reflection, combining a major component of backscattering. The BRDF of different surface types in relation to their roughness properties as determined by the field digitizer were then examined. Results showed that sites that are considered to differ significantly from a geomorphological point of view would not necessarily form a different BRDF

Infrared reflection properties and modelling of in situ reflection measurements on plasma-facing materials in Tore Supra

International Nuclear Information System (INIS)

Reichle, R; Desgranges, C; Faisse, F; Pocheau, C; Lasserre, J-P; Oelhoffen, F; Eupherte, L; Todeschini, M

2009-01-01

Tore Supra has-like ITER-reflecting internal surfaces, which can perturb the machine protection systems based on infrared (IR) thermography. To ameliorate this situation, we have measured and modelled in the 3-5 μm wavelength range the bi-directional reflection distribution function (BRDF) of wall material samples from Tore Supra and conducted in situ reflection measurements and simulated them with the CEA COSMOS code. BRDF results are presented for B 4 C and carbon fibre composite (CFC) tiles. The hemispherical integrated reflection ranges from 0.12 for the B 4 C sample to 0.39 for a CFC tile from the limiter erosion zone. In situ measurements of the IR reflection of a blackbody source off an ICRH and an LHCD antenna of Tore Supra are well reproduced by the simulation.

Infrared reflection properties and modelling of in situ reflection measurements on plasma-facing materials in Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Reichle, R; Desgranges, C; Faisse, F; Pocheau, C [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Lasserre, J-P; Oelhoffen, F; Eupherte, L; Todeschini, M [CEA, DAM, CESTA, F-33114 Le Barp (France)

2009-12-15

Tore Supra has-like ITER-reflecting internal surfaces, which can perturb the machine protection systems based on infrared (IR) thermography. To ameliorate this situation, we have measured and modelled in the 3-5 {mu}m wavelength range the bi-directional reflection distribution function (BRDF) of wall material samples from Tore Supra and conducted in situ reflection measurements and simulated them with the CEA COSMOS code. BRDF results are presented for B{sub 4}C and carbon fibre composite (CFC) tiles. The hemispherical integrated reflection ranges from 0.12 for the B{sub 4}C sample to 0.39 for a CFC tile from the limiter erosion zone. In situ measurements of the IR reflection of a blackbody source off an ICRH and an LHCD antenna of Tore Supra are well reproduced by the simulation.

Bidirectional reflectance and VIS-NIR spectroscopy of cometary analogues under simulated space conditions

Science.gov (United States)

Jost, Bernhard; Pommerol, Antoine; Poch, Olivier; Yoldi, Zuriñe; Fornasier, Sonia; Hasselmann, Pedro Henrique; Feller, Clément; Carrasco, Nathalie; Szopa, Cyril; Thomas, Nicolas

2017-10-01

This work is intended to be the second publication in a series of papers reporting on the spectro-photometric properties of cometary analogues measured in the laboratory. Herein, we provide in-situ hyperspectral imaging data in the 0.40-2.35 μm range from three sublimation experiments under simulated space conditions in thermal vacuum from samples made of water ice, carbonaceous compounds and complex organic molecules. The dataset is complemented by measurements of the bidirectional reflectance in the visible (750 nm) spectral range before and after sublimation. A qualitative characterization of surface evolution processes is provided as well as a description of morphological changes during the simulation experiment. The aim of these experiments is to mimic the spectrum of comet 67P/Churyumov-Gerasimenko (67P) as acquired by the Rosetta mission by applying sublimation experiments on the mixtures of water ice with a complex organic material (tholins) and carbonaceous compounds (carbon black; activated charcoal) studied in our companion publication (Jost et al., submitted). Sublimation experiments are needed to develop the particular texture (high porosity), expected on the nucleus' surface, which might have a strong influence on spectro-photometric properties. The spectrally best matching mixtures of non volatile organic molecules from Jost et al. (submitted) are mixed with fine grained water ice particles and evolved in a thermal vacuum chamber, in order to monitor the influence of the sublimation process on their spectro-photometric properties. We demonstrate that the way the water ice and the non-volatile constituents are mixed, plays a major role in the formation and evolution of a surface residue mantle as well as having influence on the consolidation processes of the underlying ice. Additionally it results in different activity patterns under simulated insolation cycles. Further we show that the phase curves of samples having a porous surface mantle layer

Bidirectional reflectance distribution function modeling of one-dimensional rough surface in the microwave band

International Nuclear Information System (INIS)

Guo Li-Xin; Gou Xue-Yin; Zhang Lian-Bo

2014-01-01

In this study, the bidirectional reflectance distribution function (BRDF) of a one-dimensional conducting rough surface and a dielectric rough surface are calculated with different frequencies and roughness values in the microwave band by using the method of moments, and the relationship between the bistatic scattering coefficient and the BRDF of a rough surface is expressed. From the theory of the parameters of the rough surface BRDF, the parameters of the BRDF are obtained using a genetic algorithm. The BRDF of a rough surface is calculated using the obtained parameter values. Further, the fitting values and theoretical calculations of the BRDF are compared, and the optimization results are in agreement with the theoretical calculation results. Finally, a reference for BRDF modeling of a Gaussian rough surface in the microwave band is provided by the proposed method. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Collection and corrections of oblique multiangle hyperspectral bidirectional reflectance imagery of the water surface

Science.gov (United States)

Bostater, Charles R.; Oney, Taylor S.

2017-10-01

Hyperspectral images of coastal waters in urbanized regions were collected from fixed platform locations. Surf zone imagery, images of shallow bays, lagoons and coastal waters are processed to produce bidirectional reflectance factor (BRF) signatures corrected for changing viewing angles. Angular changes as a function of pixel location within a scene are used to estimate changes in pixel size and ground sampling areas. Diffuse calibration targets collected simultaneously from within the image scene provides the necessary information for calculating BRF signatures of the water surface and shorelines. Automated scanning using a pushbroom hyperspectral sensor allows imagery to be collected on the order of one minute or less for different regions of interest. Imagery is then rectified and georeferenced using ground control points within nadir viewing multispectral imagery via image to image registration techniques. This paper demonstrates the above as well as presenting how spectra can be extracted along different directions in the imagery. The extraction of BRF spectra along track lines allows the application of derivative reflectance spectroscopy for estimating chlorophyll-a, dissolved organic matter and suspended matter concentrations at or near the water surface. Imagery is presented demonstrating the techniques to identify subsurface features and targets within the littoral and surf zones.

Modified polarized geometrical attenuation model for bidirectional reflection distribution function based on random surface microfacet theory.

Science.gov (United States)

Liu, Hong; Zhu, Jingping; Wang, Kai

2015-08-24

The geometrical attenuation model given by Blinn was widely used in the geometrical optics bidirectional reflectance distribution function (BRDF) models. Blinn's geometrical attenuation model based on symmetrical V-groove assumption and ray scalar theory causes obvious inaccuracies in BRDF curves and negatives the effects of polarization. Aiming at these questions, a modified polarized geometrical attenuation model based on random surface microfacet theory is presented by combining of masking and shadowing effects and polarized effect. The p-polarized, s-polarized and unpolarized geometrical attenuation functions are given in their separate expressions and are validated with experimental data of two samples. It shows that the modified polarized geometrical attenuation function reaches better physical rationality, improves the precision of BRDF model, and widens the applications for different polarization.

Extension of the Hapke bidirectional reflectance model to retrieve soil water content

Directory of Open Access Journals (Sweden)

G.-J. Yang

2011-07-01

Full Text Available Soil moisture links the hydrologic cycle and the energy budget of land surfaces by regulating latent heat fluxes. An accurate assessment of the spatial and temporal variation of soil moisture is important to the study of surface biogeophysical processes. Although remote sensing has proven to be one of the most powerful tools for obtaining land surface parameters, no effective methodology yet exists for in situ soil moisture measurement based on a Bidirectional Reflectance Distribution Function (BRDF model, such as the Hapke model. To retrieve and analyze soil moisture, this study applied the soil water parametric (SWAP-Hapke model, which introduced the equivalent water thickness of soil, to ground multi-angular and hyperspectral observations coupled with, Powell-Ant Colony Algorithm methods. The inverted soil moisture data resulting from our method coincided with in situ measurements (R² = 0.867, RMSE = 0.813 based on three selected bands (672 nm, 866 nm, 2209 nm. It proved that the extended Hapke model can be used to estimate soil moisture with high accuracy based on the field multi-angle and multispectral remote sensing data.

Degradation nonuniformity in the solar diffuser bidirectional reflectance distribution function.

Science.gov (United States)

Sun, Junqiang; Chu, Mike; Wang, Menghua

2016-08-01

The assumption of angular dependence stability of the solar diffuser (SD) throughout degradation is critical to the on-orbit calibration of the reflective solar bands (RSBs) in many satellite sensors. Recent evidence has pointed to the contrary, and in this work, we present a thorough investigative effort into the angular dependence of the SD degradation for the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite and for the twin Moderate-resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua spacecrafts. One common key step in the RSB calibration is the use of the SD degradation performance measured by an accompanying solar diffuser stability monitor (SDSM) as a valid substitute for the SD degradation factor in the direction of the RSB view. If SD degradations between these two respective directions do not maintain the same relative relationship over time, then the unmitigated use of the SDSM-measured SD degradation factor in the RSB calibration calculation will generate bias, and consequently, long-term drift in derived science products. We exploit the available history of the on-orbit calibration events to examine the response of the SDSM and the RSB detectors to the incident illumination reflecting off SD versus solar declination angle and show that the angular dependency, particularly at short wavelengths, evolves with respect to time. The generalized and the decisive conclusion is that the bidirectional reflectance distribution function (BRDF) of the SD degrades nonuniformly with respect to both incident and outgoing directions. Thus, the SDSM-based measurements provide SD degradation factors that are biased relative to the RSB view direction with respect to the SD. The analysis also reveals additional interesting phenomena, for example, the sharp behavioral change in the evolving angular dependence observed in Terra MODIS and SNPP VIIRS. For SNPP VIIRS the mitigation for this

A Bidirectional Subsurface Remote Sensing Reflectance Model Explicitly Accounting for Particle Backscattering Shapes

Science.gov (United States)

He, Shuangyan; Zhang, Xiaodong; Xiong, Yuanheng; Gray, Deric

2017-11-01

The subsurface remote sensing reflectance (rrs, sr-1), particularly its bidirectional reflectance distribution function (BRDF), depends fundamentally on the angular shape of the volume scattering functions (VSFs, m-1 sr-1). Recent technological advancement has greatly expanded the collection, and the knowledge of natural variability, of the VSFs of oceanic particles. This allows us to test the Zaneveld's theoretical rrs model that explicitly accounts for particle VSF shapes. We parameterized the rrs model based on HydroLight simulations using 114 VSFs measured in three coastal waters around the United States and in oceanic waters of North Atlantic Ocean. With the absorption coefficient (a), backscattering coefficient (bb), and VSF shape as inputs, the parameterized model is able to predict rrs with a root mean square relative error of ˜4% for solar zenith angles from 0 to 75°, viewing zenith angles from 0 to 60°, and viewing azimuth angles from 0 to 180°. A test with the field data indicates the performance of our model, when using only a and bb as inputs and selecting the VSF shape using bb, is comparable to or slightly better than the currently used models by Morel et al. and Lee et al. Explicitly expressing VSF shapes in rrs modeling has great potential to further constrain the uncertainty in the ocean color studies as our knowledge on the VSFs of natural particles continues to improve. Our study represents a first effort in this direction.

Comparison of ultraviolet Bi-directional Reflectance Distribution Function (BRDF) measurements of diffusers used in the calibration of the Total Ozone Mapping Spectrometer (TOMS)

OpenAIRE

Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.

2002-01-01

The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those instruments. To assess the ability of laboratories to provide accurate Ultra Violet (UV) diffuse BRDF measurements, a BRDF measurement comparison was initiated by the NASA Total Ozone Mapping Spectrom...

Exploration of a Polarized Surface Bidirectional Reflectance Model Using the Ground-Based Multiangle SpectroPolarimetric Imager

Directory of Open Access Journals (Sweden)

David J. Diner

2012-12-01

Full Text Available Accurate characterization of surface reflection is essential for retrieval of aerosols using downward-looking remote sensors. In this paper, observations from the Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI are used to evaluate a surface polarized bidirectional reflectance distribution function (PBRDF model. GroundMSPI is an eight-band spectropolarimetric camera mounted on a rotating gimbal to acquire pushbroom imagery of outdoor landscapes. The camera uses a very accurate photoelastic-modulator-based polarimetric imaging technique to acquire Stokes vector measurements in three of the instrument’s bands (470, 660, and 865 nm. A description of the instrument is presented, and observations of selected targets within a scene acquired on 6 January 2010 are analyzed. Data collected during the course of the day as the Sun moved across the sky provided a range of illumination geometries that facilitated evaluation of the surface model, which is comprised of a volumetric reflection term represented by the modified Rahman-Pinty-Verstraete function plus a specular reflection term generated by a randomly oriented array of Fresnel-reflecting microfacets. While the model is fairly successful in predicting the polarized reflection from two grass targets in the scene, it does a poorer job for two manmade targets (a parking lot and a truck roof, possibly due to their greater degree of geometric organization. Several empirical adjustments to the model are explored and lead to improved fits to the data. For all targets, the data support the notion of spectral invariance in the angular shape of the unpolarized and polarized surface reflection. As noted by others, this behavior provides valuable constraints on the aerosol retrieval problem, and highlights the importance of multiangle observations.

Monte Carlo simulation of spectral reflectance and BRDF of the bubble layer in the upper ocean.

Science.gov (United States)

Ma, Lanxin; Wang, Fuqiang; Wang, Chengan; Wang, Chengchao; Tan, Jianyu

2015-09-21

The presence of bubbles can significantly change the radiative properties of seawater and these changes will affect remote sensing and underwater target detection. In this work, the spectral reflectance and bidirectional reflectance characteristics of the bubble layer in the upper ocean are investigated using the Monte Carlo method. The Hall-Novarini (HN) bubble population model, which considers the effect of wind speed and depth on the bubble size distribution, is used. The scattering coefficients and the scattering phase functions of bubbles in seawater are calculated using Mie theory, and the inherent optical properties of seawater for wavelengths between 300 nm and 800 nm are related to chlorophyll concentration (Chl). The effects of bubble coating, Chl, and bubble number density on the spectral reflectance of the bubble layer are studied. The bidirectional reflectance distribution function (BRDF) of the bubble layer for both normal and oblique incidence is also investigated. The results show that bubble populations in clear waters under high wind speed conditions significantly influence the reflection characteristics of the bubble layer. Furthermore, the contribution of bubble populations to the reflection characteristics is mainly due to the strong backscattering of bubbles that are coated with an organic film.

Impacts of light-absorbing impurities on snow and their quantification with bidirectional reflectance measurements

Science.gov (United States)

Gritsevich, Maria; Peltoniemi, Jouni; Meinander, Outi; Dagsson-Waldhauserová, Pavla; Zubko, Nataliya; Hakala, Teemu; Virkkula, Aki; Svensson, Jonas; de Leeuw, Gerrit

2017-04-01

In order to quantify the effects of absorbing impurities on snow and define their contribution to the climate change, we have conducted a series of dedicated bidirectional reflectance measurements. Chimney soot, volcanic sand, and glaciogenic silt have been deposited on the snow in the controlled way. The bidirectional reflectance factors of these targets and untouched snow have been measured using the Finnish Geodetic Institute's field goniospectrometer FIGIFIGO, see, e.g., [1, 2] and references therein. It has been found that the contaminants darken the snow, and modify its appearance mostly as expected, with clear directional signal and modest spectral signal. A remarkable feature is the fact that any absorbing contaminant on snow enhances the metamorphosis under strong sunlight [3, 4]. Immediately after deposition, the contaminated snow surface appears darker than the pure snow in all viewing directions, but the heated soot particles start sinking down deeply into the snow in minutes. The nadir measurement remains darkest, but at larger zenith angles the surface of the soot-contaminated snow changes back to almost as white as clean snow. Thus, for on ground observer the darkening by impurities can be completely invisible, overestimating the albedo, but a nadir looking satellite sees the darkest points, now underestimating the albedo. After more time, also the nadir view brightens, and the remaining impurities may be biased towards more shadowed locations or less absorbing orientations by natural selection. This suggests that at noon the albedo should be lower than in the morning or afternoon. When sunlight stimulates more sinking than melting, albedo should be higher in the afternoon than in the morning, and vice versa when melting is dominating. Thus to estimate the effects caused by black carbon (BC) deposited on snow on climate changes may one need to take into account possible rapid diffusion of the BC inside the snow from its surface. When the snow melt

A new bidirectional heteroassociative memory encompassing correlational, competitive and topological properties.

Science.gov (United States)

Chartier, Sylvain; Giguère, Gyslain; Langlois, Dominic

2009-01-01

In this paper, we present a new recurrent bidirectional model that encompasses correlational, competitive and topological model properties. The simultaneous use of many classes of network behaviors allows for the unsupervised learning/categorization of perceptual patterns (through input compression) and the concurrent encoding of proximities in a multidimensional space. All of these operations are achieved within a common learning operation, and using a single set of defining properties. It is shown that the model can learn categories by developing prototype representations strictly from exposition to specific exemplars. Moreover, because the model is recurrent, it can reconstruct perfect outputs from incomplete and noisy patterns. Empirical exploration of the model's properties and performance shows that its ability for adequate clustering stems from: (1) properly distributing connection weights, and (2) producing a weight space with a low dispersion level (or higher density). In addition, since the model uses a sparse representation (k-winners), the size of topological neighborhood can be fixed, and no longer requires a decrease through time as was the case with classic self-organizing feature maps. Since the model's learning and transmission parameters are independent from learning trials, the model can develop stable fixed points in a constrained topological architecture, while being flexible enough to learn novel patterns.

Temporal dynamics of sand dune bidirectional reflectance characteristics for absolute radiometric calibration of optical remote sensing data

Science.gov (United States)

Coburn, Craig A.; Logie, Gordon S. J.

2018-01-01

Attempts to use pseudoinvariant calibration sites (PICS) for establishing absolute radiometric calibration of Earth observation (EO) satellites requires high-quality information about the nature of the bidirectional reflectance distribution function (BRDF) of the surfaces used for these calibrations. Past studies have shown that the PICS method is useful for evaluating the trend of sensors over time or for the intercalibration of sensors. The PICS method was not considered until recently for deriving absolute radiometric calibration. This paper presents BRDF data collected by a high-performance portable goniometer system to develop a temporal BRDF model for the Algodones Dunes in California. By sampling the BRDF of the sand surface at similar solar zenith angles to those normally encountered by EO satellites, additional information on the changing nature of the surface can improve models used to provide absolute radiometric correction. The results demonstrated that the BRDF of a reasonably simple sand surface was complex with changes in anisotropy taking place in response to changing solar zenith angles. For the majority of observation and illumination angles, the spectral reflectance anisotropy observed varied between 1% and 5% in patterns that repeat around solar noon.

Application of the three-component bidirectional reflectance distribution function model to Monte Carlo calculation of spectral effective emissivities of nonisothermal blackbody cavities.

Science.gov (United States)

Prokhorov, Alexander; Prokhorova, Nina I

2012-11-20

We applied the bidirectional reflectance distribution function (BRDF) model consisting of diffuse, quasi-specular, and glossy components to the Monte Carlo modeling of spectral effective emissivities for nonisothermal cavities. A method for extension of a monochromatic three-component (3C) BRDF model to a continuous spectral range is proposed. The initial data for this method are the BRDFs measured in the plane of incidence at a single wavelength and several incidence angles and directional-hemispherical reflectance measured at one incidence angle within a finite spectral range. We proposed the Monte Carlo algorithm for calculation of spectral effective emissivities for nonisothermal cavities whose internal surface is described by the wavelength-dependent 3C BRDF model. The results obtained for a cylindroconical nonisothermal cavity are discussed and compared with results obtained using the conventional specular-diffuse model.

Bidirectional reflectance distribution function /BRDF/ measurements of stray light suppression coatings for the Space Telescope /ST/

Science.gov (United States)

Griner, D. B.

1979-01-01

The paper considers the bidirectional reflectance distribution function (BRDF) of black coatings used on stray light suppression systems for the Space Telescope (ST). The ST stray light suppression requirement is to reduce earth, moon, and sun light in the focal plane to a level equivalent to one 23 Mv star per square arcsecond, an attenuation of 14 orders of magnitude. It is impractical to verify the performance of a proposed baffle system design by full scale tests because of the large size of the ST, so that a computer analysis is used to select the design. Accurate computer analysis requires a knowledge of the diffuse scatter at all angles from the surface of the coatings, for all angles of incident light. During the early phases of the ST program a BRDF scanner was built at the Marshall Space Flight Center to study the scatter from black materials; the measurement system is described and the results of measurements on samples proposed for use on the ST are presented.

The strong reflecting property and Harrington's Principle

OpenAIRE

Cheng, Yong

2015-01-01

In this paper we characterize the strong reflecting property for $L$-cardinals for all $\\omega_n$, characterize Harrington's Principle $HP(L)$ and its generalization and discuss the relationship between the strong reflecting property for $L$-cardinals and Harrington's Principle $HP(L)$.

An assessment of thin cloud detection by applying bidirectional reflectance distribution function model-based background surface reflectance using Geostationary Ocean Color Imager (GOCI): A case study for South Korea

Science.gov (United States)

Kim, Hye-Won; Yeom, Jong-Min; Shin, Daegeun; Choi, Sungwon; Han, Kyung-Soo; Roujean, Jean-Louis

2017-08-01

In this study, a new assessment of thin cloud detection with the application of bidirectional reflectance distribution function (BRDF) model-based background surface reflectance was undertaken by interpreting surface spectra characterized using the Geostationary Ocean Color Imager (GOCI) over a land surface area. Unlike cloud detection over the ocean, the detection of cloud over land surfaces is difficult due to the complicated surface scattering characteristics, which vary among land surface types. Furthermore, in the case of thin clouds, in which the surface and cloud radiation are mixed, it is difficult to detect the clouds in both land and atmospheric fields. Therefore, to interpret background surface reflectance, especially underneath cloud, the semiempirical BRDF model was used to simulate surface reflectance by reflecting solar angle-dependent geostationary sensor geometry. For quantitative validation, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data were used to make a comparison with the proposed cloud masking result. As a result, the new cloud masking scheme resulted in a high probability of detection (POD = 0.82) compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) (POD = 0.808) for all cloud cases. In particular, the agreement between the CALIPSO cloud product and new GOCI cloud mask was over 94% when detecting thin cloud (e.g., altostratus and cirrus) from January 2014 to June 2015. This result is relatively high in comparison with the result from the MODIS Collection 6 cloud mask product (MYD35).

Bidirectional fiber-wireless and fiber-VLLC transmission system based on an OEO-based BLS and a RSOA.

Science.gov (United States)

Lu, Hai-Han; Li, Chung-Yi; Lu, Ting-Chien; Wu, Chang-Jen; Chu, Chien-An; Shiva, Ajay; Mochii, Takao

2016-02-01

A bidirectional fiber-wireless and fiber-visible-laser-light-communication (VLLC) transmission system based on an optoelectronic oscillator (OEO)-based broadband light source (BLS) and a reflective semiconductor optical amplifier (RSOA) is proposed and experimentally demonstrated. Through an in-depth observation of such bidirectional fiber-wireless and fiber-VLLC transmission systems, good bit error rate performances are obtained over a 40 km single-mode fiber and a 10 m RF/optical wireless transport. Such a bidirectional fiber-wireless and fiber-VLLC transmission system is an attractive option for providing broadband integrated services.

Exact bidirectional X -wave solutions in fiber Bragg gratings

Science.gov (United States)

Efremidis, Nikolaos K.; Nye, Nicholas S.; Christodoulides, Demetrios N.

2017-10-01

We find exact solutions describing bidirectional pulses propagating in fiber Bragg gratings. They are derived by solving the coupled-mode theory equations and are expressed in terms of products of modified Bessel functions with algebraic functions. Depending on the values of the two free parameters, the general bidirectional X -wave solution can also take the form of a unidirectional pulse. We analyze the symmetries and the asymptotic properties of the solutions and also discuss additional waveforms that are obtained by interference of more than one solution. Depending on their parameters, such pulses can create a sharp focus with high contrast.

A Monte Carlo reflectance model for soil surfaces with three-dimensional structure

Science.gov (United States)

Cooper, K. D.; Smith, J. A.

1985-01-01

A Monte Carlo soil reflectance model has been developed to study the effect of macroscopic surface irregularities larger than the wavelength of incident flux. The model treats incoherent multiple scattering from Lambertian facets distributed on a periodic surface. Resulting bidirectional reflectance distribution functions are non-Lambertian and compare well with experimental trends reported in the literature. Examples showing the coupling of the Monte Carlo soil model to an adding bidirectional canopy of reflectance model are also given.

Structural properties of reflected Lévy processes

DEFF Research Database (Denmark)

Andersen, Lars Nørvang; Mandjes, Michel

This paper considers a number of structural properties of reflected Lévy processes, where both one-sided reflection (at 0) and two-sided reflection (at both 0 and K > 0) are examined. With Vt being the position of the reflected process at time t, we focus on the analysis of ζ(t) := EVt and ξ(t) :...

Polarization properties and microfacet-based modelling of white, grey and coloured matte diffuse reflection standards

Science.gov (United States)

Quast, T.; Schirmacher, A.; Hauer, K.-O.; Koo, A.

2018-02-01

To elucidate the influence of polarization in diffuse reflectometry, we performed a series of measurements in several bidirectional geometries and determined the Stokes parameters of the diffusely reflected radiation. Different types of matte reflection standards were used, including several common white standards and ceramic colour standards. The dependence of the polarization on the sample type, wavelength and geometry have been studied systematically, the main influence factors have been identified: The effect is largest at large angles of incidence or detection and at wavelengths where the magnitude of the reflectance is small. The results for the colour standards have been modelled using a microfacet-based reflection theory which is derived from the well-known model of Torrance and Sparrow. Although the theory is very simple and only has three free parameters, the agreement with the measured data is very good, all essential features of the data can be reproduced by the model.

A Statistical Theory of Bidirectionality

Science.gov (United States)

DeLoach, Richard; Ulbrich, Norbert

2013-01-01

Original concepts related to the quantification and assessment of bidirectionality in strain-gage balances were introduced by Ulbrich in 2012. These concepts are extended here in three ways: 1) the metric originally proposed by Ulbrich is normalized, 2) a categorical variable is introduced in the regression analysis to account for load polarity, and 3) the uncertainty in both normalized and non-normalized bidirectionality metrics is quantified. These extensions are applied to four representative balances to assess the bidirectionality characteristics of each. The paper is tutorial in nature, featuring reviews of certain elements of regression and formal inference. Principal findings are that bidirectionality appears to be a common characteristic of most balance outputs and that unless it is taken into account, it is likely to consume the entire error budget of a typical balance calibration experiment. Data volume and correlation among calibration loads are shown to have a significant impact on the precision with which bidirectionality metrics can be assessed.

Retrieval and Validation of aerosol optical properties from AHI measurements: impact of surface reflectance assumption

Science.gov (United States)

Lim, H.; Choi, M.; Kim, J.; Go, S.; Chan, P.; Kasai, Y.

2017-12-01

This study attempts to retrieve the aerosol optical properties (AOPs) based on the spectral matching method, with using three visible and one near infrared channels (470, 510, 640, 860nm). This method requires the preparation of look-up table (LUT) approach based on the radiative transfer modeling. Cloud detection is one of the most important processes for guaranteed quality of AOPs. Since the AHI has several infrared channels, which are very advantageous for cloud detection, clouds can be removed by using brightness temperature difference (BTD) and spatial variability test. The Yonsei Aerosol Retrieval (YAER) algorithm is basically utilized on a dark surface, therefore a bright surface (e.g., desert, snow) should be removed first. Then we consider the characteristics of the reflectance of land and ocean surface using three visible channels. The known surface reflectivity problem in high latitude area can be solved in this algorithm by selecting appropriate channels through improving tests. On the other hand, we retrieved the AOPs by obtaining the visible surface reflectance using NIR to normalized difference vegetation index short wave infrared (NDVIswir) relationship. ESR tends to underestimate urban and cropland area, we improved the visible surface reflectance considering urban effect. In this version, ocean surface reflectance is using the new cox and munk method which considers ocean bidirectional reflectance distribution function (BRDF). Input of this method has wind speed, chlorophyll, salinity and so on. Based on validation results with the sun-photometer measurement in AErosol Robotic NETwork (AERONET), we confirm that the quality of Aerosol Optical Depth (AOD) from the YAER algorithm is comparable to the product from the Japan Aerospace Exploration Agency (JAXA) retrieval algorithm. Our future update includes a consideration of improvement land surface reflectance by hybrid approach, and non-spherical aerosols. This will improve the quality of YAER

Modifying Geometric-Optical Bidirectional Reflectance Model for Direct Inversion of Forest Canopy Leaf Area Index

Directory of Open Access Journals (Sweden)

Congrong Li

2015-08-01

Full Text Available Forest canopy leaf area index (LAI inversion based on remote sensing data is an important method to obtain LAI. Currently, the most widely-used model to achieve forest canopy structure parameters is the Li-Strahler geometric-optical bidirectional reflectance model, by considering the effect of crown shape and mutual shadowing, which is referred to as the GOMS model. However, it is difficult to retrieve LAI through the GOMS model directly because LAI is not a fundamental parameter of the model. In this study, a gap probability model was used to obtain the relationship between the canopy structure parameter nR2 and LAI. Thus, LAI was introduced into the GOMS model as an independent variable by replacing nR2 The modified GOMS (MGOMS model was validated by application to Dayekou in the Heihe River Basin of China. The LAI retrieved using the MGOMS model with optical multi-angle remote sensing data, high spatial resolution images and field-measured data was in good agreement with the field-measured LAI, with an R-square (R2 of 0.64, and an RMSE of 0.67. The results demonstrate that the MGOMS model obtained by replacing the canopy structure parameter nR2 of the GOMS model with LAI can be used to invert LAI directly and precisely.

Polarised Multiangular Reflectance Measurements Using the Finnish Geodetic Institute Field Goniospectrometer

Directory of Open Access Journals (Sweden)

Jouni Peltoniemi

2009-05-01

Full Text Available The design, operation, and properties of the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO are presented. FIGIFIGO is a portable instrument for the measurement of surface Bidirectional Reflectance Factor (BRF for samples with diameters of 10 – 50 cm. A set of polarising optics enable the measurement of linearly polarised BRF over the full solar spectrum (350 – 2,500 nm. FIGIFIGO is designed mainly for field operation using sunlight, but operation in a laboratory environment is also possible. The acquired BRF have an accuracy of 1 – 5% depending on wavelength, sample properties, and measurement conditions. The angles are registered at accuracies better than 2°. During 2004 – 2008, FIGIFIGO has been used in the measurement of over 150 samples, all around northern Europe. The samples concentrate mostly on boreal forest understorey, snow, urban surfaces, and reflectance calibration surfaces.

The effect of bi-directional reflectance distribution function on the estimation of vegetation indices and leaf area index (LAI): A case study of the vegetation in succession stages after forest fire in northwestern Canada

International Nuclear Information System (INIS)

Hasegawa, K.; Matsuyama, H.; Tsuzuki, H.; Sweda, T.

2006-01-01

The effect of the dependence of the satellite data on sun/sensor geometry must be considered in the case of monitoring vegetation from satellites. Vegetation structure causes uneven scattering of sunlight, which is expressed by bi-directional reflectance distribution function (BRDF). The purpose of this study is to estimate the effect of BRDF of monitoring vegetation using the reflectance of visible and near-infrared bands. We investigated the vegetation in succession stages after forest fire (main species: spruce) in the northwestern Canada. BRF (Bidirectional Reflectance Factor) was measured in the seven sites of some succession stages, along with the measurements of leaf area index (LAI) and biomass. The main results obtained in this study are summarized as follows. (1) In each site, the difference of Normalized Difference Vegetation Index (NDVI) value around 0.1-0.2 was caused by BRDF when the sensor angle was changed from -15deg to 15 deg, being equivalent to the standard image of IKONOS. Also, LAI estimated by NDVI varied from 22% to 65% of the average. (2) The robustness of other vegetation indices to BRDF was compared. The reflectance of the near-infrared band normalized by the sum of other bands (nNIR), and Global Environmental Monitoring Index (GEMI) were investigated along with NDVI. It is clarified that nNIR was most robust in the site where vegetation existed. GEMI was most robust in the sites of scarce vegetation, while NDVI was strongly affected by BRDF in such sites

A Data-Driven Reflectance Model

OpenAIRE

Matusik, Wojciech; Pfister, Hanspeter; Brand, Matt; McMillan, Leonard

2003-01-01

We present a generative model for isotropic bidirectional reflectance distribution functions (BRDFs) based on acquired reflectance data. Instead of using analytical reflectance models, we represent each BRDF as a dense set of measurements. This allows us to interpolate and extrapolate in the space of acquired BRDFs to create new BRDFs. We treat each acquired BRDF as a single high-dimensional vector taken from a space of all possible BRDFs. We apply both linear (subspace) and non-linear (manif...

Reflected Sunlight Reduction and Characterization for a Deep-Space Optical Receiver Antenna (DSORA)

Science.gov (United States)

Clymer, B. D.

1990-01-01

A baffle system for the elimination of first-order specular and diffuse reflection of sunlight from the sunshade of a deep-space optical receiver telescope is presented. This baffle system consists of rings of 0.5cm blades spaced 2.5 cm apart on the walls of GO hexagonal sunshade tubes that combine to form the telescope sunshade. The shadow cast by the blades, walls, and rims of the tubes prevent all first-order reflections of direct sunlight from reaching the primary mirror of the telescope. A reflection model of the sunshade without baffles is also presented for comparison. Since manufacturers of absorbing surfaces do not measure data near grazing incidence, the reflection properties at anticipated angles of incidence must be characterized. A description of reflection from matte surfaces in term of bidirectional reflection distribution function (BRDF) is presented along with a discussion of measuring BRDF near grazing incidence.

About the use of reflectance terminology in imaging spectroscopy

NARCIS (Netherlands)

Schaepman-Strub, G.; Schaepman, M.E.; Dangel, S.; Painter, T.; Martonchik, J.

2005-01-01

Analysing databases, field and airborne spectrometer data, modelling studies and publications, a lack of consistency in the use of definitions and terminology of reflectance quantities can be observed. One example is the term `BRDF¿ (bidirectional reflectance distribution function) assigned to

Transmission and reflection properties of terahertz fractal metamaterials

DEFF Research Database (Denmark)

Malureanu, Radu; Lavrinenko, Andrei; Cooke, David

2010-01-01

We use THz time-domain spectroscopy to investigate transmission and reflection properties of metallic fractal metamaterial structures. We observe loss of free-space energy at certain resonance frequencies, indicating excitation of surface modes of the metamaterial.......We use THz time-domain spectroscopy to investigate transmission and reflection properties of metallic fractal metamaterial structures. We observe loss of free-space energy at certain resonance frequencies, indicating excitation of surface modes of the metamaterial....

Modeling bidirectional radiance measurements collected by the advanced solid-state array spectroradiometer (ASAS) over Oregon transect conifer forests

International Nuclear Information System (INIS)

Abuelgasim, A.A.; Strahler, A.H.

1994-01-01

A geometric-optical model of the bidirectional reflectance of a forest canopy, developed by Li and Strahler, fits observed directional radiance measurements with good accuracy. This model treats the forest cover as a scene of discrete, three-dimensional objects (trees) that are illuminated and viewed from different positions in the hemisphere. The shapes of the objects, their count densities and patterns of placement, are the driving variables, and they condition the mixture of sunlit and shaded objects and background that are observed from a particular viewing direction, given a direction of illumination. This mixture, in turn, controls the brightness apparent to an observer or a radiometric instrument. The Advanced Solid-State Array Spectroradiometer (ASAS) was used to validate this model. This aircraft sensor presently acquires images in 29 spectral bands in the range (465–871 nm) and is pointable fore-and-aft, allowing directional measurements of radiance as a target is approached and imaged at view angles ranging ± 45° from nadir. Through atmospheric correction, ASAS radiances were reduced to bidirectional reflectance factors (BRFs). These were compared to corresponding BRF values computed from the Li-Strahler model using, wherever possible, ground measured component BRFs for calibration. The comparisons showed a good match between the modeled and measured reflectance factors for four of the five Oregon Transect Sites. Thus, the geometric-optical approach provides a realistic model for the bidirectional reflectance distribution function of such natural vegetation canopies. Further modifications are suggested to improve the predicted BRFs and yield still better results. (author)

Bidirectional optical rotation of cells

Directory of Open Access Journals (Sweden)

Jiyi Wu

2017-08-01

Full Text Available Precise and controlled rotation manipulation of cells is extremely important in biological applications and biomedical studies. Particularly, bidirectional rotation manipulation of a single or multiple cells is a challenge for cell tomography and analysis. In this paper, we report an optical method that is capable of bidirectional rotation manipulation of a single or multiple cells. By launching a laser beam at 980 nm into dual-beam tapered fibers, a single or multiple cells in solutions can be trapped and rotated bidirectionally under the action of optical forces. Moreover, the rotational behavior can be controlled by altering the relative distance between the two fibers and the input optical power. Experimental results were interpreted by numerical simulations.

Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems

Science.gov (United States)

Koutserimpas, Theodoros T.; Alù, Andrea; Fleury, Romain

2018-01-01

Parity-time (PT )-symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT -symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follows the Mathieu equation, can be described by a PT -symmetric scattering matrix, whose PT -breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out of phase, we create PT -symmetric time-Floquet systems that feature exceptional scattering properties, such as coherent perfect absorption (CPA)-laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT -symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.

Comparative analyses of bidirectional promoters in vertebrates

Directory of Open Access Journals (Sweden)

Taylor James

2008-05-01

Full Text Available Abstract Background Orthologous genes with deep phylogenetic histories are likely to retain similar regulatory features. In this report we utilize orthology assignments for pairs of genes co-regulated by bidirectional promoters to map the ancestral history of the promoter regions. Results Our mapping of bidirectional promoters from humans to fish shows that many such promoters emerged after the divergence of chickens and fish. Furthermore, annotations of promoters in deep phylogenies enable detection of missing data or assembly problems present in higher vertebrates. The functional importance of bidirectional promoters is indicated by selective pressure to maintain the arrangement of genes regulated by the promoter over long evolutionary time spans. Characteristics unique to bidirectional promoters are further elucidated using a technique for unsupervised classification, known as ESPERR. Conclusion Results of these analyses will aid in our understanding of the evolution of bidirectional promoters, including whether the regulation of two genes evolved as a consequence of their proximity or if function dictated their co-regulation.

A bidirectional association between cognitive ability in young adulthood and epilepsy

DEFF Research Database (Denmark)

Osler, Merete; Mortensen, Erik L; Christensen, Kaare

2018-01-01

Aim: To investigate the bidirectional association between cognitive ability in young adulthood and epilepsy. Methods: This cohort study included 1 159 076 men enrolled in the mandatory conscription board examination from the Danish Conscription Database (DCD; 658 465 men examined 1957-84), the Da......Aim: To investigate the bidirectional association between cognitive ability in young adulthood and epilepsy. Methods: This cohort study included 1 159 076 men enrolled in the mandatory conscription board examination from the Danish Conscription Database (DCD; 658 465 men examined 1957...... with epilepsy before conscription, and they had about 0.25 standard deviation (SD) lower cognitive scores than men without epilepsy. The largest difference in cognition was seen for those with the largest number of hospital contacts. A total of 22 364 (1.9%) men developed epilepsy, and cognitive ability......: The cognitive impairment seen in adults with epilepsy seems to reflect combined effects of epileptic processes and lower premorbid cognitive ability....

A BRDF-BPDF database for the analysis of Earth target reflectances

Science.gov (United States)

Breon, Francois-Marie; Maignan, Fabienne

2017-01-01

Land surface reflectance is not isotropic. It varies with the observation geometry that is defined by the sun, view zenith angles, and the relative azimuth. In addition, the reflectance is linearly polarized. The reflectance anisotropy is quantified by the bidirectional reflectance distribution function (BRDF), while its polarization properties are defined by the bidirectional polarization distribution function (BPDF). The POLDER radiometer that flew onboard the PARASOL microsatellite remains the only space instrument that measured numerous samples of the BRDF and BPDF of Earth targets. Here, we describe a database of representative BRDFs and BPDFs derived from the POLDER measurements. From the huge number of data acquired by the spaceborne instrument over a period of 7 years, we selected a set of targets with high-quality observations. The selection aimed for a large number of observations, free of significant cloud or aerosol contamination, acquired in diverse observation geometries with a focus on the backscatter direction that shows the specific hot spot signature. The targets are sorted according to the 16-class International Geosphere-Biosphere Programme (IGBP) land cover classification system, and the target selection aims at a spatial representativeness within the class. The database thus provides a set of high-quality BRDF and BPDF samples that can be used to assess the typical variability of natural surface reflectances or to evaluate models. It is available freely from the PANGAEA website (PANGAEA.864090" target="_blank">doi:10.1594/PANGAEA.864090). In addition to the database, we provide a visualization and analysis tool based on the Interactive Data Language (IDL). It allows an interactive analysis of the measurements and a comparison against various BRDF and BPDF analytical models. The present paper describes the input data, the selection principles, the database format, and the analysis tool

Use of asymmetric bidirectional catheters with different curvature radius for catheter ablation of cardiac arrhythmias.

Science.gov (United States)

Mantziari, Lilian; Suman-Horduna, Irina; Gujic, Marko; Jones, David G; Wong, Tom; Markides, Vias; Foran, John P; Ernst, Sabine

2013-06-01

The impact of recently introduced asymmetric bidirectional ablation catheters on procedural parameters and acute success rates of ablation procedures is unknown. We retrospectively analyzed data regarding ablations using a novel bidirectional catheter in a tertiary cardiac center and compared these in 1:5 ratio with a control group of procedures matched for age, gender, operator, and ablation type. A total of 50 cases and 250 controls of median age 60 (50-68) years were studied. Structural heart disease was equally prevalent in both groups (39%) while history of previous ablations was more common in the study arm (54% vs 30%, P = 0.001). Most of the ablation cases were for atrial fibrillation (46%), followed by atrial tachycardia (28%), supraventricular tachycardia (12%), and ventricular tachycardia (14%). Median procedure duration was 128 (52-147) minutes with the bidirectional, versus 143 (105-200) minutes with the conventional catheter (P = 0.232), and median fluoroscopy time was 17 (10-34) minutes versus 23 (12-39) minutes, respectively (P = 0.988). There was a trend toward a lower procedure duration for the atrial tachycardia ablations, 89 (52-147) minutes versus 130 (100-210) minutes, P = 0.064. The procedure was successfully completed in 96% of the bidirectional versus 84% of the control cases (P = 0.151). A negative correlation was observed between the relative fluoroscopy duration and the case number (r = -0.312, P = 0.028), reflecting the learning curve for the bidirectional catheter. The introduction of the bidirectional catheter resulted in no prolongation of procedure parameters and similar success rates, while there was a trend toward a lower procedure duration for atrial tachycardia ablations. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.

[Reflectance of sea ice in Liaodong Bay].

Science.gov (United States)

Xu, Zhan-tang; Yang, Yue-zhong; Wang, Gui-fen; Cao, Wen-xi; Kong, Xiang-peng

2010-07-01

In the present study, the relationships between sea ice albedo and the bidirectional reflectance distribution in Liaodong Bay were investigated. The results indicate that: (1) sea ice albedo alpha(lambda) is closely related to the components of sea ice, the higher the particulate concentration in sea ice surface is, the lower the sea ice albedo alpha(lambda) is. On the contrary, the higher the bubble concentration in sea ice is, the higher sea ice albedo alpha(lambda) is. (2) Sea ice albedo alpha(lambda) is similar to the bidirectional reflectance factor R(f) when the probe locates at nadir. The R(f) would increase with the increase in detector zenith theta, and the correlation between R(f) and the detector azimuth would gradually increase. When the theta is located at solar zenith 63 degrees, the R(f) would reach the maximum, and the strongest correlation is also shown between the R(f) and the detector azimuth. (3) Different types of sea ice would have the different anisotropic reflectance factors.

Bidirectional waveguide coupling with plasmonic Fano nanoantennas

Energy Technology Data Exchange (ETDEWEB)

Guo, Rui; Decker, Manuel, E-mail: manuel.decker@anu.edu.au; Staude, Isabelle; Neshev, Dragomir N.; Kivshar, Yuri S. [Nonlinear Physics Centre and Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)

2014-08-04

We introduce the concept of a bidirectional, compact single-element Fano nanoantenna that allows for directional coupling of light in opposite directions of a high-index dielectric waveguide for two different operation wavelengths. We utilize a Fano resonance to tailor the radiation phases of a gold nanodisk and a nanoslit that is inscribed into the nanodisk to realize bidirectional scattering. We show that this Fano nanoantenna operates as a bidirectional waveguide coupler at telecommunication wavelengths and, thus, is ideally suitable for integrated wavelength-selective light demultiplexing.

Generalized model of a bidirectional DC-DC converter

Science.gov (United States)

Hinov, Nikolay; Arnaudov, Dimitar; Penev, Dimitar

2017-12-01

The following paperwork presents models of bidirectional converters. A classic bidirectional converter and a new bidirectional circuit based on a ZCS resonant converter are investigated and compared. The developed models of these converters allow comparison between their characteristics showing their advantages and disadvantages. The models allow precise models of energy storage elements to be implemented as well, which is useful for examination of energy storage systems.

Normalization of time-series satellite reflectance data to a standard sun-target-sensor geometry using a semi-empirical model

Science.gov (United States)

Zhao, Yongguang; Li, Chuanrong; Ma, Lingling; Tang, Lingli; Wang, Ning; Zhou, Chuncheng; Qian, Yonggang

2017-10-01

Time series of satellite reflectance data have been widely used to characterize environmental phenomena, describe trends in vegetation dynamics and study climate change. However, several sensors with wide spatial coverage and high observation frequency are usually designed to have large field of view (FOV), which cause variations in the sun-targetsensor geometry in time-series reflectance data. In this study, on the basis of semiempirical kernel-driven BRDF model, a new semi-empirical model was proposed to normalize the sun-target-sensor geometry of remote sensing image. To evaluate the proposed model, bidirectional reflectance under different canopy growth conditions simulated by Discrete Anisotropic Radiative Transfer (DART) model were used. The semi-empirical model was first fitted by using all simulated bidirectional reflectance. Experimental result showed a good fit between the bidirectional reflectance estimated by the proposed model and the simulated value. Then, MODIS time-series reflectance data was normalized to a common sun-target-sensor geometry by the proposed model. The experimental results showed the proposed model yielded good fits between the observed and estimated values. The noise-like fluctuations in time-series reflectance data was also reduced after the sun-target-sensor normalization process.

85 km Long Reach PON System Using a Reflective SOA-EA Modulator and Distributed Raman Fiber Amplification

DEFF Research Database (Denmark)

Tafur Monroy, Idelfonso; Öhman, Filip; Yvind, Kresten

2006-01-01

We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit......We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit...

Dynamic Bidirectional Reflectance Distribution Functions: Measurement and Representation

Science.gov (United States)

2008-02-01

be included in the harmonic fits. Other sets of orthogonal functions such as Zernike polynomials have also been used to characterize BRDF and could...reflectance spectra of 3D objects,” Proc. SPIE 4663, 370–378 2001. 13J. R. Shell II, C. Salvagio, and J. R. Schott, “A novel BRDF measurement technique

There is no bidirectional hot-spot in Sentinel-2 data

Science.gov (United States)

Li, Z.; Roy, D. P.; Zhang, H.

2017-12-01

The Sentinel-2 multi-spectral instrument (MSI) acquires reflective wavelength observations with directional effects due to surface reflectance anisotropy, often described by the bidirectional reflectance distribution function (BRDF). Recently, we quantified Sentinel-2A (S2A) BRDF effects for 20° × 10° of southern Africa sensed in January and in April 2016 and found maximum BRDF effects for the January data and at the western scan edge, i.e., in the back-scatter direction (Roy et al. 2017). The hot-spot is the term used to describe the increased directional reflectance that occurs over most surfaces when the solar and viewing directions coincide, and has been observed in wide-field of view data such as MODIS. Recently, we observed that Landsat data will not have a hot-spot because the global annual minimum solar zenith angle is more than twice the maximum view zenith angle (Zhang et al. 2016). This presentation examines if there is a S2A hot-spot which may be possible as it has a wider field of view (20.6°) and higher orbit (786 km) than Landsat. We examined a global year of S2A metadata extracted using the Committee on Earth Observation Satellite Visualization Environment (COVE) tool, computed the solar zenith angles in the acquisition corners, and ranked the acquisitions by the solar zenith angle in the back-scatter direction. The available image data for the 10 acquisitions with the smallest solar zenith angle over the year were ordered from the ESA and their geometries examined in detail. The acquisition closest to the hot-spot had a maximum scattering angle of 173.61° on its western edge (view zenith angle 11.91°, solar zenith angle 17.97°) and was acquired over 60.80°W 24.37°N on June 2nd 2016. Given that hot-spots are only apparent when the scattering angle is close to 180° we conclude from this global annual analysis that there is no hot-spot in Sentinel-2 data. Roy, D.P, Li, J., Zhang, H.K., Yan, L., Huang, H., Li, Z., 2017, Examination of

Intergenerational Transmission in a Bidirectional Context

Directory of Open Access Journals (Sweden)

Jan De Mol

2013-07-01

Full Text Available Traditional approaches to the study of parent-child relationships view intergenerational transmission as a top-down phenomenon in which parents transfer their values, beliefs, and practices to their children. Furthermore, the focus of these unidirectional approaches regarding children's internalisation processes is on continuity or the transmission of similar values, beliefs, and practices from parents to children. Analogous unidirectional perspectives have also influenced the domain of family therapy. In this paper a cognitive-bidirectional and dialectical model of dynamics in parent-child relationships is discussed in which the focus is on continual creation of novel meanings and not just reproduction of old ones in the bidirectional transmission processes between parents and children. Parents and children are addressed as full and equally agents in their interdependent relationship, while these relational dynamics are embedded within culture. This cultural context complicates bidirectional transmission influences in the parent-child relationship as both parents and children are influenced by many other contexts. Further, current research in the domain of parent-child relationships and current concepts of intergenerational transmission in family therapy are reviewed from a bidirectional cognitive-dialectical perspective.

Angular dependance of spectral reflection for different materials

Science.gov (United States)

Kiefer, Pascal M.

2017-10-01

Parameters like the sun angle as well as the measurement angle mostly are not taken into account when simulating because their influence on the reflectivity is weak. Therefore the impact of a changing measurement and illumination angle on the reflectivity is investigated. Furthermore the impact of humidity and chlorophyll in the scenery is studied by analyzing reflectance spectra of different vegetative background areas. It is shown that the measurement as well as the illumination angle has an important influence on the absolute reflection values which raises the importance of measurements of the bidirectional reflectance distribution function (BRDF).

Convergence analysis of stochastic hybrid bidirectional associative memory neural networks with delays

International Nuclear Information System (INIS)

Wan Li; Zhou Qinghua

2007-01-01

The stability property of stochastic hybrid bidirectional associate memory (BAM) neural networks with discrete delays is considered. Without assuming the symmetry of synaptic connection weights and the monotonicity and differentiability of activation functions, the delay-independent sufficient conditions to guarantee the exponential stability of the equilibrium solution for such networks are given by using the nonnegative semimartingale convergence theorem

Convergence analysis of stochastic hybrid bidirectional associative memory neural networks with delays

Science.gov (United States)

Wan, Li; Zhou, Qinghua

2007-10-01

The stability property of stochastic hybrid bidirectional associate memory (BAM) neural networks with discrete delays is considered. Without assuming the symmetry of synaptic connection weights and the monotonicity and differentiability of activation functions, the delay-independent sufficient conditions to guarantee the exponential stability of the equilibrium solution for such networks are given by using the nonnegative semimartingale convergence theorem.

A bidirectional Optimality Theoretic analysis of multiple negative ...

African Journals Online (AJOL)

IT

6 All examples in this paper are colloquial Afrikaans unless otherwise ...... and bidirectional optimisation over these form-meaning pairs results in the selection of one or ..... Imperfective and perfective habituals in Polish: A bi-directional.

Detailed validation of the bidirectional effect in various Case 1 waters for application to ocean color imagery

Directory of Open Access Journals (Sweden)

K. J. Voss

2007-09-01

Full Text Available The radiance viewed from the ocean depends on the illumination and viewing geometry along with the water properties, and this variation is called the bidirectional effect. This bidirectional effect depends on the inherent optical properties of the water, including the volume scattering function, and is important when comparing data from different satellite sensors. The current model of f/Q, which contains the bidirectional effect, by Morel et al. (2002 depends on modeled, not measured, water parameters, thus must be carefully validated. In this paper we combined upwelling radiance distribution data from several cruises, in varied water types and with a wide range of solar zenith angles. We compared modeled and measured L_view/L_nadir and found that the average difference between the model and data was less than 0.01, while the RMS difference between the model and data was on the order of 0.02–0.03. This is well within the statistical noise of the data, which was on the order of 0.04–0.05, due to environmental noise sources such as wave focusing.

Reflectance Modeling

Science.gov (United States)

Smith, J. A.; Cooper, K.; Randolph, M.

1984-01-01

A classical description of the one dimensional radiative transfer treatment of vegetation canopies was completed and the results were tested against measured prairie (blue grama) and agricultural canopies (soybean). Phase functions are calculated in terms of directly measurable biophysical characteristics of the canopy medium. While the phase functions tend to exhibit backscattering anisotropy, their exact behavior is somewhat more complex and wavelength dependent. A Monte Carlo model was developed that treats soil surfaces with large periodic variations in three dimensions. A photon-ray tracing technology is used. Currently, the rough soil surface is described by analytic functions and appropriate geometric calculations performed. A bidirectional reflectance distribution function is calculated and, hence, available for other atmospheric or canopy reflectance models as a lower boundary condition. This technique is used together with an adding model to calculate several cases where Lambertian leaves possessing anisotropic leaf angle distributions yield non-Lambertian reflectance; similar behavior is exhibited for simulated soil surfaces.

A Bidirectional Generalized Synchronization Theorem-Based Chaotic Pseudo-random Number Generator

Directory of Open Access Journals (Sweden)

Han Shuangshuang

2013-07-01

Full Text Available Based on a bidirectional generalized synchronization theorem for discrete chaos system, this paper introduces a new 5-dimensional bidirectional generalized chaos synchronization system (BGCSDS, whose prototype is a novel chaotic system introduced in [12]. Numerical simulation showed that two pair variables of the BGCSDS achieve generalized chaos synchronization via a transform H.A chaos-based pseudo-random number generator (CPNG was designed by the new BGCSDS. Using the FIPS-140-2 tests issued by the National Institute of Standard and Technology (NIST verified the randomness of the 1000 binary number sequences generated via the CPNG and the RC4 algorithm respectively. The results showed that all the tested sequences passed the FIPS-140-2 tests. The confidence interval analysis showed the statistical properties of the randomness of the sequences generated via the CPNG and the RC4 algorithm do not have significant differences.

Properties of backward electromagnetic waves and negative reflection in ferrite films

International Nuclear Information System (INIS)

Vashkovsky, Anatolii V; Lock, Edwin H

2006-01-01

For a backward electromagnetic wave (magnetostatic wave) in a ferrite film, reflection from a perfect mirror formed by the straight edge of the film is investigated experimentally and theoretically. It is found that when the incident wave is collinear (the group velocity vector and the wave vector have opposite directions), negative reflection occurs at any angle of incidence, i.e., the incident and reflected beams are on the same side of the normal to the boundary. It is discovered that a noncollinear backward wave is nonreciprocal in the sense that its energy can be localized both near the surface and in the middle of the film. This property, previously observed only for surface magnetostatic waves, provides both the efficiency of generating and receiving the wave and the possibility of observing the reflected beam. A situation is realized where wave reflection results in two reflected beams. The properties of backward electromagnetic waves propagating in ferrite films are briefly analyzed. (methodological notes)

Image Captioning with Deep Bidirectional LSTMs

OpenAIRE

Wang, Cheng; Yang, Haojin; Bartz, Christian; Meinel, Christoph

2016-01-01

This work presents an end-to-end trainable deep bidirectional LSTM (Long-Short Term Memory) model for image captioning. Our model builds on a deep convolutional neural network (CNN) and two separate LSTM networks. It is capable of learning long term visual-language interactions by making use of history and future context information at high level semantic space. Two novel deep bidirectional variant models, in which we increase the depth of nonlinearity transition in different way, are propose...

Familiarity Detection is an Intrinsic Property of Cortical Microcircuits with Bidirectional Synaptic Plasticity.

Science.gov (United States)

Zhang, Xiaoyu; Ju, Han; Penney, Trevor B; VanDongen, Antonius M J

2017-01-01

Humans instantly recognize a previously seen face as "familiar." To deepen our understanding of familiarity-novelty detection, we simulated biologically plausible neural network models of generic cortical microcircuits consisting of spiking neurons with random recurrent synaptic connections. NMDA receptor (NMDAR)-dependent synaptic plasticity was implemented to allow for unsupervised learning and bidirectional modifications. Network spiking activity evoked by sensory inputs consisting of face images altered synaptic efficacy, which resulted in the network responding more strongly to a previously seen face than a novel face. Network size determined how many faces could be accurately recognized as familiar. When the simulated model became sufficiently complex in structure, multiple familiarity traces could be retained in the same network by forming partially-overlapping subnetworks that differ slightly from each other, thereby resulting in a high storage capacity. Fisher's discriminant analysis was applied to identify critical neurons whose spiking activity predicted familiar input patterns. Intriguingly, as sensory exposure was prolonged, the selected critical neurons tended to appear at deeper layers of the network model, suggesting recruitment of additional circuits in the network for incremental information storage. We conclude that generic cortical microcircuits with bidirectional synaptic plasticity have an intrinsic ability to detect familiar inputs. This ability does not require a specialized wiring diagram or supervision and can therefore be expected to emerge naturally in developing cortical circuits.

Bidirectional neural interface: Closed-loop feedback control for hybrid neural systems.

Science.gov (United States)

Chou, Zane; Lim, Jeffrey; Brown, Sophie; Keller, Melissa; Bugbee, Joseph; Broccard, Frédéric D; Khraiche, Massoud L; Silva, Gabriel A; Cauwenberghs, Gert

2015-01-01

Closed-loop neural prostheses enable bidirectional communication between the biological and artificial components of a hybrid system. However, a major challenge in this field is the limited understanding of how these components, the two separate neural networks, interact with each other. In this paper, we propose an in vitro model of a closed-loop system that allows for easy experimental testing and modification of both biological and artificial network parameters. The interface closes the system loop in real time by stimulating each network based on recorded activity of the other network, within preset parameters. As a proof of concept we demonstrate that the bidirectional interface is able to establish and control network properties, such as synchrony, in a hybrid system of two neural networks more significantly more effectively than the same system without the interface or with unidirectional alternatives. This success holds promise for the application of closed-loop systems in neural prostheses, brain-machine interfaces, and drug testing.

Bidirectional ventricular tachycardia of unknown etiology

International Nuclear Information System (INIS)

Ali, M.; Khan, J.A.; Masood, T.; Shamsi, F.; Dero, M.H.; Khan, S.

2013-01-01

A 45 years old male presented to the emergency department with palpitations, headache and apprehension. His electrocardiogram revealed bidirectional ventricular tachycardia. He remained vitally stable and responded to intravenous beta-blocker. Initially digitalis toxicity was suspected but history was negative for digitalis intake. The cause remained unidentified in patient despite detailed investigations. During a short follow-up (of 6 months) he remained asymptomatic and no cause was further identified during this period. Some other unseen causes of bidirectional ventricular tachycardia need to be explored. (author)

Improved broadband and quasi-omnidirectional anti-reflection properties with biomimetic silicon nanostructures.

Science.gov (United States)

Huang, Yi-Fan; Chattopadhyay, Surojit; Jen, Yi-Jun; Peng, Cheng-Yu; Liu, Tze-An; Hsu, Yu-Kuei; Pan, Ci-Ling; Lo, Hung-Chun; Hsu, Chih-Hsun; Chang, Yuan-Huei; Lee, Chih-Shan; Chen, Kuei-Hsien; Chen, Li-Chyong

2007-12-01

Nature routinely produces nanostructured surfaces with useful properties, such as the self-cleaning lotus leaf, the colour of the butterfly wing, the photoreceptor in brittlestar and the anti-reflection observed in the moth eye. Scientists and engineers have been able to mimic some of these natural structures in the laboratory and in real-world applications. Here, we report a simple aperiodic array of silicon nanotips on a 6-inch wafer with a sub-wavelength structure that can suppress the reflection of light at a range of wavelengths from the ultraviolet, through the visible part of the spectrum, to the terahertz region. Reflection is suppressed for a wide range of angles of incidence and for both s- and p-polarized light. The antireflection properties of the silicon result from changes in the refractive index caused by variations in the height of the silicon nanotips, and can be simulated with models that have been used to explain the low reflection from moth eyes. The improved anti-reflection properties of the surfaces could have applications in renewable energy and electro-optical devices for the military.

A LAI inversion algorithm based on the unified model of canopy bidirectional reflectance distribution function for the Heihe River Basin

Science.gov (United States)

Ma, B.; Li, J.; Fan, W.; Ren, H.; Xu, X.

2017-12-01

Leaf area index (LAI) is one of the important parameters of vegetation canopy structure, which can represent the growth condition of vegetation effectively. The accuracy, availability and timeliness of LAI data can be improved greatly, which is of great importance to vegetation-related research, such as the study of atmospheric, land surface and hydrological processes to obtain LAI by remote sensing method. Heihe River Basin is the inland river basin in northwest China. There are various types of vegetation and all kinds of terrain conditions in the basin, so it is helpful for testing the accuracy of the model under the complex surface and evaluating the correctness of the model to study LAI in this area. On the other hand, located in west arid area of China, the ecological environment of Heihe Basin is fragile, LAI is an important parameter to represent the vegetation growth condition, and can help us understand the status of vegetation in the Heihe River Basin. Different from the previous LAI inversion models, the BRDF (bidirectional reflectance distribution function) unified model can be applied for both continuous vegetation and discrete vegetation, it is appropriate to the complex vegetation distribution. LAI is the key input parameter of the model. We establish the inversion algorithm that can exactly retrieve LAI using remote sensing image based on the unified model. First, we determine the vegetation type through the vegetation classification map to obtain the corresponding G function, leaf and surface reflectivity. Then, we need to determine the leaf area index (LAI), the aggregation index (ζ) and the sky scattered light ratio (β) range and the value of the interval, entering all the parameters into the model to calculate the corresponding reflectivity ρ and establish the lookup table of different vegetation. Finally, we can invert LAI on the basis of the established lookup table. The principle of inversion is least squares method. We have produced 1 km

Evaluation of BRDF Archetypes for Representing Surface Reflectance Anisotropy Using MODIS BRDF Data

OpenAIRE

Zhang, Hu; Jiao, Ziti; Dong, Yadong; Li, Xiaowen

2015-01-01

Bidirectional reflectance distribution function (BRDF) archetypes extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo product over the global Earth Observing System Land Validation Core Sites can be used to simplify BRDF models. The present study attempts to evaluate the representativeness of BRDF archetypes for surface reflectance anisotropy. Five-year forward-modeled MODIS multi-angular reflectance (MCD-ref) and aditional actual MODIS multi-angular observat...

Self-oscillating Galvanic Isolated Bidirectional Very High Frequency DC-DC Converter

DEFF Research Database (Denmark)

Pedersen, Jeppe Arnsdorf; Madsen, Mickey Pierre; Knott, Arnold

2015-01-01

This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has to be synch......This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has...

Bidirectional reachability-based modules

CSIR Research Space (South Africa)

Nortje, R

2011-07-01

Full Text Available The authors introduce an algorithm for MinA extraction in EL based on bidirectional reachability. They obtain a significant reduction in the size of modules extracted at almost no additional cost to that of extracting standard reachability...

ultrasound reflecting the morphological properties in soft tissue

DEFF Research Database (Denmark)

Lorentzen, Torben; Larsen, Torben; Court-Payen, Michel

2014-01-01

Ultrasound (US) is an image modality providing the examiner with real-time images which reflect the morphological properties in soft tissue. Different types of transducers are used for different kind of exams. US is cheap, fast, and safe. US is widely used in abdominal imaging including obstetrics...

A Multi-Wavelength Thermal Infrared and Reflectance Scene Simulation Model

Science.gov (United States)

Ballard, J. R., Jr.; Smith, J. A.; Smith, David E. (Technical Monitor)

2002-01-01

Several theoretical calculations are presented and our approach discussed for simulating overall composite scene thermal infrared exitance and canopy bidirectional reflectance of a forest canopy. Calculations are performed for selected wavelength bands of the DOE Multispectral Thermal Imagery and comparisons with atmospherically corrected MTI imagery are underway. NASA EO-1 Hyperion observations also are available and the favorable comparison of our reflective model results with these data are reported elsewhere.

Assessment of biases in MODIS surface reflectance due to Lambertian approximation

Energy Technology Data Exchange (ETDEWEB)

Cook, Robert B [ORNL; SanthanaVannan, Suresh K [ORNL

2010-08-01

Using MODIS data and the AERONET-based Surface Reflectance Validation Network (ASRVN), this work studies errors of MODIS atmospheric correction caused by the Lambertian approximation. On one hand, this approximation greatly simplifies the radiative transfer model, reduces the size of the look-up tables, and makes operational algorithm faster. On the other hand, uncompensated atmospheric scattering caused by Lambertian model systematically biases the results. For example, for a typical bowl-shaped bidirectional reflectance distribution function (BRDF), the derived reflectance is underestimated at high solar or view zenith angles, where BRDF is high, and is overestimated at low zenith angles where BRDF is low. The magnitude of biases grows with the amount of scattering in the atmosphere, i.e., at shorter wavelengths and at higher aerosol concentration. The slope of regression of Lambertian surface reflectance vs. ASRVN bidirectional reflectance factor (BRF) is about 0.85 in the red and 0.6 in the green bands. This error propagates into the MODIS BRDF/albedo algorithm, slightly reducing the magnitude of overall reflectance and anisotropy of BRDF. This results in a small negative bias of spectral surface albedo. An assessment for the GSFC (Greenbelt, USA) validation site shows the albedo reduction by 0.004 in the near infrared, 0.005 in the red, and 0.008 in the green MODIS bands.

On exponential stability of bidirectional associative memory neural networks with time-varying delays

International Nuclear Information System (INIS)

Park, Ju H.; Lee, S.M.; Kwon, O.M.

2009-01-01

For bidirectional associate memory neural networks with time-varying delays, the problems of determining the exponential stability and estimating the exponential convergence rate are investigated by employing the Lyapunov functional method and linear matrix inequality (LMI) technique. A novel criterion for the stability, which give information on the delay-dependent property, is derived. A numerical example is given to demonstrate the effectiveness of the obtained results.

Analytical investigation of bidirectional ductile diaphragms in multi-span bridges

Science.gov (United States)

Wei, Xiaone; Bruneau, Michel

2018-04-01

In the AASHTO Guide Specifications for Seismic Bridge Design Provisions, ductile diaphragms are identified as Permissible Earthquake-Resisting Elements (EREs), designed to help resist seismic loads applied in the transverse direction of bridges. When adding longitudinal ductile diaphragms, a bidirectional ductile diaphragm system is created that can address seismic excitations acting along both the bridge's longitudinal and transverse axes. This paper investigates bidirectional ductile diaphragms with Buckling Restrained Braces (BRBs) in straight multi-span bridge with simply supported floating spans. The flexibility of the substructures in the transverse and longitudinal direction of the bridge is considered. Design procedures for the bidirectional ductile diaphragms are first proposed. An analytical model of the example bridge with bidirectional ductile diaphragms, designed based on the proposed methodology, is then built in SAP2000. Pushover and nonlinear time history analyses are performed on the bridge model, and corresponding results are presented. The effect of changing the longitudinal stiffness of the bidirectional ductile diaphragms in the end spans connecting to the abutment is also investigated, in order to better understand the impact on the bridge's dynamic performance.

Piezoelectric power converter with bi-directional power transfer

DEFF Research Database (Denmark)

2014-01-01

The present invention relates to a bi-directional piezoelectric power converter com¬ prising a piezoelectric transformer. The piezoelectric transformer comprises an input electrode electrically coupled to a primary section of the piezoelectric transformer and an output electrode electrically...... coupled to an output section of the piezoelectric transformer to provide a transformer output signal. A bi-directional switching circuit is coupled between the output electrode and a DC or AC output voltage of the power converter. Forward and reverse current conducting periods of the bi......, a reverse current is conducted through the bi-directional switching circuit from the DC or AC output voltage to the output electrode to discharge the DC or AC output voltage and return power to the primary section of the piezoelectric transformer....

The existence of generalized synchronisation of three bidirectionally coupled chaotic systems

International Nuclear Information System (INIS)

Ai-Hua, Hu; Zhen-Yuan, Xu; Liu-Xiao, Guo

2010-01-01

The existence of two types of generalized synchronisation is studied. The model considered here includes three bidirectionally coupled chaotic systems, and two of them denote the driving systems, while the rest stands for the response system. Under certain conditions, the existence of generalised synchronisation can be turned to a problem of compression fixed point in the family of Lipschitz functions. In addition, theoretical proofs are proposed to the exponential attractive property of generalised synchronisation manifold. Numerical simulations validate the theory. (general)

Observations of a bi-directional lightning leader producing an M-component

Science.gov (United States)

Kotovsky, D. A.; Uman, M. A.; Wilkes, R.; Carvalho, F. L.; Jordan, D. M.

2017-12-01

Lightning discharges to ground often exhibit millisecond-scale surges in the continuing currents following return strokes, called M-components. Relatively little is known regarding the source of M-component charge and the mechanisms by which that charge is transferred to ground. In this work, we seek to directly address these questions by presenting correlated high-speed video and Lightning Mapping Array (LMA) observations of a bi-directional leader that resulted in an M-component occurring in a rocket-and-wire triggered lightning flash. The observed leader initiated in the decayed remnants of a positive leader channel that had traversed virgin air approximately 90 msec prior. Three-dimensional locations and speeds of the photographed bi-directional leader and M-component processes are calculated by mapping video images to the observed LMA channel geometry. Both ends of the bi-directional leader exhibited speeds on the order of 2 x106 m sec-1 over 570 meters of the visible channel. Propagation of the luminosity wave from the in-cloud leader to ground ( 8.8 km channel length) exhibited appreciable dispersion, with rise-times (10-90%) increasing from 330 to 410 μsec and pulse-widths (half-maximum) increasing from 380 to 810 μsec - the M-component current pulse measured at ground-level exhibited a rise-time of 290 μsec and a pulse-width of 770 μsec. Group velocities of the luminosity wave have been calculated as a function of frequency, increasing from 2 x107 to 6 x107 m sec-1 over the dominant signal bandwidth (DC to 2 kHz). Additionally, multiple waves of luminosity are observed within the in-cloud channel, indicating nuanced wave phenomena possibly associated with reflection from the end of the leader channel and attachment with the main lightning channel carrying continuing current to ground.

Integrable hydrodynamics of Calogero-Sutherland model: bidirectional Benjamin-Ono equation

International Nuclear Information System (INIS)

Abanov, Alexander G; Bettelheim, Eldad; Wiegmann, Paul

2009-01-01

We develop a hydrodynamic description of the classical Calogero-Sutherland liquid: a Calogero-Sutherland model with an infinite number of particles and a non-vanishing density of particles. The hydrodynamic equations, being written for the density and velocity fields of the liquid, are shown to be a bidirectional analog of the Benjamin-Ono equation. The latter is known to describe internal waves of deep stratified fluids. We show that the bidirectional Benjamin-Ono equation appears as a real reduction of the modified KP hierarchy. We derive the chiral nonlinear equation which appears as a chiral reduction of the bidirectional equation. The conventional Benjamin-Ono equation is a degeneration of the chiral nonlinear equation at large density. We construct multi-phase solutions of the bidirectional Benjamin-Ono equations and of the chiral nonlinear equations

Salinity and spectral reflectance of soils

Science.gov (United States)

Szilagyi, A.; Baumgardner, M. F.

1991-01-01

The basic spectral response related to the salt content of soils in the visible and reflective IR wavelengths is analyzed in order to explore remote sensing applications for monitoring processes of the earth system. The bidirectional reflectance factor (BRF) was determined at 10 nm of increments over the 520-2320-nm spectral range. The effect of salts on reflectance was analyzed on the basis of 162 spectral measurements. MSS and TM bands were simulated within the measured spectral region. A strong relationship was found in variations of reflectance and soil characteristics pertaining to salinization and desalinization. Although the individual MSS bands had high R-squared values and 75-79 percent of soil/treatment combinations were separable, there was a large number of soil/treatment combinations not distinguished by any of the four highly correlated MSS bands under consideration.

Pore-level determination of spectral reflection behaviors of high-porosity metal foam sheets

Science.gov (United States)

Li, Yang; Xia, Xin-Lin; Ai, Qing; Sun, Chuang; Tan, He-Ping

2018-03-01

Open cell metal foams are currently attracting attention and their radiative behaviors are of primary importance in high temperature applications. The spectral reflection behaviors of high-porosity metal foam sheets, bidirectional reflectance distribution function (BRDF) and directional-hemispherical reflectivity were numerically investigated. A set of realistic nickel foams with porosity from 0.87 to 0.97 and pore density from 10 to 40 pores per inch were tomographied to obtain their 3-D digital cell network. A Monte Carlo ray-tracing method was employed in order to compute the pore-level radiative transfer inside the network within the limit of geometrical optics. The apparent reflection behaviors and their dependency on the textural parameters and strut optical properties were comprehensively computed and analysed. The results show a backward scattering of the reflected energy at the foam sheet surface. Except in the cases of large incident angles, an energy peak is located almost along the incident direction and increases with increasing incident angles. Through an analytical relation established, the directional-hemispherical reflectivity can be related directly to the porosity of the foam sheet and to the complex refractive index of the solid phase as well as the specularity parameter which characterizes the local reflection model. The computations show that a linear decrease in normal-hemispherical reflectivity occurs with increasing porosity. The rate of this decrease is directly proportional to the strut normal reflectivity. In addition, the hemispherical reflectivity increases as a power function of the incident angle cosine.

Remote sensing reflectance and inherent optical properties of oceanic waters derived from above-water measurements

Science.gov (United States)

Lee, Zhongping; Carder, Kendall L.; Steward, Robert G.; Peacock, Thomas G.; Davis, Curtiss O.; Mueller, James L.

1997-02-01

Remote-sensing reflectance and inherent optical properties of oceanic properties of oceanic waters are important parameters for ocean optics. Due to surface reflectance, Rrs or water-leaving radiance is difficult to measure from above the surface. It usually is derived by correcting for the reflected skylight in the measured above-water upwelling radiance using a theoretical Fresnel reflectance value. As it is difficult to determine the reflected skylight, there are errors in the Q and E derived Rrs, and the errors may get bigger for high chl_a coastal waters. For better correction of the reflected skylight,w e propose the following derivation procedure: partition the skylight into Rayleigh and aerosol contributions, remove the Rayleigh contribution using the Fresnel reflectance, and correct the aerosol contribution using an optimization algorithm. During the process, Rrs and in-water inherent optical properties are derived at the same time. For measurements of 45 sites made in the Gulf of Mexico and Arabian Sea with chl_a concentrations ranging from 0.07 to 49 mg/m3, the derived Rrs and inherent optical property values were compared with those from in-water measurements. These results indicate that for the waters studied, the proposed algorithm performs quite well in deriving Rrs and in- water inherent optical properties from above-surface measurements for clear and turbid waters.

Symmetry evaluation for an interferometric fiber optic gyro coil utilizing a bidirectional distributed polarization measurement system.

Science.gov (United States)

Peng, Feng; Li, Chuang; Yang, Jun; Hou, Chengcheng; Zhang, Haoliang; Yu, Zhangjun; Yuan, Yonggui; Li, Hanyang; Yuan, Libo

2017-07-10

We propose a dual-channel measurement system for evaluating the optical path symmetry of an interferometric fiber optic gyro (IFOG) coil. Utilizing a bidirectional distributed polarization measurement system, the forward and backward transmission performances of an IFOG coil are characterized simultaneously by just a one-time measurement. The simple but practical configuration is composed of a bidirectional Mach-Zehnder interferometer and multichannel transmission devices connected to the IFOG coil under test. The static and dynamic temperature results of the IFOG coil reveal that its polarization-related symmetric properties can be effectively obtained with high accuracy. The optical path symmetry investigation is highly beneficial in monitoring and improving the winding technology of an IFOG coil and reducing the nonreciprocal effect of an IFOG.

Properties Of Reflection Holograms Recorded In Polaroid's DMP-128 Photopolymer

Science.gov (United States)

Ingwall, R. T.; Troll, M.; Vetterling, W. T.

1987-06-01

Optical and microstructural properties of reflection holograms recorded in DMP-128 are reported. The optical properties are determined from transmission spectra of the holograms by ignoring the relatively small effects of light scattering and absorption. Microstructure is revealed by light and electron microscopic examination of hologram sections prepared either by diamond grit abrasion or by freeze fracture. Fringe planes are clearly seen with both sectioning procedures. The spacing between adjacent planes is strongly affected by processing conditions. Standard processing produces reflection holograms with fringe plane spacing that decreases continuously from the film:substrate interface to the film:air interface. These holograms have wide spectral bandwidths (100-200nm) and irregular band shapes. Narrow bandwidth holograms are produced from slightly more complicated processing steps. The optical properties of both types of holograms are compared to a theoretical model developed to account for nonuniform fringe plane spacing. Important experimental features such as spectral bandwidth and diffraction efficiency are readily explained by the theory and the observed microstructure.

A Method of Retrieving BRDF from Surface-Reflected Radiance Using Decoupling of Atmospheric Radiative Transfer and Surface Reflection

Directory of Open Access Journals (Sweden)

Alexander Radkevich

2018-04-01

Full Text Available Bi-directional reflection distribution function (BRDF defines anisotropy of the surface reflection. It is required to specify the boundary condition for radiative transfer (RT modeling used in aerosol retrievals, cloud retrievals, atmospheric modeling, and other applications. Ground based measurements of reflected radiance draw increasing attention as a source of information about anisotropy of surface reflection. Derivation of BRDF from surface radiance requires atmospheric correction. This study develops a new method of retrieving BRDF on its whole domain, making it immediately suitable for further atmospheric RT modeling applications. The method is based on the integral equation relating surface-reflected radiance, BRDF, and solutions of two auxiliary atmosphere-only RT problems. The method requires kernel-based BRDF. The weights of the kernels are obtained with a quickly converging iterative procedure. RT modeling has to be done only one time before the start of iterative process.

The Effect of Non-Lambertian Surface Reflectance on Aerosol Radiative Forcing

Energy Technology Data Exchange (ETDEWEB)

Ricchiazzi, P.; O' Hirok, W.; Gautier, C.

2005-03-18

Surface reflectance is an important factor in determining the strength of aerosol radiative forcing. Previous studies of radiative forcing assumed that the reflected surface radiance is isotropic and does not depend on incident illumination angle. This Lambertian reflection model is not a very good descriptor of reflectance from real land and ocean surfaces. In this study we present computational results for the seasonal average of short and long wave aerosol radiative forcing at the top of the atmosphere and at the surface. The effect of the Lambertian assumption is found through comparison with calculations using a more detailed bi-direction reflectance distribution function (BRDF).

Influence of Aerosols And Surface Reflectance On NO2 Retrieval Over China From 2005 to 2015

Science.gov (United States)

Liu, M.; Lin, J.

2016-12-01

Satellite observation is a powerful way to analysis annual and seasonal variations of nitrogen dioxide (NO2). However, much retrieval of vertical column densities (VCDs) of normally do not explicitly account for aerosol optical effects and surface reflectance anisotropy that vary with space and time. In traditional retrieval, aerosols' effects are often considered as cloud. However, China has complicated aerosols type and aerosol loading. Their optical properties may be very different from the cloud. Furthermore, China has undergone big changes in land use type in recent 10 years. Traditional climatology surface reflectance data may not have representation. In order to study spatial-temporal variation of and influences of these two factors on variations and trends, we use an improved retrieval method of VCDs over China, called the POMINO, based on measurements from the Ozone Monitoring Instrument (OMI), and we compare the results of without aerosol, without surface reflectance treatments and without both to the original POMINO product from 2005 to 2015. Furthermore, we will study correspondent spatial-temporal variations of aerosols, represented by MODIS aerosol optical depth (AOD) data and CALIOP extinction data; surface reflectance, represented by MODIS bidirectional reflectance distribution function (BRDF) data.

A high-damping magnetorheological elastomer with bi-directional magnetic-control modulus for potential application in seismology

Energy Technology Data Exchange (ETDEWEB)

Yu, Miao, E-mail: yumiao@cqu.edu.cn; Qi, Song; Fu, Jie; Zhu, Mi [Key Lab for Optoelectronic Technology and Systems, Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

2015-09-14

A high-damping magnetorheological elastomer (MRE) with bi-directional magnetic-control modulus is developed. This MRE was synthesized by filling NdFeB particles into polyurethane (PU)/ epoxy (EP) interpenetrating network (IPN) structure. The anisotropic samples were prepared in a permanent magnetic field and magnetized in an electromagnetic field of 1 T. Dynamic mechanical responses of the MRE to applied magnetic fields are investigated through magneto-rheometer, and morphology of MREs is observed via scanning electron microscope (SEM). Test result indicates that when the test field orientation is parallel to that of the sample's magnetization, the shear modulus of sample increases. On the other hand, when the orientation is opposite to that of the sample's magnetization, shear modulus decreases. In addition, this PU/EP IPN matrix based MRE has a high-damping property, with high loss factor and can be controlled by applying magnetic field. It is expected that the high damping property and the ability of bi-directional magnetic-control modulus of this MRE offer promising advantages in seismologic application.

The Topologies Research of a Soft Switching Bidirectional DC/DC Converter

DEFF Research Database (Denmark)

Zhang, Qi; Zhang, Yongping; Sun, Xiangdong

2017-01-01

A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....

Adjustment of Sentinel-2 Multi-Spectral Instrument (MSI) Red-Edge Band Reflectance to Nadir BRDF Adjusted Reflectance (NBAR) and Quantification of Red-Edge Band BRDF Effects

OpenAIRE

David P. Roy; Zhongbin Li; Hankui K. Zhang

2017-01-01

Optical wavelength satellite data have directional reflectance effects over non-Lambertian surfaces, described by the bidirectional reflectance distribution function (BRDF). The Sentinel-2 multi-spectral instrument (MSI) acquires data over a 20.6° field of view that have been shown to have non-negligible BRDF effects in the visible, near-infrared, and short wave infrared bands. MSI red-edge BRDF effects have not been investigated. In this study, they are quantified by an examination of 6.6 mi...

Scaling properties of optical reflectance from quasi-periodic superlattices

International Nuclear Information System (INIS)

Wu Xiang; Yao Hesheng; Feng Weiguo

1991-08-01

The scaling properties of the optical reflectance from two types of quasi-periodic metal-insulator superlattices, one with the structure of Cantor bars and the other with the structure of Cantorian-Fibonaccian train, have been studied for the region of s-polarized soft x-rays and extreme ultraviolet. By using the hydrodynamic model of electron dynamics and transfer-matrix method, and be taking into account retardation effects, we have presented the formalism of the reflectivity for the superlattices. From our numerical results, we found that the reflection spectra of the quasi-superlattices have a rich structure of self-similarity. The interesting scaling indices, which are related to the fractal dimensions, of the spectra are also discussed for the two kinds of the quasi-superlattices. (author). 10 refs, 7 figs

Spectral reflectance properties of carbonaceous chondrites: 1. CI chondrites

Science.gov (United States)

Cloutis, E. A.; Hiroi, T.; Gaffey, M. J.; Alexander, C. M. O.'D.; Mann, P.

2011-03-01

Existing reflectance spectra of CI chondrites (18 spectra of 3 CIs) have been augmented with new (18 spectra of 2 CIs) reflectance spectra to ascertain the spectral variability of this meteorite class and provide insights into their spectral properties as a function of grain size, composition, particle packing, and viewing geometry. Particle packing and viewing geometry effects have not previously been examined for CI chondrites. The current analysis is focused on the 0.3-2.5 μm interval, as this region is available for the largest number of CI spectra. Reflectance spectra of powdered CI1 chondrites are uniformly dark (IOM), as no other CI opaque phase appears able to produce concurrent darkening and bluing. Magnetite can also explain the presence of an absorption feature near 1 μm in some CI spectra. The most blue-sloped spectra are generally associated with the larger grain size samples. For incidence and emission angles <60°, increasing phase angle results in darker and redder spectra, particularly below ∼1 μm. At high incidence angles (60°), increasing emission angle results in brighter and redder spectra. More densely packed samples and underdense (fluffed) samples show lower overall reflectance than normally packed and flat-surface powdered samples. Some B-class asteroids exhibit selected spectral properties consistent with CI chondrites, although perfect spectral matches have not been found. Because many CI chondrite spectra exhibit absorption features that can be related to specific mineral phases, the search for CI parent bodies can fruitfully be conducted using such parameters.

1.25 Gbit/s bidirectional link in an access network employing a reconfigurable optical add/drop multiplexer and a reflective semiconductor optical amplifier

NARCIS (Netherlands)

Urban, P.J.; de Laat, M.M.; Klein, E.J.; Koonen, A.M.J.; Khoe, G.D.; de Waardt, H.; Marciniak, M.; Jaworski, M.; Zdabiwicz, M.

2008-01-01

In this paper, we demonstrate symmetrical bidirectional transmission of 1.25 Gbit/s wavelength channels in an access network link employing centralized light generation, colourless optical network unit (ONU) and a reconfigurable optical add/drop multiplexer (ROADM). The architecture of ONU is based

Characterizing Land Surface Anisotropic Reflectance over Rugged Terrain: A Review of Concepts and Recent Developments

Directory of Open Access Journals (Sweden)

Jianguang Wen

2018-02-01

Full Text Available Rugged terrain, including mountains, hills, and some high lands are typical land surfaces around the world. As a physical parameter for characterizing the anisotropic reflectance of the land surface, the importance of the bidirectional reflectance distribution function (BRDF has been gradually recognized in the remote sensing community, and great efforts have been dedicated to build BRDF models over various terrain types. However, on rugged terrain, the topography intensely affects the shape and magnitude of the BRDF and creates challenges in modeling the BRDF. In this paper, after a brief introduction of the theoretical background of the BRDF over rugged terrain, the status of estimating land surface BRDF properties over rugged terrain is comprehensively reviewed from a historical perspective and summarized in two categories: BRDFs describing solo slopes and those describing composite slopes. The discussion focuses on land surface reflectance retrieval over mountainous areas, the difference in solo slope and composite slope BRDF models, and suggested future research to improve the accuracy of BRDFs derived with remote sensing satellites.

A bidirectional shape memory alloy folding actuator

International Nuclear Information System (INIS)

Paik, Jamie K; Wood, Robert J

2012-01-01

This paper presents a low-profile bidirectional folding actuator based on annealed shape memory alloy sheets applicable for meso- and microscale systems. Despite the advantages of shape memory alloys—high strain, silent operation, and mechanical simplicity—their application is often limited to unidirectional operation. We present a bidirectional folding actuator that produces two opposing 180° motions. A laser-patterned nickel alloy (Inconel 600) heater localizes actuation to the folding sections. The actuator has a thin ( < 1 mm) profile, making it appropriate for use in robotic origami. Various design parameters and fabrication variants are described and experimentally explored in the actuator prototype. (paper)

Hemispherical reflectance model for passive images in an outdoor environment.

Science.gov (United States)

Kim, Charles C; Thai, Bea; Yamaoka, Neil; Aboutalib, Omar

2015-05-01

We present a hemispherical reflectance model for simulating passive images in an outdoor environment where illumination is provided by natural sources such as the sun and the clouds. While the bidirectional reflectance distribution function (BRDF) accurately produces radiance from any objects after the illumination, using the BRDF in calculating radiance requires double integration. Replacing the BRDF by hemispherical reflectance under the natural sources transforms the double integration into a multiplication. This reduces both storage space and computation time. We present the formalism for the radiance of the scene using hemispherical reflectance instead of BRDF. This enables us to generate passive images in an outdoor environment taking advantage of the computational and storage efficiencies. We show some examples for illustration.

DRAWING FOR TRAFFIC MARKING USING BIDIRECTIONAL GRADIENT-BASED DETECTION WITH MMS LIDAR INTENSITY

Directory of Open Access Journals (Sweden)

G. Takahashi

2016-06-01

Full Text Available Recently, the development of autonomous cars is accelerating on the integration of highly advanced artificial intelligence, which increases demand for a digital map with high accuracy. In particular, traffic markings are required to be precisely digitized since automatic driving utilizes them for position detection. To draw traffic markings, we benefit from Mobile Mapping Systems (MMS equipped with high-density Laser imaging Detection and Ranging (LiDAR scanners, which produces large amount of data efficiently with XYZ coordination along with reflectance intensity. Digitizing this data, on the other hand, conventionally has been dependent on human operation, which thus suffers from human errors, subjectivity errors, and low reproductivity. We have tackled this problem by means of automatic extraction of traffic marking, which partially accomplished to draw several traffic markings (G. Takahashi et al., 2014. The key idea of the method was extracting lines using the Hough transform strategically focused on changes in local reflection intensity along scan lines. However, it failed to extract traffic markings properly in a densely marked area, especially when local changing points are close each other. In this paper, we propose a bidirectional gradient-based detection method where local changing points are labelled with plus or minus group. Given that each label corresponds to the boundary between traffic markings and background, we can identify traffic markings explicitly, meaning traffic lines are differentiated correctly by the proposed method. As such, our automated method, a highly accurate and non-human-operator-dependent method using bidirectional gradient-based algorithm, can successfully extract traffic lines composed of complex shapes such as a cross walk, resulting in minimizing cost and obtaining highly accurate results.

Drawing for Traffic Marking Using Bidirectional Gradient-Based Detection with MMS LIDAR Intensity

Science.gov (United States)

Takahashi, G.; Takeda, H.; Nakamura, K.

2016-06-01

Recently, the development of autonomous cars is accelerating on the integration of highly advanced artificial intelligence, which increases demand for a digital map with high accuracy. In particular, traffic markings are required to be precisely digitized since automatic driving utilizes them for position detection. To draw traffic markings, we benefit from Mobile Mapping Systems (MMS) equipped with high-density Laser imaging Detection and Ranging (LiDAR) scanners, which produces large amount of data efficiently with XYZ coordination along with reflectance intensity. Digitizing this data, on the other hand, conventionally has been dependent on human operation, which thus suffers from human errors, subjectivity errors, and low reproductivity. We have tackled this problem by means of automatic extraction of traffic marking, which partially accomplished to draw several traffic markings (G. Takahashi et al., 2014). The key idea of the method was extracting lines using the Hough transform strategically focused on changes in local reflection intensity along scan lines. However, it failed to extract traffic markings properly in a densely marked area, especially when local changing points are close each other. In this paper, we propose a bidirectional gradient-based detection method where local changing points are labelled with plus or minus group. Given that each label corresponds to the boundary between traffic markings and background, we can identify traffic markings explicitly, meaning traffic lines are differentiated correctly by the proposed method. As such, our automated method, a highly accurate and non-human-operator-dependent method using bidirectional gradient-based algorithm, can successfully extract traffic lines composed of complex shapes such as a cross walk, resulting in minimizing cost and obtaining highly accurate results.

Bidirectional and simultaneous FTTX/Ethernet services using RSOA based remodulation and polarization multiplexing technique

Science.gov (United States)

Das, Anindya S.; Patra, Ardhendu S.

2015-08-01

A bidirectional and simultaneous transmission of Ethernet, FTTX services through single optical carrier wavelength employing polarization multiplexing technique in the transmitter end and the user end. 10 Gbps and 2.5 Gbps datarates are transmitted over 50 km single mode fiber employing POLMUX technique at OLT and ONU to provide Ethernet and FTTX services concurrently to the user. Reflective semiconductor optical amplifier is used to reuse and remodulate the downlink signal to uplink transmission. The upstream and the downstream transmission performances are observed by the bit error rate values and the eye diagrams obtained by the BER analyzer.

An Operational Scheme for Deriving Standardised Surface Reflectance from Landsat TM/ETM+ and SPOT HRG Imagery for Eastern Australia

Directory of Open Access Journals (Sweden)

Neil Flood

2013-01-01

Full Text Available Operational monitoring of vegetation and land surface change over large areas can make good use of satellite sensors that measure radiance reflected from the Earth’s surface. Monitoring programs use multiple images for complete spatial coverage over time. Accurate retrievals of vegetation cover and vegetation change estimates can be hampered by variation, in both space and time, in the measured radiance, caused by atmospheric conditions, topography, sensor location, and sun elevation. In order to obtain estimates of cover that are comparable between images, and to retrieve accurate estimates of change, these sources of variation must be removed. In this paper we present a preprocessing scheme for minimising atmospheric, topographic and bi-directional reflectance effects on Landsat-5 TM, Landsat-7 ETM+ and SPOT-5 HRG imagery. The approach involves atmospheric correction to compute surface-leaving radiance, and bi-directional reflectance modelling to remove the effects of topography and angular variation in reflectance. The bi-directional reflectance model has been parameterised for eastern Australia, but the general approach is more widely applicable. The result is surface reflectance standardised to a fixed viewing and illumination geometry. The method can be applied to the entire record for these instruments, without intervention, which is of increasing importance with the increased availability of long term image archives. Validation shows that the corrections improve the estimation of reflectance at any given angular configuration, thus allowing the removal from the reflectance signal of much variation due to factors independent of the land surface. The method has been used to process over 45,000 Landsat-5 TM and Landsat-7 ETM+ scenes and 2,500 SPOT-5 scenes, over eastern Australia, and is now in use in operational monitoring programs.

Bidirectional uncompressed HD video distribution over fiber employing VCSELs

DEFF Research Database (Denmark)

Estaran Tolosa, Jose Manuel; Vegas Olmos, Juan José; Rodes, G. A.

2012-01-01

We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links.......We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links....

Filling a gap in multiple scattering theory

NARCIS (Netherlands)

Hovenier, J.W.; Stam, D.M.; Videen, G.; et al,

2007-01-01

Horizontal incidence and reflection by a plane-parallel atmosphere is investigated. A peculiar discontinuity of the reflected intensity is discussed. Several interesting properties of the bidirectional reflection function are presented, together with some applications.

Engineering controllable bidirectional molecular motors based on myosin

Science.gov (United States)

Chen, Lu; Nakamura, Muneaki; Schindler, Tony D.; Parker, David; Bryant, Zev

2012-04-01

Cytoskeletal motors drive the transport of organelles and molecular cargoes within cells and have potential applications in molecular detection and diagnostic devices. Engineering molecular motors with controllable properties will allow selective perturbation of mechanical processes in living cells and provide optimized device components for tasks such as molecular sorting and directed assembly. Biological motors have previously been modified by introducing activation/deactivation switches that respond to metal ions and other signals. Here, we show that myosin motors can be engineered to reversibly change their direction of motion in response to a calcium signal. Building on previous protein engineering studies and guided by a structural model for the redirected power stroke of myosin VI, we have constructed bidirectional myosins through the rigid recombination of structural modules. The performance of the motors was confirmed using gliding filament assays and single fluorophore tracking. Our strategy, in which external signals trigger changes in the geometry and mechanics of myosin lever arms, should make it possible to achieve spatiotemporal control over a range of motor properties including processivity, stride size and branchpoint turning.

Global evaluation of ammonia bidirectional exchange and livestock diurnal variation schemes

Science.gov (United States)

Bidirectional air–surface exchange of ammonia (NH3) has been neglected in many air quality models. In this study, we implement the bidirectional exchange of NH3 in the GEOS-Chem global chemical transport model. We also introduce an updated diurnal variability scheme for NH3...

Bidirectional semantic associations between social power and weight.

Science.gov (United States)

He, Xiaoling; Chen, Jun; Li, Jianan

2018-02-01

Two experiments were conducted to examine bidirectional semantic associations between power and weight using a priming paradigm. Bidirectionality in the relationship between power and weight was demonstrated, utilising tasks that were identical except that the orders in which the stimuli were presented were reversed. In Experiment 1, an empty scale leaning either leftward or rightward was used as a priming stimulus, and a scale that appeared in equilibrium with a pair of power words was used as a target stimulus. In Experiment 2, a scale with a pair of words that appeared in equilibrium was used as a priming stimulus, and an empty scale leaning either leftward or rightward was used as a target stimulus. We identified interaction effects between power and weight in both experiments. Associations between power and weight provide evidence for both conceptual metaphor views and evolutionary theory. The bidirectionality of metaphorical effects is in line with the strong version of metaphoric structuring. Both language and experiential correlations play important roles in the development of the mapping between power and weight. © 2016 International Union of Psychological Science.

Performance and cavitation characteristics of bi-directional hydrofoils

Science.gov (United States)

Nedyalkov, Ivaylo; Wosnik, Martin

2013-11-01

Tidal turbines extract energy from flows which reverse direction. One way to address this bi-directionality in horizontal axis turbines that avoid the use of complex and maintenance-intensive yaw or blade pitch mechanisms, is to design bi-directional blades which perform (equally) well in either flow direction. A large number of proposed hydrofoil designs were investigated using numerical simulations. Selected candidate foils were also tested (at various speeds and angles of attack) in the High-Speed Cavitation Tunnel (HICaT) at the University of New Hampshire. Lift and drag were measured using a force balance, and cavitation inception and desinence were recorded. Experimental and numerical results were compared, and the foils were compared to each other and to reference foils. Bi-directional hydrofoils may provide a feasible solution to the problem of reversing flow direction, when their performance and cavitation characteristics are comparable to those for unidirectional foils, and the penalty in decreased energy production is outweighed by the cost reduction due to lower complexity and respectively lower installation and maintenance costs.

A psychophysically validated metric for bidirectional texture data reduction

Czech Academy of Sciences Publication Activity Database

Filip, Jiří; Chantler, M.J.; Green, P.R.; Haindl, Michal

2008-01-01

Roč. 27, č. 5 (2008), s. 138:1-138:11 ISSN 0730-0301 R&D Projects: GA AV ČR 1ET400750407; GA ČR GA102/08/0593 Institutional research plan: CEZ:AV0Z10750506 Keywords : Bidirectional Texture Functions * texture compression Subject RIV: BD - Theory of Information Impact factor: 3.383, year: 2008 http://library.utia.cas.cz/separaty/2008/RO/haindl-a psychophysically validated metric for bidirectional texture data reduction.pdf

Mechanical properties and fire retardancy of bidirectional reinforced composite based on biodegradable starch resin and basalt fibres

Directory of Open Access Journals (Sweden)

2008-11-01

Full Text Available Environmental problems caused by extensive use of polymeric materials arise mainly due to lack of landfill space and depletion of finite natural resources of fossil raw materials, such as petroleum or natural gas. The substitution of synthetic petroleum-based resins with natural biodegradable resins appears to be one appropriate measure to remedy the above-mentioned situation. This study presents the development of a composite that uses environmentally degradable starch-based resin as matrix and basalt fibre plain fabric as reinforcement. Prepreg sheets were manufactured by means of a modified doctor blade system and a hot power press. The sheets were used to manufacture bidirectional-reinforced specimens with fibre volume contents ranging from 33 to 61%. Specimens were tested for tensile and flexural strength, and exhibited values of up to 373 and 122 MPa, respectively. Through application of silane coupling agents to the reinforcement fibres, the flexural composite properties were subsequently improved by as much as 38%. Finally, in order to enhance the fire retardancy and hence the applicability of the composite, fire retardants were applied to the resin, and their effectiveness was tested by means of flame rating (according to UL 94 and thermogravimetric analysis (TGA, respectively.

Numerical Modelling of a Bidirectional Long Ring Raman Fiber Laser Dynamics

Science.gov (United States)

Sukhanov, S. V.; Melnikov, L. A.; Mazhirina, Yu A.

2017-11-01

The numerical model for the simulation of the dynamics of a bidirectional long ring Raman fiber laser is proposed. The model is based on the transport equations and Courant-Isaacson-Rees method. Different regimes of a bidirectional long ring Raman fiber laser and long time-domain realizations are investigated.

Framewise phoneme classification with bidirectional LSTM and other neural network architectures.

Science.gov (United States)

Graves, Alex; Schmidhuber, Jürgen

2005-01-01

In this paper, we present bidirectional Long Short Term Memory (LSTM) networks, and a modified, full gradient version of the LSTM learning algorithm. We evaluate Bidirectional LSTM (BLSTM) and several other network architectures on the benchmark task of framewise phoneme classification, using the TIMIT database. Our main findings are that bidirectional networks outperform unidirectional ones, and Long Short Term Memory (LSTM) is much faster and also more accurate than both standard Recurrent Neural Nets (RNNs) and time-windowed Multilayer Perceptrons (MLPs). Our results support the view that contextual information is crucial to speech processing, and suggest that BLSTM is an effective architecture with which to exploit it.

Constrained bidirectional propagation and stroke segmentation

Energy Technology Data Exchange (ETDEWEB)

Mori, S; Gillespie, W; Suen, C Y

1983-03-01

A new method for decomposing a complex figure into its constituent strokes is described. This method, based on constrained bidirectional propagation, is suitable for parallel processing. Examples of its application to the segmentation of Chinese characters are presented. 9 references.

Algorithm of extraction optics properties from the measurement of spatially resolved diffuse reflectance

International Nuclear Information System (INIS)

Cunill Rodriguez, Margarita; Delgado Atencio, Jose Alberto; Castro Ramos, Jorge; Vazquez y Montiel, Sergio

2009-01-01

There are several methods to obtain the optical parameters of biological tissues from the measurement of spatially resolved diffuse reflectance. One of them is well-known as Video Reflectometry in which a camera CCD is used as detection and recording system of the lateral distribution of diffuse reflectance Rd(r) when an infinitely narrow light beam impinges on the tissue. In this paper, we present an algorithm that we have developed for the calibration and application of an experimental set-up of Video Reflectometry destined to extract the optical properties of models of biological tissues with optical properties similar to the human skin. The results of evaluation of the accuracy of the algorithm for optical parameters extraction is shown for a set of proofs reflectance curves with known values of these parameters. In the generation of these curves the simulation of measurement errors was also considered. The results show that it is possible to extract the optical properties with an accuracy error of less than 1% for all the proofs curves. (Author)

High-resolution quantization based on soliton self-frequency shift and spectral compression in a bi-directional comb-fiber architecture

Science.gov (United States)

Zhang, Xuyan; Zhang, Zhiyao; Wang, Shubing; Liang, Dong; Li, Heping; Liu, Yong

2018-03-01

We propose and demonstrate an approach that can achieve high-resolution quantization by employing soliton self-frequency shift and spectral compression. Our approach is based on a bi-directional comb-fiber architecture which is composed of a Sagnac-loop-based mirror and a comb-like combination of N sections of interleaved single-mode fibers and high nonlinear fibers. The Sagnac-loop-based mirror placed at the terminal of a bus line reflects the optical pulses back to the bus line to achieve additional N-stage spectral compression, thus single-stage soliton self-frequency shift (SSFS) and (2 N - 1)-stage spectral compression are realized in the bi-directional scheme. The fiber length in the architecture is numerically optimized, and the proposed quantization scheme is evaluated by both simulation and experiment in the case of N = 2. In the experiment, a quantization resolution of 6.2 bits is obtained, which is 1.2-bit higher than that of its uni-directional counterpart.

Retrieval of optical properties of skin from measurement and modeling the diffuse reflectance

Science.gov (United States)

Douven, Lucien F. A.; Lucassen, Gerald W.

2000-06-01

We present results on the retrieval of skin optical properties obtained by fitting of measurements of the diffuse reflectance of human skin. Reflectance spectra are simulated using an analytical model based on the diffusion approximation. This model is implemented in a simplex fit routine. The skin optical model used consists of five layers representing epidermis, capillary blood plexus, dermis, deep blood plexus and hypodermis. The optical properties of each layer are assumed homogeneously distributed. The main optical absorbers included are melanin in epidermis and blood. The experimental setup consists of a HP photospectrometer equipped with a remote fiber head. Total reflectance spectra were measured in the 400 - 820 nm wavelength range on the volar underarm of 19 volunteers under various conditions influencing the blood content and oxygenation degree. Changes in the reflectance spectra were observed. Using the fit routine changes in blood content in the capillary blood plexus and in the deep blood plexus could be quantified. These showed different influences on the total reflectance. The method can be helpful to quantitatively assess changes in skin color appearance such as occurs in the treatment of port wine stains, blanching, skin irritation and tanning.

Reflection properties of road surfaces. Contribution to OECD Scientific Expert Group AC4 on Road Surface Characteristics.

NARCIS (Netherlands)

Schreuder, D.A.

1983-01-01

Photometric characteristics of road surfaces are dealt with. Representation of reflection properties in public lighting; quality criteria of road lighting installations; classification of road surfaces; the relation between reflection characteristics and other properties of road pavements in public

Outpatient blood pressure monitoring using bi-directional text messaging.

Science.gov (United States)

Anthony, Chris A; Polgreen, Linnea A; Chounramany, James; Foster, Eric D; Goerdt, Christopher J; Miller, Michelle L; Suneja, Manish; Segre, Alberto M; Carter, Barry L; Polgreen, Philip M

2015-05-01

To diagnose hypertension, multiple blood pressure (BP) measurements are recommended. We randomized patients into three groups: EMR-only (patients recorded BP measurements in an electronic medical record [EMR] web portal), EMR + reminders (patients were sent text message reminders to record their BP measurements in the EMR), and bi-directional text messaging (patients were sent a text message asking them to respond with their current BP). Subjects were asked to complete 14 measurements. Automated messages were sent to each patient in the bi-directional text messaging and EMR + reminder groups twice daily. Among 121 patients, those in the bi-directional text messaging group reported the full 14 measurements more often than both the EMR-only group (P text messaging is an effective way to gather patient BP data. Text-message-based reminders alone are an effective way to encourage patients to record BP measurements. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Reflecting and Polarizing Properties of Conductive Fabrics in Ultra-High Frequency Range

Directory of Open Access Journals (Sweden)

Oleg Kiprijanovič

2015-09-01

Full Text Available The system based on ultra-wide band (UWB signals was employed for qualitative estimation of attenuating, reflecting and polarizing properties of conductive fabrics, capable to prevent local static charge accumulation. Pulsed excitation of triangle monopole antenna of 6.5 cm height by rectangular electric pulses induced radiation of UWB signals with spectral density of power having maximum in ultra-high frequency (UHF range. The same antenna was used for the radiated signal receiving. Filters and amplifiers of different passband were employed to divide UHF range into subranges of 0.3-0.55 GHz, 0.55-1 GHz, 1-2 GHz and 2-4 GHz bands. The free space method, when conductive fabric samples of 50x50 cm2 were placed between transmitting and receiving antennas, was used to imitate a practical application. Received wideband signals corresponding to the defined range were detected by unbiased detectors. The fabrics made of two types of warps, containing different threads with conductive yarns, were investigated. It was estimated attenuation and reflective properties of the fabrics when electric field is collinear or perpendicular to thread direction. In the UHF range it was revealed good reflecting properties of the fabrics containing metallic component in the threads. The system has advantages but not without a certain shortcoming. Adapting it for specific tasks should lead to more effective usage, including yet unused properties of the UWB signals.

A programme for bidirectional phonology and phonetics and their acquisition and evolution

NARCIS (Netherlands)

Boersma, P.; Benz, A.; Mattausch, J.

2011-01-01

This paper summarizes an existing bidirectional six-level model of phonology and phonetics (and a bit of morphology). Bidirectionality in this case refers to the modelling of both the speaking process (production) and the listening process (comprehension). The elements of the grammar (the

Microwave reflection measurements of the dielectric properties of concrete : final report.

Science.gov (United States)

1983-01-01

The use of microwave reflection measurements to continuously and nondestructively monitor the hydration of concrete is described. The method relies upon the influence of the free-water content on the dielectric properties of the concrete. Use of the ...

Derivation of Coefficients for the Bidirectional Reflection Distribution Function from AVHRR-data over Europe, under Consideration of the Helmholtz Reciprocity Law

Science.gov (United States)

Billing, H.; Koslowsky, D.

In the AVHRR data of the polar orbiting NOAA Satellites, directional reflectance under a certain view from satellite and a certain illumination by the sun is measured. Due to the nearly sunsynchroneous orbit of the NOAA satellite, each area is seen under different viewing angles in successive days. Only after approximately 9 days, the conditions are again similar. Areas, seen in specular direction, may appear only half as bright, as if seen in antispecular direction. This deviation from a Lambertian reflector is a function of the surface roughness and the degree of coverage with vegetation. The NOAA afternoon satellites drift by half an hour from year to year. Thus even data from the same season, but different years, are seen under different illumination conditions. To derive the bidirectional reflection distribution function in dependence on satellite viewing angle and solar illumination becomes a very complicated procedure. Using the Helmholtz reciprocity principle (HRP), i.e. the symetrie in viewing and illumination, reduces the problem by one dimension. For different bidimensional reflection laws it will be tested, whether they can be formulated to fullfill the HRP. Via regression, the parameters will be deduced for time series of AVHRR data of 10 years from NOAA 11,14,16 and 17. Brdfunctions, suggested by Rao as well as a law, suggested by Ba seem to become unstable for low sun resp. large viewing zenit angles. Only brdfs with 4 coefficients can fit the observed distributions. A nonlinear temporal angular model (NTAM), suggested by Latifovic,Cihlar and Chen, seems to be suitable to describe even the hot spot and the dependence on plant growth. The coefficients of these brdf-function will be derived via regression for monthly series of cloud free data for the European area, where AVHRR data in full resolution are received in Berlin. Using these coefficients, monthly maps of surface roughness are produced for the above area for the time since 1985. Ba, M

Network Coding in the Bidirectional Cross

DEFF Research Database (Denmark)

Ertli, Gergö; Paramanathan, Achuthan; Rein, Stephan Alexander

2013-01-01

This paper presents a detailed performance evaluation of inter-session network coding in wireless meshed networks in terms of throughput and energy consumption. A full analytical model is given for three different communication approaches for the bidirectional cross topology using an IEEE 802.11 ...

A New Bi-Directional Projection Model Based on Pythagorean Uncertain Linguistic Variable

Directory of Open Access Journals (Sweden)

Huidong Wang

2018-04-01

Full Text Available To solve the multi-attribute decision making (MADM problems with Pythagorean uncertain linguistic variable, an extended bi-directional projection method is proposed. First, we utilize the linguistic scale function to convert uncertain linguistic variable and provide a new projection model, subsequently. Then, to depict the bi-directional projection method, the formative vectors of alternatives and ideal alternatives are defined. Furthermore, a comparative analysis with projection model is conducted to show the superiority of bi-directional projection method. Finally, an example of graduate’s job option is given to demonstrate the effectiveness and feasibility of the proposed method.

Model based feasibility study on bidirectional check valves in wave energy converters

DEFF Research Database (Denmark)

Hansen, Anders Hedegaard; Pedersen, Henrik C.; Andersen, Torben Ole

2014-01-01

Discrete fluid power force systems have been proposed as the primary stage for Wave Energy Converters (WEC’s) when converting ocean waves into electricity, this to improve the overall efficiency of wave energy devices. This paper presents a model based feasibility study of using bidirectional check....../Off and bidirectional check valves. Based on the analysis it is found that the energy production may be slightly improved by using bidirectional check valves as compared to on/off valves, due to a decrease in switching losses. Furthermore a reduction in high flow peaks are realised. The downside being increased...

85 km long reach PON system using a reflective SOA-EA modulator and distributed Raman fiber amplification

NARCIS (Netherlands)

Tafur Monroy, I.; Öhman, F.; Yvind, K.; Kjaer, R.; Peucheret, C.; Koonen, A.M.J.; Jeppesen, P.

2006-01-01

We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit.

Engineering controllable bidirectional molecular motors based on myosin

Science.gov (United States)

Chen, Lu; Nakamura, Muneaki; Schindler, Tony D.; Parker, David; Bryant, Zev

2012-01-01

Cytoskeletal motors drive the transport of organelles and molecular cargoes within cells1, and have potential applications in molecular detection and diagnostic devices2,3. Engineering molecular motors with dynamically controllable properties will allow selective perturbation of mechanical processes in living cells, and yield optimized device components for complex tasks such as molecular sorting and directed assembly3. Biological motors have previously been modified by introducing activation/deactivation switches that respond to metal ions4,5 and other signals6. Here we show that myosin motors can be engineered to reversibly change their direction of motion in response to a calcium signal. Building on previous protein engineering studies7–11 and guided by a structural model12 for the redirected power stroke of myosin VI, we constructed bidirectional myosins through the rigid recombination of structural modules. The performance of the motors was confirmed using gliding filament assays and single fluorophore tracking. Our general strategy, in which external signals trigger changes in the geometry and mechanics of myosin lever arms, should enable spatiotemporal control over a range of motor properties including processivity, stride size13, and branchpoint turning14. PMID:22343382

Featurized Bidirectional GAN: Adversarial Defense via Adversarially Learned Semantic Inference

OpenAIRE

Bao, Ruying; Liang, Sihang; Wang, Qingcan

2018-01-01

Deep neural networks have been demonstrated to be vulnerable to adversarial attacks, where small perturbations are intentionally added to the original inputs to fool the classifier. In this paper, we propose a defense method, Featurized Bidirectional Generative Adversarial Networks (FBGAN), to capture the semantic features of the input and filter the non-semantic perturbation. FBGAN is pre-trained on the clean dataset in an unsupervised manner, adversarially learning a bidirectional mapping b...

Bilateral Coordination Strategy of Supply Chain with Bidirectional Option Contracts under Inflation

Directory of Open Access Journals (Sweden)

Nana Wan

2015-01-01

Full Text Available As far as the price increase and the demand contraction caused by inflation are concerned, we establish a Stackelberg game model that incorporates bidirectional option contracts and the effect of inflation and derive the optimal ordering and production policies on a one-period two-stage supply chain composed of one supplier and one retailer. Through using the model of wholesale price contracts as the benchmark, we find that the introduction of bidirectional option contracts can benefit both the supplier and the retailer under inflation scenarios. Based on the conclusions drawn above, we design the bilateral coordination mechanism from the different perspective of two members involved and discuss how bidirectional option contracts should be set to achieve channel coordination under inflation scenarios. Through the sensitivity analysis, we illustrate the effect of inflation on the optimal decision variables and the optimal expected profits of the two parties with bidirectional option contracts.

Determining the influential depth for surface reflectance of sediment by BRDF measurements.

Science.gov (United States)

Zhang, H; Voss, K; Reid, R

2003-10-20

We measure the Bi-directional reflectance distribution function (BRDF) of ooid sand layers with three particle size distributions (0.5-1mm, 0.25-0.5mm and 0.125-0.25mm) and layer thicknesses on a reflecting mirror to determine the influential depth in the optical region at wavelengths of 658 nm (red), 570 nm (green) and 457 nm (blue). The hemispherical reflectance (albedo) was used as an indicator of BRDF changes between different layers. Measurements are carried out on both dry and water wetted grains. The results indicate that for both dry and wet and all size distributions, the influential depth is at most 2mm.

ABOUT HYBRID BIDIRECTIONAL ASSOCIATIVE MEMORY NEURAL NETWORKS WITH DISCRETE DELAYS

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

In this paper, hybrid bidirectional associative memory neural networks with discrete delays is considered. By ingeniously importing real parameters di > 0(i = 1,2,···,n) which can be adjusted, we establish some new sufficient conditions for the dynamical characteristics of hybrid bidirectional associative memory neural networks with discrete delays by the method of variation of parameters and some analysis techniques. Our results generalize and improve the related results in [10,11]. Our work is significant...

Bi-directional electrons in the near-Earth plasma sheet

Directory of Open Access Journals (Sweden)

K. Shiokawa

2003-07-01

Full Text Available We have studied the occurrence characteristics of bi-directional electron pitch angle anisotropy (enhanced flux in field-aligned directions, F^ /F|| > 1.5 at energies of 0.1–30 keV using plasma and magnetic field data from the AMPTE/IRM satellite in the near-Earth plasma sheet. The occurrence rate increases in the tailward direction from XGSM = - 9 RE to - 19 RE . The occurrence rate is also enhanced in the midnight sector, and furthermore, whenever the elevation angle of the magnetic field is large while the magnetic field intensity is small, B ~ 15 nT. From these facts, we conclude that the bi-directional electrons in the central plasma sheet are produced mainly in the vicinity of the neutral sheet and that the contribution from ionospheric electrons is minor. A high occurrence is also found after earthward high-speed ion flows, suggesting Fermi-type field-aligned electron acceleration in the neutral sheet. Occurrence characteristics of bi-directional electrons in the plasma sheet boundary layer are also discussed.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; magnetotail; plasma sheet

On Optimal, Minimal BRDF Sampling for Reflectance Acquisition

DEFF Research Database (Denmark)

Nielsen, Jannik Boll; Jensen, Henrik Wann; Ramamoorthi, Ravi

2015-01-01

The bidirectional reflectance distribution function (BRDF) is critical for rendering, and accurate material representation requires data-driven reflectance models. However, isotropic BRDFs are 3D functions, and measuring the reflectance of a flat sample can require a million incident and outgoing...... direction pairs, making the use of measured BRDFs impractical. In this paper, we address the problem of reconstructing a measured BRDF from a limited number of samples. We present a novel mapping of the BRDF space, allowing for extraction of descriptive principal components from measured databases......, such as the MERL BRDF database. We optimize for the best sampling directions, and explicitly provide the optimal set of incident and outgoing directions in the Rusinkiewicz parameterization for n = {1, 2, 5, 10, 20} samples. Based on the principal components, we describe a method for accurately reconstructing BRDF...

A comparison of reflectance properties on polymer micro-structured functional surface

DEFF Research Database (Denmark)

Regi, Francesco; Li, Dongya; Nielsen, Jannik Boll

In this study, a functional micro-structure surface [1] has been developed as a combination of arrays of micro ridges. The scope of the surface is to achieve specific directional optical properties: that is, under constrained lighting, maximizing the reflectance from a certain viewing direction, ...

SO2 frost - UV-visible reflectivity and Io surface coverage

Science.gov (United States)

Nash, D. B.; Fanale, F. P.; Nelson, R. M.

1980-01-01

The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

Energy-efficient three-phase bidirectional converter for grid-connected storage applications

International Nuclear Information System (INIS)

Colmenar-Santos, Antonio; Linares-Mena, Ana-Rosa; Velázquez, Jesús Fernández; Borge-Diez, David

2016-01-01

Highlights: • Storage control system developed based on AC DC three phase bidirectional converter. • Bidirectional AC DC converter for storage integration into distribution grids. • Efficiencies over 98% for values over 30% of the bidirectional converter rated power. • Sensitivity analysis of the parameters set by the transmission system operator. • Low-cost option for control and integration of new grid-connected storage systems. - Abstract: Grid connected energy storage systems are expected to play an essential role in the development of Smart Grids, providing, among other benefits, ancillary services to power grids. It is therefore crucial to design and develop control and conversion systems that represent the key instrument where intelligence for decision-making is applied, in order to validate and ensure its optimal operation as part and parcel of the electrical system. The present research describes the design and development of a battery energy storage system based on an AC-DC three-phase bidirectional converter capable of operating either in charge mode to store electrical energy, or in discharge mode to supply load demands. The design is modelled with MATLAB® Simulink® environment in order to evaluate the performance during load variations. Moreover, the assessment is complemented by a global sensitivity analysis for variations in the operating parameters set by the transmission system operator. The effectiveness of the simulation is confirmed by implementing the system and carrying out grid connection tests, obtaining efficiencies over 98% for values over the 30% of the bidirectional converter rated power.

Andreev reflection properties in a parallel mesoscopic circuit with Majorana bound states

Energy Technology Data Exchange (ETDEWEB)

Mu, Jin-Tao; Han, Yu [Physics Department, Liaoning University, Shenyang 110036 (China); Gong, Wei-Jiang, E-mail: gwj@mail.neu.edu.cn [College of Sciences, Northeastern University, Shenyang 110819 (China)

2017-03-15

We investigate the Andreev reflection in a parallel mesoscopic circuit with Majorana bound states (MBSs). It is found that in such a structure, the Andreev current can be manipulated in a highly efficient way, by the adjustment of bias voltage, dot levels, inter-MBS coupling, and the applied magnetic flux. Besides, the dot-MBS coupling manner is an important factor to modulate the Andreev current, because it influences the period of the conductance oscillation. By discussing the underlying quantum interference mechanism, the Andreev-reflection property is explained in detail. We believe that all the results can assist to understand the nontrivial role of the MBSs in driving the Andreev reflection.

Properties of light reflected from road signs in active imaging for driving safety

Science.gov (United States)

Halstuch, Aviran; Yitzhaky, Yitzhak

2007-10-01

Night-vision systems in vehicles are a new emerging technology. A crucial problem in active (illumination-based) systems is distortion of images by saturation and blooming, due to strong retro-reflections from road signs. In this work we quantified this phenomenon. We measured the Mueller matrices and the polarization state of the reflected light from three different types of road signs commonly used. Measurements of the reflected intensity were taken also with respect to the angle of reflection. We found that different types of signs have different reflection properties. It is concluded from our measurements that the optimal solution for attenuating the retro-reflected intensity is using a linear horizontal polarized light source and a linear vertical polarizer. Unfortunately, while the performance of this solution is good for two types of road signs, it is less efficient for the third sign type.

Studies of dust grain properties in infrared reflection nebulae.

Science.gov (United States)

Pendleton, Y J; Tielens, A G; Werner, M W

1990-01-20

We have developed a model for reflection nebulae around luminous infrared sources embedded in dense dust clouds. The aim of this study is to determine the sizes of the scattering grains. In our analysis, we have adopted an MRN-like power-law size distribution (Mathis, Rumpl, and Nordsieck) of graphite and silicate grains, but other current dust models would give results which were substantially the same. In the optically thin limit, the intensity of the scattered light is proportional to the dust column density, while in the optically thick limit, it reflects the grain albedo. The results show that the shape of the infrared spectrum is the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of our model results with infrared observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse interstellar medium, or one consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains (approximately 5000 angstroms). By adding water ice mantles to the silicate and graphite cores, we have modeled the 3.08 micrometers ice band feature, which has been observed in the spectra of several infrared reflection nebulae. We show that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains. We show that the shape of the ice band is diagnostic of the presence of large grains, as previously suggested by Knacke and McCorkle. Comparison with observations of the BN/KL reflection nebula in the OMC-1 cloud shows that large ice grains (approximately 5000 angstroms) contribute substantially to the scattered light.

Analysis of bi-directional piezoelectric-based converters for zero-voltage switching operation

DEFF Research Database (Denmark)

Ekhtiari, Marzieh; Zhang, Zhe; Andersen, Michael A. E.

2016-01-01

This paper deals with a thorough analysis of zerovoltage switching especially for bi-directional, inductorless, piezoelectric transformer-based switch-mode power supplies with a half-bridge topology. Practically, obtaining zero-voltage switching for all of the switches in a bi-directional piezoel......This paper deals with a thorough analysis of zerovoltage switching especially for bi-directional, inductorless, piezoelectric transformer-based switch-mode power supplies with a half-bridge topology. Practically, obtaining zero-voltage switching for all of the switches in a bi......-directional piezoelectric power converter is a difficult task. However, the analysis in this work will be convenient for overcoming this challenge. The analysis defines the zero-voltage region indicating the operating points whether or not soft switching can be met over the switching frequency and load range. For the first...... time, a comprehensive analysis is provided, which can be used as a design guideline for applying control techniques in order to drive switches in piezoelectric transformer-based converters. This study further conveys the proposed method to the region where all the switches can obtain soft switching...

Photopolarimetric properties of leaf and vegetation covers over a wide range of measurement directions

Science.gov (United States)

Sun, Zhongqiu; Peng, Zhiyan; Wu, Di; Lv, Yunfeng

2018-02-01

The optical scattering property of the target is the essential signal for passive remote sensing applications. To deepen our understanding of the light reflected from vegetation, we present results of photopolarimetric laboratory measurements from single leaf and two vegetation covers (planophile and erectophile) over a wide range of viewing directions. The bidirectional polarized reflectance factor (BPRF) was used to characterize the polarization property of our samples. We observed positive and negative polarization (-BPRFQ) of all samples in the forward scattering and backward scattering directions, respectively. Based on the comparison of the BPRF among single leaf, planophile vegetation and erectophile vegetation, our measurements demonstrate that the orientation of the leaf is a key factor in describing the amount of polarization in the forward scattering direction. Our measurements also validated certain model results stating that (1) specular reflection generates a portion of polarization in the forward scattering direction and diffuses scattering of polarized light in all hemisphere directions, (2) BPRFU is anti-symmetric in the principal plane from a recent study in which the authors simulated the polarized reflectance of vegetation cover using the vector radiative transfer theory. These photopolarimetric measurement results, which can be completely explained by the theoretical results, are useful in remote sensing applications to vegetation.

Bidirectional communication in an HF hybrid organic/solution-processed metal-oxide RFID tag

NARCIS (Netherlands)

Myny, K.; Rockelé, M.; Chasin, A.; Pham, D.V.; Steiger, J.; Botnaras, S.; Weber, D.; Herold, B.; Ficker, J.; Van Putten, B.D.; Gelinck, G.H.; Genoe, J.; Dehaene, W.; Heremans, P.

2014-01-01

A bidirectional communication protocol allows radio-frequency identification (RFID) tags to have readout of multiple tags in the RF field without collision of data. In this paper, we realized bidirectional communication between a reader system and thin-film RFID tag by introducing a novel protocol

Uncertainties in the Bidirectional Biodiesel Supply Chain

NARCIS (Netherlands)

Bot, Pieter; van Donk, Dirk Pieter; Pennink, Bartjan; Simatupang, Togar M.

2015-01-01

For remote areas, small-scale local biodiesel production is particularly attractive if producers and consumers are the same. Such supply chains are labeled as bidirectional. However, little is known on how raw material supply, transportation, logistics, production and operations uncertainties impact

On Training Bi-directional Neural Network Language Model with Noise Contrastive Estimation

OpenAIRE

He, Tianxing; Zhang, Yu; Droppo, Jasha; Yu, Kai

2016-01-01

We propose to train bi-directional neural network language model(NNLM) with noise contrastive estimation(NCE). Experiments are conducted on a rescore task on the PTB data set. It is shown that NCE-trained bi-directional NNLM outperformed the one trained by conventional maximum likelihood training. But still(regretfully), it did not out-perform the baseline uni-directional NNLM.

[Differences of bi-directional regulative effects between acu-moxibustion and Chinese materia medica interventions].

Science.gov (United States)

Cao, Xin; Yu, Zhi; Xu, Bin

2012-10-01

Bi-directional regulation is referred to a balancing effect of both acu-moxibustion and Chinese materia medica interventions when the human body is experiencing a hyperactivity or hypoactivity due to abnormal intrinsic or external factors. In the present paper, the authors analyze their identical and different characteristics from: 1) definition; 2) characters of regulative effects of acu-moxibustion therapy: A) differentiation of meridian and zangfu-organs being the basis of treatment, B) four factors (acupoint-location, body's functional state, acupoint-formula and needle-manipulation techniques) dependant, C) entirety regulation, and D) centrotaxis modulation; 3) characters of Chinese materia medica intervention: including a) correspondence between the drug property and the syndrome being the basis of the regulative effect, b) multi-factors [components (antagonist and agonist), combination, dosages and processing quality of Chinese materia medica, and functional state of the human body] dependant, c) entirety regulation, and d) both centrotaxis and deviation adjustment. In one word, the bi-directional regulation effect is one of the basic characteristics of both acu-moxibustion and Chinese materia medica in clinical practice, but their basis and modes for inducing effects are different.

Retrieving background surface reflectance of Himawari-8/AHI using BRDF modeling

Science.gov (United States)

Choi, Sungwon; Seo, Minji; Lee, Kyeong-sang; Han, Kyung-soo

2017-04-01

In these days, remote sensing is more important than past. And retrieving surface reflectance in remote sensing is also important. So there are many ways to retrieve surface reflectance by my countries with polar orbit and geostationary satellite. We studied Bidirectional Reflectance Distribution Function (BRDF) which is used to retrieve surface reflectance. In BRDF equation, we calculate surface reflectance using BRD components and angular data. BRD components are to calculate 3 of scatterings, isotropic geometric and volumetric scattering. To make Background Surface Reflectance (BSR) of Himawari-8/AHI. We used 5 bands (band1, band2, band3, band4, band5) with BRDF. And we made 5 BSR for 5 channels. For validation, we compare BSR with Top of canopy (TOC) reflectance of AHI. As a result, bias are from -0.00223 to 0.008328 and Root Mean Square Error (RMSE) are from 0.045 to 0.049. We think BSR can be used to replace TOC reflectance in remote sensing to improve weakness of TOC reflectance.

Bidirectional motility of the fission yeast kinesin-5, Cut7

Energy Technology Data Exchange (ETDEWEB)

Edamatsu, Masaki, E-mail: cedam@mail.ecc.u-tokyo.ac.jp

2014-03-28

Highlights: • Motile properties of Cut7 (fission yeast kinesin-5) were studied for the first time. • Half-length Cut7 moved toward plus-end direction of microtubule. • Full-length Cut7 moved toward minus-end direction of microtubule. • N- and C-terminal microtubule binding sites did not switch the motile direction. - Abstract: Kinesin-5 is a homotetrameric motor with its motor domain at the N-terminus. Kinesin-5 crosslinks microtubules and functions in separating spindle poles during mitosis. In this study, the motile properties of Cut7, fission yeast kinesin-5, were examined for the first time. In in vitro motility assays, full-length Cut7 moved toward minus-end of microtubules, but the N-terminal half of Cut7 moved toward the opposite direction. Furthermore, additional truncated constructs lacking the N-terminal or C-terminal regions, but still contained the motor domain, did not switch the motile direction. These indicated that Cut7 was a bidirectional motor, and microtubule binding regions at the N-terminus and C-terminus were not involved in its directionality.

Using Neural Networks to Improve the Performance of Radiative Transfer Modeling Used for Geometry Dependent Surface Lambertian-Equivalent Reflectivity Calculations

Science.gov (United States)

Fasnacht, Zachary; Qin, Wenhan; Haffner, David P.; Loyola, Diego; Joiner, Joanna; Krotkov, Nickolay; Vasilkov, Alexander; Spurr, Robert

2017-01-01

Surface Lambertian-equivalent reflectivity (LER) is important for trace gas retrievals in the direct calculation of cloud fractions and indirect calculation of the air mass factor. Current trace gas retrievals use climatological surface LER's. Surface properties that impact the bidirectional reflectance distribution function (BRDF) as well as varying satellite viewing geometry can be important for retrieval of trace gases. Geometry Dependent LER (GLER) captures these effects with its calculation of sun normalized radiances (I/F) and can be used in current LER algorithms (Vasilkov et al. 2016). Pixel by pixel radiative transfer calculations are computationally expensive for large datasets. Modern satellite missions such as the Tropospheric Monitoring Instrument (TROPOMI) produce very large datasets as they take measurements at much higher spatial and spectral resolutions. Look up table (LUT) interpolation improves the speed of radiative transfer calculations but complexity increases for non-linear functions. Neural networks perform fast calculations and can accurately predict both non-linear and linear functions with little effort.

Implantable neurotechnologies: bidirectional neural interfaces--applications and VLSI circuit implementations.

Science.gov (United States)

Greenwald, Elliot; Masters, Matthew R; Thakor, Nitish V

2016-01-01

A bidirectional neural interface is a device that transfers information into and out of the nervous system. This class of devices has potential to improve treatment and therapy in several patient populations. Progress in very large-scale integration has advanced the design of complex integrated circuits. System-on-chip devices are capable of recording neural electrical activity and altering natural activity with electrical stimulation. Often, these devices include wireless powering and telemetry functions. This review presents the state of the art of bidirectional circuits as applied to neuroprosthetic, neurorepair, and neurotherapeutic systems.

A Novel PPFHB Bidirectional DC-DC Converter for Supercapacitor Application

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.

2009-01-01

This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase-shift modula......This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase...

Bidirectional optimization of the melting spinning process.

Science.gov (United States)

Liang, Xiao; Ding, Yongsheng; Wang, Zidong; Hao, Kuangrong; Hone, Kate; Wang, Huaping

2014-02-01

A bidirectional optimizing approach for the melting spinning process based on an immune-enhanced neural network is proposed. The proposed bidirectional model can not only reveal the internal nonlinear relationship between the process configuration and the quality indices of the fibers as final product, but also provide a tool for engineers to develop new fiber products with expected quality specifications. A neural network is taken as the basis for the bidirectional model, and an immune component is introduced to enlarge the searching scope of the solution field so that the neural network has a larger possibility to find the appropriate and reasonable solution, and the error of prediction can therefore be eliminated. The proposed intelligent model can also help to determine what kind of process configuration should be made in order to produce satisfactory fiber products. To make the proposed model practical to the manufacturing, a software platform is developed. Simulation results show that the proposed model can eliminate the approximation error raised by the neural network-based optimizing model, which is due to the extension of focusing scope by the artificial immune mechanism. Meanwhile, the proposed model with the corresponding software can conduct optimization in two directions, namely, the process optimization and category development, and the corresponding results outperform those with an ordinary neural network-based intelligent model. It is also proved that the proposed model has the potential to act as a valuable tool from which the engineers and decision makers of the spinning process could benefit.

Bidirectional ventricular tachycardia of unusual etiology

Directory of Open Access Journals (Sweden)

Praloy Chakraborty

2015-11-01

Full Text Available Bidirectional ventricular tachycardia (BDVT is a rare form of ventricular arrhythmia, characterized by changing QRS axis of 180 degrees. Digitalis toxicity is considered as commonest cause of BDVT; other causes include aconite toxicity, myocarditis, myocardial infarction, metastatic cardiac tumour and cardiac channelopathies. We describe a case of BDVT in a patient with Anderson-Tawil syndrome.

Bi-directional interhemispheric inhibition during unimanual sustained contractions

Directory of Open Access Journals (Sweden)

Ni Zhen

2009-04-01

Full Text Available Abstract Background The interaction between homologous muscle representations in the right and left primary motor cortex was studied using a paired-pulse transcranial magnetic stimulation (TMS protocol known to evoke interhemispheric inhibition (IHI. The timecourse and magnitude of IHI was studied in fifteen healthy right-handed adults at several interstimulus intervals between the conditioning stimulus and test stimulus (6, 8, 10, 12, 30, 40, 50 ms. IHI was studied in the motor dominant to non-dominant direction and vice versa while the right or left hand was at rest, performing isometric contraction of the first dorsal interosseous (FDI muscle, and isometric contraction of the FDI muscle in the context of holding a pen. Results Compared with rest, IHI was reduced at all ISIs during contraction of either type (with or without the context of pen. IHI was reduced bi-directionally without evidence of hemispheric dominance. Further, contraction of the hand contralateral to the conditioning and test pulse yielded similar reductions in IHI. Conclusion These data provide evidence for bi-directional reduction of IHI during unimanual contractions. During unimanual, sustained contractions of the hand, the contralateral and ipsilateral motor cortices demonstrate reduced inhibition. The data suggest that unimanual movement decreases inhibition bi-directionally across motor hemispheres and offer one explanation for the observation of ipsilateral M1 activity during hand movements.

Family of multiport bidirectional DC-DC converters

NARCIS (Netherlands)

Tao, H.; Kotsopoulos, A.; Duarte, J.L.; Hendrix, M.A.M.

2006-01-01

Multiport DC-DC converters are of potential interest in applications such as generation systems utilising multiple sustainable energy sources. A family of multiport bidirectional DC-DC converters derived from a general topology is presented. The topology shows a combination of DC-link and magnetic

Bi-directional Multi Dimension CAP Transmission for Smart Grid Communication Services

DEFF Research Database (Denmark)

Zhang, Xu; Binti Othman, Maisara; Pang, Xiaodan

2012-01-01

We experimentally demonstrate bi-directional multi dimension carrierless amplitude and phase (CAP) transmission for smart grid communication services based on optical fiber networks. The proposed system is able to support multi-Gb/s transmission with high spectral efficiency.......We experimentally demonstrate bi-directional multi dimension carrierless amplitude and phase (CAP) transmission for smart grid communication services based on optical fiber networks. The proposed system is able to support multi-Gb/s transmission with high spectral efficiency....

Bi-directional magnetic resonance based wireless power transfer for electronic devices

International Nuclear Information System (INIS)

Kar, Durga P.; Nayak, Praveen P.; Bhuyan, Satyanarayan; Mishra, Debasish

2015-01-01

In order to power or charge electronic devices wirelessly, a bi-directional wireless power transfer method has been proposed and experimentally investigated. In the proposed design, two receiving coils are used on both sides of a transmitting coil along its central axis to receive the power wirelessly from the generated magnetic fields through strongly coupled magnetic resonance. It has been observed experimentally that the maximum power transfer occurs at the operating resonant frequency for optimum electric load connected across the receiving coils on both side. The optimum wireless power transfer efficiency is 88% for the bi-directional power transfer technique compared 84% in the one side receiver system. By adopting the developed bi-directional power transfer method, two electronic devices can be powered up or charged simultaneously instead of a single device through usual one side receiver system without affecting the optimum power transfer efficiency

Bi-directional magnetic resonance based wireless power transfer for electronic devices

Energy Technology Data Exchange (ETDEWEB)

Kar, Durga P.; Nayak, Praveen P.; Bhuyan, Satyanarayan; Mishra, Debasish [Department of Electronics and Instrumentation Engineering, Institute of Technical Education and Research, Siksha ‘O’ Anushandhan University, Bhubaneswar 751030 (India)

2015-09-28

In order to power or charge electronic devices wirelessly, a bi-directional wireless power transfer method has been proposed and experimentally investigated. In the proposed design, two receiving coils are used on both sides of a transmitting coil along its central axis to receive the power wirelessly from the generated magnetic fields through strongly coupled magnetic resonance. It has been observed experimentally that the maximum power transfer occurs at the operating resonant frequency for optimum electric load connected across the receiving coils on both side. The optimum wireless power transfer efficiency is 88% for the bi-directional power transfer technique compared 84% in the one side receiver system. By adopting the developed bi-directional power transfer method, two electronic devices can be powered up or charged simultaneously instead of a single device through usual one side receiver system without affecting the optimum power transfer efficiency.

Silent and Efficient Supersonic Bi-Directional Flying Wing

Data.gov (United States)

National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...

Protein Solvent-Accessibility Prediction by a Stacked Deep Bidirectional Recurrent Neural Network

Directory of Open Access Journals (Sweden)

Buzhong Zhang

2018-05-01

Full Text Available Residue solvent accessibility is closely related to the spatial arrangement and packing of residues. Predicting the solvent accessibility of a protein is an important step to understand its structure and function. In this work, we present a deep learning method to predict residue solvent accessibility, which is based on a stacked deep bidirectional recurrent neural network applied to sequence profiles. To capture more long-range sequence information, a merging operator was proposed when bidirectional information from hidden nodes was merged for outputs. Three types of merging operators were used in our improved model, with a long short-term memory network performing as a hidden computing node. The trained database was constructed from 7361 proteins extracted from the PISCES server using a cut-off of 25% sequence identity. Sequence-derived features including position-specific scoring matrix, physical properties, physicochemical characteristics, conservation score and protein coding were used to represent a residue. Using this method, predictive values of continuous relative solvent-accessible area were obtained, and then, these values were transformed into binary states with predefined thresholds. Our experimental results showed that our deep learning method improved prediction quality relative to current methods, with mean absolute error and Pearson’s correlation coefficient values of 8.8% and 74.8%, respectively, on the CB502 dataset and 8.2% and 78%, respectively, on the Manesh215 dataset.

Protein Solvent-Accessibility Prediction by a Stacked Deep Bidirectional Recurrent Neural Network.

Science.gov (United States)

Zhang, Buzhong; Li, Linqing; Lü, Qiang

2018-05-25

Residue solvent accessibility is closely related to the spatial arrangement and packing of residues. Predicting the solvent accessibility of a protein is an important step to understand its structure and function. In this work, we present a deep learning method to predict residue solvent accessibility, which is based on a stacked deep bidirectional recurrent neural network applied to sequence profiles. To capture more long-range sequence information, a merging operator was proposed when bidirectional information from hidden nodes was merged for outputs. Three types of merging operators were used in our improved model, with a long short-term memory network performing as a hidden computing node. The trained database was constructed from 7361 proteins extracted from the PISCES server using a cut-off of 25% sequence identity. Sequence-derived features including position-specific scoring matrix, physical properties, physicochemical characteristics, conservation score and protein coding were used to represent a residue. Using this method, predictive values of continuous relative solvent-accessible area were obtained, and then, these values were transformed into binary states with predefined thresholds. Our experimental results showed that our deep learning method improved prediction quality relative to current methods, with mean absolute error and Pearson's correlation coefficient values of 8.8% and 74.8%, respectively, on the CB502 dataset and 8.2% and 78%, respectively, on the Manesh215 dataset.

Bidirectional communication using delay coupled chaotic directly ...

Indian Academy of Sciences (India)

A symmetric bidirectional coupling is identified as a suitable method for isochronal synchronization of such lasers. The optimum values of coupling and feedback strength that can provide maximum quality of synchronization are identified. This method is successfully employed for encoding/decoding both analog and digital ...

A new approach to the retrieval of surface properties from earthshine measurements

Energy Technology Data Exchange (ETDEWEB)

Spurr, R.J.D. E-mail: rspurr@cfa.harvard.edu

2004-01-01

Instruments such as the MODIS and MISR radiometers on EOS AM-1, and POLDER on ADEOS have been deployed for the remote sensing retrieval of surface properties. Typically, retrieval algorithms use linear combinations of semi-empirical bidirectional reflectance distribution function (BRDF) kernels to model surface reflectance. The retrieval proceeds in two steps; first, an atmospheric correction relates surface BRDF to top-of-atmosphere (TOA) reflectances, then regression is used to establish the linear coefficients used in the kernel combination. BRDF kernels may also depend on a number of physical or empirical non-linear parameters (e.g. ocean wind speed for a specular BRDF); such parameters are usually assumed known. A major source of error in this retrieval comes from lack of knowledge of planetary boundary layer (PBL) aerosol properties. In this paper, we present a different approach to surface property retrieval. For the radiative transfer simulations, we use the discrete ordinate LIDORT model, which has the capability to generate simultaneous fields of radiances and weighting functions in a multiply scattering multi-layer atmosphere. Surface-atmosphere coupling due to multiple scattering and reflection effects is treated in full; the use of an atmospheric correction is not required. Further, it is shown that sensitivities of TOA reflectances to both linear and non-linear surface BRDF parameters may be established directly by explicit analytic differentiation of the discrete ordinate radiative transfer equations. Surface properties may thus be retrieved directly and conveniently from satellite measurements using standard non-linear fitting methods. In the fitting for BRDF parameters, lower-boundary aerosol properties can either be retrieved as auxiliary parameters, or they can be regarded as forward model parameter errors. We present examples of simulated radiances and surface/aerosol weighting functions for combinations of multi-angle measurements at several

A new approach to the retrieval of surface properties from earthshine measurements

International Nuclear Information System (INIS)

Spurr, R.J.D.

2004-01-01

Instruments such as the MODIS and MISR radiometers on EOS AM-1, and POLDER on ADEOS have been deployed for the remote sensing retrieval of surface properties. Typically, retrieval algorithms use linear combinations of semi-empirical bidirectional reflectance distribution function (BRDF) kernels to model surface reflectance. The retrieval proceeds in two steps; first, an atmospheric correction relates surface BRDF to top-of-atmosphere (TOA) reflectances, then regression is used to establish the linear coefficients used in the kernel combination. BRDF kernels may also depend on a number of physical or empirical non-linear parameters (e.g. ocean wind speed for a specular BRDF); such parameters are usually assumed known. A major source of error in this retrieval comes from lack of knowledge of planetary boundary layer (PBL) aerosol properties. In this paper, we present a different approach to surface property retrieval. For the radiative transfer simulations, we use the discrete ordinate LIDORT model, which has the capability to generate simultaneous fields of radiances and weighting functions in a multiply scattering multi-layer atmosphere. Surface-atmosphere coupling due to multiple scattering and reflection effects is treated in full; the use of an atmospheric correction is not required. Further, it is shown that sensitivities of TOA reflectances to both linear and non-linear surface BRDF parameters may be established directly by explicit analytic differentiation of the discrete ordinate radiative transfer equations. Surface properties may thus be retrieved directly and conveniently from satellite measurements using standard non-linear fitting methods. In the fitting for BRDF parameters, lower-boundary aerosol properties can either be retrieved as auxiliary parameters, or they can be regarded as forward model parameter errors. We present examples of simulated radiances and surface/aerosol weighting functions for combinations of multi-angle measurements at several

Block-classified bidirectional motion compensation scheme for wavelet-decomposed digital video

Energy Technology Data Exchange (ETDEWEB)

Zafar, S. [Argonne National Lab., IL (United States). Mathematics and Computer Science Div.; Zhang, Y.Q. [David Sarnoff Research Center, Princeton, NJ (United States); Jabbari, B. [George Mason Univ., Fairfax, VA (United States)

1997-08-01

In this paper the authors introduce a block-classified bidirectional motion compensation scheme for the previously developed wavelet-based video codec, where multiresolution motion estimation is performed in the wavelet domain. The frame classification structure described in this paper is similar to that used in the MPEG standard. Specifically, the I-frames are intraframe coded, the P-frames are interpolated from a previous I- or a P-frame, and the B-frames are bidirectional interpolated frames. They apply this frame classification structure to the wavelet domain with variable block sizes and multiresolution representation. They use a symmetric bidirectional scheme for the B-frames and classify the motion blocks as intraframe, compensated either from the preceding or the following frame, or bidirectional (i.e., compensated based on which type yields the minimum energy). They also introduce the concept of F-frames, which are analogous to P-frames but are predicted from the following frame only. This improves the overall quality of the reconstruction in a group of pictures (GOP) but at the expense of extra buffering. They also study the effect of quantization of the I-frames on the reconstruction of a GOP, and they provide intuitive explanation for the results. In addition, the authors study a variety of wavelet filter-banks to be used in a multiresolution motion-compensated hierarchical video codec.

Bidirectional relations between work-related stress, sleep quality and perseverative cognition.

Science.gov (United States)

Van Laethem, Michelle; Beckers, Debby G J; Kompier, Michiel A J; Kecklund, Göran; van den Bossche, Seth N J; Geurts, Sabine A E

2015-11-01

In this longitudinal two-wave study, bidirectional relations between work-related stress and sleep quality were examined. Moreover, it was investigated whether perseverative cognition is a potential underlying mechanism in this association, related to both work-related stress and sleep quality. A randomly selected sample of Dutch employees received an online survey in 2012 and 2013. Of all invited employees, 877 participated in both waves. Structural equation modeling was performed to analyze the data. We found evidence for reversed relations between work-related stress and sleep quality. Specifically, when controlling for perseverative cognition, work-related stress was not directly related to subsequent sleep quality, but low sleep quality was associated with an increase in work-related stress over time. Moreover, negative bidirectional associations over time were found between perseverative cognition and sleep quality, and positive bidirectional associations were found between work-related stress and perseverative cognition. Lastly, a mediation analysis showed that perseverative cognition fully mediated the relationship between work-related stress and sleep quality. The study findings suggest that perseverative cognition could be an important underlying mechanism in the association between work-related stress and sleep quality. The bidirectionality of the studied relationships could be an indication of a vicious cycle, in which work-related stress, perseverative cognition, and sleep quality mutually influence each other over time. Copyright © 2015 Elsevier Inc. All rights reserved.

Personalized recommendation based on heat bidirectional transfer

Science.gov (United States)

Ma, Wenping; Feng, Xiang; Wang, Shanfeng; Gong, Maoguo

2016-02-01

Personalized recommendation has become an increasing popular research topic, which aims to find future likes and interests based on users' past preferences. Traditional recommendation algorithms pay more attention to forecast accuracy by calculating first-order relevance, while ignore the importance of diversity and novelty that provide comfortable experiences for customers. There are some levels of contradictions between these three metrics, so an algorithm based on bidirectional transfer is proposed in this paper to solve this dilemma. In this paper, we agree that an object that is associated with history records or has been purchased by similar users should be introduced to the specified user and recommendation approach based on heat bidirectional transfer is proposed. Compared with the state-of-the-art approaches based on bipartite network, experiments on two benchmark data sets, Movielens and Netflix, demonstrate that our algorithm has better performance on accuracy, diversity and novelty. Moreover, this method does better in exploiting long-tail commodities and cold-start problem.

Synchronization and bidirectional communication without delay line using strong mutually coupled semiconductor lasers

Science.gov (United States)

Li, Guang-Hui; Wang, An-Bang; Feng, Ye; Wang, Yang

2010-07-01

This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers' outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides (±6%), the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication.

Synchronization and bidirectional communication without delay line using strong mutually coupled semiconductor lasers

International Nuclear Information System (INIS)

Guang-Hui, Li; An-Bang, Wang; Ye, Feng; Yang, Wang

2010-01-01

This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers' outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides (±6%), the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication. (general)

The Bi-Directional Prediction of Carbon Fiber Production Using a Combination of Improved Particle Swarm Optimization and Support Vector Machine.

Science.gov (United States)

Xiao, Chuncai; Hao, Kuangrong; Ding, Yongsheng

2014-12-30

This paper creates a bi-directional prediction model to predict the performance of carbon fiber and the productive parameters based on a support vector machine (SVM) and improved particle swarm optimization (IPSO) algorithm (SVM-IPSO). In the SVM, it is crucial to select the parameters that have an important impact on the performance of prediction. The IPSO is proposed to optimize them, and then the SVM-IPSO model is applied to the bi-directional prediction of carbon fiber production. The predictive accuracy of SVM is mainly dependent on its parameters, and IPSO is thus exploited to seek the optimal parameters for SVM in order to improve its prediction capability. Inspired by a cell communication mechanism, we propose IPSO by incorporating information of the global best solution into the search strategy to improve exploitation, and we employ IPSO to establish the bi-directional prediction model: in the direction of the forward prediction, we consider productive parameters as input and property indexes as output; in the direction of the backward prediction, we consider property indexes as input and productive parameters as output, and in this case, the model becomes a scheme design for novel style carbon fibers. The results from a set of the experimental data show that the proposed model can outperform the radial basis function neural network (RNN), the basic particle swarm optimization (PSO) method and the hybrid approach of genetic algorithm and improved particle swarm optimization (GA-IPSO) method in most of the experiments. In other words, simulation results demonstrate the effectiveness and advantages of the SVM-IPSO model in dealing with the problem of forecasting.

The Bi-Directional Prediction of Carbon Fiber Production Using a Combination of Improved Particle Swarm Optimization and Support Vector Machine

Directory of Open Access Journals (Sweden)

Chuncai Xiao

2014-12-01

Full Text Available This paper creates a bi-directional prediction model to predict the performance of carbon fiber and the productive parameters based on a support vector machine (SVM and improved particle swarm optimization (IPSO algorithm (SVM-IPSO. In the SVM, it is crucial to select the parameters that have an important impact on the performance of prediction. The IPSO is proposed to optimize them, and then the SVM-IPSO model is applied to the bi-directional prediction of carbon fiber production. The predictive accuracy of SVM is mainly dependent on its parameters, and IPSO is thus exploited to seek the optimal parameters for SVM in order to improve its prediction capability. Inspired by a cell communication mechanism, we propose IPSO by incorporating information of the global best solution into the search strategy to improve exploitation, and we employ IPSO to establish the bi-directional prediction model: in the direction of the forward prediction, we consider productive parameters as input and property indexes as output; in the direction of the backward prediction, we consider property indexes as input and productive parameters as output, and in this case, the model becomes a scheme design for novel style carbon fibers. The results from a set of the experimental data show that the proposed model can outperform the radial basis function neural network (RNN, the basic particle swarm optimization (PSO method and the hybrid approach of genetic algorithm and improved particle swarm optimization (GA-IPSO method in most of the experiments. In other words, simulation results demonstrate the effectiveness and advantages of the SVM-IPSO model in dealing with the problem of forecasting.

A Bidirectional Multi-Port DC-DC Converter Integrating Voltage Equalizer

DEFF Research Database (Denmark)

Chen, Jianfei; Hou, Shiying; Deng, Fujin

2015-01-01

A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalize...... battery modules with different voltages. Simulation results has shown the feasibility of the proposed converter.......A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalized...

Near-opposition martian limb-darkening: Quantification and implication for visible-near-infrared bidirectional reflectance studies.

Science.gov (United States)

de Grenier, Muriel; Pinet, Patrick C.

1995-06-01

A nearly global coverage of the martian eastern hemisphere, acquired under small phase angles and varying observational geometries conditions, has been produced from 1988 opposition by spectral (0.5-1 μm) imaging data obtained at the Pic du Midi Observatory in France. From this data set, the methodology presented here permits a systematic analysis of martian photometric behavior at a regional scale of 100-300 km in the visible and near-infrared. The quantification of limb-darkening as a function of wavelength and surface albedo gives access in martian regional properties as a function of wavelength and surface albedo and results in the production of visible and near-infrared geometric albedo maps. A linear relation between the limb darkening parameter k and geometric albedo exists in the near infrared. Based on laboratory studies, it suggests a spectral response of particulate type for the martian soil. Conversely, in the visible, the value of k parameter is 0.6 independent of albedo and is consistent with a single scattering photometric behavior in the surface layer. However, the observed change in the martian photometry from single to multiple scattering may be partially due to a large contribution of atmospheric scattering above 0.7 μm. In the absence of a multitemporal dataset analysis, it must be emphasized that the present results are a priori only pertinent to the atmospheric and surface conditions existing on Mars at the time of observation. However, this analysis may contribute to characterize some physical properties, such as surface roughness. In the near-infrared, for bright terrains, k tends to 0.8 and agrees with the presence of very fine particulate materials. Photometry of dark areas is more irregular (0.48 duricrust. Finally, we evaluate the influence of reflectance geometrical effects on the multispectral and spectroscopic data of the martian surface.

A New Bi-Directional Projection Model Based on Pythagorean Uncertain Linguistic Variable

OpenAIRE

Huidong Wang; Shifan He; Xiaohong Pan

2018-01-01

To solve the multi-attribute decision making (MADM) problems with Pythagorean uncertain linguistic variable, an extended bi-directional projection method is proposed. First, we utilize the linguistic scale function to convert uncertain linguistic variable and provide a new projection model, subsequently. Then, to depict the bi-directional projection method, the formative vectors of alternatives and ideal alternatives are defined. Furthermore, a comparative analysis with projection model is co...

Nanotechnology to rescue bacterial bidirectional extracellular electron transfer in bioelectrochemical systems

KAUST Repository

Kalathil, Shafeer

2016-03-17

An electrically active bacterium transports its metabolically generated electrons to insoluble substrates such as electrodes via a process known as extracellular electron transport (EET). Bacterial EET is a crucial process in the geochemical cycling of metals, bioremediation and bioenergy devices such as microbial fuel cells (MFCs). Recently, it has been found that electroactive bacteria can reverse their respiratory pathways by accepting electrons from a negatively poised electrode to produce high-value chemicals such as ethanol in a process termed as microbial electrosynthesis (MES). A poor electrical connection between bacteria and the electrode hinders the EET and MES processes significantly. Also, the bidirectional EET process is sluggish and needs to be improved drastically to extend its practical applications. Several attempts have been undertaken to improve the bidirectional EET by employing various advanced nanostructured materials such as carbon nanotubes and graphene. This review covers the recent progress in the bacterial bidirectional EET processes using advanced nanostructures in the light of current understandings of bacteria–nanomaterial interactions.

GPS Multipath Fade Measurements to Determine L-Band Ground Reflectivity Properties

Science.gov (United States)

Kavak, Adnan; Xu, Guang-Han; Vogel, Wolfhard J.

1996-01-01

In personal satellite communications, especially when the line-of-sight is clear, ground specular reflected signals along with direct signals are received by low gain, almost omni-directional subscriber antennas. A six-channel, C/A code processing, GPS receiver with an almost omni-directional patch antenna was used to take measurements over three types of ground to characterize 1.575 GHz specular ground reflections and ground dielectric properties. Fade measurements were taken over grass, asphalt, and lake water surfaces by placing the antenna in a vertical position at a fixed height from the ground. Electrical characteristics (conductivity and dielectric constant) of these surfaces (grass, asphalt, lake water) were obtained by matching computer simulations to the experimental results.

Improved algorithm for estimating optical properties of food and biological materials using spatially-resolved diffuse reflectance

Science.gov (United States)

In this research, the inverse algorithm for estimating optical properties of food and biological materials from spatially-resolved diffuse reflectance was optimized in terms of data smoothing, normalization and spatial region of reflectance profile for curve fitting. Monte Carlo simulation was used ...

Inherent optical properties and remote sensing reflectance of Pomeranian lakes (Poland

Directory of Open Access Journals (Sweden)

Dariusz Ficek

2012-11-01

Full Text Available This paper describes the results of comprehensive empirical studies of theinherent optical properties (IOPs, the remote sensing reflectance Rrs(λ andthe contents of the principal optically active components (OAC i.e. coloureddissolved organic matter (CDOM, suspended particulate matter (SPM andchlorophyll a, in the waters of 15 lakes in Polish Pomerania in 2007-2010.It presents numerous spectra of the total absorption a(λ andscattering b(λ ≈ bp(λ of light in the visibleband (400-700 nm for surface waters, and separately, spectra of absorptionby CDOM aCDOM(λ and spectra of the mass-specificcoefficients of absorption ap*(SPM(λ and scatteringbp*(SPM(λ by SPM. The properties of these lake waters are highly diverse, but all of them can beclassified as Case 2 waters (according to the optical classification by Morel& Prieur 1977 and they all have a relatively high OAC content. The lakeswere conventionally divided into three types: Type I lakes have the lowestOAC concentrations (chlorophyll concentration Ca = (8.76 ± 7.4 mg m-3 and CDOM absorption coefficientsaCDOM(440 = (0.57 ± 0.22 m-1 (i.e. mean and standarddeviation, and optical properties (including spectra of Rrs(λresembling those of Baltic waters. Type II waters have exceptionally highcontents of CDOM (aCDOM(440 = (15.37 ± 1.54 m-1,and hence appear brown in daylight and have very low reflectancesRrs(λ (of the order of 0.001 sr-1. Type III waters arehighly eutrophic and contain large amounts of suspended matter, includingphytoplankton ((CSPM = (47.0 ± 39.4 g m-3,Ca = (86.6 ± 61.5 mg m-3; aCDOM(440 = (2.77 ± 0.86 m-1. Hence the reflectances Rrs(λof these type of waters are on average one order of magnitude higher thanthose of the other natural waters, reaching maximum values of 0.03 sr-1in λ bands 560-580 nm and 690-720 nm (see Ficek et al. 2011. Thearticle provides a number of empirical formulas approximating therelationships between the properties of these lake waters.

Bidirectional User Throughput Maximization Based on Feedback Reduction in LiFi Networks

OpenAIRE

Soltani, Mohammad Dehghani; Wu, Xiping; Safari, Majid; Haas, Harald

2017-01-01

Channel adaptive signalling, which is based on feedback, can result in almost any performance metric enhancement. Unlike the radio frequency (RF) channel, the optical wireless communications (OWCs) channel is fairly static. This feature enables a potential improvement of the bidirectional user throughput by reducing the amount of feedback. Light-Fidelity (LiFi) is a subset of OWCs, and it is a bidirectional, high-speed and fully networked wireless communication technology where visible light ...

Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties.

Science.gov (United States)

Vishwanath, Karthik; Chang, Kevin; Klein, Daniel; Deng, Yu Feng; Chang, Vivide; Phelps, Janelle E; Ramanujam, Nimmi

2011-02-01

Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.

Clinico-serologic co-relation in bi-directional ABO incompatible hemopoietic stem cell transplantation

Directory of Open Access Journals (Sweden)

Sabita Basu

2015-01-01

Full Text Available Background: The ABO blood group system is of prime significance in red cell transfusion and organ transplantation. However, ABO compatibility is not critical in allogenic hemopoietic stem cell transplantation (HSCT and approximately 40-50% of hemopoietic stem cell transplants are ABO incompatible. This incompatibility may be major, minor or bi-directional. Though there are descriptions of transfusion practice and protocols in ABO incompatible HSCT, there are considerable variations and transfusion support in these patients can be very challenging. Aims: The immunohematologic observations in two cases of bi-directional ABO incompatible HSCT have been described, and clinico-serologic correlation has been attempted. Materials and Methods: In both cases, peripheral blood stem cell harvests were obtained using the Cobe spectra cell separator. Immunohematologic assessments in the donor and recipient were done as a part of pre HSCT evaluation. Both the standard tube technique and column agglutination method (Ortho Biovue Micro Bead System was used. Antibody screen was done by column agglutination method using three cell panel (Surgiscreen cells. Isoagglutinin titration was done by the master dilution method and standard validated techniques were used. Results: The pattern of laboratory findings in the two cases was different and so were the clinical outcomes. Although there was early engraftment in the first case, the second case developed pure red cell aplasia and this was well-reflected in the immunohematologic assessments. Conclusion: Immunohematologic assessment correlated well with the clinical picture and could be used to predict clinical outcome and onset of complications in ABO incompatible HSCT.

Bidirectional pulser made from pulse lines for linear induction accelerators

International Nuclear Information System (INIS)

Hotta, E.; Mori, T.; Kobayashi, T.; Okino, A.; Haginomori, E.; Ko, K.C.

1996-01-01

In order to obtain high-current charged particle beams, linear induction accelerators (LIA's) of two types have been already constructed. Conventional LIA's adopt a unidirectional pulse injected from an external pulser. The other LIA's, one of which has been proposed and constructed by Pavlovskii et al., have accelerating cavities made from pulse forming lines (PFL's). In this case, no magnetic core loaded in the cavity is necessary. However, the injected pulse must be a bidirectional one. Since a part of the voltage pulse with reversed polarity is used to accelerate a beam, it is possible to make the time integral of the output voltage zero. Thus the final magnetic energy stored in the cavity can be made zero at the end of the pulse, and the pulser-accelerator system attains the energy transfer efficiency of 100%. Accelerators of this type can be divided into two kinds, one of which has cavities with internal energy storage, and the other has cavities with energy injected from external bidirectional pulsers. The accelerator of latter type has been first proposed by Smith, but it has not been realized. Several bidirectional pulsers, which consist of three individual PFL's with arbitrary impedances and a closing switch, are analyzed. Output voltages are analytically calculated by using the method proposed by Dommel for digital computations of electromagnetic transients in networks, and conditions for attaining the maximum efficiency of energy transfer from the pulser to the beam are derived. Thus, 4 bidirectional pulsers of internal energy storage type and 2 of external pulse injection type with energy transfer efficiency of 100% are obtained, including the pulsers already reported by other authors

Determination of acoustic properties of thin polymer films utilizing the frequency dependence of the reflection coefficient of ultrasound.

Science.gov (United States)

Tohmyoh, Hironori; Sakamoto, Yuhei

2015-11-01

This paper reports on a technique to measure the acoustic properties of a thin polymer film utilizing the frequency dependence of the reflection coefficient of ultrasound reflected back from a system comprising a reflection plate, the film, and a material that covers the film. The frequency components of the echo reflected from the back of the plate, where the film is attached, take their minimum values at the resonant frequency, and from these frequency characteristics, the acoustic impedance, sound velocity, and the density of the film can be determined. We applied this technique to characterize an ion exchange membrane, which has high water absorbability, and successfully determined the acoustic properties of the membrane without getting it wet.

Strong electron bidirectional anisotropies in the distant tail: ISEE 3 observations of polar rain

International Nuclear Information System (INIS)

Baker, D.N.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; Zwickl, R.D.; Slavin, J.A.; Smith, E.J.

1986-01-01

A detailed observational treatment of bidirectional electrons (--50 to 50 eV)in the distant magnetotail (rapprox. >100 R/sub E/) is presented. It is found that electrons in this energy range commonly exhibit strong, field-aligned anisotropies in the tail lobes. Because of large tail motions, the ISEE 3 data provide extensive sampling of both the north and south lobes in rapid succession. These data demonstrate directly the strong asymmetries that exist between the north and south lobes at any one time. The bidirectional fluxes are found to occur predominantly in the lobe directly connected to the sunward interplanetary magnetic field in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Electron anisotropy and magnetic field data are presented which show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations. Thus we demonstrate the open nature of the distant magnetopause and show that the source of the higher-energy, bidirectional lobe electrons is the tailward directed electron heat flux population in the distant magnetosheath. Taken together, the present evidence suggests that the bidirectional electrons that we observe in the distant tail are closely related to the polar rain electrons observed previously at lower altitudes. Furthermore, these data provide strong evidence that the distant tail is composed largely of open magnetic field lines in contradistinction to some recently advanced models

5W1H Information Extraction with CNN-Bidirectional LSTM

Science.gov (United States)

Nurdin, A.; Maulidevi, N. U.

2018-03-01

In this work, information about who, did what, when, where, why, and how on Indonesian news articles were extracted by combining Convolutional Neural Network and Bidirectional Long Short-Term Memory. Convolutional Neural Network can learn semantically meaningful representations of sentences. Bidirectional LSTM can analyze the relations among words in the sequence. We also use word embedding word2vec for word representation. By combining these algorithms, we obtained F-measure 0.808. Our experiments show that CNN-BLSTM outperforms other shallow methods, namely IBk, C4.5, and Naïve Bayes with the F-measure 0.655, 0.645, and 0.595, respectively.

Bidirectional electron anisotropies in the distant tail: ISEE-3 observations of polar rain

International Nuclear Information System (INIS)

Baker, D.N.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; Zwickl, R.D.; Slavin, J.A.; Smith, E.J.

1985-01-01

A detailed observational treatment of bidirectional electrons (50 approx.500 eV) in the distant magnetotail (r greater than or equal to 100 R/sub E/) is presented. It is found that electrons in this energy range commonly exhibit strong, field-aligned anisotropies in the tail lobes. Because of large tail motions, the ISEE-3 data provide extensive sampling of both the north and south lobes in rapid succession, demonstrating directly the strong asymmetries that exist between the north and south lobes at any one time. The bidirectional fluxes are found to occur predominantly in the lobe directly connected to the sunward IMF in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Electron anisotropy and magnetic field data are presented which show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations. Taken together, the present evidence suggests that the bidirectional electrons that we observe in the distant tail are closely related to the polar rain electrons observed previously at lower altitudes. Furthermore, these data provide strong evidence that the distant tail is comprised largely of open magnetic field lines in contradistinction to some recently advanced models

Bidirectional soliton spectral tunneling effects in the regime of optical event horizon

DEFF Research Database (Denmark)

Gu, Jie; Guo, Hairun; Wang, Shaofei

2015-01-01

We study the cross-phase-modulation-induced soliton spectral shifting in the regime of the optical event horizon. The perturbed soliton to either red-shifting or blue-shifting is controllable, which could evoke bidirectional soliton spectral tunneling effects.......We study the cross-phase-modulation-induced soliton spectral shifting in the regime of the optical event horizon. The perturbed soliton to either red-shifting or blue-shifting is controllable, which could evoke bidirectional soliton spectral tunneling effects....

Bidirectional Relationship between Cognitive Function and Pneumonia

Science.gov (United States)

Shah, Faraaz Ali; Pike, Francis; Alvarez, Karina; Angus, Derek; Newman, Anne B.; Lopez, Oscar; Tate, Judith; Kapur, Vishesh; Wilsdon, Anthony; Krishnan, Jerry A.; Hansel, Nadia; Au, David; Avdalovic, Mark; Fan, Vincent S.; Barr, R. Graham

2013-01-01

Rationale: Relationships between chronic health conditions and acute infections remain poorly understood. Preclinical studies suggest crosstalk between nervous and immune systems. Objectives: To determine bidirectional relationships between cognition and pneumonia. Methods: We conducted longitudinal analyses of a population-based cohort over 10 years. We determined whether changes in cognition increase risk of pneumonia hospitalization by trajectory analyses and joint modeling. We then determined whether pneumonia hospitalization increased risk of subsequent dementia using a Cox model with pneumonia as a time-varying covariate. Measurements and Main Results: Of the 5,888 participants, 639 (10.9%) were hospitalized with pneumonia at least once. Most participants had normal cognition before pneumonia. Three cognition trajectories were identified: no, minimal, and severe rapid decline. A greater proportion of participants hospitalized with pneumonia were on trajectories of minimal or severe decline before occurrence of pneumonia compared with those never hospitalized with pneumonia (proportion with no, minimal, and severe decline were 67.1%, 22.8%, and 10.0% vs. 76.0%, 19.3%, and 4.6% for participants with and without pneumonia, respectively; P pneumonia, even in those with normal cognition and physical function before pneumonia (β = −0.02; P pneumonia were subsequently at an increased risk of dementia (hazard ratio, 2.24 [95% confidence interval, 1.62–3.11]; P = 0.01). Associations were independent of demographics, health behaviors, other chronic conditions, and physical function. Bidirectional relationship did not vary based on severity of disease, and similar associations were noted for those with severe sepsis and other infections. Conclusions: A bidirectional relationship exists between pneumonia and cognition and may explain how a single episode of infection in well-appearing older individuals accelerates decline in chronic health conditions and loss of

Personalized recommendation based on preferential bidirectional mass diffusion

Science.gov (United States)

Chen, Guilin; Gao, Tianrun; Zhu, Xuzhen; Tian, Hui; Yang, Zhao

2017-03-01

Recommendation system provides a promising way to alleviate the dilemma of information overload. In physical dynamics, mass diffusion has been used to design effective recommendation algorithms on bipartite network. However, most of the previous studies focus overwhelmingly on unidirectional mass diffusion from collected objects to uncollected objects, while overlooking the opposite direction, leading to the risk of similarity estimation deviation and performance degradation. In addition, they are biased towards recommending popular objects which will not necessarily promote the accuracy but make the recommendation lack diversity and novelty that indeed contribute to the vitality of the system. To overcome the aforementioned disadvantages, we propose a preferential bidirectional mass diffusion (PBMD) algorithm by penalizing the weight of popular objects in bidirectional diffusion. Experiments are evaluated on three benchmark datasets (Movielens, Netflix and Amazon) by 10-fold cross validation, and results indicate that PBMD remarkably outperforms the mainstream methods in accuracy, diversity and novelty.

Experimental method for testing diffraction properties of reflection waveguide holograms.

Science.gov (United States)

Xie, Yi; Kang, Ming-Wu; Wang, Bao-Ping

2014-07-01

Waveguide holograms' diffraction properties include peak wavelength and diffraction efficiency, which play an important role in determining their display performance. Based on the record and reconstruction theory of reflection waveguide holograms, a novel experimental method for testing diffraction properties is introduced and analyzed in this paper, which uses a plano-convex lens optically contacted to the surface of the substrate plate of the waveguide hologram, so that the diffracted light beam can be easily detected. Then an experiment is implemented. The designed reconstruction wavelength of the test sample is 530 nm, and its diffraction efficiency is 100%. The experimental results are a peak wavelength of 527.7 nm and a diffraction efficiency of 94.1%. It is shown that the tested value corresponds well with the designed value.

The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly

Science.gov (United States)

Siddique, Radwanul Hasan; Gomard, Guillaume; Hölscher, Hendrik

2015-04-01

The glasswing butterfly (Greta oto) has, as its name suggests, transparent wings with remarkable low haze and reflectance over the whole visible spectral range even for large view angles of 80°. This omnidirectional anti-reflection behaviour is caused by small nanopillars covering the transparent regions of its wings. In difference to other anti-reflection coatings found in nature, these pillars are irregularly arranged and feature a random height and width distribution. Here we simulate the optical properties with the effective medium theory and transfer matrix method and show that the random height distribution of pillars significantly reduces the reflection not only for normal incidence but also for high view angles.

Design of PI Controlled Non Isolated Bidirectional DC to DC Converter for Electric Vehicle Application

Science.gov (United States)

Geetha, A.; Subramani, C.; Thamizh Thentral, T. M.; Krithika, V.; Usha, S.

2018-04-01

Non isolated Bidirectional DC-DC Converter (NIBDDC) is a good interface between DC source and inverter Fed induction motor drive. This paper deals with comparison between open loop and PI controlled Bidirectional DC to DC Converter Inverter System (BDDCIS). The modelling and control of BDDC is becomes an important issue. Open loop BDDCIS and closed loop PI controlled BDDCIS are designed, modelled and simulated using Matlab- simulink and their results are presented. The investigations indicate superior performance of PI controlled BDDCIS. The proposed BDDCIS has advantages like bidirectional power transfer ability, reduced hardware count and improved dynamic response.

Microwave reflection properties of planar anisotropy Fe50Ni50 powder/paraffin composites

International Nuclear Information System (INIS)

Wei Jian-Qiang; Zhang Zhao-Qi; Han Rui; Wang Tao; Li Fa-Shen

2012-01-01

The reflection properties of planar anisotropy Fe 50 Ni 50 powder/paraffin composites have been studied in the microwave frequency range. The permeability of Fe 50 Ni 50 powder/paraffin composites is greatly enhanced by introducing the planar anisotropy, and can be further enhanced by using a rotational orientation method. The complex permeability can be considered as the superposition of two types of magnetic resonance. The resonance peak at high frequency is attributed to the natural resonance, while the peak at low frequency is attributed to the domain-wall resonance. The simulated results of the microwave reflectivity show that the matching thickness, peak frequency, permeability, and permittivity are closely related to the quarter wavelength matching condition. The Fe 50 Ni 50 powder/paraffin composites can be attractive candidates for thinner microwave absorbers in the L-band (1–2 GHz). (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Parenting and children's externalizing behavior: Bidirectionality during toddlerhood

NARCIS (Netherlands)

Verhoeven, Marjolein; Junger, Marianne; van Aken, Chantal; Dekovic, Maja; van Aken, Marcel A.G.

2010-01-01

This study examined the bidirectional relationship between parenting and boys' externalizing behaviors in a four-wave longitudinal study of toddlers. Participants were 104 intact two-parent families with toddler sons. When their sons were 17, 23, 29, and 35 months of age, mothers and fathers

A Current-Fed Isolated Bidirectional DC-DC Converter

DEFF Research Database (Denmark)

Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng

2017-01-01

This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes...

Stability in Cohen Grossberg-type bidirectional associative memory neural networks with time-varying delays

Science.gov (United States)

Cao, Jinde; Song, Qiankun

2006-07-01

In this paper, the exponential stability problem is investigated for a class of Cohen-Grossberg-type bidirectional associative memory neural networks with time-varying delays. By using the analysis method, inequality technique and the properties of an M-matrix, several novel sufficient conditions ensuring the existence, uniqueness and global exponential stability of the equilibrium point are derived. Moreover, the exponential convergence rate is estimated. The obtained results are less restrictive than those given in the earlier literature, and the boundedness and differentiability of the activation functions and differentiability of the time-varying delays are removed. Two examples with their simulations are given to show the effectiveness of the obtained results.

Evolution of bidirectional sex change and gonochorism in fishes of the gobiid genera Trimma, Priolepis, and Trimmatom

Science.gov (United States)

Sunobe, Tomoki; Sado, Tetsuya; Hagiwara, Kiyoshi; Manabe, Hisaya; Suzuki, Toshiyuki; Kobayashi, Yasuhisa; Sakurai, Makoto; Dewa, Shin-ichi; Matsuoka, Midori; Shinomiya, Akihiko; Fukuda, Kazuya; Miya, Masaki

2017-04-01

Size-advantage and low-density models have been used to explain how mating systems favor hermaphroditism or gonochorism. However, these models do not indicate historical transitions in sexuality. Here, we investigate the evolution of bidirectional sex change and gonochorism by phylogenetic analysis using the mitochondrial gene of the gobiids Trimma (31 species), Priolepis (eight species), and Trimmatom (two species). Trimma and Priolepis formed a clade within the sister group Trimmatom. Gonadal histology and rearing experiments revealed that Trimma marinae, Trimma nasa, and Trimmatom spp. were gonochoric, whereas all other Trimma and Priolepis spp. were bidirectional sex changers or inferred ones. A maximum-likelihood reconstruction analysis demonstrated that the common ancestor of the three genera was gonochoristic. Bidirectional sex change probably evolved from gonochorism in a common ancestor of Trimma and Priolepis. As the gonads of bidirectional sex changers simultaneously contain mature ovarian and immature testicular components or vice versa, individuals are always potentially capable of functioning as females or males, respectively. Monogamy under low-density conditions may have been the ecological condition for the evolution of bidirectional sex change in a common ancestor. As T. marinae and T. nasa are a monophyletic group, gonochorism should have evolved from bidirectional sex change in a common ancestor.

Effect of retardation on the reflectance properties of the metallic Fibonacci quasi-superlattice

International Nuclear Information System (INIS)

Feng Weiguo; Yao Hesheng; Xu Xiang

1989-12-01

Based on the hydrodynamic model theory and the transfer matrix method, we have re-examined the reflection properties by taking account of the retardation effect to the system of the metallic Fibonacci quasi-superlattice. For the normal incident S-polarized Soft X-rays and extreme ultraviolet, we find that the self-similar reflecting spectrum will be restrained with the increasing of the retardation, but for the higher frequency region or at the smaller grazing angle, the self similarity will still exist for the lower generation quasi-superlattice. (author). 19 refs, 2 figs, 1 tab

Effects of Rocket Exhaust on Lunar Soil Reflectance Properties

Science.gov (United States)

Clegg, R. N.; Jolliff, B. L.; Robinson, M. S.; Hapke, B. W.; Plescia, J. B.

2012-12-01

areas; this magnitude is the same, within uncertainty, for all sites, indicating a common process or combination of processes causing differences in reflectance properties of the regolith. Phase-ratio images and photometric data collected over a range of illumination geometries show that a greater separation in reflectance occurs between the HR-BZs and undisturbed areas with increasing phase angle and indicate that the HR-BZs are less backscattering than undisturbed areas. As working hypotheses, we consider the following possibilities to explain BZ reflectance phenomena: change in macroscopic roughness, microscopic modification of surface structure, redistribution of fines (excavation from LR-BZ and deposition in HR-BZ), change in compaction, contamination from fuel, and modification of maturity. The LR-BZ is affected by macroscopic disruption of the surface and increased shadowing. We infer that HR-BZ reflectance has been affected by scouring from particles entrained by exhaust gases with low-angle trajectories. Entrained particles with trajectories greater than a few degrees relative to horizontal travel well beyond the BZ boundary and do not contribute to BZ reflectance variations. Regolith particle interactions with surface soil within HR-BZs may destroy fine-scale surface structure (e.g., "fairy-castle") and decrease macroscopic roughness, contributing to a decrease in backscattering character within the HR-BZ.

Optimization Control of Bidirectional Cascaded DC-AC Converter Systems

DEFF Research Database (Denmark)

Tian, Yanjun

in bidirectional cascaded converter. This research work analyses the control strategies based on the topology of dual active bridges converter cascaded with a three phase inverter. It firstly proposed a dc link voltage and active power coordinative control method for this cascaded topology, and it can reduce dc....... The connections of the renewable energy sources to the power system are mostly through the power electronic converters. Moreover, for high controllability and flexibility, power electronic devices are gradually acting as the interface between different networks in power systems, promoting conventional power...... the bidirectional power flow in the distribution level of power systems. Therefore direct contact of converters introduces significant uncertainties to power system, especially for the stability and reliability. This dissertation studies the optimization control of the two stages directly connected converters...

Bidirectional selection between two classes in complex social networks.

Science.gov (United States)

Zhou, Bin; He, Zhe; Jiang, Luo-Luo; Wang, Nian-Xin; Wang, Bing-Hong

2014-12-19

The bidirectional selection between two classes widely emerges in various social lives, such as commercial trading and mate choosing. Until now, the discussions on bidirectional selection in structured human society are quite limited. We demonstrated theoretically that the rate of successfully matching is affected greatly by individuals' neighborhoods in social networks, regardless of the type of networks. Furthermore, it is found that the high average degree of networks contributes to increasing rates of successful matches. The matching performance in different types of networks has been quantitatively investigated, revealing that the small-world networks reinforces the matching rate more than scale-free networks at given average degree. In addition, our analysis is consistent with the modeling result, which provides the theoretical understanding of underlying mechanisms of matching in complex networks.

Learning to Monitor Machine Health with Convolutional Bi-Directional LSTM Networks.

Science.gov (United States)

Zhao, Rui; Yan, Ruqiang; Wang, Jinjiang; Mao, Kezhi

2017-01-30

In modern manufacturing systems and industries, more and more research efforts have been made in developing effective machine health monitoring systems. Among various machine health monitoring approaches, data-driven methods are gaining in popularity due to the development of advanced sensing and data analytic techniques. However, considering the noise, varying length and irregular sampling behind sensory data, this kind of sequential data cannot be fed into classification and regression models directly. Therefore, previous work focuses on feature extraction/fusion methods requiring expensive human labor and high quality expert knowledge. With the development of deep learning methods in the last few years, which redefine representation learning from raw data, a deep neural network structure named Convolutional Bi-directional Long Short-Term Memory networks (CBLSTM) has been designed here to address raw sensory data. CBLSTM firstly uses CNN to extract local features that are robust and informative from the sequential input. Then, bi-directional LSTM is introduced to encode temporal information. Long Short-Term Memory networks(LSTMs) are able to capture long-term dependencies and model sequential data, and the bi-directional structure enables the capture of past and future contexts. Stacked, fully-connected layers and the linear regression layer are built on top of bi-directional LSTMs to predict the target value. Here, a real-life tool wear test is introduced, and our proposed CBLSTM is able to predict the actual tool wear based on raw sensory data. The experimental results have shown that our model is able to outperform several state-of-the-art baseline methods.

Learning to Monitor Machine Health with Convolutional Bi-Directional LSTM Networks

Directory of Open Access Journals (Sweden)

Rui Zhao

2017-01-01

Full Text Available In modern manufacturing systems and industries, more and more research efforts have been made in developing effective machine health monitoring systems. Among various machine health monitoring approaches, data-driven methods are gaining in popularity due to the development of advanced sensing and data analytic techniques. However, considering the noise, varying length and irregular sampling behind sensory data, this kind of sequential data cannot be fed into classification and regression models directly. Therefore, previous work focuses on feature extraction/fusion methods requiring expensive human labor and high quality expert knowledge. With the development of deep learning methods in the last few years, which redefine representation learning from raw data, a deep neural network structure named Convolutional Bi-directional Long Short-Term Memory networks (CBLSTM has been designed here to address raw sensory data. CBLSTM firstly uses CNN to extract local features that are robust and informative from the sequential input. Then, bi-directional LSTM is introduced to encode temporal information. Long Short-Term Memory networks(LSTMs are able to capture long-term dependencies and model sequential data, and the bi-directional structure enables the capture of past and future contexts. Stacked, fully-connected layers and the linear regression layer are built on top of bi-directional LSTMs to predict the target value. Here, a real-life tool wear test is introduced, and our proposed CBLSTM is able to predict the actual tool wear based on raw sensory data. The experimental results have shown that our model is able to outperform several state-of-the-art baseline methods.

Spectral reflectance properties of iridescent pierid butterfly wings.

Science.gov (United States)

Wilts, Bodo D; Pirih, Primož; Stavenga, Doekele G

2011-06-01

The wings of most pierid butterflies exhibit a main, pigmentary colouration: white, yellow or orange. The males of many species have in restricted areas of the wing upper sides a distinct structural colouration, which is created by stacks of lamellae in the ridges of the wing scales, resulting in iridescence. The amplitude of the reflectance is proportional to the number of lamellae in the ridge stacks. The angle-dependent peak wavelength of the observed iridescence is in agreement with classical multilayer theory. The iridescence is virtually always in the ultraviolet wavelength range, but some species have a blue-peaking iridescence. The spectral properties of the pigmentary and structural colourations are presumably tuned to the spectral sensitivities of the butterflies' photoreceptors.

[Modeling polarimetric BRDF of leaves surfaces].

Science.gov (United States)

Xie, Dong-Hui; Wang, Pei-Juan; Zhu, Qi-Jiang; Zhou, Hong-Min

2010-12-01

The purpose of the present paper is to model a physical polarimetric bidirectional reflectance distribution function (pBRDF), which can character not only the non-Lambertian but also the polarized features in order that the pBRDF can be applied to analyze the relationship between the degree of polarization and the physiological and biochemical parameters of leaves quantitatively later. Firstly, the bidirectional polarized reflectance distributions from several leaves surfaces were measured by the polarized goniometer developed by Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences. The samples of leaves include two pieces of zea mays L. leaves (young leaf and mature leaf) and a piece of E. palcherrima wild leaf. Non-Lambertian characteristics of directional reflectance from the surfaces of these three leaves are obvious. A Cook-Torrance model was modified by coupling the polarized Fresnel equations to simulate the bidirectional polarized reflectance properties of leaves surfaces. The three parameters in the modified pBRDF model, such as diffuse reflectivity, refractive index and roughness of leaf surface were inversed with genetic algorithm (GA). It was found that the pBRDF model can fit with the measured data well. In addition, these parameters in the model are related with both the physiological and biochemical properties and the polarized characteristics of leaves, therefore it is possible to build the relationships between them later.

Encoding Strategy for Maximum Noise Tolerance Bidirectional Associative Memory

National Research Council Canada - National Science Library

Shen, Dan

2003-01-01

In this paper, the Basic Bidirectional Associative Memory (BAM) is extended by choosing weights in the correlation matrix, for a given set of training pairs, which result in a maximum noise tolerance set for BAM...

Effects of target shape and reflection on laser radar cross sections.

Science.gov (United States)

Steinvall, O

2000-08-20

Laser radar cross sections have been evaluated for a number of ideal targets such as cones, spheres, paraboloids, and cylinders by use of different reflection characteristics. The time-independent cross section is the ratio of the cross section of one of these forms to that of a plate with the same maximum radius. The time-dependent laser radar cross section involves the impulse response from the object shape multiplied by the beam's transverse profile and the surface bidirectional reflection distribution function. It can be clearly seen that knowledge of the combined effect of object shape and reflection characteristics is important for determining the shape and the magnitude of the laser radar return. The results of this study are of interest for many laser radar applications such as ranging, three-dimensional imaging-modeling, tracking, antisensor lasers, and target recognition.

Stationary oscillation for nonautonomous bidirectional associative memory neural networks with impulse

International Nuclear Information System (INIS)

Zhang Yinping

2009-01-01

In this paper, we study the existence, uniqueness and global stability of periodic solution (i.e. stationary oscillation) for general bidirectional associative memory neural networks with impulses. Some sufficient conditions are obtained for stationary oscillation of the nonautonomous bidirectional associative memory neural networks with impulses. It is derived by using a new method which is different from those of previous literatures, and a assumption in previous results does not required. The model considered is more general and some previous results are extended and improved. An illustrative example is given to demonstrate the effectiveness and less conservativeness of the obtained results.

Colours sometimes count: awareness and bidirectionality in grapheme-colour synaesthesia.

Science.gov (United States)

Johnson, Addie; Jepma, Marieke; de Jong, Ritske

2007-10-01

Three experiments were conducted with 10 grapheme-colour synaesthetes and 10 matched controls to investigate (a) whether awareness of the inducer grapheme is necessary for synaesthetic colour induction and (b) whether grapheme-colour synaesthesia may be bidirectional in the sense that not only do graphemes induce colours, but that colours influence the processing of graphemes. Using attentional blink and Stroop paradigms with digit targets, we found that some synaesthetes did report "seeing" synaesthetic colours even when they were not able to report the inducing digit. Moreover, congruency effects (effects of matching the colour of digit presentation with the synaesthetic colour associated with that digit) suggested that grapheme-colour synaesthesia can be bidirectional, at least for some synaesthetes.

Bidirectional dc-to-dc Power Converter

Science.gov (United States)

Griesbach, C. R.

1986-01-01

Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

Adapting a regularized canopy reflectance model (REGFLEC) for the retrieval challenges of dryland agricultural systems

KAUST Repository

Houborg, Rasmus

2016-08-20

A regularized canopy reflectance model (REGFLEC) is applied over a dryland irrigated agricultural system in Saudi Arabia for the purpose of retrieving leaf area index (LAI) and leaf chlorophyll content (Chll). To improve the robustness of the retrieved properties, REGFLEC was modified to 1) correct for aerosol and adjacency effects, 2) consider foliar dust effects on modeled canopy reflectances, 3) include spectral information in the red-edge wavelength region, and 4) exploit empirical LAI estimates in the model inversion. Using multi-spectral RapidEye imagery allowed Chll to be retrieved with a Mean Absolute Deviation (MAD) of 7.9 μg cm− 2 (16%), based upon in-situ measurements conducted in fields of alfalfa, Rhodes grass and maize over the course of a growing season. LAI and Chll compensation effects on canopy reflectance were largely avoided by informing the inversion process with ancillary LAI inputs established empirically on the basis of a statistical machine learning technique. As a result, LAI was reproduced with good accuracy, with an overall MAD of 0.42 m2 m− 2 (12.5%). Results highlighted the considerable challenges associated with the translation of at-sensor radiance observations to surface bidirectional reflectances in dryland environments, where issues such as high aerosol loadings and large spatial gradients in surface reflectance from bright desert soils to dark vegetated fields are often present. Indeed, surface reflectances in the visible bands were reduced by up to 60% after correction for such adjacency effects. In addition, dust deposition on leaves required explicit modification of the reflectance sub-model to account for its influence. By implementing these model refinements, REGFLEC demonstrated its utility for within-field characterization of vegetation conditions over the challenging landscapes typical of dryland agricultural regions, offering a means through which improvements can be made in the management of these globally

Unmanned aerial system nadir reflectance and MODIS nadir BRDF-adjusted surface reflectances intercompared over Greenland

Science.gov (United States)

Faulkner Burkhart, John; Kylling, Arve; Schaaf, Crystal B.; Wang, Zhuosen; Bogren, Wiley; Storvold, Rune; Solbø, Stian; Pedersen, Christina A.; Gerland, Sebastian

2017-07-01

Albedo is a fundamental parameter in earth sciences, and many analyses utilize the Moderate Resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF)/albedo (MCD43) algorithms. While derivative albedo products have been evaluated over Greenland, we present a novel, direct comparison with nadir surface reflectance collected from an unmanned aerial system (UAS). The UAS was flown from Summit, Greenland, on 210 km transects coincident with the MODIS sensor overpass on board the Aqua and Terra satellites on 5 and 6 August 2010. Clear-sky acquisitions were available from the overpasses within 2 h of the UAS flights. The UAS was equipped with upward- and downward-looking spectrometers (300-920 nm) with a spectral resolution of 10 nm, allowing for direct integration into the MODIS bands 1, 3, and 4. The data provide a unique opportunity to directly compare UAS nadir reflectance with the MODIS nadir BRDF-adjusted surface reflectance (NBAR) products. The data show UAS measurements are slightly higher than the MODIS NBARs for all bands but agree within their stated uncertainties. Differences in variability are observed as expected due to different footprints of the platforms. The UAS data demonstrate potentially large sub-pixel variability of MODIS reflectance products and the potential to explore this variability using the UAS as a platform. It is also found that, even at the low elevations flown typically by a UAS, reflectance measurements may be influenced by haze if present at and/or below the flight altitude of the UAS. This impact could explain some differences between data from the two platforms and should be considered in any use of airborne platforms.

Linearly and nonlinearly bidirectionally coupled synchronization of hyperchaotic systems

International Nuclear Information System (INIS)

Zhou Jin; Lu Junan; Wu Xiaoqun

2007-01-01

To date, there have been many results about unidirectionally coupled synchronization of chaotic systems. However, much less work is reported on bidirectionally-coupled synchronization. In this paper, we investigate the synchronization of two bidirectionally coupled Chen hyperchaotic systems, which are coupled linearly and nonlinearly respectively. Firstly, linearly coupled synchronization of two hyperchaotic Chen systems is investigated, and a theorem on how to choose the coupling coefficients are developed to guarantee the global asymptotical synchronization of two coupled hyperchaotic systems. Analysis shows that the choice of the coupling coefficients relies on the bound of the chaotic system. Secondly, the nonlinearly coupled synchronization is studied; a sufficient condition for the locally asymptotical synchronization is derived, which is independent of the bound of the hyperchaotic system. Finally, numerical simulations are included to verify the effectiveness and feasibility of the developed theorems

Connecting Neurons to a Mobile Robot: An In Vitro Bidirectional Neural Interface

Science.gov (United States)

Novellino, A.; D'Angelo, P.; Cozzi, L.; Chiappalone, M.; Sanguineti, V.; Martinoia, S.

2007-01-01

One of the key properties of intelligent behaviors is the capability to learn and adapt to changing environmental conditions. These features are the result of the continuous and intense interaction of the brain with the external world, mediated by the body. For this reason “embodiment” represents an innovative and very suitable experimental paradigm when studying the neural processes underlying learning new behaviors and adapting to unpredicted situations. To this purpose, we developed a novel bidirectional neural interface. We interconnected in vitro neurons, extracted from rat embryos and plated on a microelectrode array (MEA), to external devices, thus allowing real-time closed-loop interaction. The novelty of this experimental approach entails the necessity to explore different computational schemes and experimental hypotheses. In this paper, we present an open, scalable architecture, which allows fast prototyping of different modules and where coding and decoding schemes and different experimental configurations can be tested. This hybrid system can be used for studying the computational properties and information coding in biological neuronal networks with far-reaching implications for the future development of advanced neuroprostheses. PMID:18350128

Polarization-based index of refraction and reflection angle estimation for remote sensing applications

Science.gov (United States)

Thilak, Vimal; Voelz, David G.; Creusere, Charles D.

2007-10-01

A passive-polarization-based imaging system records the polarization state of light reflected by objects that are illuminated with an unpolarized and generally uncontrolled source. Such systems can be useful in many remote sensing applications including target detection, object segmentation, and material classification. We present a method to jointly estimate the complex index of refraction and the reflection angle (reflected zenith angle) of a target from multiple measurements collected by a passive polarimeter. An expression for the degree of polarization is derived from the microfacet polarimetric bidirectional reflectance model for the case of scattering in the plane of incidence. Using this expression, we develop a nonlinear least-squares estimation algorithm for extracting an apparent index of refraction and the reflection angle from a set of polarization measurements collected from multiple source positions. Computer simulation results show that the estimation accuracy generally improves with an increasing number of source position measurements. Laboratory results indicate that the proposed method is effective for recovering the reflection angle and that the estimated index of refraction provides a feature vector that is robust to the reflection angle.

Compiling a Bidirectional Dictionary Bridging English and the Sotho ...

African Journals Online (AJOL)

rbr

bi-directional Sesotho sa Leboa ↔ Sesotho, Sesotho sa Leboa ↔ Setswana and ... example, the 100 most frequently used words in Sesotho sa Leboa in ranking .... Consider in this regard a selection of such mutual lexical items with high.

Analyzing asteroid reflectance spectra with numerical tools based on scattering simulations

Science.gov (United States)

Penttilä, Antti; Väisänen, Timo; Markkanen, Johannes; Martikainen, Julia; Gritsevich, Maria; Muinonen, Karri

2017-04-01

We are developing a set of numerical tools that can be used in analyzing the reflectance spectra of granular materials such as the regolith surface of atmosphereless Solar system objects. Our goal is to be able to explain, with realistic numerical scattering models, the spectral features arising when materials are intimately mixed together. We include the space-weathering -type effects in our simulations, i.e., mixing host mineral locally with small inclusions of another material in small proportions. Our motivation for this study comes from the present lack of such tools. The current common practice is to apply a semi-physical approximate model such as some variation of Hapke models [e.g., 1] or the Shkuratov model [2]. These models are expressed in a closed form so that they are relatively fast to apply. They are based on simplifications on the radiative transfer theory. The problem is that the validity of the model is not always guaranteed, and the derived physical properties related to particle scattering properties can be unrealistic [3]. We base our numerical tool into a chain of scattering simulations. Scattering properties of small inclusions inside an absorbing host matrix can be derived using exact methods solving the Maxwell equations of the system. The next step, scattering by a single regolith grain, is solved using a geometrical optics method accounting for surface reflections, internal absorption, and possibly the internal diffuse scattering. The third step involves the radiative transfer simulations of these regolith grains in a macroscopic planar element. The chain can be continued next with shadowing simulation over the target surface elements, and finally by integrating the bidirectional reflectance distribution function over the object's shape. Most of the tools in the proposed chain already exist, and one practical task for us is to tie these together into an easy-to-use toolchain that can be publicly distributed. We plan to open the

Neural coding in graphs of bidirectional associative memories.

Science.gov (United States)

Bouchain, A David; Palm, Günther

2012-01-24

In the last years we have developed large neural network models for the realization of complex cognitive tasks in a neural network architecture that resembles the network of the cerebral cortex. We have used networks of several cortical modules that contain two populations of neurons (one excitatory, one inhibitory). The excitatory populations in these so-called "cortical networks" are organized as a graph of Bidirectional Associative Memories (BAMs), where edges of the graph correspond to BAMs connecting two neural modules and nodes of the graph correspond to excitatory populations with associative feedback connections (and inhibitory interneurons). The neural code in each of these modules consists essentially of the firing pattern of the excitatory population, where mainly it is the subset of active neurons that codes the contents to be represented. The overall activity can be used to distinguish different properties of the patterns that are represented which we need to distinguish and control when performing complex tasks like language understanding with these cortical networks. The most important pattern properties or situations are: exactly fitting or matching input, incomplete information or partially matching pattern, superposition of several patterns, conflicting information, and new information that is to be learned. We show simple simulations of these situations in one area or module and discuss how to distinguish these situations based on the overall internal activation of the module. This article is part of a Special Issue entitled "Neural Coding". Copyright © 2011 Elsevier B.V. All rights reserved.

10 Gb/s bidirectional single fibre long reach PON link with distributed Raman amplification

DEFF Research Database (Denmark)

Tafur Monroy, Idelfonso; Kjær, Rasmus; Jeppesen, Palle

2006-01-01

We report operation of a single fibre bidirectional 80 km long reach PON link with symmetric up- and-downstream data rate of 10 Gb/s supported by distributed Raman fibre amplification only.......We report operation of a single fibre bidirectional 80 km long reach PON link with symmetric up- and-downstream data rate of 10 Gb/s supported by distributed Raman fibre amplification only....

Günther Tulip inferior vena cava filter retrieval using a bidirectional loop-snare technique.

Science.gov (United States)

Ross, Jordan; Allison, Stephen; Vaidya, Sandeep; Monroe, Eric

2016-01-01

Many advanced techniques have been reported in the literature for difficult Günther Tulip filter removal. This report describes a bidirectional loop-snare technique in the setting of a fibrin scar formation around the filter leg anchors. The bidirectional loop-snare technique allows for maximal axial tension and alignment for stripping fibrin scar from the filter legs, a commonly encountered complication of prolonged dwell times.

Computation of the optical properties of turbid media from slope and curvature of spatially resolved reflectance curves

International Nuclear Information System (INIS)

Jäger, Marion; Foschum, Florian; Kienle, Alwin

2013-01-01

The optical properties of turbid media were calculated from the curvature at the radial distance ρ O and the slope at the radial distance ρ* of simulated spatially resolved reflectance curves (ρ O (ρ*) denotes a decrease of the spatially resolved reflectance curve of 0.75 (2.4) orders of magnitude relative to the reflectance value at 1.2 mm). We found correlations between the curvature at ρ O and the reduced scattering coefficient as well as the slope at ρ* and the absorption coefficient. For the determination of the optical properties we used these two correlations. The calculation of the reduced scattering coefficient from the curvature at ρ O is practically independent from the absorption coefficient. Knowing the reduced scattering coefficient within a certain accuracy allows the determination of the absorption coefficient from the slope at ρ*. Additionally, we investigated the performance of an artificial neural network for the determination of the optical properties using the above explained correlations. This means we used the derivatives as input data. Our artificial neural network was capable to learn the mapping between the optical properties and the derivatives. In effect, the results for the determined optical properties improved in comparison to the above explained method. Finally, the procedure was compared to an artificial neural network that was trained without using the derivatives. (note)

A climatology of visible surface reflectance spectra

International Nuclear Information System (INIS)

Zoogman, Peter; Liu, Xiong; Chance, Kelly; Sun, Qingsong; Schaaf, Crystal; Mahr, Tobias; Wagner, Thomas

2016-01-01

We present a high spectral resolution climatology of visible surface reflectance as a function of wavelength for use in satellite measurements of ozone and other atmospheric species. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is planned to measure backscattered solar radiation in the 290–740 nm range, including the ultraviolet and visible Chappuis ozone bands. Observation in the weak Chappuis band takes advantage of the relative transparency of the atmosphere in the visible to achieve sensitivity to near-surface ozone. However, due to the weakness of the ozone absorption features this measurement is more sensitive to errors in visible surface reflectance, which is highly variable. We utilize reflectance measurements of individual plant, man-made, and other surface types to calculate the primary modes of variability of visible surface reflectance at a high spectral resolution, comparable to that of TEMPO (0.6 nm). Using the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirection Reflectance Distribution Function (BRDF)/albedo product and our derived primary modes we construct a high spatial resolution climatology of wavelength-dependent surface reflectance over all viewing scenes and geometries. The Global Ozone Monitoring Experiment–2 (GOME-2) Lambertian Equivalent Reflectance (LER) product provides complementary information over water and snow scenes. Preliminary results using this approach in multispectral ultraviolet+visible ozone retrievals from the GOME-2 instrument show significant improvement to the fitting residuals over vegetated scenes. - Highlights: • Our goals was visible surface reflectance for satellite trace gas measurements. • Captured the range of surface reflectance spectra through EOF analysis. • Used satellite surface reflectance products for each given scene to anchor EOFs. • Generated a climatology of time/geometry dependent surface reflectance spectra. • Demonstrated potential to

Parenting and Children's Externalizing Behavior: Bidirectionality during Toddlerhood

Science.gov (United States)

Verhoeven, Marjolein; Junger, Marianne; van Aken, Chantal; Dekovic, Maja; van Aken, Marcel A. G.

2010-01-01

This study examined the bidirectional relationship between parenting and boys' externalizing behaviors in a four-wave longitudinal study of toddlers. Participants were 104 intact two-parent families with toddler sons. When their sons were 17, 23, 29, and 35 months of age, mothers and fathers reported on a broad range of parenting dimensions…

A validation study of the psychometric properties of the Groningen Reflection Ability Scale

DEFF Research Database (Denmark)

Andersen, Nina Bjerre; O'Neill, Lotte; Gormsen, Lise Kirstine

2014-01-01

Background Reflection, the ability to examine critically one’s own learning and functioning, is considered important for ‘the good doctor’. The Groningen Reflection Ability Scale (GRAS) is an instrument measuring student reflection, which has not yet been validated beyond the original Dutch study....... The aim of this study was to adapt GRAS for use in a Danish setting and to investigate the psychometric properties of GRAS-DK. Methods We performed a cross-cultural adaptation of GRAS from Dutch to Danish. Next, we collected primary data online, performed a retest, analysed data descriptively, estimated...... measurement error, performed an exploratory and a confirmatory factor analysis to test the proposed three-factor structure. Results 361 (69%) of 523 invited students completed GRAS-DK. Their mean score was 88 (SD = 11.42; scale maximum 115). Scores were approximately normally distributed. Measurement error...

Geometrical considerations in analyzing isotropic or anisotropic surface reflections.

Science.gov (United States)

Simonot, Lionel; Obein, Gael

2007-05-10

The bidirectional reflectance distribution function (BRDF) represents the evolution of the reflectance with the directions of incidence and observation. Today BRDF measurements are increasingly applied and have become important to the study of the appearance of surfaces. The representation and the analysis of BRDF data are discussed, and the distortions caused by the traditional representation of the BRDF in a Fourier plane are pointed out and illustrated for two theoretical cases: an isotropic surface and a brushed surface. These considerations will help characterize either the specular peak width of an isotropic rough surface or the main directions of the light scattered by an anisotropic rough surface without misinterpretations. Finally, what is believed to be a new space is suggested for the representation of the BRDF, which avoids the geometrical deformations and in numerous cases is more convenient for BRDF analysis.

Cellular Mechanisms Underlying Behavioral State-Dependent Bidirectional Modulation of Motor Cortex Output

Directory of Open Access Journals (Sweden)

Julia Schiemann

2015-05-01

Full Text Available Neuronal activity in primary motor cortex (M1 correlates with behavioral state, but the cellular mechanisms underpinning behavioral state-dependent modulation of M1 output remain largely unresolved. Here, we performed in vivo patch-clamp recordings from layer 5B (L5B pyramidal neurons in awake mice during quiet wakefulness and self-paced, voluntary movement. We show that L5B output neurons display bidirectional (i.e., enhanced or suppressed firing rate changes during movement, mediated via two opposing subthreshold mechanisms: (1 a global decrease in membrane potential variability that reduced L5B firing rates (L5Bsuppressed neurons, and (2 a coincident noradrenaline-mediated increase in excitatory drive to a subpopulation of L5B neurons (L5Benhanced neurons that elevated firing rates. Blocking noradrenergic receptors in forelimb M1 abolished the bidirectional modulation of M1 output during movement and selectively impaired contralateral forelimb motor coordination. Together, our results provide a mechanism for how noradrenergic neuromodulation and network-driven input changes bidirectionally modulate M1 output during motor behavior.

Performance Analysis of Video PHY Controller Using Unidirection and Bi-directional IO Standard via 7 Series FPGA

DEFF Research Database (Denmark)

Das, Bhagwan; Abdullah, M F L; Hussain, Dil muhammed Akbar

2017-01-01

graphics consumes more power, this creates a need of designing the low power design for Video PHY controller. In this paper, the performance of Video PHY controller is analyzed by comparing the power consumption of unidirectional and bi-directional IO Standard over 7 series FPGA. It is determined...... that total on-chip power is reduced for unidirectional IO Standard based Video PHY controller compared to bidirectional IO Standard based Video PHY controller. The most significant achievement of this work is that it is concluded that unidirectional IO Standard based Video PHY controller consume least...... standby power compared to bidirectional IO Standard based Video PHY controller. It is defined that for 6 GHz operated frequency Video PHY controller, the 32% total on-chip power is reduced using unidirectional IO Standard based Video PHY controller is less compared to bidirectional IO Standard based Video...

Measurement and modelization of silica opal reflection properties: Optical determination of the silica index

Science.gov (United States)

Avoine, Amaury; Hong, Phan Ngoc; Frederich, Hugo; Frigerio, Jean-Marc; Coolen, Laurent; Schwob, Catherine; Nga, Pham Thu; Gallas, Bruno; Maître, Agnès

2012-10-01

Self-assembled artificial opals (in particular silica opals) constitute a model system to study the optical properties of three-dimensional photonic crystals. The silica optical index is a key parameter to correctly describe an opal but is difficult to measure at the submicrometer scale and usually treated as a free parameter. Here, we propose a method to extract the silica index from the opal reflection spectra and we validate it by comparison with two independent methods based on infrared measurements. We show that this index gives a correct description of the opal reflection spectra, either by a band structure or by a Bragg approximation. In particular, we are able to provide explanations in quantitative agreement with the measurements for two features : the observation of a second reflection peak in specular direction, and the quasicollapse of the p-polarized main reflection peak at a typical angle of 54∘.

Bidirectional Barbed Sutures for Wound Closure: Evolution and Applications

Science.gov (United States)

Paul, Malcolm D.

2009-01-01

Traditionally, wound closure sutures have in common the need to tie knots with the inherent risk of extrusion, palpability, microinfarcts, breakage, and slippage. Bidirectional barbed sutures have barbs arrayed in a helical fashion in opposing directions on either side of an unbarbed midsegment. This suture is inserted at the midpoint of a wound and pulled through till resistance is encountered from the opposing barbs; each half of the suture is then advanced to the lateral ends of the wound. This design provides a method of evenly distributing tension along the incision line, a faster suture placement and closure time with no need to tie knots, and the possibility of improved cosmesis. Bidirectional barbed sutures, which are available in both absorbable and nonabsorbable forms, can be used for simple closures, multilayered closures, and closure of high-tension wounds in a variety of surgical settings. PMID:24527114

Pore structures and mechanical properties of porous titanium scaffolds by bidirectional freeze casting.

Science.gov (United States)

Yan, Leiming; Wu, Jisi; Zhang, Lei; Liu, Xinli; Zhou, Kechao; Su, Bo

2017-06-01

Porous titanium scaffolds with long-range lamellar structure were fabricated using a novel bidirectional freeze casting method. Compared with the ordinarily porous titanium materials made by traditional freeze casting, the titanium walls can offer the structure of ordered arrays with parallel to each other in the transverse cross-sections. And titanium scaffolds with different pore width, wall size and porosity can be synthesized in terms of adjusting the fabrication parameters. As the titanium content was increased from 15vol.% to 25vol.%, the porosity and pore width decreased from 67±3% to 50±2% and 80±10μm to 67±7μm, respectively. On the contrary, as the wall size was increased from 18±2μm to 30±3μm, the compressive strength and stiffness were increased from 58±8MPa to 162±10MPa and from 2.5±0.7GPa to 6.5±0.9GPa, respectively. The porous titanium scaffolds with long-range lamellar structure and controllable pore structure produced in present work will be capable of having potential application as bone tissue scaffold materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Primary Parallel Isolated Boost Converter with Bidirectional Operation

DEFF Research Database (Denmark)

Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gökhan

2012-01-01

This paper presents a bidirectional dc/dc converter operated with batteries both in the input and output. Primary parallel isolated boost converter (PPIBC) with transformer series connection on the high voltage side is preferred due to its ability to handle high currents in the low voltage side. ...... and output battery banks with a defined ramp....

Bidirectional Relationships Between Parenting Processes and Deviance in a Sample of Inner-City African American Youth

Science.gov (United States)

Harris, Charlene; Vazsonyi, Alexander T.; Bolland, John M.

2016-01-01

The current study assessed for bidirectional relationships among supportive parenting (knowledge), negative parenting (permissiveness), and deviance in a sample (N = 5,325) of poor, inner-city African American youth from the Mobile Youth Survey (MYS) over 4 years. Cross-lagged path analysis provided evidence of significant bidirectional paths among parenting processes (knowledge and permissiveness) and deviance over time. Follow-up multigroup tests provided only modest evidence of dissimilar relationships by sex and by developmental periods. The findings improve our understanding of developmental changes between parenting behaviors and deviance during adolescence and extended current research of the bidirectionality of parent and child relationships among inner-city African American youth. PMID:28316460

Analysis of Bi-directional Effects on the Response of a Seismic Base Isolation System

International Nuclear Information System (INIS)

Park, Hyung-Kui; Kim, Jung-Han; Kim, Min Kyu; Choi, In-Kil

2014-01-01

The floor response spectrum depends on the height of the floor of the structure. Also FRS depends on the characteristics of the seismic base isolation system such as the natural frequency, damping ratio. In the previous study, the floor response spectrum of the base isolated structure was calculated for each axis without considering bi-directional effect. However, the shear behavior of the seismic base isolation system of two horizontal directions are correlated each other by the bi-directional effects. If the shear behavior of the seismic isolation system changes, it can influence the floor response spectrum and displacement response of isolators. In this study, the analysis of a bi-directional effect on the floor response spectrum was performed. In this study, the response of the seismic base isolation system based on the bi-directional effects was analyzed. By analyzing the time history result, while there is no alteration in the maximum shear force of seismic base isolation system, it is confirmed that the shear force is generally more decreased in a one-directional that in a two-directional in most parts. Due to the overall decreased shear force, the floor response spectrum is more reduced in a two-directional than in a one-directional

Bidirectional current-voltage converters based on magnetostrictive/piezoelectric composites

NARCIS (Netherlands)

Jia, Y.; Or, S.W.; Chan, H.L.W.; Jiao, J.; Luo, H.; Van der Zwaag, S.

2009-01-01

We report a power supply-free, bidirectional electric current-voltage converter based on a coil-wound laminated composite of magnetostrictive alloy and piezoelectric crystal. An electric current applied to the coil induces a magnetic field, resulting in an electric voltage from the composite due to

Isolated Bidirectional DC–DC Converter for SuperCapacitor Applications

DEFF Research Database (Denmark)

Dehnavi, Sayed M. D.; Sen, Gökhan; Thomsen, Ole Cornelius

2011-01-01

This paper proposes a new bidirectional DC/DC converter for supercapacitor applications. The proposed converter has a parallel structure in supercapacitor side (where voltage is low and current is high) and a series structure in the other side. This structure increases efficiency of the converter...

Deadbeat control of power leveling unit with bidirectional buck/boost DC/DC converter

OpenAIRE

Hamasaki, Shin-ichi; Mukai, Ryosuke; Yano, Yoshihiro; Tsuji, Mineo

2014-01-01

As a distributed generation system increases, a stable power supply becomes difficult. Thus control of power leveling (PL) unit is required to maintain the balance of power flow for irregular power generation. The unit is required to respond to change of voltage and bidirectional power flow. So the bidirectional buck/boost DC/DC converter is applied for the control of PL unit in this research. The PL unit with Electric double-layer capacitor (EDLC) is able to absorb change of power, and it is...

Finite-Time Stability for Fractional-Order Bidirectional Associative Memory Neural Networks with Time Delays

International Nuclear Information System (INIS)

Xu Chang-Jin; Li Pei-Luan; Pang Yi-Cheng

2017-01-01

This paper is concerned with fractional-order bidirectional associative memory (BAM) neural networks with time delays. Applying Laplace transform, the generalized Gronwall inequality and estimates of Mittag–Leffler functions, some sufficient conditions which ensure the finite-time stability of fractional-order bidirectional associative memory neural networks with time delays are obtained. Two examples with their simulations are given to illustrate the theoretical findings. Our results are new and complement previously known results. (paper)

Measurement of sugar content of watermelon using near-infrared reflectance spectroscopy in comparison with dielectric property

Science.gov (United States)

Tao, Xuemei; Bao, Yidan

2006-09-01

The sugar content of watermelon is important to its taste thus influences the market. It's difficult to know whether the melon is sweet or not for consumers. We tried to develop a convenient meter to determine the sugar of watermelon. The first objective of this paper was to demonstrate the feasibility of using a near-infrared reflectance spectrometer (NIRS) to investigate the relationship between sugar content of watermelon and absorption spectra. The NIRS reflectance of nondestructive watermelon was measured with a Visible/NIR spectrophotometer in 325-1075nm range. The sugar content of watermelon was obtained with a handhold sugar content meter. The second objective was to measure the watermelon's dielectric property, such as dielectric resistance, capacitance, quality factor and dielectric loss. A digital electric bridge instrument was used to get the dielectric property. The experimental results show that they were related to watermelon's sugar content. A comparison between the two methods was made in the paper. The model derived from NIRS reflection is useful for class identification of Zaochun Hongyu watermelon though it's not quite accurate in sweetness prediction (the max. deviation is 0.7). Electric property bears little relation to sugar content of watermelon at this experiment and it couldn't be used as non-destructive inspection method.

Influence of diffuse reflectance measurement accuracy on the scattering coefficient in determination of optical properties with integrating sphere optics (a secondary publication).

Science.gov (United States)

Horibe, Takuro; Ishii, Katsunori; Fukutomi, Daichi; Awazu, Kunio

2015-12-30

An estimation error of the scattering coefficient of hemoglobin in the high absorption wavelength range has been observed in optical property calculations of blood-rich tissues. In this study, the relationship between the accuracy of diffuse reflectance measurement in the integrating sphere and calculated scattering coefficient was evaluated with a system to calculate optical properties combined with an integrating sphere setup and the inverse Monte Carlo simulation. Diffuse reflectance was measured with the integrating sphere using a small incident port diameter and optical properties were calculated. As a result, the estimation error of the scattering coefficient was improved by accurate measurement of diffuse reflectance. In the high absorption wavelength range, the accuracy of diffuse reflectance measurement has an effect on the calculated scattering coefficient.

Protein remote homology detection based on bidirectional long short-term memory.

Science.gov (United States)

Li, Shumin; Chen, Junjie; Liu, Bin

2017-10-10

Protein remote homology detection plays a vital role in studies of protein structures and functions. Almost all of the traditional machine leaning methods require fixed length features to represent the protein sequences. However, it is never an easy task to extract the discriminative features with limited knowledge of proteins. On the other hand, deep learning technique has demonstrated its advantage in automatically learning representations. It is worthwhile to explore the applications of deep learning techniques to the protein remote homology detection. In this study, we employ the Bidirectional Long Short-Term Memory (BLSTM) to learn effective features from pseudo proteins, also propose a predictor called ProDec-BLSTM: it includes input layer, bidirectional LSTM, time distributed dense layer and output layer. This neural network can automatically extract the discriminative features by using bidirectional LSTM and the time distributed dense layer. Experimental results on a widely-used benchmark dataset show that ProDec-BLSTM outperforms other related methods in terms of both the mean ROC and mean ROC50 scores. This promising result shows that ProDec-BLSTM is a useful tool for protein remote homology detection. Furthermore, the hidden patterns learnt by ProDec-BLSTM can be interpreted and visualized, and therefore, additional useful information can be obtained.

Troubling Muddy Waters: Problematizing Reflective Practice in Global Medical Education.

Science.gov (United States)

Naidu, Thirusha; Kumagai, Arno K

2016-03-01

The idea of exporting the concept of reflective practice for a global medical education audience is growing. However, the uncritical export and adoption of Western concepts of reflection may be inappropriate in non-Western societies. The emphasis in Western medical education on the use of reflection for a specific end--that is, the improvement of individual clinical practice--tends to ignore the range of reflective practice, concentrating on reflection alone while overlooking critical reflection and reflexivity. This Perspective places the concept of reflective practice under a critical lens to explore a broader view for its application in medical education outside the West. The authors suggest that ideas about reflection in medicine and medical education may not be as easily transferable from Western to non-Western contexts as concepts from biomedical science are. The authors pose the question, When "exporting" Western medical education strategies and principles, how often do Western-trained educators authentically open up to the possibility that there are alternative ways of seeing and knowing that may be valuable in educating Western physicians? One answer lies in the assertion that educators should aspire to turn exportation of educational theory into a truly bidirectional, collaborative exchange in which culturally conscious views of reflective practice contribute to humanistic, equitable patient care. This discussion engages in troubling the already-muddy waters of reflective practice by exploring the global applicability of reflective practice as it is currently applied in medical education. The globalization of medical education demands critical reflection on reflection itself.

The multispectral reflectance of shortwave radiation by agricultural crops in relation with their morphological and optical properties

NARCIS (Netherlands)

Bunnik, N.J.J.

1978-01-01

Relations between morphological properties of uniform canopies. optical properties of the leaves and reflection of shortwave radiation, in the visible light region and the near infrared, by crops are the subject of this thesis.

The aim of the study was a further investigation of

High-efficiency dual-modes vortex beam generator with polarization-dependent transmission and reflection properties.

Science.gov (United States)

Tang, Shiwei; Cai, Tong; Wang, Guang-Ming; Liang, Jian-Gang; Li, Xike; Yu, Jiancheng

2018-04-23

Vortex beam is believed to be an effective way to extend communication capacity, but available efforts suffer from the issues of complex configurations, fixed operation mode as well as low efficiency. Here, we propose a general strategy to design dual-modes vortex beam generator by using metasurfaces with polarization-dependent transmission and reflection properties. Combining the focusing and vortex functionalities, we design/fabricate a type of compact dual-modes vortex beam generator operating at both reflection/transmission sides of the system. Experimental results demonstrate that the designed metadevice can switch freely and independently between the reflective vortex with topological charge m 1  = 2 and transmissive vortex with m 2  = 1. Moreover, the metadevice exhibits very high efficiencies of 91% and 85% for the reflective and transmissive case respectively. Our findings open a door for multifunctional metadevices with high performances, which indicate wide applications in modern integration-optics and wireless communication systems.

Remote measurement of surface roughness, surface reflectance, and body reflectance with LiDAR.

Science.gov (United States)

Li, Xiaolu; Liang, Yu

2015-10-20

Light detection and ranging (LiDAR) intensity data are attracting increasing attention because of the great potential for use of such data in a variety of remote sensing applications. To fully investigate the data potential for target classification and identification, we carried out a series of experiments with typical urban building materials and employed our reconstructed built-in-lab LiDAR system. Received intensity data were analyzed on the basis of the derived bidirectional reflectance distribution function (BRDF) model and the established integration method. With an improved fitting algorithm, parameters involved in the BRDF model can be obtained to depict the surface characteristics. One of these parameters related to surface roughness was converted to a most used roughness parameter, the arithmetical mean deviation of the roughness profile (Ra), which can be used to validate the feasibility of the BRDF model in surface characterizations and performance evaluations.

Longitudinal Bidirectional Relations between Adolescents' Sympathy and Prosocial Behavior

Science.gov (United States)

Carlo, Gustavo; Padilla-Walker, Laura M.; Nielson, Matthew G.

2015-01-01

Despite the importance of understanding sympathy and prosocial behaviors, research on the development of these tendencies in adolescence remains relatively sparse. In the present study, we examined age trends and bidirectional longitudinal relations in sympathy and prosocial behaviors across early to middle adolescents. Participants were 500…

Directional radiative properties of anisotropic rough silicon and gold surfaces

Energy Technology Data Exchange (ETDEWEB)

Lee, H.J.; Chen, Y.B.; Zhang, Z.M. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

2006-11-15

Recent studies have shown that the topography of some chemically etched microrough silicon surfaces is non-Gaussian and may be strongly anisotropic. However, the bidirectional reflectance distribution function (BRDF) of anisotropic surfaces has not been fully understood. The present study uses the Monte Carlo method to investigate the out-of-plane BRDF, multiple scattering, and the change of the polarization state upon reflection. Two ray-tracing algorithms are developed that incorporate the surface topography or slope distribution of the samples obtained by the use of an atomic force microscope. The predicted BRDFs for silicon surfaces with or without a gold coating are in reasonable agreement with the results measured using a laser scatterometer at a wavelength of 635nm. The employment of surface topographic data is indispensable to the BRDF modeling of anisotropic surfaces. While first-order scattering makes the dominant contribution to reflections from the studied surfaces, it is critical to consider the polarization state change in order to correctly predict the out-of-plane BRDF. The versatile Monte Carlo modeling tools developed through the present study help gain a better understanding of the directional radiative properties of microrough surfaces and, furthermore, will have an impact on thermal metrology in the semiconductor industry. (author)

A Bidirectional Relationship between Conceptual Organization and Word Learning

Directory of Open Access Journals (Sweden)

Tanya Kaefer

2013-01-01

Full Text Available This study explores the relationship between word learning and conceptual organization for preschool-aged children. We proposed a bidirectional model in which increases in word learning lead to increases in taxonomic organization, which, in turn, leads to further increases in word learning. In order to examine this model, we recruited 104 4-year olds from Head Start classrooms; 52 children participated in a two-week training program, and 52 children were in a control group. Results indicated that children in the training program learned more words and were more likely to sort taxonomically than children in the control condition. Furthermore, the number of words learned over the training period predicted the extent to which children categorized taxonomically. Additionally, this ability to categorize taxonomically predicted the number of words learned outside the training program, over and above the number of words learned in the program. These results suggest a bi-directional relationship between conceptual organization and word learning.

Bidirectional magnetic microactuators for uTAS

Science.gov (United States)

Hilbich, Daniel D.; Khosla, Ajit; Gray, Bonnie L.; Shannon, Lesley

2011-02-01

We present the design, fabrication and characterization of a novel bidirectional magnetic microactuator. The actuator has a planar structure and is easily fabricated using processes based on laser micromachining and soft lithography, allowing it to be readily integrated into microfluidic, microelectromechanical systems (MEMS) and lab-on-a-chip (LOC) designs. The new microactuator is a thin magnetic membrane with a central magnet feature. The membrane and magnet are both composed of a magnetic nanocomposite polymer (M-NCP) material that is fabricated by embedding magnetic powder in a polydimethysiloxane (PDMS) polymer matrix. The magnetic powder (MQP-12-5) has the chemical composition of (Nd0.7Ce0.3)10.5Fe83.9B5.6, and contains grains that are 5-6 microns in size. The powder is uniformly dispersed at a weight percentage of 75 wt-% in the PDMS matrix, and micropatterned using soft lithography micromolding to realize magnetic microstructures, which sit on a thinner magnetic PDMS membrane of the same material. The molds are fabricated by laser-etching into Poly (methyl methacrylate) (PMMA) using a Universal Laser System's VersaLASERlaser ablation system. The PDMS-based M-NCP is then poured and spun over the mold patterns, producing a thin polymer membrane to which the polymer micromagnets are attached, forming a one-piece actuator. The M-NCP is initially un-magnetized, but is then magnetized by placing it in a 2.5T magnetic field to produce permanent bidirectional magnetization that is polarized in the specified direction. To characterize the bidirectional actuators, a uniform magnetic field is established via a Helmholtz coil pair, and is characterized by applying varying currents. The magnetic field (and thus the actuator deflection) is controlled by regulating the current in the Helmholtz pair. Using this apparatus, deflection versus field characteristics are obtained, with maximum deflections varying as a function of actuator dimensions and the applied magnetic

Bidirectional effects between parenting and aggressive child behavior in the context of a preventive intervention

OpenAIRE

Brinke, L.W. te; Dekovic, M.; Stoltz, S.E.M.J.; Cillessen, A.H.N.

2017-01-01

Over time, developmental theories and empirical studies have gradually started to adopt a bidirectional viewpoint. The area of intervention research is, however, lagging behind in this respect. This longitudinal study examined whether bidirectional associations between (changes in) parenting and (changes in) aggressive child behavior over time differed in three conditions: a child intervention condition, a child + parent intervention condition and a control condition. Participants were 267 ch...

Bidirectional Telemetry Controller for Neuroprosthetic Devices

Science.gov (United States)

Sharma, Vishnu; McCreery, Douglas B.; Han, Martin; Pikov, Victor

2010-01-01

We present versatile multifunctional programmable controller with bidirectional data telemetry, implemented using existing commercial microchips and standard Bluetooth protocol, which adds convenience, reliability, and ease-of-use to neuroprosthetic devices. Controller, weighing 190 g, is placed on animal's back and provides bidirectional sustained telemetry rate of 500 kb/s, allowing real-time control of stimulation parameters and viewing of acquired data. In continuously-active state, controller consumes ∼420 mW and operates without recharge for 8 h. It features independent 16-channel current-controlled stimulation, allowing current steering; customizable stimulus current waveforms; recording of stimulus voltage waveforms and evoked neuronal responses with stimulus artifact blanking circuitry. Flexibility, scalability, cost-efficiency, and a user-friendly computer interface of this device allow use in animal testing for variety of neuroprosthetic applications. Initial testing of the controller has been done in a feline model of brainstem auditory prosthesis. In this model, the electrical stimulation is applied to the array of microelectrodes implanted in the ventral cochlear nucleus, while the evoked neuronal activity was recorded with the electrode implanted in the contralateral inferior colliculus. Stimulus voltage waveforms to monitor the access impedance of the electrodes were acquired at the rate of 312 kilosamples/s. Evoked neuronal activity in the inferior colliculus was recorded after the blanking (transient silencing) of the recording amplifier during the stimulus pulse, allowing the detection of neuronal responses within 100 μs after the end of the stimulus pulse applied in the cochlear nucleus. PMID:19933010

Bidirectional telemetry controller for neuroprosthetic devices.

Science.gov (United States)

Sharma, Vishnu; McCreery, Douglas B; Han, Martin; Pikov, Victor

2010-02-01

We present versatile multifunctional programmable controller with bidirectional data telemetry, implemented using existing commercial microchips and standard Bluetooth protocol, which adds convenience, reliability, and ease-of-use to neuroprosthetic devices. Controller, weighing 190 g, is placed on animal's back and provides bidirectional sustained telemetry rate of 500 kb/s , allowing real-time control of stimulation parameters and viewing of acquired data. In continuously-active state, controller consumes approximately 420 mW and operates without recharge for 8 h . It features independent 16-channel current-controlled stimulation, allowing current steering; customizable stimulus current waveforms; recording of stimulus voltage waveforms and evoked neuronal responses with stimulus artifact blanking circuitry. Flexibility, scalability, cost-efficiency, and a user-friendly computer interface of this device allow use in animal testing for variety of neuroprosthetic applications. Initial testing of the controller has been done in a feline model of brainstem auditory prosthesis. In this model, the electrical stimulation is applied to the array of microelectrodes implanted in the ventral cochlear nucleus, while the evoked neuronal activity was recorded with the electrode implanted in the contralateral inferior colliculus. Stimulus voltage waveforms to monitor the access impedance of the electrodes were acquired at the rate of 312 kilosamples/s. Evoked neuronal activity in the inferior colliculus was recorded after the blanking (transient silencing) of the recording amplifier during the stimulus pulse, allowing the detection of neuronal responses within 100 mus after the end of the stimulus pulse applied in the cochlear nucleus.

Bidirectional Prospective Associations between Cardiac Autonomic Activity and Inflammatory Markers

NARCIS (Netherlands)

Hu, Mandy X; Lamers, Femke; Neijts, Melanie; Willemsen, Gonneke; de Geus, Eco J C; Penninx, Brenda W J H

2018-01-01

OBJECTIVE: Autonomic nervous system (ANS) imbalance has been cross-sectionally associated with inflammatory processes. Longitudinal studies are needed to shed light on the nature of this relationship. We examined cross-sectional and bidirectional prospective associations between cardiac autonomic

Bidirectional Associations Between Adolescents' Sexual Behaviors and Psychological Well-Being

NARCIS (Netherlands)

Nogueira Avelar e Silva, Raquel; van de Bongardt, Daphne; Baams, Laura; Raat, Hein

Purpose: Assessing bidirectional longitudinal associations between early sexual behaviors (≤16.0 years) and psychological well-being (global self-esteem, physical self-esteem, depression) among 716 adolescents, and the direct and buffering effect of parent-adolescent relationship quality. Methods:

Hyperspectral diffuse reflectance for determination of the optical properties of milk and fruit and vegetable juices

Science.gov (United States)

Qin, Jianwei; Lu, Renfu

2005-11-01

Absorption and reduced scattering coefficients are two fundamental optical properties for turbid biological materials. This paper presents the technique and method of using hyperspectral diffuse reflectance for fast determination of the optical properties of fruit and vegetable juices and milks. A hyperspectral imaging system was used to acquire spatially resolved steady-state diffuse reflectance over the spectral region between 530 and 900 nm from a variety of fruit and vegetable juices (citrus, grapefruit, orange, and vegetable) and milks with different fat levels (full, skim and mixed). The system collected diffuse reflectance in the source-detector separation range from 1.1 to 10.0 mm. The hyperspectral reflectance data were analyzed by using a diffusion theory model for semi-infinite homogeneous media. The absorption and reduced scattering coefficients of the fruit and vegetable juices and milks were extracted by inverse algorithms from the scattering profiles for wavelengths of 530-900 nm. Values of the absorption and reduced scattering coefficient at 650 nm were highly correlated to the fat content of the milk samples with the correlation coefficient of 0.990 and 0.989, respectively. The hyperspectral imaging technique can be extended to the measurement of other liquid and solid foods in which light scattering is dominant.

Properties of interstellar dust in reflection nebulae

International Nuclear Information System (INIS)

Sellgren, K.

1988-01-01

Observations of interstellar dust in reflection nebulae are the closest analog in the interstellar medium to studies of cometary dust in our solar system. The presence of a bright star near the reflection nebula dust provides the opportunity to study both the reflection and emission characteristics of interstellar dust. At 0.1 to 1 micrometer, the reflection nebula emission is due to starlight scattered by dust. The albedo and scattering phase function of the dust is determined from observations of the scattered light. At 50 to 200 micrometers, thermal emission from the dust in equilibrium with the stellar radiation field is observed. The derived dust temperature determines the relative values of the absorption coefficient of the dust at wavelengths where the stellar energy is absorbed and at far infrared wavelengths where the absorbed energy is reradiated. These emission mechanisms directly relate to those seen in the near and mid infrared spectra of comets. In a reflection nebula the dust is observed at much larger distances from the star than in our solar system, so that the equilibrium dust temperature is 50 K rather than 300 K. Thus, in reflection nebulae, thermal emission from dust is emitted at 50 to 200 micrometer

Photometric properties of Mars soils analogs

Science.gov (United States)

Pommerol, A.; Thomas, N.; Jost, B.; Beck, P.; Okubo, C.; McEwen, A.S.

2013-01-01

We have measured the bidirectional reflectance of analogs of dry, wet, and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples to investigate the effects of surface texture. Comparisons with results independently obtained by different teams with similar samples showed a satisfying reproducibility of the photometric measurements as well as a noticeable influence of surface textures resulting from different sample preparation procedures. In a second step, water was introduced to produce wet and frozen samples and their photometry investigated. Optical microscope images of the samples provided information about their microtexture. Liquid water, even in relatively low amount, resulted in the disappearance of the backscattering peak and the appearance of a forward-scattering peak whose intensity increases with the amount of water. Specular reflections only appeared when water was present in an amount large enough to allow water to form a film at the surface of the sample. Icy samples showed a wide variability of photometric properties depending on the physical properties of the water ice. We discuss the implications of these measurements in terms of the expected photometric behavior of the Martian surface, from equatorial to circum-polar regions. In particular, we propose some simple photometric criteria to improve the identification of wet and/or icy soils from multiple observations under different geometries.

ENERGY-EFFICIENT PASSIVE ANTENNA CODE PULSE MODULATION DUE TO THE REFLECTION OF MICROWAVE SIGNAL

Directory of Open Access Journals (Sweden)

T. A. Ismailov

2015-01-01

Full Text Available The article describes an antenna in a corner reflector with a p-i-n-diodes, integrated with the housing transceiver, which allows not only to provide bidirectional communication with the base station as a result of multipath radio three times, but with minimal energy consumption to provide digitally transmit information on the reflected wave flow of any complexity, which allow to eliminate energy in the transmit path and extend the life of the device. 

Connecting Neurons to a Mobile Robot: An In Vitro Bidirectional Neural Interface

Directory of Open Access Journals (Sweden)

A. Novellino

2007-01-01

Full Text Available One of the key properties of intelligent behaviors is the capability to learn and adapt to changing environmental conditions. These features are the result of the continuous and intense interaction of the brain with the external world, mediated by the body. For this reason x201C;embodiment” represents an innovative and very suitable experimental paradigm when studying the neural processes underlying learning new behaviors and adapting to unpredicted situations. To this purpose, we developed a novel bidirectional neural interface. We interconnected in vitro neurons, extracted from rat embryos and plated on a microelectrode array (MEA, to external devices, thus allowing real-time closed-loop interaction. The novelty of this experimental approach entails the necessity to explore different computational schemes and experimental hypotheses. In this paper, we present an open, scalable architecture, which allows fast prototyping of different modules and where coding and decoding schemes and different experimental configurations can be tested. This hybrid system can be used for studying the computational properties and information coding in biological neuronal networks with far-reaching implications for the future development of advanced neuroprostheses.

Reflection ciphers

DEFF Research Database (Denmark)

Boura, Christina; Canteaut, Anne; Knudsen, Lars Ramkilde

2017-01-01

study the necessary properties for this coupling permutation. Special care has to be taken of some related-key distinguishers since, in the context of reflection ciphers, they may provide attacks in the single-key setting.We then derive some criteria for constructing secure reflection ciphers...

Cross-species mapping of bidirectional promoters enables prediction of unannotated 5' UTRs and identification of species-specific transcripts

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Lewin Harris A

2009-04-01

Full Text Available Abstract Background Bidirectional promoters are shared regulatory regions that influence the expression of two oppositely oriented genes. This type of regulatory architecture is found more frequently than expected by chance in the human genome, yet many specifics underlying the regulatory design are unknown. Given that the function of most orthologous genes is similar across species, we hypothesized that the architecture and regulation of bidirectional promoters might also be similar across species, representing a core regulatory structure and enabling annotation of these regions in additional mammalian genomes. Results By mapping the intergenic distances of genes in human, chimpanzee, bovine, murine, and rat, we show an enrichment for pairs of genes equal to or less than 1,000 bp between their adjacent 5' ends ("head-to-head" compared to pairs of genes that fall in the same orientation ("head-to-tail" or whose 3' ends are side-by-side ("tail-to-tail". A representative set of 1,369 human bidirectional promoters was mapped to orthologous sequences in other mammals. We confirmed predictions for 5' UTRs in nine of ten manual picks in bovine based on comparison to the orthologous human promoter set and in six of seven predictions in human based on comparison to the bovine dataset. The two predictions that did not have orthology as bidirectional promoters in the other species resulted from unique events that initiated transcription in the opposite direction in only those species. We found evidence supporting the independent emergence of bidirectional promoters from the family of five RecQ helicase genes, which gained their bidirectional promoters and partner genes independently rather than through a duplication process. Furthermore, by expanding our comparisons from pairwise to multispecies analyses we developed a map representing a core set of bidirectional promoters in mammals. Conclusion We show that the orthologous positions of bidirectional

Bidirectional Dynamic Diversity Evolutionary Algorithm for Constrained Optimization

Directory of Open Access Journals (Sweden)

Weishang Gao

2013-01-01

Full Text Available Evolutionary algorithms (EAs were shown to be effective for complex constrained optimization problems. However, inflexible exploration-exploitation and improper penalty in EAs with penalty function would lead to losing the global optimum nearby or on the constrained boundary. To determine an appropriate penalty coefficient is also difficult in most studies. In this paper, we propose a bidirectional dynamic diversity evolutionary algorithm (Bi-DDEA with multiagents guiding exploration-exploitation through local extrema to the global optimum in suitable steps. In Bi-DDEA potential advantage is detected by three kinds of agents. The scale and the density of agents will change dynamically according to the emerging of potential optimal area, which play an important role of flexible exploration-exploitation. Meanwhile, a novel double optimum estimation strategy with objective fitness and penalty fitness is suggested to compute, respectively, the dominance trend of agents in feasible region and forbidden region. This bidirectional evolving with multiagents can not only effectively avoid the problem of determining penalty coefficient but also quickly converge to the global optimum nearby or on the constrained boundary. By examining the rapidity and veracity of Bi-DDEA across benchmark functions, the proposed method is shown to be effective.

Mechanical and abrasive wear characterization of bidirectional and chopped E-glass fiber reinforced composite materials

International Nuclear Information System (INIS)

Siddhartha,; Gupta, Kuldeep

2012-01-01

Highlights: ► Bi-directional and chopped E-glass fiber reinforced epoxy composites are fabricated. ► Three body abrasive wear behavior of fabricated composites has been assessed. ► Results are validated against existing microscopic models of Lancaster and Wang. ► Tensile strength of bi-directional E-glass fiber reinforced composites increases. ► Chopped glass fiber composites are found better in abrasive wear situations. -- Abstract: Bi-directional and chopped E-glass fiber reinforced epoxy composites are fabricated in five different (15, 20, 25, 30 and 35) wt% in an epoxy resin matrix. The mechanical characterization of these composites is performed. The three body abrasive wear behavior of fabricated composites has been assessed under different operating conditions. Abrasive wear characteristics of these composites are successfully analysed using Taguchi’s experimental design scheme and analysis of variance (ANOVA). The results obtained from these experiments are also validated against existing microscopic models of Ratner-Lancaster and Wang. It is observed that quite good linear relationships is held between specific wear rate and reciprocal of ultimate strength and strain at tensile fracture of these composites which is an indicative that the experimental results are in fair agreement with these existing models. Out of all composites fabricated it is found that tensile strength of bi-directional E-glass fiber reinforced composites increases because of interface strength enhancement. Chopped glass fiber reinforced composites are observed to perform better than bi-directional glass fiber reinforced composites under abrasive wear situations. The morphology of worn composite specimens has been examined by scanning electron microscopy (SEM) to understand about dominant wear mechanisms.

Bidirectional Associations Between Externalizing Behavior Problems and Maladaptive Parenting Within Parent-Son Dyads Across Childhood.

Science.gov (United States)

Besemer, Sytske; Loeber, Rolf; Hinshaw, Stephen P; Pardini, Dustin A

2016-10-01

Coercive parent-child interaction models posit that an escalating cycle of negative, bidirectional interchanges influences the development of boys' externalizing problems and caregivers' maladaptive parenting over time. However, longitudinal studies examining this hypothesis have been unable to rule out the possibility that between-individual factors account for bidirectional associations between child externalizing problems and maladaptive parenting. Using a longitudinal sample of boys (N = 503) repeatedly assessed eight times across 6-month intervals in childhood (in a range between 6 and 13 years), the current study is the first to use novel within-individual change (fixed effects) models to examine whether parents tend to increase their use of maladaptive parenting strategies following an increase in their son's externalizing problems, or vice versa. These bidirectional associations were examined using multiple facets of externalizing problems (i.e., interpersonal callousness, conduct and oppositional defiant problems, hyperactivity/impulsivity) and parenting behaviors (i.e., physical punishment, involvement, parent-child communication). Analyses failed to support the notion that when boys increase their typical level of problem behaviors, their parents show an increase in their typical level of maladaptive parenting across the subsequent 6 month period, and vice versa. Instead, across 6-month intervals, within parent-son dyads, changes in maladaptive parenting and child externalizing problems waxed and waned in concert. Fixed effects models to address the topic of bidirectional relations between parent and child behavior are severely underrepresented. We recommend that other researchers who have found significant bidirectional parent-child associations using rank-order change models reexamine their data to determine whether these findings hold when examining changes within parent-child dyads.

Reward-timing-dependent bidirectional modulation of cortical microcircuits during optical single-neuron operant conditioning.

Science.gov (United States)

Hira, Riichiro; Ohkubo, Fuki; Masamizu, Yoshito; Ohkura, Masamichi; Nakai, Junichi; Okada, Takashi; Matsuzaki, Masanori

2014-11-24

Animals rapidly adapt to environmental change. To reveal how cortical microcircuits are rapidly reorganized when an animal recognizes novel reward contingency, we conduct two-photon calcium imaging of layer 2/3 motor cortex neurons in mice and simultaneously reinforce the activity of a single cortical neuron with water delivery. Here we show that when the target neuron is not relevant to a pre-trained forelimb movement, the mouse increases the target neuron activity and the number of rewards delivered during 15-min operant conditioning without changing forelimb movement behaviour. The reinforcement bidirectionally modulates the activity of subsets of non-target neurons, independent of distance from the target neuron. The bidirectional modulation depends on the relative timing between the reward delivery and the neuronal activity, and is recreated by pairing reward delivery and photoactivation of a subset of neurons. Reward-timing-dependent bidirectional modulation may be one of the fundamental processes in microcircuit reorganization for rapid adaptation.

Bidirectional automatic release of reserve for low voltage network made with low capacity PLCs

Science.gov (United States)

Popa, I.; Popa, G. N.; Diniş, C. M.; Deaconu, S. I.

2018-01-01

The article presents the design of a bidirectional automatic release of reserve made on two types low capacity programmable logic controllers: PS-3 from Klöckner-Moeller and Zelio from Schneider. It analyses the electronic timing circuits that can be used for making the bidirectional automatic release of reserve: time-on delay circuit and time-off delay circuit (two types). In the paper are present the sequences code for timing performed on the PS-3 PLC, the logical functions for the bidirectional automatic release of reserve, the classical control electrical diagram (with contacts, relays, and time relays), the electronic control diagram (with logical gates and timing circuits), the code (in IL language) made for the PS-3 PLC, and the code (in FBD language) made for Zelio PLC. A comparative analysis will be carried out on the use of the two types of PLC and will be present the advantages of using PLCs.

Studi Komparasi Fungsi Keanggotaan Fuzzy sebagai Kontroler Bidirectional DC-DC Converter pada Sistem Penyimpan Energi

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Eka Prasetyono

2015-09-01

Full Text Available Bidirectional DC-DC converter is needed in the energy storage system. The converter topology used in this paper was a non-isolated bidirectional DC-DC buck-boost converter. This converter worked in two ways, which the charging mode stored energy into battery when load current was less than nominal main DC current (set point and discharging mode transferred energy from battery to the load when its current exceeded set point value. Both of these modes worked automatically according to the load current. The charging and discharging currents were controlled by fuzzy logic controller which was implemented on microcontroller ARM Cortex-M4F STM32F407VG. This paper compares two types of fuzzy membership function (triangular and sigmoid in controlling bidirectional DC-DC converter. The results showed that fuzzy logic controller with triangle membership function and sigmoid as control bidirectional DC-DC converter had no significant different response, both had an average error for charging and discharging process under 4% with ripple current on the main DC bus around 0.5%. The computing time of program for fuzzy logic controller with triangular membership functions had 19.01% faster than sigmoid, and fuzzy logic computation time on a microcontroller with hardware floating point was 60% faster than software floating point.

Unmanned aerial system nadir reflectance and MODIS nadir BRDF-adjusted surface reflectances intercompared over Greenland

Directory of Open Access Journals (Sweden)

J. F. Burkhart

2017-07-01

Full Text Available Albedo is a fundamental parameter in earth sciences, and many analyses utilize the Moderate Resolution Imaging Spectroradiometer (MODIS bidirectional reflectance distribution function (BRDF/albedo (MCD43 algorithms. While derivative albedo products have been evaluated over Greenland, we present a novel, direct comparison with nadir surface reflectance collected from an unmanned aerial system (UAS. The UAS was flown from Summit, Greenland, on 210 km transects coincident with the MODIS sensor overpass on board the Aqua and Terra satellites on 5 and 6 August 2010. Clear-sky acquisitions were available from the overpasses within 2 h of the UAS flights. The UAS was equipped with upward- and downward-looking spectrometers (300–920 nm with a spectral resolution of 10 nm, allowing for direct integration into the MODIS bands 1, 3, and 4. The data provide a unique opportunity to directly compare UAS nadir reflectance with the MODIS nadir BRDF-adjusted surface reflectance (NBAR products. The data show UAS measurements are slightly higher than the MODIS NBARs for all bands but agree within their stated uncertainties. Differences in variability are observed as expected due to different footprints of the platforms. The UAS data demonstrate potentially large sub-pixel variability of MODIS reflectance products and the potential to explore this variability using the UAS as a platform. It is also found that, even at the low elevations flown typically by a UAS, reflectance measurements may be influenced by haze if present at and/or below the flight altitude of the UAS. This impact could explain some differences between data from the two platforms and should be considered in any use of airborne platforms.

Seismic reflection imaging, accounting for primary and multiple reflections

Science.gov (United States)

Wapenaar, Kees; van der Neut, Joost; Thorbecke, Jan; Broggini, Filippo; Slob, Evert; Snieder, Roel

2015-04-01

Imaging of seismic reflection data is usually based on the assumption that the seismic response consists of primary reflections only. Multiple reflections, i.e. waves that have reflected more than once, are treated as primaries and are imaged at wrong positions. There are two classes of multiple reflections, which we will call surface-related multiples and internal multiples. Surface-related multiples are those multiples that contain at least one reflection at the earth's surface, whereas internal multiples consist of waves that have reflected only at subsurface interfaces. Surface-related multiples are the strongest, but also relatively easy to deal with because the reflecting boundary (the earth's surface) is known. Internal multiples constitute a much more difficult problem for seismic imaging, because the positions and properties of the reflecting interfaces are not known. We are developing reflection imaging methodology which deals with internal multiples. Starting with the Marchenko equation for 1D inverse scattering problems, we derived 3D Marchenko-type equations, which relate reflection data at the surface to Green's functions between virtual sources anywhere in the subsurface and receivers at the surface. Based on these equations, we derived an iterative scheme by which these Green's functions can be retrieved from the reflection data at the surface. This iterative scheme requires an estimate of the direct wave of the Green's functions in a background medium. Note that this is precisely the same information that is also required by standard reflection imaging schemes. However, unlike in standard imaging, our iterative Marchenko scheme retrieves the multiple reflections of the Green's functions from the reflection data at the surface. For this, no knowledge of the positions and properties of the reflecting interfaces is required. Once the full Green's functions are retrieved, reflection imaging can be carried out by which the primaries and multiples are

A novel bidirectional expression system for simultaneous expression of both the protein-coding genes and short hairpin RNAs in mammalian cells

International Nuclear Information System (INIS)

Hung, C.-F.; Cheng, T.-L.; Wu, R.-H.; Teng, C.-F.; Chang, W.-T.

2006-01-01

RNA interference (RNAi) is an extremely powerful and widely used gene silencing approach for reverse functional genomics and molecular therapeutics. In mammals, the conserved poly(ADP-ribose) polymerase 2 (PARP-2)/RNase P bidirectional control promoter simultaneously expresses both the PARP-2 protein and RNase P RNA by RNA polymerase II- and III-dependent mechanisms, respectively. To explore this unique bidirectional control system in RNAi-mediated gene silencing strategy, we have constructed two novel bidirectional expression vectors, pbiHsH1 and pbiMmH1, which contained the PARP-2/RNase P bidirectional control promoters from human and mouse, for simultaneous expression of both the protein-coding genes and short hairpin RNAs. Analyses of the dual transcriptional activities indicated that these two bidirectional expression vectors could not only express enhanced green fluorescent protein as a functional reporter but also simultaneously transcribe shLuc for inhibiting the firefly luciferase expression. In addition, to extend its utility for the establishment of inherited stable clones, we have also reconstructed this bidirectional expression system with the blasticidin S deaminase gene, an effective dominant drug resistance selectable marker, and examined both the selection and inhibition efficiencies in drug resistance and gene expression. Moreover, we have further demonstrated that this bidirectional expression system could efficiently co-regulate the functionally important genes, such as overexpression of tumor suppressor protein p53 and inhibition of anti-apoptotic protein Bcl-2 at the same time. In summary, the bidirectional expression vectors, pbiHsH1 and pbiMmH1, should provide a simple, convenient, and efficient novel tool for manipulating the gene function in mammalian cells

Integrating high dimensional bi-directional parsing models for gene mention tagging.

Science.gov (United States)

Hsu, Chun-Nan; Chang, Yu-Ming; Kuo, Cheng-Ju; Lin, Yu-Shi; Huang, Han-Shen; Chung, I-Fang

2008-07-01

Tagging gene and gene product mentions in scientific text is an important initial step of literature mining. In this article, we describe in detail our gene mention tagger participated in BioCreative 2 challenge and analyze what contributes to its good performance. Our tagger is based on the conditional random fields model (CRF), the most prevailing method for the gene mention tagging task in BioCreative 2. Our tagger is interesting because it accomplished the highest F-scores among CRF-based methods and second over all. Moreover, we obtained our results by mostly applying open source packages, making it easy to duplicate our results. We first describe in detail how we developed our CRF-based tagger. We designed a very high dimensional feature set that includes most of information that may be relevant. We trained bi-directional CRF models with the same set of features, one applies forward parsing and the other backward, and integrated two models based on the output scores and dictionary filtering. One of the most prominent factors that contributes to the good performance of our tagger is the integration of an additional backward parsing model. However, from the definition of CRF, it appears that a CRF model is symmetric and bi-directional parsing models will produce the same results. We show that due to different feature settings, a CRF model can be asymmetric and the feature setting for our tagger in BioCreative 2 not only produces different results but also gives backward parsing models slight but constant advantage over forward parsing model. To fully explore the potential of integrating bi-directional parsing models, we applied different asymmetric feature settings to generate many bi-directional parsing models and integrate them based on the output scores. Experimental results show that this integrated model can achieve even higher F-score solely based on the training corpus for gene mention tagging. Data sets, programs and an on-line service of our gene

Control of parallel-connected bidirectional AC-DC converters in stationary frame for microgrid application

DEFF Research Database (Denmark)

Lu, Xiaonan; Guerrero, Josep M.; Teodorescu, Remus

2011-01-01

With the penetration of renewable energy in modern power system, microgrid has become a popular application worldwide. In this paper, parallel-connected bidirectional converters for AC and DC hybrid microgrid application are proposed as an efficient interface. To reach the goal of bidirectional...... power conversion, both rectifier and inverter modes are analyzed. In order to achieve high performance operation, hierarchical control system is accomplished. The control system is designed in stationary frame, with harmonic compensation in parallel and no coupled terms between axes. In this control...

Optical Estimation of the 3D Shape of a Solar Illuminated, Reflecting Satellite Surface

Science.gov (United States)

Antolin, J.; Yu, Z.; Prasad, S.

2016-09-01

The spatial distribution of the polarized component of the power reflected by a macroscopically smooth but microscopically roughened curved surface under highly directional illumination, as characterized by an appropriate bi-directional reflectance distribution function (BRDF), carries information about the three-dimensional (3D) shape of the surface. This information can be exploited to recover the surface shape locally under rather general conditions whenever power reflectance data for at least two different illumination or observation directions can be obtained. We present here two different parametric approaches for surface reconstruction, amounting to the recovery of the surface parameters that are either the global parameters of the family to which the surface is known a priori to belong or the coefficients of a low-order polynomial that can be employed to characterize a smoothly varying surface locally over the observed patch.

Measurement of Mechanical Properties of PVC Foam Using a Modified Arcan Fixture

DEFF Research Database (Denmark)

Taher, Siavash Talebi; Thomsen, Ole Thybo; M. Dulieu-Barton, Janice

, compressive and shear properties. The MAF enables the realization of unidirectional tensile, compressive and shear loading states, as well as high compression or tension to shear ratio bidirectional loading conditions. The MAF is attached to a standard universal test machine using specially designed grips......Previously, the Arcan test rig has been used to measure bidirectional properties of polymer foams used for sandwich core materials, especially in the tensile-shear stress region [1]. In this work, a modified Arcan fixture (MAF) is used to load polymer foam specimens to obtain their tensile...... that do not constrain the specimen either in-plane or out-of-plane and hence eliminate any paristic effects due to test machine misalignment. The focus of this paper is to compare and validate the accuracy of the material properties measured using the proposed MAF, by comparing with results obtained using...

Development of paints with infrared radiation reflective properties

Directory of Open Access Journals (Sweden)

Eliane Coser

2015-06-01

Full Text Available AbstractLarge buildings situated in hot regions of the Globe need to be agreeable to their residents. Air conditioning is extensively used to make these buildings comfortable, with consequent energy consumption. Absorption of solar visible and infrared radiations are responsible for heating objects on the surface of the Earth, including houses and buildings. To avoid excessive energy consumption, it is possible to use coatings formulated with special pigments that are able to reflect the radiation in the near- infrared, NIR, spectrum. To evaluate this phenomenon an experimental study about the reflectivity of paints containing infrared-reflective pigments has been made. By irradiating with an IR source and by measuring the surface temperatures of the samples we evaluated: color according to ASTM D 2244-14, UV/VIS/NIR reflectance according to ASTM E 903-12 and thermal performance. Additionally, the spectral reflectance and the IR emittance were measured and the solar reflectance of the samples were calculated. The results showed that plates coated with paints containing IR-reflecting pigments displayed lower air temperature on the opposite side as compared to conventional coatings, indicating that they can be effective to reflect NIR and decrease the temperature of buildings when used in roofs and walls.

Colours sometimes count : Awareness and bidirectionality in grapheme-colour synaesthesia

NARCIS (Netherlands)

Johnson, Addie; Jepma, Marieke; de Jong, Ritske

2007-01-01

Three experiments were conducted with 10 grapheme-colour synaesthetes and 10 matched controls to investigate (a) whether awareness of the inducer grapheme is necessary for synaesthetic colour induction and (b) whether grapheme-colour synaesthesia may be bidirectional in the sense that not only do

Bidirectional electrostatic linear shuffle motor with two degrees of freedom

NARCIS (Netherlands)

Sarajlic, Edin; Berenschot, Johan W.; Fujita, H.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

2005-01-01

We report on an electrostatic linear inchworm micromotor with two translational degrees-of-freedom. The motor employs built-in mechanical leverage to convert normal deflection of a flexible cross-plate into a small in-plane step and four electrostatic clamps to enable bidirectional inchworm motion

Magnetically actuated bi-directional microactuators with permalloy and Fe/Pt hard magnet

International Nuclear Information System (INIS)

Pan, C.T.; Shen, S.C.

2005-01-01

Bi-directional polyimide (PI) electromagnetic microactuator with different geometries are designed, fabricated and tested. Fabrication of the electromagnetic microactuator consists of 10 μm thick Ni/Fe (80/20) permalloy deposition on the PI diaphragm by electroplating, high aspect ratio electroplating of copper planar coil with 10 μm in thickness, bulk micromachining, and excimer laser selective ablation. They were fabricated by a novel concept avoiding the etching selectivity and residual stress problems during wafer etching. A mathematical model is created by ANSYS software to analyze the microactuator. The external magnetic field intensity (H ext ) generated by the planar coil is simulated by ANSYS software. ANSYS software is used to predict the deflection angle of the microactuator. Besides, to provide bi-directional and large deflection angle of microactuator, hard magnet Fe/Pt is deposited at a low temperature of 300 deg. C by sputtering onto the PI diaphragm to produce a perpendicular magnetic anisotropic field. This magnetic field can enhance the interaction with H ext to induce attractive and repulsive bi-directional force to provide large displacement. The results of magnetic microactuator with and without hard magnets are compared and discussed. The preliminary result reveals that the electromagnetic microactuator with hard magnet shows a greater deflection angle than that without one

Application of a neural network for reflectance spectrum classification

Science.gov (United States)

Yang, Gefei; Gartley, Michael

2017-05-01

Traditional reflectance spectrum classification algorithms are based on comparing spectrum across the electromagnetic spectrum anywhere from the ultra-violet to the thermal infrared regions. These methods analyze reflectance on a pixel by pixel basis. Inspired by high performance that Convolution Neural Networks (CNN) have demonstrated in image classification, we applied a neural network to analyze directional reflectance pattern images. By using the bidirectional reflectance distribution function (BRDF) data, we can reformulate the 4-dimensional into 2 dimensions, namely incident direction × reflected direction × channels. Meanwhile, RIT's micro-DIRSIG model is utilized to simulate additional training samples for improving the robustness of the neural networks training. Unlike traditional classification by using hand-designed feature extraction with a trainable classifier, neural networks create several layers to learn a feature hierarchy from pixels to classifier and all layers are trained jointly. Hence, the our approach of utilizing the angular features are different to traditional methods utilizing spatial features. Although training processing typically has a large computational cost, simple classifiers work well when subsequently using neural network generated features. Currently, most popular neural networks such as VGG, GoogLeNet and AlexNet are trained based on RGB spatial image data. Our approach aims to build a directional reflectance spectrum based neural network to help us to understand from another perspective. At the end of this paper, we compare the difference among several classifiers and analyze the trade-off among neural networks parameters.

Characterization, optical properties and laser ablation behavior of epoxy resin coatings reinforced with high reflectivity ceramic particles

Science.gov (United States)

Li, Wenzhi; Kong, Jing; Wu, Taotao; Gao, Lihong; Ma, Zhuang; Liu, Yanbo; Wang, Fuchi; Wei, Chenghua; Wang, Lijun

2018-04-01

Thermal damage induced by high power energy, especially high power laser, significantly affects the lifetime and performance of equipment. High-reflectance coating/film has attracted considerable attention due to its good performance in the damage protection. Preparing a high-reflectance coating with high reaction endothermal enthalpy will effectively consume a large amount of incident energy and in turn protect the substrate from thermal damage. In this study, a low temperature process was used to prepare coatings onto substrate with complex shape and avoid thermal effect during molding. An advanced high reflection ceramic powder, La1‑xSrxTiO3+δ , was added in the epoxy adhesive matrix to improve the reflectivity of coating. The optical properties and laser ablation behaviors of coatings with different ceramic additive ratio of La1‑xSrxTiO3+δ and modified epoxy-La1‑xSrxTiO3+δ with ammonium polyphosphate coatings were investigated, respectively. We found that the reflectivity of coatings is extremely high due to mixed high-reflection La1‑xSrxTiO3+δ particles, up to 96% at 1070 nm, which can significantly improve the laser resistance. In addition, the ammonium polyphosphate modifies the residual carbon structure of epoxy resin from discontinuous fine particles structure to continuous and porous structure, which greatly enhances the thermal-insulation property of coating. Furthermore, the laser ablation threshold is improved obviously, which is from 800 W cm‑2 to 1000 W cm‑2.

Interplanetary magnetic field orientations associated with bidirectional electron heat fluxes detected at ISEE 3

International Nuclear Information System (INIS)

Stansberry, J.A.; Gosling, J.T.; Thomsen, M.F.; Bame, S.J.; Smith, E.J.

1988-01-01

A statistical survey of interplanetary magnetic field orientations associated with bidirectional electron heat fluxes observed at ISEE 3 in orbit about the Sunward Lagrange point indicates that magnetic connection of the spacecraft to the Earth's bow shock was frequently the source of the bidirectionality. When the interplanetary magnetic field was oriented within 5 0 of the Earth-spacecraft line, backstreaming electrons from the bow shock were clearly observed approximately 18% of the time, and connections apparently occurred for angles as large as ∼30 0 --35 0 . copyright American Geophysical Union 1988

Multifunctional high-reflective and antireflective layer systems with easy-to-clean properties

International Nuclear Information System (INIS)

Gloess, D.; Frach, P.; Gottfried, C.; Klinkenberg, S.; Liebig, J.-S.; Hentsch, W.; Liepack, H.; Krug, M.

2008-01-01

High-reflective (HR) and even more antireflective (AR) layer systems are in use for widespread applications. Multifunctional layer systems providing high optical functionality with an easy-to-clean or a self-cleaning behaviour would be preferable for many applications to avoid soiling of the surface. In this paper, the feasibility of fabrication by highly productive pulse magnetron sputtering in an in-line coating plant is investigated. Easy-to-clean properties are achieved by a top layer of photocatalytic and photoinduced hydrophilic TiO 2 . Multifunctional HR layer systems were successfully deposited on glass and polyethylene terephthalate (PET) substrates at a low deposition temperature of 150 deg. C, demonstrating the possibility of coating certain polymer materials. Double-sided multifunctional AR layer systems with a single-sided photoinduced hydrophilic TiO 2 top coating have a resulting reflectivity of about 3% and transmittance of about 97% in the visible range of light

Bidirectional Relations between Authoritative Parenting and Adolescents' Prosocial Behaviors

Science.gov (United States)

Padilla-Walker, Laura M.; Carlo, Gustavo; Christensen, Katherine J.; Yorgason, Jeremy B.

2012-01-01

This study examined the bidirectional relations between authoritative parenting and adolescents' prosocial behavior over a 1-year time period. Data were taken from Time 2 and 3 of the Flourishing Families Project, and included reports from 319 two-parent families with an adolescent child (M age of child at Time 2 = 12.34, SD = 1.06, 52% girls).…

Bidirectional Tachycardia after an Acute Intravenous Administration of Digitalis for a Suicidal Gesture

Directory of Open Access Journals (Sweden)

Diletta Sabatini

2014-01-01

Full Text Available Acute digoxin intoxication is a life-threating condition associated with severe cardiotoxicity. Female gender, age, low lean body mass, hypertension, and renal insufficiency may worsen the prognosis. Arrhythmias caused by digitalis glycosides are characterized by an increased automaticity coupled with concomitant conduction delay. Bidirectional tachycardia is pathognomonic of digoxin intoxication, but it is rarely observed. An 83-year-old woman was admitted to the Emergency Department after self-administration of 5 mg of digoxin i.v. for suicidal purpose. Her digoxin serum concentration was 17.4 ng/mL. The patient developed a bidirectional tachycardia and the Poison Control Center of the hospital provided digoxin immune fab. Bidirectional tachycardia quickly reversed and the patient remained stable throughout the hospital stay. This case shows that a multiple disciplinary approach, involving cardiologists and toxicologists, is essential for the management of digoxin intoxication. The optimal treatment of this rare event depends on the clinical conditions and on the serum drug concentration of the patient. Digoxin immune fab represents a safe, effective, and specific method for rapidly reversing digitalis cardiotoxicity and should be started as soon as the diagnosis is defined.

Bidirectional Associations between Peer Relations and Attention Problems from 9 to 16 Years.

Science.gov (United States)

Ji, Linqin; Pan, Bin; Zhang, Wenxin; Zhang, Liang; Chen, Liang; Deater-Deckard, Kirby

2018-05-12

We examined the bidirectional relations between peer relations and attention problems from middle childhood through adolescence. Using data from the Longitudinal Study of Chinese Children and Adolescents (LSCCA, N = 2157, 51.9% male), three key aspects of peer relations (acceptance, rejection, and victimization) were assessed annually from 9 to 16 years of age. Attention problems were assessed at 9 and 15 years. Latent growth modeling indicated that greater attention problems at age 9 were linked with a lower intercept for peer acceptance, and higher intercepts for rejection and victimization. Also, prior lower acceptance and greater rejection and victimization, along with a higher increase over time in rejection and lower decrease over time in victimization, predicted attention problems at age 15. Cross-lagged analysis showed that attention problems were associated with less subsequent peer acceptance and greater subsequent rejection and victimization. Only peer rejection (but neither victimization nor acceptance) predicted more subsequent attention problems. Findings point to bidirectional associations between attention problems and peer relations in the developmental transition across adolescence. Evidence for differential bidirectionality of attention problems with the multiple peer experience (group versus dyadic; good versus bad) emerged, and future replications are needed.

Evaluation of a bi-directional aluminum honeycomb impact limiter design

International Nuclear Information System (INIS)

Doman, M.J.

1995-01-01

A 120 Ton shipping cask is being developed for the on-site shipment of dry spent fuel at the Idaho National Engineering Laboratory. Impact limiters were incorporated in the cask design to limit the inertial load of the package and its contents during the hypothetical 9-meter (30-foot) drop accident required by 10CFR71. The design process included: (1) a series of static and dynamic tests to determine the crush characteristics of the bi-directional aluminum honeycomb impact limiter material, (2) the development of an analytical model to predict the cask deceleration force as a function of impact limiter crush, and (3) a series of quarter scale model drop tests to qualify the analytical model. The scale model testing, performed at Sandia National Laboratory in Albuquerque, New Mexico, revealed several design aspects which should be considered in developing bi-directional aluminum honeycomb impact limiters and several other design aspects which should be considered for impact limiter designs in general

Bidirectional composition on lie groups for gradient-based image alignment.

Science.gov (United States)

Mégret, Rémi; Authesserre, Jean-Baptiste; Berthoumieu, Yannick

2010-09-01

In this paper, a new formulation based on bidirectional composition on Lie groups (BCL) for parametric gradient-based image alignment is presented. Contrary to the conventional approaches, the BCL method takes advantage of the gradients of both template and current image without combining them a priori. Based on this bidirectional formulation, two methods are proposed and their relationship with state-of-the-art gradient based approaches is fully discussed. The first one, i.e., the BCL method, relies on the compositional framework to provide the minimization of the compensated error with respect to an augmented parameter vector. The second one, the projected BCL (PBCL), corresponds to a close approximation of the BCL approach. A comparative study is carried out dealing with computational complexity, convergence rate and frequence of convergence. Numerical experiments using a conventional benchmark show the performance improvement especially for asymmetric levels of noise, which is also discussed from a theoretical point of view.

Non-linear seismic response of base-isolated liquid storage tanks to bi-directional excitation

International Nuclear Information System (INIS)

Shrimali, M.K.; Jangid, R.S.

2002-01-01

Seismic response of the liquid storage tanks isolated by lead-rubber bearings is investigated for bi-directional earthquake excitation (i.e. two horizontal components). The biaxial force-deformation behaviour of the bearings is considered as bi-linear modelled by coupled non-linear differential equations. The continuous liquid mass of the tank is modelled as lumped masses known as convective mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses has been worked out depending upon the properties of the tank wall and liquid mass. Since the force-deformation behaviour of the bearings is non-linear, as a result, the seismic response is obtained by the Newmark's step-by-step method. The seismic responses of two types of the isolated tanks (i.e. slender and broad) are investigated under several recorded earthquake ground to study the effects of bi-directional interaction. Further, a parametric study is also carried out to study the effects of important system parameters on the effectiveness of seismic isolation for liquid storage tanks. The various important parameters considered are: (i) the period of isolation, (ii) the damping of isolation bearings and (iii) the yield strength level of the bearings. It has been observed that the seismic response of isolated tank is found to be insensitive to interaction effect of the bearing forces. Further, there exists an optimum value of isolation damping for which the base shear in the tank attains the minimum value. Therefore, increasing the bearing damping beyond a certain value may decrease the bearing and sloshing displacements but it may increase the base shear

Bidirectional Retroviral Integration Site PCR Methodology and Quantitative Data Analysis Workflow.

Science.gov (United States)

Suryawanshi, Gajendra W; Xu, Song; Xie, Yiming; Chou, Tom; Kim, Namshin; Chen, Irvin S Y; Kim, Sanggu

2017-06-14

Integration Site (IS) assays are a critical component of the study of retroviral integration sites and their biological significance. In recent retroviral gene therapy studies, IS assays, in combination with next-generation sequencing, have been used as a cell-tracking tool to characterize clonal stem cell populations sharing the same IS. For the accurate comparison of repopulating stem cell clones within and across different samples, the detection sensitivity, data reproducibility, and high-throughput capacity of the assay are among the most important assay qualities. This work provides a detailed protocol and data analysis workflow for bidirectional IS analysis. The bidirectional assay can simultaneously sequence both upstream and downstream vector-host junctions. Compared to conventional unidirectional IS sequencing approaches, the bidirectional approach significantly improves IS detection rates and the characterization of integration events at both ends of the target DNA. The data analysis pipeline described here accurately identifies and enumerates identical IS sequences through multiple steps of comparison that map IS sequences onto the reference genome and determine sequencing errors. Using an optimized assay procedure, we have recently published the detailed repopulation patterns of thousands of Hematopoietic Stem Cell (HSC) clones following transplant in rhesus macaques, demonstrating for the first time the precise time point of HSC repopulation and the functional heterogeneity of HSCs in the primate system. The following protocol describes the step-by-step experimental procedure and data analysis workflow that accurately identifies and quantifies identical IS sequences.

Light-scattering properties of a Venetian blind slat used for daylighting applications

Energy Technology Data Exchange (ETDEWEB)

Nilsson, Annica M. [Department of Engineering Sciences, Angstroem Laboratory, Uppsala University (Sweden); Jonsson, Jacob C. [Environmental Energy Technology Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

2010-12-15

The low cost, simplicity, and aesthetic appearance of external and internal shading devices, make them commonly used for daylighting and glare-control applications. Shading devices, such as Venetian blinds, screens, and roller shades, generally exhibit light scattering and/or light redirecting properties. This requires the bi-directional scattering distribution function (BSDF) of the material to be known in order to accurately predict the daylight distribution and energy flow through the fenestration system. Acquiring the complete BSDF is not a straightforward task, and to complete the process it is often required that a model is used to complement the measured data. In this project, a Venetian blind slat with a white top surface and a brushed aluminum bottom surface was optically characterized. A goniophotometer and an integrating sphere spectrophotometer were used to determine the angle resolved and hemispherical reflectance of the sample, respectively. The acquired data were fitted to a scattering model providing one Lambertian and one angle dependent description of the surface properties. These were used in combination with raytracing to obtain the complete BSDFs of the Venetian blind system. (author)

Bidirectional Microglia-Neuron Communication in the Healthy Brain

Directory of Open Access Journals (Sweden)

Ukpong B. Eyo

2013-01-01

Full Text Available Unlike other resident neural cells that are of neuroectodermal origin, microglia are resident neural cells of mesodermal origin. Traditionally recognized for their immune functions during disease, new roles are being attributed to these cells in the development and maintenance of the central nervous system (CNS including specific communication with neurons. In this review, we highlight some of the recent findings on the bidirectional interaction between neurons and microglia. We discuss these interactions along two lines. First, we review data that suggest that microglial activity is modulated by neuronal signals, focusing on evidence that (i neurons are capable of regulating microglial activation state and influence basal microglial activities; (ii classic neurotransmitters affect microglial behavior; (iii chemotactic signals attract microglia during acute neuronal injury. Next, we discuss some of the recent data on how microglia signal to neurons. Signaling mechanisms include (i direct physical contact of microglial processes with neuronal elements; (ii microglial regulation of neuronal synapse and circuit by fractalkine, complement, and DAP12 signaling. In addition, we discuss the use of microglial depletion strategies in studying the role of microglia in neuronal development and synaptic physiology. Deciphering the mechanisms of bidirectional microglial-neuronal communication provides novel insights in understanding microglial function in both the healthy and diseased brain.

Performance analysis and comparison of a minimum interconnections direct storage model with traditional neural bidirectional memories.

Science.gov (United States)

Bhatti, A Aziz

2009-12-01

This study proposes an efficient and improved model of a direct storage bidirectional memory, improved bidirectional associative memory (IBAM), and emphasises the use of nanotechnology for efficient implementation of such large-scale neural network structures at a considerable lower cost reduced complexity, and less area required for implementation. This memory model directly stores the X and Y associated sets of M bipolar binary vectors in the form of (MxN(x)) and (MxN(y)) memory matrices, requires O(N) or about 30% of interconnections with weight strength ranging between +/-1, and is computationally very efficient as compared to sequential, intraconnected and other bidirectional associative memory (BAM) models of outer-product type that require O(N(2)) complex interconnections with weight strength ranging between +/-M. It is shown that it is functionally equivalent to and possesses all attributes of a BAM of outer-product type, and yet it is simple and robust in structure, very large scale integration (VLSI), optical and nanotechnology realisable, modular and expandable neural network bidirectional associative memory model in which the addition or deletion of a pair of vectors does not require changes in the strength of interconnections of the entire memory matrix. The analysis of retrieval process, signal-to-noise ratio, storage capacity and stability of the proposed model as well as of the traditional BAM has been carried out. Constraints on and characteristics of unipolar and bipolar binaries for improved storage and retrieval are discussed. The simulation results show that it has log(e) N times higher storage capacity, superior performance, faster convergence and retrieval time, when compared to traditional sequential and intraconnected bidirectional memories.

Restoring natural sensory feedback in real-time bidirectional hand prostheses

DEFF Research Database (Denmark)

Raspopovic, Stanisa; Capogrosso, Marco; Petrini, Francesco Maria

2014-01-01

Hand loss is a highly disabling event that markedly affects the quality of life. To achieve a close to natural replacement for the lost hand, the user should be provided with the rich sensations that we naturally perceive when grasping or manipulating an object. Ideal bidirectional hand prosthese...

Bidirectional converter interface for a battery energy storage test bench

DEFF Research Database (Denmark)

Trintis, Ionut; Thomas, Stephan; Blank, Tobias

2011-01-01

This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...

High-power three-port three-phase bidirectional DC-DC converter

NARCIS (Netherlands)

Tao, H.; Duarte, J.L.; Hendrix, M.A.M.

2007-01-01

This paper proposes a three-port three-phase bidirectional dc-dc converter suitable for high-power applications. The converter combines a slow primary source and a fast storage to power a common load (e.g., an inverter). Since this type of system is gaining popularity in sustainable energy

A Study of Bi-Directional Reflectance Distribution Functions and Their Effect on Infrared Signature Models

Science.gov (United States)

2007-03-01

66 3.5.1 Specular Reflection Assumption . . . . . . . . . . . . . . . . . . . 70 3.5.2 Radiosity ...69 3.31. Radiosity Algorithm Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 3.32. POV...3.5.2 Radiosity . The first algorithm implemented to attempt to hemispher- ically integrate the irradiance contribution was classical radiosity as

Impact of Interference in Coexisting Wireless Networks with Applications to Arbitrarily Varying Bidirectional Broadcast Channels

Directory of Open Access Journals (Sweden)

Holger Boche

2012-08-01

Full Text Available The paradigm shift from an exclusive allocation of frequency bands, one for each system, to a shared use of frequencies comes along with the need of new concepts since interference will be an ubiquitous phenomenon. In this paper, we use the concept of arbitrarily varying channels to model the impact of unknown interference caused by coexisting wireless systems which operate on the same frequencies. Within this framework, capacity can be zero if pre-specified encoders and decoders are used. This necessitates the use of more sophisticated coordination schemes where the choice of encoders and decoders is additionally coordinated based on common randomness. As an application we study the arbitrarily varying bidirectional broadcast channel and derive the capacity regions for different coordination strategies. This problem is motivated by decode-and-forward bidirectional or two-way relaying, where a relay establishes a bidirectional communication between two other nodes while sharing the resources with other coexisting wireless networks.

Evaluation of retro-reflective coating performance by reflectance and perceived relative brightness measurements

International Nuclear Information System (INIS)

Luse, Kaiva; Pausus, Anete; Karitans, Varis; Ozolins, Maris; Tukisa, Madara

2011-01-01

Retro-reflective properties of six types and five different colors or retro-reflective materials were discussed in this paper. Reflectance optical indicatrix of samples was determined and compared to obtained psychophyisical data of perceived brightness of human observer. Microscopic structure of the retro-reflective active regions of RR's was studied. Statistically significant differences in reflectivity and brightness of various types and colors of RR's were found.

Bidirectional relations between work-related stress, sleep quality and perseverative cognition

NARCIS (Netherlands)

Laethem, M. van; Beckers, D.G.J.; Kompier, M.A.J.; Kecklund, L.G.; Bossche, S.N.J. van den; Geurts, S.A.E.

2015-01-01

Objective In this longitudinal two-wave study, bidirectional relations between work-related stress and sleep quality were examined. Moreover, it was investigated whether perseverative cognition is a potential underlying mechanism in this association, related to both work-related stress and sleep

Optimized Free Energies from Bidirectional Single-Molecule Force Spectroscopy

Science.gov (United States)

Minh, David D. L.; Adib, Artur B.

2008-05-01

An optimized method for estimating path-ensemble averages using data from processes driven in opposite directions is presented. Based on this estimator, bidirectional expressions for reconstructing free energies and potentials of mean force from single-molecule force spectroscopy—valid for biasing potentials of arbitrary stiffness—are developed. Numerical simulations on a model potential indicate that these methods perform better than unidirectional strategies.

It's a two-way street: the bidirectional relationship between parenting and delinquency.

Science.gov (United States)

Gault-Sherman, Martha

2012-02-01

As the primary socializing institution of youth, the family has long been recognized as important for predicting delinquency. Social control theory focuses on the effects of parental behavior on adolescent delinquency but fails to take into account the effect of adolescent delinquency on parental behaviors. This study addresses this problem by estimating eighteen models examining bidirectional relationships between general, property, and violent delinquency and parental attachment, monitoring, and involvement. The magnitude of both parent and child effects were examined using data from 12,505 youth ages twelve to seventeen who participated in the Add Health study. These youth were an average age of 14 and were predominantly white (65%); just over half (50.42%) were female. Cross-lag regressions showed that while parental attachment has an effect on delinquency, an adolescent's delinquency also impacts parental attachment, regardless of the type of delinquency. Findings also revealed no significant parental effects of monitoring or involvement on any type of delinquency, and the only child effects revealed for monitoring or involvement were for involvement, which decreases when overall or property delinquency increases. The findings regarding parental attachment provide strong evidence for the existence of a reciprocal relationship between parenting and delinquency, consistent with the transactional and interactional models of reciprocal parent-child relationships.

Bidirectional Associations among Sensitive Parenting, Language Development, and Social Competence

Science.gov (United States)

Barnett, Melissa A.; Gustafsson, Hanna; Deng, Min; Mills-Koonce, W. Roger; Cox, Martha

2012-01-01

Rapid changes in language skills and social competence, both of which are linked to sensitive parenting, characterize early childhood. The present study examines bidirectional associations among mothers' sensitive parenting and children's language skills and social competence from 24 to 36?months in a community sample of 174 families. In addition,…

"Figuring" Bidirectional Home and School Connections along the Biliteracy Continuum

Science.gov (United States)

Fránquiz, María E.; Leija, María G.; Garza, Irene

2015-01-01

This article centers on the significant practices identified by bilingual teachers who participated in Proyecto Bilingüe, a specialized master's degree program. The notion of bidirectional theory of bilingual pedagogy and the theoretical construct of the continua of biliteracy are utilized to illustrate how the teachers centered home and school…

TOOL ASSEMBLY WITH BI-DIRECTIONAL BEARING

Science.gov (United States)

Longhurst, G.E.

1961-07-11

A two-direction motion bearing which is incorporated in a refueling nuclear fuel element trsnsfer tool assembly is described. A plurality of bi- directional bearing assembliesare fixed equi-distantly about the circumference of the transfer tool assembly to provide the tool assembly with a bearing surface- for both axial and rotational motion. Each bi-directional bearing assembly contains a plurality of circumferentially bulged rollers mounted in a unique arrangement which will provide a bearing surface for rotational movement of the tool assembly within a bore. The bi-direc tional bearing assembly itself is capable of rational motion and thus provides for longitudinal movement of the tool assembly.

Fast and exact Newton and Bidirectional fitting of Active Appearance Models.

Science.gov (United States)

Kossaifi, Jean; Tzimiropoulos, Yorgos; Pantic, Maja

2016-12-21

Active Appearance Models (AAMs) are generative models of shape and appearance that have proven very attractive for their ability to handle wide changes in illumination, pose and occlusion when trained in the wild, while not requiring large training dataset like regression-based or deep learning methods. The problem of fitting an AAM is usually formulated as a non-linear least squares one and the main way of solving it is a standard Gauss-Newton algorithm. In this paper we extend Active Appearance Models in two ways: we first extend the Gauss-Newton framework by formulating a bidirectional fitting method that deforms both the image and the template to fit a new instance. We then formulate a second order method by deriving an efficient Newton method for AAMs fitting. We derive both methods in a unified framework for two types of Active Appearance Models, holistic and part-based, and additionally show how to exploit the structure in the problem to derive fast yet exact solutions. We perform a thorough evaluation of all algorithms on three challenging and recently annotated inthe- wild datasets, and investigate fitting accuracy, convergence properties and the influence of noise in the initialisation. We compare our proposed methods to other algorithms and show that they yield state-of-the-art results, out-performing other methods while having superior convergence properties.

Development of a High Resolution BRDF/Albedo Product by Fusing Airborne CASI Reflectance with MODIS Daily Reflectance in the Oasis Area of the Heihe River Basin, China

Directory of Open Access Journals (Sweden)

Dongqin You

2015-05-01

Full Text Available A land-cover-based linear BRDF (bi-directional reflectance distribution function unmixing (LLBU algorithm based on the kernel-driven model is proposed to combine the compact airborne spectrographic imager (CASI reflectance with the moderate resolution imaging spectroradiometer (MODIS daily reflectance product to derive the BRDF/albedo of the two sensors simultaneously in the foci experimental area (FEA of the Heihe Watershed Allied Telemetry Experimental Research (HiWATER, which was carried out in the Heihe River basin, China. For each land cover type, an archetypal BRDF, which characterizes the shape of its anisotropic reflectance, is extracted by linearly unmixing from the MODIS reflectance with the assistance of a high-resolution classification map. The isotropic coefficients accounting for the differences within a class are derived from the CASI reflectance. The BRDF is finally determined by the archetypal BRDF and the corresponding isotropic coefficients. Direct comparisons of the cropland archetypal BRDF and CASI albedo with in situ measurements show good agreement. An indirect validation which compares retrieved BRDF/albedo with that of the MCD43A1 standard product issued by NASA and aggregated CASI albedo also suggests reasonable reliability. LLBU has potential to retrieve the high spatial resolution BRDF/albedo product for airborne and spaceborne sensors which have inadequate angular samplings. In addition, it can shorten the timescale for coarse spatial resolution product like MODIS.

Evaluation of retro-reflective coating performance by reflectance and perceived relative brightness measurements

Energy Technology Data Exchange (ETDEWEB)

Luse, Kaiva; Pausus, Anete; Karitans, Varis; Ozolins, Maris; Tukisa, Madara, E-mail: kaiva.luse@gmail.com [University of Latvia, Optometry and Vision Science Department, Kengaraga street 8, Riga LV-1063 (Latvia)

2011-06-23

Retro-reflective properties of six types and five different colors or retro-reflective materials were discussed in this paper. Reflectance optical indicatrix of samples was determined and compared to obtained psychophyisical data of perceived brightness of human observer. Microscopic structure of the retro-reflective active regions of RR's was studied. Statistically significant differences in reflectivity and brightness of various types and colors of RR's were found.

Statistical inference for classification of RRIM clone series using near IR reflectance properties

Science.gov (United States)

Ismail, Faridatul Aima; Madzhi, Nina Korlina; Hashim, Hadzli; Abdullah, Noor Ezan; Khairuzzaman, Noor Aishah; Azmi, Azrie Faris Mohd; Sampian, Ahmad Faiz Mohd; Harun, Muhammad Hafiz

2015-08-01

RRIM clone is a rubber breeding series produced by RRIM (Rubber Research Institute of Malaysia) through "rubber breeding program" to improve latex yield and producing clones attractive to farmers. The objective of this work is to analyse measurement of optical sensing device on latex of selected clone series. The device using transmitting NIR properties and its reflectance is converted in terms of voltage. The obtained reflectance index value via voltage was analyzed using statistical technique in order to find out the discrimination among the clones. From the statistical results using error plots and one-way ANOVA test, there is an overwhelming evidence showing discrimination of RRIM 2002, RRIM 2007 and RRIM 3001 clone series with p value = 0.000. RRIM 2008 cannot be discriminated with RRIM 2014; however both of these groups are distinct from the other clones.

Investigations of bi-directional flow behaviour of a large vertical opening in containment

International Nuclear Information System (INIS)

Sharma, Pavan K.; Markandeya, S.G.; Ghosh, A.K.; Kushwaha, H.S.

2002-01-01

Full text: In the complex codes developed for fire analysis and for containment thermal hydraulic analysis. The junction in the multi-compartment geometries are often modeled as uni-directional junctions. However, certain large size junctions are known to depict bi-directional flow behaviour under specific circumstances. Detailed investigations have been carried out to understand the bi-directionality of a junction by analyzing an earlier reported case study of fire in an enclosure. A computer code FDS was used for the analysis. The paper presents the details of the analysis, the results obtained and further studies required to be conducted so that the findings can be applied to the fire/containment thermal hydraulics analysis codes successfully

Reconstruction of MODIS Spectral Reflectance under Cloudy-Sky Condition

Directory of Open Access Journals (Sweden)

Bo Gao

2016-09-01

Full Text Available Clouds usually cause invalid observations for sensors aboard satellites, which corrupts the spatio-temporal continuity of land surface parameters retrieved from remote sensing data (e.g., MODerate Resolution Imaging Spectroradiometer (MODIS data and prevents the fusing of multi-source remote sensing data in the field of quantitative remote sensing. Based on the requirements of spatio-temporal continuity and the necessity of methods to restore bad pixels, primarily resulting from image processing, this study developed a novel method to derive the spectral reflectance for MODIS band of cloudy pixels in the visual–near infrared (VIS–NIR spectral channel based on the Bidirectional Reflectance Distribution Function (BRDF and multi-spatio-temporal observations. The proposed method first constructs the spatial distribution of land surface reflectance based on the corresponding BRDF and the solar-viewing geometry; then, a geographically weighted regression (GWR is introduced to individually derive the spectral surface reflectance for MODIS band of cloudy pixels. A validation of the proposed method shows that a total root-mean-square error (RMSE of less than 6% and a total R2 of more than 90% are detected, which indicates considerably better precision than those exhibited by other existing methods. Further validation of the retrieved white-sky albedo based on the spectral reflectance for MODIS band of cloudy pixels confirms an RMSE of 3.6% and a bias of 2.2%, demonstrating very high accuracy of the proposed method.

Superior vena cava syndrome after pulsatile bidirectional Glenn shunt procedure: Perioperative implications

Directory of Open Access Journals (Sweden)

Neema Praveen

2009-01-01

Full Text Available Bidirectional superior cavopulmonary shunt (bidirectional Glenn shunt is generally performed in many congenital cardiac anomalies where complete two ventricle circulations cannot be easily achieved. The advantages of BDG shunt are achieved by partially separating the pulmonary and systemic venous circuits, and include reduced ventricular preload and long-term preservation of myocardium. The benefits of additional pulsatile pulmonary blood flow include the potential growth of pulmonary arteries, possible improvement in arterial oxygen saturation, and possible prevention of development of pulmonary arteriovenous malformations. However, increase in the systemic venous pressure after BDG with additional pulsatile blood flow is known. We describe the peri-operative implications of severe flow reversal in the superior vena cava after pulsatile BDG shunt construction in a child who presented for surgical interruption of the main pulmonary artery.

Coherent Detection for 1550 nm, 5 Gbit/s VCSEL Based 40 km Bidirectional PON Transmission

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee; Rodes Lopez, Roberto; Zibar, Darko

2011-01-01

Coherent detection of directly modulated 1550nm VCSELs in 5Gbit/s bidirectional 40km SSMF PON-links is presented. Receiver sensitivity of –37.3dBm after transmission is achieved with 30dB system margin, corresponding to 1:1024 passive powersplitting.......Coherent detection of directly modulated 1550nm VCSELs in 5Gbit/s bidirectional 40km SSMF PON-links is presented. Receiver sensitivity of –37.3dBm after transmission is achieved with 30dB system margin, corresponding to 1:1024 passive powersplitting....

Assessment of MODIS BRDF/Albedo Model Parameters (MCD43A1 Collection 6) for directional reflectance retrieval

Science.gov (United States)

Che, X.; Feng, M.; Sexton, J. O.; Channan, S.; Yang, Y.; Song, J.

2017-12-01

Reflection of solar radiation from Earth's surface is the basis for retrieving many higher-level terrestrial attributes such as vegetation indices and albedo. However, reflectance varies with the illumination and viewing geometry of observation (Bi-directional Reflectance Distribution Function (BRDF)) even with constant surface properties, and correcting for these artifacts increases precision of comparisons of images and time series acquired from satellites with different illumination and observation geometries. The operational MODIS processing inverts MODIS BRDF/Albedo Model Parameters (MCD43A1) to retrieve directional reflectance at any solar and view angles, and recently the MCD43A1 (Collection 6) was updated and distributed. We quantified the ability of MCD43A1 Collection 6 for retrieving directional reflectance compared to Collection 5 and tested whether changes in the land surface change over a 16-day composite period affect time series of directional reflectance. Correcting the Terra MODIS daily Surface Reflectance (MOD09GA) to the illumination and view geometries of coincidental Aqua MODIS daily Surface Reflectance (MYD09GA), MCD43A4 Collection 6 and Landsat-5 TM imagery show that the BRDF-corrected results using MCD43A1 Collection 6 hold a higher consistency with higher R2 (0.63 0.955), the slopes close to unity (0.718 0.955) and the lower RMSD (0.422 3.142) and MAE (0.282 1.735) reduced by about 10% than Collection 5. A simple parameter calibration to evaluate the variability of the roughness (R) and the volumetric (V) BRDF parameters for MCD43A1 Collection 6 shows that the assumption of stable land surface characteristic over 16-days composite period, used for BRDF parameters inversion, is plausible in spite of small improvement of directional reflectance and BRDF parameters time series. The larger fluctuations for the MCD43A1 Collection 6 do not have a discernable impact on the reflectance time series. All of these results shows that MCD43A1 Collection

Bi-directional relationship between pregnancy and periodontal disease.

Science.gov (United States)

Armitage, Gary C

2013-02-01

During pregnancy profound perturbations in innate and adaptive immunity impact the clinical course of a number of infectious diseases, including those affecting periodontal tissues. Conversely, it has been suggested that periodontal infections may increase the risk of adverse pregnancy outcomes. In this review, a summary of the literature associated with the bidirectional relationship between pregnancy and periodontal disease as well as the possible mechanisms behind this interaction were examined. © 2013 John Wiley & Sons A/S.

Dynamical implications of bi-directional resource exchange within a meta-ecosystem.

Science.gov (United States)

Rodriguez, Marisabel Rodriguez; Kopp, Darin; Allen, Daniel; Kang, Yun

2018-05-05

The exchange of resources across ecosystem boundaries can have large impacts on ecosystem structures and functions at local and regional scales. In this article, we develop a simple model to investigate dynamical implications of bi-directional resource exchanges between two local ecosystems in a meta-ecosystem framework. In our model, we assume that (1) Each local ecosystem acts as both a resource donor and recipient, such that one ecosystem donating resources to another results in a cost to the donating system and a benefit to the recipient; and (2) The costs and benefits of the bi-directional resource exchange between two ecosystems are correlated in a nonlinear fashion. Our model could apply to the resource interactions between terrestrial and aquatic ecosystems that are supported by the literature. Our theoretical results show that bi-directional resource exchange between two ecosystems can indeed generate complicated dynamical outcomes, including the coupled ecosystems having amensalistic, antagonistic, competitive, or mutualistic interactions, with multiple alternative stable states depending on the relative costs and benefits. In addition, if the relative cost for resource exchange for an ecosystem is decreased or the relative benefit for resource exchange for an ecosystem is increased, the production of that ecosystem would increase; however, depending on the local environment, the production of the other ecosystem may increase or decrease. We expect that our work, by evaluating the potential outcomes of resource exchange theoretically, can facilitate empirical evaluations and advance the understanding of spatial ecosystem ecology where resource exchanges occur in varied ecosystems through a complicated network. Copyright © 2018. Published by Elsevier Inc.

The normalization of surface anisotropy effects present in SEVIRI reflectances by using the MODIS BRDF method

DEFF Research Database (Denmark)

Proud, Simon Richard; Zhang, Qingling; Schaaf, Crystal

2014-01-01

A modified version of the MODerate resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) algorithm is presented for use in the angular normalization of surface reflectance data gathered by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI...... acquisition period than the comparable MODIS products while, at the same time, removing many of the angular perturbations present within the original MSG data. The NBAR data are validated against reflectance data from the MODIS instrument and in situ data gathered at a field location in Africa throughout 2008....... It is found that the MSG retrievals are stable and are of high-quality across much of the SEVIRI disk while maintaining a higher temporal resolution than the MODIS BRDF products. However, a number of circumstances are discovered whereby the BRDF model is unable to function correctly with the SEVIRI...

An Improved Multidimensional MPA Procedure for Bidirectional Earthquake Excitations

OpenAIRE

Wang, Feng; Sun, Jian-Gang; Zhang, Ning

2014-01-01

Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA) method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two compone...

Bidirectional dynamics of materialism and loneliness : Not just a vicious cycle

NARCIS (Netherlands)

Pieters, R.

2013-01-01

This research is the first to test the hypothesis that consumers face a “material trap” in which materialism fosters social isolation which in turn reinforces materialism. It provides evidence that materialism and loneliness are engaged in bidirectional relationships over time. Importantly, it finds

A bidirectional brain-machine interface featuring a neuromorphic hardware decoder

Directory of Open Access Journals (Sweden)

Fabio Boi

2016-12-01

Full Text Available Bidirectional brain-machine interfaces (BMIs establish a two-way direct communication link4 between the brain and the external world. A decoder translates recorded neural activity into motor5 commands and an encoder delivers sensory information collected from the environment directly6 to the brain creating a closed-loop system. These two modules are typically integrated in bulky7 external devices. However, the clinical support of patients with severe motor and sensory deficits8 requires compact, low-power, and fully implantable systems that can decode neural signals to9 control external devices. As a first step toward this goal, we developed a modular bidirectional BMI10 setup that uses a compact neuromorphic processor as a decoder. On this chip we implemented11 a network of spiking neurons built using its ultra-low-power mixed-signal analog/digital circuits.12 On-chip on-line spike-timing-dependent plasticity synapse circuits enabled the network to learn13 to decode neural signals recorded from the brain into motor outputs controlling the movements14 of an external device. The modularity of the BMI allowed us to tune the individual components15 of the setup without modifying the whole system. In this paper we present the features of16 this modular BMI, and describe how we configured the network of spiking neuron circuits to17 implement the decoder and to coordinate it with the encoder in an experimental BMI paradigm18 that connects bidirectionally the brain of an anesthetized rat with an external object. We show that19 the chip learned the decoding task correctly, allowing the interfaced brain to control the object’s20 trajectories robustly. Based on our demonstration, we propose that neuromorphic technology is21 mature enough for the development of BMI modules that are sufficiently low-power and compact,22 while being highly computationally powerful and adaptive.

A Bidirectional Brain-Machine Interface Featuring a Neuromorphic Hardware Decoder.

Science.gov (United States)

Boi, Fabio; Moraitis, Timoleon; De Feo, Vito; Diotalevi, Francesco; Bartolozzi, Chiara; Indiveri, Giacomo; Vato, Alessandro

2016-01-01

Bidirectional brain-machine interfaces (BMIs) establish a two-way direct communication link between the brain and the external world. A decoder translates recorded neural activity into motor commands and an encoder delivers sensory information collected from the environment directly to the brain creating a closed-loop system. These two modules are typically integrated in bulky external devices. However, the clinical support of patients with severe motor and sensory deficits requires compact, low-power, and fully implantable systems that can decode neural signals to control external devices. As a first step toward this goal, we developed a modular bidirectional BMI setup that uses a compact neuromorphic processor as a decoder. On this chip we implemented a network of spiking neurons built using its ultra-low-power mixed-signal analog/digital circuits. On-chip on-line spike-timing-dependent plasticity synapse circuits enabled the network to learn to decode neural signals recorded from the brain into motor outputs controlling the movements of an external device. The modularity of the BMI allowed us to tune the individual components of the setup without modifying the whole system. In this paper, we present the features of this modular BMI and describe how we configured the network of spiking neuron circuits to implement the decoder and to coordinate it with the encoder in an experimental BMI paradigm that connects bidirectionally the brain of an anesthetized rat with an external object. We show that the chip learned the decoding task correctly, allowing the interfaced brain to control the object's trajectories robustly. Based on our demonstration, we propose that neuromorphic technology is mature enough for the development of BMI modules that are sufficiently low-power and compact, while being highly computationally powerful and adaptive.

Bidirectional fiber-wireless and fiber-IVLLC integrated system based on polarization-orthogonal modulation scheme.

Science.gov (United States)

Lu, Hai-Han; Li, Chung-Yi; Chen, Hwan-Wei; Ho, Chun-Ming; Cheng, Ming-Te; Huang, Sheng-Jhe; Yang, Zih-Yi; Lin, Xin-Yao

2016-07-25

A bidirectional fiber-wireless and fiber-invisible laser light communication (IVLLC) integrated system that employs polarization-orthogonal modulation scheme for hybrid cable television (CATV)/microwave (MW)/millimeter-wave (MMW)/baseband (BB) signal transmission is proposed and demonstrated. To our knowledge, it is the first one that adopts a polarization-orthogonal modulation scheme in a bidirectional fiber-wireless and fiber-IVLLC integrated system with hybrid CATV/MW/MMW/BB signal. For downlink transmission, carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple-beat (CTB), and bit error rate (BER) perform well over 40-km single-mode fiber (SMF) and 10-m RF/50-m optical wireless transport scenarios. For uplink transmission, good BER performance is obtained over 40-km SMF and 50-m optical wireless transport scenario. Such a bidirectional fiber-wireless and fiber-IVLLC integrated system for hybrid CATV/MW/MMW/BB signal transmission will be an attractive alternative for providing broadband integrated services, including CATV, Internet, and telecommunication services. It is shown to be a prominent one to present the advancements for the convergence of fiber backbone and RF/optical wireless feeder.

Development of a bi-directional standing wave linear piezoelectric actuator with four driving feet.

Science.gov (United States)

Liu, Yingxiang; Shi, Shengjun; Li, Chunhong; Chen, Weishan; Wang, Liang; Liu, Junkao

2018-03-01

A bi-directional standing wave linear piezoelectric ultrasonic actuator with four driving feet is proposed in this work. Two sandwich type transducers operated in longitudinal-bending hybrid modes are set parallelly. The working mode of the transducer is not simple hybrid vibrations of a longitudinal one and a bending one, but a special coupling vibration mode contained both longitudinal and bending components. Two transducers with the same structure and unsymmetrical boundary conditions are set parallelly to accomplish the bi-directional driving: the first transducer can push the runner forward, while the other one produces the backward driving. In the experiments, two voltages with different amplitudes are applied on the two transducers, respectively: the one with higher voltage serves as the actuator, whereas the other one applied with lower voltage is used to reduce the frictional force. The prototype achieves maximum no-load speed and thrust force of 244 mm/s and 9.8 N. This work gives a new idea for the construction of standing wave piezoelectric ultrasonic actuator with bi-directional driving ability. Copyright © 2017 Elsevier B.V. All rights reserved.

Bidirectional Relations between Temperament and Parenting Styles in Chinese Children

Science.gov (United States)

Lee, Erica H.; Zhou, Qing; Eisenberg, Nancy; Wang, Yun

2012-01-01

The present study examined bidirectional relations between child temperament and parenting styles in a sample (n = 425) of Chinese children during elementary school period (age range = 6 to 9 years at Wave 1). Using two waves (3.8 years apart) of longitudinal data, we tested two hypotheses: (1) whether child temperament (effortful control and anger/frustration) at Wave 1 predicts parenting styles (authoritative and authoritarian parenting) at Wave 2, controlling for Wave 1 parenting; and (2) whether parenting styles at Wave 1 predict Wave 2 temperament, controlling for Wave 1 temperament. We found support for bidirectional relations between temperament and authoritarian parenting, such that higher effortful control and lower anger/frustration were associated with higher authoritarian parenting across time and in both directions. There were no significant cross-time associations between children’s temperament and authoritative parenting. These findings extend the previous tests of transactional relations between child temperament and parenting in Chinese children and are consistent with the cultural values toward effortful control and control of anger/frustration in Chinese society. PMID:23482684

Bidirectional Relations between Temperament and Parenting Styles in Chinese Children.

Science.gov (United States)

Lee, Erica H; Zhou, Qing; Eisenberg, Nancy; Wang, Yun

2013-01-01

The present study examined bidirectional relations between child temperament and parenting styles in a sample ( n = 425) of Chinese children during elementary school period (age range = 6 to 9 years at Wave 1). Using two waves (3.8 years apart) of longitudinal data, we tested two hypotheses: (1) whether child temperament (effortful control and anger/frustration) at Wave 1 predicts parenting styles (authoritative and authoritarian parenting) at Wave 2, controlling for Wave 1 parenting; and (2) whether parenting styles at Wave 1 predict Wave 2 temperament, controlling for Wave 1 temperament. We found support for bidirectional relations between temperament and authoritarian parenting, such that higher effortful control and lower anger/frustration were associated with higher authoritarian parenting across time and in both directions. There were no significant cross-time associations between children's temperament and authoritative parenting. These findings extend the previous tests of transactional relations between child temperament and parenting in Chinese children and are consistent with the cultural values toward effortful control and control of anger/frustration in Chinese society.

Imaging the spectral reflectance properties of bipolar radiofrequency-fused bowel tissue

Science.gov (United States)

Clancy, Neil T.; Arya, Shobhit; Stoyanov, Danail; Du, Xiaofei; Hanna, George B.; Elson, Daniel S.

2015-07-01

Delivery of radiofrequency (RF) electrical energy is used during surgery to heat and seal tissue, such as vessels, allowing resection without blood loss. Recent work has suggested that this approach may be extended to allow surgical attachment of larger tissue segments for applications such as bowel anastomosis. In a large series of porcine surgical procedures bipolar RF energy was used to resect and re-seal the small bowel in vivo with a commercial tissue fusion device (Ligasure; Covidien PLC, USA). The tissue was then imaged with a multispectral imaging laparoscope to obtain a spectral datacube comprising both fused and healthy tissue. Maps of blood volume, oxygen saturation and scattering power were derived from the measured reflectance spectra using an optimised light-tissue interaction model. A 60% increase in reflectance of visible light (460-700 nm) was observed after fusion, with the tissue taking on a white appearance. Despite this the distinctive shape of the haemoglobin absorption spectrum was still noticeable in the 460-600 nm wavelength range. Scattering power increased in the fused region in comparison to normal serosa, while blood volume and oxygen saturation decreased. Observed fusion-induced changes in the reflectance spectrum are consistent with the biophysical changes induced through tissue denaturation and increased collagen cross-linking. The multispectral imager allows mapping of the spatial extent of these changes and classification of the zone of damaged tissue. Further analysis of the spectral data in parallel with histopathological examination of excised specimens will allow correlation of the optical property changes with microscopic alterations in tissue structure.

Hormone response to bidirectional selection on social behavior.

Science.gov (United States)

Amdam, Gro V; Page, Robert E; Fondrk, M Kim; Brent, Colin S

2010-01-01

Behavior is a quantitative trait determined by multiple genes. Some of these genes may have effects from early development and onward by influencing hormonal systems that are active during different life-stages leading to complex associations, or suites, of traits. Honey bees (Apis mellifera) have been used extensively in experiments on the genetic and hormonal control of complex social behavior, but the relationships between their early developmental processes and adult behavioral variation are not well understood. Bidirectional selective breeding on social food-storage behavior produced two honey bee strains, each with several sublines, that differ in an associated suite of anatomical, physiological, and behavioral traits found in unselected wild type bees. Using these genotypes, we document strain-specific changes during larval, pupal, and early adult life-stages for the central insect hormones juvenile hormone (JH) and ecdysteroids. Strain differences correlate with variation in female reproductive anatomy (ovary size), which can be influenced by JH during development, and with secretion rates of ecdysteroid from the ovaries of adults. Ovary size was previously assigned to the suite of traits of honey bee food-storage behavior. Our findings support that bidirectional selection on honey bee social behavior acted on pleiotropic gene networks. These networks may bias a bee's adult phenotype by endocrine effects on early developmental processes that regulate variation in reproductive traits. © 2010 Wiley Periodicals, Inc.

Color coded multiple access scheme for bidirectional multiuser visible light communications in smart home technologies

Science.gov (United States)

Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon-Ho

2015-10-01

In optical wireless communications, multiple channel transmission is an attractive solution to enhancing capacity and system performance. A new modulation scheme called color coded multiple access (CCMA) for bidirectional multiuser visible light communications (VLC) is presented for smart home applications. The proposed scheme uses red, green and blue (RGB) light emitting diodes (LED) for downlink and phosphor based white LED (P-LED) for uplink to establish a bidirectional VLC and also employs orthogonal codes to support multiple users and devices. The downlink transmission for data user devices and smart home devices is provided using red and green colors from the RGB LEDs, respectively, while uplink transmission from both types of devices is performed using the blue color from P-LEDs. Simulations are conducted to verify the performance of the proposed scheme. It is found that the proposed bidirectional multiuser scheme is efficient in terms of data rate and performance. In addition, since the proposed scheme uses RGB signals for downlink data transmission, it provides flicker-free illumination that would lend itself to multiuser VLC system for smart home applications.

Distributed fiber Raman amplification in long reach PON bidirectional access links

DEFF Research Database (Denmark)

Tafur Monroy, Idelfonso; Kjær, Rasmus; Öhman, Filip

2008-01-01

Distributed Raman fiber amplification is proposed and experimentally demonstrated to support long reach passive optical network (PON) links. An 80 km, bidirectional, single fiber link is demonstrated using both standard intensity optical modulators at 10 Gb/s and up to 7.5 Gb/s using novel...

Comparative evaluation of soft-switching, bidirectional, isolated AC/DC converter topologies

NARCIS (Netherlands)

Everts, J.; Krismer, F.; Van den Keybus, J.; Driesen, Johan; Kolar, J.W.

2012-01-01

For realizing bidirectional and isolated AC/DC converters, soft-switching techniques/topologies seem to be a favourable choice as they enable a further loss and volume reduction of the system. Contrary to the traditional dual-stage approach, using a power factor corrector (PFC) stage in series with

Do sensitive parents foster kind children, or vice versa? Bidirectional influences between children's prosocial behavior and parental sensitivity.

Science.gov (United States)

Newton, Emily K; Laible, Deborah; Carlo, Gustavo; Steele, Joel S; McGinley, Meredith

2014-06-01

Bidirectional theories of social development have been around for over 40 years (Bell, 1968), yet they have been applied primarily to the study of antisocial development. In the present study, the reciprocal relationship between parenting behavior and children's socially competent behaviors were examined. Using the National Institute of Child Health and Development Study of Early Child Care data set (NICHD Early Child Care Research Network, 2005), bidirectional relationships between parental sensitivity and children's prosocial behavior were modeled using latent variables in structural equation modeling for mothers and fathers, separately. Children and their parents engaged in structured interactions when children were 54-month-olds, 3rd graders, and 5th graders, and these interactions were coded for parental sensitivity. At 3rd, 5th, and 6th grades, teachers and parents reported on children's prosocial behavior. Parental education and child gender were entered as covariates in the models. The results provide support for a bidirectional relationship between children's prosocial behavior and maternal sensitivity (but not paternal sensitivity) in middle childhood. The importance of using a bidirectional approach to examine the development of social competence is emphasized. PsycINFO Database Record (c) 2014 APA, all rights reserved.

A Novel User Created Message Application Service Design for Bidirectional TPEG

Science.gov (United States)

Lee, Sang-Hee; Jo, Kang-Hyun

The T-DMB (Terrestrial-Digital Multimedia Broadcasting) is the national service, currently successful in use in Korea since 2008. Among other services, TPEG (Transport Protocol Experts Group) service has been spotlighted in the aspects of creating earnings. At present, TPEG service is not so popular as it fails to satisfy the user’s demands on various aspects. Thus, the variety of services including bidirectional service is necessary in stage of DMB2.0. In this paper, the limitations of existing TPEG-POI (Point of Interest) application service using the wireless communication network are indicated. To overcome such limitations, we propose a business model for TPEG-UCM (User Created Message) application service which uses individual bidirectional media. The experiment shown in this paper proves the usability and operability of the proposed method, suggesting that the implementation of the proposed method would be overcome a lack of variety and unidirectional of existing TPEG application.

Aplikasi Bidirectional Assosiatif Memori (BAM) Network pada Pengenalan Model

OpenAIRE

Iskandar, Iskhaq

2001-01-01

Penelitian ini bertujuan untuk menyusun suatu simulasi komputer yang dapat dipergunakan untuk menguji kemampuan memori komputer dalam mengenali suatu model tertentu berdasarkan algoritma Bidirectional Assosiatif Memori Neural Network. Model yang digunakan dalam penelitian dalam penelitian ini adalah huruf-huruf abjad yang dinyatakan dalam kode polar –1 dan +1 dalam bentuk matrik [5x3]. Hasil yang didapat dalam penelitian ini menunjukkan bahwa rancangan network yang disusun mampu mengenali mod...

Predistortion of a Bidirectional Cuk Audio Amplifier

DEFF Research Database (Denmark)

Birch, Thomas Hagen; Nielsen, Dennis; Knott, Arnold

2014-01-01

Some non-linear amplifier topologies are capable of providing a larger voltage gain than one from a DC source, which could make them suitable for various applications. However, the non-linearities introduce a significant amount of harmonic distortion (THD). Some of this distortion could be reduced...... using predistortion. This paper suggests linearizing a nonlinear bidirectional Cuk audio amplifier using an analog predistortion approach. A prototype power stage was built and results show that a voltage gain of up to 9 dB and reduction in THD from 6% down to 3% was obtainable using this approach....

Multistability in bidirectional associative memory neural networks

International Nuclear Information System (INIS)

Huang Gan; Cao Jinde

2008-01-01

In this Letter, the multistability issue is studied for Bidirectional Associative Memory (BAM) neural networks. Based on the existence and stability analysis of the neural networks with or without delay, it is found that the 2n-dimensional networks can have 3 n equilibria and 2 n equilibria of them are locally exponentially stable, where each layer of the BAM network has n neurons. Furthermore, the results has been extended to (n+m)-dimensional BAM neural networks, where there are n and m neurons on the two layers respectively. Finally, two numerical examples are presented to illustrate the validity of our results

Multistability in bidirectional associative memory neural networks

Science.gov (United States)

Huang, Gan; Cao, Jinde

2008-04-01

In this Letter, the multistability issue is studied for Bidirectional Associative Memory (BAM) neural networks. Based on the existence and stability analysis of the neural networks with or without delay, it is found that the 2 n-dimensional networks can have 3 equilibria and 2 equilibria of them are locally exponentially stable, where each layer of the BAM network has n neurons. Furthermore, the results has been extended to (n+m)-dimensional BAM neural networks, where there are n and m neurons on the two layers respectively. Finally, two numerical examples are presented to illustrate the validity of our results.

Multi-user bidirectional communication using isochronal synchronisation of array of chaotic directly modulated semiconductor lasers

International Nuclear Information System (INIS)

Krishna, Bindu M.; John, Manu P.; Nandakumaran, V.M.

2010-01-01

Isochronal synchronisation between the elements of an array of three mutually coupled directly modulated semiconductor lasers is utilized for the purpose of simultaneous bidirectional secure communication. Chaotic synchronisation is achieved by adding the coupling signal to the self feedback signal provided to each element of the array. A symmetric coupling is effective in inducing synchronisation between the elements of the array. This coupling scheme provides a direct link between every pair of elements thus making the method suitable for simultaneous bidirectional communication between them. Both analog and digital messages are successfully encrypted and decrypted simultaneously by each element of the array.

Efficient parallel and out of core algorithms for constructing large bi-directed de Bruijn graphs

Directory of Open Access Journals (Sweden)

Vaughn Matthew

2010-11-01

Full Text Available Abstract Background Assembling genomic sequences from a set of overlapping reads is one of the most fundamental problems in computational biology. Algorithms addressing the assembly problem fall into two broad categories - based on the data structures which they employ. The first class uses an overlap/string graph and the second type uses a de Bruijn graph. However with the recent advances in short read sequencing technology, de Bruijn graph based algorithms seem to play a vital role in practice. Efficient algorithms for building these massive de Bruijn graphs are very essential in large sequencing projects based on short reads. In an earlier work, an O(n/p time parallel algorithm has been given for this problem. Here n is the size of the input and p is the number of processors. This algorithm enumerates all possible bi-directed edges which can overlap with a node and ends up generating Θ(nΣ messages (Σ being the size of the alphabet. Results In this paper we present a Θ(n/p time parallel algorithm with a communication complexity that is equal to that of parallel sorting and is not sensitive to Σ. The generality of our algorithm makes it very easy to extend it even to the out-of-core model and in this case it has an optimal I/O complexity of Θ(nlog(n/BBlog(M/B (M being the main memory size and B being the size of the disk block. We demonstrate the scalability of our parallel algorithm on a SGI/Altix computer. A comparison of our algorithm with the previous approaches reveals that our algorithm is faster - both asymptotically and practically. We demonstrate the scalability of our sequential out-of-core algorithm by comparing it with the algorithm used by VELVET to build the bi-directed de Bruijn graph. Our experiments reveal that our algorithm can build the graph with a constant amount of memory, which clearly outperforms VELVET. We also provide efficient algorithms for the bi-directed chain compaction problem. Conclusions The bi-directed

Efficient parallel and out of core algorithms for constructing large bi-directed de Bruijn graphs.

Science.gov (United States)

Kundeti, Vamsi K; Rajasekaran, Sanguthevar; Dinh, Hieu; Vaughn, Matthew; Thapar, Vishal

2010-11-15

Assembling genomic sequences from a set of overlapping reads is one of the most fundamental problems in computational biology. Algorithms addressing the assembly problem fall into two broad categories - based on the data structures which they employ. The first class uses an overlap/string graph and the second type uses a de Bruijn graph. However with the recent advances in short read sequencing technology, de Bruijn graph based algorithms seem to play a vital role in practice. Efficient algorithms for building these massive de Bruijn graphs are very essential in large sequencing projects based on short reads. In an earlier work, an O(n/p) time parallel algorithm has been given for this problem. Here n is the size of the input and p is the number of processors. This algorithm enumerates all possible bi-directed edges which can overlap with a node and ends up generating Θ(nΣ) messages (Σ being the size of the alphabet). In this paper we present a Θ(n/p) time parallel algorithm with a communication complexity that is equal to that of parallel sorting and is not sensitive to Σ. The generality of our algorithm makes it very easy to extend it even to the out-of-core model and in this case it has an optimal I/O complexity of Θ(nlog(n/B)Blog(M/B)) (M being the main memory size and B being the size of the disk block). We demonstrate the scalability of our parallel algorithm on a SGI/Altix computer. A comparison of our algorithm with the previous approaches reveals that our algorithm is faster--both asymptotically and practically. We demonstrate the scalability of our sequential out-of-core algorithm by comparing it with the algorithm used by VELVET to build the bi-directed de Bruijn graph. Our experiments reveal that our algorithm can build the graph with a constant amount of memory, which clearly outperforms VELVET. We also provide efficient algorithms for the bi-directed chain compaction problem. The bi-directed de Bruijn graph is a fundamental data structure for

Partner Effects and Bi-Directional Parent-Child Effects in Family Alcohol Use

NARCIS (Netherlands)

Otten, R.; van der Zwaluw, C.S.; Vorst, H.; Engels, R.C.M.E.

2008-01-01

Introduction: The current study investigated partner effects and bidirectional parent-child effects in family alcohol use. Methods: A full family, longitudinal design was used to test the hypotheses. Participants were 428 families, including mothers, fathers, and 2 children. Associations were

Helical solutions of the bidirectional vortex in a cylindrical cyclone: Beltramian and Trkalian motions

International Nuclear Information System (INIS)

Majdalani, Joseph

2012-01-01

In this work, two families of helical motions are investigated as prospective candidates for describing the bidirectional vortex field in a right-cylindrical chamber. These basic solutions are relevant to cyclone separators and to idealized representations of vortex-fired liquid and hybrid rocket engines in which bidirectional vortex motion is established. To begin, the bulk fluid motion is taken to be isentropic along streamlines, with no concern for reactions, heat transfer, viscosity, compressibility or unsteadiness. Then using the Bragg–Hawthorne equation for steady, inviscid, axisymmetric motion, two families of Euler solutions are derived. Among the characteristics of the newly developed solutions one may note the axial dependence of the swirl velocity, the Trkalian and Beltramian types of the helical motions, the sensitivity of the solutions to the outlet radius, the alternate locations of the mantle, and the increased axial and radial velocity magnitudes, including the rate of mass transfer across the mantle, for which explicit approximations are obtained. Our results are compared to an existing, complex lamellar model of the bidirectional vortex in which the swirl velocity reduces to a free vortex. In this vein, we find the strictly Beltramian flows to share virtually identical pressure variations and radial pressure gradients with those associated with the complex lamellar motion. Furthermore, both families warrant an asymptotic treatment to overcome their endpoint limitations caused by their omission of viscous stresses. From a broader perspective, the work delineates a logical framework through which self-similar, axisymmetric solutions to bidirectional and multidirectional vortex motions may be pursued. It also illustrates the manner through which different formulations may be arrived at depending on the types of wall boundary conditions. For example, both the slip condition at the sidewall and the inlet flow pattern at the headwall may be enforced

Helical solutions of the bidirectional vortex in a cylindrical cyclone: Beltramian and Trkalian motions

Energy Technology Data Exchange (ETDEWEB)

Majdalani, Joseph, E-mail: joe.majdalani@gmail.com [Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee Space Institute (UTSI), 411 B. H. Goethert Parkway, Tullahoma, TN 37388 (United States)

2012-10-15

In this work, two families of helical motions are investigated as prospective candidates for describing the bidirectional vortex field in a right-cylindrical chamber. These basic solutions are relevant to cyclone separators and to idealized representations of vortex-fired liquid and hybrid rocket engines in which bidirectional vortex motion is established. To begin, the bulk fluid motion is taken to be isentropic along streamlines, with no concern for reactions, heat transfer, viscosity, compressibility or unsteadiness. Then using the Bragg-Hawthorne equation for steady, inviscid, axisymmetric motion, two families of Euler solutions are derived. Among the characteristics of the newly developed solutions one may note the axial dependence of the swirl velocity, the Trkalian and Beltramian types of the helical motions, the sensitivity of the solutions to the outlet radius, the alternate locations of the mantle, and the increased axial and radial velocity magnitudes, including the rate of mass transfer across the mantle, for which explicit approximations are obtained. Our results are compared to an existing, complex lamellar model of the bidirectional vortex in which the swirl velocity reduces to a free vortex. In this vein, we find the strictly Beltramian flows to share virtually identical pressure variations and radial pressure gradients with those associated with the complex lamellar motion. Furthermore, both families warrant an asymptotic treatment to overcome their endpoint limitations caused by their omission of viscous stresses. From a broader perspective, the work delineates a logical framework through which self-similar, axisymmetric solutions to bidirectional and multidirectional vortex motions may be pursued. It also illustrates the manner through which different formulations may be arrived at depending on the types of wall boundary conditions. For example, both the slip condition at the sidewall and the inlet flow pattern at the headwall may be enforced or

An Improved Multidimensional MPA Procedure for Bidirectional Earthquake Excitations

Directory of Open Access Journals (Sweden)

Feng Wang

2014-01-01

Full Text Available Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two components earthquake excitations, and independent analysis in each direction is not required and the application of simplified superposition formulas is avoided. The strength reduction factor spectra based on superposition of earthquake excitations are discussed and compared with the traditional strength reduction factor spectra. The step-by-step procedure is proposed to estimate seismic demands of structures. Two examples are implemented to verify the accuracy of the method, and the results of the examples show that (1 the IMMPA method can be used to estimate the responses of structure subjected to bidirectional earthquake excitations. (2 Along with increase of peak of earthquake acceleration, structural response deviation estimated with the IMMPA method may also increase. (3 Along with increase of the number of total floors of structures, structural response deviation estimated with the IMMPA method may also increase.

The Chaotic-Based Control of Three-Port Isolated Bidirectional DC/DC Converters for Electric and Hybrid Vehicles

Directory of Open Access Journals (Sweden)

Zheng Wang

2016-01-01

Full Text Available Three-port isolated (TPI bidirectional DC/DC converters have three energy ports and offer advantages of large voltage gain, galvanic isolation ability and high power density. For this reason this kind of converters are suitable to connect different energy sources and loads in electric and hybrid vehicles. The purpose of this paper is to propose chaotic modulation and the related control scheme for TPI bidirectional DC/DC converters, in such a way that the switching harmonic peaks can be suppressed in spectrum and the conducted electromagnetic interference (EMI is reduced. Two chaotic modulation strategies, namely the continuously chaotic modulation and the discretely chaotic modulation are presented. These two chaotic modulation strategies are applied for TPI bidirectional DC/DC converters with shifted-phase angle based control and phase-shifted PWM control. Both simulation and experiments are given to verify the validity of the proposed chaotic modulation-based control schemes.

Mechanical analysis of non-uniform bi-directional functionally graded intelligent micro-beams using modified couple stress theory

Science.gov (United States)

Bakhshi Khaniki, Hossein; Rajasekaran, Sundaramoorthy

2018-05-01

This study develops a comprehensive investigation on mechanical behavior of non-uniform bi-directional functionally graded beam sensors in the framework of modified couple stress theory. Material variation is modelled through both length and thickness directions using power-law, sigmoid and exponential functions. Moreover, beam is assumed with linear, exponential and parabolic cross-section variation through the length using power-law and sigmoid varying functions. Using these assumptions, a general model for microbeams is presented and formulated by employing Hamilton’s principle. Governing equations are solved using a mixed finite element method with Lagrangian interpolation technique, Gaussian quadrature method and Wilson’s Lagrangian multiplier method. It is shown that by using bi-directional functionally graded materials in nonuniform microbeams, mechanical behavior of such structures could be affected noticeably and scale parameter has a significant effect in changing the rigidity of nonuniform bi-directional functionally graded beams.

How Can Polarization States of Reflected Light from Snow Surfaces Inform Us on Surface Normals and Ultimately Snow Grain Size Measurements?

Science.gov (United States)

Schneider, A. M.; Flanner, M.; Yang, P.; Yi, B.; Huang, X.; Feldman, D.

2016-12-01

The Snow Grain Size and Pollution (SGSP) algorithm is a method applied to Moderate Resolution Imaging Spectroradiometer data to estimate snow grain size from space-borne measurements. Previous studies validate and quantify potential sources of error in this method, but because it assumes flat snow surfaces, however, large scale variations in surface normals can cause biases in its estimates due to its dependence on solar and observation zenith angles. To address these variations, we apply the Monte Carlo method for photon transport using data containing the single scattering properties of different ice crystals to calculate polarization states of reflected monochromatic light at 1500nm from modeled snow surfaces. We evaluate the dependence of these polarization states on solar and observation geometry at 1500nm because multiple scattering is generally a mechanism for depolarization and the ice crystals are relatively absorptive at this wavelength. Using 1500nm thus results in a higher number of reflected photons undergoing fewer scattering events, increasing the likelihood of reflected light having higher degrees of polarization. In evaluating the validity of the model, we find agreement with previous studies pertaining to near-infrared spectral directional hemispherical reflectance (i.e. black-sky albedo) and similarities in measured bidirectional reflectance factors, but few studies exist modeling polarization states of reflected light from snow surfaces. Here, we present novel results pertaining to calculated polarization states and compare dependences on solar and observation geometry for different idealized snow surfaces. If these dependencies are consistent across different ice particle shapes and sizes, then these findings could inform the SGSP algorithm by providing useful relationships between measurable physical quantities and solar and observation geometry to better understand variations in snow surface normals from remote sensing observations.

Bidirectional Partner Violence among Homeless Young Adults: Risk Factors and Outcomes

Science.gov (United States)

Tyler, Kimberly A.; Melander, Lisa A.; Noel, HarmoniJoie

2009-01-01

One of the most prevalent forms of violence in contemporary society is the victimization of intimate partners. Although it has been established that homeless young people experience high levels of victimization on the street, little is known about partner violence (PV) experiences among this group, especially bidirectional violence. As such, the…

High performance bidirectional electrostatic inchworm motor fabricated by trench isolation technology

NARCIS (Netherlands)

Sarajlic, Edin; Berenschot, Johan W.; Tas, Niels Roelof; Fujita, H.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

We report on an electrostatic linear micromotor, which employs built-in mechanical leverage to convert normal deflection of a flexible plate into a small in-plane step and two clamps to enable bidirectional inchworm motion. The motor, measuring 412 /spl mu/m /spl times/ 286 /spl mu/m, is fabricated

Evaluation of BRDF Archetypes for Representing Surface Reflectance Anisotropy Using MODIS BRDF Data

Directory of Open Access Journals (Sweden)

Hu Zhang

2015-06-01

Full Text Available Bidirectional reflectance distribution function (BRDF archetypes extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS BRDF/Albedo product over the global Earth Observing System Land Validation Core Sites can be used to simplify BRDF models. The present study attempts to evaluate the representativeness of BRDF archetypes for surface reflectance anisotropy. Five-year forward-modeled MODIS multi-angular reflectance (MCD-ref and aditional actual MODIS multi-angular observations (MCD-obs in four growing periods in 2008 over three tiles were taken as validation data. First, BRDF archetypes in the principal plane were qualitatively compared with the time-series MODIS BRDF product of randomly sampled pixels. Secondly, BRDF archetypes were used to fit MCD-ref, and the average root-mean-squared errors (RMSEs over each tile were examined for these five years. Finally, both BRDF archetypes and the MODIS BRDF were used to fit MCD-obs, and the histograms of the fit-RMSEs were compared. The consistency of the directional reflectance between the BRDF archetypes and MODIS BRDFs in nadir-view, hotspot and entire viewing hemisphere at 30° and 50° solar geometries were also examined. The results confirm that BRDF archetypes are representative of surface reflectance anisotropy for available snow-free MODIS data.

Theory of reflection reflection and transmission of electromagnetic, particle and acoustic waves

CERN Document Server

Lekner, John

2016-01-01

This book deals with the reflection of electromagnetic and particle waves by interfaces. The interfaces can be sharp or diffuse. The topics of the book contain absorption, inverse problems, anisotropy, pulses and finite beams, rough surfaces, matrix methods, numerical methods,  reflection of particle waves and neutron reflection. Exact general results are presented, followed by long wave reflection, variational theory, reflection amplitude equations of the Riccati type, and reflection of short waves. The Second Edition of the Theory of Reflection is an updated and much enlarged revision of the 1987 monograph. There are new chapters on periodically stratified media, ellipsometry, chiral media, neutron reflection and reflection of acoustic waves. The chapter on anisotropy is much extended, with a complete treatment of the reflection and transmission properties of arbitrarily oriented uniaxial crystals. The book gives a systematic and unified treatment reflection and transmission of electromagnetic and particle...

Bidirectional Cardio-Respiratory Interactions in Heart Failure.

Science.gov (United States)

Radovanović, Nikola N; Pavlović, Siniša U; Milašinović, Goran; Kirćanski, Bratislav; Platiša, Mirjana M

2018-01-01

We investigated cardio-respiratory coupling in patients with heart failure by quantification of bidirectional interactions between cardiac (RR intervals) and respiratory signals with complementary measures of time series analysis. Heart failure patients were divided into three groups of twenty, age and gender matched, subjects: with sinus rhythm (HF-Sin), with sinus rhythm and ventricular extrasystoles (HF-VES), and with permanent atrial fibrillation (HF-AF). We included patients with indication for implantation of implantable cardioverter defibrillator or cardiac resynchronization therapy device. ECG and respiratory signals were simultaneously acquired during 20 min in supine position at spontaneous breathing frequency in 20 healthy control subjects and in patients before device implantation. We used coherence, Granger causality and cross-sample entropy analysis as complementary measures of bidirectional interactions between RR intervals and respiratory rhythm. In heart failure patients with arrhythmias (HF-VES and HF-AF) there is no coherence between signals ( p respiratory signal in HF-VES. Cross-sample entropy analysis revealed the strongest synchrony between respiratory and RR signal in HF-VES group. Beside respiratory sinus arrhythmia there is another type of cardio-respiratory interaction based on the synchrony between cardiac and respiratory rhythm. Both of them are altered in heart failure patients. Respiratory sinus arrhythmia is reduced in HF-Sin patients and vanished in heart failure patients with arrhythmias. Contrary, in HF-Sin and HF-VES groups, synchrony increased, probably as consequence of some dominant neural compensatory mechanisms. The coupling of cardiac and respiratory rhythm in heart failure patients varies depending on the presence of atrial/ventricular arrhythmias and it could be revealed by complementary methods of time series analysis.

On Practical Sampling of Bidirectional Reflectance

DEFF Research Database (Denmark)

Nielsen, Jannik Boll

for reconstructing full and accurate BRDFs from only a few measurements is presented. It is here demonstrated that with as little as 20 point-samples, a BRDF can accurately be reconstructed. Furthermore utilising the field of view of a camera, this may be reduced to as little as two images. With this, the thesis...

Robust stability of bidirectional associative memory neural networks with time delays

Science.gov (United States)

Park, Ju H.

2006-01-01

Based on the Lyapunov Krasovskii functionals combined with linear matrix inequality approach, a novel stability criterion is proposed for asymptotic stability of bidirectional associative memory neural networks with time delays. A novel delay-dependent stability criterion is given in terms of linear matrix inequalities, which can be solved easily by various optimization algorithms.

Robust stability of bidirectional associative memory neural networks with time delays

International Nuclear Information System (INIS)

Park, Ju H.

2006-01-01

Based on the Lyapunov-Krasovskii functionals combined with linear matrix inequality approach, a novel stability criterion is proposed for asymptotic stability of bidirectional associative memory neural networks with time delays. A novel delay-dependent stability criterion is given in terms of linear matrix inequalities, which can be solved easily by various optimization algorithms

Pre-processing of dual-view FIGOS Data: towards operational BRDF retrieval

OpenAIRE

Hueni, A; Schopfer, J; Schläpfer, D; Kneubühler, M; Nieke, J

2008-01-01

The Bidirectional Reflectance Distribution Function (BRDF) is an inherent property of natural and manmade materials. Its effects depend on the illumination/observation geometry and wavelengths and are apparent in groundbased, airborne and spaceborne imagery. The BRDF is a fundamental quantity from which all other illumination/reflection configurations can be derived. Calibration and validation of hyperspectral images requires knowledge of the BRDF if spectrodirectional effects are to be accou...

Investigations of bi-directional flow behaviour in presence of a large vertical opening in a fire compartment

International Nuclear Information System (INIS)

Sharma, Pavan K.; Gera, B.

2011-01-01

In the complex thermal hydraulics codes developed for fire, reactor and containment safety the junctions in the multi-compartment geometries are often modeled as uni-directional junctions and some construct of flow coefficient. However, certain large size junctions are known to depict bi-directional flow behaviour under specific circumstances. The CFD based computer code FDS was used for an earlier reported study of fire in an enclosure on the bidirectional flow behaviour in present of a wall opening. Numerical simulation is directed to monitor the entrainment of the fresh air from outside to the fire compartment and resulting plume deflection due to presence of a big opening. The paper presents the details of the analysis, the results obtained, and comparison with the reported experimental data in terms of plume deflection, entrainment. Detailed investigations have been carried out to understand the bi-directionality of a junction by analyzing studying the outgoing hot air flow and incoming cold air. (orig.)

Chaos synchronization communication using extremely unsymmetrical bidirectional injections.

Science.gov (United States)

Zhang, Wei Li; Pan, Wei; Luo, Bin; Zou, Xi Hua; Wang, Meng Yao; Zhou, Zhi

2008-02-01

Chaos synchronization and message transmission between two semiconductor lasers with extremely unsymmetrical bidirectional injections (EUBIs) are discussed. By using EUBIs, synchronization is realized through injection locking. Numerical results show that if the laser subjected to strong injection serves as the receiver, chaos pass filtering (CPF) of the system is similar to that of unidirectional coupled systems. Moreover, if the other laser serves as the receiver, a stronger CPF can be obtained. Finally, we demonstrate that messages can be extracted successfully from either of the two transmission directions of the system.

Applying deep bidirectional LSTM and mixture density network for basketball trajectory prediction

NARCIS (Netherlands)

Zhao, Yu; Yang, Rennong; Chevalier, Guillaume; Shah, Rajiv C.; Romijnders, Rob

2018-01-01

Data analytics helps basketball teams to create tactics. However, manual data collection and analytics are costly and ineffective. Therefore, we applied a deep bidirectional long short-term memory (BLSTM) and mixture density network (MDN) approach. This model is not only capable of predicting a

Effect of sol aging time on the anti-reflective properties of silica coatings templated with phosphoric acid

Directory of Open Access Journals (Sweden)

Wen Wen

Full Text Available Silica anti-reflective coatings have been prepared by a sol–gel dip-coating process using the sol containing phosphoric acid as a pore-forming template. The effect of the aging time of the sol on the anti-reflective properties has been investigated. The surface topography of the silica AR coatings has been characterized. With increasing sol aging time, more over-sized pores larger than 100 nm are formed in the silica coatings. These could act as scattering centers, scattering visible light and thereby lowering transmittance. The optimal aging time was identified as 1 day, and the corresponding silica coatings showed a maximum transmittance of 99.2%, representing an 8% increase compared to the bare glass substrate. Keywords: Thin films, Anti-reflective coatings, Aging, Dip-coating, Sol–gel preparation

[Experimental Methods and Result Analysis of a Variety of Spectral Reflectance Properties of the Thin Oil Film].

Science.gov (United States)

Ye, Zhou; Liu, Li; Wei, Chuan-xin; Gu, Qun; An, Ping-ao; Zhao, Yue-jiao; Yin, Da-yi

2015-06-01

In order to analysis the oil spill situation based on the obtained data in airborne aerial work, it's needed to get the spectral reflectance characteristics of the oil film of different oils and thickness as support and to select the appropriate operating band. An experiment is set up to measure the reflectance spectroscopy from ultraviolet to near-infrared for the film of five target samples, which means petrol, diesel, lubricating oil, kerosene and fossil, using spectral measurement device. The result is compared with the reflectance spectra of water in the same experimental environment, which shows that the spectral reflection characteristics of the oil film are related to the thickness and the type of the oil film. In case of the same thickness, the spectral reflectance curve of different types of film is far different, and for the same type of film, the spectral reflectance curve changes accordingly with the change of film thickness, therefore in terms of the single film, different film thickness can be distinguished by reflectance curves. It also shows that in terms of the same film thickness, the reflectance of diesel, kerosene, lubricants reaches peak around 380 nm wavelength, obviously different from the reflectance of water, and that the reflectance of crude oil is far less than that of water in more than 340 nm wavelength, and the obtained reflection spectrum can be used to distinguish between different types of oil film to some extent. The experiment covers main types of spilled oil, with data comprehensively covering commonly used detect spectral bands, and quantitative description of the spectral reflectance properties of film. It provides comprehensive theoretical and data support for the selection of airborne oil spill detection working band and the detection and analysis of water-surface oil spill.

Near zero reflection by nanostructured anti-reflection coating design for Si substrates

Science.gov (United States)

Al-Fandi, Mohamed; Makableh, Yahia F.; Khasawneh, Mohammad; Rabady, Rabi

2018-05-01

The nanostructure design of near zero reflection coating for Si substrates by using ZnO Nanoneedles (ZnONN) is performed and optimized for the visible spectral range. The design investigates the ZnONN tip to body ratio effect on the anti-reflection coating properties. Different tip to body ratios are used on Si substrates. Around zero reflection is achieved by the Nanoneedles structure design presented in this work, leading to minimal reflection losses from the Si surface. The current design evolves a solution to optical losses and surface contamination effects associated with Si solar cells.

Reflection electron energy loss spectroscopy as efficient technique for the determination of optical properties of polystyrene intermixed with gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Deris, Jamileh [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Hajati, Shaaker, E-mail: Hajati@mail.yu.ac.ir [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Department of Semiconductors, Materials and Energy Research Center, Karaj 3177983634 (Iran, Islamic Republic of)

2017-01-15

Highlights: • Reflection Electron Energy Loss Spectroscopy of nano-metalized polymer. • Determination of real part of the dielectric function of nanostructured sample. • Determination of imaginary part of the dielectric function of nanostructured sample. • Determination of refractive index and coefficient of extinction of the sample. • Determination of reflection and absorption coefficients of nano-metalized Polymer. - Abstract: The electronic properties (electron inelastic cross section, energy loss function) of a nano-metalized polystyrene obtained by reflection electron energy loss spectroscopy (REELS) in a previous study [J. Deris, S. Hajati, S. Tougaard, V. Zaporojtchenko, Appl. Surf. Sci. 377 (2016) 44–47], which relies on the Yubero-Tougaard method, were used in the complementary application of Kramers-Kronig transformation to determine its optical properties such as the real part (ε{sub 1}) and imaginary part (ε{sub 2}) of the dielectric function (ε), refractive index (n), coefficients of extinction (k), reflection (R) and absorption (μ). The degree of intermixing of polystyrene thin film and gold nanoparticles of sizes 5.5 nm was controlled by annealing the sample to achieve a morphology in which the nanoparticles were homogeneously distributed within polystyrene. It is worth noting that no data are available on the optical properties of metalized polymers such as gold nanoparticles intermixed with polystyrene. Therefore, this work is of high importance in terms of both the sample studied here and the method applied. The advantage of the method applied here is that no information on the lateral distribution of the nanocomposite sample is required. This means that the REELS technique has been presented here to suitably, efficiently and easily obtain the optical properties of such nano-metalized polymer in which the metal nanoparticles have been vertically well distributed (homogeneous in depth). Therefore, for vertically homogeneous and

Automatic Detection of Respiratory Events During Sleep Using Bidirectional LSTM Networks

DEFF Research Database (Denmark)

Jacobsen, K. P.; Olesen, Alexander Neergaard; Trap, L.

2018-01-01

seconds overlap. Two models were developed based on bidirectional long short-term memory (bLSTM) neural networks: 1)a two-class model for classification of windows as “normal” or “event”, and 2)a four-class model for classification as “normal”, “obstructive”, “central”, or “mixed”. 1882 subjects were used...

Variability in Surface BRDF at Different Spatial Scales (30m-500m) Over a Mixed Agricultural Landscape as Retrieved from Airborne and Satellite Spectral Measurements

Science.gov (United States)

Roman, Miguel O.; Gatebe, Charles K.; Schaaf, Crystal B.; Poudyal, Rajesh; Wang, Zhuosen; King, Michael D.

2012-01-01

Over the past decade, the role of multiangle 1 remote sensing has been central to the development of algorithms for the retrieval of global land surface properties including models of the bidirectional reflectance distribution function (BRDF), albedo, land cover/dynamics, burned area extent, as well as other key surface biophysical quantities represented by the anisotropic reflectance characteristics of vegetation. In this study, a new retrieval strategy for fine-to-moderate resolution multiangle observations was developed, based on the operational sequence used to retrieve the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 reflectance and BRDF/albedo products. The algorithm makes use of a semiempirical kernel-driven bidirectional reflectance model to provide estimates of intrinsic albedo (i.e., directional-hemispherical reflectance and bihemispherical reflectance), model parameters describing the BRDF, and extensive quality assurance information. The new retrieval strategy was applied to NASA's Cloud Absorption Radiometer (CAR) data acquired during the 2007 Cloud and Land Surface Interaction Campaign (CLASIC) over the well-instrumented Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site in Oklahoma, USA. For the case analyzed, we obtained approx.1.6 million individual surface bidirectional reflectance factor (BRF) retrievals, from nadir to 75deg off-nadir, and at spatial resolutions ranging from 3 m - 500 m. This unique dataset was used to examine the interaction of the spatial and angular 18 characteristics of a mixed agricultural landscape; and provided the basis for detailed assessments of: (1) the use of a priori knowledge in kernel-driven BRDF model inversions; (2) the interaction between surface reflectance anisotropy and instrument spatial resolution; and (3) the uncertainties that arise when sub-pixel differences in the BRDF are aggregated to a moderate resolution satellite

Developmental trajectories of irritability and bidirectional associations with maternal depression.

Science.gov (United States)

Wiggins, Jillian Lee; Mitchell, Colter; Stringaris, Argyris; Leibenluft, Ellen

2014-11-01

Irritability is a dimensional trait in typical development and a common presenting symptom in many psychiatric disorders, including depression. However, little is known about the developmental trajectory of irritability or how child irritability interacts with maternal depression. The present study identifies classes of irritability trajectories from toddlerhood to middle childhood; characterizes maternal depression and other family, social environment, and child variables within each irritability trajectory class; and, as a more exploratory analysis, examines bidirectional associations between maternal depression and child irritability. A total of 4,898 families from the Fragile Families and Child Wellbeing Study reported on irritability symptoms at ages 3, 5, and 9 years, assessed with items from the Child Behavior Checklist. Parental major depressive episode was assessed using the Composite International Diagnostic Interview-Short Form at child ages 1, 3, 5, and 9 years. A latent class growth analysis identified 5 irritability classes: low decreasing; moderate decreasing; high steady; initially very high, then decreasing; and high increasing. Children with more severe irritability trajectories are more likely to have mothers with recurrent depression, and, with the exception of the most severe (high increasing irritability) class, were more likely to have mothers who were exposed to violence. Moreover, paternal depression and alcohol abuse, as well as maternal drug and alcohol abuse, were also risk factors for membership in the more severe irritability classes. A latent auto-regressive cross-lag model showed that child irritability at ages 3 and 5 years is associated with increased mother depression at ages 5 and 9, respectively. Conversely, mother depression at child ages 1 and 3 years is associated with increased child irritability at 3 and 5. Irritability development across toddlerhood and middle childhood has 5 main trajectory types, which differ on maternal

Normalization of multidirectional red and NIR reflectances with the SAVI

Science.gov (United States)

Huete, A. R.; Hua, G.; Qi, J.; Chehbouni, A.; Van Leeuwen, W. J. D.

1992-01-01

Directional reflectance measurements were made over a semi-desert gramma grassland at various times of the growing season. View angle measurements from +40 to -40 degrees were made at various solar zenith angles and soil moisture conditions. The sensitivity of the Normalized Difference Vegetation Index (NDVI) and the Soil Adjusted Vegetation Index (SAVI) to bidirectional measurements was assessed for purposes of improving remote temporal monitoring of vegetation dynamics. The SAVI view angle response was found to be symmetric about nadir while the NDVI response was strongly anisotropic. This enabled the view angle behavior of the SAVI to be normalized with a cosine function. In contrast to the NDVI, the SAVI was able to minimize soil moisture and shadow influences for all measurement conditions.

Synchronization of a Class of Memristive Stochastic Bidirectional Associative Memory Neural Networks with Mixed Time-Varying Delays via Sampled-Data Control

Directory of Open Access Journals (Sweden)

Manman Yuan

2018-01-01

Full Text Available The paper addresses the issue of synchronization of memristive bidirectional associative memory neural networks (MBAMNNs with mixed time-varying delays and stochastic perturbation via a sampled-data controller. First, we propose a new model of MBAMNNs with mixed time-varying delays. In the proposed approach, the mixed delays include time-varying distributed delays and discrete delays. Second, we design a new method of sampled-data control for the stochastic MBAMNNs. Traditional control methods lack the capability of reflecting variable synaptic weights. In this paper, the methods are carefully designed to confirm the synchronization processes are suitable for the feather of the memristor. Third, sufficient criteria guaranteeing the synchronization of the systems are derived based on the derive-response concept. Finally, the effectiveness of the proposed mechanism is validated with numerical experiments.

Bi-directional triplexer with butterfly MMI coupler using SU-8 polymer waveguides

Science.gov (United States)

Mareš, David; Jeřábek, Vítězslav; Prajzler, Václav

2015-01-01

We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.

Cost-effective bidirectional digitized radio-over-fiber systems employing sigma delta modulation

Science.gov (United States)

Lee, Kyung Woon; Jung, HyunDo; Park, Jung Ho

2016-11-01

We propose a cost effective digitized radio-over-fiber (D-RoF) system employing a sigma delta modulation (SDM) and a bidirectional transmission technique using phase modulated downlink and intensity modulated uplink. SDM is transparent to different radio access technologies and modulation formats, and more suitable for a downlink of wireless system because a digital to analog converter (DAC) can be avoided at the base station (BS). Also, Central station and BS share the same light source by using a phase modulation for the downlink and an intensity modulation for the uplink transmission. Avoiding DACs and light sources have advantages in terms of cost reduction, power consumption, and compatibility with conventional wireless network structure. We have designed a cost effective bidirectional D-RoF system using a low pass SDM and measured the downlink and uplink transmission performance in terms of error vector magnitude, signal spectra, and constellations, which are based on the 10MHz LTE 64-QAM standard.

The Role of PTSD in Bi-directional Intimate Partner Violence in Military and Veteran Populations: A Research Review

Directory of Open Access Journals (Sweden)

Gabriela Misca

2017-08-01

Full Text Available Evidence supporting the higher prevalence of PTSD linked to combat-related trauma in military personnel and veteran populations is well-established. Consequently, much research has explored the effects that combat related trauma and the subsequent PTSD may have on different aspects of relationship functioning and adjustment. In particular, PTSD in military and veterans has been linked with perpetrating intimate partner violence (IPV. New research and theoretical perspectives suggest that in order to respond effectively to IPV, a more accurate understanding of the direction of the violence experienced within each relationship is critical. In both civilian and military populations, research that has examined the direction of IPV's, bi-directional violence have been found to be highly prevalent. Evidence is also emerging as to how these bi-directional violence differ in relation to severity, motivation, physical and psychological consequences and risk factors. Of particular importance within military IPV research is the need to deepen understanding about the role of PTSD in bi-directional IPV not only as a risk factor for perpetration but also as a vulnerability risk factor for victimization, as findings from recent research suggest. This paper provides a timely, critical review of emergent literature to disentangle what is known about bi-directional IPV patterns in military and veteran populations and the roles that military or veterans' PTSD may play within these patterns. Although, this review aimed to identify global research on the topic, the majority of research meeting the inclusion criteria was from US, with only one study identified from outside, from Canada. Strengths and limitations in the extant research are identified. Directions for future research are proposed with a particular focus on the kinds of instruments and designs needed to better capture the complex interplay of PTSD and bi-directional IPV in military populations and

Evolutionary Pseudo-Relaxation Learning Algorithm for Bidirectional Associative Memory

Institute of Scientific and Technical Information of China (English)

Sheng-Zhi Du; Zeng-Qiang Chen; Zhu-Zhi Yuan

2005-01-01

This paper analyzes the sensitivity to noise in BAM (Bidirectional Associative Memory), and then proves the noise immunity of BAM relates not only to the minimum absolute value of net inputs (MAV) but also to the variance of weights associated with synapse connections. In fact, it is a positive monotonically increasing function of the quotient of MAV divided by the variance of weights. Besides, the performance of pseudo-relaxation method depends on learning parameters (λ and ζ), but the relation of them is not linear. So it is hard to find a best combination of λ and ζ which leads to the best BAM performance. And it is obvious that pseudo-relaxation is a kind of local optimization method, so it cannot guarantee to get the global optimal solution. In this paper, a novel learning algorithm EPRBAM (evolutionary psendo-relaxation learning algorithm for bidirectional association memory) employing genetic algorithm and pseudo-relaxation method is proposed to get feasible solution of BAM weight matrix. This algorithm uses the quotient as the fitness of each individual and employs pseudo-relaxation method to adjust individual solution when it does not satisfy constraining condition any more after genetic operation. Experimental results show this algorithm improves noise immunity of BAM greatly. At the same time, EPRBAM does not depend on learning parameters and can get global optimal solution.

The Bidirectional Relationship between Sleep and Immunity against Infections

Directory of Open Access Journals (Sweden)

Elizabeth G. Ibarra-Coronado

2015-01-01

Full Text Available Sleep is considered an important modulator of the immune response. Thus, a lack of sleep can weaken immunity, increasing organism susceptibility to infection. For instance, shorter sleep durations are associated with a rise in suffering from the common cold. The function of sleep in altering immune responses must be determined to understand how sleep deprivation increases the susceptibility to viral, bacterial, and parasitic infections. There are several explanations for greater susceptibility to infections after reduced sleep, such as impaired mitogenic proliferation of lymphocytes, decreased HLA-DR expression, the upregulation of CD14+, and variations in CD4+ and CD8+ T lymphocytes, which have been observed during partial sleep deprivation. Also, steroid hormones, in addition to regulating sexual behavior, influence sleep. Thus, we hypothesize that sleep and the immune-endocrine system have a bidirectional relationship in governing various physiological processes, including immunity to infections. This review discusses the evidence on the bidirectional effects of the immune response against viral, bacterial, and parasitic infections on sleep patterns and how the lack of sleep affects the immune response against such agents. Because sleep is essential in the maintenance of homeostasis, these situations must be adapted to elicit changes in sleep patterns and other physiological parameters during the immune response to infections to which the organism is continuously exposed.

Real-time dual-comb spectroscopy with a free-running bidirectionally mode-locked fiber laser

Science.gov (United States)

Mehravar, S.; Norwood, R. A.; Peyghambarian, N.; Kieu, K.

2016-06-01

Dual-comb technique has enabled exciting applications in high resolution spectroscopy, precision distance measurements, and 3D imaging. Major advantages over traditional methods can be achieved with dual-comb technique. For example, dual-comb spectroscopy provides orders of magnitude improvement in acquisition speed over standard Fourier-transform spectroscopy while still preserving the high resolution capability. Wider adoption of the technique has, however, been hindered by the need for complex and expensive ultrafast laser systems. Here, we present a simple and robust dual-comb system that employs a free-running bidirectionally mode-locked fiber laser operating at telecommunication wavelength. Two femtosecond frequency combs (with a small difference in repetition rates) are generated from a single laser cavity to ensure mutual coherent properties and common noise cancellation. As the result, we have achieved real-time absorption spectroscopy measurements without the need for complex servo locking with accurate frequency referencing, and relatively high signal-to-noise ratio.

Airborne spectral measurements of surface anisotropy during SCAR-B

Science.gov (United States)

Tsay, Si-Chee; King, Michael D.; Arnold, G. Thomas; Li, Jason Y.

1998-12-01

During the Smoke, Clouds, and Radiation-Brazil (SCAR-B) deployment, angular distributions of spectral reflectance for vegetated surfaces and smoke layers were measured using the scanning cloud absorption radiometer (CAR) mounted on the University of Washington C-131A research aircraft. The CAR contains 13 narrowband spectral channels between 0.3 and 2.3 μm with a 190° scan aperture (5° before zenith to 5° past nadir) and 1° instantaneous field of view. The bidirectional reflectance is obtained by flying a clockwise circular orbit above the surface, resulting in a ground track ˜3 km in diameter within about 2 min. Although the CAR measurements are contaminated by minor atmospheric effects, results show distinct spectral characteristics for various types of surfaces. Spectral bidirectional reflectances of three simple and well-defined surfaces are presented: cerrado (August 18, 1995) and dense forest (August 25, 1995), both measured in Brazil under nearly clear-sky conditions, and thick smoke layers over dense forest (September 6 and 11, 1995). The bidirectional reflectances of cerrado and dense forest revealed fairly symmetric patterns along the principal plane, with varying maximal strengths and widths spectrally in the backscattering direction. In the shortwave-infrared region the aerosol effect is very small due to low spectral optical depth. Also, these backscattering maxima can be seen on the bidirectional reflectance of smoke layer over dense forest. These detailed measurements of the angular distribution of spectral reflectance can be parameterized by a few independent variables and utilized to retrieve either surface characteristics or aerosol microphysical and optical properties (e.g., size distribution and single-scattering parameters), if proper physical and radiation models are used. The spectral-hemispherical albedo of these surfaces is obtained directly by integrating all angular measurements and is compared with the measured nadir reflectance

Stable isotopes of Hawaiian spiders reflect substrate properties along a chronosequence

Science.gov (United States)

Dawson, Todd E.; Gillespie, Rosemary G.

2018-01-01

The Hawaiian Islands offer a unique opportunity to test how changes in the properties of an isolated ecosystem are propagated through the organisms that occur within that ecosystem. The age-structured arrangement of volcanic-derived substrates follows a regular progression over space and, by inference, time. We test how well documented successional changes in soil chemistry and associated vegetation are reflected in organisms at higher trophic levels—specifically, predatory arthropods (spiders)—across a range of functional groups. We focus on three separate spider lineages: one that builds capture webs, one that hunts actively, and one that specializes on eating other spiders. We analyze spiders from three sites across the Hawaiian chronosequence with substrate ages ranging from 200 to 20,000 years. To measure the extent to which chemical signatures of terrestrial substrates are propagated through higher trophic levels, we use standard stable isotope analyses of nitrogen and carbon, with plant leaves included as a baseline. The target taxa show the expected shift in isotope ratios of δ15N with trophic level, from plants to cursorial spiders to web-builders to spider eaters. Remarkably, organisms at all trophic levels also precisely reflect the successional changes in the soil stoichiometry of the island chronosequence, demonstrating how the biogeochemistry of the entire food web is determined by ecosystem succession of the substrates on which the organisms have evolved. PMID:29576984

A Markovian Approach Applied to Reliability Modeling of Bidirectional DC-DC Converters Used in PHEVs and Smart Grids

Directory of Open Access Journals (Sweden)

M. Khalilzadeh

2016-12-01

Full Text Available In this paper, a stochastic approach is proposed for reliability assessment of bidirectional DC-DC converters, including the fault-tolerant ones. This type of converters can be used in a smart DC grid, feeding DC loads such as home appliances and plug-in hybrid electric vehicles (PHEVs. The reliability of bidirectional DC-DC converters is of such an importance, due to the key role of the expected increasingly utilization of DC grids in modern Smart Grid. Markov processes are suggested for reliability modeling and consequently calculating the expected effective lifetime of bidirectional converters. A three-leg bidirectional interleaved converter using data of Toyota Prius 2012 hybrid electric vehicle is used as a case study. Besides, the influence of environment and ambient temperature on converter lifetime is studied. The impact of modeling the reliability of the converter and adding reliability constraints on the technical design procedure of the converter is also investigated. In order to investigate the effect of leg increase on the lifetime of the converter, single leg to five-leg interleave DC-DC converters are studied considering economical aspect and the results are extrapolated for six and seven-leg converters. The proposed method could be generalized so that the number of legs and input and output capacitors could be an arbitrary number.

Automatic Detection of Cortical Arousals in Sleep using Bi-direction LSTM Networks

DEFF Research Database (Denmark)

Brink-Kjaer, A.; Olesen, Alexander Neergaard; Jespersen, C. A.

2018-01-01

) and chin electromyography (EMG) to compute a probability of arousals through a bi-directional long short-term memory neural network. The study used a dataset of 233 nocturnal PSGs of population-based samples from Wisconsin Sleep Cohort (WSC) and 30 nocturnal PSGs of clinical samples from the Stanford Sleep...

Bidirectional Associations Between Psychosocial Well-being and Body Mass Index in European Children

DEFF Research Database (Denmark)

Hunsberger, Monica; Lehtinen-Jacks, Susanna; Mehlig, Kirsten

2016-01-01

Background: The negative impact of childhood overweight on psychosocial well-being has been demonstrated in a number of studies. There is also evidence that psychosocial well-being may influence future overweight. We examined the bidirectional association between childhood overweight and psychoso...

Periodontal disease and non-communicable diseases. Strength of bidirectional associations

OpenAIRE

Kassier, SM

2016-01-01

Periodontal disease (PD), along with cardiovascular and circulatory disease, diabetes mellitus, chronic respiratory disease and obesity, are globally regarded as some of the major non-communicable diseases (NCDs). The association between PD and these systemic illnesses is described as bidirectional. Gaining an understanding of the strength of the proposed associations between these diseases is important, as it will enable health professionals to identify common risk factors that will allow fo...

Bidirectional Cardio-Respiratory Interactions in Heart Failure

Directory of Open Access Journals (Sweden)

Nikola N. Radovanović

2018-03-01

Full Text Available We investigated cardio-respiratory coupling in patients with heart failure by quantification of bidirectional interactions between cardiac (RR intervals and respiratory signals with complementary measures of time series analysis. Heart failure patients were divided into three groups of twenty, age and gender matched, subjects: with sinus rhythm (HF-Sin, with sinus rhythm and ventricular extrasystoles (HF-VES, and with permanent atrial fibrillation (HF-AF. We included patients with indication for implantation of implantable cardioverter defibrillator or cardiac resynchronization therapy device. ECG and respiratory signals were simultaneously acquired during 20 min in supine position at spontaneous breathing frequency in 20 healthy control subjects and in patients before device implantation. We used coherence, Granger causality and cross-sample entropy analysis as complementary measures of bidirectional interactions between RR intervals and respiratory rhythm. In heart failure patients with arrhythmias (HF-VES and HF-AF there is no coherence between signals (p < 0.01, while in HF-Sin it is reduced (p < 0.05, compared with control subjects. In all heart failure groups causality between signals is diminished, but with significantly stronger causality of RR signal in respiratory signal in HF-VES. Cross-sample entropy analysis revealed the strongest synchrony between respiratory and RR signal in HF-VES group. Beside respiratory sinus arrhythmia there is another type of cardio-respiratory interaction based on the synchrony between cardiac and respiratory rhythm. Both of them are altered in heart failure patients. Respiratory sinus arrhythmia is reduced in HF-Sin patients and vanished in heart failure patients with arrhythmias. Contrary, in HF-Sin and HF-VES groups, synchrony increased, probably as consequence of some dominant neural compensatory mechanisms. The coupling of cardiac and respiratory rhythm in heart failure patients varies depending on the

BiPOD Arthroscopic Acromioclavicular Repair Restores Bidirectional Stability.

Science.gov (United States)

De Beer, Joe; Schaer, Michael; Latendresse, Kim; Raniga, Sumit; Moor, Beat K; Zumstein, Matthias A

2017-01-01

Stabilizing the acromioclavicular joint in the vertical and horizontal planes is challenging, and most current techniques do not reliably achieve this goal. The BiPOD repair is an arthroscopically assisted procedure performed with image intensifier guidance that reconstructs the coracoclavicular ligaments as well as the acromioclavicular ligaments to achieve bidirectional stability. Repair is achieved with a combination of 2-mm FiberTape (Arthrex, Naples, Florida) and 20-mm Poly-Tape (Neoligaments, Leeds, England) to achieve rigid repair, prevent bone abrasion, and promote tissue ingrowth. This study is a prospective review of the first 6 patients treated for high-grade acute acromioclavicular injury with the BiPOD technique. The study included 6 men who were 21 to 36 years old (mean, 27 years). At 6-month follow-up, complications were recorded and radiographic analysis was used to determine the coracoclavicular distance for vertical reduction and the amount of acromioclavicular translation on the Alexander axillary view was used to determine horizontal reduction. One patient had a superficial infection over the tape knot. The difference in coracoclavicular distance between the operated side and the uninvolved side was 9±2 mm preoperatively and 0.3±2 mm at 6-month follow-up. On Alexander axillary view, all 6 patients showed stable reduction, which is defined as a clavicle that is in line with the acromion. The findings show that BiPOD acromioclavicular reconstruction restores bidirectional stability of the acromioclavicular joint at 6 months. [Orthopedics. 2017; 40(1):e35-e43.]. Copyright 2016, SLACK Incorporated.

Bi-directional charger for swiss2G - Annual report; Bi-directional charger for swiss2G - Jahresbericht

Energy Technology Data Exchange (ETDEWEB)

Schwab, M.; Baumann, P.

2010-11-15

This short annual report for 2010 for the Swiss Federal Office of Energy (SFOE) takes a look at a bi-directional charger that can be used in intelligent 'Smart Grid' applications. The idea is based on being able to use electric vehicles as a source of electricity to help meet peak demand for mains electricity. The swiss2G project aims to produce an electric car battery-charger that also functions as an inverter to convert the car's DC battery voltage to mains electricity. The project was started in September 2010. The report describes the aims of the project and reports on initial work done in the areas of safety, switching electronics and AC/DC conversion. National and international co-operation is noted and prospects for further work are discussed.

Hyperspectral Vehicle BRDF Learning: An Exploration of Vehicle Reflectance Variation and Optimal Measures of Spectral Similarity for Vehicle Reacquisition and Tracking Algorithms

Science.gov (United States)

Svejkosky, Joseph

The spectral signatures of vehicles in hyperspectral imagery exhibit temporal variations due to the preponderance of surfaces with material properties that display non-Lambertian bi-directional reflectance distribution functions (BRDFs). These temporal variations are caused by changing illumination conditions, changing sun-target-sensor geometry, changing road surface properties, and changing vehicle orientations. To quantify these variations and determine their relative importance in a sub-pixel vehicle reacquisition and tracking scenario, a hyperspectral vehicle BRDF sampling experiment was conducted in which four vehicles were rotated at different orientations and imaged over a six-hour period. The hyperspectral imagery was calibrated using novel in-scene methods and converted to reflectance imagery. The resulting BRDF sampled time-series imagery showed a strong vehicle level BRDF dependence on vehicle shape in off-nadir imaging scenarios and a strong dependence on vehicle color in simulated nadir imaging scenarios. The imagery also exhibited spectral features characteristic of sampling the BRDF of non-Lambertian targets, which were subsequently verified with simulations. In addition, the imagery demonstrated that the illumination contribution from vehicle adjacent horizontal surfaces significantly altered the shape and magnitude of the vehicle reflectance spectrum. The results of the BRDF sampling experiment illustrate the need for a target vehicle BRDF model and detection scheme that incorporates non-Lambertian BRDFs. A new detection algorithm called Eigenvector Loading Regression (ELR) is proposed that learns a hyperspectral vehicle BRDF from a series of BRDF measurements using regression in a lower dimensional space and then applies the learned BRDF to make test spectrum predictions. In cases of non-Lambertian vehicle BRDF, this detection methodology performs favorably when compared to subspace detections algorithms and graph-based detection algorithms that

Thermoluminescence, infrared reflectivity and electron paramagnetic resonance properties of hemimorphite

Energy Technology Data Exchange (ETDEWEB)

Gallegos, E.A. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo, SP (Brazil); Cano, N.F. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo, SP (Brazil)], E-mail: nilocano@dfn.if.usp.br; Watanabe, S.; Chubaci, J.F.D. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo, SP (Brazil)

2009-01-15

Silicate mineral hemimorphite has been investigated concerning its TL, IR and EPR properties. A broad TL peak around 180 deg. C and a weaker and narrower peak around 360 deg. C were found in a sample annealed at 600 deg. C for 1 h and then irradiated. The deconvolution using the CGCD method revealed peaks around 132, 169, 222 and 367 deg. C. The reflectivity measurements showed several bands in the NIR region due to H{sub 2}O, OH and Al-OH complexes. No band was observed in the visible region. The thermal treatments were carried out from {approx}110 to 940 deg. C and dehydration was observed, first causing a diminishing optical absorption in general and the disappearance of water and hydroxyl absorption bands. The EPR spectrum of natural hemimorphite, presented Cu{sup 2+} signals at g = 2.4 and g = 2.1 plus E{sub 1}' signal superposed to Fe{sup 3+} signal around g = 2.0.

Wavelet-Based Modelling of Spectral BRDF Data

OpenAIRE

Claustres , Luc; Boucher , Yannick; Paulin , Mathias

2004-01-01

International audience; The Bidirectional Reflectance Distribution Function (BRDF) is an important surface property, and is commonly used to describe reflected light patterns. However, the BRDF is a complex function since it has four angular degrees of freedom and also depends on the wavelength. The direct use of BRDF data set may be inefficient for scene modelling algorithms for example. Thus, models provide compression and additional functionalities like interpolation. One common way consis...

Modeling the effect of reflection from metallic walls on spectroscopic measurements

International Nuclear Information System (INIS)

Zastrow, K.-D.; Keatings, S. R.; O'Mullane, M. G.; Marot, L.; Temmerman, G. de

2008-01-01

A modification of JET is presently being prepared to bring operational experience with ITER-like first wall (Be) and divertor (W) materials, geometry and plasma parameters. Reflectivity measurements of JET sample tiles have been performed and the data are used within a simplified model of the JET and ITER vessels to predict additional contributions to quantitative spectroscopic measurements. The most general method to characterize reflectivity is the bidirectional reflection distribution function (BRDF). For extended sources however, such as bremsstrahlung and edge emission of fuel and intrinsic impurities, the results obtained in the modeling are almost as accurate if the total reflectivity with ideal Lambertian angular dependence is used. This is in contrast to the experience in other communities, such as optical design, lighting design, or rendering who deal mostly with pointlike light sources. This result is so far based on a very limited set of measurements and will be reassessed when more detailed BRDF measurements of JET tiles have been made. If it is true it offers the possibility of in situ monitoring of the reflectivity of selected parts of the wall during exposure to plasma operation, while remeasurement of the BRDF is performed during interventions. For a closed vessel structure such as ITER, it is important to consider multiple reflections. This makes it more important to represent the whole of the vessel reasonably accurately in the model, which on the other hand is easier to achieve than for the more complex internal structure of JET. In both cases the dominant contribution is from the first reflection, and a detailed model of the areas intersected by lines of sight of diagnostic interest is required.

Bi-Directional DC-DC Converter for PHEV Applications

Energy Technology Data Exchange (ETDEWEB)

Abas Goodarzi

2011-01-31

Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

A Long Look at MCG-5-23-16 with NuSTAR . I. Relativistic Reflection and Coronal Properties

Energy Technology Data Exchange (ETDEWEB)

Zoghbi, Abderahmen; Miller, J. M. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Lohfink, A. M. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom); Walton, D. J.; Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Ballantyne, D. R. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); García, J. A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Koss, M. J. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Harrison, F. A. [Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Boggs, S. E.; Craig, W. [Space Science Laboratory, University of California, Berkeley, California 94720 (United States); Christensen, F. E. [DTU Space. National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027 (United States); Zhang, W. W., E-mail: abzoghbi@umich.edu [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)

2017-02-10

MCG-5-23-16 was targeted in early 2015 with a half mega-second observing campaign using NuSTAR . Here we present the spectral analysis of these data sets along with an earlier observation and study the relativistic reflection and the primary coronal source. The data show strong reflection features in the form of both narrow and broad iron lines plus a Compton reflection hump. A cutoff energy is significantly detected in all exposures. The shape of the reflection spectrum does not change in the two years spanned by the observations, suggesting a stable geometry. A strong positive correlation is found between the cutoff energy and both the hard X-ray flux and spectral index. The measurements imply that the coronal plasma is not at the runaway electron–positron pair limit, and instead contains mostly electrons. The observed variability in the coronal properties is driven by a variable optical depth. A constant heating-to-cooling ratio is measured, implying that there is a feedback mechanism in which a significant fraction of the photons cooling the corona are due to reprocessed hard X-rays.

A Long Look at MCG-5-23-16 with NuSTAR. I. Relativistic Reflection and Coronal Properties

Science.gov (United States)

Zoghbi, Abderahmen; Matt, G.; Miller, J. M.; Lohfink, A. M.; Walton, D. J.; Ballantyne, D. R.; Garcia, J. A.; Stern, D.; Koss, M. J.; Farrah, D.;

Poor School Bonding and Delinquency over Time: Bidirectional Effects and Sex Differences

Science.gov (United States)

Liljeberg, Jenny Freidenfelt; Eklund, Jenny M.; Fritz, Marie Vafors; Klinteberg, Britt af

2011-01-01

The association between poor school bonding and delinquency has only been partly addressed in earlier research. Using a longitudinal design, the objective of our study was to investigate possible bidirectional effects and sex differences between adolescents' experienced school bonding and self-rated delinquency over time. A total of 788…

DEVELOPMENT AND DEMONSTRATION OF A BIDIRECTIONAL ADVECTIVE FLUX METER FOR SEDIMENT-WATER INTERFACE

Science.gov (United States)

A bidirectional advective flux meter for measuring water transport across the sediment-water interface has been successfully developed and field tested. The flow sensor employs a heat-pulse technique combined with a flow collection funnel for the flow measurement. Because the dir...

SiC-based High Efficiency Bidirectional Battery Converter for Smart PV Residential Systems

DEFF Research Database (Denmark)

Pham, Cam; Biris, Valeriu-Ciprian; Teodorescu, Remus

2013-01-01

Smart PV inverters are essential components of future grids. Beside conventional functionalities they can communicate with the grid, supports the grid with reactive power and with active power from internal battery storage. To maximize internal consumption, a high efficiency bidirectional DC-DC c...

Three-port bidirectional converter for electric vehicles : focus on high-frequency coaxial transformer

NARCIS (Netherlands)

Waltrich, G.; Duarte, J.L.; Hendrix, M.A.M.; Paulides, J.J.H.

2010-01-01

A bi-directional multi-port converter can accommodate various energy storages and sources. Therefore, a multiport converter will be a good candidate for application as a future universal converter for (hybrid) electrical vehicles or local distribution systems. The main design challenge of the

Bidirectional Text Messaging to Improve Adherence to Recommended Lipid Testing.

Science.gov (United States)

Baldwin, Laura-Mae; Morrison, Caitlin; Griffin, Jonathan; Anderson, Nick; Edwards, Kelly; Green, Jeff; Waldren, Cleary; Reiter, William

2017-01-01

Synergies between technology and health care in the United States are accelerating, increasing opportunities to leverage these technologies to improve patient care. This study was a collaboration between an academic study team, a rural primary care clinic, and a local nonprofit informatics company developing tools to improve patient care through population management. Our team created a text messaging management tool, then developed methods for and tested the feasibility of bidirectional text messaging to remind eligible patients about the need for lipid testing. We measured patient response to the text messages, then interviewed 8 patients to explore their text messaging experience. Of the 129 patients the clinic was able to contact by phone, 29.4% had no cell phone or text-messaging capabilities. An additional 20% refused to participate. Two thirds of the 28 patients who participated in the text messaging intervention (67.9%) responded to at least 1 of the up to 3 messages. Seven of 8 interviewed patients had a positive text-messaging experience. Bidirectional text messaging is a feasible and largely acceptable form of communication for test reminders that has the potential to reach large numbers of patients in clinical care. © Copyright 2017 by the American Board of Family Medicine.

Bidirectional modulation of goal-directed actions by prefrontal cortical dopamine.

Science.gov (United States)

Hitchcott, Paul K; Quinn, Jennifer J; Taylor, Jane R

2007-12-01

Instrumental actions are a vital cognitive asset that endows an organism with sensitivity to the consequences of its behavior. Response-outcome feedback allows responding to be shaped in order to maximize beneficial, and minimize detrimental, outcomes. Lesions of the medial prefrontal cortex (mPFC) result in behavior that is insensitive to changes in outcome value in animals and compulsive behavior in several human psychopathologies. Such insensitivity to changes in outcome value is a defining characteristic of instrumental habits: responses that are controlled by antecedent stimuli rather than goal expectancy. Little is known regarding the neurochemical substrates mediating this sensitivity. The present experiments used sensitivity to posttraining outcome devaluation to index the action-habit status of instrumental responding. Infusions of dopamine into the ventral mPFC (vmPFC), but not dorsal mPFC, restored outcome sensitivity bidirectionally-decreasing responding following outcome devaluation and increasing responding when the outcome was not devalued. This bidirectionality makes the possibility that these infusions nonspecifically dysregulated vmPFC dopamine transmission unlikely. VmPFC dopamine promoted instrumental responding appropriate to outcome value. Reinforcer consumption data indicated that this was not a consequence of altered sensitivity to the reinforcer itself. We suggest that vmPFC dopamine reengages attentional processes underlying goal-directed behavior.

Effect of titanium dioxide (TiO2) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

International Nuclear Information System (INIS)

Wang, Shichao; Zhang, Jun

2014-01-01

Highlights: • HDPE/TiO 2 composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO 2 composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO 2 ) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO 2 particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO 2 particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO 2 particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO 2 particles in HDPE matrix. It was found the rutile TiO 2 could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result

The Effects of Framing, Reflection, Probability, and Payoff on Risk Preference in Choice Tasks.

Science.gov (United States)

Kühberger; Schulte-Mecklenbeck; Perner

1999-06-01

A meta-analysis of Asian-disease-like studies is presented to identify the factors which determine risk preference. First the confoundings between probability levels, payoffs, and framing conditions are clarified in a task analysis. Then the role of framing, reflection, probability, type, and size of payoff is evaluated in a meta-analysis. It is shown that bidirectional framing effects exist for gains and for losses. Presenting outcomes as gains tends to induce risk aversion, while presenting outcomes as losses tends to induce risk seeking. Risk preference is also shown to depend on the size of the payoffs, on the probability levels, and on the type of good at stake (money/property vs human lives). In general, higher payoffs lead to increasing risk aversion. Higher probabilities lead to increasing risk aversion for gains and to increasing risk seeking for losses. These findings are confirmed by a subsequent empirical test. Shortcomings of existing formal theories, such as prospect theory, cumulative prospect theory, venture theory, and Markowitz's utility theory, are identified. It is shown that it is not probabilities or payoffs, but the framing condition, which explains most variance. These findings are interpreted as showing that no linear combination of formally relevant predictors is sufficient to capture the essence of the framing phenomenon. Copyright 1999 Academic Press.

Periodic bidirectional associative memory neural networks with distributed delays

Science.gov (United States)

Chen, Anping; Huang, Lihong; Liu, Zhigang; Cao, Jinde

2006-05-01

Some sufficient conditions are obtained for the existence and global exponential stability of a periodic solution to the general bidirectional associative memory (BAM) neural networks with distributed delays by using the continuation theorem of Mawhin's coincidence degree theory and the Lyapunov functional method and the Young's inequality technique. These results are helpful for designing a globally exponentially stable and periodic oscillatory BAM neural network, and the conditions can be easily verified and be applied in practice. An example is also given to illustrate our results.

Bidirectional Texture Function Compression Based on Multi-Level Vector Quantization

Czech Academy of Sciences Publication Activity Database

Havran, V.; Filip, Jiří; Myszkowski, K.

2010-01-01

Roč. 29, č. 1 (2010), s. 175-190 ISSN 0167-7055 R&D Projects: GA MŠk 1M0572; GA ČR GA102/08/0593 Grant - others:EC Marie Curie ERG(CZ) 239294 Institutional research plan: CEZ:AV0Z10750506 Keywords : bidirectional texture function * BRDF * compression * SSIM Subject RIV: BD - Theory of Information Impact factor: 1.455, year: 2010 http://library.utia.cas.cz/separaty/2010/RO/filip-0338804.pdf

UV reflection properties of plumage and skin of domesticated turkeys (Meleagris gallopavo f. dom.) as revealed by UV photography.

Science.gov (United States)

Bartels, T; Lütgeharm, J-H; Wähner, M; Berk, J

2017-12-01

Reflection and fluorescence properties of feathered and non-feathered body regions of white- and bronze-colored fattening turkeys of various ages were examined by ultraviolet (UV) photography. The examinations were carried out on 20 white-feathered fattening turkeys (B.U.T. 6; 10 males, 10 females) and 20 bronze-feathered fattening turkeys (Grelier 708; 10 males, 10 females) over a period of 21 weeks. The turkeys were photographed once a wk under long-wave UV (UVA) radiation illumination (λ = 344-407 nm) using a digital camera. A bandpass filter was used for UV reflectography to filter out the visible components of the used light source. A longpass filter was used for UV fluorescence photography to avoid blurring in the image due to chromatic aberration as a result of UV illumination. We found that natal down feathers of white-feathered turkeys showed an intense yellowish-green fluorescence under UVA light. UVA fluorescence also was shown by the natal downs of the slightly melanized plumage areas of bronze turkeys. Vaned feathers of white fattening turkeys reflected UVA radiation. Freshly molted feathers were optically distinguishable from the previous feather generation due to their more intense UVA reflection. In bronze turkeys, both the bright end seams of the dark pennaceous feathers and rectrices and the bright banding of primary and secondary remiges reflected UVA radiation. Intense UVA fluorescence was recognizable in day-old chicks of both color variants on the scutellate scales of the legs and toes. In male turkeys of both color variants, UVA-reflecting parts were recognizable with increasing age on the featherless head region. The UVA-fluorescent and UVA-reflective characteristics of the plumage of fattening turkeys were closely related to the plumage color, the feather type, the molting state, and the age of the birds. Further research is needed regarding the UVA-reflecting properties of the turkey plumage and the effects of full-spectrum illumination

Bidirectional 3.125 Gbps downstream / 2 Gbps upstream impulse radio ultrawide-band (UWB) over combined fiber and wireless link

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee; Gibbon, Timothy Braidwood; Yu, Xianbin

2010-01-01

We demonstrate bidirectional fiber and wireless transmission of impulse radio ultra-wideband at 3.125 Gbps downstream and 2 Gbps upstream. After transmission over 50 km fiber and 1.85 m wireless link both signals are recovered without errors.......We demonstrate bidirectional fiber and wireless transmission of impulse radio ultra-wideband at 3.125 Gbps downstream and 2 Gbps upstream. After transmission over 50 km fiber and 1.85 m wireless link both signals are recovered without errors....

Bidirectional Associations Between Newlyweds' Marital Satisfaction and Marital Problems over Time.

Science.gov (United States)

Lavner, Justin A; Karney, Benjamin R; Williamson, Hannah C; Bradbury, Thomas N

2017-12-01

Prevailing views of marital functioning generally adopt the view that marital problems predict decreases in marital satisfaction, but alternative theoretical perspectives raise the possibility that lowered satisfaction can also predict increases in problems. The current study sought to integrate and compare these perspectives by examining the bidirectional cross-lagged associations between newlyweds' reports of their marital satisfaction and marital problems over the first 4 years of marriage. Using annual assessments from 483 heterosexual newlywed couples, we find evidence for problem-to-satisfaction linkages as well as satisfaction-to-problem linkages. Satisfaction was a stronger predictor of marital problems early in marriage but not as time passed; by Year 4 only problem-to-satisfaction linkages remained significant. These findings are consistent with the idea that couples with more problems go on to report lower levels of satisfaction and couples with lower levels of satisfaction go on to report more marital problems. This dynamic interplay between global judgments about relationship satisfaction and ongoing specific relationship difficulties highlights the value of examining bidirectional effects to better understand marital functioning over time. © 2016 Family Process Institute.

Selectively reflective transparent sheets

Science.gov (United States)

Waché, Rémi; Florescu, Marian; Sweeney, Stephen J.; Clowes, Steven K.

2015-08-01

We investigate the possibility to selectively reflect certain wavelengths while maintaining the optical properties on other spectral ranges. This is of particular interest for transparent materials, which for specific applications may require high reflectivity at pre-determined frequencies. Although there exist currently techniques such as coatings to produce selective reflection, this work focuses on new approaches for mass production of polyethylene sheets which incorporate either additives or surface patterning for selective reflection between 8 to 13 μ m. Typical additives used to produce a greenhouse effect in plastics include particles such as clays, silica or hydroxide materials. However, the absorption of thermal radiation is less efficient than the decrease of emissivity as it can be compared with the inclusion of Lambertian materials. Photonic band gap engineering by the periodic structuring of metamaterials is known in nature for producing the vivid bright colors in certain organisms via strong wavelength-selective reflection. Research to artificially engineer such structures has mainly focused on wavelengths in the visible and near infrared. However few studies to date have been carried out to investigate the properties of metastructures in the mid infrared range even though the patterning of microstructure is easier to achieve. We present preliminary results on the diffuse reflectivity using FDTD simulations and analyze the technical feasibility of these approaches.

Adjustment of Sentinel-2 Multi-Spectral Instrument (MSI Red-Edge Band Reflectance to Nadir BRDF Adjusted Reflectance (NBAR and Quantification of Red-Edge Band BRDF Effects

Directory of Open Access Journals (Sweden)

David P. Roy

2017-12-01

Full Text Available Optical wavelength satellite data have directional reflectance effects over non-Lambertian surfaces, described by the bidirectional reflectance distribution function (BRDF. The Sentinel-2 multi-spectral instrument (MSI acquires data over a 20.6° field of view that have been shown to have non-negligible BRDF effects in the visible, near-infrared, and short wave infrared bands. MSI red-edge BRDF effects have not been investigated. In this study, they are quantified by an examination of 6.6 million (January 2016 and 10.7 million (April 2016 pairs of forward and back scatter reflectance observations extracted over approximately 20° × 10° of southern Africa. Non-negligible MSI red-edge BRDF effects up to 0.08 (reflectance units across the 290 km wide MSI swath are documented. A recently published MODIS BRDF parameter c-factor approach to adjust MSI visible, near-infrared, and short wave infrared reflectance to nadir BRDF-adjusted reflectance (NBAR is adapted for application to the MSI red-edge bands. The red-edge band BRDF parameters needed to implement the algorithm are provided. The parameters are derived by a linear wavelength interpolation of fixed global MODIS red and NIR BRDF model parameters. The efficacy of the interpolation is investigated using POLDER red, red-edge, and NIR BRDF model parameters, and is shown to be appropriate for the c-factor NBAR generation approach. After adjustment to NBAR, red-edge MSI BRDF effects were reduced for the January data (acquired close to the solar principal where BRDF effects are maximal and the April data (acquired close to the orthogonal plane for all the MSI red-edge bands.

Bidirectional modulation of taste aversion extinction by insular cortex LTP and LTD.

Science.gov (United States)

Rodríguez-Durán, Luis F; Martínez-Moreno, Araceli; Escobar, Martha L

2017-07-01

The history of activity of a given neuron has been proposed to bidirectionally influence its future response to synaptic inputs. In particular, induction of synaptic plasticity expressions such as long-term potentiation (LTP) and long-term depression (LTD) modifies the performance of several behavioral tasks. Our previous studies in the insular cortex (IC), a neocortical region that has been related to acquisition and retention of conditioned taste aversion (CTA), have demonstrated that induction of LTP in the basolateral amygdaloid nucleus (Bla)-IC pathway before CTA training enhances the retention of this task. In addition, we reported that CTA training triggers a persistent impairment in the ability to induce in vivo LTP in the IC. The aim of the present study was to investigate whether LTD can be induced in the Bla-IC projection in vivo, as well as, whether the extinction of CTA is bidirectionally modified by previous synaptic plasticity induction in this pathway. Thus, rats received 900 train pulses (five 250μs pulses at 250Hz) delivered at 1Hz in the Bla-IC projection in order to induce LTD or 10 trains of 100Hz/1s with an intertrain interval of 20s in order to induce LTP. Seven days after surgery, rats were trained in the CTA task including the extinction trials. Our results show that the Bla-IC pathway is able to express in vivo LTD in an N-Methyl-D-aspartate (NMDA) receptor-dependent manner. Induction of LTD in the Bla-IC projection previous to CTA training facilitates the extinction of this task. Conversely, LTP induction enhances CTA retention. The present results show the bidirectional modulation of CTA extinction in response to IC-LTP and LTD, providing evidence of the homeostatic adaptation of taste learning. Copyright © 2016 Elsevier Inc. All rights reserved.

Optimal Design of a Push-Pull-Forward Half-Bridge (PPFHB) Bidirectional DC–DC Converter With Variable Input Voltage

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2012-01-01

This paper presents a low-cost bidirectional isolated dc–dc converte, derived from dual-active-bridge converter for the power sources with variable output voltage like supercapacitors. The proposed converter consists of push-pull-forward circuit half-bridge circuit (PPFHB) and a high-frequency tr......This paper presents a low-cost bidirectional isolated dc–dc converte, derived from dual-active-bridge converter for the power sources with variable output voltage like supercapacitors. The proposed converter consists of push-pull-forward circuit half-bridge circuit (PPFHB) and a high...

Bidirectional Associations between Parenting Practices and Conduct Problems in Boys from Childhood to Adolescence: The Moderating Effect of Age and African-American Ethnicity

Science.gov (United States)

Pardini, Dustin A.; Fite, Paula J.; Burke, Jeffrey D.

2008-01-01

This study examined the bidirectional relationship between parent and teacher reported conduct problems in youth and parenting practices using a longitudinal sample of boys assessed from 6 to 16 years of age. Analyses tested whether these bidirectional associations changed across development and whether the nature of these associations varied…

Dynamic analysis of stochastic bidirectional associative memory neural networks with delays

International Nuclear Information System (INIS)

Zhao Hongyong; Ding Nan

2007-01-01

In this paper, stochastic bidirectional associative memory neural networks model with delays is considered. By constructing Lyapunov functionals, and using stochastic analysis method and inequality technique, we give some sufficient criteria ensuring almost sure exponential stability, pth exponential stability and mean value exponential stability. The obtained criteria can be used as theoretic guidance to stabilize neural networks in practical applications when stochastic noise is taken into consideration

Optimization of Bi-Directional Flyback Converter for a High Voltage Capacitor Charging Application

DEFF Research Database (Denmark)

Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe

2014-01-01

This paper presents an optimization technique for a flyback converter with a bidirectional energy transfer. The main goal is to optimize the converter for driving an incremental dielectric electro active polymer actuator, which must be charged and discharged from 0 V to 2500 V DC, supplied from...

Finite-Time Stability for Fractional-Order Bidirectional Associative Memory Neural Networks with Time Delays

Science.gov (United States)

Xu, Chang-Jin; Li, Pei-Luan; Pang, Yi-Cheng

2017-02-01

This paper is concerned with fractional-order bidirectional associative memory (BAM) neural networks with time delays. Applying Laplace transform, the generalized Gronwall inequality and estimates of Mittag-Leffler functions, some sufficient conditions which ensure the finite-time stability of fractional-order bidirectional associative memory neural networks with time delays are obtained. Two examples with their simulations are given to illustrate the theoretical findings. Our results are new and complement previously known results. Supported by National Natural Science Foundation of China under Grant Nos.~61673008, 11261010, 11101126, Project of High-Level Innovative Talents of Guizhou Province ([2016]5651), Natural Science and Technology Foundation of Guizhou Province (J[2015]2025 and J[2015]2026), 125 Special Major Science and Technology of Department of Education of Guizhou Province ([2012]011) and Natural Science Foundation of the Education Department of Guizhou Province (KY[2015]482)

Bidirectional Texture Function Modeling: State of the Art Survey

Czech Academy of Sciences Publication Activity Database

Filip, Jiří; Haindl, Michal

2009-01-01

Roč. 31, č. 11 (2009), s. 1921-1940 ISSN 0162-8828 R&D Projects: GA MŠk 1M0572; GA ČR GA102/08/0593; GA AV ČR 1ET400750407 Grant - others:EC Marie Curie(BE) 41358; GA MŠk(CZ) 2C06019 Institutional research plan: CEZ:AV0Z10750506 Keywords : BTF * surface texture * 3D texture Subject RIV: BD - Theory of Information Impact factor: 4.378, year: 2009 http://library.utia.cas.cz/separaty/2009/RO/filip-bidirectional texture function modeling state of the art survey.pdf

Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface

International Nuclear Information System (INIS)

Adib, Ehsan; Farzanehfard, Hosein

2009-01-01

In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis.

Bi-directional LSTM Recurrent Neural Network for Chinese Word Segmentation

OpenAIRE

Yao, Yushi; Huang, Zheng

2016-01-01

Recurrent neural network(RNN) has been broadly applied to natural language processing(NLP) problems. This kind of neural network is designed for modeling sequential data and has been testified to be quite efficient in sequential tagging tasks. In this paper, we propose to use bi-directional RNN with long short-term memory(LSTM) units for Chinese word segmentation, which is a crucial preprocess task for modeling Chinese sentences and articles. Classical methods focus on designing and combining...

Bidirectional Relations between Temperament and Parenting Styles in Chinese Children

OpenAIRE

Lee, Erica H.; Zhou, Qing; Eisenberg, Nancy; Wang, Yun

2012-01-01

The present study examined bidirectional relations between child temperament and parenting styles in a sample (n = 425) of Chinese children during elementary school period (age range = 6 to 9 years at Wave 1). Using two waves (3.8 years apart) of longitudinal data, we tested two hypotheses: (1) whether child temperament (effortful control and anger/frustration) at Wave 1 predicts parenting styles (authoritative and authoritarian parenting) at Wave 2, controlling for Wave 1 parenting; and (2) ...

Wall reflection modeling for charge exchange recombination spectroscopy (CXRS) measurements on Textor and ITER

International Nuclear Information System (INIS)

Banerjee, Santanu; Vasu, P; Von Hellermann, M; Jaspers, R J E

2010-01-01

Contamination of optical signals by reflections from the tokamak vessel wall is a matter of great concern. For machines such as ITER and future reactors, where the vessel wall will be predominantly metallic, this is potentially a risk factor for quantitative optical emission spectroscopy. This is, in particular, the case when bremsstrahlung continuum radiation from the bulk plasma is used as a common reference light source for the cross-calibration of visible spectroscopy. In this paper the reflected contribution to the continuum level in Textor and ITER has been estimated for the detection channels meant for charge exchange recombination spectroscopy (CXRS). A model assuming diffuse reflection has been developed for the bremsstrahlung which is a much extended source. Based on this model, it is shown that in the case of ITER upper port 3, a wall with a moderate reflectivity of 20% leads to the wall reflected fraction being as high as 55-60% of the weak signals in the edge channels. In contrast, a complete bidirectional reflectance distribution function (BRDF) based model has been developed in order to estimate the reflections from more localized sources like the charge exchange (CX) emission from a neutral beam in tokamaks. The largest signal contamination of ∼15% is seen in the core CX channels, where the true CX signal level is much lower than that in the edge channels. Similar values are obtained for Textor also. These results indicate that the contributions from wall reflections may be large enough to significantly distort the overall spectral features of CX data, warranting an analysis at different wavelengths.

Wall reflection modeling for charge exchange recombination spectroscopy (CXRS) measurements on Textor and ITER

Energy Technology Data Exchange (ETDEWEB)

Banerjee, Santanu; Vasu, P [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India); Von Hellermann, M [FOM Institute for Plasma Physics, Rijnhuizen (Netherlands); Jaspers, R J E, E-mail: sbanerje@ipr.res.i [Applied Physics Department, Eindhoven University of Technology, Eindhoven (Netherlands)

2010-12-15

Contamination of optical signals by reflections from the tokamak vessel wall is a matter of great concern. For machines such as ITER and future reactors, where the vessel wall will be predominantly metallic, this is potentially a risk factor for quantitative optical emission spectroscopy. This is, in particular, the case when bremsstrahlung continuum radiation from the bulk plasma is used as a common reference light source for the cross-calibration of visible spectroscopy. In this paper the reflected contribution to the continuum level in Textor and ITER has been estimated for the detection channels meant for charge exchange recombination spectroscopy (CXRS). A model assuming diffuse reflection has been developed for the bremsstrahlung which is a much extended source. Based on this model, it is shown that in the case of ITER upper port 3, a wall with a moderate reflectivity of 20% leads to the wall reflected fraction being as high as 55-60% of the weak signals in the edge channels. In contrast, a complete bidirectional reflectance distribution function (BRDF) based model has been developed in order to estimate the reflections from more localized sources like the charge exchange (CX) emission from a neutral beam in tokamaks. The largest signal contamination of {approx}15% is seen in the core CX channels, where the true CX signal level is much lower than that in the edge channels. Similar values are obtained for Textor also. These results indicate that the contributions from wall reflections may be large enough to significantly distort the overall spectral features of CX data, warranting an analysis at different wavelengths.

Ocean color remote sensing using polarization properties of reflected sunlight

Science.gov (United States)

Frouin, R.; Pouliquen, E.; Breon, F.-M.

1994-01-01

The effects of the atmosphere and surface on sunlight backscattered to space by the ocean may be substantially reduced by using the unpolarized component of reflectance instead of total reflectance. At 450 nm, a wavelength of interest in ocean color remote sensing, and for typical conditions, 45% of the unpolarized reflectance may originate from the water body instead of 20% of the total reflectance, which represents a gain of a factor 2.2 in useful signal for water composition retrieval. The best viewing geometries are adjacent to the glitter region; they correspond to scattering angles around 100 deg, but they may change slightly depending on the polarization characteristics of the aerosols. As aerosol optical thickness increases, the atmosphere becomes less efficient at polarizing sunlight, and the enhancement of the water body contribution to unpolarized reflectance is reduced. Since the perturbing effects are smaller on unpolarized reflectance, at least for some viewing geometries, they may be more easily corrected, leading to a more accurate water-leaving signal and, therefore, more accurate estimates of phytoplankton pigment concentration.

Nitrogen vertical distribution by canopy reflectance spectrum in winter wheat

International Nuclear Information System (INIS)

Huang, W J; Yang, Q Y; Peng, D L; Huang, L S; Zhang, D Y; Yang, G J

2014-01-01

Nitrogen is a key factor for plant photosynthesis, ecosystem productivity and leaf respiration. Under the condition of nitrogen deficiency, the crop shows the nitrogen deficiency symptoms in the bottom leaves, while excessive nitrogen will affect the upper layer leaves first. Thus, timely measurement of vertical distribution of foliage nitrogen content is critical for growth diagnosis, crop management and reducing environmental impact. This study presents a method using bi-directional reflectance difference function (BRDF) data to invert foliage nitrogen vertical distribution. We developed upper-layer nitrogen inversion index (ULNI), middle-layer nitrogen inversion index (MLNI) and bottom-layer nitrogen inversion index (BLNI) to reflect foliage nitrogen inversion at upper layer, middle layer and bottom layer, respectively. Both ULNI and MLNI were made by the value of the ratio of Modified Chlorophyll Absorption Ration Index to the second Modified Triangular Vegetation Index (MCARI/MTVI2) referred to as canopy nitrogen inversion index (CNII) in this study at ±40° and ±50°, and at ±30° and ±40° view angles, respectively. The BLNI was composed by the value of nitrogen reflectance index (NRI) at ±20° and ±30° view angles. These results suggest that it is feasible to measure foliage nitrogen vertical-layer distribution in a large scale by remote sensing

Bi-directionally protective communication between neurons and astrocytes under ischemia.

Science.gov (United States)

Wu, Xiao-Mei; Qian, Christopher; Zhou, Yu-Fu; Yan, Yick-Chun; Luo, Qian-Qian; Yung, Wing-Ho; Zhang, Fa-Li; Jiang, Li-Rong; Qian, Zhong Ming; Ke, Ya

2017-10-01

The extensive existing knowledge on bi-directional communication between astrocytes and neurons led us to hypothesize that not only ischemia-preconditioned (IP) astrocytes can protect neurons but also IP neurons protect astrocytes from lethal ischemic injury. Here, we demonstrated for the first time that neurons have a significant role in protecting astrocytes from ischemic injury. The cultured medium from IP neurons (IPcNCM) induced a remarkable reduction in LDH and an increase in cell viability in ischemic astrocytes in vitro. Selective neuronal loss by kainic acid injection induced a significant increase in apoptotic astrocyte numbers in the brain of ischemic rats in vivo. Furthermore, TUNEL analysis, DNA ladder assay, and the measurements of ROS, GSH, pro- and anti-apoptotic factors, anti-oxidant enzymes and signal molecules in vitro and/or in vivo demonstrated that IP neurons protect astrocytes by an EPO-mediated inhibition of pro-apoptotic signals, activation of anti-apoptotic proteins via the P13K/ERK/STAT5 pathways and activation of anti-oxidant proteins via up-regulation of anti-oxidant enzymes. We demonstrated the existence of astro-protection by IP neurons under ischemia and proposed that the bi-directionally protective communications between cells might be a common activity in the brain or peripheral organs under most if not all pathological conditions. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Bi-directionally protective communication between neurons and astrocytes under ischemia

Directory of Open Access Journals (Sweden)

Xiao-Mei Wu

2017-10-01

Full Text Available The extensive existing knowledge on bi-directional communication between astrocytes and neurons led us to hypothesize that not only ischemia-preconditioned (IP astrocytes can protect neurons but also IP neurons protect astrocytes from lethal ischemic injury. Here, we demonstrated for the first time that neurons have a significant role in protecting astrocytes from ischemic injury. The cultured medium from IP neurons (IPcNCM induced a remarkable reduction in LDH and an increase in cell viability in ischemic astrocytes in vitro. Selective neuronal loss by kainic acid injection induced a significant increase in apoptotic astrocyte numbers in the brain of ischemic rats in vivo. Furthermore, TUNEL analysis, DNA ladder assay, and the measurements of ROS, GSH, pro- and anti-apoptotic factors, anti-oxidant enzymes and signal molecules in vitro and/or in vivo demonstrated that IP neurons protect astrocytes by an EPO-mediated inhibition of pro-apoptotic signals, activation of anti-apoptotic proteins via the P13K/ERK/STAT5 pathways and activation of anti-oxidant proteins via up-regulation of anti-oxidant enzymes. We demonstrated the existence of astro-protection by IP neurons under ischemia and proposed that the bi-directionally protective communications between cells might be a common activity in the brain or peripheral organs under most if not all pathological conditions.

The robustness in dynamics of out of equilibrium bidirectional transport systems with constrained entrances

Science.gov (United States)

Sharma, Natasha; Verma, Atul Kumar; Gupta, Arvind Kumar

2018-05-01

Macroscopic and microscopic long-distance bidirectional transfer depends on connections between entrances and exits of various transport mediums. Persuaded by the associations, we introduce a small system module of Totally Asymmetric Simple Exclusion Process including oppositely directed species of particles moving on two parallel channels with constrained entrances. The dynamical rules which characterize the system obey symmetry between the two species and are identical for both the channels. The model displays a rich steady-state behavior, including symmetry breaking phenomenon. The phase diagram is analyzed theoretically within the mean-field approximation and substantiated with Monte Carlo simulations. Relevant mean-field calculations are also presented. We further compared the phase segregation with those observed in previous works, and it is examined that the structure of phase separation in proposed model is distinguished from earlier ones. Interestingly, for phases with broken symmetry, symmetry with respect to channels has been observed as the distinct particles behave differently while the similar type of particles exhibits the same conduct in the system. For symmetric phases, significant properties including currents and densities in the channels are identical for both types of particles. The effect of symmetry breaking occurrence on the Monte Carlo simulation results has also been examined based on particle density histograms. Finally, phase properties of the system having strong size dependency have been explored based on simulations findings.

Simulation of an oil film at the sea surface and its radiometric properties in the SWIR

Science.gov (United States)

Schwenger, Frédéric; Van Eijk, Alexander M. J.

2017-10-01

The knowledge of the optical contrast of an oil layer on the sea under various surface roughness conditions is of great interest for oil slick monitoring techniques. This paper presents a 3D simulation of a dynamic sea surface contaminated by a floating oil film. The simulation considers the damping influence of oil on the ocean waves and its physical properties. It calculates the radiance contrast of the sea surface polluted by the oil film in relation to a clean sea surface for the SWIR spectral band. Our computer simulation combines the 3D simulation of a maritime scene (open clear sea/clear sky) with an oil film at the sea surface. The basic geometry of a clean sea surface is modeled by a composition of smooth wind driven gravity waves. Oil on the sea surface attenuates the capillary and short gravity waves modulating the wave power density spectrum of these waves. The radiance of the maritime scene is calculated in the SWIR spectral band with the emitted sea surface radiance and the specularly reflected sky radiance as components. Wave hiding and shadowing, especially occurring at low viewing angles, are considered. The specular reflection of the sky radiance at the clean sea surface is modeled by an analytical statistical bidirectional reflectance distribution function (BRDF) of the sea surface. For oil at the sea surface, a specific BRDF is used influenced by the reduced surface roughness, i.e., the modulated wave density spectrum. The radiance contrast of an oil film in relation to the clean sea surface is calculated for different viewing angles, wind speeds, and oil types characterized by their specific physical properties.

Spectral and spatial properties of polarized light reflections from the arms of squid (Loligo pealeii) and cuttlefish (Sepia officinalis L.).

Science.gov (United States)

Chiou, Tsyr-Huei; Mäthger, Lydia M; Hanlon, Roger T; Cronin, Thomas W

2007-10-01

On every arm of cuttlefish and squid there is a stripe of high-reflectance iridophores that reflects highly polarized light. Since cephalopods possess polarization vision, it has been hypothesized that these polarized stripes could serve an intraspecific communication function. We determined how polarization changes when these boneless arms move. By measuring the spectral and polarizing properties of the reflected light from samples at various angles of tilt and rotation, we found that the actual posture of the arm has little or no effect on partial polarization or the e-vector angle of the reflected light. However, when the illumination angle changed, the partial polarization of the reflected light also changed. The spectral reflections of the signals were also affected by the angle of illumination but not by the orientation of the sample. Electron microscope samples showed that these stripes are composed of several groups of multilayer platelets within the iridophores. The surface normal to each group is oriented at a different angle, which produces essentially constant reflection of polarized light over a range of viewing angles. These results demonstrate that cuttlefish and squid could send out reliable polarization signals to a receiver regardless of arm orientation.

Dynamics of continuous-time bidirectional associative memory neural networks with impulses and their discrete counterparts

International Nuclear Information System (INIS)

Huo Haifeng; Li Wantong

2009-01-01

This paper is concerned with the global stability characteristics of a system of equations modelling the dynamics of continuous-time bidirectional associative memory neural networks with impulses. Sufficient conditions which guarantee the existence of a unique equilibrium and its exponential stability of the networks are obtained. For the goal of computation, discrete-time analogues of the corresponding continuous-time bidirectional associative memory neural networks with impulses are also formulated and studied. Our results show that the above continuous-time and discrete-time systems with impulses preserve the dynamics of the networks without impulses when we make some modifications and impose some additional conditions on the systems, the convergence characteristics dynamics of the networks are preserved by both continuous-time and discrete-time systems with some restriction imposed on the impulse effect.

Three-port bi-directional converter for electric vehicles: focus on high-frequency coaxial transformer

NARCIS (Netherlands)

Waltrich, G.; Duarte, J.L.; Hendrix, M.A.M.; Paulides, J.J.H.

2010-01-01

A bi-directional multi-port converter can accommodate various energy storages and sources. Therefore, a multiport converter will be a good candidate for application as a future universal converter for (hybrid) electrical vehicles or local distribution systems. The main design challenge of the

Coordinated Operation of the Electricity and Natural Gas Systems with Bi-directional Energy Conversion

DEFF Research Database (Denmark)

Zeng, Qing; Zhang, Baohua; Fang, Jiakun

2017-01-01

A coordinated operation of the natural gas and electricity network with bi-directional energy conversion is expected to accommodate high penetration levels of renewables. This work focuses on the unified optimal operation of the integrated natural gas and electricity system considering the network...

The Improved Dual-view Field Goniometer System FIGOS

Directory of Open Access Journals (Sweden)

Klaus I. Itten

2008-08-01

Full Text Available In spectrodirectional Remote Sensing (RS the Earth’s surface reflectance characteristics are studied by means of their angular dimensions. Almost all natural surfaces exhibit an individual anisotropic reflectance behaviour due to the contrast between the optical properties of surface elements and background and the geometric surface properties of the observed scene. The underlying concept, which describes the reflectance characteristic of a specific surface area, is called the bidirectional reflectance distribution function (BRDF. BRDF knowledge is essential for both correction of directional effects in RS data and quantitative retrieval of surface parameters. Ground-based spectrodirectional measurements are usually performed with goniometer systems. An accurate retrieval of the bidirectional reflectance factors (BRF from field goniometer measurements requires hyperspectral knowledge of the angular distribution of the reflected and the incident radiation. However, prior to the study at hand, no operational goniometer system was able to fulfill this requirement. This study presents the first dual-view field goniometer system, which is able to simultaneously collect both the reflected and the incident radiation at high angular and spectral resolution and, thus, providing the necessary spectrodirectional datasets to accurately retrieve the surface specific BRF. Furthermore, the angular distribution of the incoming diffuse radiation is characterized for various atmospheric conditions and the BRF retrieval is performed for an artificial target and compared to laboratory spectrodirectional measurement results obtained with the same goniometer system. Suggestions for further improving goniometer systems are given and the need for intercalibration of various goniometers as well as for standardizing spectrodirectional measurements is expressed.

Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface

Energy Technology Data Exchange (ETDEWEB)

Adib, Ehsan; Farzanehfard, Hosein [Dept. of Electrical and Computer Engineering, Isfahan Univ. of Technology (Iran)

2009-12-15

In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis. (author)

On uniform resampling and gaze analysis of bidirectional texture functions

Czech Academy of Sciences Publication Activity Database

Filip, Jiří; Chantler, M.J.; Haindl, Michal

2009-01-01

Roč. 6, č. 3 (2009), s. 1-15 ISSN 1544-3558 R&D Projects: GA MŠk 1M0572; GA ČR GA102/08/0593 Grant - others:EC Marie Curie(BE) 41358 Institutional research plan: CEZ:AV0Z10750506 Keywords : BTF * texture * eye tracking Subject RIV: BD - Theory of Information Impact factor: 1.447, year: 2009 http://library.utia.cas.cz/separaty/2009/RO/haindl-on uniform resampling and gaze analysis of bidirectional texture functions.pdf

Bidirectional Relations of Impulsive Personality and Alcohol Use Across Three Waves of Data Collection.

Science.gov (United States)

Kaiser, Alison J; Davis, Heather A; Milich, Richard; Smith, Gregory T; Charnigo, Richard

2018-06-11

To explore the bidirectional relations between alcohol use and three impulsive personality traits, to advance understanding of risk processes. 525 college students (mean age = 18.95 years) recruited in August 2008 and 2009 and followed up annually for three years. Personality and past/current substance use were assessed. T2 sensation seeking mediated the predictive relationship between T1 and T3 alcohol use, and T2 alcohol use mediated the predictive relationship between T1 and T3 sensation seeking. In addition, T2 alcohol problems mediated the predictive relationship between T1 alcohol use and T3 negative urgency. Findings support a bidirectional relationship between sensation seeking and alcohol use, and drinking anticipates drinking problems, which predict increases in negative urgency. For some individuals, there appears to be an ongoing process of increased risk in the form of increases in both drinking and high-risk personality traits.

Bi-directional gene set enrichment and canonical correlation analysis identify key diet-sensitive pathways and biomarkers of metabolic syndrome

Directory of Open Access Journals (Sweden)

Gaora Peadar Ó

2010-10-01

Full Text Available Abstract Background Currently, a number of bioinformatics methods are available to generate appropriate lists of genes from a microarray experiment. While these lists represent an accurate primary analysis of the data, fewer options exist to contextualise those lists. The development and validation of such methods is crucial to the wider application of microarray technology in the clinical setting. Two key challenges in clinical bioinformatics involve appropriate statistical modelling of dynamic transcriptomic changes, and extraction of clinically relevant meaning from very large datasets. Results Here, we apply an approach to gene set enrichment analysis that allows for detection of bi-directional enrichment within a gene set. Furthermore, we apply canonical correlation analysis and Fisher's exact test, using plasma marker data with known clinical relevance to aid identification of the most important gene and pathway changes in our transcriptomic dataset. After a 28-day dietary intervention with high-CLA beef, a range of plasma markers indicated a marked improvement in the metabolic health of genetically obese mice. Tissue transcriptomic profiles indicated that the effects were most dramatic in liver (1270 genes significantly changed; p Conclusion Bi-directional gene set enrichment analysis more accurately reflects dynamic regulatory behaviour in biochemical pathways, and as such highlighted biologically relevant changes that were not detected using a traditional approach. In such cases where transcriptomic response to treatment is exceptionally large, canonical correlation analysis in conjunction with Fisher's exact test highlights the subset of pathways showing strongest correlation with the clinical markers of interest. In this case, we have identified selenoamino acid metabolism and steroid biosynthesis as key pathways mediating the observed relationship between metabolic health and high-CLA beef. These results indicate that this type of

Activity-Dependent Bidirectional Regulation of GAD Expression in a Homeostatic Fashion Is Mediated by BDNF-Dependent and Independent Pathways

Science.gov (United States)

Hanno-Iijima, Yoko; Tanaka, Masami; Iijima, Takatoshi

2015-01-01

Homeostatic synaptic plasticity, or synaptic scaling, is a mechanism that tunes neuronal transmission to compensate for prolonged, excessive changes in neuronal activity. Both excitatory and inhibitory neurons undergo homeostatic changes based on synaptic transmission strength, which could effectively contribute to a fine-tuning of circuit activity. However, gene regulation that underlies homeostatic synaptic plasticity in GABAergic (GABA, gamma aminobutyric) neurons is still poorly understood. The present study demonstrated activity-dependent dynamic scaling in which NMDA-R (N-methyl-D-aspartic acid receptor) activity regulated the expression of GABA synthetic enzymes: glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67). Results revealed that activity-regulated BDNF (brain-derived neurotrophic factor) release is necessary, but not sufficient, for activity-dependent up-scaling of these GAD isoforms. Bidirectional forms of activity-dependent GAD expression require both BDNF-dependent and BDNF-independent pathways, both triggered by NMDA-R activity. Additional results indicated that these two GAD genes differ in their responsiveness to chronic changes in neuronal activity, which could be partially caused by differential dependence on BDNF. In parallel to activity-dependent bidirectional scaling in GAD expression, the present study further observed that a chronic change in neuronal activity leads to an alteration in neurotransmitter release from GABAergic neurons in a homeostatic, bidirectional fashion. Therefore, the differential expression of GAD65 and 67 during prolonged changes in neuronal activity may be implicated in some aspects of bidirectional homeostatic plasticity within mature GABAergic presynapses. PMID:26241953

Effect of titanium dioxide (TiO{sub 2}) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

Energy Technology Data Exchange (ETDEWEB)

Wang, Shichao; Zhang, Jun, E-mail: zhangjun@njtech.edu.cn

2014-12-25

Highlights: • HDPE/TiO{sub 2} composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO{sub 2} composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO{sub 2}) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO{sub 2} particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO{sub 2} particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO{sub 2} particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO{sub 2} particles in HDPE matrix. It was found the rutile TiO{sub 2} could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result.

Reflectance spectra of subarctic lichens

International Nuclear Information System (INIS)

Petzold, D.E.; Goward, S.N.

1988-01-01

Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the mid latitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 μm, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future. (author)

Reflectance spectra of subarctic lichens

Science.gov (United States)

Petzold, Donald E.; Goward, Samuel N.

1988-01-01

Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the midlatitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 microns, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future.

High Efficient Bidirectional Battery Converter for residential PV Systems

DEFF Research Database (Denmark)

Pham, Cam; Kerekes, Tamas; Teodorescu, Remus

2012-01-01

Photovoltaic (PV) installation is suited for the residential environment and the generation pattern follows the distribution of residential power consumption in daylight hours. In the cases of unbalance between generation and demand, the Smart PV with its battery storage can absorb or inject...... the power to balance it. High efficient bidirectional converter for the battery storage is required due high system cost and because the power is processed twice. A 1.5kW prototype is designed and built with CoolMOS and SiC diodes, >;95% efficiency has been obtained with 200 kHz hard switching....

Bidirectional Quantum Secure Direct Communication Network Protocol with Hyperentanglement

International Nuclear Information System (INIS)

Gu Bin; Chen Yulin; Huang Yugai; Fang Xia

2011-01-01

We propose a bidirectional quantum secure direct communication (QSDC) network protocol with the hyperentanglment in both the spatial-mode ad the polarization degrees of freedom of photon pairs which can in principle be produced with a beta barium borate crystal. The secret message can be encoded on the photon pairs with unitary operations in these two degrees of freedom independently. Compared with other QSDC network protocols, our QSDC network protocol has a higher capacity as each photon pair can carry 4 bits of information. Also, we discuss the security of our QSDC network protocol and its feasibility with current techniques. (general)

Bidirectional relationship between time preference and adolescent smoking and alcohol use: Evidence from longitudinal data.

Science.gov (United States)

Do, Young Kyung; Shin, Eunhae

2017-07-01

Scholarly interest in time preference as a potential predictor of risky health behaviors in adolescents has increased in recent years. However, most of the existing literature is limited due to the exclusive reliance on cross-sectional data, precluding the possibility of establishing the direction of causality. Using longitudinal data from the Korea Youth Panel Survey (2003-7), which followed up a nationally representative sample of 3449 adolescents aged 14years for five years, this study examines a bidirectional relationship between time preference and smoking and drinking behaviors among adolescents. We used discrete time hazard models of smoking and drinking initiation as a function of time preference measured at the baseline and fixed-effects ordered logit model of time preference, respectively. Our measure of time preference was derived from the survey question on a hypothetical choice between immediate enjoyment today and likely higher scores on an exam tomorrow. The overall results provide evidence on the bidirectional relationship; that is, higher time discounting (i.e., greater relative preference for present utility over future utility) results in an increased risk of engaging in smoking and drinking, and conversely, adopting such behaviors leads to a higher discount rate. The bidirectional relationship may function as a mechanism for adolescents to engage in increased smoking and drinking or additional negative health behaviors via gateway effects, strengthening the case for preventing the initiation of risky health behaviors among adolescents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bidirectional-Convolutional LSTM Based Spectral-Spatial Feature Learning for Hyperspectral Image Classification

Directory of Open Access Journals (Sweden)

Qingshan Liu

2017-12-01

Full Text Available This paper proposes a novel deep learning framework named bidirectional-convolutional long short term memory (Bi-CLSTM network to automatically learn the spectral-spatial features from hyperspectral images (HSIs. In the network, the issue of spectral feature extraction is considered as a sequence learning problem, and a recurrent connection operator across the spectral domain is used to address it. Meanwhile, inspired from the widely used convolutional neural network (CNN, a convolution operator across the spatial domain is incorporated into the network to extract the spatial feature. In addition, to sufficiently capture the spectral information, a bidirectional recurrent connection is proposed. In the classification phase, the learned features are concatenated into a vector and fed to a Softmax classifier via a fully-connected operator. To validate the effectiveness of the proposed Bi-CLSTM framework, we compare it with six state-of-the-art methods, including the popular 3D-CNN model, on three widely used HSIs (i.e., Indian Pines, Pavia University, and Kennedy Space Center. The obtained results show that Bi-CLSTM can improve the classification performance by almost 1.5 % as compared to 3D-CNN.

Field Tests on Hydrodynamic and Hybrid Operation of a Bidirectional Thrust Bearing of a Pump-Turbine

Directory of Open Access Journals (Sweden)

Michał Wasilczuk

2017-12-01

Full Text Available In vertical shaft pump turbines operating in pumped storage power plants an important role is played by a thrust bearing. Due to the bidirectional character of operation, thrust bearing tilting pads have to be supported symmetrically, which is known to be unfavourable from the point of view of their performance. Large thrust bearings have to be carefully designed so as to minimise excessive thermo-elastic pad deformations. The research into fluid film thrust bearings has been quite extensive over the years, comprising theoretical studies of bearing properties with the use of more and more sophisticated calculation codes. On the other hand, the availability of experimental field data on bearing operation is limited, for obvious reasons. In this paper the authors present part of the results of extensive field tests of a large bearing of a pump-turbine they have conducted in a pumped storage power plant. Hopefully this data will be of interest to other researchers to compare theoretical predictions to measurement data.

An Improved Method For Retrieving Land Surface Albedo Over Rugged Terrain

NARCIS (Netherlands)

Gao, B.; Jia, L.; Menenti, M.

2014-01-01

Land surface albedo is a very important parameter, which can be derived from a bidirectional reflectance distribution function (BRDF) model with angular integration of BRDF in a particular distribution of downward solar irradiance. The Algorithm for MODIS Bidirectional Reflectance Anisotropic of

Quantitative analysis of reflection electron energy loss spectra to determine electronic and optical properties of Fe–Ni alloy thin films

International Nuclear Information System (INIS)

Tahir, Dahlang; Oh, Sukh Kun; Kang, Hee Jae; Tougaard, Sven

2016-01-01

Highlights: • Electronic and optical properties of Fe-Ni alloy thin films grown on Si (1 0 0) were studied via quantitative analyses of reflection electron energy loss spectra (REELS). • The energy loss functions (ELF) are dominated by a plasmon peak at 23.6 eV for Fe and moves gradually to lower energies in Fe-Ni alloys towards the bulk plasmon energy of Ni at 20.5 eV. • Fe has a strong effect on the dielectric and optical properties of Fe-Ni alloy thin films even for an alloy with 72% Ni. Electronic and optical properties of Fe-Ni alloy thin films grown on Si (1 0 0) were studied via quantitative analyses of reflection electron energy loss spectra (REELS). - Abstract: Electronic and optical properties of Fe–Ni alloy thin films grown on Si (1 0 0) by ion beam sputter deposition were studied via quantitative analyses of reflection electron energy loss spectra (REELS). The analysis was carried out by using the QUASES-XS-REELS and QUEELS-ε(k,ω)-REELS softwares to determine the energy loss function (ELF) and the dielectric functions and optical properties by analyzing the experimental spectra. For Ni, the ELF shows peaks around 3.6, 7.5, 11.7, 20.5, 27.5, 67 and 78 eV. The peak positions of the ELF for Fe_2_8Ni_7_2 are similar to those of Fe_5_1Ni_4_9, even though there is a small peak shift from 18.5 eV for Fe_5_1Ni_4_9 to 18.7 eV for Fe_2_8Ni_7_2. A plot of n, k, ε_1, and ε_2 shows that the QUEELS-ε(k,ω)-REELS software for analysis of REELS spectra is useful for the study of optical properties of transition metal alloys. For Fe–Ni alloy with high Ni concentration (Fe_2_8Ni_7_2), ε_1, and ε_2 have strong similarities with those of Fe. This indicates that the presence of Fe in the Fe–Ni alloy thin films has a strong effect.

Reflection properties of hydrogen ions at helium irradiated tungsten surfaces

International Nuclear Information System (INIS)

Doi, K; Tawada, Y; Kato, S; Sasao, M; Kenmotsu, T; Wada, M; Lee, H T; Ueda, Y; Tanaka, N; Kisaki, M; Nishiura, M; Matsumoto, Y; Yamaoka, H

2016-01-01

Nanostructured W surfaces prepared by He bombardment exhibit characteristic angular distributions of hydrogen ion reflection upon injection of 1 keV H + beam. A magnetic momentum analyzer that can move in the vacuum chamber has measured the angular dependence of the intensity and the energy of reflected ions. Broader angular distributions were observed for He-irradiated tungsten samples compared with that of the intrinsic polycrystalline W. Both intensity and energy of reflected ions decreased in the following order: the polycrystalline W, the He-bubble containing W, and the fuzz W. Classical trajectory Monte Carlo simulations based on Atomic Collision in Amorphous Target code suggests that lower atom density near the surface can make the reflection coefficients lower due to increasing number of collisions. (paper)

A Four-Phase High Voltage Conversion Ratio Bidirectional DC-DC Converter for Battery Applications

Directory of Open Access Journals (Sweden)

Li-Kun Xue

2015-06-01

Full Text Available This study presents a four-phase interleaved high voltage conversion ratio bidirectional DC-DC converter circuit based on coupled inductors and switched capacitors, which can eliminate the defects of conventional high voltage conversion ratio bidirectional DC-DC converters in terms of high-voltage/current stress, less efficiency and low-power limitation. Parallel channels are used to reduce current stress at the low-voltage side and series connected switched capacitors are used to enlarge voltage conversion ratio, reduce voltage stress and achieve auto current sharing. This paper proposes the operation principle, feature analysis and optimization design considerations. On this basis the objectives of high voltage conversion ratio, low voltage/current stress, high power density, high efficiency and high-power applications can be achieved. Some experimental results based on a 500 W prototype converter (24 V to 48 V at low-voltage side, 400 V at high-voltage side are given to verify the theoretical analysis and the effectiveness of the proposed converter.

ESTABLISHING BRDF CALIBRATION CAPABILITIES THROUGH SHORTWAVE INFRARED

OpenAIRE

Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

2017-01-01

Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Distribution Functions (BRDFs) of the laboratory and flight diffusers used in their pre-flight and on-orbit calibrations. This paper advances that initial work and presents a comparison of spectral Bidirectional Reflectance Distribution Function (BRDF) and Directional Hemispherical Reflectance (DHR) of Spectralon*, a common material for laborato...

Visible and near-infrared radiative properties of vertically aligned multi-walled carbon nanotubes

International Nuclear Information System (INIS)

Wang, X J; Zhang, Z M; Flicker, J D; Ready, W J; Lee, B J

2009-01-01

This work investigates the reflection and scattering from vertically aligned carbon nanotubes, fabricated on silicon substrate using thermally enhanced chemical vapor deposition with both tip-growth and base-growth mechanisms. The directional-hemispherical reflectance in the visible and near-infrared wavelengths was measured with an integrating sphere. The polarization-dependent bidirectional reflectance distribution function was characterized with a laser scatterometer at the wavelength of 635 nm. The effective medium theory was used to elucidate the mechanism of high absorptance (greater than 0.97 in the spectral region from 400 to 1800 nm) of the multi-walled carbon nanotube samples. It is observed that scattering by impurities on the top of the nanotubes, by the nanotube tips, and by defects and misalignment can significantly increase the reflectance and introduce retroreflection. This study may facilitate application of carbon nanotubes in pyroelectric detectors as well as thermophotovoltaic emitters and absorbers.

Design and implementation of a bidirectional current-controlled voltage-regulated DC-DC switched-mode converter

CSIR Research Space (South Africa)

Coetzer, A

2016-01-01

Full Text Available The design and implementation of a bidirectional current-controlled voltage-regulated DC-DC converter is presented. The converter is required to connect a battery of electrochemical cells (the battery) to an asynchronous motor-drive unit via a...

The Bidirectional Relationship between Diabetes and Depression: A Literature Review.