Planarization of metal films for multilevel interconnects

DOEpatents

Tuckerman, D.B.

1985-06-24

In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping lase pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

Planarization of metal films for multilevel interconnects

DOEpatents

Tuckerman, David B.

1987-01-01

In the fabrication of multilevel integrated circuits, each metal layer is anarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

Planarization of metal films for multilevel interconnects

DOEpatents

Tuckerman, David B.

1989-01-01

In the fabrication of multilevel integrated circuits, each metal layer is anarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

Planarization of metal films for multilevel interconnects

DOEpatents

Tuckerman, D.B.

1985-08-23

In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

Planarization of metal films for multilevel interconnects

DOEpatents

Tuckerman, D.B.

1989-03-21

In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration. 6 figs.

Model and particle-in-cell simulation of ion energy distribution in collisionless sheath

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Zhuwen, E-mail: zzwwdxy@gznc.edu.cn; Key Laboratory of Photoelectron Materials Design and Simulation in Guizhou Province, Guiyang 550018; Scientific Research Innovation Team in Plasma and Functional Thin Film Materials in Guizhou Province, Guiyang 550018

2015-06-15

In this paper, we propose a self-consistent theoretical model, which is described by the ion energy distributions (IEDs) in collisionless sheaths, and the analytical results for different combined dc/radio frequency (rf) capacitive coupled plasma discharge cases, including sheath voltage errors analysis, are compared with the results of numerical simulations using a one-dimensional plane-parallel particle-in-cell (PIC) simulation. The IEDs in collisionless sheaths are performed on combination of dc/rf voltage sources electrodes discharge using argon as the process gas. The incident ions on the grounded electrode are separated, according to their different radio frequencies, and dc voltages on a separated electrode, themore » IEDs, and widths of energy in sheath and the plasma sheath thickness are discussed. The IEDs, the IED widths, and sheath voltages by the theoretical model are investigated and show good agreement with PIC simulations.« less

Fracture and crack growth in orthotropic laminates. Part 1: Analysis of a hybrid, unidirectional laminate with damage

NASA Technical Reports Server (NTRS)

Goree, J. G.

1982-01-01

The fracture behavior of unifirectional hybrid (buffer strip) composite laminates is studied. Three particular solutions are discussed: (1) broken fibers in a unidirectional half plane; (2) adjoined half planes of different fiber and matrix properties and (3) the solution of two half planes bounding a third distinct region of finite width. This finite width region represents a buffer strip and the potential of this strip to arrest a crack that originates in one of the half planes is investigated. The analysis is based on a materials modeling approach using the classical shear lag assumption to described the stress transfer between fibers. Explicit fiber and matrix properties of the three regions are retained and changes in the laminate behavior as a function of the relative material properties, buffer strip width and initial crack length are discussed.

Ground-state entropy of the potts antiferromagnet with next-nearest-neighbor spin-spin couplings on strips of the square lattice

PubMed

Chang; Shrock

2000-10-01

We present exact calculations of the zero-temperature partition function (chromatic polynomial) and W(q), the exponent of the ground-state entropy, for the q-state Potts antiferromagnet with next-nearest-neighbor spin-spin couplings on square lattice strips, of width L(y)=3 and L(y)=4 vertices and arbitrarily great length Lx vertices, with both free and periodic boundary conditions. The resultant values of W for a range of physical q values are compared with each other and with the values for the full two-dimensional lattice. These results give insight into the effect of such nonnearest-neighbor couplings on the ground-state entropy. We show that the q=2 (Ising) and q=4 Potts antiferromagnets have zero-temperature critical points on the Lx-->infinity limits of the strips that we study. With the generalization of q from Z+ to C, we determine the analytic structure of W(q) in the q plane for the various cases.

The 2009-2010 Guerrero Slow Slip Event Monitored by InSAR, Using Time Series Approach

NASA Astrophysics Data System (ADS)

Bacques, G.; Pathier, E.; Lasserre, C.; Cotton, F.; Radiguet, M.; Cycle Sismique et Déformations Transitoires

2011-12-01

The Guerrero seismic gap is located along the Pacific coast of Mexico in a subduction zone where Cocos plate subducts under the North American plate with a 5.5 cm per year convergence rate. Along this 100 km width band located between Acapulco (East side) and Zihuatanejo (West side), no major earthquake occurred since at least 1911. In contrast, the surrounding areas of the Guerrero gap has been the location of large seismic events during the last century like the 1985 one's (Mw 8), which affected Mexico City. Considering the plate convergence rate, a 5 meters slip deficit has been estimated at this gap location since the last major earthquake (Lowry et al. 1998), making a large earthquake possible at this spot. However, the Guerrero gap was the setting of four slow slip events (SSE) with an approximately four years periodicity (1998, 2002, 2006, 2009-2010) since it was instrumented by GPS permanent network in January 1997. Slow slip events and their associated ground displacements are commonly interpreted as aseismic slips on the deeper part of the subduction plane. One of the main issues concerning that phenomenon, deals with the way that strain accumulated on the deeper part is released on the upper part of the subduction plane, which corresponds to the seismogenic zone. As a consequence, the slip distribution upon the subduction plane associated to the Guerrero SSE represents relevant information concerning the local seismic hazard. To address this issue, geodetic measurements from GPS and/or space-borne SAR differential interferometry (DInSAR) can be used to retrieve the SSE slip distribution on the subduction plane from the ground deformation measurements as it has been done for the 2006 event previously studied. In this work, we focused on the 2009-2010 SSE on Guerrero by processing DInSAR data (C band Envisat data were processed using the small baseline approach method NSBAS based upon ROI-pac) as previously done for the 2006 event but improved by adding a Time Series approach. Time Series approach is useful for monitoring ground deformation evolution during the slow slip events and makes the slip propagation mapping upon the subduction plane a promising goal. Here we present our first results concerning the 2009-2010 slow slip events, particularly the distribution of the cumulative surface displacement in LOS (satellite Line Of Sight), the slip distribution associated on the fault plane and the ground deformation evolution obtained. Finally, we open the discussion with a first comparison between the 2009-2010 and the 2006 events that reveal some differences concerning the amplitude and the distribution of the ground deformation.

Metal Patch Antenna

NASA Technical Reports Server (NTRS)

Chamberlain, Neil F. (Inventor); Zawadzki, Mark S. (Inventor); Hodges, Richard E. (Inventor)

2012-01-01

Disclosed herein is a patch antenna comprises a planar conductive patch attached to a ground plane by a support member, and a probe connector in electrical communication with the conductive patch arranged to conduct electromagnetic energy to or from the conductive patch, wherein the conductive patch is disposed essentially parallel to the ground plane and is separated from the ground plane by a spacing distance; wherein the support member comprises a plurality of sides disposed about a central axis oriented perpendicular to the conductive patch and the ground plane; wherein the conductive patch is solely supported above the ground plane by the support member; and wherein the support member provides electrical communication between the planer conductive patch and the ground plane.

Orbitally excited spectra and decay of cc¯ meson

NASA Astrophysics Data System (ADS)

Chaturvedi, Raghav; Rai, A. K.

2018-05-01

We use the hydrogen like trial wave function for computation of the mass spectra and decay properties of charmonia within the framework of phenomenological quark anti-quark Coulomb plus power potential with varying potential index from 0.5 to 2.0. The spin-spin hyperfine interaction is considered to incorporate splitting of the ground and radially excited states energy levels, further spin-orbit and tensor interactions are employed to calculate the masses of orbitally excited states. We construct the Regge trajectories from the mass spectra in (J, M2) and (nr, M2) planes. We also compute γγ decay width of P wave states of cc¯.

Planarization of metal films for multilevel interconnects by pulsed laser heating

DOEpatents

Tuckerman, David B.

1987-01-01

In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

Evaluation of arch width variations among different skeletal patterns in South Indian population.

PubMed

Prasad, Mandava; Kannampallil, Senny Thomas; Talapaneni, Ashok Kumar; George, Suja Ani; Shetty, Sharath Kumar

2013-01-01

Anterior cranial base can be taken as a reference line (SN) to determine the steepness of mandibular plane. Subjects with high mandibular plane angle tend to have a long face and one with low MP-SN angle has a shorter face. This study was done to investigate if dental arch widths correlated with vertical facial types and if there are any differences in arch widths between untreated male and female adults in South Indian population. Lateral cephalogram and dental casts were obtained from 180 untreated South Indian adults (90 males and 90 females) above 18 year old with no cross bite, minimal crowding and spacing. The angle between the anterior cranial base and the mandibular plane was measured on lateral cephalogram of each patient. Dental casts were used to obtain comprehensive dental measurements including maxillary and mandibular inter canine, inter premolar and inter molar widths, as well as amount of crowding or spacing. The results showed that male arch widths were significantly larger than those of females (P < 0.05) and there was a significant decrease in inter arch width as the MP-SN angle increased in untreated adult South Indian population. The results obtained in our study when compared with studies done in other population groups showed that there is difference in inter arch widths according to ethnicity and race. It was concluded that the dental arch width is associated with gender, race and vertical facial morphology. Thus using individualized arch wires according to each patient's pre treatment arch form and width is suggested during orthodontic treatment.

Evaluation of arch width variations among different skeletal patterns in South Indian population

PubMed Central

Prasad, Mandava; Kannampallil, Senny Thomas; Talapaneni, Ashok Kumar; George, Suja Ani; Shetty, Sharath Kumar

2013-01-01

Background: Anterior cranial base can be taken as a reference line (SN) to determine the steepness of mandibular plane. Subjects with high mandibular plane angle tend to have a long face and one with low MP-SN angle has a shorter face. Objective: This study was done to investigate if dental arch widths correlated with vertical facial types and if there are any differences in arch widths between untreated male and female adults in South Indian population. Materials and Methods: Lateral cephalogram and dental casts were obtained from 180 untreated South Indian adults (90 males and 90 females) above 18 year old with no cross bite, minimal crowding and spacing. The angle between the anterior cranial base and the mandibular plane was measured on lateral cephalogram of each patient. Dental casts were used to obtain comprehensive dental measurements including maxillary and mandibular inter canine, inter premolar and inter molar widths, as well as amount of crowding or spacing. Results: The results showed that male arch widths were significantly larger than those of females (P < 0.05) and there was a significant decrease in inter arch width as the MP-SN angle increased in untreated adult South Indian population. The results obtained in our study when compared with studies done in other population groups showed that there is difference in inter arch widths according to ethnicity and race. Conclusion: It was concluded that the dental arch width is associated with gender, race and vertical facial morphology. Thus using individualized arch wires according to each patient's pre treatment arch form and width is suggested during orthodontic treatment. PMID:23633842

Design And Simulation Of Microstrip Antenna Of 2.4 GHz Using CST

NASA Astrophysics Data System (ADS)

Thakur, O. P.; Kushwaha, Alok K.

2011-12-01

This article describes the design, fabrication and testing of micro strip patch antennas operating at 2.4 GHz. Consideration is given on practical design technique, including substrate selection and antenna measurements. It is emphasised to the radiation properties of the antennas—the radiation pattern and polarization purity. A micro strip patch antenna consists of a very thin metallic patch placed a small fraction of a wavelength above a conducting ground-plane. The patch and ground-plane are separated by a dielectric. The patch conductor is normally copper and can assume any shape, but simple geometries generally are used, and this simplifies the analysis and performance prediction. The patches are usually photo etched on the dielectric substrate. The substrate is usually non-magnetic. The relative permittivity of the substrate is normally in the region between 1 and 4, which enhances the fringing fields that account for radiation, but higher values may be used in special circumstances. Due to its simple geometry, the half wave rectangular patch is the most commonly used micro strip antenna. It is characterized by its length L, width w and thickness h. The simplest method of feeding the patch is by a coplanar micro strip line, also photo etched on the substrate. Coaxial feeds are also widely used.

Effects of finite ground plane on the radiation characteristics of a circular patch antenna

NASA Astrophysics Data System (ADS)

Bhattacharyya, Arun K.

1990-02-01

An analytical technique to determine the effects of finite ground plane on the radiation characteristics of a microstrip antenna is presented. The induced currents on the ground plane and on the upper surface of the patch are determined from the discontinuity of the near field produced by the equivalent magnetic current source on the physical aperture of the patch. The radiated fields contributed by the induced current on the ground plane and the equivalent sources on the physical aperture yield the radiation pattern of the antenna. Radiation patterns of the circular patch with finite ground plane size are computed and compared with the experimental data, and the agreement is found to be good. The radiation pattern, directive gain, and input impedance are found to vary widely with the ground plane size.

Front-Side Microstrip Line Feeding a Raised Antenna Patch

NASA Technical Reports Server (NTRS)

Hodges, Richard; Hoppe, Daniel

2005-01-01

An improved design concept for a printed-circuit patch antenna and the transmission line that feeds the patch calls for (1) a microstrip transmission line on the front (radiative) side of a printed-circuit board based on a thin, high-permittivity dielectric substrate; (2) using the conductor covering the back side of the circuit board as a common ground plane for both the microstrip line and the antenna patch; (3) supporting the antenna patch in front of the circuit board on a much thicker, lower-permittivity dielectric spacer layer; and (4) connecting the microstrip transmission line to the patch by use of a thin wire or narrow ribbon that extends through the thickness of the spacer and is oriented perpendicularly to the circuit-board plane. The thickness of the substrate is typically chosen so that a microstrip transmission line of practical width has an impedance between 50 and 100 ohms. The advantages of this design concept are best understood in the context of the disadvantages of prior design concepts, as explained

Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane

DTIC Science & Technology

2014-07-01

Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane Peijun Li 1 and Aihua W. Wood 2 1 Department of...of the electromagnetic wave scattering by multiple open cavities, which are embedded in an infinite two-dimensional ground plane . By introducing a...equation, variational formulation. I. INTRODUCTION A cavity is referred to as a local perturbation of the infinite ground plane . Given the cavity

Direct observation of a Γ -X energy spectrum transition in narrow AlAs quantum wells

NASA Astrophysics Data System (ADS)

Khisameeva, A. R.; Shchepetilnikov, A. V.; Muravev, V. M.; Gubarev, S. I.; Frolov, D. D.; Nefyodov, Yu. A.; Kukushkin, I. V.; Reichl, C.; Tiemann, L.; Dietsche, W.; Wegscheider, W.

2018-03-01

Spectra of magnetoplasma excitations have been investigated in two-dimensional electron systems in AlAs quantum wells (QWs) of different widths. The magnetoplasma spectrum has been found to change profoundly when the quantum well width becomes thinner than 5.5 nm, indicating a drastic change in the conduction electron energy spectrum. The transformation can be interpreted in terms of transition from the in-plane strongly anisotropic Xx-Xy valley occupation to the out-of-plane isotropic Xz valley in the QW plane. Strong enhancement of the cyclotron effective mass over the band value in narrow AlAs QWs is reported.

Analysis of propeller-induced ground vortices by particle image velocimetry.

PubMed

Yang, Y; Sciacchitano, A; Veldhuis, L L M; Eitelberg, G

2018-01-01

The interaction between a propeller and its self-induced vortices originating on the ground is investigated in a scaled experiment. The velocity distribution in the flow field in two different planes containing the self-induced vortices is measured by particle image velocimetry (PIV). These planes are a wall-parallel plane in close proximity to the ground and a wall-normal plane just upstream of the propeller. Based on the visualization of the flow field in these two planes, the occurrence of ground vortices and its domain boundary are analysed. The elevation of the propeller from the ground and the thrust of the propeller are two parameters that determine the occurrence of ground vortices. The main features of the propeller inflow in the presence of the ground vortices are highlighted. Moreover, the analysis of the non-uniform inflow in the azimuthal direction shows that with increasing the propeller thrust coefficient and decreasing the elevation of the propeller above the ground, the variation of the inflow angle of the blade increases.

Radiation Characteristics of Cavity Backed Aperture Antennas in Finite Ground Plane Using the Hybrid FEM/MoM Technique and Geometrical Theory of Diffraction

NASA Technical Reports Server (NTRS)

Reddy, C. J.; Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.

1996-01-01

A technique using hybrid Finite Element Method (FEM)/Method of Moments (MoM), and Geometrical Theory of Diffraction (GTD) is presented to analyze the radiation characteristics of cavity fed aperture antennas in a finite ground plane. The cavity which excites the aperture is assumed to be fed by a cylindrical transmission line. The electromagnetic (EM) fields inside the cavity are obtained using FEM. The EM fields and their normal derivatives required for FEM solution are obtained using (1) the modal expansion in the feed region and (2) the MoM for the radiating aperture region(assuming an infinite ground plane). The finiteness of the ground plane is taken into account using GTD. The input admittance of open ended circular, rectangular, and coaxial line radiating into free space through an infinite ground plane are computed and compared with earlier published results. Radiation characteristics of a coaxial cavity fed circular aperture in a finite rectangular ground plane are verified with experimental results.

Searching for bumps and ellipses on the ground and in the sky: no advantage for the ground plane.

PubMed

Jóhannesson, Omar I; Sigurdardottir, Kristín Ósk; Kristjánsson, Arni

2013-11-01

A staple of modern theories of vision is that the visual system has evolved to perceive cues containing the most predictive information about the layout of the environment. This entails the prediction that - other things being equal - visual performance in a familiar setting should be superior to performance in an unfamiliar one. Visual performance should therefore be better on the familiar ground plane compared to an implied sky or wall plane. We tested this comparing visual search for stimuli presented in an implied ground plane with search on a 180° rotated search display so that the stimuli appeared in an implied "sky" plane, and with search in a random layout implying no depth. This was tested for stimuli with, or without, curvature discontinuities, that have previously been shown to be strong cues for shape analysis. Surprisingly, no advantage of the ground plane over the sky plane was observed, while a strong effect of layout regularity was seen. Similarly, in experiment 2 there was little effect of placing the stimuli on an implied wall plane compared to the ground or the sky. The results are not explained by assuming that curvature discontinuities are such strong cues that they overshadow any effect of depth-plane, since there was a strong effect of regular versus random layout, which should also have disappeared under this account. The results argue instead for a very strong effect of layout regularity, unrelated to environmental regularities in evolutionary history, since there was no ground-plane benefit. Copyright © 2013 Elsevier B.V. All rights reserved.

Spatial-temporal and modal analysis of propeller induced ground vortices by particle image velocimetry

NASA Astrophysics Data System (ADS)

Yang, Y.; Sciacchitano, A.; Veldhuis, L. L. M.; Eitelberg, G.

2016-10-01

During the ground operation of aircraft, there is potentially a system of vortices generated from the ground toward the propulsor, commonly denoted as ground vortices. Although extensive research has been conducted on ground vortices induced by turbofans which were simplified by suction tubes, these studies cannot well capture the properties of ground vortices induced by propellers, e.g., the flow phenomena due to intermittent characteristics of blade passing and the presence of slipstream of the propeller. Therefore, the investigation of ground vortices induced by a propeller is performed to improve understanding of these phenomena. The distributions of velocities in two different planes containing the vortices were measured by high frequency Particle Image Velocimetry. These planes are a wall-parallel plane in close proximity to the ground and a wall-normal plane upstream of the propeller. The instantaneous flow fields feature highly unsteady flow in both of these two planes. The spectral analysis is conducted in these two flow fields and the energetic frequencies are quantified. The flow fields are further evaluated by applying the Proper Orthogonal Decomposition analysis to capture the coherent flow structures. Consistent flow structures with strong contributions to the turbulent kinetic energy are noticed in the two planes.

Length divergence of the lattice thermal conductivity in suspended graphene nanoribbons

NASA Astrophysics Data System (ADS)

Majee, Arnab K.; Aksamija, Zlatan

2016-06-01

Thermal properties of graphene have attracted much attention, culminating in a recent measurement of its length dependence in ribbons up to 9 μ m long. In this paper, we use the improved Callaway model to solve the phonon Boltzmann transport equation while capturing both the resistive (umklapp, isotope, and edge roughness) and nonresistive (normal) contributions. We show that for lengths smaller than 100 μ m , scaling the ribbon length while keeping the width constant leads to a logarithmic divergence of thermal conductivity. The length dependence is driven primarily by a ballistic-to-diffusive transition in the in-plane (LA and TA) branches, while in the hydrodynamic regime when 10 μ m 100 μ m due to the coupling between in-plane and flexural modes. This coupling leads to renormalization of ZA phonon dispersion in the long-wavelength range, preventing further divergence of thermal conductivity. We also uncover a strong dependence on sample width, which we attribute to the interplay between nonresistive normal and diffusive edge scattering in the Poisseuille flow regime. We conclude that normal processes play a crucial role in the length and width dependence of thermal transport in graphene in the hydrodynamic regime and dictate the relative in-plane (LA+TA) to out-of-plane (ZA) contribution to transport.

The ground vortex flow field associated with a jet in a cross flow impinging on a ground plane for uniform and annular turbulent axisymmetric jets. M.S. Thesis

NASA Technical Reports Server (NTRS)

Cavage, William M.; Kuhlman, John M.

1993-01-01

An experimental study was conducted of the impingement of a single circular jet on a ground plane in a cross flow. This geometry is a simplified model of the interaction of propulsive jet exhaust from a V/STOL aircraft with the ground in forward flight. Jets were oriented normal to the cross flow and ground plane. Jet size, cross flow-to-jet velocity ratio, ground plane-to-jet board spacing, and jet exit turbulence level and mean velocity profile shape were all varied to determine their effects on the size of the ground vortex interaction region which forms on the ground plane, using smoke injection into the jet. Three component laser Doppler velocimeter measurements were made with a commercial three color system for the case of a uniform jet with exit spacing equal to 5.5 diameters and cross flow-to-jet velocity ratio equal to 0.11. The flow visualization data compared well for equivalent runs of the same nondimensional jet exit spacing and the same velocity ratio for different diameter nozzles, except at very low velocity ratios and for the larger nozzle, where tunnel blockage became significant. Variation of observed ground vortex size with cross flow-to-jet velocity ratio was consistent with previous studies. Observed effects of jet size and ground plane-to-jet board spacing were relatively small. Jet exit turbulence level effects were also small. However, an annular jet with a low velocity central core was found to have a significantly smaller ground vortex than an equivalent uniform jet at the same values of cross flow-to-jet velocity ratio and jet exit-to-ground plane spacing. This may suggest a means of altering ground vortex behavior somewhat, and points out the importance of proper simulation of jet exit velocity conditions. LV data indicated unsteady turbulence levels in the ground vortex in excess of 70 percent.

A novel robot for imposing perturbations during overground walking: mechanism, control and normative stepping responses.

PubMed

Olenšek, Andrej; Zadravec, Matjaž; Matjačić, Zlatko

2016-06-11

The most common approach to studying dynamic balance during walking is by applying perturbations. Previous studies that investigated dynamic balance responses predominantly focused on applying perturbations in frontal plane while walking on treadmill. The goal of our work was to develop balance assessment robot (BAR) that can be used during overground walking and to assess normative balance responses to perturbations in transversal plane in a group of neurologically healthy individuals. BAR provides three passive degrees of freedom (DoF) and three actuated DoF in pelvis that are admittance-controlled in such a way that the natural movement of pelvis is not significantly affected. In this study BAR was used to assess normative balance responses in neurologically healthy individuals by applying linear perturbations in frontal and sagittal planes and angular perturbations in transversal plane of pelvis. One way repeated measure ANOVA was used to statistically evaluate the effect of selected perturbations on stepping responses. Standard deviations of assessed responses were similar in unperturbed and perturbed walking. Perturbations in frontal direction evoked substantial pelvis displacement and caused statistically significant effect on step length, step width and step time. Likewise, perturbations in sagittal plane also caused statistically significant effect on step length, step width and step time but with less explicit impact on pelvis movement in frontal plane. On the other hand, except from substantial pelvis rotation angular perturbations did not have substantial effect on pelvis movement in frontal and sagittal planes while statistically significant effect was noted only in step length and step width after perturbation in clockwise direction. Results indicate that the proposed device can repeatedly reproduce similar experimental conditions. Results also suggest that "stepping strategy" is the dominant strategy for coping with perturbations in frontal plane, perturbations in sagittal plane are to greater extent handled by "ankle strategy" while angular perturbations in transversal plane do not pose substantial challenge for balance. Results also show that specific perturbation in general elicits responses that extend also to other planes of movement that are not directly associated with plane of perturbation as well as to spatio temporal parameters of gait.

49 CFR 571.10 - Designation of seating positions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... maximum width of a seating surface measured in a zone extending from a transverse vertical plane 150 mm (5.9 inches) behind the front leading surface of that seating surface to a transverse vertical plane... (5.5 inches), as measured in each transverse vertical plane within that measurement zone, or (B) A...

Neonatal line width in deciduous incisors from Neolithic, mediaeval and modern skeletal samples from north-central Poland.

PubMed

Kurek, Marta; Żądzińska, Elżbieta; Sitek, Aneta; Borowska-Strugińska, Beata; Rosset, Iwona; Lorkiewicz, Wiesław

2016-01-01

The neonatal line is usually the first accentuated incremental line visible on the enamel. The prenatal environment significantly contributes to the width of the neonatal line, influencing the pace of reaching post-delivery homeostasis by the newborn's organism. Studies of the enamel of the earliest developing deciduous teeth can provide an insight into the prenatal development and the perinatal conditions of children of past human populations, thus being an additional source contributing to consideration of the influence of prenatal and perinatal factors modifying growth processes. The aim of this study was to examine whether the neonatal line, reflecting the conditions of the prenatal and perinatal environment, differed between the Neolithic, the mediaeval and the modern populations from the Kujawy region in north-central Poland. The material consisted of longitudinally ground sections of 57 human deciduous incisors obtained from children aged 1.0-7.5 years representing three archaeological series from Brześć Kujawski site. All teeth were sectioned in the labio-linqual plane using a diamond blade (Buechler IsoMet 1000). Final specimens were observed with the microscope Delta Optical Evolution 300 at 10× and 40× magnifications. For each tooth, linear measurements of the neonatal line width were performed on its labial surface at the three levels from the cemento-enamel junction. No significant difference was found in the mean neonatal line width depending on the tooth type and archaeological site, although the thickest neonatal line characterised children from the Neolithic series. In all analysed series, the neonatal line width was diversified depending on the child's age at death. The value of Spearman's rank correlation coefficient calculated for the correlation between the child's age at death and the neonatal line width was statistically significant. A clear increase in the width of the neonatal line was thus observed along with a decrease in the child's age at death. Copyright © 2015 Elsevier GmbH. All rights reserved.

Accuracy of three-dimensional dental resin models created by fused deposition modeling, stereolithography, and Polyjet prototype technologies: A comparative study.

PubMed

Rebong, Raymund E; Stewart, Kelton T; Utreja, Achint; Ghoneima, Ahmed A

2018-05-01

The aim of this study was to assess the dimensional accuracy of fused deposition modeling (FDM)-, Polyjet-, and stereolithography (SLA)-produced models by comparing them to traditional plaster casts. A total of 12 maxillary and mandibular posttreatment orthodontic plaster casts were selected from the archives of the Orthodontic Department at the Indiana University School of Dentistry. Plaster models were scanned, saved as stereolithography files, and printed as physical models using three different three-dimensional (3D) printers: Makerbot Replicator (FDM), 3D Systems SLA 6000 (SLA), and Objet Eden500V (Polyjet). A digital caliper was used to obtain measurements on the original plaster models as well as on the printed resin models. Comparison between the 3D printed models and the plaster casts showed no statistically significant differences in most of the parameters. However, FDM was significantly higher on average than were plaster casts in maxillary left mixed plane (MxL-MP) and mandibular intermolar width (Md-IMW). Polyjet was significantly higher on average than were plaster casts in maxillary intercanine width (Mx-ICW), mandibular intercanine width (Md-ICW), and mandibular left mixed plane (MdL-MP). Polyjet was significantly lower on average than were plaster casts in maxillary right vertical plane (MxR-vertical), maxillary left vertical plane (MxL-vertical), mandibular right anteroposterior plane (MdR-AP), mandibular right vertical plane (MdR-vertical), and mandibular left vertical plane (MdL-vertical). SLA was significantly higher on average than were plaster casts in MxL-MP, Md-ICW, and overbite. SLA was significantly lower on average than were plaster casts in MdR-vertical and MdL-vertical. Dental models reconstructed by FDM technology had the fewest dimensional measurement differences compared to plaster models.

Feedforward ankle strategy of balance during quiet stance in adults

PubMed Central

Gatev, Plamen; Thomas, Sherry; Kepple, Thomas; Hallett, Mark

1999-01-01

We studied quiet stance investigating strategies for maintaining balance. Normal subjects stood with natural stance and with feet together, with eyes open or closed. Kinematic, kinetic and EMG data were evaluated and cross-correlated.Cross-correlation analysis revealed a high, positive, zero-phased correlation between anteroposterior motions of the centre of gravity (COG) and centre of pressure (COP), head and COG, and between linear motions of the shoulder and knee in both sagittal and frontal planes. There was a moderate, negative, zero-phased correlation between the anteroposterior motion of COP and ankle angular motion.Narrow stance width increased ankle angular motion, hip angular motion, mediolateral sway of the COG, and the correlation between linear motions of the shoulder and knee in the frontal plane. Correlations between COG and COP and linear motions of the shoulder and knee in the sagittal plane were decreased. The correlation between the hip angular sway in the sagittal and frontal planes was dependent on interaction between support and vision.Low, significant positive correlations with time lags of the maximum of cross-correlation of 250-300 ms were found between the EMG activity of the lateral gastrocnemius muscle and anteroposterior motions of the COG and COP during normal stance. Narrow stance width decreased both correlations whereas absence of vision increased the correlation with COP.Ankle mechanisms dominate during normal stance especially in the sagittal plane. Narrow stance width decreased the role of the ankle and increased the role of hip mechanisms in the sagittal plane, while in the frontal plane both increased.The modulation pattern of the lateral gastrocnemius muscle suggests a central program of control of the ankle joint stiffness working to predict the loading pattern. PMID:9882761

Comparison of tibiofemoral joint space width measurements from standing CT and fixed flexion radiography.

PubMed

Segal, Neil A; Frick, Eric; Duryea, Jeffrey; Nevitt, Michael C; Niu, Jingbo; Torner, James C; Felson, David T; Anderson, Donald D

2017-07-01

The objective of this project was to determine the relationship between medial tibiofemoral joint space width measured on fixed-flexion radiographs and the three-dimensional joint space width distribution on low-dose, standing CT (SCT) imaging. At the 84-month visit of the Multicenter Osteoarthritis Study, 20 participants were recruited. A commercial SCT scanner for the foot and ankle was modified to image knees while standing. Medial tibiofemoral joint space width was assessed on radiographs at fixed locations from 15% to 30% of compartment width using validated software and on SCT by mapping the distances between three-dimensional subchondral bone surfaces. Individual joint space width values from radiographs were compared with three-dimensional joint space width values from corresponding sagittal plane locations using paired t-tests and correlation coefficients. For the four medial-most tibiofemoral locations, radiographic joint space width values exceeded the minimal joint space width on SCT by a mean of 2.0 mm and were approximately equal to the 61st percentile value of the joint space width distribution at each respective sagittal-plane location. Correlation coefficients at these locations were 0.91-0.97 and the offsets between joint space width values from radiographs and SCT measurements were consistent. There were greater offsets and variability in the offsets between modalities closer to the tibial spine. Joint space width measurements on fixed-flexion radiographs are highly correlated with three-dimensional joint space width from SCT. In addition to avoiding bony overlap obscuring the joint, a limitation of radiographs, the current study supports a role for SCT in the evaluation of tibiofemoral OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1388-1395, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

An integrated hyperspectral and SAR satellite constellation for environment monitoring

NASA Astrophysics Data System (ADS)

Wang, Jinnian; Ren, Fuhu; Xie, Chou; An, Jun; Tong, Zhanbo

2017-09-01

A fully-integrated, Hyperspectral optical and SAR (Synthetic Aperture Radar) constellation of small earth observation satellites will be deployed over multiple launches from last December to next five years. The Constellation is expected to comprise a minimum of 16 satellites (8 SAR and 8 optical ) flying in two orbital planes, with each plane consisting of four satellite pairs, equally-spaced around the orbit plane. Each pair of satellites will consist of a hyperspectral/mutispectral optical satellite and a high-resolution SAR satellite (X-band) flying in tandem. The constellation is expected to offer a number of innovative capabilities for environment monitoring. As a pre-launch experiment, two hyperspectral earth observation minisatellites, Spark 01 and 02 were launched as secondary payloads together with Tansat in December 2016 on a CZ-2D rocket. The satellites feature a wide-range hyperspectral imager. The ground resolution is 50 m, covering spectral range from visible to near infrared (420 nm - 1000 nm) and a swath width of 100km. The imager has an average spectral resolution of 5 nm with 148 channels, and a single satellite could obtain hyperspectral imagery with 2.5 million km2 per day, for global coverage every 16 days. This paper describes the potential applications of constellation image in environment monitoring.

Finite Ground Coplanar (FGC) Waveguide: It's Characteristics and Advantages for Use in RF and Wireless Communication Circuits

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Katehi, Linda P. B.; Tentzeris, Emmanouil M.

1998-01-01

To solve many of the problems encountered when using conventional coplanar waveguide (CPW) with its semi-infinite ground planes, a new version of coplanar waveguide with electrically narrow ground planes has been developed. This new transmission line which we call Finite Ground Coplanar (FGC) waveguide has several advantages which make it a better transmission line for RF and wireless circuits. Since the ground planes are electrically narrow, spurious resonances created by the CPW ground planes and the metal carrier or package base are eliminated. In addition, lumped and distributed circuit elements may now be integrated into the ground strips in the same way as they traditionally have been integrated into the center conductor to realize novel circuit layouts that are smaller and have less parasitic reactance. Lastly, FGC is shown to have lower coupling between adjacent transmission lines than conventional CPW.

A Combined FEM/MoM/GTD Technique To Analyze Elliptically Polarized Cavity-Backed Antennas With Finite Ground Plane

NASA Technical Reports Server (NTRS)

Reddy, C. J.; Deshpande, M. D.; Fralick, D. T.; Cockrell, C. R.; Beck, F. B.

1996-01-01

Radiation pattern prediction analysis of elliptically polarized cavity-backed aperture antennas in a finite ground plane is performed using a combined Finite Element Method/Method of Moments/Geometrical Theory of Diffraction (FEM/MoM/GTD) technique. The magnetic current on the cavity-backed aperture in an infinite ground plane is calculated using the combined FEM/MoM analysis. GTD, including the slope diffraction contribution, is used to calculate the diffracted fields caused by both soft and hard polarizations at the edges of the finite ground plane. Explicit expressions for regular diffraction coefficients and slope diffraction coefficients are presented. The slope of the incident magnetic field at the diffraction points is derived and analytical expressions are presented. Numerical results for the radiation patterns of a cavity-backed circular spiral microstrip patch antenna excited by a coaxial probe in a finite rectangular ground plane are computed and compared with experimental results.

Cavity resonance absorption in ultra-high bandwidth CRT deflection structure by a resistive load

DOEpatents

Dunham, M.E.; Hudson, C.L.

1993-05-11

An improved ultra-high bandwidth helical coil deflection structure for a cathode ray tube is described comprising a first metal member having a bore therein, the metal walls of which form a first ground plane; a second metal member coaxially mounted in the bore of the first metal member and forming a second ground plane; a helical deflection coil coaxially mounted within the bore between the two ground planes; and a resistive load disposed in one end of the bore and electrically connected to the first and second ground planes, the resistive load having an impedance substantially equal to the characteristic impedance of the coaxial line formed by the two coaxial ground planes to inhibit cavity resonance in the structure within the ultra-high bandwidth of operation. Preferably, the resistive load comprises a carbon film on a surface of an end plug in one end of the bore.

Cavity resonance absorption in ultra-high bandwidth CRT deflection structure by a resistive load

DOEpatents

Dunham, Mark E.; Hudson, Charles L.

1993-01-01

An improved ultra-high bandwidth helical coil deflection structure for a hode ray tube is described comprising a first metal member having a bore therein, the metal walls of which form a first ground plane; a second metal member coaxially mounted in the bore of the first metal member and forming a second ground plane; a helical deflection coil coaxially mounted within the bore between the two ground planes; and a resistive load disposed in one end of the bore and electrically connected to the first and second ground planes, the resistive load having an impedance substantially equal to the characteristic impedance of the coaxial line formed by the two coaxial ground planes to inhibit cavity resonance in the structure within the ultra-high bandwidth of operation. Preferably, the resistive load comprises a carbon film on a surface of an end plug in one end of the bore.

A synthetic visual plane algorithm for visibility computation in consideration of accuracy and efficiency

NASA Astrophysics Data System (ADS)

Yu, Jieqing; Wu, Lixin; Hu, Qingsong; Yan, Zhigang; Zhang, Shaoliang

2017-12-01

Visibility computation is of great interest to location optimization, environmental planning, ecology, and tourism. Many algorithms have been developed for visibility computation. In this paper, we propose a novel method of visibility computation, called synthetic visual plane (SVP), to achieve better performance with respect to efficiency, accuracy, or both. The method uses a global horizon, which is a synthesis of line-of-sight information of all nearer points, to determine the visibility of a point, which makes it an accurate visibility method. We used discretization of horizon to gain a good performance in efficiency. After discretization, the accuracy and efficiency of SVP depends on the scale of discretization (i.e., zone width). The method is more accurate at smaller zone widths, but this requires a longer operating time. Users must strike a balance between accuracy and efficiency at their discretion. According to our experiments, SVP is less accurate but more efficient than R2 if the zone width is set to one grid. However, SVP becomes more accurate than R2 when the zone width is set to 1/24 grid, while it continues to perform as fast or faster than R2. Although SVP performs worse than reference plane and depth map with respect to efficiency, it is superior in accuracy to these other two algorithms.

The Effects of Ground Plane and Parasitic Layer on Linearly Tapered Slot Antenna

NASA Technical Reports Server (NTRS)

Lee, Richard Q.; Simons, Rainee N.

1996-01-01

The effects of a large ground plane and an upper parasitic layer on a linearly tapered slot antenna has been experimentally investigated. Results indicate that the presence of a large ground plane causes the beam to steer by as much as 50 deg from the endfire direction in the H-plane. With the addition of a parasitic layer above the fed antenna, further beam scanning can be achieved when the spacing between the fed and parasitic layers is properly chosen.

Study on conditional probability of surface rupture: effect of fault dip and width of seismogenic layer

NASA Astrophysics Data System (ADS)

Inoue, N.

2017-12-01

The conditional probability of surface ruptures is affected by various factors, such as shallow material properties, process of earthquakes, ground motions and so on. Toda (2013) pointed out difference of the conditional probability of strike and reverse fault by considering the fault dip and width of seismogenic layer. This study evaluated conditional probability of surface rupture based on following procedures. Fault geometry was determined from the randomly generated magnitude based on The Headquarters for Earthquake Research Promotion (2017) method. If the defined fault plane was not saturated in the assumed width of the seismogenic layer, the fault plane depth was randomly provided within the seismogenic layer. The logistic analysis was performed to two data sets: surface displacement calculated by dislocation methods (Wang et al., 2003) from the defined source fault, the depth of top of the defined source fault. The estimated conditional probability from surface displacement indicated higher probability of reverse faults than that of strike faults, and this result coincides to previous similar studies (i.e. Kagawa et al., 2004; Kataoka and Kusakabe, 2005). On the contrary, the probability estimated from the depth of the source fault indicated higher probability of thrust faults than that of strike and reverse faults, and this trend is similar to the conditional probability of PFDHA results (Youngs et al., 2003; Moss and Ross, 2011). The probability of combined simulated results of thrust and reverse also shows low probability. The worldwide compiled reverse fault data include low fault dip angle earthquake. On the other hand, in the case of Japanese reverse fault, there is possibility that the conditional probability of reverse faults with less low dip angle earthquake shows low probability and indicates similar probability of strike fault (i.e. Takao et al., 2013). In the future, numerical simulation by considering failure condition of surface by the source fault would be performed in order to examine the amount of the displacement and conditional probability quantitatively.

Vertical facial height and its correlation with facial width and depth: Three dimensional cone beam computed tomography evaluation based on dry skulls.

PubMed

Wang, Ming Feng; Otsuka, Takero; Akimoto, Susumu; Sato, Sadao

2013-01-01

The aim of the present study was to evaluate how vertical facial height correlates with mandibular plane angle, facial width and depth from a three dimensional (3D) viewing angle. In this study 3D cephalometric landmarks were identified and measurements from 43 randomly selected cone beam computed tomography (CBCT) images of dry skulls from the Weisbach collection of Vienna Natural History Museum were analyzed. Pearson correlation coefficients of facial height measurements and mandibular plane angle and the correlation coefficients of height-width and height-depth were calculated, respectively. The mandibular plane angle (MP-SN) significantly correlated with ramus height (Co-Go) and posterior facial height (PFH) but not with anterior lower face height (ALFH) or anterior total face height (ATFH). The ALFH and ATFH showed significant correlation with anterior cranial base length (S-N), whereas PFH showed significant correlation with the mandible (S-B) and maxilla (S-A) anteroposterior position. High or low mandibular plane angle might not necessarily be accompanied by long or short anterior face height, respectively. The PFH rather than AFH is assumed to play a key role in the vertical facial type whereas AFH seems to undergo relatively intrinsic growth.

Kinematic measurement from panned cinematography.

PubMed

Gervais, P; Bedingfield, E W; Wronko, C; Kollias, I; Marchiori, G; Kuntz, J; Way, N; Kuiper, D

1989-06-01

Traditional 2-D cinematography has used a stationary camera with its optical axis perpendicular to the plane of motion. This method has constrained the size of the object plane or has introduced potential errors from a small subject image size with large object field widths. The purpose of this study was to assess a panning technique that could overcome the inherent limitations of small object field widths, small object image sizes and limited movement samples. The proposed technique used a series of reference targets in the object field that provided the necessary scales and origin translations. A 102 m object field was panned. Comparisons between criterion distances and film measured distances for field widths of 46 m and 22 m resulted in absolute mean differences that were comparable to that of the traditional method.

A New Selective Area Lateral Epitaxy Approach for Depositing a-Plane GaN over r-Plane Sapphire

NASA Astrophysics Data System (ADS)

Chen, Changqing; Zhang, Jianping; Yang, Jinwei; Adivarahan, Vinod; Rai, Shiva; Wu, Shuai; Wang, Hongmei; Sun, Wenhong; Su, Ming; Gong, Zheng; Kuokstis, Edmundas; Gaevski, Mikhail; Khan, Muhammad Asif

2003-07-01

We report a new epitaxy procedure for growing extremely low defect density a-plane GaN films over r-plane sapphire. By combining selective area growth through a SiO2 mask opening to produce high height to width aspect ratio a-plane GaN pillars and lateral epitaxy from their c-plane facets, we obtained fully coalesced a-plane GaN films. The excellent structural, optical and electrical characteristics of these selective area lateral epitaxy (SALE) deposited films make them ideal for high efficiency III-N electronic and optoelectronic devices.

Influence of strike object grounding on close lightning electric fields

NASA Astrophysics Data System (ADS)

Baba, Yoshihiro; Rakov, Vladimir A.

2008-06-01

Using the finite difference time domain (FDTD) method, we have calculated vertical electric field Ez, horizontal (radial) electric field Eh, and azimuthal magnetic field Hϕ produced on the ground surface by lightning strikes to 160-m- and a 553-m-high conical strike objects representing the Peissenberg tower (Germany) and the CN Tower (Canada), respectively. The fields were computed for a typical subsequent stroke at distances d' from the bottom of the object ranging from 5 to 100 m for the 160-m tower and from 10 to 300 m for the 553-m tower. Grounding of the 160-m object was assumed to be accomplished by its underground basement represented by a 10-m-radius and 8-m-long perfectly conducting cylinder with or without a reference ground plane located 2 m below. The reference ground plane simulates, to some extent, a higher-conducting ground layer that is expected to exist below the water table. The configuration without reference ground plane actually means that this plane is present, but is located at an infinitely large depth. Grounding of the 553-m object was modeled in a similar manner but in the absence of reference ground plane only. In all cases considered, waveforms of Eh and Hϕ are not much influenced by the presence of strike object, while waveforms of Ez are. Waveforms of Ez are essentially unipolar (as they are in the absence of strike object) when the ground conductivity σ is 10 mS/m (the equivalent transient grounding impedance is several ohms) or greater. Thus, for the CN Tower, for which σ ≥ 10 mS/m, the occurrence of Ez polarity change is highly unlikely. For the 160-m tower and for σ = 1 and 0.1 mS/m, waveforms of Ez become bipolar (exhibit polarity change) at d' ≤ 10 m and d' ≤ 50 m, respectively, regardless of the presence of the reference ground plane. The corresponding equivalent transient grounding impedances are about 30 and 50 Ω in the absence of the reference ground plane and smaller than 10 Ω in the presence of the reference ground plane. The source of opposite polarity Ez is the potential rise at the object base (at the air/ground interface) relative to the reference ground plane. For a given grounding electrode geometry, the strength of this source increases with decreasing σ, provided that the grounding impedance is linear. Potential rises at the strike object base for σ = 1 and 0.1 mS/m are some hundreds of kilovolts, which is sufficient to produce electrical breakdown from relatively sharp edges of the basement over a distance of several meters (or more) along the ground surface. The resultant ground surface arcs will serve to reduce the equivalent grounding impedance and, hence, potential rise. Therefore, the polarity change of Ez near the Peissenberg tower, for which σ is probably about 1 mS/m, should be a rare phenomenon, if it occurs at all. The equivalent transient grounding impedance of the cylindrical basement is similar to that of a hemispherical grounding electrode of the same radius. For the 160-m tower and for hemispherical grounding electrode, the transient grounding impedance is higher than its dc grounding resistance for σ = 10 and 1 mS/m, but lower for σ = 0.1 mS/m. For the 553-m tower, the transient grounding impedance of hemispherical electrode is equal to or larger than its dc resistance for all values of σ considered.

Flow field in the wake of a bluff body driven through a steady recirculating flow

NASA Astrophysics Data System (ADS)

Poussou, Stephane B.; Plesniak, Michael W.

2015-02-01

The wake produced by a bluff body driven through a steady recirculating flow is studied experimentally in a water facility using particle image velocimetry. The bluff body has a rectangular cross section of height, , and width, , such that the aspect ratio, AR = H/ D, is equal to 3. The motion of the bluff body is uniform and rectilinear, and corresponds to a Reynolds number based on width, Re D = 9,600. The recirculating flow is confined within a hemicylindrical enclosure and is generated by planar jets emanating from slots of width, , such that . Under these conditions, experiments are performed in a closed-loop facility that enables complete optical access to the near-wake. Velocity fields are obtained up to a distance of downstream of the moving body. Data include a selection of phase-averaged velocity fields representative of the wake for a baseline case (no recirculation) and an interaction case (with recirculation). Results indicate that the transient downwash flow typically observed in wakes behind finite bodies of small aspect ratio is significantly perturbed by the recirculating flow. The wake is displaced from the ground plane and exhibits a shorter recirculation zone downstream of the body. In summary, it was found that the interaction between a bluff body wake and a recirculating flow pattern alters profoundly the dynamics of the wake, which has implications on scalar transport in the wake.

Directional control of infrared antenna-coupled tunnel diodes.

PubMed

Slovick, Brian A; Bean, Jeffrey A; Krenz, Peter M; Boreman, Glenn D

2010-09-27

Directional control of received infrared radiation is demonstrated with a phased-array antenna connected by a coplanar strip transmission line to a metal-oxide-metal (MOM) tunnel diode. We implement a MOM diode to ensure that the measured response originates from the interference of infrared antenna currents at specific locations in the array. The reception angle of the antenna is altered by shifting the diode position along the transmission line connecting the antenna elements. By fabricating the devices on a quarter wave dielectric layer above a ground plane, narrow beam widths of 35° FWHM in power and reception angles of ± 50° are achieved with minimal side lobe contributions. Measured radiation patterns at 10.6 μm are substantiated by electromagnetic simulations as well as an analytic interference model.

National Program for Inspection of Non-Federal Dams. Westminster Reservoir Dam (MA 00639) MA 00639, Merrimack River Basin, Westminster, Massachusetts. Phase I Inspection Report.

DTIC Science & Technology

1980-06-01

lot Spooil 2 -.. * -*/ .. . *. . . . . . . , ,_- * j.... . . .\\ %" -* e DEPARTMENT OF THE ARMY 424 TRAPELO ROAD WALTHAM. MASSACHUSETTS 02254 REPLY TO...Feet .El Top .............El. Natural Ground ............. Width Top ........................................ Width of Botton ...nilllwa 4 t mg with M aw =bte wiatg All in good condition.- t -.L E*L. Top EI.Natural Ground Vidth Top________ Width of Borrom Upstream Slope Downstream

The finite ground plane effect on the microstrip antenna radiation patterns

NASA Technical Reports Server (NTRS)

Huang, J.

1983-01-01

The uniform geometrical theory of diffraction (GTD) is employed for calculating the edge diffracted fields from the finite ground plane of a microstrip antenna. The source field from the radiating patch is calculated by two different methods: the slot theory and the modal expansion theory. Many numerical and measured results are presented to demonstrate the accuracy of the calculations and the finite ground plane edge effect.

Decay widths of ground-state and excited {Xi}{sub b} baryons in a nonrelativistic quark model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Limphirat, Ayut; Thailand Center of Excellence in Physics; Department of Applied Physics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Nakhon Ratchasima 30000

Decay processes of ground and excited bottom baryons are studied in the {sup 3}P{sub 0} nonrelativistic quark model with all model parameters fixed in the sector of light quarks. Using as an input the recent mass of {Xi}{sub b} and the theoretical masses of {Xi}{sub b}{sup *} and {Xi}{sub b}{sup '}, narrow decay widths are predicted for the ground-state bottom baryons {Xi}{sub b}{sup *} and {Xi}{sub b}{sup '}. The work predicts large decay widths, about 100 MeV for the {rho}-type orbital excitation states of {Xi}{sub b}.

Fabrication of interface-modified ramp-edge junction on YBCO ground plane with multilayer structure

NASA Astrophysics Data System (ADS)

Wakana, H.; Adachi, S.; Kamitani, A.; Sugiyama, H.; Sugano, T.; Horibe, M.; Ishimaru, Y.; Tarutani, Y.; Tanabe, K.

2003-10-01

We examined the fabrication conditions to obtain high-quality ramp-edge Josephson junctions on a liquid-phase-epitaxy YBa 2Cu 3O y (LPE-YBCO) ground plane, in particular, focusing on the fabrication of a suitable insulating layer on the ground plane and the post-annealing conditions to load oxygen to the ground plane. A (LaAlO 3) 0.3-(SrAl 0.5Ta 0.5O 3) 0.7 (LSAT) insulating film on the ground planes exhibited a conductance ranging from 10 -4 to 10 -8 S after deposition of an upper superconducting film, suggesting existence of some leak paths through the LSAT insulating layer. By introducing approximately 30 nm thick SrTiO 3 (STO) buffer layers on both side of the LSAT insulating layer. We reproducibly obtained a conductance lower than 10 -8 S. The dielectric constant of the STO/LSAT/STO layer was 32, which was slightly larger than that of the single LSAT layer. It was found that a very slow cooling rate of 1.0 °C/h in oxygen was needed to fully oxidize the ground plane through the STO/LSAT/STO insulating layers, while the oxidation time could be effectively reduced by introducing via holes in the insulating layer at an interval of 200 μm. Ramp-edge junctions on LPE-YBCO ground planes with STO/LSAT/STO insulating layers exhibited a 1 σ-spread in Ic of 8% for 100-junction series-arrays and a sheet inductance of 0.7 pH/□ at 4.2 K.

Heavy section fracture toughness screening specimen

NASA Technical Reports Server (NTRS)

Shannon, J. L., Jr.; Donald, J. K.; Brown, W. F., Jr.

1976-01-01

Size requirements for a pin loaded double edge notch + crack tension specimen proposed for fracture toughness screening heavy section alloys were studied. Ranking of eight selected alloys based on the specimen's net strength was compared with that based on the valid plane strain fracture toughness separately determined. Performance of the specimen was judged on the basis of that comparison. The specimen's net strength was influenced by three critical specimen dimensions: distance between the crack plane and the loading hole, specimen width, and specimen thickness. Interaction between the stress fields of the crack and the loading holes reduced the net strength, but this effect disappeared as the separation reached a dimension equal to the specimen width. The effects of specimen width and thickness are interrelated and affect the net strength through their influence on the development of the crack tip plastic zone.

Stress distribution in and equivalent width of flanges of wide, thin-wall steel beams

NASA Technical Reports Server (NTRS)

Winter, George

1940-01-01

The use of different forms of wide-flange, thin-wall steel beams is becoming increasingly widespread. Part of the information necessary for a national design of such members is the knowledge of the stress distribution in and the equivalent width of the flanges of such beams. This problem is analyzed in this paper on the basis of the theory of plane stress. As a result, tables and curves are given from which the equivalent width of any given beam can be read directly for use in practical design. An investigation is given of the limitations of this analysis due to the fact that extremely wide and thin flanges tend to curve out of their plane toward the neutral axis. A summary of test data confirms very satisfactorily the analytical results.

Vortex-Core Reversal Dynamics: Towards Vortex Random Access Memory

NASA Astrophysics Data System (ADS)

Kim, Sang-Koog

2011-03-01

An energy-efficient, ultrahigh-density, ultrafast, and nonvolatile solid-state universal memory is a long-held dream in the field of information-storage technology. The magnetic random access memory (MRAM) along with a spin-transfer-torque switching mechanism is a strong candidate-means of realizing that dream, given its nonvolatility, infinite endurance, and fast random access. Magnetic vortices in patterned soft magnetic dots promise ground-breaking applications in information-storage devices, owing to the very stable twofold ground states of either their upward or downward core magnetization orientation and plausible core switching by in-plane alternating magnetic fields or spin-polarized currents. However, two technologically most important but very challenging issues --- low-power recording and reliable selection of each memory cell with already existing cross-point architectures --- have not yet been resolved for the basic operations in information storage, that is, writing (recording) and readout. Here, we experimentally demonstrate a magnetic vortex random access memory (VRAM) in the basic cross-point architecture. This unique VRAM offers reliable cell selection and low-power-consumption control of switching of out-of-plane core magnetizations using specially designed rotating magnetic fields generated by two orthogonal and unipolar Gaussian-pulse currents along with optimized pulse width and time delay. Our achievement of a new device based on a new material, that is, a medium composed of patterned vortex-state disks, together with the new physics on ultrafast vortex-core switching dynamics, can stimulate further fruitful research on MRAMs that are based on vortex-state dot arrays.

16 CFR 1512.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS... post center line (or the center of the seating area if no seat post exists) and the ground plane, as measured with the wheels aligned and in a plane normal to the ground plane. (d) Track bicycle means a...

Transverse Stress Decay in a Specially Orthotropic Strip Under Localizing Normal Edge Loading

NASA Technical Reports Server (NTRS)

Fichter, W. B.

2000-01-01

Solutions are presented for the stresses in a specially orthotropic infinite strip which is subjected to localized uniform normal loading on one edge while the other edge is either restrained against normal displacement only, or completely fixed. The solutions are used to investigate the diffusion of load into the strip and in particular the decay of normal stress across the width of the strip. For orthotropic strips representative of a broad range of balanced and symmetric angle-ply composite laminates, minimum strip widths are found that ensure at least 90% decay of the normal stress across the strip. In addition, in a few cases where, on the fixed edge the peak shear stress exceeds the normal stress in magnitude, minimum strip widths that ensure 90% decay of both stresses are found. To help in putting these results into perspective, and to illustrate the influence of material properties on load 9 orthotropic materials, closed-form solutions for the stresses in similarly loaded orthotropic half-planes are obtained. These solutions are used to generate illustrative stress contour plots for several representative laminates. Among the laminates, those composed of intermediate-angle plies, i.e., from about 30 degrees to 60 degrees, exhibit marked changes in normal stress contour shape with stress level. The stress contours are also used to find 90% decay distances in the half-planes. In all cases, the minimum strip widths for 90% decay of the normal stress exceed the 90% decay distances in the corresponding half-planes, in amounts ranging from only a few percent to about 50% of the half-plane decay distances. The 90% decay distances depend on both material properties and the boundary conditions on the supported edge.

Large-eddy simulation of pollutant dispersion from a ground-level area source over urban street canyons with irreversible chemical reactions

NASA Astrophysics Data System (ADS)

Du, T. Z.; Liu, C.-H.; Zhao, Y. B.

2014-10-01

In this study, the dispersion of chemically reactive pollutants is calculated by large-eddy simulation (LES) in a neutrally stratified urban canopy layer (UCL) over urban areas. As a pilot attempt, idealized street canyons of unity building-height-to-street-width (aspect) ratio are used. Nitric oxide (NO) is emitted from the ground surface of the first street canyon into the domain doped with ozone (O3). In the absence of ultraviolet radiation, this irreversible chemistry produces nitrogen dioxide (NO2), developing a reactive plume over the rough urban surface. A range of timescales of turbulence and chemistry are utilized to examine the mechanism of turbulent mixing and chemical reactions in the UCL. The Damköhler number (Da) and the reaction rate (r) are analyzed along the vertical direction on the plane normal to the prevailing flow at 10 m after the source. The maximum reaction rate peaks at an elevation where Damköhler number Da is equal or close to unity. Hence, comparable timescales of turbulence and reaction could enhance the chemical reactions in the plume.

Measured Aerodynamic Interaction of Two Tiltrotors

NASA Technical Reports Server (NTRS)

Yamauchi, Gloria K.; Wadcock, Alan J.; Derby, Michael R.

2003-01-01

The aerodynamic interaction of two model tilrotors in helicopter-mode formation flight is investigated. Three cenarios representing tandem level flight, tandem operations near the ground, and a single tiltrotor operating above thc ground for varying winds are examined. The effect of aircraft separation distance on the thrust and rolling moment of the trailing aircraft with and without the presence of a ground plane are quantified. Without a ground plane, the downwind aircraft experiences a peak rolling moment when the right (left) roto- of the upwind aircraft is laterally aligned with the left (right) rotor of the downwind aircraft. The presence of the ground plane causes the peak rolling moment on the downwind aircraft to occur when the upwind aircraft is further outboard of the downwind aircraft. Ground plane surface flow visualization images obtained using rufts and oil are used to understand mutual interaction between the two aircraft. These data provide guidance in determining tiltrotor flight formations which minimize disturbance to the trailing aircraft.

RCS tests utilize ground-plane effects

NASA Astrophysics Data System (ADS)

Knott, E. F.

1984-03-01

It is noted that the ground effects must be thoroughly understood to attain the proper radar cross section (RCS) configurations for a specific test. If the ground is sufficiently smooth, it acts as a mirror. Ground reflections then serve to enhance the incident field strength. If an asphalt or concrete ground plane has not been constructed, the soil must be kept free of vegetation and must be graded and leveled to exploit the effect. To elucidate the role of the ground plane, the various ways that energy propagates to the target and back are considered. In implementing a ground-plane RCS measurement program, it is important that the target height, antenna height, target range, and radar wavelength be chosen so as to place the target at a peak in the interference pattern. It is pointed out that in order to maximize the received signal, the antenna should be depressed below the bisector of the angle between the direct and indirect paths subtended at the radar receiving antenna. The precise amount of depression depends on the antenna radiation pattern.

Preliminary observations of the effect of solutal convection on crystal morphology

NASA Technical Reports Server (NTRS)

Broom, M. Beth H.; Witherow, William K.; Snyder, Robert S.; Carter, Daniel C.

1988-01-01

Studies to examine the effect of solutal convection on crystal morphology using sucrose as a model system were initiated. Aspect ratios, defined as the width of the 100-plane-oriented face over the width of the 001-plane-oriented face, were determined for oriented crystals which were grown with either the 001-oriented or the 100-oriented face perpendicular to the convective flow. The dependence of the crystal morphology on orientation is much greater for crystals grown with one face occluded than for crystals grown suspended in solution. Many factors appear to interact in a complex fashion to influence crystal morphology.

Calculation of the effects of ice on the backscatter of a ground plane

NASA Technical Reports Server (NTRS)

Lambert, K. M.; Peters, L., Jr.

1988-01-01

Described is a technique for examining the effect of a rough ice layer on the backscatter of a ground plane. The technique is applied to the special case of a rough ice layer that is periodic in space. By assuming that the roughness is periodic, the backscatter of the ground plane can be found from the backscatter of a single period. Backscatter calculations are presented for a single period in which the thickness of the ice layer has a Gaussian shape.

An X-band parabolic antenna based on gradient metasurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Wang; Yang, Helin, E-mail: emyang@mail.ccnu.edu.cn; Tian, Ying

We present a novel parabolic antenna by employing reflection gradient metasurface which is composed of a series of circle patches on a grounded dielectric substrate. Similar to the traditional parabolic antenna, the proposed antenna take the metasurface as a “parabolic reflector” and a patch antenna was placed at the focal point of the metasurface as a feed source, then the quasi-spherical wave emitted by the source is reflected and transformed to plane wave with high efficiency. Due to the focus effect of reflection, the beam width of the antenna has been decreased from 85.9° to 13° and the gain hasmore » been increased from 6.5 dB to 20.8 dB. Simulation and measurement results of both near and far-field plots demonstrate good focusing properties of the proposed parabolic antenna.« less

A superellipsoid-plane model for simulating foot-ground contact during human gait.

PubMed

Lopes, D S; Neptune, R R; Ambrósio, J A; Silva, M T

2016-01-01

Musculoskeletal models and forward dynamics simulations of human movement often include foot-ground interactions, with the foot-ground contact forces often determined using a constitutive model that depends on material properties and contact kinematics. When using soft constraints to model the foot-ground interactions, the kinematics of the minimum distance between the foot and planar ground needs to be computed. Due to their geometric simplicity, a considerable number of studies have used point-plane elements to represent these interacting bodies, but few studies have provided comparisons between point contact elements and other geometrically based analytical solutions. The objective of this work was to develop a more general-purpose superellipsoid-plane contact model that can be used to determine the three-dimensional foot-ground contact forces. As an example application, the model was used in a forward dynamics simulation of human walking. Simulation results and execution times were compared with a point-like viscoelastic contact model. Both models produced realistic ground reaction forces and kinematics with similar computational efficiency. However, solving the equations of motion with the surface contact model was found to be more efficient (~18% faster), and on average numerically ~37% less stiff. The superellipsoid-plane elements are also more versatile than point-like elements in that they allow for volumetric contact during three-dimensional motions (e.g. rotating, rolling, and sliding). In addition, the superellipsoid-plane element is geometrically accurate and easily integrated within multibody simulation code. These advantages make the use of superellipsoid-plane contact models in musculoskeletal simulations an appealing alternative to point-like elements.

Exploration of ground instability factor causing slumping and related dewatering in high methane-flux and gentle continental slope off Shimokita Peninsula, NE Japan

NASA Astrophysics Data System (ADS)

Morita, S.; Nakajima, T.; Goto, S.; Yamada, Y.; Kawamura, K.

2012-12-01

A great number of slump (submarine landslide) units have been identified by reflection seismic surveys performed off Shimokita Peninsula, NE Japan (Morita, et al., 2011). A 3-D seismic data revealed typical deformations caused by slumping and related dewatering in the Pliocene and upper formations. The slumping was generated primarily by layer-parallel slip in a very gentle (<1 degree) and flat continental slope. The size of slump units extends over 30 km in both width and slip direction in maximum. The slump units often exhibit an imbrication structure formed by repeated thrusting in the bottom layers, being mostly composed of the thrust blocks and little matrix. The dewatering structure is observed as widespread parallel dikes of which distribution is strongly dependent on the imbrication of the slump units. Slip planes of the slumps are traceable in seismic data because of the layer-parallel slip. The layers which correspond to the slip planes proved to be generally characterized as low-amplitude layers having some thickness, and some of the slip planes exhibit flattened features under the slump units of the imbrication structure accompanied by parallel dikes. This implies that excess fluid in the slip plane caused the lubrication to enhance the slumping and was drained through the parallel dikes during slumping. Some typical structures related to natural gas, e.g. enhanced reflection, gas chimney, have been identified in the seismic data. The shakedown cruise of D/V Chikyu in 2006 reported a recovery of gas hydrate in nearby area (Higuchi et al., 2009). A shallow sulfate-methane interface (SMI) of 3.5-12 mbsf has been reported in the survey area (Kotani et al., 2007). These features indicate that a high methane flux in the area is likely an important ground instability factor to cause the slumping and the dewatering phenomena. We recognize that the set of the slump units in the survey area is one of the most suitable targets to approach mechanism of submarine landslides so that we started exploring the feasibility of a scientific drilling in this survey area.

NUCLEAR REACTORS

DOEpatents

Long, E.; Ashby, J.W.

1958-09-16

ABS>A graphite moderator structure is presented for a nuclear reactor compriscd of an assembly of similarly orientated prismatic graphite blocks arranged on spaced longitudinal axes lying in common planes wherein the planes of the walls of the blocks are positioned so as to be twisted reintive to the planes of said axes so thatthe unlmpeded dtrect paths in direction wholly across the walls of the blocks are limited to the width of the blocks plus spacing between the blocks.

Location of Osteochondritis Dissecans Lesions of the Capitellum.

PubMed

Johnson, Christine C; Roberts, Susanne; Mintz, Douglas; Fabricant, Peter D; Hotchkiss, Robert N; Daluiski, Aaron

2018-04-17

The location of capitellar osteochondritis dissecans (OCD) lesions in the sagittal plane guides the surgical approach, and lesion location in the coronal plane influences surgical management. Although most lesions have been reported to occur between 4 o'clock and 4:30 (120° to 135° anterior to the humerus), some lesions are located elsewhere in the capitellum. The primary aim was to define the region of the capitellum affected by OCD lesions using a novel clock-face localization system. We reviewed 104 magnetic resonance imaging examinations diagnosing a nontraumatic capitellar OCD lesion. In the sagittal plane, lesion margins were recorded as degrees on the capitellum and converted into a clock-face format in which 0° corresponds to 12:00 with the forearm facing to the right. The 0° axis (12-o'clock axis) was defined as a line parallel to the anterior humeral line that intersects the capitellum center. The following coronal measurements were recorded: lesion width, capitellar width, and distance between the lateral capitellum and lateral lesion. Two independent observers took measurements. In the sagittal plane, average lesion location was 92° to 150° (3:04-5:00, clock face) and ranged from 52.1° to 249.5° (1:44-8:19, clock face). Average lesion dimensions were 10.7 mm (mediolateral width) and 5.2 mm (anteroposterior depth). Interrater reliability was high (intraclass correlation coefficient = 0.98). Using a magnetic resonance imaging-based clock-face localization system, we found that capitellar OCD lesions affect a broad region of the capitellum in the sagittal plane. The clock-face localization system allows for precise description of capitellar OCD lesion location, which may facilitate intraoperative decision and longitudinal monitoring. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Pool spacing in forest channels

Treesearch

David R. Montgomery; John M. Buffington; Richard D. Smith; Kevin M. Schmidt; George Pess

1995-01-01

Field surveys of stream channels in forested mountain drainage basins in southeast Alaska and Washington reveal that pool spacing depends on large woody debris (LWD) loading and channel type, slope, and width. Mean pool spacing in pool-riffle, plane-bed, and forced pool-riffle channels systematically decreases from greater than 13 channel widths per pool to less than 1...

X-ray diffraction study of A- plane non-polar InN epilayer grown by MOCVD

NASA Astrophysics Data System (ADS)

Moret, Matthieu; Briot, Olivier; Gil, Bernard

2015-03-01

Strong polarisation-induced electric fields in C-plane oriented nitrides semiconductor layers reduce the performance of devices. Eliminating the polarization fields can be achieved by growing nitrides along non polar direction. We have grown non polar A-plane oriented InN on R-plane (1‾102) nitridated sapphire substrate by MOCVD. We have studied the structural anisotropy observed in these layers by analyzing High Resolution XRay Diffraction rocking curve (RC) experiments as a function of the in-plane beam orientation. A-plane InN epilayer have a unique epitaxial relationship on R-Plane sapphire and show a strong structural anisotropy. Full width at half maximum (FWHM) of the InN(11‾20) XRD RC values are contained between 44 and 81 Arcmin. FWHM is smaller when the diffraction occurs along the [0001] and the largest FWHM values, of the (11‾20) RC, are obtained when the diffraction occurs along the [1‾100] in-plane direction. Atomic Force Microscopy imaging revealed morphologies with well organized crystallites. The grains are structured along a unique crystallographic orientation of InN, leading to larger domains in this direction. This structural anisotropy can be, in first approximation, attributed to the difference in the domain sizes observed. XRD reciprocal space mappings (RSM) were performed in asymmetrical configuration on (13‾40) and (2‾202) diffraction plane. RSM are measured with a beam orientation corresponding to a maximal and a minimal width of the (11‾20) Rocking curves, respectively. A simple theoretical model is exposed to interpret the RSM. We concluded that the dominant contribution to the anisotropy is due to the scattering coherence length anisotropy present in our samples.

Electronic properties of prismatic modifications of single-wall carbon nanotubes

NASA Astrophysics Data System (ADS)

Tomilin, O. B.; Muryumin, E. E.; Rodionova, E. V.; Ryskina, N. P.

2018-01-01

The article shows the possibility of target modifying the prismatic single-walled carbon nanotubes (SWCNTs) by regular chemisorption of fluorine atoms in the graphene surface. It is shown that the electronic properties of prismatic SWCNT modifications are determined by the interaction of π- and ρ(in-plane)-electron conjugation in the carbon-conjugated subsystems (tracks) formed in the faces. The contributions of π- and ρ(in-plane)-electron conjugation depend on the structural characteristics of the tracks. It was found that the minimum of degree deviation of the track from the plane of the prism face and the maximum of the track width ensure the maximum contribution of the π-electron conjugation, and the band gap of the prismatic modifications of the SWCNT tends to the band gap of the hydrocarbon analog of the carbon track. It is established that the maximum of degree deviation of the track from the plane of the prism face and the maximum of track width ensure the maximum contribution of the ρ(in-plane) electron interface, and the band gap of the prismatic modifications of the SWCNT tends to the band gap of the unmodified carbon nanotube. The calculation of the model systems has been carried out using an ab initio Hartree-Fock method in the 3-21G basis.

Numerical Approach for Goaf-Side Entry Layout and Yield Pillar Design in Fractured Ground Conditions

NASA Astrophysics Data System (ADS)

Jiang, Lishuai; Zhang, Peipeng; Chen, Lianjun; Hao, Zhen; Sainoki, Atsushi; Mitri, Hani S.; Wang, Qingbiao

2017-11-01

Entry driven along goaf-side (EDG), which is the development of an entry of the next longwall panel along the goaf-side and the isolation of the entry from the goaf with a small-width yield pillar, has been widely employed in China over the past several decades . The width of such a yield pillar has a crucial effect on EDG layout in terms of the ground control, isolation effect and resource recovery rate. Based on a case study, this paper presents an approach for evaluating, designing and optimizing EDG and yield pillar by considering the results from numerical simulations and field practice. To rigorously analyze the ground stability, the numerical study begins with the simulation of goaf-side stress and ground conditions. Four global models with identical conditions, except for the width of the yield pillar, are built, and the effect of pillar width on ground stability is investigated by comparing aspects of stress distribution, failure propagation, and displacement evolution during the entire service life of the entry. Based on simulation results, the isolation effect of the pillar acquired from field practice is also considered. The suggested optimal yield pillar design is validated using a field test in the same mine. Thus, the presented numerical approach provides references and can be utilized for the evaluation, design and optimization of EDG and yield pillars under similar geological and geotechnical circumstances.

Laser backscattered from partially convex targets of large sizes in random media for E-wave polarization.

PubMed

El-Ocla, Hosam

2006-08-01

The characteristics of a radar cross section (RCS) of partially convex targets with large sizes up to five wavelengths in free space and random media are studied. The nature of the incident wave is an important factor in remote sensing and radar detection applications. I investigate the effects of beam wave incidence on the performance of RCS, drawing on the method I used in a previous study on plane-wave incidence. A beam wave can be considered a plane wave if the target size is smaller than the beam width. Therefore, to have a beam wave with a limited spot on the target, the target size should be larger than the beam width (assuming E-wave incidence wave polarization. The effects of the target configuration, random medium parameters, and the beam width on the laser RCS and the enhancement in the radar cross section are numerically analyzed, resulting in the possibility of having some sort of control over radar detection using beam wave incidence.

Electric and magnetic superlattices in trilayer graphene

NASA Astrophysics Data System (ADS)

Uddin, Salah; Chan, K. S.

2016-01-01

The properties of one dimensional Kronig-Penney type of periodic electric and vector potential on ABC-trilayer graphene superlattices are investigated. The energy spectra obtained with periodic vector potentials shows the emergence of extra Dirac points in the energy spectrum with finite energies. For identical barrier and well widths, the original as well as the extra Dirac points are located in the ky = 0 plane. An asymmetry between the barrier and well widths causes a shift in the extra Dirac points away from the ky = 0 plane. Extra Dirac points having same electron hole crossing energy as that of the original Dirac point as well as finite energy Dirac points are generated in the energy spectrum when periodic electric potential is applied to the system. By applying electric and vector potential together, the symmetry of the energy spectrum about the Fermi level is broken. A tunable band gap is induced in the energy spectrum by applying both electric and vector potential simultaneously with different barrier and well widths.

Effect of the focal plane position on CO2 laser beam cutting of injection molded polycarbonate sheets

NASA Astrophysics Data System (ADS)

Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.

2016-11-01

In the present research, the effect of laser beam focal plane position (FPP) on the kerf quality of the polycarbonate laser cutting is investigated. Low power CO2 laser is used as the heat source of the cutting runs. In the experiments, FPP is varied from 0 to -4mm while other processing parameters (i.e. laser power, cutting speed and gas pressure) are considered constant. Upper and lower kerf width, kerf taper, upper heat affected zone and surface roughness of the kerf wall are also considered as the responses. Observations signified that reducing the position of the laser beam focal point from zero to - 3mm reduces the upper and lower kerf width. However reducing FPP below -3mm leads to an increase in the kerf width. Results also reveals that upper heat affected zone value reduces by reduction in FPP. Moreover the best kerf wall surface roughness occurred at FPP= -3mm.

Application of the Finite Element Method to Reveal the Causes of Loss of Planeness of Hot-Rolled Steel Sheets during Laser Cutting

NASA Astrophysics Data System (ADS)

Garber, E. A.; Bolobanova, N. L.; Trusov, K. A.

2018-01-01

A finite element technique is developed to simulate the stresses and the strains during strip flattening to reveal the causes of the cutting-assisted loss of planeness of hot-rolled steel sheets processed in roller levelers. The loss of planeness is found to be caused by a nonuniform distribution of the flattening-induced longitudinal tensile stresses over the strip thickness and width. The application of tensile forces to a strip in a roller leveler decreases this nonuniformity and prevents loss of planeness in cutting.

High throughput analysis of samples in flowing liquid

DOEpatents

Ambrose, W. Patrick; Grace, W. Kevin; Goodwin, Peter M.; Jett, James H.; Orden, Alan Van; Keller, Richard A.

2001-01-01

Apparatus and method enable imaging multiple fluorescent sample particles in a single flow channel. A flow channel defines a flow direction for samples in a flow stream and has a viewing plane perpendicular to the flow direction. A laser beam is formed as a ribbon having a width effective to cover the viewing plane. Imaging optics are arranged to view the viewing plane to form an image of the fluorescent sample particles in the flow stream, and a camera records the image formed by the imaging optics.

Ultra-wideband polarization insensitive UT-shaped metamaterial absorber

NASA Astrophysics Data System (ADS)

Karampour, Nasrollah; Nozhat, Najmeh

2017-05-01

In this paper, an ultra-wideband metamaterial absorber (MMA) with U and T shaped resonators has been proposed. The resonators and the ground plane consist of gold (Au) and titanium (Ti) layers. The resistive sheet effect of Ti layer and the resonance elements in the structure cause a broad absorption spectrum. The simulations are based on the finite element method (FEM) and the results show that the absorption of the proposed structure is more than 90% between 150 and 300 THz that is much larger than previous works. Moreover, by applying the interference theory, we have demonstrated that the simulation results are in good agreement with the theoretical results. The primary proposed MMA is polarization sensitive. Therefore, a polarization insensitive metamaterial absorber has been suggested. Also, because of the extra resonance elements the full width at 90% absorption increases about 35 THz. This ultra-wideband MMA has various applications in microbalometer, imaging, thermal emitters, photovoltaic, and energy harvesting.

Influence of fracture anisotropy on ground water ages and chemistry, Valley and Ridge province, Pennsylvania

USGS Publications Warehouse

Burton, W.C.; Plummer, Niel; Busenberg, E.; Lindsey, B.D.; Gburek, W.J.

2002-01-01

Model ground water ages based on chlorofluorocarbons (CFCs) and tritium/helium-3 (3H/3He) data were obtained from two arrays of nested piezometers located on the north limb of an anticline in fractured sedimentary rocks in the Valley and Ridge geologic province of Pennsylvania. The fracture geometry of the gently east plunging fold is very regular and consists predominately of south dipping to subhorizontal to north dipping bedding-plane parting and east striking, steeply dipping axial-plane spaced cleavage. In the area of the piezometer arrays, which trend north-south on the north limb of the fold, north dipping bedding-plane parting is a more dominant fracture set than is steeply south dipping axial-plane cleavage. The dating of ground water from the piezometer arrays reveals that ground water traveling along paths parallel to the dip direction of bedding-plane parting has younger 3H/3He and CFC model ages, or a greater component of young water, than does ground water traveling along paths opposite to the dip direction. In predominantly unmixed samples there is a strong positive correlation between age of the young fraction of water and dissolved sodium concentration. The travel times inferred from the model ages are significantly longer than those previously calculated by a ground water flow model, which assumed isotropically fractured layers parallel to topography. A revised model factors in the directional anisotropy to produce longer travel times. Ground water travel times in the watershed therefore appear to be more influenced by anisotropic fracture geometry than previously realized. This could have significant implications for ground water models in other areas underlain by similarly tilted or folded sedimentary rock, such as elsewhere in the Valley and Ridge or the early Mesozoic basins.

High Frequency Magnetic Field Direction Finding Using MGL-S9A B-dot Sensors

DTIC Science & Technology

2013-03-21

relationship for incident plane wave on a linear array . . . . . . . . . . . 26 3.1 B-dot sensor design in CST Microwave Studio...CST Microwave Studio with an infinite PEC ground plane. . . . . . . . . . . . . . . 50 4.2 Radiation pattern of a single B-dot sensor at 32 MHz...simulated in CST Microwave Studio with an infinite PEC ground plane. . . . . . . . . . . . . . . 50 4.3 Radiation efficiency of single loop versus B-dot

Noise suppression due to annulus shaping of conventional coaxial nozzle

NASA Technical Reports Server (NTRS)

Vonglahn, U.; Goodykoontz, J.

1980-01-01

A method which shows that increasing the annulus width of a conventional coaxial nozzle with constant bypass velocity will lower the noise level is described. The method entails modifying a concentric coaxial nozzle to provide an eccentric outer stream annulus while maintaining approximately the same through flow as that for the original concentric bypass nozzle. Acoustical tests to determine the noise generating characteristics of the nozzle over a range of flow conditions are described. The tests involved sequentially analyzing the noise signals and digitally recording the 1/3 octave band sound pressure levels. The measurements were made in a plane passing through the minimum and maximum annulus width points, as well as at 90 degrees in this plane, by rotating the outer nozzle about its axis. Representative measured spectral data in the flyover plane for the concentric nozzle obtained at model scale are discussed. Representative spectra for several engine cycles are presented for both the eccentric and concentric nozzles at engine size.

Ground Impingement of a Fan Jet Exhaust Plume

DTIC Science & Technology

1978-05-01

ground plane to avoid a possible interaction between the ground-deflected exhaust and the fan j .t engine inlet. Two pitot pressure rakes , shown on the...Pressure signals from the two rakes (total of 18 pitot tubes) were read sequentially with a Scannivalve system, time-averaged, and displayed on a pen...taken from the inner anid outer rakes with the ground plane normal to the flow at h/d f 2. Pitot pressures from each rake were normalized by the

Carpet cloak with graded dielectric metasurface (Presentation Recording)

NASA Astrophysics Data System (ADS)

Hsu, LiYi; Lepetit, Thomas; Kante, Boubacar

2015-09-01

We demonstrate a method to hide a Gaussian-shaped bump on a ground plane from an incoming plane wave. In essence, we use a graded metasurface to shape the wavefronts like those of a flat ground plane[1,2].The metasurface provides additional phase to the electromagnetic field to control the reflection angle. To mimic a flat ground plane, the reflection angle is chosen to be equal to the incident angle. The desired phase distribution is calculated based on generalized Snell's laws[3]. We design our metasurface in the microwave range using sub-wavelength dielectric resonators. We verify the design by full-wave time-domain simulations and show that the result matches our theory well. This approach can be applied to hide any object on a ground plane not only at microwave frequencies but also at higher frequencies up to the infrared. 1. Jensen Li and J. B. Pendry, Hiding under the Carpet: A New Strategy for Cloaking. Phys. Rev. Lett. 101, 203901 (2008) 2. Andrea Alu, Mantle cloak: Invisibility induced by a surface. Phys. Rev. B 80, 245115 (2009) 3. Yu N, et al. Light propagation with phase discontinuities: Generalized laws of reflection and refraction. Science 334(6054):333-337 (2011)

Placement insensitive antenna for RFID, sensing, and/or communication systems

DOEpatents

Bernhard, Jennifer T.; Ruyle, Jessica E.

2014-06-10

An antenna includes a ground plane having a slot. The slot may be miniaturized using a meandered slot structure or other appropriate reactive loading method as an end load to one or both ends of the slot. An edge treatment may be included on one or more edges of the ground plane or a closely spaced reflecting plane. The antenna is structured to transmit or receive a signal independently or in response to electromagnetic radiation.

Magnetostriction-driven ground-state stabilization in 2H perovskites

DOE PAGES

Porter, D. G.; Senn, M. S.; Khalyavin, D. D.; ...

2016-10-04

In this paper, the magnetic ground state of Sr 3ARuO 6, with A =(Li,Na), is studied using neutron diffraction, resonant x-ray scattering, and laboratory characterization measurements of high-quality crystals. Combining these results allows us to observe the onset of long-range magnetic order and distinguish the symmetrically allowed magnetic models, identifying in-plane antiferromagnetic moments and a small ferromagnetic component along the c axis. While the existence of magnetic domains masks the particular in-plane direction of the moments, it has been possible to elucidate the ground state using symmetry considerations. We find that due to the lack of local anisotropy, antisymmetric exchangemore » interactions control the magnetic order, first through structural distortions that couple to in-plane antiferromagnetic moments and second through a high-order magnetoelastic coupling that lifts the degeneracy of the in-plane moments. Finally, the symmetry considerations used to rationalize the magnetic ground state are very general and will apply to many systems in this family, such as Ca 3ARuO 6, with A = (Li,Na), and Ca 3LiOsO 6 whose magnetic ground states are still not completely understood.« less

Theoretical study for aerial image intensity in resist in high numerical aperture projection optics and experimental verification with one-dimensional patterns

NASA Astrophysics Data System (ADS)

Shibuya, Masato; Takada, Akira; Nakashima, Toshiharu

2016-04-01

In optical lithography, high-performance exposure tools are indispensable to obtain not only fine patterns but also preciseness in pattern width. Since an accurate theoretical method is necessary to predict these values, some pioneer and valuable studies have been proposed. However, there might be some ambiguity or lack of consensus regarding the treatment of diffraction by object, incoming inclination factor onto image plane in scalar imaging theory, and paradoxical phenomenon of the inclined entrance plane wave onto image in vector imaging theory. We have reconsidered imaging theory in detail and also phenomenologically resolved the paradox. By comparing theoretical aerial image intensity with experimental pattern width for one-dimensional pattern, we have validated our theoretical consideration.

Erratum: ``CO Line Width Differences in Early Universe Molecular Emission-Line Galaxies: Submillimeter Galaxies versus QSO Hosts'' (AJ, 131, 2763 [2006])

NASA Astrophysics Data System (ADS)

Carilli, C. L.; Wang, Ran

2006-11-01

It has been pointed out to us that in three dimensions the mean angle of randomly oriented disks with respect to the sky plane is <θ>=30deg, and not the 45° assumed in the original paper. This lower angle for the (assumed) random distribution of submillimeter galaxies, coupled with the factor of 2.3 lower mean CO line width for high-z, far-IR-luminous QSO host galaxies relative to the submillimeter galaxies, implies a mean angle with respect to the sky plane for the QSO host galaxies of <θ>QSO=13deg, as opposed to the 18° quoted in the original paper. We thank Pat Hall for bringing this to our attention.

Three-dimensional analysis of the change in the curvature of the smiling line following orthodontic treatment in incisor class II division 1 malocclusion.

PubMed

Mah, Michael; Tan, Wei Chuan; Ong, Sim Heng; Chan, Yiong Huak; Foong, Kelvin

2014-12-01

To investigate the different effects of changes in the occlusal plane, incisors inclination, and maxillary intercanine width on the curvature of the smiling line. Records of 46 subjects (28 females and 18 males, mean age 16.6 ± 4.2 years) with incisor class II division 1 malocclusions were selected. All subjects had four premolar extractions and were treated with preadjusted edgewise appliances. Pre- and post-treatment maxillary dental digital models were virtually aligned via corresponding landmarks to the respective lateral cephalograms. Subsequent two-dimensional superimposition of the aligned cephalograms facilitated the three-dimensional superimposition of the pre- and post-treatment models. This process allowed the quantification of the curvature from a frontal perspective of the models. The change in curvature was then correlated with changes in the cephalometric inclination of the anterior occlusal plane (AOP), functional occlusal plane (FOP), maxillary central incisor (U1), and the intercanine width. Orthodontic correction in this sample resulted in the clockwise rotation of the anterior occlusal plane (5.84 degrees), reduction in proclination of the incisors (-14.39 degrees), increase in intercanine width (2.48mm), and a corresponding increase in the curvature of the smiling line (6.83 degrees). The change in curvature of the smiling line in these subjects was found to be related more significantly to the magnitude of difference in the inclination between the pre-treatment AOP and FOP than to the change in the inclination of the maxillary incisors. With orthodontic treatment, the smiling line can be correlated with cephalometric data to improve or maintain the curvature. © The Author 2013. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Effect of edge modification on the zigzag BC2N nanoribbons

NASA Astrophysics Data System (ADS)

Xiao, Xiang; Li, Hong; Tie, Jun; Lu, Jing

2016-08-01

We use first principles calculations to investigate the effects of edge modification with nonmetal species on zigzag-edged BC2N nanoribbons (ZBC2NNRs). These ZBC2NNRs show either semiconducting or metallic behaviors depending on the edge modifications and ribbon widths. We find that the O-modification induces a ferromagnetic ground state with a metallic behavior for all the ribbon widths investigated. And when the ribbon width is more than 3.32 nm (NZ ⩾ 16), an antiferromagnetic ground state with a half-metallic behavior is realized in the H-passivated ZBC2NNRs. These versatile electronic properties render the ZBC2NNRs a promising candidate material in nanoelectronics and nanospintronics.

SEDHI: a new generation of detection electronics for earth observation satellites

NASA Astrophysics Data System (ADS)

Dantes, Didier; Neveu, Claude; Biffi, Jean-Marc; Devilliers, Christophe; Andre, Serge

2017-11-01

Future earth observation optical systems will be more and more demanding in terms of ground sampling distance, swath width, number of spectral bands, duty cycle. Existing architectures of focal planes and video processing electronics are hardly compatible with these new requirements: electronic functions are split in several units, and video processing is limited to frequencies around 5 MHz in order to fulfil the radiometric requirements expected for high performance image quality systems. This frequency limitation induces a high number of video chains operated in parallel to process the huge amount of pixels at focal plane output, and leads to unacceptable mass and power consumption budgets. Furthermore, splitting the detection electronics functions into several units (at least one for the focal plane and proximity electronics, and one for the video processing functions) does not optimise the production costs : specific development efforts must be performed on critical analogue electronics at each equipment level and operations of assembly, integration and tests are duplicated at equipment and subsystem levels. Alcatel Space Industries has proposed to CNES a new concept of highly integrated detection electronics (SEDHI), and is developing for CNES a breadboard which will allow to confirm its potentialities. This paper presents the trade-off study which have been performed before selection of this new concept and summarises the main advantages and drawbacks of each possible architecture. The electrical, mechanical and thermal aspects of the SEDHI concept are described, including the basic technologies : ASIC for phase shift of detector clocks, ASIC for video processing, hybrids, microchip module... The adaptability to a large amount of missions and optical instruments is also discussed.

Canine sacroiliac luxation: anatomic study of the craniocaudal articular surface angulation of the sacrum to define a safe corridor in the dorsal plane for placement of screws used for fixation in lag fashion.

PubMed

Bowlt, Kelly L; Shales, Christopher J

2011-01-01

To define a safe corridor in the dorsal plane relative to the articular surface for placement of a single screw in lag fashion to achieve stabilization of sacroiliac luxation in the dog. Cadaveric study. Dorsoventral radiographs of denuded canine sacra (n=49) were taken to determine the safe corridor in the craniocaudal plane, and the maximum, optimum and minimum angles were calculated that would allow a screw inserted in lag fashion to engage at least 60% of the width of the sacral body without cranial or caudal penetration through the bone. The mean safe corridor in the dorsal plane is ∼24° wide. Mean craniocaudal minimum, optimum and maximum drill angles from the drill start point were 88°, 100°, and 111° from the articular surface, respectively. No single angle will completely avoid risk of screw penetration beyond the safe corridor cranially and caudally. There is sufficient anatomic variation between different canine sacra that a single angle cannot be recommended for screw placement in the dorsal plane. A standard angle cannot be recommended for screw placement in lag fashion within the canine sacrum in the dorsal plane. Because of the narrow width of the safe corridor, preoperative measurements on radiographs are recommended and a range of angled drill guides may be useful to decrease surgeon margin of error. © Copyright 2010 by The American College of Veterinary Surgeons.

Applying face identification to detecting hijacking of airplane

NASA Astrophysics Data System (ADS)

Luo, Xuanwen; Cheng, Qiang

2004-09-01

That terrorists hijacked the airplanes and crashed the World Trade Center is disaster to civilization. To avoid the happening of hijack is critical to homeland security. To report the hijacking in time, limit the terrorist to operate the plane if happened and land the plane to the nearest airport could be an efficient way to avoid the misery. Image processing technique in human face recognition or identification could be used for this task. Before the plane take off, the face images of pilots are input into a face identification system installed in the airplane. The camera in front of pilot seat keeps taking the pilot face image during the flight and comparing it with pre-input pilot face images. If a different face is detected, a warning signal is sent to ground automatically. At the same time, the automatic cruise system is started or the plane is controlled by the ground. The terrorists will have no control over the plane. The plane will be landed to a nearest or appropriate airport under the control of the ground or cruise system. This technique could also be used in automobile industry as an image key to avoid car stealth.

Space Particle Hazard Specification, Forecasting, and Mitigation

DTIC Science & Technology

2007-11-30

Automated FTP scripts permitted users to automatically update their global input parameter data set directly from the National Oceanic and...of CEASE capabilities. The angular field-of-view for CEASE is relatively large and will not allow for pitch angle resolved measurements. However... angular zones spanning 120° in the plane containing the magnetic field with an approximate 4° width in the direction perpendicular to the look-plane

Fracture analysis of ductile materials

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.

1980-01-01

In the present paper, Newman's (1973) two-parameter fracture criterion is used to analyze failure of single-edge-crack tension specimens made of bolting steel and rotor steel, with thicknesses and widths of the same order. It is shown that for width-to-thickness ratios of roughly unity, the plastic-collapse stress is strongly influenced by the state of stress on the net section and the collapse stress is closer to the plane-strain value.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bemporad, G.A.; Rubin, H.

This manuscript concerns the onset of thermohaline convection in a solar pond subject to field conditions as well as a small scale laboratory test section simulating the solar pond performance. The onset of thermohaline convection is analyzed in this study by means of a linear stability analysis in which the flow field perturbations are expended in sets of complete orthonormal functions satisfying the boundary conditions of the flow field. The linear stability analysis is first performed with regard to an advanced solar pond (ASP) subject to field conditions in which thermohaline convection develops in planes perpendicular to the unperturbed flowmore » velocity vector. In the laboratory simulator of the ASP the width and depth are of the same order of magnitude. In this case it is found that the side walls delay the onset of convection in planes perpendicular to the unperturbed flow velocity vector. The presence of the side walls may cause the planes parallel to the flow velocity to be the most susceptible to the development on all three spatial variables, are predicted. They may develop in planes parallel or perpendicular to the unperturbed velocity vector according to the value of the Reynolds number of the unperturbed flow and the ratio between the width and depth of the ASP simulator.« less

MAcro-Electro-Mechanical Systems (MÆMS) based concept for microwave beam steering in reflectarray antennas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Momeni Hasan Abadi, Seyed Mohamad Amin, E-mail: momenihasana@wisc.edu; Booske, John H., E-mail: jhbooske@wisc.edu; Behdad, Nader, E-mail: behdad@wisc.edu

2016-08-07

We present a new approach to perform beam steering in reflecting type apertures such as reflectarray antennas. The proposed technique exploits macro-scale mechanical movements of parts of the structure to achieve two-dimensional microwave beam steering without using any solid-state devices or phase shifters integrated within the aperture of the antenna. The principles of operation of this microwave beam steering technique are demonstrated in an aperture occupied by ground-plane-backed, sub-wavelength capacitive patches with identical dimensions. We demonstrate that by tilting the ground plane underneath the entire patch array layer, a phase shift gradient can be created over the aperture of themore » reflectarray that determines the direction of the radiated beam. Changing the direction and slope of this phase shift gradient on the aperture allows for performing beam steering in two dimensions using only one control parameter (i.e., tilt vector of the ground plane). A proof-of-concept prototype of the structure operating at X-band is designed, fabricated, and experimentally characterized. Experiments demonstrate that small mechanical movements of the ground plane (in the order of 0.05λ{sub 0}) can be used to steer the beam direction in the ±10° in two dimensions. It is also demonstrated that this beam scanning range can be greatly enhanced to ±30° by applying this concept to the same structure when its ground plane is segmented.« less

Discovery of a GeV blazar shining through the galactic plane

DOE PAGES

Vandenbroucke, J.; Buehler, R.; Ajello, M.; ...

2010-07-14

The Fermi Large Area Telescope (LAT) discovered a new gamma-ray source near the Galactic plane, Fermi J0109+6134, when it flared brightly in 2010 February. The low Galactic latitude (b = –1more » $$ο\\atop{.}$$2) indicated that the source could be located within the Galaxy, which motivated rapid multi-wavelength follow-up including radio, optical, and X-ray observations. Here, we report the results of analyzing all 19 months of LAT data for the source, and of X-ray observations with both Swift and the Chandra X-ray Observatory. We determined the source redshift, z = 0.783, using a Keck Low-Resolution Imaging Spectrometer observation. Finally, we compiled a broadband spectral energy distribution (SED) from both historical and new observations contemporaneous with the 2010 February flare. The redshift, SED, optical line width, X-ray absorption, and multi-band variability indicate that this new GeV source is a blazar seen through the Galactic plane. Because several of the optical emission lines have equivalent width >5 Å, this blazar belongs in the flat-spectrum radio quasar category.« less

Grounding the figure: surface attachment influences figure-ground organization.

PubMed

Vecera, Shaun P; Palmer, Stephen E

2006-08-01

We investigated whether the lower region effect on figure-ground organization (Vecera, Vogel, and Woodman, 2002) would generalize to contextual depth planes in vertical orientations, as is predicted by a theoretical analysis based on the ecological statistics of edges arising from objects that are attached to surfaces of support. Observers viewed left/right ambiguous figure-ground displays that occluded middle sections of four types of contextual inducers: two types of attached, receding, vertical planes (walls) that used linear perspective and/or texture gradients to induce perceived depth and two types of similar trapezoidal control figures that used either uniform color or random texture to reduce or eliminate perceived depth. The results showed a reliable bias toward seeing as "figure" the side of the figure-ground display that was attached to the receding depth plane, but no such bias for the corresponding side in either of the control conditions. The results are interpreted as being consistent with the attachment hypothesis that the lower region cue to figure-ground organization results from ecological biases in edge interpretation that arise when objects are attached to supporting surfaces in the terrestrial gravitational field.

Minimizing eddy currents induced in the ground plane of a large phased-array ultrasound applicator for echo-planar imaging-based MR thermometry.

PubMed

Lechner-Greite, Silke M; Hehn, Nicolas; Werner, Beat; Zadicario, Eyal; Tarasek, Matthew; Yeo, Desmond

2016-01-01

The study aims to investigate different ground plane segmentation designs of an ultrasound transducer to reduce gradient field induced eddy currents and the associated geometric distortion and temperature map errors in echo-planar imaging (EPI)-based MR thermometry in transcranial magnetic resonance (MR)-guided focused ultrasound (tcMRgFUS). Six different ground plane segmentations were considered and the efficacy of each in suppressing eddy currents was investigated in silico and in operando. For the latter case, the segmented ground planes were implemented in a transducer mockup model for validation. Robust spoiled gradient (SPGR) echo sequences and multi-shot EPI sequences were acquired. For each sequence and pattern, geometric distortions were quantified in the magnitude images and expressed in millimeters. Phase images were used for extracting the temperature maps on the basis of the temperature-dependent proton resonance frequency shift phenomenon. The means, standard deviations, and signal-to-noise ratios (SNRs) were extracted and contrasted with the geometric distortions of all patterns. The geometric distortion analysis and temperature map evaluations showed that more than one pattern could be considered the best-performing transducer. In the sagittal plane, the star (d) (3.46 ± 2.33 mm) and star-ring patterns (f) (2.72 ± 2.8 mm) showed smaller geometric distortions than the currently available seven-segment sheet (c) (5.54 ± 4.21 mm) and were both comparable to the reference scenario (a) (2.77 ± 2.24 mm). Contrasting these results with the temperature maps revealed that (d) performs as well as (a) in SPGR and EPI. We demonstrated that segmenting the transducer ground plane into a star pattern reduces eddy currents to a level wherein multi-plane EPI for accurate MR thermometry in tcMRgFUS is feasible.

Oriented graphene nanoribbons embedded in hexagonal boron nitride trenches

PubMed Central

Chen, Lingxiu; He, Li; Wang, Hui Shan; Wang, Haomin; Tang, Shujie; Cong, Chunxiao; Xie, Hong; Li, Lei; Xia, Hui; Li, Tianxin; Wu, Tianru; Zhang, Daoli; Deng, Lianwen; Yu, Ting; Xie, Xiaoming; Jiang, Mianheng

2017-01-01

Graphene nanoribbons (GNRs) are ultra-narrow strips of graphene that have the potential to be used in high-performance graphene-based semiconductor electronics. However, controlled growth of GNRs on dielectric substrates remains a challenge. Here, we report the successful growth of GNRs directly on hexagonal boron nitride substrates with smooth edges and controllable widths using chemical vapour deposition. The approach is based on a type of template growth that allows for the in-plane epitaxy of mono-layered GNRs in nano-trenches on hexagonal boron nitride with edges following a zigzag direction. The embedded GNR channels show excellent electronic properties, even at room temperature. Such in-plane hetero-integration of GNRs, which is compatible with integrated circuit processing, creates a gapped channel with a width of a few benzene rings, enabling the development of digital integrated circuitry based on GNRs. PMID:28276532

Aerodynamic braking of high speed ground transportation vehicles.

NASA Technical Reports Server (NTRS)

Marte, J. E.; Marko, W. J.

1973-01-01

The drag effectiveness of aerodynamic brakes arranged in series on a train-like vehicle was investigated. Fixed- and moving-model testing techniques were used in order to determine the importance of proper vehicle-ground interference simulation. Fixed-model tests were carried out on a sting-mounted model: alone; with a fixed ground plane; and in proximity to an image model. Moving-model tests were conducted in a vertical slide-wire facility with and without a ground plane. Results from investigations of one brake configuration are presented which show the effect of the number of brakes in the set and of spacing between brakes.

Plasmonic Surface Lattice Resonances: A Review of Properties and Applications.

PubMed

Kravets, V G; Kabashin, A V; Barnes, W L; Grigorenko, A N

2018-06-27

When metal nanoparticles are arranged in an ordered array, they may scatter light to produce diffracted waves. If one of the diffracted waves then propagates in the plane of the array, it may couple the localized plasmon resonances associated with individual nanoparticles together, leading to an exciting phenomenon, the drastic narrowing of plasmon resonances, down to 1-2 nm in spectral width. This presents a dramatic improvement compared to a typical single particle resonance line width of >80 nm. The very high quality factors of these diffractively coupled plasmon resonances, often referred to as plasmonic surface lattice resonances, and related effects have made this topic a very active and exciting field for fundamental research, and increasingly, these resonances have been investigated for their potential in the development of practical devices for communications, optoelectronics, photovoltaics, data storage, biosensing, and other applications. In the present review article, we describe the basic physical principles and properties of plasmonic surface lattice resonances: the width and quality of the resonances, singularities of the light phase, electric field enhancement, etc. We pay special attention to the conditions of their excitation in different experimental architectures by considering the following: in-plane and out-of-plane polarizations of the incident light, symmetric and asymmetric optical (refractive index) environments, the presence of substrate conductivity, and the presence of an active or magnetic medium. Finally, we review recent progress in applications of plasmonic surface lattice resonances in various fields.

Britle failure of non-Newtonian, floating, extensional flows

NASA Astrophysics Data System (ADS)

Sayag, Roiy; Worster, Michael

2011-11-01

Glacier ice is driven by gravity to flow from the land, where it is under shear, into the ocean, where it floats and extends. Owing to its non-Newtonian rheology, the ice can flow axisymmetrically over the bed but undergo brittle failure once it is floating on the ocean, as observed for example in crevassing of ice shelves. We model this coupled flow as an intrusion of a viscous gravity current into a denser ocean and study it both theoretically and experimentally. We have conducted laboratory experiments using a shear-thinning suspension that represents ice, and a denser inviscid fluid that represents an ocean. The non-Newtonian fluid was released at a constant flux through a cylindrical nozzle over a horizontal plane. The grounded, shear-dominated region of the flow was axisymmetric throughout the experiment, while past the transition line axisymmetry broke down into a seemingly ordered set of finger-like extensions (floating shelves) that demonstrated brittle behaviour. We have found that the width of the fingers as well as their radial extent increase with the flux. We attempt to explain these observations through a fingering instability that is driven by the dynamical differences between the two flow domains and by the material rheology, and we project that analysis to formulate a linkage between the material properties of ice and an upper bound on the width of ice shelves. NERC

Antenna structure with distributed strip

DOEpatents

Rodenbeck, Christopher T.

2008-10-21

An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

Antenna structure with distributed strip

DOEpatents

Rodenbeck, Christopher T [Albuquerque, NM

2008-03-18

An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

Enhanced backscattering through a deep random phase screen

NASA Astrophysics Data System (ADS)

Jakeman, E.

1988-10-01

The statistical properties of radiation scattered by a system consisting of a plane mirror placed in the Fresnel region behind a smoothly varying deep random-phase screen with off-axis beam illumination are studied. It is found that two mechanisms cause enhanced scattering around the backward direction, according to the mirror position with respect to the focusing plane of the screen. In all of the plane mirror geometries considered, the scattered field remains a complex Gaussian process with a spatial coherence function identical to that expected for a single screen, and a speckle size smaller than the width of backscatter enhancement.

High voltage variable diameter insulator

DOEpatents

Vanacek, D.L.; Pike, C.D.

1982-07-13

A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

The analysis on the relation between the compression method and the performance enhancement of MSC (Multi-Spectral Camera) image data

NASA Astrophysics Data System (ADS)

Yong, Sang-Soon; Ra, Sung-Woong

2007-10-01

Multi-Spectral Camera(MSC) is a main payload on the KOMPSAT-2 satellite to perform the earth remote sensing. The MSC instrument has one(1) channel for panchromatic imaging and four(4) channel for multi-spectral imaging covering the spectral range from 450nm to 900nm using TDI CCD Focal Plane Array (FPA). The instrument images the earth using a push-broom motion with a swath width of 15 km and a ground sample distance (GSD) of 1 m over the entire field of view (FOV) at altitude 685 Km. The instrument is designed to have an on-orbit operation duty cycle of 20% over the mission lifetime of 3 years with the functions of programmable gain/ offset and on-board image data compression/ storage. The compression method on KOMPSAT-2 MSC was selected and used to match EOS input rate and PDTS output data rate on MSC image data chain. At once the MSC performance was carefully handled to minimize any degradation so that it was analyzed and restored in KGS(KOMPSAT Ground Station) during LEOP and Cal./Val.(Calibration and Validation) phase. In this paper, on-orbit image data chain in MSC and image data processing on KGS including general MSC description is briefly described. The influences on image performance between on-board compression algorithms and between performance restoration methods in ground station are analyzed, and the relation between both methods is to be analyzed and discussed.

Evolution of strain localization in variable-width three-dimensional unsaturated laboratory-scale cut slopes

USGS Publications Warehouse

Morse, Michael S.; Lu, Ning; Wayllace, Alexandra; Godt, Jonathan W.

2017-01-01

To experimentally validate a recently developed theory for predicting the stability of cut slopes under unsaturated conditions, the authors measured increasing strain localization in unsaturated slope cuts prior to abrupt failure. Cut slope width and moisture content were controlled and varied in a laboratory, and a sliding door that extended the height of the free face of the slope was lowered until the cut slope failed. A particle image velocimetry tool was used to quantify soil displacement in the x-y">x-y (horizontal) and x-z">x-z (vertical) planes, and strain was calculated from the displacement. Areas of maximum strain localization prior to failure were shown to coincide with the location of the eventual failure plane. Experimental failure heights agreed with the recently developed stability theory for unsaturated cut slopes (within 14.3% relative error) for a range of saturation and cut slope widths. A theoretical threshold for sidewall influence on cut slope failures was also proposed to quantify the relationship between normalized sidewall width and critical height. The proposed relationship was consistent with the cut slope experiment results, and is intended for consideration in future geotechnical experiment design. The experimental data of evolution of strain localization presented herein provide a physical basis from which future numerical models of strain localization can be validated.

Finding the times that SMMR observed a ship

NASA Technical Reports Server (NTRS)

1979-01-01

In order to facilitate the coincidence calculations, the coordinates of the ship and the satellite were transformed to the ECO system in which the equatorial plane is the plane of the satellite's orbit. The transformation matrices for each step are presented. The ship could be observed when it was in a band about the equator in the ECO system. The width of the band was determined by the scan pattern of the instrument.

Propagation properties of cylindrical sinc Gaussian beam

NASA Astrophysics Data System (ADS)

Eyyuboğlu, Halil T.; Bayraktar, Mert

2016-09-01

We investigate the propagation properties of cylindrical sinc Gaussian beam in turbulent atmosphere. Since an analytic solution is hardly derivable, the study is carried out with the aid of random phase screens. Evolutions of the beam intensity profile, beam size and kurtosis parameter are analysed. It is found that on the source plane, cylindrical sinc Gaussian beam has a dark hollow appearance, where the side lobes also start to emerge with increase in width parameter and Gaussian source size. During propagation, beams with small width and Gaussian source size exhibit off-axis behaviour, losing the dark hollow shape, accumulating the intensity asymmetrically on one side, whereas those with large width and Gaussian source size retain dark hollow appearance even at long propagation distances. It is seen that the beams with large widths expand more in beam size than the ones with small widths. The structure constant values chosen do not seem to alter this situation. The kurtosis parameters of the beams having small widths are seen to be larger than the ones with the small widths. Again the choice of the structure constant does not change this trend.

Research study on multi-KW-DC distribution system

NASA Technical Reports Server (NTRS)

Berkery, E. A.; Krausz, A.

1975-01-01

A detailed definition of the HVDC test facility and the equipment required to implement the test program are provided. The basic elements of the test facility are illustrated, and consist of: the power source, conventional and digital supervision and control equipment, power distribution harness and simulated loads. The regulated dc power supplies provide steady-state power up to 36 KW at 120 VDC. Power for simulated line faults will be obtained from two banks of 90 ampere-hour lead-acid batteries. The relative merits of conventional and multiplexed power control will be demonstrated by the Supervision and Monitor Unit (SMU) and the Automatically Controlled Electrical Systems (ACES) hardware. The distribution harness is supported by a metal duct which is bonded to all component structures and functions as the system ground plane. The load banks contain passive resistance and reactance loads, solid state power controllers and active pulse width modulated loads. The HVDC test facility is designed to simulate a power distribution system for large aerospace vehicles.

Thermal Infrared Hot Spot and Dependence on Canopy Geometry

NASA Technical Reports Server (NTRS)

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

2001-01-01

We perform theoretical calculations of the canopy thermal infrared (TIR) hot spot using a first principles 3-D model described earlier. Various theoretical canopies of varying leaf size and for differing canopy height are used to illustrate the magnitude of the TIR effect. Our results are similar to predicted behavior in the reflective hot spot as a function of canopy geometry and comparable to TIR measurements from the literature and our own simple ground experiments. We apply the MODTRAN atmospheric code to estimate the at-sensor variation in brightness temperature with view direction in the solar principal plane. For simple homogeneous canopies, we predict canopy thermal infrared hot spot variations of 2 degrees C at the surface with respect to nadir viewing. Dependence on leaf size is weak as long as the ratio of leaf size to canopy height is maintained. However, the angular width of the hot spot increases as the ratio of leaf diameter to canopy height increases. Atmospheric effects minimize but do not eliminate the TIR hot spot at satellite altitudes.

Fast and reliable obstacle detection and segmentation for cross-country navigation

NASA Technical Reports Server (NTRS)

Talukder, A.; Manduchi, R.; Rankin, A.; Matthies, L.

2002-01-01

Obstacle detection is one of the main components of the control system of autonomous vehicles. In the case of indoor/urban navigation, obstacles are typically defined as surface points that are higher than the ground plane. This characterization, however, cannot be used in cross-country and unstructured environments, where the notion of ground plane is often not meaningful.

Miniaturized printed K shaped monopole antenna with truncated ground plane for 2.4/5.2/5.5/5.8 wireless lan applications

NASA Astrophysics Data System (ADS)

Chandan, Bharti, Gagandeep; Srivastava, Toolika; Rai, B. S.

2018-04-01

A novel truncated ground plane monopole antenna is proposed for wide band wireless local area network (WLAN) applications. The antenna contains a rectangular patch with a rectangular ring, a circular slot and a truncated ground plane printed on opposite sides of a low cost substrate FR4. The operating frequency bands for the antenna are band1 (2.4-2.88 GHz) and band 2 (4.8-6.3 GHz) with ≤ - 10 dB return loss which covers 2.4/5.2/5.5/5.8 GHz WLAN bands. The antenna is compact with overall dimension 26×40×0.8 mmł and with the dimension of patch 16×16×0.8 mm3. The two bands of antenna is obtained by cutting a rectangular ring and a circular slot in the patch and return loss is improved by cutting two rectangular slot in the ground plane. Performance measures of the antenna are shown in terms of return loss, current distribution, radiation pattern and gain. To verify the simulated results, the antenna is also fabricated and tested. The simulated and fabricated results have been found in good agreement.

High-quality nonpolar a-plane GaN epitaxial films grown on r-plane sapphire substrates by the combination of pulsed laser deposition and metal–organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Yang, Weijia; Zhang, Zichen; Wang, Wenliang; Zheng, Yulin; Wang, Haiyan; Li, Guoqiang

2018-05-01

High-quality a-plane GaN epitaxial films have been grown on r-plane sapphire substrates by the combination of pulsed laser deposition (PLD) and metal–organic chemical vapor deposition (MOCVD). PLD is employed to epitaxial growth of a-plane GaN templates on r-plane sapphire substrates, and then MOCVD is used. The nonpolar a-plane GaN epitaxial films with relatively small thickness (2.9 µm) show high quality, with the full-width at half-maximum values of GaN(11\\bar{2}0) along [1\\bar{1}00] direction and GaN(10\\bar{1}1) of 0.11 and 0.30°, and a root-mean-square surface roughness of 1.7 nm. This result is equivalent to the quality of the films grown by MOCVD with a thickness of 10 µm. This work provides a new and effective approach for achieving high-quality nonpolar a-plane GaN epitaxial films on r-plane sapphire substrates.

Fluence inhomogeneities due to a ripple filter induced Moiré effect.

PubMed

Ringbæk, Toke Printz; Brons, Stephan; Naumann, Jakob; Ackermann, Benjamin; Horn, Julian; Latzel, Harald; Scheloske, Stefan; Galonska, Michael; Bassler, Niels; Zink, Klemens; Weber, Uli

2015-02-07

At particle therapy facilities with pencil beam scanning, the implementation of a ripple filter (RiFi) broadens the Bragg peak, so fewer energy steps from the accelerator are required for a homogeneous dose coverage of the planning target volume (PTV). However, sharply focusing the scanned pencil beams at the RiFi plane by ion optical settings can lead to a Moiré effect, causing fluence inhomogeneities at the isocenter. This has been experimentally proven at the Heidelberg Ionenstrahl-Therapiezentrum (HIT), Universitätsklinikum Heidelberg, Germany. 150 MeV u(-1) carbon-12 ions are used for irradiation with a 3 mm thick RiFi. The beam is focused in front of and as close to the RiFi plane as possible. The pencil beam width is estimated to be 0.78 mm at a 93 mm distance from the RiFi. Radiographic films are used to obtain the fluence profile 30 mm in front of the isocenter, 930 mm from the RiFi. The Monte Carlo (MC) code SHIELD-HIT12A is used to determine the RiFi-induced inhomogeneities in the fluence distribution at the isocenter for a similar setup, pencil beam widths at the RiFi plane ranging from σχ(RiFi to 1.2 mm and for scanning step sizes ranging from 1.5 to 3.7 mm. The beam application and monitoring system (BAMS) used at HIT is modelled and simulated. When the width of the pencil beams at the RiFi plane is much smaller than the scanning step size, the resulting inhomogeneous fluence distribution at the RiFi plane interfers with the inhomogeneous RiFi mass distribution and fluence inhomogeneity can be observed at the isocenter as large as an 8% deviation from the mean fluence. The inverse of the fluence ripple period at the isocenter is found to be the difference between the inverse of the RiFi period and the inverse of the scanning step size. We have been able to use MC simulations to reproduce the spacing of the ripple stripes seen in films irradiated at HIT. Our findings clearly indicate that pencil beams sharply focused near the RiFi plane result in fluence inhomogeneity at the isocenter. In the normal clinical application, such a setting should generally be avoided.

Non-polar a-plane ZnO films grown on r-Al2O3 substrates using GaN buffer layers

NASA Astrophysics Data System (ADS)

Xu, C. X.; Chen, W.; Pan, X. H.; Chen, S. S.; Ye, Z. Z.; Huang, J. Y.

2016-09-01

In this work, GaN buffer layer has been used to grow non-polar a-plane ZnO films by laser-assisted and plasma-assisted molecular beam epitaxy. The thickness of GaN buffer layer ranges from ∼3 to 12 nm. The GaN buffer thickness effect on the properties of a-plane ZnO thin films is carefully investigated. The results show that the surface morphology, crystal quality and optical properties of a-plane ZnO films are strongly correlated with the thickness of GaN buffer layer. It was found that with 6 nm GaN buffer layer, a-plane ZnO films display the best crystal quality with X-ray diffraction rocking curve full-width at half-maximum of only 161 arcsec for the (101) reflection.

Anisotropic localized surface plasmon resonances in CuS nanoplates prepared by size-selective precipitation

NASA Astrophysics Data System (ADS)

Hamanaka, Yasushi; Yamada, Kaoru; Hirose, Tatsunori; Kuzuya, Toshihiro

2018-05-01

CuS nanoplates were synthesized by a colloidal method and separated into four fractions of nanoplates with different aspect ratios by a size-selective precipitation. In addition to a strong near infrared absorption band ascribed to the in-plane mode of the localized surface plasmon resonance (LSPR), we found a weak absorption band on the high frequency tail of the in-plane LSPR band. The frequency of the weak absorption band was almost constant and independent of the aspect ratio, while the in-plane LSPR band exhibited a strong aspect ratio dependence. These characteristics suggested that the weak absorption band is ascribed to the out-of-plane LSPR. Although the out-of-plane LSPR was expected to be difficult to observe for CuS nanoplates due to its low intensity and overlap with the strong in-plane resonance, we could successfully identify the out-of-plane mode by reducing the width of the size distribution and spectral broadening caused thereby.

Results of low speed wind tunnel tests on a .0405 scale model Rockwell Space Shuttle Orbiter tested both in free air and in the presence of a ground plane (OA16)

NASA Technical Reports Server (NTRS)

Mennell, R. C.; Cameron, B. W.

1974-01-01

Experimental aerodynamic investigations were conducted on a .0405 scale representation of the space shuttle orbiter in a 7.75 x 11 foot low speed wind tunnel during the time period March 21, to April 17, 1973. The primary test objectives were to investigate both the aerodynamic and propulsion effects of various air breathing engine systems in free air and in the presence of the ground. The free air portion of this test investigated the aerodynamic effects of engine nacelle number, nacelle grouping, and nacelle location. For this testing the model was sting mounted on a six component internal strain gage balance entering through the model base. The ground plane portion of the aerodynamic test investigated the same nacelle effects at ground plane locations of full scale W.P. = 239.9, 209.3, 158.9, 108.5, and 7.78 in. At the conclusion of the aerodynamic test period the propulsion effects of various nacelle locations and freestream orientations in the presence of the ground were investigated.

Tailoring of the partial magnonic gap in three-dimensional magnetoferritin-based magnonic crystals

NASA Astrophysics Data System (ADS)

Mamica, S.

2013-07-01

We investigate theoretically the use of magnetoferritin nanoparticles, self-assembled in the protein crystallization process, as the basis for the realization of 3D magnonic crystals in which the interparticle space is filled with a ferromagnetic material. Using the plane wave method we study the dependence of the width of the partial band gap and its central frequency on the total magnetic moment of the magnetoferritin core and the lattice constant of the magnetoferritin crystal. We show that by adjusting the combination of these two parameters the partial gap can be tailored in a wide frequency range and shifted to sub-terahertz frequencies. Moreover, the difference in the width of the partial gap for spin waves propagating in planes parallel and perpendicular to the external field allows for switching on and off the partial magnonic gap by changing the direction of the applied field.

Spectral Analysis of the Shuttle Glow. AIS Science Support

DTIC Science & Technology

1992-06-23

Prism (Total Internal Cylindrical Mirror Lens Reflection) Cylindrical Folding \\ Lens Plane Mirror -Cylindrical Slt Slit Mirror Fig. 7. Cron section...on Zerodur blanks, which width of the FOV to 0.14’ outward from the lens. have a coefficient of thermal expansion near zero. The width of the grating...oummambne toathe window of the iMag hunte~air. 3002. APPLIED OPTICS I VOL 3 .No, 16 / I June I02 68 Vacondry Minrror Prmr Mirror -luterence rlZters cm

The Shock and Vibration Digest. Volume 12, Number 8,

DTIC Science & Technology

1980-08-01

half tme coefficient of 0.315 in the above lamina. Sequential delamination began when a strip equation because two surfaces are formed). of width D in...a striker plate. Each specimen study of the two-dimensional ( plane -strain) response was subjected to two separate impact loadings: an of an elastic...laminated plate; they used a finite ele- in- plane impact and a so-called shear-bending impact. ment/normal mode technique. The physical behavior The

48 CFR 252.236-7005 - Airfield safety precautions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the maximum width of 16,000 feet at the end. (ii) The approach-departure clearance zone is the ground... ground area under the transitional surface. (It adjoins the primary surface, clear zone, and approach... while— (i) Operating all ground equipment (mobile or stationary); (ii) Placing all materials; and (iii...

Space Optical Communications Using Laser Beams

NASA Technical Reports Server (NTRS)

Goorjian, Peter M. (Inventor)

2017-01-01

A system for communicating between an object in space and a ground station, between objects in space, or between ground stations, includes a telecentric lens. Photodetectors positioned upon a focal plane of the telecentric lens detect an inbound light beam, received from a source, that has passed through the telecentric lens to the focal plane. Lasers positioned upon the focal plane transmit light beams from the focal plane through the telecentric lens to an area that includes the source of the inbound light beam. A processor detect signals from individual photodetectors corresponding to light detected, and selectively signals individual lasers that are close to those photodetectors, resulting in a returning beam that arrives close to the source, and which carries encoded data.

Photovoltaic module mounting clip with integral grounding

DOEpatents

Lenox, Carl J.

2008-10-14

An electrically conductive mounting/grounding clip, for use with a photovoltaic assembly of the type having an electrically conductive frame, comprises an electrically conductive body. The body has a central portion and first and second spaced-apart arms extending generally perpendicular to the central portion. Each arm has an outer portion with each outer portion having an outer end. At least one frame surface-disrupting element is at each outer end. The central portion defines a plane with the frame surface-disrupting elements pointing towards the plane. In some examples each arm extends from the central portion at an acute angle to the plane.

Cooling/grounding mount for hybrid circuits

NASA Technical Reports Server (NTRS)

Bagstad, B.; Estrada, R.; Mandel, H.

1981-01-01

Extremely short input and output connections, adequate grounding, and efficient heat removal for hybrid integrated circuits are possible with mounting. Rectangular clamp holds hybrid on printed-circuit board, in contact with heat-conductive ground plate. Clamp is attached to ground plane by bolts.

Central tracker for BM@N experiment based on double side Si-microstrip detectors

NASA Astrophysics Data System (ADS)

Kovalev, Yu.; Kapishin, M.; Khabarov, S.; Shafronovskaia, A.; Tarasov, O.; Makankin, A.; Zamiatin, N.; Zubarev, E.

2017-07-01

Design of central tracker system based on Double-Sided Silicon Detectors (DSSD) for BM@N experiment is described. A coordinate plane with 10240 measuring channels, pitch adapter, reading electronics was developed. Each element was tested and assembled into a coordinate plane. The first tests of the plane with 106Ru source were carried out before installation for the BM@N experiment. The results of the study indicate that noisy channels and inefficient channels are less than 3%. In general, single clusters 87% (one group per module of consecutive strips) and 75% of clusters with a width equal to one strip.

Remarkably enhanced current-driven 360° domain wall motion in nanostripe by tuning in-plane biaxial anisotropy.

PubMed

Su, Yuanchang; Weng, Lianghao; Dong, Wenjun; Xi, Bin; Xiong, Rui; Hu, Jingguo

2017-10-17

By micromagnetic simulations, we study the current-driven 360° domain wall (360DW) motion in ferromagnetic nanostripe with an in-plane biaxial anisotropy. We observe the critical annihilation current of 360° domain wall can be enhanced through such a type of anisotropy, the reason of which is the suppression of out-of-plane magnetic moments generated simultaneously with domain-wall motion. In details, We have found that the domain-wall width is only related to K y  - K x , with K x(y) the anisotropy constant in x(y) direction. Taking domain-wall width into consideration, a prior choice is to keep K y  ≈ K x with large enough K. The mode of domain-wall motion has been investigated as well. The traveling-wave-motion region increases with K, while the average DW velocity is almost unchanged. Another noteworthy feature is that a Walker-breakdown-like motion exists before annihilation. In this region, though domain wall moves with an oscillating behavior, the average velocity does not reduce dramatically, but even rise again for a large K.

An inverse inviscid method for the design of quasi-three dimensional rotating turbomachinery cascades

NASA Technical Reports Server (NTRS)

Bonataki, E.; Chaviaropoulos, P.; Papailiou, K. D.

1991-01-01

A new inverse inviscid method suitable for the design of rotating blade sections lying on an arbitrary axisymmetric stream-surface with varying streamtube width is presented. The geometry of the axisymmetric stream-surface and the streamtube width variation with meridional distance, the number of blades, the inlet flow conditions, the rotational speed and the suction and pressure side velocity distributions as functions of the normalized arc-length are given. The flow is considered irrotational in the absolute frame of reference and compressible. The output of the computation is the blade section that satisfies the above data. The method solves the flow equations on a (phi 1, psi) potential function-streamfunction plane for the velocity modulus, W and the flow angle beta; the blade section shape can then be obtained as part of the physical plane geometry by integrating the flow angle distribution along streamlines. The (phi 1, psi) plane is defined so that the monotonic behavior of the potential function is guaranteed, even in cases with high peripheral velocities. The method is validated on a rotating turbine case and used to design new blades. To obtain a closed blade, a set of closure conditions were developed and referred.

Calculated SAR distributions in a human voxel phantom due to the reflection of electromagnetic fields from a ground plane between 65 MHz and 2 GHz

NASA Astrophysics Data System (ADS)

Findlay, R. P.; Dimbylow, P. J.

2008-05-01

If an electromagnetic field is incident normally onto a perfectly conducting ground plane, the field is reflected back into the domain. This produces a standing wave above the ground plane. If a person is present within the domain, absorption of the field in the body may cause problems regarding compliance with electromagnetic guidelines. To investigate this, the whole-body averaged specific energy absorption rate (SAR), localised SAR and ankle currents in the voxel model NORMAN have been calculated for a variety of these exposures under grounded conditions. The results were normalised to the spatially averaged field, a technique used to determine a mean value for comparison with guidelines when the field varies along the height of the body. Additionally, the external field values required to produce basic restrictions for whole-body averaged SAR have been calculated. It was found that in all configurations studied, the ICNIRP reference levels and IEEE MPEs provided a conservative estimate of these restrictions.

High Latitude Polygons

NASA Technical Reports Server (NTRS)

2005-01-01

26 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygonal patterned ground on a south high-latitude plain. The outlines of the polygons, like the craters and hills in this region, are somewhat enhanced by the presence of bright frost left over from the previous winter. On Earth, polygons at high latitudes would usually be attributed to the seasonal freezing and thawing cycles of ground ice. The origin of similar polygons on Mars is less certain, but might also be an indicator of ground ice.

Location near: 75.3oS, 113.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

SYSTEM FOR AND METHOD OF DETERMINING RANGE

DOEpatents

Horrell, M.W.; Sanders, E.R.

1963-11-01

A system and method for indicating a predetermined altitude of an object or aircraft is described. The device utilizes a pulse transmit-receive system wherein pulses of predetermined width are transmitted towards the ground and the reflected pulses received gating only pulses having a predetermined width. (AEC)

Three-dimensional broadband ground-plane cloak made of metamaterials

PubMed Central

Ma, Hui Feng; Cui, Tie Jun

2010-01-01

Since invisibility cloaks were first suggested by transformation optics theory, there has been much work on the theoretical analysis and design of various types and a few experimental verifications at microwave and optical frequencies within two-dimensional limits. Here, we realize the first practical implementation of a fully 3D broadband and low-loss ground-plane cloak at microwave frequencies. The cloak, realized by drilling inhomogeneous holes in multi-layered dielectric plates, can conceal a 3D object located under a curved conducting plane from all viewing angles by imitating the reflection of a flat conducting plane. We also designed and realized, using non-resonant metamaterials, a high-gain lens antenna that can produce narrow-beam plane waves in the near-field region in a broad frequency band. The antenna constitutes the transmitter of the measurement system and is essential for the measurement of cloaking behaviour. PMID:20975696

Ground-plane influences on size estimation in early visual processing.

PubMed

Champion, Rebecca A; Warren, Paul A

2010-07-21

Ground-planes have an important influence on the perception of 3D space (Gibson, 1950) and it has been shown that the assumption that a ground-plane is present in the scene plays a role in the perception of object distance (Bruno & Cutting, 1988). Here, we investigate whether this influence is exerted at an early stage of processing, to affect the rapid estimation of 3D size. Participants performed a visual search task in which they searched for a target object that was larger or smaller than distracter objects. Objects were presented against a background that contained either a frontoparallel or slanted 3D surface, defined by texture gradient cues. We measured the effect on search performance of target location within the scene (near vs. far) and how this was influenced by scene orientation (which, e.g., might be consistent with a ground or ceiling plane, etc.). In addition, we investigated how scene orientation interacted with texture gradient information (indicating surface slant), to determine how these separate cues to scene layout were combined. We found that the difference in target detection performance between targets at the front and rear of the simulated scene was maximal when the scene was consistent with a ground-plane - consistent with the use of an elevation cue to object distance. In addition, we found a significant increase in the size of this effect when texture gradient information (indicating surface slant) was present, but no interaction between texture gradient and scene orientation information. We conclude that scene orientation plays an important role in the estimation of 3D size at an early stage of processing, and suggest that elevation information is linearly combined with texture gradient information for the rapid estimation of 3D size. Copyright 2010 Elsevier Ltd. All rights reserved.

The effects of eccentricities on the fracture of off-axis fiber composites. [carbon fiber reinforced plastics

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Sinclair, J. H.

1978-01-01

Finite element analyses were performed to investigate theoretically the effects of in-plane and out-of-plane eccentricities, bending or twisting, and thickness nonuniformity on the axial stress and strain variations across the width of off-axis specimens. The results are compared with measured data and are also used to assess the effects of these eccentricities on the fracture stress of off-axis fiber composites. Guidelines for detecting and minimizing the presence of eccentricities are described.

The effects of eccentricities on the fracture of off-axis fiber composites

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Sinclair, J. H.

1978-01-01

Finite element analyses were performed to investigate theoretically the effects of in-plane and out-of plane eccentricities, bending or twisting, and thickness nonuniformity on the axial stress and strain variations across the width of off-axis specimens. The results are compared with measured data and are also used to access the effects of these eccentricities on the fracture stress of off-axis fiber composites. Guidelines for detecting and minimizing the presence of eccentricities are described.

Scratching experiments on quartz crystals: Orientation effects in chipping

NASA Astrophysics Data System (ADS)

Tellier, C. R.; Benmessaouda, D.

1994-06-01

The deformation and microfracture properties of quartz crystals were studied by scratching experiments. The critical load at which microfractures are initiated was found to be orientation dependent, whereas the average width of ductile grooves and chips remained relatively insensitive to crystal orientation. In contrast, a marked anisotropy in the shape of chips was observed. This anisotropy has been interpreted in terms of microfractures propagating preferentially along slip planes. Simple geometrical conditions for the SEM (scanning electron microscopy) observation of active slip planes are proposed.

Characterizing the structural maturity of fault zones using high-resolution earthquake locations.

NASA Astrophysics Data System (ADS)

Perrin, C.; Waldhauser, F.; Scholz, C. H.

2017-12-01

We use high-resolution earthquake locations to characterize the three-dimensional structure of active faults in California and how it evolves with fault structural maturity. We investigate the distribution of aftershocks of several recent large earthquakes that occurred on immature faults (i.e., slow moving and small cumulative displacement), such as the 1992 (Mw7.3) Landers and 1999 (Mw7.1) Hector Mine events, and earthquakes that occurred on mature faults, such as the 1984 (Mw6.2) Morgan Hill and 2004 (Mw6.0) Parkfield events. Unlike previous studies which typically estimated the width of fault zones from the distribution of earthquakes perpendicular to the surface fault trace, we resolve fault zone widths with respect to the 3D fault surface estimated from principal component analysis of local seismicity. We find that the zone of brittle deformation around the fault core is narrower along mature faults compared to immature faults. We observe a rapid fall off of the number of events at a distance range of 70 - 100 m from the main fault surface of mature faults (140-200 m fault zone width), and 200-300 m from the fault surface of immature faults (400-600 m fault zone width). These observations are in good agreement with fault zone widths estimated from guided waves trapped in low velocity damage zones. The total width of the active zone of deformation surrounding the main fault plane reach 1.2 km and 2-4 km for mature and immature faults, respectively. The wider zone of deformation presumably reflects the increased heterogeneity in the stress field along complex and discontinuous faults strands that make up immature faults. In contrast, narrower deformation zones tend to align with well-defined fault planes of mature faults where most of the deformation is concentrated. Our results are in line with previous studies suggesting that surface fault traces become smoother, and thus fault zones simpler, as cumulative fault slip increases.

USAF Radiofrequency Radiation Bioeffects Research Program - A Review

DTIC Science & Technology

1981-12-01

Experimental Methods--SARa have been measured in scaled saline spheroidal phantoms irradiated by the near fields of short electric monopoles above ground planes...aperture analysis might be the case where some industrial machines have an equivalent electric dipole parallel to the operator, which causes maximum...short electric monopoles on a ground plane simulating electric dipoles. Some results of these measurements are shown in Fig. 16, with the measured

High voltage variable diameter insulator

DOEpatents

Vanecek, David L.; Pike, Chester D.

1984-01-01

A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

Test Of A Microwave Amplifier With Superconductive Filter

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Toncich, S. S.; Chorey, C. M.; Bonetti, R. R.; Williams, A. E.

1995-01-01

Report describes design and low-temperature tests of low-noise GaAs microwave amplifier combined with microstrip band-pass filter. Two versions of microstrip filter used in alternate tests; in one version, microstrips formed as films of high-transition-temperature superconductor Y/Ba/Cu/O on lanthanum aluminate substrate with gold film as ground plane. Other version identical except microstrips as well as ground plane made of gold, normally conductive.

Computer Program for Thin Wire Antenna over a Perfectly Conducting Ground Plane. [using Galerkins method and sinusoidal bases

NASA Technical Reports Server (NTRS)

Richmond, J. H.

1974-01-01

A computer program is presented for a thin-wire antenna over a perfect ground plane. The analysis is performed in the frequency domain, and the exterior medium is free space. The antenna may have finite conductivity and lumped loads. The output data includes the current distribution, impedance, radiation efficiency, and gain. The program uses sinusoidal bases and Galerkin's method.

Sweep Width Estimation for Ground Search and Rescue

DTIC Science & Technology

2004-12-30

Develop data compatible with search planning and POD estimation methods that are de- signed to use sweep width data. An experimental...important for Park Rangers and man- trackers . Search experience was expected to be a significant correction factor. However, the re- sults indicate...41 4.1.1 Signing In

Bias of cylinder diameter estimation from ground-based laser scanners with different beam widths: A simulation study

NASA Astrophysics Data System (ADS)

Forsman, Mona; Börlin, Niclas; Olofsson, Kenneth; Reese, Heather; Holmgren, Johan

2018-01-01

In this study we have investigated why diameters of tree stems, which are approximately cylindrical, are often overestimated by mobile laser scanning. This paper analyzes the physical processes when using ground-based laser scanning that may contribute to a bias when estimating cylinder diameters using circle-fit methods. A laser scanner simulator was implemented and used to evaluate various properties, such as distance, cylinder diameter, and beam width of a laser scanner-cylinder system to find critical conditions. The simulation results suggest that a positive bias of the diameter estimation is expected. Furthermore, the bias follows a quadratic function of one parameter - the relative footprint, i.e., the fraction of the cylinder width illuminated by the laser beam. The quadratic signature opens up a possibility to construct a compensation model for the bias.

A Dual Mode BPF with Improved Spurious Response Using DGS Cells Embedded on the Ground Plane of CPW

NASA Astrophysics Data System (ADS)

Weng, Min-Hang; Ye, Chang-Sin; Hung, Cheng-Yuan; Huang, Chun-Yueh

A novel dual mode bandpass filter (BPF) with improved spurious response is presented in this letter. To obtain low insertion loss, the coupling structure using the dual mode resonator and the feeding scheme using coplanar-waveguide (CPW) are constructed on the two sides of a dielectric substrate. A defected ground structure (DGS) is designed on the ground plane of the CPW to achieve the goal of spurious suppression of the filter. The filter has been investigated numerically and experimentally. Measured results show a good agreement with the simulated analysis.

Grizzly bear (Ursus arctos horribilis) locomotion: forelimb joint mechanics across speed in the sagittal and frontal planes.

PubMed

Shine, Catherine L; Robbins, Charles T; Nelson, O Lynne; McGowan, Craig P

2017-04-01

The majority of terrestrial locomotion studies have focused on parasagittal motion and paid less attention to forces or movement in the frontal plane. Our previous research has shown that grizzly bears produce higher medial ground reaction forces (lateral pushing from the animal) than would be expected for an upright mammal, suggesting frontal plane movement may be an important aspect of their locomotion. To examine this, we conducted an inverse dynamics analysis in the sagittal and frontal planes, using ground reaction forces and position data from three high-speed cameras of four adult female grizzly bears. Over the speed range collected, the bears used walks, running walks and canters. The scapulohumeral joint, wrist and the limb overall absorb energy (average total net work of the forelimb joints, -0.97 W kg -1 ). The scapulohumeral joint, elbow and total net work of the forelimb joints have negative relationships with speed, resulting in more energy absorbed by the forelimb at higher speeds (running walks and canters). The net joint moment and power curves maintain similar patterns across speed as in previously studied species, suggesting grizzly bears maintain similar joint dynamics to other mammalian quadrupeds. There is no significant relationship with net work and speed at any joint in the frontal plane. The total net work of the forelimb joints in the frontal plane was not significantly different from zero, suggesting that, despite the high medial ground reaction forces, the forelimb acts as a strut in that plane. © 2017. Published by The Company of Biologists Ltd.

LEO-ground scintillation measurements with the optical ground station Oberpfaffenhofen and SOTA/OPALS space terminals

NASA Astrophysics Data System (ADS)

Moll, Florian; Kolev, Dimitar; Abrahamson, Matthew; Schmidt, Christopher; Mata Calvo, Ramon; Fuchs, Christian

2016-10-01

The optical satellite-ground channel is turbulent and causes scintillation of the power received by a ground based telescope. Measurements are important to quantify the effect and evaluate common theory. A telescope with 40 cm primary mirror is used to measure the signals from the OPALS terminal on the International Space Station and the SOTA terminal on the SOCRATES satellite. The measurement instrument is a pupil camera from which images are recorded and intensity scintillation index, power scintillation index, probability density function of intensity and intensity correlation width are derived. A preliminary analysis of measurements from three satellite passed is performed, presented and discussed. The intensity scintillation index ranges from 0.25 to 0.03 within elevations of 26 to 66 deg. Power scintillation index varies from 0.08 to 0.006 and correlation width of intensity between 11 and 3 cm. The measurements can be used to estimate the fluctuation dynamics to be expected for a future operational ground receiver. The measurements are compared to model calculations based on the HV5/7-profile. Good agreement is observed to some part in the intensity scintillation index. Agreement is less for the power scintillation index and intensity correlation width. The reason seems to be a reduction of aperture averaging in some sections of the measurements due to increased speckle size. Finally, topics for future work are identified to improve the measurement analysis and deeper investigate the origin of the observed behavior.

Spectral Analysis of the Shuttle Glow. SPAS II/IBSS Mission - AIS hardware

DTIC Science & Technology

1992-04-23

Mirror Lens C Reflection) CiraCylindrical/-Lens • Plane Mirror j _Slit Slit Mro Fig. 7. Cross section through the reflective foreoptics of the UV Fig. 6...selection. The gratings in the The slit width of 0.045 mm restricted the angular spectrograph are deposited on Zerodur blanks, which width of the FOV...of th*i short fee-1 hlaa, t do, lmw b*WdW 3Wa APO=E OPTIC I VOL 31, ft. 16 1 1~ toes I 48 Secondary Mlirror Primary Mirror - lntaeranas Ptten Image

Silicon base plate with low parasitic electrical interference for sensors

NASA Technical Reports Server (NTRS)

Tang, Tony K. (Inventor); Gutierrez, Roman C. (Inventor)

2002-01-01

A microgyroscope has a baseplate made of the same material as the rest of the microgyroscope. The baseplate is a silicon baseplate having a heavily p-doped epilayer covered by a thick dielectric film and metal electrodes. The metal electrodes are isolated from the ground plane by the dielectric. This provides very low parasitic capacitive coupling between the electrodes. The thick dielectric reduces the capacitance between the electrodes and the ground plane.

Antenna with Dielectric Having Geometric Patterns

NASA Technical Reports Server (NTRS)

Dudley, Kenneth L. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor); Elliott, Holly A. (Inventor)

2013-01-01

An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.

Properties of cutoff corrugated surfaces for corrugated horn design. [corrugation shape and density effects on scattering

NASA Technical Reports Server (NTRS)

Mentzer, C. A.; Peters, L., Jr.

1974-01-01

Corrugated horns involve a junction between the corrugated surface and a conducting ground plane. Proper horn design requires an understanding of the electromagnetic properties of the corrugated surface and this junction. An integral equation solution has been used to study the influence of corrugation density and tooth thickness on the power loss, surface current, and the scattering from a ground plane/corrugated surface junction.

Printed circuit board impedance matching step for microwave (millimeter wave) devices

DOEpatents

Pao, Hsueh-Yuan; Aguirre, Jerardo; Sargis, Paul

2013-10-01

An impedance matching ground plane step, in conjunction with a quarter wave transformer section, in a printed circuit board provides a broadband microwave matching transition from board connectors or other elements that require thin substrates to thick substrate (>quarter wavelength) broadband microwave (millimeter wave) devices. A method of constructing microwave and other high frequency electrical circuits on a substrate of uniform thickness, where the circuit is formed of a plurality of interconnected elements of different impedances that individually require substrates of different thicknesses, by providing a substrate of uniform thickness that is a composite or multilayered substrate; and forming a pattern of intermediate ground planes or impedance matching steps interconnected by vias located under various parts of the circuit where components of different impedances are located so that each part of the circuit has a ground plane substrate thickness that is optimum while the entire circuit is formed on a substrate of uniform thickness.

Novel Micro Strip-to-Waveguide Feed Employing a Double-Y Junction

NASA Technical Reports Server (NTRS)

Venkatesan, Jaikrishina

2010-01-01

Previous micro strip -to -waveguide transitions either required a hermetically sealed waveguide configuration, or a balun that needed to be tuned according to the frequency band of interest. In this design, the balun is realized using a double -Y junction to transition from microstrip to coplanar strip feeding a quasi-Yagi dipole array (see figure). The length of the feed (Lf) extending into the waveguide is 15.54 mm. The length of the ground plane below the ULTRALAM substrate is 7.75 mm. The lengths L1 , L2, and L3 are 8.50 mm, 4.38 mm, and 2.14 mm, respectively. These lengths were computed via a preliminary optimization aimed at improving the return loss at the band edges. The waveguide feed was designed to excite the TE10 mode in a WR-90 waveguide, and to operate over the recommended frequencies of 8.2 to 12.4 GHz. The feed employs a Rogers 6010 substrate (dielectric constant Er approx. equals 10.2) bonded with a Rogers ULTRALAM substrate (Er approx. equals 2.5). The ULTRALAM substrate serves to provide mechanical strength for 6010 substrate, and to mitigate loses due to parasitic modes (the ground plane is etched on the bottom of this layer due to the topology of the double -Y balun). The double-Y balun transitioning from an unbalanced microstrip line to a balanced coplanar strip (CPS) line does not provide inherent impedance transformation; hence, Klopfenstein impedance tapers were synthesized to transition from 50 to 77 Ohms in the microstrip section and from 77 to 110 Ohms in the CPS section. At the balun junction, the CPS stub lengths were chosen such that the X/ 8 resonance is pushed outside the bandwidth of operation. Also, the smallest allowable conductor width and gap spacing were chosen to meet acceptable manufacturing tolerances.

Strength of Rectangular Flat Plates Under Edge Compression

NASA Technical Reports Server (NTRS)

Schuman, Louis; Back, Goldie

1931-01-01

Flat rectangular plates of duralumin, stainless iron, monel metal, and nickel were tested under loads applied at two opposite edges and acting in the plane of the plate. The edges parallel to the direction of loading were supported in V grooves. The plates were all 24 inches long and varied in width from 4 to 24 inches by steps of 4 inches, and in thickness from 0.015 to 0.095 inch by steps of approximately 0.015 inch. There were also a few 1, 2, 3, and 6 inch wide specimens. The loads were applied in the testing machine at the center of a bar which rested along the top of the plate. Load was applied until the plate failed to take any more load. The tests show that the loads carried by the plates generally reached a maximum for the 8 or 12 inch width and that there was relatively small drop in load for the greater widths. Deflection and set measurement perpendicular to the plane of the plate were taken and the form of the buckle determined. The number of buckles were found to correspond in general to that predicted by the theory of buckling of a plate uniformly loaded at two opposite edges and simply supported at the edges.

Enhancement of low power CO2 laser cutting process for injection molded polycarbonate

NASA Astrophysics Data System (ADS)

Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.

2017-11-01

Laser cutting technology is a non-contact process that typically is used for industrial manufacturing applications. Laser cut quality is strongly influenced by the cutting processing parameters. In this research, CO2 laser cutting specifications have been investigated by using design of experiments (DOE) with considering laser cutting speed, laser power and focal plane position as process input parameters and kerf geometry dimensions (i.e. top and bottom kerf width, ratio of the upper kerf to lower kerf, upper heat affected zone (HAZ)) and surface roughness of the kerf wall as process output responses. A 60 Watts CO2 laser cutting machine is used for cutting the injection molded samples of polycarbonate sheet with the thickness of 3.2 mm. Results reveal that by decreasing the laser focal plane position and laser power, the bottom kerf width will be decreased. Also the bottom kerf width decreases by increasing the cutting speed. As a general result, locating the laser spot point in the depth of the workpiece the laser cutting quality increases. Minimum value of the responses (top kerf, heat affected zone, ratio of the upper kerf to lower kerf, and surface roughness) are considered as optimization criteria. Validating the theoretical results using the experimental tests is carried out in order to analyze the results obtained via software.

Measurement and dynamics of the spatial distribution of an electron localized at a metal-dielectric interface

NASA Astrophysics Data System (ADS)

Bezel, Ilya; Gaffney, Kelly J.; Garrett-Roe, Sean; Liu, Simon H.; Miller, André D.; Szymanski, Paul; Harris, Charles B.

2004-01-01

The ability of time- and angle-resolved two-photon photoemission to estimate the size distribution of electron localization in the plane of a metal-adsorbate interface is discussed. It is shown that the width of angular distribution of the photoelectric current is inversely proportional to the electron localization size within the most common approximations in the description of image potential states. The localization of the n=1 image potential state for two monolayers of butyronitrile on Ag(111) is used as an example. For the delocalized n=1 state, the shape of the signal amplitude as a function of momentum parallel to the surface changes rapidly with time, indicating efficient intraband relaxation on a 100 fs time scale. For the localized state, little change was observed. The latter is related to the constant size distribution of electron localization, which is estimated to be a Gaussian with a 15±4 Å full width at half maximum in the plane of the interface. A simple model was used to study the effect of a weak localization potential on the overall width of the angular distribution of the photoemitted electrons, which exhibited little sensitivity to the details of the potential. This substantiates the validity of the localization size estimate.

Investigation of impingement region and wall jets formed by the interaction of high aspect ratio lift jets and a ground plane

NASA Technical Reports Server (NTRS)

Kotansky, D. R.; Glaze, L. W.

1978-01-01

Flow characteristics of impinging jets emanating from rectangular exit area converging nozzles of exit area aspect ratio four, six, and eight were investigated. Azimuthal distributions of wall jet radial momentum flux in the ground plane were strongly directional and sensitive to rectangular nozzle exit area aspect ratio, jet impingement angle, and height above ground, H/D. Effects of jet exit velocity profile nonuniformities were also investigated. Data from the single nozzle rectangular jet impringement investigations were incorporated into an existing VTOL aircraft ground flow field computer program. It is suggested that this program together with the Douglas Neumann program modified for V/STOL applications may be used for the analysis and prediction of flow fields and resulting forces and moments on multijet V/STOL aircraft hovering in ground effect.

Printed wide-slot antenna design with bandwidth and gain enhancement on low-cost substrate.

PubMed

Samsuzzaman, M; Islam, M T; Mandeep, J S; Misran, N

2014-01-01

This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS.

Printed Wide-Slot Antenna Design with Bandwidth and Gain Enhancement on Low-Cost Substrate

PubMed Central

Samsuzzaman, M.; Islam, M. T.; Mandeep, J. S.; Misran, N.

2014-01-01

This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS. PMID:24696661

A Simplified Guidance for Target Missiles Used in Ballistic Missile Defence Evaluation

NASA Astrophysics Data System (ADS)

Prabhakar, N.; Kumar, I. D.; Tata, S. K.; Vaithiyanathan, V.

2013-01-01

A simplified guidance scheme for the target missiles used in Ballistic Missile Defence is presented in this paper. The proposed method has two major components, a Ground Guidance Computation (GGC) and an In-Flight Guidance Computation. The GGC which runs on the ground uses a missile model to generate attitude history in pitch plane and computes launch azimuth of the missile to compensate for the effect of earth rotation. The vehicle follows the pre launch computed attitude (theta) history in pitch plane and also applies the course correction in azimuth plane based on its deviation from the pre launch computed azimuth plane. This scheme requires less computations and counters In-flight disturbances such as wind, gust etc. quite efficiently. The simulation results show that the proposed method provides the satisfactory performance and robustness.

Designing broad phononic band gaps for in-plane modes

NASA Astrophysics Data System (ADS)

Li, Yang Fan; Meng, Fei; Li, Shuo; Jia, Baohua; Zhou, Shiwei; Huang, Xiaodong

2018-03-01

Phononic crystals are known as artificial materials that can manipulate the propagation of elastic waves, and one essential feature of phononic crystals is the existence of forbidden frequency range of traveling waves called band gaps. In this paper, we have proposed an easy way to design phononic crystals with large in-plane band gaps. We demonstrated that the gap between two arbitrarily appointed bands of in-plane mode can be formed by employing a certain number of solid or hollow circular rods embedded in a matrix material. Topology optimization has been applied to find the best material distributions within the primitive unit cell with maximal band gap width. Our results reveal that the centroids of optimized rods coincide with the point positions generated by Lloyd's algorithm, which deepens our understandings on the formation mechanism of phononic in-plane band gaps.

Using step width to compare locomotor biomechanics between extinct, non-avian theropod dinosaurs and modern obligate bipeds.

PubMed

Bishop, P J; Clemente, C J; Weems, R E; Graham, D F; Lamas, L P; Hutchinson, J R; Rubenson, J; Wilson, R S; Hocknull, S A; Barrett, R S; Lloyd, D G

2017-07-01

How extinct, non-avian theropod dinosaurs locomoted is a subject of considerable interest, as is the manner in which it evolved on the line leading to birds. Fossil footprints provide the most direct evidence for answering these questions. In this study, step width-the mediolateral (transverse) distance between successive footfalls-was investigated with respect to speed (stride length) in non-avian theropod trackways of Late Triassic age. Comparable kinematic data were also collected for humans and 11 species of ground-dwelling birds. Permutation tests of the slope on a plot of step width against stride length showed that step width decreased continuously with increasing speed in the extinct theropods ( p < 0.001), as well as the five tallest bird species studied ( p < 0.01). Humans, by contrast, showed an abrupt decrease in step width at the walk-run transition. In the modern bipeds, these patterns reflect the use of either a discontinuous locomotor repertoire, characterized by distinct gaits (humans), or a continuous locomotor repertoire, where walking smoothly transitions into running (birds). The non-avian theropods are consequently inferred to have had a continuous locomotor repertoire, possibly including grounded running. Thus, features that characterize avian terrestrial locomotion had begun to evolve early in theropod history. © 2017 The Author(s).

FERMI BUBBLES AND BUBBLE-LIKE EMISSION FROM THE GALACTIC PLANE

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Boer, Wim; Weber, Markus, E-mail: wim.de.boer@kit.edu, E-mail: markus.weber2@kit.edu

2014-10-10

The diffuse gamma-ray sky revealed ''bubbles'' of emission above and below the Galactic plane, symmetric around the center of the Milky Way, with a height of 10 kpc in both directions. At present, there is no convincing explanation for the origin. To understand the role of the Galactic center, one has to study the bubble spectrum inside the disk, a region that has been excluded from previous analyses because of the large foreground. From a novel template fit, which allows a simultaneous determination of the signal and foreground in any direction, we find that bubble-like emission is not only found inmore » the halo, but in the Galactic plane as well, with a width in latitude coinciding with the molecular clouds. The longitude distribution has a width corresponding to the Galactic bar with an additional contribution from the Scutum-Centaurus arm. The energy spectrum of the bubbles coincides with the predicted contribution from CRs trapped in sources (SCRs). Also, the energetics fits well. Hence, we conclude that the bubble-like emission has a hadronic origin that arises from SCRs, and the bubbles in the halo arise from hadronic interactions in advected gas. Evidence for advection is provided by the ROSAT X-rays of hot gas in the bubble region.« less

Electrophoresis in ice surface grooves for probing protein affinity to a specific plane of ice crystal.

PubMed

Inagawa, Arinori; Okada, Yusuke; Okada, Tetsuo

2018-06-01

Channel-like grooves are formed on the surface of frozen aqueous sucrose. They are filled with a freeze concentrated solution (FCS) and act as an efficient size-tunable separation field for micro and nanoparticles. The width of the channel can be easily varied by changing the temperature. Because the channel width decreases with decreasing temperature, particles become immobilized due to physical interference from the ice wall when the temperature reaches a threshold point specific to the particle size. Surface modification of particles can add a factor of chemical interaction between the particles and ice walls. In this study, anti-freeze proteins (AFPs) are anchored on 1µm-polystyrene (PS) particles, and their behavior in the surface grooves on the ice is studied. The threshold temperature is an effective criterion for evaluating chemical interactions between particles and ice walls. The AFP binding on 1µm PS particles lowers the threshold temperature by 2.5°C, indicating interactions between AFPs on the PS particles and the ice wall. Because the AFPs studied here show selectivity towards the prism plane, it is critical that the prism plane of the ice crystal is in contact with the FCS in the surface grooves. Copyright © 2017 Elsevier B.V. All rights reserved.

Size effect on cold-welding of gold nanowires investigated using molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Wu, Cheng-Da; Fang, Te-Hua; Wu, Chung-Chin

2016-03-01

The size effect on the cold-welding mechanism and mechanical properties of Au nanowires (NWs) in head-to-head contact are studied using molecular dynamics simulations based on the second-moment approximation of the many-body tight-binding potential. The results are discussed in terms of atomic trajectories, slip vectors, stress, radial distribution function, and weld strength ratio. Simulation results show that during the cold-welding process, a few disordered atoms/defects in the jointing area rearrange themselves and transform into a face-centered cubic crystalline structure. With an increase in contact between the two NWs, dislocations gradually form on the (111) slip plane and then on a twin plane, leading to an increase in the lateral deformation of 4-nm-wide NWs. The effect of structural instability increases with decreasing NW width, making the alignment of the two NWs more difficult. The elongation ability of the welded NWs increases with increasing NW width. Smaller NWs have better weld strength.

Flow Resistivity Instrument

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J. (Inventor)

1983-01-01

A method and apparatus for making in-situ measurements of flow resistivity on the Earth's ground surface is summarized. The novel feature of the invention is two concentric cylinders, inserted into the ground surface with a measured pressure applied to the surface inside the inner cylinder. The outer cylinder vents a plane beneath the surface to the atmosphere through an air space. The flow to the inner cylinder is measured thereby indicating the flow from the surface to the plane beneath the surface.

Note on use of slope diffraction coefficients for aperture antennas on finite ground planes

NASA Technical Reports Server (NTRS)

Cockrell, C. R.; Beck, F. B.

1995-01-01

The use of slope diffraction coefficients along with regular diffraction coefficients for calculating the radiation patterns of aperture antennas in a finite ground plane is investigated. Explicit expressions for regular diffraction coefficients and slope diffraction coefficients are presented. The expressions for the incident magnetic field in terms of the magnetic current in the aperture are given. The slope of the incident magnetic field is calculated and closed form expressions are presented.

Mixed configuration ground state in iron(II) phthalocyanine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernández-Rodríguez, Javier; Toby, Brian; van Veenendaal, Michel

2015-06-01

We calculate the angular dependence of the x-ray linear and circular dichroism at the L2,3 edges of α-Fe(II) Phthalocyanine (FePc) thin films using a ligand-field model with full configuration interaction. We find the best agreement with the experimental spectra for a mixed ground state of 3E (a2 e3b1 ) and 3B (a1 e4b1 ) g 1g g 2g 2g 1g g 2g with the two configurations coupled by the spin-orbit interaction. The 3Eg(b) and 3B2g states have easy-axis and easy-plane anisotropies, respectively. Our model accounts for an easy-plane magnetic anisotropy and the measured magnitudes of the in-plane orbital and spinmore » moments. The proximity in energy of the two configurations allows a switching of the magnetic anisotropy from easy plane to easy axis with a small change in the crystal field, as recently observed for FePc adsorbed on an oxidized Cu surface. We also discuss the possibility of a quintet ground state (5A1g is 250 meV above the ground state) with planar anisotropy by manipulation of the Fe-C bond length by depositing the complex on a substrate that is subjected to a mechanical strain.« less

The EarthCARE multi spectral imager thermal infrared optical unit

NASA Astrophysics Data System (ADS)

Chang, M. P. J. L.; Woods, D.; Baister, Guy; Lobb, Dan; Wood, Trevor

2017-11-01

The EarthCARE satellite mission objective is the observation of clouds and aerosols from low Earth orbit. The key spatial context providing instrument within the payload suite of 4 instruments is the Multi-Spectral Imager (MSI), previously described in [1]. The MSI is intended to provide information on the horizontal variability of the atmospheric conditions and to identify e.g. cloud type, textures, and temperature. It will form Earth images at 500m ground sample distance (GSD) over a swath width of 150km; it will image Earth in 7 spectral bands: one visible, one near-IR, two short-wave IR and three thermal IR. The instrument will be comprised of two key parts: • a visible-NIR-SWIR (VNS) optical unit radiometrically calibrated using a sun illuminated quasivolume diffuser and shutter system • a thermal IR (TIR) optical unit radiometrically calibrated using cold space and an internal black-body. This paper, being the first of a sequence of two, will provide an overview of the MSI and enter into more detail the critical performance parameters and detailed design the MSI TIR optical design. The TIR concept is to provide pushbroom imaging of its 3 bands through spectral separation from a common aperture. The result is an efficient, well controlled optical design without the need for multiple focal plane arrays. The designed focal plane houses an area array detector and will meet a challenging set of requirements, including radiometric resolution, accuracy, distortion and MTF.

Stratification of a two-phase monodisperse system in a plane laminar flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fedoseev, V. B., E-mail: vbfedoseev@yandex.ru

2016-05-15

A thermodynamic approach is used to describe the distribution of particles of a disperse phase in a plane laminar flow. The effect of the density, shape, and velocity of disperse particles in the flow is considered. Conditions are described under which various modes of stratification of the flow (near-wall, central, intermediate, and multilayer modes) arise. The equilibrium distributions obtained are self-similar; this allows one to compare the behavior of colloidal, highly disperse, coarsely disperse, and coarse-grain systems for various shear velocities and flow widths.

Dependence of residual displacements on the width and depth of compliant fault zones: a 3D study

NASA Astrophysics Data System (ADS)

Kang, J.; Duan, B.

2011-12-01

Compliant fault zones have been detected along active faults by seismic investigations (trapped waves and travel time analysis) and InSAR observations. However, the width and depth extent of compliant fault zones are still under debate in the community. Numerical models of dynamic rupture build a bridge between theories and the geological and geophysical observations. Theoretical 2D plane-strain studies of elastic and inelastic response of compliant fault zones to nearby earthquake have been conducted by Duan [2010] and Duan et al [2010]. In this study, we further extend the experiments to 3D with a focus on elastic response. We are specifically interested in how residual displacements depend on the structure and properties of complaint fault zones, in particular on the width and depth extent. We conduct numerical experiments on various types of fault-zone models, including fault zones with a constant width along depth, with decreasing widths along depth, and with Hanning taper profiles of velocity reduction. . Our preliminary results suggest 1) the width of anomalous horizontal residual displacement is only indicative of the width of a fault zone near the surface, and 2) the vertical residual displacement contains information of the depth extent of compliant fault zones.

Adaptive beam-width control of echolocation sounds by CF-FM bats, Rhinolophus ferrumequinum nippon, during prey-capture flight.

PubMed

Matsuta, Naohiro; Hiryu, Shizuko; Fujioka, Emyo; Yamada, Yasufumi; Riquimaroux, Hiroshi; Watanabe, Yoshiaki

2013-04-01

The echolocation sounds of Japanese CF-FM bats (Rhinolophus ferrumequinum nippon) were measured while the bats pursued a moth (Goniocraspidum pryeri) in a flight chamber. Using a 31-channel microphone array system, we investigated how CF-FM bats adjust pulse direction and beam width according to prey position. During the search and approach phases, the horizontal and vertical beam widths were ±22±5 and ±13±5 deg, respectively. When bats entered the terminal phase approximately 1 m from a moth, distinctive evasive flight by G. pryeri was sometimes observed. Simultaneously, the bats broadened the beam widths of some emissions in both the horizontal (44% of emitted echolocation pulses) and vertical planes (71%). The expanded beam widths were ±36±7 deg (horizontal) and ±30±9 deg (vertical). When moths began evasive flight, the tracking accuracy decreased compared with that during the approach phase. However, in 97% of emissions during the terminal phase, the beam width was wider than the misalignment (the angular difference between the pulse and target directions). These findings indicate that bats actively adjust their beam width to retain the moving target within a spatial echolocation window during the final capture stages.

Electrically Small Microstrip Quarter-Wave Monopole Antennas

NASA Technical Reports Server (NTRS)

Young, W. Robert

2004-01-01

Microstrip-patch-style antennas that generate monopole radiation patterns similar to those of quarter-wave whip antennas can be designed to have dimensions smaller than those needed heretofore for this purpose, by taking advantage of a feed configuration different from the conventional one. The large sizes necessitated by the conventional feed configuration have, until now, made such antennas impractical for frequencies below about 800 MHz: for example, at 200 MHz, the conventional feed configuration necessitates a patch diameter of about 8 ft (.2.4 m) . too large, for example, for mounting on the roof of an automobile or on a small or medium-size aircraft. By making it possible to reduce diameters to between a tenth and a third of that necessitated by the conventional feed configuration, the modified configuration makes it possible to install such antennas in places where they could not previously be installed and thereby helps to realize the potential advantages (concealment and/or reduction of aerodynamic drag) of microstrip versus whip antennas. In both the conventional approach and the innovative approach, a microstrip-patch (or microstrip-patch-style) antenna for generating a monopole radiation pattern includes an electrically conductive patch or plate separated from an electrically conductive ground plane by a layer of electrically insulating material. In the conventional approach, the electrically insulating layer is typically a printed-circuit board about 1/16 in. (.1.6 mm) thick. Ordinarily, a coaxial cable from a transmitter, receiver, or transceiver is attached at the center on the ground-plane side, the shield of the cable being electrically connected to the ground plane. In the conventional approach, the coaxial cable is mated with a connector mounted on the ground plane. The center pin of this connector connects to the center of the coaxial cable and passes through a hole in the ground plane and a small hole in the insulating layer and then connects with the patch above one-third of the radial distance from the center. The modified feed configuration of the innovative approach is an inductive-short-circuit configuration that provides impedance matching and that has been used for many years on other antennas but not on microstrip-style monopole antennas. In this configuration, the pin is connected to both the conductive patch and the ground plane. As before, the shield of the coaxial cable is connected to the ground plane, but now the central conductor is connected to a point on the pin between the ground plane and the conductive plate (see figure). The location of the connection point on the pin is chosen so that together, the inductive short circuit and the conductive plate or patch act as components of a lumped-element resonant circuit that radiates efficiently at the resonance frequency and, at the resonance frequency, has an impedance that matches that of the coaxial cable. It should be noted that the innovative design entails two significant disadvantages. One disadvantage is that the frequency bandwidth for efficient operation is only about 1/20 to 1/15 that of a whip antenna designed for the same nominal frequency. The other disadvantage is that the estimated gain is between 3-1/2 and 4-1/2 dB below that of the whip antenna. However, if an affected radio-communication system used only a few adjacent frequency channels and the design of the components of the system other than the antenna provided adequate power or gain margin, then these disadvantages could be overcome.

Riparian ecotone: A functional definition and delineation for resource assessment

Treesearch

E. S Verry; C. A Dolloff; M. E. Manning

2004-01-01

We propose a geomorphic basis for defining riparian areas using the term: riparian ecotone, discuss how past definitions fall short, and illustrate how a linked sequence of definition, delineation, and riparian sampling are used to accurately assess riparian resources on the ground. Our riparian ecotone is based on the width of the valley (its floodprone area width)...

Effect of Ground Layer Patterns with Slits on Conducted Noise Currents from Printed Circuit Board

NASA Astrophysics Data System (ADS)

Maeno, Tsuyoshi; Unou, Takanori; Ichikawa, Kouji; Fujiwara, Osamu

Electromagnetic disturbances for vehicle-mounted radios can be caused by conducted noise currents that flows out from electronic equipment for vehicles to wire-harnesses. In this paper, for reducing the conducted noise currents from electronic equipment for vehicles, we made a simulation and experiment on how ground patterns affect the noise currents from three-layer printed circuit boards (PCBs) with slit-types and plane-type ground patterns. As a result, we could confirm that slits on a ground pattern allow conducted noise currents to flow out from PCBs to wire-harnesses. For the PCBs with plane-type ground and one of three slit-type patterns, on the other hand, both the simulation and examination showed that resonance phenomena occur at unexpected low-frequencies. A circuit analysis revealed that the above phenomena can be caused by the imbalance of a bridge circuit consisting of the trace circuits on the PCB.

Geosynthetic Reinforcement of Sand-Mat Layer above Soft Ground

PubMed Central

Park, Jong-Beom; Park, Hyun-Soo; Kim, Daehyeon

2013-01-01

In order to improve the bearing capacity of soft ground for the purpose of getting trafficability of construction vehicles, the reinforcement of geosynthetics for sand-mat layers on soft ground has often been used. As the strength of the geosynthetics increases, and the sand-mat system becomes stronger, the bearing capacity of sand-mat systems will be increased. The depths of geosynthetics, reinforced in sand-mat layers, were varied with respect to the width of footing. The tensile strengths of geosynthetics were also varied to evaluate the effect of reinforcement on the bearing capacity of soft ground. The dispersion angles, with varying sand-mat thicknesses, were also determined in consideration of the tensile strength of geosynthetics and the depths of reinforcement installations. The bearing capacity ratios, with the variation of footing width and reinforced embedment depth, were determined for the geosynthetics-only, reinforced soft ground, 1-layer sand-mat system and 2-layer sand-mat system against the non-reinforced soft ground. From the test results of various models, a principle that better explains the concept of geosynthetic reinforcement has been found. On the basis of this principle, a new bearing capacity equation for practical use in the design of geosynthetically reinforced soft ground has been proposed by modifying Yamanouchi’s equation. PMID:28788392

Orbit and sampling requirements: TRMM experience

NASA Technical Reports Server (NTRS)

North, Gerald

1993-01-01

The Tropical Rainfall Measuring Mission (TRMM) concept originated in 1984. Its overall goal is to produce datasets that can be used in the improvement of general circulation models. A primary objective is a multi-year data stream of monthly averages of rain rate over 500 km boxes over the tropical oceans. Vertical distributions of the hydrometers, related to latent heat profiles, and the diurnal cycle of rainrates are secondary products believed to be accessible. The mission is sponsored jointly by the U.S. and Japan. TRMM is an approved mission with launch set for 1997. There are many retrieval and ground truth issues still being studied for TRMM, but here we concentrate on sampling since it is the single largest term in the error budget. The TRMM orbit plane is inclined by 35 degrees to the equator, which leads to a precession of the visits to a given grid box through the local hours of the day, requiring three to six weeks to complete the diurnal cycle, depending on latitude. For sampling studies we can consider the swath width to be about 700 km.

Dissociation dynamics of simple chlorine containing molecules upon resonant Cl K-σ{sup *} excitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bohinc, R., E-mail: rok.bohinc@ijs.si; Bučar, K.; Kavčič, M.

2014-04-28

A theoretical analysis of dissociation dynamics of chlorine K-σ{sup *} core-excited molecules is performed. The potential energy surfaces of HCl, Cl{sub 2}, CH{sub 3}Cl, CH{sub 2}Cl{sub 2}, CHCl{sub 3}, CCl{sub 4}, CFCl{sub 3}, CF{sub 2}Cl{sub 2}, and CF{sub 3}Cl are calculated along the normal vibrational modes of the ground electronic state yielding the widths of the corresponding Franck-Condon distributions. An insight into the potential energy surface of 1st σ{sup *} resonances shows that the initial dissociation dynamics of chloro(fluoro)methanes mainly involves the distancing of the carbon and the core-excited chlorine atom and is practically independent of other atoms in themore » molecule, which is in agreement with the recent experimental findings. The carbon atom pulls out the remaining three atoms shortly after piercing the three-atom plane resulting in a high vibrationally excited state of the fragment if the reconnection time is smaller than the lifetime of the L shell.« less

The comparison of stepping responses following perturbations applied to pelvis during overground and treadmill walking.

PubMed

Zadravec, Matjaž; Olenšek, Andrej; Matjačić, Zlatko

2017-08-09

Treadmills are used frequently in rehabilitation enabling neurologically impaired subjects to train walking while being assisted by therapists. Numerous studies compared walking on treadmill and overground for unperturbed but not also perturbed conditions. The objective of this study was to compare stepping responses (step length, step width and step time) during overground and treadmill walking in a group of healthy subjects where balance assessment robots applied perturbing pushes to the subject's pelvis in sagittal and frontal planes. During walking in both balance assessment robots (overground and treadmill-based) with applied perturbations the stepping responses of a group of seven healthy subjects were assessed with a motion tracking camera. The results show high degree of similarity of stepping responses between overground and treadmill walking for all perturbation directions. Both devices reproduced similar experimental conditions with relatively small standard deviations in the unperturbed walking as well as in perturbed walking. Based on these results we may conclude that stepping responses following perturbations can be studied on an instrumented treadmill where ground reaction forces can be readily assessed which is not the case during perturbed overground walking.

Dual frequency, dual polarized, multi-layered microstrip slot and dipole array antenna

NASA Technical Reports Server (NTRS)

Tulintseff, Ann N. (Inventor)

1995-01-01

An antenna array system is disclosed which uses subarrays of slots and subarrays of dipoles on separate planes. The slots and dipoles respectively are interleaved, which is to say there is minimal overlap between them. Each subarray includes a microstrip transmission line and a plurality of elements extending perpendicular thereto. The dipoles form the transmission elements and the slots form the receive elements. The plane in which the slots are formed also forms a ground plane for the dipoles--hence the feed to the dipole is on the opposite side of this ground plane as the feed to the slots. HPAs are located adjacent the dipoles on one side of the substrate and LNAs are located adjacent the slots on the other side of the substrate. The dipoles and slots are tuned by setting different offsets between each element and the microstrip transmission line.

Monte Carlo Determination of Gamma Ray Exposure from a Homogeneous Ground Plane

DTIC Science & Technology

1990-03-01

A HOMOGENEOUS GROUND PLANE SOURCE THESIS Presented to the Faculty of the School of Engineering of the Air Force Institute of Technology Air University...come from a standard ANISN format library called FEWG1-85. This state-of-the- art cross section library which contains 37 neutron energy groups and 21...purpose. The FEWGl library, a state-of-the- art cross section library developed for the Defense Nuclear Agency con- sisting of 21 gamma-ray enerQj

Absence of effects of an in-plane magnetic field in a quasi-two-dimensional electron system

NASA Astrophysics Data System (ADS)

Brandt, F. T.; Sánchez-Monroy, J. A.

2018-03-01

The dynamics of a quasi-two-dimensional electron system (q2DES) in the presence of a tilted magnetic field is reconsidered employing the thin-layer method. We derive the effective equations for relativistic and nonrelativistic q2DESs. Through a perturbative expansion, we show that while the magnetic length is much greater than the confinement width, the in-plane magnetic field only affects the particle dynamics through the spin. Therefore, effects due to an in-plane magnetic vector potential reported previously in the literature for 2D quantum rings, 2D quantum dots and graphene are fictitious. In particular, the so-called pseudo chiral magnetic effect recently proposed in graphene is not realistic.

Plane Evanescent Waves and Interface Waves

NASA Astrophysics Data System (ADS)

Luppé, F.; Conoir, J. M.; El Kettani, M. Ech-Cherif; Lenoir, O.; Izbicki, J. L.; Duclos, J.; Poirée, B.

The evanescent plane wave formalism is used to obtain the characteristic equation of the normal vibration modes of a plane elastic solid embedded in a perfect fluid. Simple drawings of the real and imaginary parts of complex wave vectors make quite clear the choice of the Riemann sheets on which the roots of the characteristic equation are to be looked for. The generalized Rayleigh wave and the Scholte - Stoneley wave are then described. The same formalism is used to describe Lamb waves on an elastic plane plate immersed in water. The damping, due to energy leaking in the fluid, is shown to be directly given by the projection of evanescence vectors on the interface. Measured values of the damping coefficient are in good agreement with those derived from calculations. The width of the angular resonances associated to Lamb waves or Rayleigh waves is also directly related to this same evanescence vectors projection, as well as the excitation coefficient of a given Lamb wave excited by a plane incident wave. This study shows clearly the strong correlation between the resonance point of view and the wave one in plane interface problems.

Scattering by a groove in an impedance plane

NASA Technical Reports Server (NTRS)

Bindiganavale, Sunil; Volakis, John L.

1993-01-01

An analysis of two-dimensional scattering from a narrow groove in an impedance plane is presented. The groove is represented by a impedance surface and the problem reduces to that of scattering from an impedance strip in an otherwise uniform impedance plane. On the basis of this model, appropriate integral equations are constructed using a form of the impedance plane Green's functions involving rapidly convergent integrals. The integral equations are solved by introducing a single basis representation of the equivalent current on the narrow impedance insert. Both transverse electric (TE) and transverse magnetic (TM) polarizations are treated. The resulting solution is validated by comparison with results from the standard boundary integral method (BIM) and a high frequency solution. It is found that the presented solution for narrow impedance inserts can be used in conjunction with the high frequency solution for the characterization of impedance inserts of any given width.

Orange a-plane InGaN/GaN light-emitting diodes grown on r-plane sapphire substrates.

PubMed

Seo, Yong Gon; Baik, Kwang Hyeon; Song, Hooyoung; Son, Ji-Su; Oh, Kyunghwan; Hwang, Sung-Min

2011-07-04

We report on orange a-plane light-emitting diodes (LEDs) with InGaN single quantum well (SQW) grown on r-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). The peak wavelength and the full-width at half maximum (FWHM) at a drive current of 20mA were 612.2 nm and 72 nm, respectively. The device demonstrated a blue shift in emission wavelength from 614.6 nm at 10 mA to 607.5 nm at 100 mA, representing a net shift of 7.1 nm over a 90 mA range, which is the longest wavelength compared with reported values in nonpolar LEDs. The polarization ratio values obtained from the orange LED varied between 0.36 and 0.44 from 10 to 100mA and a weak dependence of the polarization ratio on the injection current was observed.

In-plane nuclear field formation investigated in single self-assembled quantum dots

NASA Astrophysics Data System (ADS)

Yamamoto, S.; Matsusaki, R.; Kaji, R.; Adachi, S.

2018-02-01

We studied the formation mechanism of the in-plane nuclear field in single self-assembled In0.75Al0.25As /Al0.3Ga0.7As quantum dots. The Hanle curves with an anomalously large width and hysteretic behavior at the critical transverse magnetic field were observed in many single quantum dots grown in the same sample. In order to explain the anomalies in the Hanle curve indicating the formation of a large nuclear field perpendicular to the photo-injected electron spin polarization, we propose a new model based on the current phenomenological model for dynamic nuclear spin polarization. The model includes the effects of the nuclear quadrupole interaction and the sign inversion between in-plane and out-of-plane components of nuclear g factors, and the model calculations reproduce successfully the characteristics of the observed anomalies in the Hanle curves.

Wrinkling instability of an inhomogeneously stretched viscous sheet

NASA Astrophysics Data System (ADS)

Srinivasan, Siddarth; Wei, Zhiyan; Mahadevan, L.

2017-07-01

Motivated by the redrawing of hot glass into thin sheets, we investigate the shape and stability of a thin viscous sheet that is inhomogeneously stretched in an imposed nonuniform temperature field. We first determine the associated base flow by solving the long-time-scale stretching flow of a flat sheet as a function of two dimensionless parameters: the normalized stretching velocity α and a dimensionless width of the heating zone β . This allows us to determine the conditions for the onset of an out-of-plane wrinkling instability stated in terms of an eigenvalue problem for a linear partial differential equation governing the displacement of the midsurface of the sheet. We show that the sheet can become unstable in two regions that are upstream and downstream of the heating zone where the minimum in-plane stress is negative. This yields the shape and growth rates of the most unstable buckling mode in both regions for various values of the stretching velocity and heating zone width. A transition from stationary to oscillatory unstable modes is found in the upstream region with increasing β , while the downstream region is always stationary. We show that the wrinkling instability can be entirely suppressed when the surface tension is large enough relative to the magnitude of the in-plane stress. Finally, we present an operating diagram that indicates regions of the parameter space that result in a required outlet sheet thickness upon stretching while simultaneously minimizing or suppressing the out-of-plane buckling, a result that is relevant for the glass redraw method used to create ultrathin glass sheets.

Turbulent boundary layers over nonstationary plane boundaries

NASA Technical Reports Server (NTRS)

Roper, A. T.; Gentry, G. L., Jr.

1978-01-01

Methods of predicting integral parameters and skin friction coefficients of turbulent boundary layers developing over moving ground planes were evaluated. The three methods evaluated were: relative integral parameter method; relative power law method; and modified law of the wall method.

I-V characteristics of in-plane and out-of-plane strained edge-hydrogenated armchair graphene nanoribbons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cartamil-Bueno, S. J., E-mail: s.j.cartamilbueno@tudelft.nl, E-mail: rbolivar@ugr.es; Rodríguez-Bolívar, S., E-mail: s.j.cartamilbueno@tudelft.nl, E-mail: rbolivar@ugr.es

2015-06-28

The effects of tensile strain on the current-voltage (I-V) characteristics of hydrogenated-edge armchair graphene nanoribbons are investigated by using DFT theory. The strain is introduced in two different ways related to the two types of systems studied in this work: in-plane strained systems (A) and out-of-plane strained systems due to bending (B). These two kinds of strain lead to make a distinction among three cases: in-plane strained systems with strained electrodes (A1) and with unstrained electrodes (A2), and out-of-plane homogeneously strained systems with unstrained, fixed electrodes (B). The systematic simulations to calculate the electronic transmission between two electrodes were focusedmore » on systems of 8 and 11 dimers in width. The results show that the differences between cases A2 and B are negligible, even though the strain mechanisms are different: in the plane case, the strain is uniaxial along its length; while in the bent case, the strain is caused by the arc deformation. Based on the study, a new type of nanoelectromechanical system solid state switching device is proposed.« less

High Accuracy Monocular SFM and Scale Correction for Autonomous Driving.

PubMed

Song, Shiyu; Chandraker, Manmohan; Guest, Clark C

2016-04-01

We present a real-time monocular visual odometry system that achieves high accuracy in real-world autonomous driving applications. First, we demonstrate robust monocular SFM that exploits multithreading to handle driving scenes with large motions and rapidly changing imagery. To correct for scale drift, we use known height of the camera from the ground plane. Our second contribution is a novel data-driven mechanism for cue combination that allows highly accurate ground plane estimation by adapting observation covariances of multiple cues, such as sparse feature matching and dense inter-frame stereo, based on their relative confidences inferred from visual data on a per-frame basis. Finally, we demonstrate extensive benchmark performance and comparisons on the challenging KITTI dataset, achieving accuracy comparable to stereo and exceeding prior monocular systems. Our SFM system is optimized to output pose within 50 ms in the worst case, while average case operation is over 30 fps. Our framework also significantly boosts the accuracy of applications like object localization that rely on the ground plane.

A new planar broadband antenna based on meandered line loops for portable wireless communication devices

NASA Astrophysics Data System (ADS)

Alibakhshi-Kenari, Mohammad; Naser-Moghadasi, Mohammad; Sadeghzadeh, R. A.; Virdee, Bal S.; Limiti, Ernesto

2016-07-01

This article presents the design of a novel planar antenna structure comprising two pairs of interconnected meandered line loops that are grounded to a truncated T-shaped ground plane through two via holes. The T-shaped ground plane is used as a reflector to enhance the performance of the antenna. The resulting antenna is compact occupying an area of 38.5 × 36.6 mm2 (0.070λo × 0.067λo), where free-space wavelength is 550 MHz. The antenna radiates omnidirectionally in the E plane across its operational bandwidth (550 MHz to 3.85 GHz) with peak gain and efficiency of 5.5 dBi and 90.1%, respectively, at 2.35 GHz and reflection coefficient better than -10 dB. These characteristics make the antenna suitable for numerous applications, in particular, JCDMA, UHF RFID, GSM 900, GPS, KPCS, DCS, IMT-2000, WiMAX, WiFi, and Bluetooth.

Electromagnetic scattering analysis of a three-dimensional-cavity-backed aperture in an infinite ground plane using a combined finite element method/method of moments approach

NASA Technical Reports Server (NTRS)

Reddy, C. J.; Deshpande, Manohar D.; Cockrell, C. R.; Beck, F. B.

1995-01-01

A combined finite element method/method of moments (FEM/MoM) approach is used to analyze the electromagnetic scattering properties of a three-dimensional-cavity-backed aperture in an infinite ground plane. The FEM is used to formulate the fields inside the cavity, and the MoM (with subdomain bases) in both spectral and spatial domains is used to formulate the fields above the ground plane. Fields in the aperture and the cavity are solved using a system of equations resulting from the combination of the FEM and the MoM. By virtue of the FEM, this combined approach is applicable to all arbitrarily shaped cavities with inhomogeneous material fillings, and because of the subdomain bases used in the MoM, the apertures can be of any arbitrary shape. This approach leads to a partly sparse and partly full symmetric matrix, which is efficiently solved using a biconjugate gradient algorithm. Numerical results are presented to validate the analysis.

Circularly polarized triple band glass shaped monopole patch antenna with metallic reflector for bluetooth & wireless applications

NASA Astrophysics Data System (ADS)

Jangid, K. G.; Choudhary, N.; Jain, P.; Sharma, B. R.; Saini, J. S.; Kulhar, V. S.; Bhatnagar, D.

2016-03-01

This paper presents the design and performance of strip line fed glass shaped monopole patch antenna having with overall size 30mm × 30 mm × 1.59 mm. In the patch; an eight shaped slot and in the ground plane an eight shaped ring are introduced. A metallic ground plane is also introduced at appropriate location beneath the ground plane. The proposed antenna is simulated by applying CST Microwave Studio simulator. Antenna provides circularly polarized radiations, triple broad impedance bandwidth of 203MHz (2.306GHz to 2.510GHz), 42MHz (2.685GHz to 2.757GHz) & GHz (3.63 GHz to 6.05 GHz), high flat gain (close to 5dBi) and good radiation properties in the desired frequency range. This antenna may be a very useful tool for 2.45GHz Bluetooth communication band as well as for 2.4GHz/5.2 GHz /5.8 GHz WLAN bands & 3.7GHz/5.5 GHz Wi-Max bands.

On the long range propagation of sound over irregular terrain

NASA Technical Reports Server (NTRS)

Howe, M. S.

1984-01-01

The theory of sound propagation over randomly irregular, nominally plane terrain of finite impedance is discussed. The analysis is an extension of the theory of coherent scatter originally proposed by Biot for an irregular rigid surface. It combines Biot's approach, wherein the surface irregularities are modeled by a homogeneous distribution of hemispherical bosses, with more conventional analyses in which the ground is modeled as a smooth plane of finite impedance. At sufficiently low frequencies the interaction of the surface irregularities with the nearfield of a ground-based source leads to the production of surface waves, which are effective in penetrating the ground shadow zone predicted for a smooth surface of the same impedance.

The role of atmospheric shear, turbulence and a ground plane on the dissipation of aircraft vortex wakes

NASA Technical Reports Server (NTRS)

Bilanin, A. J.; Teske, M. E.; Hirsh, J. E.

1978-01-01

Enhanced dispersion of two-dimensional trailed vortex pairs within simplified neutral atmospheric backgrounds is studied numerically for three conditions: when the pair is imbedded in a constant turbulent bath (constant dissipation); when the pair is subjected to a mean cross-wind shear; and when the pair is near the ground. Turbulent transport is modeled using second-order closure turbulent transport theory. The turbulent background fields are constructed using a superequilibrium approximation. The computed results allow several general conclusions to be drawn with regard to the reduction in circulation of the vortex pair and the rolling moment induced on a following aircraft: (1) the rate of decay of a vortex pair increases with increasing background dissipation rate; (2) cross-wind shear disperses the vortex whose vorticity is opposite to the background; and (3) the proximity of a ground plane reduces the hazard of the pair by scrubbing. The phenomenon of vortex bounce is explained in terms of secondary vorticity produced at the ground plane. Qualitative comparisons are made with available experimental data, and inferences of these results upon the persistence of aircraft trailing vortices are discussed.

Cephalometric skeletal evaluation of patients with Incontinentia Pigmenti

PubMed Central

Maahs, Marcia Angelica Peter; Kiszewski, Ana Elisa; Rosa, Rafael Fabiano Machado; Maria, Fernanda Diffini Santa; Prates, Frederico Ballvé; Zen, Paulo Ricardo Gazzola

2014-01-01

Purpose The aim of this study was to evaluate the skeletal characteristics of patients with the rare genetic disease of Incontinentia Pigmenti, by lateral cephalometric analysis on the antero-posterior plane and by frontal cephalometric analysis on the horizontal plane. Methods Lateral skeletal cephalometric analyses were performed according to Steiner for evaluation of antero-posterior direction, and frontal skeletal cephalometric analyses according to Ricketts for evaluation of horizontal direction in 9 patients with IP. Left and right facial widths at the level of the zygomatic arch were also evaluated. The Student t-test was used for paired to a 5% level of significance data. Results The lateral skeletal cephalometric findings were not statistically significant, but the Class II was the most frequent finding (44.4%), followed by Class III (33.3%) and Class I (22.2%). The right maxillo-mandibular width was significantly lower than normal values, and the right facial width was significantly higher than the left, at the level of the zygomatic arch. Conclusions Patients with IP showed more skeletal discrepancies of Class II and III than Class I malocclusion, and had significant horizontal facial skeletal asymmetries. This should alert health professionals to route these patients for orthodontic assessment and possible therapeutic interventions. However, larger samples are needed to better elucidate if these cephalometric findings can be specifically related to IP. PMID:25737924

On the granular fingering instability: controlled triggering in laboratory experiments and numerical simulations

NASA Astrophysics Data System (ADS)

Vriend, Nathalie; Tsang, Jonny; Arran, Matthew; Jin, Binbin; Johnsen, Alexander

2017-11-01

When a mixture of small, smooth particles and larger, coarse particles is released on a rough inclined plane, the initial uniform front may break up in distinct fingers which elongate over time. This fingering instability is sensitive to the unique arrangement of individual particles and is driven by granular segregation (Pouliquen et al., 1997). Variability in initial conditions create significant limitations for consistent experimental and numerical validation of newly developed theoretical models (Baker et al., 2016) for finger formation. We present an experimental study using a novel tool that sets the initial fingering width of the instability. By changing this trigger width between experiments, we explore the response of the avalanche breakup to perturbations of different widths. Discrete particle simulations (using MercuryDPM, Thornton et al., 2012) are conducted under a similar setting, reproducing the variable finger width, allowing validation between experiments and numerical simulations. A good agreement between simulations and experiments is obtained, and ongoing theoretical work is briefly introduced. NMV acknowledges the Royal Society Dorothy Hodgkin Research Fellowship.

Quality of terrestrial data derived from UAV photogrammetry: a case study of the Hetao irrigation district in northern China

NASA Astrophysics Data System (ADS)

Zhang, Hongming; Baartman, Jantiene E. M.; Yang, Xiaomei; Gai, Lingtong; Geissen, Violette

2017-04-01

Most crops in northern China are irrigated, but the topography affects water use, soil erosion, runoff and yields,. Technologies for collecting high-resolution topographic data are essential for adequately assessing these effects. Ground surveys and techniques of light detection and ranging have good accuracy, but data acquisition can be time-consuming and expensive for large catchments. Recent rapid technological development has provided new, flexible, high-resolution methods for collecting topographic data, such as photogrammetry using unmanned aerial vehicles (UAVs). The accuracy of UAV photogrammetry for generating high-resolution digital elevation models (DEMs) and for determining the width of irrigation channels, however, has not been assessed. We used a fixed-wing UAV for collecting high-resolution (0.15 m) topographic data for the Hetao irrigation district, the third largest irrigation district in China. We surveyed 112 ground checkpoints (GCPs) using a real-time kinematic global positioning system to evaluate the accuracy of the DEMs and channel widths. A comparison of manually measured channel widths with the widths derived from the DEMs indicated that the DEM-derived widths had vertical and horizontal root mean square errors of 13.0 and 7.9 cm, respectively. UAV photogrammetric data can thus be used for land surveying, digital mapping, calculating channel capacity, monitoring crops, and predicting yields, with the advantages of economy, speed, and ease.

Microplasma generating array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopwood, Jeffrey A.; Wu, Chen; Hoskinson, Alan R.

A microplasma generator includes first and second conductive resonators disposed on a first surface of a dielectric substrate. The first and second conductive resonators are arranged in line with one another with a gap defined between a first end of each resonator. A ground plane is disposed on a second surface of the dielectric substrate and a second end of each of the first and second resonators is coupled to the ground plane. A power input connector is coupled to the first resonator at a first predetermined distance from the second end chosen as a function of the impedance ofmore » the first conductive resonator. A microplasma generating array includes a number of resonators in a dielectric material substrate with one end of each resonator coupled to ground. A micro-plasma is generated at the non-grounded end of each resonator. The substrate includes a ground electrode and the microplasmas are generated between the non-grounded end of the resonator and the ground electrode. The coupling of each resonator to ground may be made through controlled switches in order to turn each resonator off or on and therefore control where and when a microplasma will be created in the array.« less

Study of electrode pattern design for a CZT-based PET detector.

PubMed

Gu, Y; Levin, C S

2014-06-07

We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3D positioning cadmium zinc telluride photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 to ~127.5 ns full width at half maximum (FWHM) for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips' weighting functions, which indicated a stronger 'small pixel' effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 to -80 V w.r.t. the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 versus 100 µm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns.

Ultrasonic alignment of bio-functionalized magnetic beads and live cells in PDMS micro-fluidic channel.

PubMed

Islam, Afroja T; Siddique, Ariful H; Ramulu, T S; Reddy, Venu; Eu, Young-Jae; Cho, Seung Hyun; Kim, CheolGi

2012-12-01

In this work, we demonstrated the alignment of polystyrene latex microspheres (diameter of 1 ~45 μm), bio-functionalized superparamagnetic beads (diameter 2.8 μm), and live cells (average diameter 1 ~2 μm) using an ultrasonic standing wave (USW) in a PDMS microfluidic channel (330 μm width) attached on a Si substrate for bio-medical applications. To generate a standing wave inside the channel, ultrasound of 2.25 MHz resonance frequency (for the channel width) was applied by two ultrasound transducers installed at both sides of the channel which caused the radiation force to concentrate the micro-particles at the single pressure nodal plane of USW. By increasing the frequency to the next resonance condition of the channel, the particles were concentrated in dual nodal planes. Migration time of the micro-particles towards the single nodal plane was recorded as 108 s, 17 s, and 115 s for polystyrene particles of 2 μm diameter, bio-functionalized magnetic beads, and live cells, respectively. These successful alignments of the bio-functionalized magnetic beads along the desired part of the channel can enhance the performance of a sensor which is applicable for the bio-hybrid system and the alignment of live cells without any damage can be used for sample pre-treatment for the application of lab-on-a-chip type bioassays.

Formation of chocolate-tablet boudins: Results from scaled analogue models

NASA Astrophysics Data System (ADS)

Zulauf, J.; Zulauf, G.; Göttlich, J.; Peinl, M.

2014-11-01

We used power-law viscous plasticine as a rock analogue to simulate chocolate tablet boudinage of rocks undergoing dislocation creep. A competent plasticine layer, oriented perpendicular to the main shortening direction, Z, underwent two phases of plane strain in a weaker plasticine matrix, with the principal stretching axis, X, and the axis of no-change, Y, replacing each other from the first to the second phase. In each phase of plane strain, boudinage was controlled by an initial phase of viscous necking followed by extension fracture along the neck domain. Increase in the magnitude of finite strain (e) and decrease in layer thickness (Hi) result in a decrease in the boudin width (Wa) and an increase in the number of boudins (N). Given the viscosity ratio between layer and matrix (m) is higher than ca. 5, the number of boudins decreases and the boudin width increases with increasing values of m. An unexpected result of the present study is that in each experiment, the number of boudins was significantly higher during the second phase of plane strain. This difference should be related to additional drag of the matrix plasticine on the stiff layer in the neck domains formed during the first phase of boudinage. The aspect ratio of the second generation of boudins (Wd = Wa/Hi) is compatible with aspect ratios of natural boudins and with aspect ratios calculated using analytical solutions.

Changes in foot and shank coupling due to alterations in foot strike pattern during running.

PubMed

Pohl, Michael B; Buckley, John G

2008-03-01

Determining if and how the kinematic relationship between adjacent body segments changes when an individual's gait pattern is experimentally manipulated can yield insight into the robustness of the kinematic coupling across the associated joint(s). The aim of this study was to assess the effects on the kinematic coupling between the forefoot, rearfoot and shank during ground contact of running with alteration in foot strike pattern. Twelve subjects ran over-ground using three different foot strike patterns (heel strike, forefoot strike, toe running). Kinematic data were collected of the forefoot, rearfoot and shank, which were modelled as rigid segments. Coupling at the ankle-complex and midfoot joints was assessed using cross-correlation and vector coding techniques. In general good coupling was found between rearfoot frontal plane motion and transverse plane shank rotation regardless of foot strike pattern. Forefoot motion was also strongly coupled with rearfoot frontal plane motion. Subtle differences were noted in the amount of rearfoot eversion transferred into shank internal rotation in the first 10-15% of stance during heel strike running compared to forefoot and toe running, and this was accompanied by small alterations in forefoot kinematics. These findings indicate that during ground contact in running there is strong coupling between the rearfoot and shank via the action of the joints in the ankle-complex. In addition, there was good coupling of both sagittal and transverse plane forefoot with rearfoot frontal plane motion via the action of the midfoot joints.

Aircraft wake vortex transport model

DOT National Transportation Integrated Search

1974-03-31

A wake vortex transport model has been developed which includes the effects of wind and wind : shear, buoyancy, mutual and self-induction, ground plane interaction, viscous decay, finite core : and Crow instability effects. Photographic and ground-wi...

Reduced model simulations of the scrape-off-layer heat-flux width and comparison with experiment

DOE PAGES

Myra, J. R.; Russell, D. A.; D’Ippolito, D. A.; ...

2011-01-01

Reduced model simulations of turbulence in the edge and scrape-off-layer (SOL) region of a spherical torus or tokamak plasma are employed to address the physics of the scrape-off-layer heat flux width. The simulation model is an electrostatic two-dimensional fluid turbulence model, applied in the plane perpendicular to the magnetic field at the outboard midplane of the torus. The model contains curvature-driven-interchange modes, sheath losses, and both perpendicular turbulent diffusive and convective (blob) transport. These transport processes compete with classical parallel transport to set the SOL width. Midplane SOL profiles of density, temperature and parallel heat flux are obtained from themore » simulation and compared with experimental results from the National Spherical Torus Experiment (NSTX) to study the scaling of the heat flux width with power and plasma current. It is concluded that midplane turbulence is the main contributor to the SOL heat flux width for the low power H-mode discharges studied, while additional physics is required to explain the plasma current scaling of the SOL heat flux width observed experimentally in higher power discharges. Intermittent separatrix spanning convective cells are found to be the main mechanism that sets the near-SOL width in the simulations. The roles of sheared flows and blob trapping vs. emission are discussed.« less

Flow resistivity instrument in the earth

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor)

1984-01-01

Method and apparatus for making in-situ measurements of flow resistivity on the Earth's ground surface. The novel feature of the invention is two concentric cylinders, 22 and 23, inserted into the ground surface 24 with a measured pressure 21 applied to the surface inside the inner cylinder 22. The outer cylinder 23 vents a plane B-B beneath the surface to the atmosphere through an air space 28. The flow to the inner cylinder is measured (16) thereby indicating the flow from the surface to the plane beneath the surface.

WMSA for wireless communication applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vats, Monika; Agarwal, Alok, E-mail: alokagarwal26@yahoo.com; Kumar, Ravindra

2016-03-09

Modified rectangular compact microstrip patch antenna having finite ground plane is proposed in this paper. Wideband Microstrip Antenna (WMSA) is achieved by corner cut and inserting air gaps inside the edges of the radiating patch having finite ground plane. The obtained impedance bandwidth for 10 dB return loss for the operating frequency f{sub 0} = 2.09 GHz is 28.7 % (600 MHz), which is very high as compared to the bandwidth obtained for the conventional microstrip antenna. Compactness with wide bandwidth of this antenna is practically useful for the wireless communication systems.

Magnetic anisotropy and chirality of frustrated Cr nanostructures on Au(1 1 1)

NASA Astrophysics Data System (ADS)

Balogh, L.; Udvardi, L.; Szunyogh, L.

2014-10-01

By using a fully relativistic embedded cluster Green's function technique we investigated the magnetic anisotropy properties of four different compact Cr trimers (equilateral triangles) and Cr mono-layers deposited on the Au(1 1 1) surface in both fcc and hcp stackings. For all trimers the magnetic ground state was found to be a frustrated 120° Néel configuration. Applying global spin rotations to the magnetic ground state, predictions of an appropriate second order spin Hamiltonian were reproduced with high accuracy by first principles calculations. For the Cr trimers with adjacent Au atoms in similar geometry, we obtained similar values for the in-plane and out-of-plane anisotropy parameters, however, the Dzyaloshinskii-Moriya (DM) interactions appeared to differ remarkably. For two kinds of trimers we found an unconventional magnetic ground state showing 90° in-the-plane rotation with respect to the high symmetry directions. Due to higher symmetry, the in-plane anisotropy term was missing for the mono-layers and distinctly different DM interactions were obtained for the different stackings. The chiral degeneracy of the Néel configurations was lifted by an energy less than 2 meV for the trimers, while this value increased up to about 15 meV per 3 Cr atoms for the hcp packed mono-layer.

Molecular dynamics simulations of collagen adsorption onto grooved rutile surface: the effects of groove width.

PubMed

Chen, Mingjun; Zheng, Ting; Wu, Chunya; Xing, Cheng

2014-09-01

The early adsorption stages of collagen onto nano-grooved rutile surface without hydroxylation were studied using molecular dynamics and steered MD simulations. On the basis of plane rutile (110), two kinds of models have been adopted: single groove and parallel grooves along [1-11] crystal orientation with various width dimensions. Initially, collagens were parallel or perpendicular to the groove orientation, respectively, in order to investigate the influence of groove width on collagen adsorption. The simulation result suggests that surface grooves could exert a strong effect on collagen adsorption: when collagen was parallel to the groove direction, adsorption was favored if the groove width matched well with the dimension of collagen. However, adsorption strength may decrease as the groove width expanded. As for the condition of collagen perpendicular to the groove orientation, collagen was difficult to bend and insert into grooves in the free adsorption procedure. But the steered MD simulation results reveal that more energy was consumed for collagen to insert into narrower grooves which may be interpreted as strong barrier for adsorption. We believe that adsorption will be favored if appropriate dimension match between dimension of collagen and the groove width was approached. Copyright © 2014 Elsevier B.V. All rights reserved.

Apodization of two-dimensional pupils with aberrations

NASA Astrophysics Data System (ADS)

Reddy, Andra Naresh Kumar; Hashemi, Mahdieh; Khonina, Svetlana Nikolaevna

2018-06-01

The technique proposed to enhance the resolution of the point spread function (PSF) of an optical system underneath defocussing and spherical aberrations. The method of approach is based on the amplitude and phase masking in a ring aperture for modifying the light intensity distribution in the Gaussian focal plane (YD = 0) and in the defocussed planes (YD= π and YD= 2π ). The width of the annulus modifies the distribution of the light intensity in the side lobes of the resultant PSF. In the presence of an asymmetry in the phase of the annulus, the Hanning amplitude apodizer [cos(π β ρ )] employed in the pupil function can modify the spatial distribution of light in the maximum defocussed plane ({Y}D = 2π ), results in PSF with improved resolution.

Determining The Plane of The Kuiper Belt with OSSOS

NASA Astrophysics Data System (ADS)

Van Laerhoven, Christa; Kavelaars, J. J.; Volk, Kathryn; Gladman, Brett; Petit, Jean-Marc

2018-04-01

We present the OSSOS-based measurement of the semi-major axes dependent orientation of the Kuiper Belt plane. A Kuiper Belt object's (KBO's) inclination can be broken down into a forced component and a free component. The inclination and longitude of ascending node of the forced inclination define the 'forced plane,' the plane about which the KBO's inclination will precess. Secular theory predicts that this forced plane should depend on semi-major axis. For example, the nu18 secular resonance should create a significant warp in the forced planet near 40.5 au (Chiang and Choi 2008). Not predicted by secular theory is a warp in the distant Kuiper Belt (semi-major axes greater than 50 au) seen by Volk and Malhotra 2016 using KBOs from the Minor Planet Catalog. We investigate what the inclination distribution is for objects beyond Neptune as a function of semi-major axis using the OSSOS characterized sample. Through use of the OSSOS survey simulator we test various underlying orbital distributions and compare how the survey would have observed those populations to the actual observed sample. In particular, we test various widths for the inclination distribution about various local forcing planes for the kernel, stirred, and hot classical Kuiper Belt. We find that the forced plane in matches well with the expected forced plane from secular theory. Through most of the main Kuiper Belt (between the 3:2 and 2:1 resonances), we can reject both the ecliptic plane and the invariable plane as the true forced plane. Only as the expected secularly forced plane approaches the invariable plane does the invariable plane become non-rejectable. In the outer Kuiper Belt we reject the nominal mean-plane measured by Volk and Malhotra, but smaller warps are still allowed by the data.

Gated strip proportional detector

DOEpatents

Morris, C.L.; Idzorek, G.C.; Atencio, L.G.

1985-02-19

A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10/sup 6/. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

Gated strip proportional detector

DOEpatents

Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.

1987-01-01

A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10.sup.6. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

16 CFR 1512.16 - Requirements for reflectors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 1512.16 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT... vehicle headlamps. The use of reflector combinations off the center plane of the bicycle (defined in...) Front reflector. The reflector or mount shall not contact the ground plane when the bicycle is resting...

Structural anisotropic properties of a-plane GaN epilayers grown on r-plane sapphire by molecular beam epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lotsari, A.; Kehagias, Th.; Katsikini, M.

2014-06-07

Heteroepitaxial non-polar III-Nitride layers may exhibit extensive anisotropy in the surface morphology and the epilayer microstructure along distinct in-plane directions. The structural anisotropy, evidenced by the “M”-shape dependence of the (112{sup ¯}0) x-ray rocking curve widths on the beam azimuth angle, was studied by combining transmission electron microscopy observations, Raman spectroscopy, high resolution x-ray diffraction, and atomic force microscopy in a-plane GaN epilayers grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PAMBE). The structural anisotropic behavior was attributed quantitatively to the high dislocation densities, particularly the Frank-Shockley partial dislocations that delimit the I{sub 1} intrinsic basal stacking faults,more » and to the concomitant plastic strain relaxation. On the other hand, isotropic samples exhibited lower dislocation densities and a biaxial residual stress state. For PAMBE growth, the anisotropy was correlated to N-rich (or Ga-poor) conditions on the surface during growth, that result in formation of asymmetric a-plane GaN grains elongated along the c-axis. Such conditions enhance the anisotropy of gallium diffusion on the surface and reduce the GaN nucleation rate.« less

Zero-internal fields in nonpolar InGaN/GaN multi-quantum wells grown by the multi-buffer layer technique.

PubMed

Song, Hooyoung; Kim, Jin Soak; Kim, Eun Kyu; Seo, Yong Gon; Hwang, Sung-Min

2010-04-02

The potential of nonpolar a-plane InGaN/GaN multi-quantum wells (MQWs), which are free from a strong piezoelectric field, was demonstrated. An a-GaN template grown on an r-plane sapphire substrate by the multi-buffer layer technique showed high structural quality with an omega full width at half maximum value along the c-axis of 418 arcsec obtained from high-resolution x-ray diffraction analysis. From barrier analysis by deep level transient spectroscopy, it appeared that a-plane InGaN/GaN MQWs can solve the efficiency droop problem as they have a lower electron capture barrier than the c-plane sample. The peak shift of the temperature-dependent photoluminescence signal for the nonpolar InGaN/GaN MQWs was well fitted by Varshni's empirical equation with zero-internal fields. A high photoluminescence efficiency of 0.27 from this sample also showed that nonpolar MQWs can be the key factor to solve the efficiency limitation in conventional c-plane GaN based light emitting diodes.

Time domain analysis of thin-wire antennas over lossy ground using the reflection-coefficient approximation

NASA Astrophysics Data System (ADS)

FernáNdez Pantoja, M.; Yarovoy, A. G.; Rubio Bretones, A.; GonzáLez GarcíA, S.

2009-12-01

This paper presents a procedure to extend the methods of moments in time domain for the transient analysis of thin-wire antennas to include those cases where the antennas are located over a lossy half-space. This extended technique is based on the reflection coefficient (RC) approach, which approximates the fields incident on the ground interface as plane waves and calculates the time domain RC using the inverse Fourier transform of Fresnel equations. The implementation presented in this paper uses general expressions for the RC which extend its range of applicability to lossy grounds, and is proven to be accurate and fast for antennas located not too near to the ground. The resulting general purpose procedure, able to treat arbitrarily oriented thin-wire antennas, is appropriate for all kind of half-spaces, including lossy cases, and it has turned out to be as computationally fast solving the problem of an arbitrary ground as dealing with a perfect electric conductor ground plane. Results show a numerical validation of the method for different half-spaces, paying special attention to the influence of the antenna to ground distance in the accuracy of the results.

Spectral Assignments and Analysis of the Ground State of Nitromethane in High-Resolution FTIR Synchrotron Spectra

NASA Astrophysics Data System (ADS)

Twagirayezu, Sylvestre; Billinghurst, Brant E.; May, Tim E.; Dawadi, Mahesh B.; Perry, David S.

2014-06-01

The Fourier Transform infrared spectra of CH3NO2, have been recorded, in the 400-950 wn spectral region, at a resolution of 0.00096 wn, using the Far-Infrared Beamline at Canadian Light Source. The observed spectra contain four fundamental vibrations: the NO2 in-plane rock (475.2 wn), the NO2 out-of-plane rock (604.9 wn), the NO2 symmetric bend (657.1 wn), and the CN-stretch (917.2 wn). For the lowest torsional state of CN-stretch and NO2 in-plane rock, transitions involving quantum numbers, " = 0; " {≤ 50} and {_a}" {≤ 10}, have been assigned with the aid of an automated ground state combination difference program together with a traditional Loomis Wood approach Ground state combination differences derived from more than 2100 infrared transitions have been fit with the six-fold torsion-rotation program developed by Ilyushin et al. Additional sextic and octic centrifugal distortion parameters are derived for the ground vibrational state. C. F. Neese., An Interactive Loomis-Wood Package, V2.0, {56th},OSU Interanational Symposium on Molecular Spectroscopy (2001). V. V. Ilyushin, Z. Kisiel, L. Pszczolkowski, H. Mader, and J. T. Hougen, J. Mol. Spectrosc., 259, 26, (2010).

Collins Aerodyne VTOL aircraft investigations

NASA Image and Video Library

1960-01-11

Collins Aerodyne vertical take-off and landing (VTOL) aircraft investigations. Ground plane support system. 3/4 front view. Dave Koening (from Collins Aerodyne) in photo. Mounted on variable height struts, ground board system, zero degree angle of attack. 01/11/1960

Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teperik, Tatiana V., E-mail: tatiana.teperik@u-psud.fr; Donostia International Physics Center, Aptdo. 1072, 20080 San Sebastian; Lustrac, André de

We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiationmore » scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.« less

Circularly polarized triple band glass shaped monopole patch antenna with metallic reflector for bluetooth & wireless applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jangid, K. G.; Kulhar, V. S.; Choudhary, N.

This paper presents the design and performance of strip line fed glass shaped monopole patch antenna having with overall size 30mm × 30 mm × 1.59 mm. In the patch; an eight shaped slot and in the ground plane an eight shaped ring are introduced. A metallic ground plane is also introduced at appropriate location beneath the ground plane. The proposed antenna is simulated by applying CST Microwave Studio simulator. Antenna provides circularly polarized radiations, triple broad impedance bandwidth of 203MHz (2.306GHz to 2.510GHz), 42MHz (2.685GHz to 2.757GHz) & GHz (3.63 GHz to 6.05 GHz), high flat gain (close to 5dBi) and good radiationmore » properties in the desired frequency range. This antenna may be a very useful tool for 2.45GHz Bluetooth communication band as well as for 2.4GHz/5.2 GHz /5.8 GHz WLAN bands & 3.7GHz/5.5 GHz Wi-Max bands.« less

The Neuro-Mechanical Processes That Underlie Goal-Directed Medio-Lateral APA during Gait Initiation.

PubMed

Honeine, Jean-Louis; Schieppati, Marco; Crisafulli, Oscar; Do, Manh-Cuong

2016-01-01

Gait initiation (GI) involves passing from bipedal to unipedal stance. It requires a rapid movement of the center of foot pressure (CoP) towards the future swing foot and of the center of mass (CoM) in the direction of the stance foot prior to the incoming step. This anticipatory postural adjustment (APA) allows disengaging the swing leg from the ground and establishing favorable conditions for stepping. This study aimed to describe the neuro-mechanical process that underlies the goal-directed medio-lateral (ML) APA. We hypothesized that controlled knee flexion of the stance leg contributes to the initial ML displacement of the CoP and to the calibration of the first step. Fourteen subjects initiated gait starting from three different initial stance widths of 15 cm (Small), 30 cm (Medium), and 45 cm (Large). Optoelectronic, force platform and electromyogram (EMG) measurements were performed. During APA, soleus activity diminished bilaterally, while tibialis anterior (TA) activity increased, more so in the stance leg than in the swing leg, and to a larger extent with increasing initial stance width. Knee flexion of the stance leg was observed during APA and correlated with the ML CoP displacement towards the swing leg. ML CoP and CoM displacements during APA increased with increasing stance width. The activity of stance-leg TA was correlated with the degree of knee flexion. Swing-leg tensor fasciae latae (TFL) was also active during APA. Across subjects, when stance-leg tibialis activity was low, TFL activity was large and vice versa. The modulation of the ML CoP position during APA allowed the gravity-driven torque to place the CoM just lateral to the stance foot during step execution. Accordingly, the gravity-driven torque, the ML CoM velocity during step execution, and the step width at foot contact (FC) were lower in the Small and greater in the Large condition. Consequently, the position of the stepping foot at FC remained close to the sagittal plane in all three conditions. Conclusively, coordinated activation of hip abductors and ankle dorsiflexors during APA displaces the CoP towards the swing leg, and sets the contact position for the swing foot.

The Neuro-Mechanical Processes That Underlie Goal-Directed Medio-Lateral APA during Gait Initiation

PubMed Central

Honeine, Jean-Louis; Schieppati, Marco; Crisafulli, Oscar; Do, Manh-Cuong

2016-01-01

Gait initiation (GI) involves passing from bipedal to unipedal stance. It requires a rapid movement of the center of foot pressure (CoP) towards the future swing foot and of the center of mass (CoM) in the direction of the stance foot prior to the incoming step. This anticipatory postural adjustment (APA) allows disengaging the swing leg from the ground and establishing favorable conditions for stepping. This study aimed to describe the neuro-mechanical process that underlies the goal-directed medio-lateral (ML) APA. We hypothesized that controlled knee flexion of the stance leg contributes to the initial ML displacement of the CoP and to the calibration of the first step. Fourteen subjects initiated gait starting from three different initial stance widths of 15 cm (Small), 30 cm (Medium), and 45 cm (Large). Optoelectronic, force platform and electromyogram (EMG) measurements were performed. During APA, soleus activity diminished bilaterally, while tibialis anterior (TA) activity increased, more so in the stance leg than in the swing leg, and to a larger extent with increasing initial stance width. Knee flexion of the stance leg was observed during APA and correlated with the ML CoP displacement towards the swing leg. ML CoP and CoM displacements during APA increased with increasing stance width. The activity of stance-leg TA was correlated with the degree of knee flexion. Swing-leg tensor fasciae latae (TFL) was also active during APA. Across subjects, when stance-leg tibialis activity was low, TFL activity was large and vice versa. The modulation of the ML CoP position during APA allowed the gravity-driven torque to place the CoM just lateral to the stance foot during step execution. Accordingly, the gravity-driven torque, the ML CoM velocity during step execution, and the step width at foot contact (FC) were lower in the Small and greater in the Large condition. Consequently, the position of the stepping foot at FC remained close to the sagittal plane in all three conditions. Conclusively, coordinated activation of hip abductors and ankle dorsiflexors during APA displaces the CoP towards the swing leg, and sets the contact position for the swing foot. PMID:27642280

Crystal truncation rods from miscut surfaces

DOE PAGES

Petach, Trevor A.; Mehta, Apurva; Toney, Michael F.; ...

2017-05-08

Crystal truncation rods are used to study surface and interface structure. Since real surfaces are always somewhat miscut from a low index plane, it is important to study the effect of miscuts on crystal truncation rods. We develop a model that describes the truncation rod scattering from miscut surfaces that have steps and terraces. We show that nonuniform terrace widths and jagged step edges are both forms of roughness that decrease the intensity of the rods. Nonuniform terrace widths also result in a broad peak that overlaps the rods. We use our model to characterize the terrace width distribution andmore » step edge jaggedness on three SrTiO 3 (001) samples, showing excellent agreement between the model and the data, confirmed by atomic force micrographs of the surface morphology. As a result, we expect our description of terrace roughness will apply to many surfaces, even those without obvious terracing.« less

A theoretical and experimental study of wood planer noise and its control

NASA Technical Reports Server (NTRS)

Stewart, J. S.

1972-01-01

A combined analytical and experimental study of wood planer noise is made and the results applied to the development of practical noise control techniques. The dominant mechanisms of sound generation are identified and an analysis is presented which accurately predicts the governing levels of noise emission. Planing operations in which the length of the board is much greater than the width are considered. The dominant source of planer noise is identified as the board being surfaced, which is set into vibration by the impact of cutterhead knives. This is determined from studies made both in the laboratory and in the field concerning the effect of board width on the resulting noise, which indicate a six decibel increase in noise level for each doubling of board width. The theoretical development of a model for board vibration defines the vibrational field set up in the board and serves as a guide for cutterhead redesign.

Microlensing of Extremely Magnified Stars near Caustics of Galaxy Clusters

NASA Astrophysics Data System (ADS)

Venumadhav, Tejaswi; Dai, Liang; Miralda-Escudé, Jordi

2017-11-01

Recent observations of lensed galaxies at cosmological distances have detected individual stars that are extremely magnified when crossing the caustics of lensing clusters. In idealized cluster lenses with smooth mass distributions, two images of a star of radius R approaching a caustic brighten as {t}-1/2 and reach a peak magnification ˜ {10}6{(10{R}⊙ /R)}1/2 before merging on the critical curve. We show that a mass fraction ({κ }\\star ≳ {10}-4.5) in microlenses inevitably disrupts the smooth caustic into a network of corrugated microcaustics and produces light curves with numerous peaks. Using analytical calculations and numerical simulations, we derive the characteristic width of the network, caustic-crossing frequencies, and peak magnifications. For the lens parameters of a recent detection and a population of intracluster stars with {κ }\\star ˜ 0.01, we find a source-plane width of ˜ 20 {pc} for the caustic network, which spans 0.2 {arcsec} on the image plane. A source star takes ˜ 2× {10}4 years to cross this width, with a total of ˜ 6× {10}4 crossings, each one lasting for ˜ 5 {hr} (R/10 {R}⊙ ) with typical peak magnifications of ˜ {10}4 {(R/10{R}⊙ )}-1/2. The exquisite sensitivity of caustic-crossing events to the granularity of the lens-mass distribution makes them ideal probes of dark matter components, such as compact halo objects and ultralight axion dark matter.

A Dual-Plane PIV Study of Turbulent Heat Transfer Flows

NASA Technical Reports Server (NTRS)

Wernet, Mark P.; Wroblewski, Adam C.; Locke, Randy J.

2016-01-01

Thin film cooling is a widely used technique in turbomachinery and rocket propulsion applications, where cool injection air protects a surface from hot combustion gases. The injected air typically has a different velocity and temperature from the free stream combustion flow, yielding a flow field with high turbulence and large temperature differences. These thin film cooling flows provide a good test case for evaluating computational model prediction capabilities. The goal of this work is to provide a database of flow field measurements for validating computational flow prediction models applied to turbulent heat transfer flows. In this work we describe the application of a Dual-Plane Particle Image Velocimetry (PIV) technique in a thin film cooling wind tunnel facility where the injection air stream velocity and temperatures are varied in order to provide benchmark turbulent heat transfer flow field measurements. The Dual-Plane PIV data collected include all three components of velocity and all three components of vorticity, spanning the width of the tunnel at multiple axial measurement planes.

On the Spectrum of the Plenoptic Function.

PubMed

Gilliam, Christopher; Dragotti, Pier-Luigi; Brookes, Mike

2014-02-01

The plenoptic function is a powerful tool to analyze the properties of multi-view image data sets. In particular, the understanding of the spectral properties of the plenoptic function is essential in many computer vision applications, including image-based rendering. In this paper, we derive for the first time an exact closed-form expression of the plenoptic spectrum of a slanted plane with finite width and use this expression as the elementary building block to derive the plenoptic spectrum of more sophisticated scenes. This is achieved by approximating the geometry of the scene with a set of slanted planes and evaluating the closed-form expression for each plane in the set. We then use this closed-form expression to revisit uniform plenoptic sampling. In this context, we derive a new Nyquist rate for the plenoptic sampling of a slanted plane and a new reconstruction filter. Through numerical simulations, on both real and synthetic scenes, we show that the new filter outperforms alternative existing filters.

Generation of uniformly oriented in-plane magnetization with near-unity purity in 4π microscopy.

PubMed

Wang, Sicong; Cao, Yaoyu; Li, Xiangping

2017-12-01

In this Letter, we numerically demonstrate the all-optical generation of uniformly oriented in-plane magnetization with near-unity purity (more than 99%) under a 4π microscopic configuration. This is achieved through focusing two counter-propagating vector beams consisting of coherently configured linear and radial components. Based on the Debye diffraction theory, constructive and destructive interferences of the focal field components can be tailored under the 4π configuration to generate high-purity uniformly polarized transverse and longitudinal electric-field components in the center of the focal region. Consequently, near-unity purity in-plane magnetization with a uniform orientation within the focal volume defined by the full width at half-maximum can be created through the inverse Faraday effect. In addition, it reveals that the purity of the in-plane magnetization is robust against the numerical aperture of the focal lens. This result expands the flexibility of magnetization manipulations through light and holds great potential in all-optical magnetic recording and spintronics.

Thick nonpolar m-plane and semipolar (10 1 ̅ 1 ̅) GaN on an ammonothermal seed by tri-halide vapor-phase epitaxy using GaCl3

NASA Astrophysics Data System (ADS)

Iso, Kenji; Matsuda, Karen; Takekawa, Nao; Hikida, Kazuhiro; Hayashida, Naoto; Murakami, Hisashi; Koukitu, Akinori

2017-03-01

GaN layers of thickness 0.5-1.3 mm were grown at 1280 °C at a growth rate of 95-275 μm/h by tri-halide vapor-phase epitaxy on nonpolar m-plane (10 1 ̅ 0) and semipolar (10 1 ̅ 1 ̅) ammonothermal GaN substrates. For nonpolar m-plane (10 1 ̅ 0) with a -5° off-angle, the full widths at half maximum (FWHMs) of X-ray rocking curves (XRCs) and the basal plane stacking fault (BSF) density increased from 50 to 178″ and from 4.8×101 to 1.0×103 cm-1, respectively, upon increasing the growth rate from 115 to 245 μm/h. On the other hand, the XRC-FWHM and the BSF density for semipolar (10 1 ̅ 1 ̅) grown at 275 μm/h were as small as 28″ and 8.3×101 cm-1, respectively.

A TEMPLATE-BASED FABRICATION TECHNIQUE FOR SPATIALLY-DESIGNED POLYMER MICRO/NANOFIBER COMPOSITES

PubMed Central

Naik, Nisarga; Caves, Jeff; Kumar, Vivek; Chaikof, Elliot; Allen, Mark G.

2013-01-01

This paper reports a template-based technique for the fabrication of polymer micro/nanofiber composites, exercising control over the fiber dimensions and alignment. Unlike conventional spinning-based methods of fiber production, the presented approach is based on micro-transfer molding. It is a parallel processing technique capable of producing fibers with control over both in-plane and out-of-plane geometries, in addition to packing density and layout of the fibers. Collagen has been used as a test polymer to demonstrate the concept. Hollow and solid collagen fibers with various spatial layouts have been fabricated. Produced fibers have widths ranging from 2 µm to 50 µm, and fiber thicknesses ranging from 300 nm to 3 µm. Also, three-dimensionality of the process has been demonstrated by producing in-plane serpentine fibers with designed arc lengths, out-of-plane wavy fibers, fibers with focalized particle encapsulation, and porous fibers with desired periodicity and pore sizes. PMID:24533428

Rectifying antenna and method of manufacture

NASA Technical Reports Server (NTRS)

Bhansali, Shekhar (Inventor); Buckle, Kenneth (Inventor); Goswami, D. Yogi (Inventor); Stefanakos, Elias (Inventor); Weller, Thomas (Inventor)

2006-01-01

In accordance with the present invention, an aperture rectenna is provided where the substrate is transparent and of sufficient mechanical strength to support the fabricated structure above it. An aperture antenna is deposited on the transparent substrate and a metal-insulator-metal (MIM) diode is constructed on top of the aperture antenna. There is an insulating layer between the aperture antenna metal and the metal ground plane optimized to maximize the collection of incident radiation. The top of the structure is capped with a metal ground plane layer, which also serves as the DC connection points for each rectenna element.

Comparison of Analysis, Simulation, and Measurement of Wire-to-Wire Crosstalk. Part 2

NASA Technical Reports Server (NTRS)

Bradley, Arthur T.; Yavoich, Brian James; Hodson, Shane M.; Godley, Franklin

2010-01-01

In this investigation, we compare crosstalk analysis, simulation, and measurement results for electrically short configurations. Methods include hand calculations, PSPICE simulations, Microstripes transient field solver, and empirical measurement. In total, four representative physical configurations are examined, including a single wire over a ground plane, a twisted pair over a ground plane, generator plus receptor wires inside a cylindrical conduit, and a single receptor wire inside a cylindrical conduit. Part 1 addresses the first two cases, and Part 2 addresses the final two. Agreement between the analysis methods and test data is shown to be very good.

Comparison of Analysis, Simulation, and Measurement of Wire-to-Wire Crosstalk. Part 1

NASA Technical Reports Server (NTRS)

Bradley, Arthur T.; Yavoich, Brian James; Hodson, Shame M.; Godley, Richard Franklin

2010-01-01

In this investigation, we compare crosstalk analysis, simulation, and measurement results for electrically short configurations. Methods include hand calculations, PSPICE simulations, Microstripes transient field solver, and empirical measurement. In total, four representative physical configurations are examined, including a single wire over a ground plane, a twisted pair over a ground plane, generator plus receptor wires inside a cylindrical conduit, and a single receptor wire inside a cylindrical conduit. Part 1 addresses the first two cases, and Part 2 addresses the final two. Agreement between the analysis, simulation, and test data is shown to be very good.

Improved memory word line configuration allows high storage density

NASA Technical Reports Server (NTRS)

1966-01-01

Plated wire memory word drive line allows high storage density, good plated wire transmission and a simplified memory plane configuration. A half-turn word drive line with a magnetic keeper is used. The ground plane provides the return path for both the word current and the plated wire transmission line.

3D two-photon lithographic microfabrication system

DOEpatents

Kim, Daekeun [Cambridge, MA; So, Peter T. C. [Boston, MA

2011-03-08

An imaging system is provided that includes a optical pulse generator for providing an optical pulse having a spectral bandwidth and includes monochromatic waves having different wavelengths. A dispersive element receives a second optical pulse associated with the optical pulse and disperses the second optical pulse at different angles on the surface of the dispersive element depending on wavelength. One or more focal elements receives the dispersed second optical pulse produced on the dispersive element. The one or more focal element recombine the dispersed second optical pulse at a focal plane on a specimen where the width of the optical pulse is restored at the focal plane.

Effects of toe-in and toe-in with wider step width on level walking knee biomechanics in varus, valgus, and neutral knee alignments.

PubMed

Bennett, Hunter J; Shen, Guangping; Cates, Harold E; Zhang, Songning

2017-12-01

Increased peak external knee adduction moments exist for individuals with knee osteoarthritis and varus knee alignments, compared to healthy and neutrally aligned counterparts. Walking with increased toe-in or increased step width have been individually utilized to successfully reduce 1st and 2nd peak knee adduction moments, respectfully, but have not previously been combined or tested among all alignment groups. The purpose of this study was to compare toe-in only and toe-in with wider step width gait modifications in individuals with neutral, valgus, and varus alignments. Thirty-eight healthy participants with confirmed varus, neutral, or valgus frontal-plane knee alignment through anteroposterior radiographs, performed level walking in normal, toe-in, and toe-in with wider step width gaits. A 3×3 (group×intervention) mixed model repeated measures ANOVA compared alignment groups and gait interventions (p<0.05). The 1st peak knee adduction moment was reduced in both toe-in and toe-in with wider step width compared to normal gait. The 2nd peak adduction moment was increased in toe-in compared to normal and toe-in with wider step width. The adduction impulse was also reduced in toe-in and toe-in with wider step width compared to normal gait. Peak knee flexion and external rotation moments were increased in toe-in and toe-in with wider step width compared to normal gait. Although the toe-in with wider step width gait seems to be a viable option to reduce peak adduction moments for varus alignments, sagittal, and transverse knee loadings should be monitored when implementing this gait modification strategy. Copyright © 2017 Elsevier B.V. All rights reserved.

The 24 GHz measurements of 2.2 lambda conical horn antennas illuminating a conducting sheet

NASA Technical Reports Server (NTRS)

Cross, A. E.; Marshall, R. E.; Hearn, C. P.; Neece, R. T.

1993-01-01

Monostatic reflection-coefficient magnitude, absolute value of Gamma, measurements occurring between a radiating horn and a metal reflecting plate are presented for a family of three 2.2 lambda diameter conical horn antennas. The three horns have different aperture phase deviations: 6 deg, 22.5 deg, and 125 deg. Measurements of the magnitude of absolute value of Gamma as a function of horn-plate separation (d) extend from an effective antenna aperture short (d = O) to beyond the far-field boundary (d = 2D(sup 2)/lambda, where D is the antenna diameter). Measurement data are presented with various physical environments for each of the horns. Measured scalar data are compared with theoretical data from two models, a numerical model for a circular waveguide aperture in a ground plane and a scalar diffraction theory model. This work was conducted in support of the development effort for a spaceborne multifrequency microwave reflectometer designed to accurately determine the distance from a space vehicle's surface to a reflecting plasma boundary. The metal reflecting plate was used to simulate the RF reflectivity of a critically dense plasma. The resulting configuration, a ground plane mounted aperture facing a reflecting plane in close proximity, produces a strong interaction between the ground plane and the reflecting plate, especially at integral half-wavelength separations. The transition coefficient is characterized by large amplitude variations.

The structure of a cometary type I tail - Ground-based and ICE observations of P/Giacobini-Zinner

NASA Technical Reports Server (NTRS)

Slavin, J. A.; Goldberg, B. A.; Smith, E. J.; Mccomas, D. J.; Bame, S. J.

1986-01-01

Comparison of ground-based and in situ observations of P/Giacobini-Zinner are used to investigate the morphology of a type I cometary tail. ICE magnetic field and plasma measurements show a well-defined cometary magnetotail composed of two magnetic lobes in pressure equilibrium with a central plasma sheet. A dependence of ion tail width on IMF direction is found which strongly suggests that the classical type I ion tails observed on the ground consist predominantly of emissions from the slab-shaped plasma sheet separating the magnetic lobes. The width of the G-Z magnetotail is determined to be 9.8 (+ or - 0.5) x 10 to the 3rd km with a quasi-circular cross section. The results of this study also indicate that some of the dynamical thinnings and thickenings observed in long type I tails may be caused by IMF variations changing the angle with which the plasma sheet is viewed at earth.

Design VHF Antennas for Space Borne Receivers for SmallSats

NASA Technical Reports Server (NTRS)

Deshpande, Manohar

2017-01-01

Space borne microwave remote sensors at VHF/UHF frequencies are important instruments to observe reflective properties of land surfaces through thick and heavy forestation on a global scale. One of the most cost effective ways of measuring land reflectivity at VHF/UHF frequencies is to use signals transmitted by existing communication satellites (operating at VHF/UHF band) as a signal of opportunity (SoOp) signal and passive receivers integrated with airborne/space borne platforms operating in the Low Earth Orbit (LEO). One of the critical components of the passive receiver is two antennas (one to receive only direct signal and other to receive only reflected signal) which need to have ideally high (>30dB) isolation. However, because of small size of host platforms and broad beam width of dipole antennas, achieving adequate isolation between two channels is a challenging problem and need to be solved for successful implementation of space borne SoOp technology for remote sensing. In this presentation a novel enabling VHF antenna technology for Cubesat platforms is presented to receive direct as well as reflected signal with needed isolation. The novel scheme also allows enhancing the gain of individual channels by factor of 2 without use of reflecting ground plane.

Possibility to Probe Negative Values of a Wigner Function in Scattering of a Coherent Superposition of Electronic Wave Packets by Atoms.

PubMed

Karlovets, Dmitry V; Serbo, Valeriy G

2017-10-27

Within a plane-wave approximation in scattering, an incoming wave packet's Wigner function stays positive everywhere, which obscures such purely quantum phenomena as nonlocality and entanglement. With the advent of the electron microscopes with subnanometer-sized beams, one can enter a genuinely quantum regime where the latter effects become only moderately attenuated. Here we show how to probe negative values of the Wigner function in scattering of a coherent superposition of two Gaussian packets with a nonvanishing impact parameter between them (a Schrödinger's cat state) by atomic targets. For hydrogen in the ground 1s state, a small parameter of the problem, a ratio a/σ_{⊥} of the Bohr radius a to the beam width σ_{⊥}, is no longer vanishing. We predict an azimuthal asymmetry of the scattered electrons, which is found to be up to 10%, and argue that it can be reliably detected. The production of beams with the not-everywhere-positive Wigner functions and the probing of such quantum effects can open new perspectives for noninvasive electron microscopy, quantum tomography, particle physics, and so forth.

Exploiting Inherent Robustness and Natural Dynamics in the Control of Bipedal Walking Robots

DTIC Science & Technology

2000-06-01

physical models of bipedal walking. The insight gained from these models is used in the development of three planar (motion only in the sagittal plane ...ground is implemented and tested in simulation. The dynamics of the sagittal plane are suffciently decoupled from the dynamics of the frontal and...transverse planes such that control of each can be treated separately. We achieve three-dimensional walking by adding lateral balance to the planar algorithms

The medial dye pool revisited: correlation between arthrography and MRI In closed reductions for DDH.

PubMed

Gans, Itai; Sankar, Wudbhav N

2014-12-01

Closed reduction (CR) and spica casting is performed using arthrography to assess the adequacy of reduction based in part on the width of medial dye pool (MDP); however, the amount of MDP that is acceptable and its correlation to the actual anatomic position of the femoral head within the acetabulum has been poorly delineated. The purpose of this study was to determine this correlation and to explore the potential limits of acceptable MDP measurements. We retrospectively reviewed a consecutive series of patients with DDH treated at our institution by CR and immediate postoperative magnetic resonance imaging (MRI) and found 20 patients (23 hips) meeting inclusion criteria. We measured the MDP and femoral head area on the best reduced arthrographic image, the immediate postoperative mid-coronal MRI, and on 3 planes (neutral, 30-degree anterior, and 30-degree posterior) of the mid-axial MRI and compared MDP values from both imaging modalities using the Pearson correlation coefficient (R). To provide useful data for establishing intraoperative thresholds, MDP was also expressed as a percentage of femoral head width to control for fluoroscopic magnification. Twenty-two of the 23 hips were reduced on postoperative MRI; the one persistently dislocated hip was excluded from our analysis. The Pearson correlation coefficient was R = 0.73 comparing arthrography and coronal MRI, indicating excellent correlation. Correlation was even stronger between arthrography and axial MRI (neutral R = 0.73; 30-degree anterior, R = 0.81; 30-degree posterior, R = 0.81). The mean fluoroscopic MDP in the successful, fully concentric, CRs was 4.2% of the femoral head width (range, 0.6% to 15.8%). There is very strong correlation between MDP measurements on arthrography and immediate postoperative MRI in both the axial and coronal planes. On the basis of our data, an arthrographic MDP between 0.6% and 15.8% of the femoral head width always resulted in an excellent reduction, suggesting that an MDP of ≤ 16% of femoral head width may be a useful intraoperative criterion for determining the adequacy of CR. Level I Diagnostic Study.

The Relationship Between the Expansion Speed and Radial Speed of CMEs Confirmed Using Quadrature Observations of the 2011 February 15 CME

NASA Astrophysics Data System (ADS)

Gopalswamy, N.; Makela, P.; Yashiro, S.; Davila, J. M.

2012-08-01

It is difficult to measure the true speed of Earth-directed CMEs from a coronagraph along the Sun-Earth line because of the occulting disk. However, the expansion speed (the speed with which the CME appears to spread in the sky plane) can be measured by such coronagraph. In order to convert the expansion speed to radial speed (which is important for space weather applications) one can use empirical relationship between the two that assumes an average width for all CMEs. If we have the width information from quadrature observations, we can confirm the relationship between expansion and radial speeds derived by Gopalswamy et al. (2009a). The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth by 87oand STEREO-B 94obehind Earth) on 2011 February 15, when a fast Earth-directed CME occurred. The CME was observed as a halo by the Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The sky-plane speed was measured by SOHO/LASCO as the expansion speed, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp) and radial speed (Vrad) derived previously from geometrical considerations (Gopalswamy et al. 2009a): Vrad=1/2 (1 + cot w)Vexp, where w is the half width of the CME. STEREO-B images of the CME, we found that CME had a full width of 7 6o, so w=3 8o. This gives the relation as Vrad=1.1 4 Vexp. From LASCO observations, we measured Vexp=897 km/s, so we get the radial speed as 10 2 3 km/s. Direct measurement of radial speed yields 945 km/s (STEREO-A) and 105 8 km/s (STEREO-B). These numbers are different only by 7.6 % and 3.4 % (for STEREO-A and STEREO-B, respectively) from the computed value.

Relationship Between the Expansion Speed and Radial Speed of CMEs Confirmed Using Quadrature Observations from SOHO and STEREO

NASA Technical Reports Server (NTRS)

Gopalswamy, Nat; Makela, Pertti; Yashiro, Seiji

2011-01-01

It is difficult to measure the true speed of Earth-directed CMEs from a coronagraph along the Sun-Earth line because of the occulting disk. However, the expansion speed (the speed with which the CME appears to spread in the sky plane) can be measured by such coronagraph. In order to convert the expansion speed to radial speed (which is important for space weather applications) one can use empirical relationship between the two that assumes an average width for all CMEs. If we have the width information from quadrature observations, we can confirm the relationship between expansion and radial speeds derived by Gopalswamy et al. (2009, CEAB, 33, 115,2009). The STEREO spacecraft were in quadrature with SOHO (STEREO-A ahead of Earth by 87 and STEREO-B 94 behind Earth) on 2011 February 15, when a fast Earth-directed CME occurred. The CME was observed as a halo by the Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The sky-plane speed was measured by SOHO/LASCO as the expansion speed, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp ) and radial speed (Vrad ) derived previously from geometrical considerations (Gopalswamy et al. 2009): Vrad = 1/2 (1 + cot w) Vexp, where w is the half width of the CME. STEREO-B images of the CME, we found that CME had a full width of 75 degrees, so w = 37.5 degrees. This gives the relation as Vrad = 1.15 Vexp. From LASCO observations, we measured Vexp = 897 km/s, so we get the radial speed as 1033 km/s. Direct measurement of radial speed from STEREO gives 945 km/s (STEREO-A) and 1057 km/s (STEREO-B). These numbers are different only by 2.3% and 8.5% (for STEREO-A and STEREO-B, respectively) from the computed value.

Lower extremity energy absorption and biomechanics during landing, part II: frontal-plane energy analyses and interplanar relationships.

PubMed

Norcross, Marc F; Lewek, Michael D; Padua, Darin A; Shultz, Sandra J; Weinhold, Paul S; Blackburn, J Troy

2013-01-01

Greater sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing is consistent with sagittal-plane biomechanics that likely increase anterior cruciate ligament (ACL) loading, but it does not appear to influence frontal-plane biomechanics. We do not know whether frontal-plane INI EA is related to high-risk frontal-plane biomechanics. To compare biomechanics among INI EA groups, determine if women are represented more in the high group, and evaluate interplanar INI EA relationships. Descriptive laboratory study. Research laboratory. Participants included 82 (41 men, 41 women; age = 21.0 ± 2.4 years, height = 1.74 ± 0.10 m, mass = 70.3 ± 16.1 kg) healthy, physically active volunteers. We assessed landing biomechanics with an electromagnetic motion-capture system and force plate. We calculated frontal- and sagittal-plane total, hip, knee, and ankle INI EA. Total frontal-plane INI EA was used to create high, moderate, and low tertiles. Frontal-plane knee and hip kinematics, peak vertical and posterior ground reaction forces, and peak internal knee-varus moment (pKVM) were identified and compared across groups using 1-way analyses of variance. We used a χ (2) analysis to evaluate male and female allocation to INI EA groups. We used simple, bivariate Pearson product moment correlations to assess interplanar INI EA relationships. The high-INI EA group exhibited greater knee valgus at ground contact, hip adduction at pKVM, and peak hip adduction than the low-INI EA group (P < .05) and greater peak knee valgus, pKVM, and knee valgus at pKVM than the moderate- (P < .05) and low- (P < .05) INI EA groups. Women were more likely than men to be in the high-INI EA group (χ(2) = 4.909, P = .03). Sagittal-plane knee and frontal-plane hip INI EA (r = 0.301, P = .006) and sagittal-plane and frontal-plane ankle INI EA were associated (r = 0.224, P = .04). No other interplanar INI EA relationships were found (P > .05). Greater frontal-plane INI EA was associated with less favorable frontal-plane biomechanics that likely result in greater ACL loading. Women were more likely than men to use greater frontal-plane INI EA. The magnitudes of sagittal- and frontal-plane INI EA were largely independent.

Near ground measure and theoretical model of plane wave covariance of intensity in anisotropic turbulence.

PubMed

Beason, Melissa; Smith, Christopher; Coffaro, Joseph; Belichki, Sara; Spychalsky, Jonathon; Titus, Franklin; Crabbs, Robert; Andrews, Larry; Phillips, Ronald

2018-06-01

Experimental measurements were recently made which displayed characteristics of plane wave propagation through anisotropic optical turbulence. A near-plane wave beam was propagated a distance of 1 and 2 km at a height of 2 m above the concrete runway at the Shuttle Landing Facility, Kennedy Space Center, Florida, during January and February of 2017. The spatial-temporal fluctuations of the beam were recorded, and the covariance of intensity was calculated. These data sets were compared to a theoretical calculation of covariance of intensity for a plane wave.

Sensor lighting considerations for earth observatory satellite missions

NASA Technical Reports Server (NTRS)

Cooley, J. L.

1972-01-01

Facets of sensor lighting conditions for Earth observatory satellite missions are considered. Assuming onboard sensors of a given width viewing perpendicular to the subsatellite ground track along sun-synchronous orbits with various nodes, the ground trace of the ends of the sensor coverage were found, as well as the variation in solar illumination on the ground across the line covered by the sensor during the day for any point along the orbit. The changes with season and variation during the year were also found.

EEsoF MICAD and ACADEMY macro files for coplanar waveguide and finite ground plan coplanar waveguide

NASA Technical Reports Server (NTRS)

Ponchak, George E.

1995-01-01

A collection of macro files is presented which when appended to either the EEsoF MICAD.ELE or EEsoF ACADEMY.ELE file permits the layout of coplanar waveguide and finite ground plane coplanar waveguide circuits.

Gaze behavior and the perception of egocentric distance

PubMed Central

Gajewski, Daniel A.; Wallin, Courtney P.; Philbeck, John W.

2014-01-01

The ground plane is thought to be an important reference for localizing objects, particularly when angular declination is informative, as it is for objects seen resting at floor level. A potential role for eye movements has been implicated by the idea that information about the nearby ground is required to localize objects more distant, and by the fact that the time course for the extraction of distance extends beyond the duration of a typical eye fixation. To test this potential role, eye movements were monitored when participants previewed targets. Distance estimates were provided by walking without vision to the remembered target location (blind walking) or by verbal report. We found that a strategy of holding the gaze steady on the object was as frequent as one where the region between the observer and object was fixated. There was no performance advantage associated with making eye movements in an observational study (Experiment 1) or when an eye-movement strategy was manipulated experimentally (Experiment 2). Observers were extracting useful information covertly, however. In Experiments 3 through 5, obscuring the nearby ground plane had a modest impact on performance; obscuring the walls and ceiling was more detrimental. The results suggest that these alternate surfaces provide useful information when judging the distance to objects within indoor environments. Critically, they constrain the role for the nearby ground plane in theories of egocentric distance perception. PMID:24453346

PIC simulations of the trapped electron filamentation instability in finite-width electron plasma waves

NASA Astrophysics Data System (ADS)

Winjum, B. J.; Banks, J. W.; Berger, R. L.; Cohen, B. I.; Chapman, T.; Hittinger, J. A. F.; Rozmus, W.; Strozzi, D. J.; Brunner, S.

2012-10-01

We present results on the kinetic filamentation of finite-width nonlinear electron plasma waves (EPW). Using 2D simulations with the PIC code BEPS, we excite a traveling EPW with a Gaussian transverse profile and a wavenumber k0λDe= 1/3. The transverse wavenumber spectrum broadens during transverse EPW localization for small width (but sufficiently large amplitude) waves, while the spectrum narrows to a dominant k as the initial EPW width increases to the plane-wave limit. For large EPW widths, filaments can grow and destroy the wave coherence before transverse localization destroys the wave; the filaments in turn evolve individually as self-focusing EPWs. Additionally, a transverse electric field develops that affects trapped electrons, and a beam-like distribution of untrapped electrons develops between filaments and on the sides of a localizing EPW. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12-ERD-061. Supported also under Grants DE-FG52-09NA29552 and NSF-Phy-0904039. Simulations were performed on UCLA's Hoffman2 and NERSC's Hopper.

Particle-in-Cell Simulation of Collisionless Driven Reconnection with Open Boundaries

NASA Technical Reports Server (NTRS)

Kimas, Alex; Hesse, Michael; Zenitani, Seiji; Kuznetsova, Maria

2010-01-01

First results are discussed from an ongoing study of driven collisionless reconnection using a 2 1/2-dimensional electromagnetic particle-in-cell simulation model with open inflow and outflow boundaries. An extended electron diffusion region (EEDR) is defined as that region surrounding a reconnecting neutral line in which the out-of-plane nonideal electric field is positive. It is shown that the boundaries of this region in the directions of the outflow jets are at the positions where the electrons make the transition from unfrozen meandering motion in the current sheet to outward drifting with the magnetic field in the outflow jets; a turning length scale is defined to mark these positions, The initial width of the EEDR in the inflow directions is comparable to the electron bounce width. Later. as shoulders develop to form a two-scale structure. thc EEDR width expands to the ion bounce width scale. The inner portion of the EEDR or the electron diffusion region proper remains at the electron bounce width. Two methods are introduced for predicting the reconnection electric field using the dimensions of the EEDR. These results are interpreted as further evidence that the EEDR is the region that is relevant to understanding the electron role in the neutral line vicinity.

The acoustic field of a point source in a uniform boundary layer over an impedance plane

NASA Technical Reports Server (NTRS)

Zorumski, W. E.; Willshire, W. L., Jr.

1986-01-01

The acoustic field of a point source in a boundary layer above an impedance plane is investigated anatytically using Obukhov quasi-potential functions, extending the normal-mode theory of Chunchuzov (1984) to account for the effects of finite ground-plane impedance and source height. The solution is found to be asymptotic to the surface-wave term studies by Wenzel (1974) in the limit of vanishing wind speed, suggesting that normal-mode theory can be used to model the effects of an atmospheric boundary layer on infrasonic sound radiation. Model predictions are derived for noise-generation data obtained by Willshire (1985) at the Medicine Bow wind-turbine facility. Long-range downwind propagation is found to behave as a cylindrical wave, with attention proportional to the wind speed, the boundary-layer displacement thickness, the real part of the ground admittance, and the square of the frequency.

Acoustic-to-Seismic Coupling Over Porous Ground Surfaces.

DTIC Science & Technology

1984-01-01

of sound into the ground is predicted for both spherical and plane acoustic waves incident upon two models of the ground viz i) a rigid porous solid...and soils of above-ground acoustic disturbances. Furthermore it is found possible to predict the results of model measurements using continuous and...saddle point 2.4 The geometrical wave 2.5 The lateral wave 2.6 Special cases 3. POINT TO POINT PROPAGATION MEASUREMENTS USING ACOUSTIC MODELLING " 3.0

Design and control of the MINDWALKER exoskeleton.

PubMed

Wang, Shiqian; Wang, Letian; Meijneke, Cory; van Asseldonk, Edwin; Hoellinger, Thomas; Cheron, Guy; Ivanenko, Yuri; La Scaleia, Valentina; Sylos-Labini, Francesca; Molinari, Marco; Tamburella, Federica; Pisotta, Iolanda; Thorsteinsson, Freygardur; Ilzkovitz, Michel; Gancet, Jeremi; Nevatia, Yashodhan; Hauffe, Ralf; Zanow, Frank; van der Kooij, Herman

2015-03-01

Powered exoskeletons can empower paraplegics to stand and walk. Actively controlled hip ab/adduction (HAA) is needed for weight shift and for lateral foot placement to support dynamic balance control and to counteract disturbances in the frontal plane. Here, we describe the design, control, and preliminary evaluation of a novel exoskeleton, MINDWALKER. Besides powered hip flexion/extension and knee flexion/extension, it also has powered HAA. Each of the powered joints has a series elastic actuator, which can deliver 100 Nm torque and 1 kW power. A finite-state machine based controller provides gait assistance in both the sagittal and frontal planes. State transitions, such as stepping, can be triggered by the displacement of the Center of Mass (CoM). A novel step-width adaptation algorithm was proposed to stabilize lateral balance. We tested this exoskeleton on both healthy subjects and paraplegics. Experimental results showed that all users could successfully trigger steps by CoM displacement. The step-width adaptation algorithm could actively counteract disturbances, such as pushes. With the current implementations, stable walking without crutches has been achieved for healthy subjects but not yet for SCI paraplegics. More research and development is needed to improve the gait stability.

Eye structure and amphibious foraging in albatrosses

PubMed Central

Martin, G. R.

1998-01-01

Anterior eye structure and retinal visual fields were determined in grey-headed and black-browed albatrosses, Diomedea melanophris and D. chrysostoma (Procellariiformes, Diomedeidae), using keratometry and an ophthalmoscopic reflex technique. Results for the two species were very similar and indicate that the eyes are of an amphibious optical design suggesting that albatross vision is well suited to the visual pursuit of active prey both on and below the ocean surface. The corneas are relatively flat (radius ca. 14.5 mm) and hence of low absolute refractive power (ca. 23 dioptres). In air the binocular fields are relatively long (vertical extent ca. 70 degrees) and narrow (maximum width in the plane of the optic axes 26–32 degrees), a topography found in a range of bird species that employ visual guidance of bill position when foraging. The cyclopean fields measure approximately 270 degrees in the horizontal plane, but there is a 60 degrees blind sector above the head owing to the positioning of the eyes below the protruding supraorbital ridges. Upon immersion the monocular fields decrease in width such that the binocular fields are abolished. Anterior eye structure, and visual field topography in both air and water, show marked similarity with those of the Humboldt penguin.

Broadband rectangular TEn0 mode exciter with H-plane power dividers for 100 GHz confocal gyro-devices.

PubMed

Yao, Yelei; Wang, Jianxun; Li, Hao; Liu, Guo; Luo, Yong

2017-07-01

A generic approach to excite TE n0 (n ≥ 1) modes in a rectangular waveguide for confocal gyro-devices is proposed. The exciter consists of a 3 dB H-plane power divider (n ≥ 3) and a mode-converting section. The injection power is split into two in-phase signals with equal amplitudes which simultaneously excite the secondary waveguide via two sets of multiple slots. Both the position and width of the slot are symmetrically distributed with respect to the center line for each set of slots. The slot width complies with a geometry sequence, with adjacent slots being spaced a quarter wavelength apart to cancel the backward wave out. A TE 40 mode exciter at 100 GHz is numerically simulated and optimized, achieving a 1 dB and a 3 dB transmission bandwidth of 18.2 and 21 GHz, respectively. The prototype is fabricated and measured. The cold test is carried out utilizing two identical back-to-back connected mode exciters, and the measured performances are in good agreement with the numerical simulation results when taking into account the wall loss and assembly tolerance.

Three Dimensional Parametric Analyses of Stress Concentration Factor and Its Mitigation in Isotropic and Orthotropic Plate with Central Circular Hole Under Axial In-Plane Loading

NASA Astrophysics Data System (ADS)

Nagpal, Shubhrata; Jain, Nitin Kumar; Sanyal, Shubhashis

2016-01-01

The problem of finding the stress concentration factor of a loaded rectangular plate has offered considerably analytical difficulty. The present work focused on understanding of behavior of isotropic and orthotropic plate subjected to static in-plane loading using finite element method. The complete plate model configuration has been analyzed using finite element method based software ANSYS. In the present work two parameters: thickness to width of plate (T/A) and diameter of hole to width of plate (D/A) have been varied for analysis of stress concentration factor (SCF) and its mitigation. Plates of five different materials have been considered for complete analysis to find out the sensitivity of stress concentration factor. The D/A ratio varied from 0.1 to 0.7 for analysis of SCF and varied from 0.1 to 0.5 for analyzing the mitigation of SCF. 0.01, 0.05 and 0.1 are considered as T/A ratio for all the cases. The results are presented in graphical form and discussed. The mitigation in SCF reported is very encouraging. The SCF is more sensitive to D/A ratio as compared to T/A.

Unbiased multi-fidelity estimate of failure probability of a free plane jet

NASA Astrophysics Data System (ADS)

Marques, Alexandre; Kramer, Boris; Willcox, Karen; Peherstorfer, Benjamin

2017-11-01

Estimating failure probability related to fluid flows is a challenge because it requires a large number of evaluations of expensive models. We address this challenge by leveraging multiple low fidelity models of the flow dynamics to create an optimal unbiased estimator. In particular, we investigate the effects of uncertain inlet conditions in the width of a free plane jet. We classify a condition as failure when the corresponding jet width is below a small threshold, such that failure is a rare event (failure probability is smaller than 0.001). We estimate failure probability by combining the frameworks of multi-fidelity importance sampling and optimal fusion of estimators. Multi-fidelity importance sampling uses a low fidelity model to explore the parameter space and create a biasing distribution. An unbiased estimate is then computed with a relatively small number of evaluations of the high fidelity model. In the presence of multiple low fidelity models, this framework offers multiple competing estimators. Optimal fusion combines all competing estimators into a single estimator with minimal variance. We show that this combined framework can significantly reduce the cost of estimating failure probabilities, and thus can have a large impact in fluid flow applications. This work was funded by DARPA.

Analysis of a turbulent boundary layer over a moving ground plane

NASA Technical Reports Server (NTRS)

Roper, A. T.; Gentry, G. L., Jr.

1972-01-01

Four methods of predicting the integral and friction parameters for a turbulent boundary layer over a moving ground plane were evaluated by using test information obtained in 76.2- by 50.8-centimeter tunnel. The tunnel was operated in the open sidewall configuration. These methods are (1) relative integral parameter method, (2) modified power law method, (3) relative power law method, and (4) modified law of the wall method. The modified law of the wall method predicts a more rapid decrease in skin friction with an increase in the ratio of belt velocity to free steam velocity than do methods (1) and (3).

Fan-fold shielded electrical leads

DOEpatents

Rohatgi, Rajeev R.; Cowan, Thomas E.

1996-01-01

Fan-folded electrical leads made from copper cladded Kapton, for example, with the copper cladding on one side serving as a ground plane and the copper cladding on the other side being etched to form the leads. The Kapton is fan folded with the leads located at the bottom of the fan-folds. Electrical connections are made by partially opening the folds of the fan and soldering, for example, the connections directly to the ground plane and/or the lead. The fan folded arrangement produces a number of advantages, such as electrically shielding the leads from the environment, is totally non-magnetic, and has a very low thermal conductivity, while being easy to fabricate.

Polarization-independent dual-band terahertz metamaterial absorbers based on gold/parylene-C/silicide structure.

PubMed

Wen, Yongzheng; Ma, Wei; Bailey, Joe; Matmon, Guy; Yu, Xiaomei; Aeppli, Gabriel

2013-07-01

We design, fabricate, and characterize dual-band terahertz (THz) metamaterial absorbers with high absorption based on structures consisting of a cobalt silicide (Co-Si) ground plane, a parylene-C dielectric spacer, and a metal top layer. By combining two periodic metal resonators that couple separately within a single unit cell, a polarization-independent absorber with two distinct absorption peaks was obtained. By varying the thickness of the dielectric layer, we obtain absorptivity of 0.76 at 0.76 THz and 0.97 at 2.30 THz, which indicates the Co-Si ground plane absorbers present good performance.

Stereo depth and the control of locomotive heading

NASA Astrophysics Data System (ADS)

Rushton, Simon K.; Harris, Julie M.

1998-04-01

Does the addition of stereoscopic depth aid steering--the perceptual control of locomotor heading--around an environment? This is a critical question when designing a tele-operation or Virtual Environment system, with implications for computational resources and visual comfort. We examined the role of stereoscopic depth in the perceptual control of heading by employing an active steering task. Three conditions were tested: stereoscopic depth; incorrect stereoscopic depth and no stereoscopic depth. Results suggest that stereoscopic depth does not improve performance in a visual control task. A further set of experiments examined the importance of a ground plane. As a ground plane is a common feature of all natural environments and provides a pictorial depth cue, it has been suggested that the visual system may be especially attuned to exploit its presence. Thus it would be predicted that a ground plane would aid judgments of locomotor heading. Results suggest that the presence of rich motion information in the lower visual field produces significant performance advantages and that provision of such information may prove a better target for system resources than stereoscopic depth. These findings have practical consequences for a system designer and also challenge previous theoretical and psychophysical perceptual research.

Ground beetle communities in a mountain river subjected to restoration: The Raba River, Polish Carpathians.

PubMed

Bednarska, Agnieszka J; Wyżga, Bartłomiej; Mikuś, Paweł; Kędzior, Renata

2018-01-01

Effects of passive restoration of mountain rivers on the organisms inhabiting exposed riverine sediments are considerably less understood than those concerning aquatic biota. Thus, the effects of a recovery of the Raba River after abandonment of maintenance of its channelization scheme on ground beetle (Coleoptera: Carabidae) communities were investigated by comparing 6 unmanaged cross-sections and 6 cross-sections from adjacent channelized reaches. In each cross-section, ground beetles were collected from 12 sampling sites in spring, summer, and autumn, and 8 habitat parameters characterizing the cross-sections and sampling sites were determined. Within a few years after abandonment of the Raba River channelization scheme, the width of this gravel-bed river increased up to three times and its multi-thread pattern became re-established. Consequently, unmanaged river cross-sections had significantly larger channel width and more low-flow channels and eroding cutbanks than channelized cross-sections. Moreover, sampling sites in the unmanaged cross-sections were typified by significantly steeper average surface slope and larger average distance from low-flow channels than the sites in channelized cross-sections. In total, 3992 individuals from 78 taxa were collected during the study. The ground beetle assemblages were significantly more abundant and richer in species in the unmanaged than in the channelized cross-sections but no significant differences in carabid diversity indices between the two cross-section types were recorded. Redundancy Analysis indicated active river zone width as the only variable explaining differences in abundance and species richness among the cross-sections. Multiple regression analysis indicated species diversity to predominantly depend on the degree of plant cover and substrate grain size. The study showed that increased availability of exposed sediments in the widened river reaches allowed ground beetles to increase their abundance and species richness within a few years after the onset of river restoration, but more time may be needed for development of more diverse carabid communities. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparing photonic band structure calculation methods for diamond and pyrochlore crystals.

PubMed

Vermolen, E C M; Thijssen, J H J; Moroz, A; Megens, M; van Blaaderen, A

2009-04-27

The photonic band diagrams of close-packed colloidal diamond and pyrochlore structures, have been studied using Korringa-Kohn-Rostoker (KKR) and plane-wave calculations. In addition, the occurrence of a band gap has been investigated for the binary Laves structures and their constituent large- and small-sphere substructures. It was recently shown that these Laves structures give the possibility to fabricate the diamond and pyrochlore structures by self-organization. The comparison of the two calculation methods opens the possibility to study the validity and the convergence of the results, which have been an issue for diamond-related structures in the past. The KKR calculations systematically give a lower value for the gap width than the plane-wave calculations. This difference can partly be ascribed to a convergence issue in the plane-wave code when a contact point of two spheres coincides with the grid.

One-dimensional analysis of plane and radial thin film flows including solid-body rotation

NASA Technical Reports Server (NTRS)

Thomas, S.; Hankey, W.; Faghri, A.; Swanson, T.

1989-01-01

The flow of a thin liquid film with a free surface along a horizontal plate which emanates from a pressurized vessel is examined by integrating the equations of motion across the thin liquid layer and discretizing the integrated equations using finite difference techniques. The effects of 0-g and solid-body rotation will be discussed. The two cases of interest are plane flow and radial flow. In plane flow, the liquid is considered to be flowing along a channel with no change in the width of the channel, whereas in radial flow the liquid spreads out radially over a disk, so that the area changes along the radius. It is desired to determine the height of the liquid film at any location along the plate of disk, so that the heat transfer from the plate or disk can be found. The possibility that the flow could encounter a hydraulic jump is accounted for.

High Sensitivity Long-Wavelength Infrared QWIP Focal Plane Array Based Instrument for Remote Sensing of Icy Satellites

NASA Technical Reports Server (NTRS)

Gunapala, S.; Bandara, S.; Ivanov, A.

2003-01-01

GaAs based Quantum Well Infrared Photodetector (QWIP) technology has shown remarkable success in advancing low cost, highly uniform, high-operability, large format multi-color focal plane arrays. QWIPs afford greater flexibility than the usual extrinsically doped semiconductor IR detectors. The wavelength of the peak response and cutoff can be continuously tailored over a range wide enough to enable light detection at any wavelength range between 6 and 20 micron. The spectral band-width of these detectors can be tuned from narrow (Deltalambda/lambda is approximately 10%) to wide (Deltalambda/lambda is approximately 40%) allowing various applications. Furthermore, QWIPs offer low cost per pixel and highly uniform large format focal plane arrays due to mature GaAs/AlGaAs growth and processing technologies. The other advantages of GaAs/AlGaAs based QWIPS are higher yield, lower l/f noise and radiation hardness (1.5 Mrad). In this presentation, we will discuss our recent demonstrations of 640x512 pixel narrow-band, broad-band, multi-band focal plane arrays, and the current status of the development of 1024x1024 pixel long-wavelength infrared QWIP focal plane arrays.

Controls on bedrock bedform development at the base of the Uummannaq Ice Stream System, West Greenland

NASA Astrophysics Data System (ADS)

Lane, Tim; Roberts, David; Rea, Brice; Cofaigh, Colm Ó.

2014-05-01

This research investigates the glacial and non-glacial controls on glacially eroded bedrock bedforms beneath the topographically confined upstream fjord region of the Uummannaq Ice Stream (UIS), West Greenland. The UIS was a cross-shelf ice stream system that operated during the Last Glacial Maximum (LGM), formed of 10 coalescent outlet glaciers. Reconstructions suggest that palaeo-glaciological conditions were similar for all sites in the study, characterised by thick, fast flowing ice moving over a rigid bedrock bed. Areally scoured terrain were mapped using remotely sensed imagery to assess regional-scale patterns of glacial erosion and to select suitable field locations. In the field, bedform measurements were taken from four discrete areas within two neighbouring fjords in the northern Uummannaq region (Rink-Karrat and Ingia). Classic bedrock bedforms indicative of glacially eroded terrain were mapped, including p-forms, roche moutonnées, and whalebacks. Bedform long axes and plucked face orientations display close correlation with palaeo-ice flow directions inferred from striae measurements. Across all sites, elongation ratios (length to width) varied by an order of magnitude between 0.8:1 and 8.4:1. Bedform properties (length, height, width, and long axis orientation) from the four sample areas form individual morphometrically distinct populations. However, bedform populations display high inter-area variability despite their close proximity, and hypothesised similarity in palaeo-glaciological conditions. The relationship of bedforms to palaeo-glaciological conditions in this study is not simple, having been complicated by bedrock properties. Geological structures including: joint frequency; joint dip; joint orientation; bedding plane thickness; and bedding plane dip have provided lines of geological weakness along which glacial erosion has been able to focus, controlling bedform length and width. Lateral plucking, a mechanism previously described for the development of megagroove features, is invoked here for the formation of whaleback-type bedforms in Ingia Fjord. Bedding plane thickness and bedding plane dip relative to palaeo-ice flow direction and is shown to a key control on bedform morphology and ELR. Consequently, a knowledge of bedding plane dip relative to palaeo-ice flow can allow predictions to be made about likely bedform shape, relative length, amplitude, and wavelength. These predictions have important ramifications for understanding subglacial bed roughness, cavity formation, and likely ice-bed erosion processes. These observations demonstrate the direct link between bedrock bedform properties and underlying geological structure. This supports evidence which suggests that the use of bedrock bedform characteristics to directly infer palaeo-glaciological conditions must be approached with caution. In order to robustly understand bedform morphology, a full appreciation of local geological structure is necessary.

EFFECTS OF X-RAY BEAM ANGLE AND GEOMETRIC DISTORTION ON WIDTH OF EQUINE THORACOLUMBAR INTERSPINOUS SPACES USING RADIOGRAPHY AND COMPUTED TOMOGRAPHY-A CADAVERIC STUDY.

PubMed

Djernaes, Julie D; Nielsen, Jon V; Berg, Lise C

2017-03-01

The widths of spaces between the thoracolumbar processi spinosi (interspinous spaces) are frequently assessed using radiography in sports horses; however effects of varying X-ray beam angles and geometric distortion have not been previously described. The aim of this prospective, observational study was to determine whether X-ray beam angle has an effect on apparent widths of interspinous spaces. Thoracolumbar spine specimens were collected from six equine cadavers and left-right lateral radiographs and sagittal and dorsal reconstructed computed tomographic (CT) images were acquired. Sequential radiographs were acquired with each interspinous space in focus. Measurements were performed for each interspinous space in the focus position and up to eight angled positions as the interspinous space moved away from focus (±). Focus position measurements were compared to matching sagittal CT measurements. Effect of geometric distortion was evaluated by comparing the interspinous space in radiographs with sagittal and dorsal reconstructed CT images. A total of 49 interspinous spaces were sampled, yielding 274 measurements. X-ray beam angle significantly affected measured width of interspinous spaces in position +3 (P = 0.038). Changes in width did not follow a consistent pattern. Interspinous space widths in focus position were significantly smaller in radiographs compared to matching reconstructed CT images for backs diagnosed with kissing spine syndrome (P < 0.001). Geometric distortion markedly affected appearance of interspinous space width between planes. In conclusion, X-ray beam angle and geometric distortion influence radiographically measured widths of interspinous spaces in the equine thoracolumbar spine, and this should be taken into consideration when evaluating sport horses. © 2016 American College of Veterinary Radiology.

Skeletal and dental changes in the sagittal, vertical, and transverse dimensions after rapid palatal expansion.

PubMed

Chung, Chun-Hsi; Font, Blanca

2004-11-01

The purpose of this study was to examine the maxillary and mandibular responses to rapid palatal expansion (RPE) in all 3 dimensions. Twenty children (average age, 11.7 years) who required RPE treatment were included in this study. Pre- (T1) and post-RPE (T2) lateral and posteroanterior (PA) cephalograms and study models were taken for all patients. For each patient, lateral and PA cephalograms at T1 and T2 were traced, and the sagittal, vertical, and transverse measurements were made. In addition, on the pre- and postexpansion models, the widths between the first premolars, the first molars, and the two acrylic halves of the Haas-type expander were measured. Results showed that from T1 to T2, the mean SNA increased 0.35 degrees (P < .05) and ANB increased 1.00 degrees (P < .05). Both the ANS and PNS moved downward (1.30 mm and 1.43 mm, respectively, P < .05), and the mandibular plane angle (MP-SN) increased 1.72 degrees (P < .05). The maxillary and mandibular incisors did not change significantly after RPE. After RPE, the mean increase of maxillary interpremolar width, maxillary intermolar width, maxillary width (J-J), nasal width, and interorbital width were found to be 110.7%, 104.5%, 30.1%, 23.1%, and 3.3% of the screw expansion, respectively. After RPE treatment in children, the maxilla displaced slightly forward and downward (P < .05); the mandible rotated downward and backward, and the anterior facial height increased significantly (P < .05); and the widths of the maxilla and nasal cavity increased significantly (P < .05).

Hip rotation angle is associated with frontal plane knee joint mechanics during running.

PubMed

Sakaguchi, Masanori; Shimizu, Norifumi; Yanai, Toshimasa; Stefanyshyn, Darren J; Kawakami, Yasuo

2015-02-01

Inability to control lower extremity segments in the frontal and transverse planes resulting in large knee abduction angle and increased internal knee abduction impulse has been associated with patellofemoral pain (PFP). However, the influence of hip rotation angles on frontal plane knee joint kinematics and kinetics remains unclear. The purpose of this study was to explore how hip rotation angles are related to frontal plane knee joint kinematics and kinetics during running. Seventy runners participated in this study. Three-dimensional marker positions and ground reaction forces were recorded with an 8-camera motion analysis system and a force plate while subjects ran along a 25-m runway at a speed of 4m/s. Knee abduction, hip rotation and toe-out angles, frontal plane lever arm at the knee, internal knee abduction moment and impulse, ground reaction forces and the medio-lateral distance from the ankle joint center to the center of pressure (AJC-CoP) were quantified. The findings of this study indicate that greater hip external rotation angles were associated with greater toe-out angles, longer AJC-CoP distances, smaller internal knee abduction impulses with shorter frontal plane lever arms and greater knee abduction angles. Thus, there appears to exist a conflict between kinematic and kinetic risk factors of PFP, and hip external rotation angle may be a key factor to control frontal plane knee joint kinematics and kinetics. These results may help provide an appropriate manipulation and/or intervention on running style to reduce the risk of PFP. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schreiner, S.; Paschal, C.B.; Galloway, R.L.

Four methods of producing maximum intensity projection (MIP) images were studied and compared. Three of the projection methods differ in the interpolation kernel used for ray tracing. The interpolation kernels include nearest neighbor interpolation, linear interpolation, and cubic convolution interpolation. The fourth projection method is a voxel projection method that is not explicitly a ray-tracing technique. The four algorithms` performance was evaluated using a computer-generated model of a vessel and using real MR angiography data. The evaluation centered around how well an algorithm transferred an object`s width to the projection plane. The voxel projection algorithm does not suffer from artifactsmore » associated with the nearest neighbor algorithm. Also, a speed-up in the calculation of the projection is seen with the voxel projection method. Linear interpolation dramatically improves the transfer of width information from the 3D MRA data set over both nearest neighbor and voxel projection methods. Even though the cubic convolution interpolation kernel is theoretically superior to the linear kernel, it did not project widths more accurately than linear interpolation. A possible advantage to the nearest neighbor interpolation is that the size of small vessels tends to be exaggerated in the projection plane, thereby increasing their visibility. The results confirm that the way in which an MIP image is constructed has a dramatic effect on information contained in the projection. The construction method must be chosen with the knowledge that the clinical information in the 2D projections in general will be different from that contained in the original 3D data volume. 27 refs., 16 figs., 2 tabs.« less

Direct numerical simulation of stochastically forced laminar plane couette flow: peculiarities of hydrodynamic fluctuations.

PubMed

Khujadze, G; Oberlack, M; Chagelishvili, G

2006-07-21

The background of three-dimensional hydrodynamic (vortical) fluctuations in a stochastically forced, laminar, incompressible, plane Couette flow is simulated numerically. The fluctuating field is anisotropic and has well pronounced peculiarities: (i) the hydrodynamic fluctuations exhibit nonexponential, transient growth; (ii) fluctuations with the streamwise characteristic length scale about 2 times larger than the channel width are predominant in the fluctuating spectrum instead of streamwise constant ones; (iii) nonzero cross correlations of velocity (even streamwise-spanwise) components appear; (iv) stochastic forcing destroys the spanwise reflection symmetry (inherent to the linear and full Navier-Stokes equations in a case of the Couette flow) and causes an asymmetry of the dynamical processes.

US EPA OPTIMAL WELL LOCATOR (OWL): A SCREENING TOOL FOR EVALUATING LOCATIONS OF MONITORING WELLS

EPA Science Inventory

The Optimal Well Locator (OWL): uses linear regression to fit a plane to the elevation of the water table in monitoring wells in each round of sampling. The slope of the plane fit to the water table is used to predict the direction and gradient of ground water flow. Along with ...

Differential InP HEMT MMIC Amplifiers Embedded in Waveguides

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka; Schlecht, Erich; Samoska, Lorene

2009-01-01

Monolithic microwave integrated-circuit (MMIC) amplifiers of a type now being developed for operation at frequencies of hundreds of gigahertz contain InP high-electron-mobility transistors (HEMTs) in a differential configuration. The differential configuration makes it possible to obtain gains greater than those of amplifiers having the single-ended configuration. To reduce losses associated with packaging, the MMIC chips are designed integrally with, and embedded in, waveguide packages, with the additional benefit that the packages are compact enough to fit into phased transmitting and/or receiving antenna arrays. Differential configurations (which are inherently balanced) have been used to extend the upper limits of operating frequencies of complementary metal oxide/semiconductor (CMOS) amplifiers to the microwave range but, until now, have not been applied in millimeter- wave amplifier circuits. Baluns have traditionally been used to transform from single-ended to balanced configurations, but baluns tend to be lossy. Instead of baluns, finlines are used to effect this transformation in the present line of development. Finlines have been used extensively to drive millimeter- wave mixers in balanced configurations. In the present extension of the finline balancing concept, finline transitions are integrated onto the affected MMICs (see figure). The differential configuration creates a virtual ground within each pair of InP HEMT gate fingers, eliminating the need for inductive vias to ground. Elimination of these vias greatly reduces parasitic components of current and the associated losses within an amplifier, thereby enabling more nearly complete utilization of the full performance of each transistor. The differential configuration offers the additional benefit of multiplying (relative to the single-ended configuration) the input and output impedances of each transistor by a factor of four, so that it is possible to use large transistors that would otherwise have prohibitively low impedances. Yet another advantage afforded by the virtual ground of the differential configuration is elimination of the need for a ground plane and, hence, elimination of the need for back-side metallization of the MMIC chip. In turn, elimination of the back-side metallization simplifies fabrication, reduces parasitic capacitances, and enables mounting of the MMIC in the electric-field plane ("E-plane") of a waveguide. E-plane mounting is consistent with (and essential for the utility of) the finline configuration, in which transmission lines lie on a dielectric sheet in the middle of a broad side of the waveguide. E-plane mounting offers a combination of low loss and ease of assembly because no millimeter-wave wire bonds or transition substrates are required. Moreover, because there is no ground plane behind the MMIC, the impedance for the detrimental even (single-ended) mode is high, suppressing coupling to that mode. Still another advantage of E-plane mounting is that the fundamental waveguide mode is inherently differential, eliminating the need for a balun to excite the differential mode.

Boundary layer models for calving marine outlet glaciers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoof, Christian; Davis, Andrew D.; Popa, Tiberiu V.

We consider the flow of marine-terminating outlet glaciers that are laterally confined in a channel of prescribed width. In that case, the drag exerted by the channel side walls on a floating ice shelf can reduce extensional stress at the grounding line. If ice flux through the grounding line increases with both ice thickness and extensional stress, then a longer shelf can reduce ice flux by decreasing extensional stress. Consequently, calving has an effect on flux through the grounding line by regulating the length of the shelf. In the absence of a shelf, it plays a similar role by controllingmore » the above-flotation height of the calving cliff. Using two calving laws, one due to Nick et al. (2010) based on a model for crevasse propagation due to hydrofracture and the other simply asserting that calving occurs where the glacier ice becomes afloat, we pose and analyse a flowline model for a marine-terminating glacier by two methods: direct numerical solution and matched asymptotic expansions. The latter leads to a boundary layer formulation that predicts flux through the grounding line as a function of depth to bedrock, channel width, basal drag coefficient, and a calving parameter. By contrast with unbuttressed marine ice sheets, we find that flux can decrease with increasing depth to bedrock at the grounding line, reversing the usual stability criterion for steady grounding line location. Stable steady states can then have grounding lines located on retrograde slopes. We show how this anomalous behaviour relates to the strength of lateral versus basal drag on the grounded portion of the glacier and to the specifics of the calving law used.« less

Boundary layer models for calving marine outlet glaciers

DOE PAGES

Schoof, Christian; Davis, Andrew D.; Popa, Tiberiu V.

2017-10-05

We consider the flow of marine-terminating outlet glaciers that are laterally confined in a channel of prescribed width. In that case, the drag exerted by the channel side walls on a floating ice shelf can reduce extensional stress at the grounding line. If ice flux through the grounding line increases with both ice thickness and extensional stress, then a longer shelf can reduce ice flux by decreasing extensional stress. Consequently, calving has an effect on flux through the grounding line by regulating the length of the shelf. In the absence of a shelf, it plays a similar role by controllingmore » the above-flotation height of the calving cliff. Using two calving laws, one due to Nick et al. (2010) based on a model for crevasse propagation due to hydrofracture and the other simply asserting that calving occurs where the glacier ice becomes afloat, we pose and analyse a flowline model for a marine-terminating glacier by two methods: direct numerical solution and matched asymptotic expansions. The latter leads to a boundary layer formulation that predicts flux through the grounding line as a function of depth to bedrock, channel width, basal drag coefficient, and a calving parameter. By contrast with unbuttressed marine ice sheets, we find that flux can decrease with increasing depth to bedrock at the grounding line, reversing the usual stability criterion for steady grounding line location. Stable steady states can then have grounding lines located on retrograde slopes. We show how this anomalous behaviour relates to the strength of lateral versus basal drag on the grounded portion of the glacier and to the specifics of the calving law used.« less

International Aerospace and Ground Conference on Lightning and Static Electricity (8th): Lightning Technology Roundup, held at Fort Worth, Texas on 21-23 June 1983.

DTIC Science & Technology

1983-06-01

fighter aircraft. The entire test bed is from testing of a representative digital supported above the ground plane by non - control system(s)l e.g... control and Increased systems Integration a. Raw data must be collected and Introduce new requirements for protection, experimental setups and An accurate...presented, several possible solutions to the grounding prob! - are suggested. All rely on establishing initial ground contact through a controlled non -zero

Emission spectroscopy and laser-induced fluorescence measurements on the plume from a 1-kW arcjet operated on simulated ammonia

NASA Technical Reports Server (NTRS)

Ruyten, Wilhelmus M.; Burtner, D.; Keefer, Dennis

1993-01-01

Spectroscopic and laser-induced fluorescence measurements were performed on the exhaust plume from a 1 kW NASA Lewis arcjet, operated on simulated ammonia. In particular, emissions were analyzed from the Balmer lines of atomic hydrogen and from one of the rotational bands of the NH radical. The laser-induced fluorescence measurements were performed on the Balmer-alpha line of atomic hydrogen. We find that exit plane temperatures are in the range 1500 to 3500 K and that the electron density upstream of the exit plane is on the order of 1.5 x 10(exp 14)/cu cm as determined by the Stark width of the Balmer-alpha line. Both emission spectroscopy and laser-induced fluorescence were used to measure the plume velocities of atomic hydrogen. Using either technique, velocities on the order of 4 km/sec were found at the exit plane and significant acceleration of the flow was observed in the first 2 mm beyond the exit plane. This result indicates that the design of the arcjet nozzle may not be optimum.

Role of out-of-plane dielectric thickness in the electrostatic simulation of atomically thin lateral junctions

NASA Astrophysics Data System (ADS)

Nipane, Ankur; Zhang, Yefei; Teherani, James T.

2018-06-01

Two-dimensional materials enable novel electronic and optoelectronic devices due to their unique properties. Device modeling plays a fundamental role in developing these novel devices by providing insights into the underlying physics. In this work, we present the dramatic impact of the simulated out-of-plane dielectric thickness on the electrostatics of lateral junctions formed from atomically thin materials. We show that unlike bulk junctions, the boundary conditions on the edges of the simulation region significantly affect the electrostatics of two-dimensional (2D) lateral junctions by modifying the out-of-plane electric field. We also present an intuitive understanding of the Neumann boundary conditions imposed on the boundaries of the simulation region. The Neumann boundary conditions alter the intended simulation by generating reflections of the device across the boundaries. Finally, we derive a minimal dielectric thickness for a symmetrically doped 2D lateral p-n junction, above which the out-of-plane simulation region boundaries minimally affect the simulated electric field, electrostatic potential, and depletion width of the junction.

Comparative study on hydrostatic strain, stress and dislocation density of Al{sub 0.3}Ga{sub 0.7}N/GaN heterostructure before and after a-Si{sub 3}N{sub 4} passivation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinara, Syed Mukulika, E-mail: smdinara.iit@gmail.com; Jana, Sanjay Kr.; Mukhopadhyay, Partha

2015-08-28

The hydrostatic strain, stress and dislocation densities were comparatively analyzed before and after passivation of amorphous silicon nitride (a-Si{sub 3}N{sub 4}) layer on Al{sub 0.3}Ga{sub 0.7}N/GaN heterostructure by nondestructive high resolution x-ray diffraction (HRXRD) technique. The crystalline quality, in-plane and out-of plane strain were evaluated from triple-axis (TA) (ω-2θ) diffraction profile across the (002) reflection plane and double-axis (DA) (ω-2θ) glancing incidence (GI) diffraction profile across (105) reflection plane. The hydrostatic strain and stress of Al{sub 0.3}Ga{sub 0.7}N barrier layer were increased significantly after passivation and both are tensile in nature. The dislocation density of GaN was also analyzed andmore » no significant change was observed after passivation of the heterostructure. The crystalline quality was not degraded after passivation on the heterostructure confirmed by the full-width-half-maximum (FWHM) analysis.« less

Chiral Lagrangian with Heavy Quark-Diquark Symmetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jie Hu; Thomas Mehen

2005-11-29

We construct a chiral Lagrangian for doubly heavy baryons and heavy mesons that is invariant under heavy quark-diquark symmetry at leading order and includes the leading O(1/m{sub Q}) symmetry violating operators. The theory is used to predict the electromagnetic decay width of the J=3/2 member of the ground state doubly heavy baryon doublet. Numerical estimates are provided for doubly charm baryons. We also calculate chiral corrections to doubly heavy baryon masses and strong decay widths of low lying excited doubly heavy baryons.

Polarization-dependent thin-film wire-grid reflectarray for terahertz waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Tiaoming; School of Information Science and Engineering, Lanzhou University, Lanzhou 730000; Upadhyay, Aditi

2015-07-20

A thin-film polarization-dependent reflectarray based on patterned metallic wire grids is realized at 1 THz. Unlike conventional reflectarrays with resonant elements and a solid metal ground, parallel narrow metal strips with uniform spacing are employed in this design to construct both the radiation elements and the ground plane. For each radiation element, a certain number of thin strips with an identical length are grouped to effectively form a patch resonator with equivalent performance. The ground plane is made of continuous metallic strips, similar to conventional wire-grid polarizers. The structure can deflect incident waves with the polarization parallel to the stripsmore » into a designed direction and transmit the orthogonal polarization component. Measured radiation patterns show reasonable deflection efficiency and high polarization discrimination. Utilizing this flexible device approach, similar reflectarray designs can be realized for conformal mounting onto surfaces of cylindrical or spherical devices for terahertz imaging and communications.« less

Characteristics of the wire biconical antenna used for EMC measurements

NASA Astrophysics Data System (ADS)

Austin, Brian A.; Fourie, Andre P. C.

1991-08-01

The characteristics of a wire biconical antenna that determine its antenna factor were computed by using the method of moments code NEC-2. A fairly extensive validation exercise was conducted from which a suitable computer model was derived. The input impedance, gain, and radiation patterns of the antenna were computed for special cases where the biconical antenna is used above a conducting ground plane for open-field EMC (electromagnetic compatibility) testing. The effects of height above the ground plane and polarization of the antenna on these parameters were found and the antenna factor was corrected for them. The current distribution along the antenna elements was also examined, and it was found that significant pattern distortion can occur at some frequencies when a horizontal wire biconical antenna is used close to the ground. These results will allow this broadband antenna to be used with confidence in applications where previously only resonant dipoles were specified.

Quantum Hall ferromagnets and transport properties of buckled Dirac materials

NASA Astrophysics Data System (ADS)

Luo, Wenchen; Chakraborty, Tapash

2015-10-01

We study the ground states and low-energy excitations of a generic Dirac material with spin-orbit coupling and a buckling structure in the presence of a magnetic field. The ground states can be classified into three types under different conditions: SU(2), easy-plane, and Ising quantum Hall ferromagnets. For the SU(2) and the easy-plane quantum Hall ferromagnets there are goldstone modes in the collective excitations, while all the modes are gapped in an Ising-type ground state. We compare the Ising quantum Hall ferromagnet with that of bilayer graphene and present the domain-wall solution at finite temperatures. We then specify the phase transitions and transport gaps in silicene in Landau levels 0 and 1. The phase diagram depends strongly on the magnetic field and the dielectric constant. We note that there exist triple points in the phase diagrams in Landau level N =1 that could be observed in experiments.

Research and development on performance models of thermal imaging systems

NASA Astrophysics Data System (ADS)

Wang, Ji-hui; Jin, Wei-qi; Wang, Xia; Cheng, Yi-nan

2009-07-01

Traditional ACQUIRE models perform the discrimination tasks of detection (target orientation, recognition and identification) for military target based upon minimum resolvable temperature difference (MRTD) and Johnson criteria for thermal imaging systems (TIS). Johnson criteria is generally pessimistic for performance predict of sampled imager with the development of focal plane array (FPA) detectors and digital image process technology. Triangle orientation discrimination threshold (TOD) model, minimum temperature difference perceived (MTDP)/ thermal range model (TRM3) Model and target task performance (TTP) metric have been developed to predict the performance of sampled imager, especially TTP metric can provides better accuracy than the Johnson criteria. In this paper, the performance models above are described; channel width metrics have been presented to describe the synthesis performance including modulate translate function (MTF) channel width for high signal noise to ration (SNR) optoelectronic imaging systems and MRTD channel width for low SNR TIS; the under resolvable questions for performance assessment of TIS are indicated; last, the development direction of performance models for TIS are discussed.

Pulse stuttering as a remedy for aliased ground backscatter

NASA Astrophysics Data System (ADS)

Bowhill, S. A.

1983-12-01

An algorithm that aides in the removal of ground scatter from low frequency Mesosphere, Stratosphere, Troposphere (MST) radar signals is examined. The unwanted ground scatter is shown as a sequence of velocity plots which are almost typical at the various altitudes. The interpulse period is changed in a cyclic way, thereby destroying the coherence of the unwanted signal. The interpulse period must be changed by an amount at least equal to the transmitted pulse width, and optimum performance is obtained when the number of different interpulse period occupies a time span greater than the coherence time of the unwanted signal. Since a 20-msec pulse width is used, it was found convenient to cycle through 50 pulses, the interpulse period changing from 2 msec to 3 msec during the 1/8-second time. This particular pattern of interpulse periods was provided by a software radar controller. With application of this algorithm, the unwanted scatter signal becomes incoherent from one pulse to the next, and therefore is perceived as noise by the coherent integrator and correlator.

Pulse stuttering as a remedy for aliased ground backscatter

NASA Technical Reports Server (NTRS)

Bowhill, S. A.

1983-01-01

An algorithm that aides in the removal of ground scatter from low frequency Mesosphere, Stratosphere, Troposphere (MST) radar signals is examined. The unwanted ground scatter is shown as a sequence of velocity plots which are almost typical at the various altitudes. The interpulse period is changed in a cyclic way, thereby destroying the coherence of the unwanted signal. The interpulse period must be changed by an amount at least equal to the transmitted pulse width, and optimum performance is obtained when the number of different interpulse period occupies a time span greater than the coherence time of the unwanted signal. Since a 20-msec pulse width is used, it was found convenient to cycle through 50 pulses, the interpulse period changing from 2 msec to 3 msec during the 1/8-second time. This particular pattern of interpulse periods was provided by a software radar controller. With application of this algorithm, the unwanted scatter signal becomes incoherent from one pulse to the next, and therefore is perceived as noise by the coherent integrator and correlator.

Finite slice analysis (FINA) of sliced and velocity mapped images on a Cartesian grid

NASA Astrophysics Data System (ADS)

Thompson, J. O. F.; Amarasinghe, C.; Foley, C. D.; Rombes, N.; Gao, Z.; Vogels, S. N.; van de Meerakker, S. Y. T.; Suits, A. G.

2017-08-01

Although time-sliced imaging yields improved signal-to-noise and resolution compared with unsliced velocity mapped ion images, for finite slice widths as encountered in real experiments there is a loss of resolution and recovered intensities for the slow fragments. Recently, we reported a new approach that permits correction of these effects for an arbitrarily sliced distribution of a 3D charged particle cloud. This finite slice analysis (FinA) method utilizes basis functions that model the out-of-plane contribution of a given velocity component to the image for sequential subtraction in a spherical polar coordinate system. However, the original approach suffers from a slow processing time due to the weighting procedure needed to accurately model the out-of-plane projection of an anisotropic angular distribution. To overcome this issue we present a variant of the method in which the FinA approach is performed in a cylindrical coordinate system (Cartesian in the image plane) rather than a spherical polar coordinate system. Dubbed C-FinA, we show how this method is applied in much the same manner. We compare this variant to the polar FinA method and find that the processing time (of a 510 × 510 pixel image) in its most extreme case improves by a factor of 100. We also show that although the resulting velocity resolution is not quite as high as the polar version, this new approach shows superior resolution for fine structure in the differential cross sections. We demonstrate the method on a range of experimental and synthetic data at different effective slice widths.

Comparing esthetic smile perceptions among laypersons with and without orthodontic treatment experience and dentists

PubMed Central

An, Seong-Mu; Choi, Sun-Young; Chung, Young-Wook; Jang, Tae-Ho

2014-01-01

Objective The purpose of this study was to examine whether orthodontic treatment experience affects the individual's perception of smile esthetics and to evaluate differences among orthodontically treated laypersons, non-treated laypersons, and dentists by using computerized image alterations. Methods A photograph of a woman's smile was digitally altered using a software image editing program. The alterations involved gingival margin height, crown width and length, incisal plane canting, and dental midline of the maxillary anterior teeth. Three groups of raters (orthodontically treated laypersons, non-treated laypersons, and dentists) evaluated the original and altered images using a visual analog scale. Results The threshold for detecting changes in maxillary central incisor gingival margin height among laypersons was 1.5 mm; the threshold of dentists, who were more perceptive, was 1.0 mm. For maxillary lateral incisor crown width and height, the threshold of all three groups was 3.0 mm. Canting of the incisal plane was perceived when the canting was 3.0 mm among non-treated laypersons, 2.0 mm among treated laypersons, and 1.0 mm among dentists. Non-treated laypersons could not perceive dental midline shifts; however, treated laypersons and dentists perceived them when the shift was ≥ 3.0 mm. Conclusions Laypersons with and without orthodontic treatment experience and dentists have different perceptions of smile esthetics. Orthodontically treated laypersons were more critical than non-treated laypersons regarding incisal plane canting and dental midline shifts. Based on these findings, it is suggested that orthodontic treatment experience improved the esthetic perceptions of laypersons. PMID:25473645

A Comprehensive Search for Gamma-Ray Lines in the First Year of Data from the INTEGRAL Spectrometer

NASA Technical Reports Server (NTRS)

Teegarden, B. J.; Watanabe, K.

2006-01-01

Gamma-ray lines are produced in nature by a variety of different physical processes. They can be valuable astrophysical diagnostics providing information the may be unobtainable by other means. We have carried out an extensive search for gamma-ray lines in the first year of public data from the Spectrometer (SPI) on the INTEGRAL mission. INTEGRAL has spent a large fraction of its observing time in the Galactic Plane with particular concentration in the Galactic Center (GC) region (approximately 3 Msec in the first year). Hence the most sensitive search regions are in the Galactic Plane and Center. The phase space of the search spans the energy range 20-8000 keV, and line widths from 0-1000 keV (FWHM) and includes both diffuse and point-like emission. We have searched for variable emission on time scales down to approximately 1000 sec. Diffuse emission has been searched for on a range of different spatial scales from approximately 20 degrees (the approximate field-of-view of the spectrometer) up to the entire Galactic Plane. Our search procedures were verified by the recovery of the known gamma-ray lines at 511 keV and 1809 keV at the appropriate intensities and significances. We find no evidence for any previously unknown gamma-ray lines. The upper limits range from a few x10(exp -5) per square centimeter per second to a few x10(exp -3) per square centimeter per second depending on line width, energy and exposure. Comparison is made between our results and various prior predictions of astrophysical lines

Steeply dipping heaving bedrock, Colorado: Part 1 - Heave features and physical geological framework

USGS Publications Warehouse

Noe, D.C.; Higgins, J.D.; Olsen, H.W.

2007-01-01

Differentially heaving bedrock has caused severe damage near the Denver metropolitan area. This paper describes heave-feature morphologies, the underlying bedrock framework, and their inter-relationship. The heave features are linear to curvilinear and may attain heights of 0.7 m (2.4 ft), widths of 58 m (190 ft), and lengths of 1,067 m (3,500 ft). They are nearly symmetrical to highly asymmetrical in cross section, with width-to-height ratios of 45:1 to 400:1, and most are oriented parallel with the mountain front. The bedrock consists of Mesozoic sedimentary formations having dip angles of 30 degrees to vertical to overturned. Mixed claystone-siltstone bedding sequences up to 36-m (118-ft) thick are common in the heave-prone areas, and interbeds of bentonite, limestone, or sandstone may be present. Highly fractured zones of weathered to variably weathered claystone extend to depths of 19.5 to 22.3 m (64 to 73 ft). Fracture spacings are 0.1 to 0.2 m (0.3 to 0.7 ft) in the weathered and variably weathered bedrock and up to 0.75 m (2.5 ft) in the underlying, unweathered bedrock. Curvilinear shear planes in the weathered claystone show thrust or reverse offsets up to 1.2 m (3.9 ft). Three associations between heave-feature morphologies and the geological framework are recognized: (1) Linear, symmetrical to asymmetrical heaves are associated with primary bedding composition changes. (2) Linear, highly asymmetrical heaves are associated with shear planes along bedding. (3) Curvi-linear, highly asymmetrical heaves are associated with bedding-oblique shear planes.

Fabrication and convergent X-ray nanobeam diffraction characterization of submicron-thickness SrTiO 3 crystalline sheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tilka, J. A.; Park, J.; Sampson, K. C.

The creation of thin SrTiO3 crystals from (001)-oriented SrTiO3 bulk single crystals using focused ion beam milling techniques yields sheets with submicron thickness and arbitrary orientation within the (001) plane. Synchrotron x-ray nanodiffraction rocking curve widths of these SrTiO3 sheets are less than 0.02 degrees, less than a factor of two larger than bulk SrTiO3, making these crystals suitable substrates for epitaxial thin film growth. The change in the rocking curve width is sufficiently small that we deduce that dislocations are not introduced into the SrTiO3 sheets. Observed lattice distortions are consistent with a low concentration of point defects.

Cleaved-edge-overgrowth nanogap electrodes.

PubMed

Luber, Sebastian M; Bichler, Max; Abstreiter, Gerhard; Tornow, Marc

2011-02-11

We present a method to fabricate multiple metal nanogap electrodes of tailored width and distance in parallel, on the cleaved plane of a GaAs/AlGaAs heterostructure. The three-dimensional patterned structures are obtained by a combination of molecular-beam-epitaxial regrowth on a crystal facet, using the cleaved-edge-overgrowth (CEO) method, and subsequent wet selective etching and metallization steps. SEM and AFM studies reveal smooth and co-planar electrodes of width and distance of the order of 10 nm. Preliminary electrical characterization indicates electrical gap insulation in the 100 MΩ range with kΩ lead resistance. We propose our methodology to realize multiple electrode geometries that would allow investigation of the electrical conductivity of complex nanoscale objects such as branched organic molecules.

Hard X-ray multilayer zone plate with 25-nm outermost zone width

NASA Astrophysics Data System (ADS)

Takano, H.; Sumida, K.; Hirotomo, H.; Koyama, T.; Ichimaru, S.; Ohchi, T.; Takenaka, H.; Kagoshima, Y.

2017-06-01

We have improved the performance of a previously reported multilayer zone plate by reducing its outermost zone width, using the same multilayer materials (MoSi2 and Si) and fabrication technique. The focusing performance was evaluated at the BL24XU of SPring-8 using 20-keV X-rays. The line spread function (LSF) in the focal plane was measured using a dark-field knife-edge scan method, and the point spread function was obtained from the LSF through a tomographic reconstruction principle. The spatial resolution was estimated to be 30 nm, which is in relatively good agreement with the calculated diffraction-limited value of 25 nm, while the measured diffraction efficiency of the +1st order was 24%.

Intraband light absorption by holes in InGaAsP/InP quantum wells

NASA Astrophysics Data System (ADS)

Pavlov, N. V.; Zegrya, G. G.

2018-03-01

A microscopic analysis of the mechanism of intraband radiation absorption by holes with their transition to a spin-split band for quantum wells based on InGaAsP/InP solid solutions is performed within the framework of the four-band Kane model. The calculation is made for two polarizations of the incident radiation: along the crystal growth axis and in the plane of the quantum well. It is shown that this process can be the main mechanism of internal radiation losses for quantum well lasers. It is also shown that the dependence of the absorption coefficient on the width of the quantum well has a maximum at a well width from 40 to 60 A.

Lower Extremity Energy Absorption and Biomechanics During Landing, Part II: Frontal-Plane Energy Analyses and Interplanar Relationships

PubMed Central

Norcross, Marc F.; Lewek, Michael D.; Padua, Darin A.; Shultz, Sandra J.; Weinhold, Paul S.; Blackburn, J. Troy

2013-01-01

Context: Greater sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing is consistent with sagittal-plane biomechanics that likely increase anterior cruciate ligament (ACL) loading, but it does not appear to influence frontal-plane biomechanics. We do not know whether frontal-plane INI EA is related to high-risk frontal-plane biomechanics. Objective: To compare biomechanics among INI EA groups, determine if women are represented more in the high group, and evaluate interplanar INI EA relationships. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: Participants included 82 (41 men, 41 women; age = 21.0 ± 2.4 years, height = 1.74 ± 0.10 m, mass = 70.3 ± 16.1 kg) healthy, physically active volunteers. Intervention(s): We assessed landing biomechanics with an electromagnetic motion-capture system and force plate. Main Outcome Measure(s): We calculated frontal- and sagittal-plane total, hip, knee, and ankle INI EA. Total frontal-plane INI EA was used to create high, moderate, and low tertiles. Frontal-plane knee and hip kinematics, peak vertical and posterior ground reaction forces, and peak internal knee-varus moment (pKVM) were identified and compared across groups using 1-way analyses of variance. We used a χ2 analysis to evaluate male and female allocation to INI EA groups. We used simple, bivariate Pearson product moment correlations to assess interplanar INI EA relationships. Results: The high–INI EA group exhibited greater knee valgus at ground contact, hip adduction at pKVM, and peak hip adduction than the low–INI EA group (P < .05) and greater peak knee valgus, pKVM, and knee valgus at pKVM than the moderate– (P < .05) and low– (P < .05) INI EA groups. Women were more likely than men to be in the high–INI EA group (χ2 = 4.909, P = .03). Sagittal-plane knee and frontal-plane hip INI EA (r = 0.301, P = .006) and sagittal-plane and frontal-plane ankle INI EA were associated (r = 0.224, P = .04). No other interplanar INI EA relationships were found (P > .05). Conclusions: Greater frontal-plane INI EA was associated with less favorable frontal-plane biomechanics that likely result in greater ACL loading. Women were more likely than men to use greater frontal-plane INI EA. The magnitudes of sagittal- and frontal-plane INI EA were largely independent. PMID:23944381

Benchmark solution for vibrations from a moving point source in a tunnel embedded in a half-space

NASA Astrophysics Data System (ADS)

Yuan, Zonghao; Boström, Anders; Cai, Yuanqiang

2017-01-01

A closed-form semi-analytical solution for the vibrations due to a moving point load in a tunnel embedded in a half-space is given in this paper. The tunnel is modelled as an elastic hollow cylinder and the ground surrounding the tunnel as a linear viscoelastic material. The total wave field in the half-space with a cylindrical hole is represented by outgoing cylindrical waves and down-going plane waves. To apply the boundary conditions on the ground surface and at the tunnel-soil interface, the transformation properties between the plane and cylindrical wave functions are employed. The proposed solution can predict the ground vibration from an underground railway tunnel of circular cross-section with a reasonable computational effort and can serve as a benchmark solution for other computational methods. Numerical results for the ground vibrations on the free surface due to a moving constant load and a moving harmonic load applied at the tunnel invert are presented for different load velocities and excitation frequencies. It is found that Rayleigh waves play an important role in the ground vibrations from a shallow tunnel.

Single-Slit Diffraction: Transitioning from Geometric Optics to the Fraunhofer Regime

ERIC Educational Resources Information Center

Panuski, Christopher L.; Mungan, Carl E.

2016-01-01

Suppose a red laser beam (of wavelength ? equal to 0.660 µm) is expanded using an optical telescope into a collimated, approximately plane wave that is 5.68 mm in diameter. Pass that beam through a tall rectangular slit whose width "a" is gradually reduced from 3.30 to 0.100 mm. Look at its image on a screen located at a distance…

Molecular dynamics of lipid bilayers studied by incoherent quasi-elastic neutron scattering

NASA Astrophysics Data System (ADS)

König, S.; Pfeiffer, W.; Bayerl, T.; Richter, D.; Sackmann, E.

1992-08-01

Molecular motions in highly oriented multilayers of dipalmitoylphosphatidylcholine were studied as a function of temperature and hydration using incoherent quasi-elastic neutron scattering (QENS). The short range diffusive motions of the lipid molecules and the chain/headgroup dynamics were evaluated : 1) by measurement of the dependence of the elastic incoherent structure factor (EISF), the line-width Γ and the dynamic structure factors on the scattering vector Q for two orientations of the sample. The orientations were chosen such that the scattering vecto Q was either predominantly perpendicular or parallel to the membrane normal ; 2) by comparing data from protonated and chain deuterated lipids and 3) by the use of instruments of different energy resolution (i.e. time-of-flight and backscattering spectrometers exploring time regimes of 10^{-13} s to 10^{-11} s and 10^{-11} s to 10^{-9} s respectively). In the fluid phase the time-of-flight spectra revealed a restricted isotropic in-plane and out-of-plane diffusion of the hydrocarbon chain and headgroup protons. The mean displacements range from ≈ 0.6 Å for methylene protons near the glycerol backbone to 7 Å for protons near the chain ends. These values are obtained for a water content of 23 wt%. The values are somewhat increased at 30wt% of water. Measurements of the temperature variation of the EISF and the line-width Γ revealed a remarkably high degree of chain dynamics in the gel (L{β '})-phase. The total elastic intensity as observed with the backscattering instrument showed that L{α}-L{β '}-phase transition is only well expressed at Q-values around 1 Å^{-1}, while the number and mobility of the chain defects characterized at Q≈ 2 Å^{-1} (possibly gtg-kinks) increase continuously between 2 °C and 70 °C. In the time regime explored by the backscattering instrument, motions of the whole lipid molecules are also seen. It was interpreted in terms of a superposition of local in-plane and out-of-plane diffusion and lateral diffusional jumps between adjacent sites as predicted by the free volume model. For a sample containing 12 wt% of water at 60 °C the diffusion coefficient for the out-of-plane motion is D^{allel}=6× 10^{-6} cm2/s with an amplitude of 2.25 Å. In-plane the diffusion coefficients range from D_{min}^{perp}=1.5× 10^{-7} cm2/s to D_{max}^{perp}=6× 10^{-6} cm2/s. The lateral diffusion coefficient is D_lat=9.7× 10^{-8} cm2/s in reasonable agreement with FRAP measurements. The strong increase of the lateral mobility with increasing water content yielded an exponential law for the variation of the diffusion coefficient with excess area per lipid (i.e. hydration) in agreement with the free volume model. The out-of-plane motion is characterized by an amplitude of about 0.5 Å in the time-of-flight time regime and of 2-3 Å in the backscattering time regime. The origin of this discrepancy could be the thermally excited membrane undulations since their relaxation times of ≈ 3× 10^{-9} s (obtained in a separate spin-echo study) agree roughly with the reciprocal line-width of 2.5× 10^{-9} s for the backscattering instrument at Qto 0. The time-of-flight result of 0.5 Å can be attributed to a dynamic surface roughness.

Research and design of an optical system of biochemical analyzer based on the narrow-band pass filter

NASA Astrophysics Data System (ADS)

Xiao, Ze-xin; Chen, Kuan

2008-03-01

Biochemical analyzer is one of the important instruments in the clinical diagnosis, and its optical system is the important component. The operation of this optical system can be regard as three parts. The first is transforms the duplicate colored light as the monochromatic light. The second is transforms the light signal of the monochromatic, which have the information of the measured sample, as the electric signal by use the photoelectric detector. And the last is to send the signal to data processing system by use the control system. Generally, there are three types monochromators: prism, optical grating and narrow-band pass filter. Thereinto, the narrow-band pass filter were widely used in the semi-auto biochemical analyzer. Through analysed the principle of biochemical analyzer base on the narrow-band pass filter, we known that the optical has three features. The first is the optical path of the optical system is a non- imaging system. The second, this system is wide spectrum region that contain visible light and ultraviolet spectrum. The third, this is a little aperture and little field monochromatic light system. Therefore, design idea of this optical system is: (1) luminous energy in the system less transmission loss; (2) detector coupled to the luminous energy efficient; mainly correct spherical aberration. Practice showed the point of Image quality evaluation: (1) dispersion circle diameter equal the receiving device pixel effective width of 125%, and the energy distribution should point target of 80% of energy into the receiving device pixel width of the effective diameter in this dispersion circle; (2) With MTF evaluation, the requirements in 20lp/ mm spatial frequency, the MTF values should not be lower than 0.6. The optical system should be fit in with ultraviolet and visible light width spectrum, and the detector image plane can but suited the majority visible light spectrum when by defocus optimization, and the image plane of violet and ultraviolet excursion quite large. Traditional biochemical analyzer optical design not fully consider this point, the authors introduce a effective image plane compensation measure innovatively, it greatly increased the reception efficiency of the violet and ultraviolet.

T-SDN architecture for space and ground integrated optical transport network

NASA Astrophysics Data System (ADS)

Nie, Kunkun; Hu, Wenjing; Gao, Shenghua; Chang, Chengwu

2015-11-01

Integrated optical transport network is the development trend of the future space information backbone network. The space and ground integrated optical transport network(SGIOTN) may contain a variety of equipment and systems. Changing the network or meeting some innovation missions in the network will be an expensive implement. Software Defined Network(SDN) provides a good solution to flexibly adding process logic, timely control states and resources of the whole network, as well as shielding the differences of heterogeneous equipment and so on. According to the characteristics of SGIOTN, we propose an transport SDN architecture for it, with hierarchical control plane and data plane composed of packet networks and optical transport networks.

Method for fabricating fan-fold shielded electrical leads

DOEpatents

Rohatgi, R.R.; Cowan, T.E.

1994-12-27

Fan-folded electrical leads made from copper cladded Kapton, for example, with the copper cladding on one side serving as a ground plane and the copper cladding on the other side being etched to form the leads. The Kapton is fan folded with the leads located at the bottom of the fan-folds. Electrical connections are made by partially opening the folds of the fan and soldering, for example, the connections directly to the ground plane and/or the lead. The fan folded arrangement produces a number of advantages, such as electrically shielding the leads from the environment, is totally non-magnetic, and has a very low thermal conductivity, while being easy to fabricate. 3 figures.

Laser communications technology with airborne platform

NASA Astrophysics Data System (ADS)

Jiang, Huilin; Liu, Guojun; Yin, Fuchang; Liu, Zhi

2006-01-01

Space laser communications (SLC) possess a series of advantages, such as higher data rates, large capacity of information, very good secrecy, et al. So SLC has been attracting great attention the throughout western and developed countries. USA, EU and Japan are making great efforts in establishing space-air-ground integrated communications network, with satellites, planes or ground vehicles as platforms. China has also carried out laser communication research activities in recent years. Changchun University of Science and technology (CUST) has been doing research studies on space laser communications with plane as the platform, and relatively thorough study on some of the key technologies such as airborne lasercom terminal design. The present paper will address some of these topics.

Compact Low Frequency Radio Antenna

DOEpatents

Punnoose, Ratish J.

2008-11-11

An antenna is disclosed that comprises a pair of conductive, orthogonal arches and a pair of conductive annular sector plates, wherein adjacent legs of each arch are fastened to one of the annular sector plates and the opposite adjacent pair of legs is fastened to the remaining annular sector plate. The entire antenna structure is spaced apart from a conductive ground plane by a thin dielectric medium. The antenna is driven by a feed conduit passing through the conductive ground plane and dielectric medium and attached to one of the annular sector plates, wherein the two orthogonal arched act as a pair of crossed dipole elements. This arrangement of elements provides a radiation pattern that is largely omni-directional above the horizon.

Thin conformal antenna array for microwave power conversions

NASA Technical Reports Server (NTRS)

Dickinson, R. M. (Inventor)

1978-01-01

A structure of a circularly polarized, thin conformal, antenna array which may be mounted integrally with the skin of an aircraft employs microstrip elliptical elements and interconnecting feed lines spaced from a circuit ground plane by a thin dielectric layer. The feed lines are impedance matched to the elliptical antenna elements by selecting a proper feedpoint inside the periphery of the elliptical antenna elements. Diodes connected between the feed lines and the ground plane rectify the microwave power, and microstrip filters (low pass) connected in series with the feed lines provide dc current to a microstrip bus. Low impedance matching strips are included between the elliptical elements and the rectifying and filtering elements.

Bandwidth broadening of a graphene-based circular polarization converter by phase compensation.

PubMed

Gao, Xi; Yang, Wanli; Cao, Weiping; Chen, Ming; Jiang, Yannan; Yu, Xinhua; Li, Haiou

2017-10-02

We present a broadband tunable circular polarization converter composed of a single graphene sheet patterned with butterfly-shaped holes, a dielectric spacer, and a 7-layer graphene ground plane. It can convert a linearly polarized wave into a circularly polarized wave in reflection mode. The polarization converter can be dynamically tuned by varying the Fermi energy of the single graphene sheet. Furthermore, the 7-layer graphene acting as a ground plane can modulate the phase of its reflected wave by controlling the Femi energy, which provides constructive interference condition at the surface of the single graphene sheet in a broad bandwidth and therefore significantly broadens the tunable bandwidth of the proposed polarization converter.

Magnetic response of brickwork artificial spin ice

NASA Astrophysics Data System (ADS)

Park, Jungsik; Le, Brian L.; Sklenar, Joseph; Chern, Gia-Wei; Watts, Justin D.; Schiffer, Peter

2017-07-01

We have investigated the response of brickwork artificial spin ice to an applied in-plane magnetic field through magnetic force microscopy, magnetotransport measurements, and micromagnetic simulations. We find that, by sweeping an in-plane applied field from saturation to zero in a narrow range of angles near one of the principal axes of the lattice, the moments of the system fall into an antiferromagnetic ground state in both connected and disconnected structures. Magnetotransport measurements of the connected lattice exhibit unique signatures of this ground state. Also, modeling of the magnetotransport demonstrates that the signal arises at vertex regions in the structure, confirming behavior that was previously seen in transport studies of kagome artificial spin ice.

Method for fabricating fan-fold shielded electrical leads

DOEpatents

Rohatgi, Rajeev R.; Cowan, Thomas E.

1994-01-01

Fan-folded electrical leads made from copper cladded Kapton, for example, with the copper cladding on one side serving as a ground plane and the copper cladding on the other side being etched to form the leads. The Kapton is fan folded with the leads located at the bottom of the fan-folds. Electrical connections are made by partially opening the folds of the fan and soldering, for example, the connections directly to the ground plane and/or the lead. The fan folded arrangement produces a number of advantages, such as electrically shielding the leads from the environment, is totally non-magnetic, and has a very low thermal conductivity, while being easy to fabricate.

Fan-fold shielded electrical leads

DOEpatents

Rohatgi, R.R.; Cowan, T.E.

1996-06-11

Disclosed are fan-folded electrical leads made from copper cladded Kapton, for example, with the copper cladding on one side serving as a ground plane and the copper cladding on the other side being etched to form the leads. The Kapton is fan folded with the leads located at the bottom of the fan-folds. Electrical connections are made by partially opening the folds of the fan and soldering, for example, the connections directly to the ground plane and/or the lead. The fan folded arrangement produces a number of advantages, such as electrically shielding the leads from the environment, is totally non-magnetic, and has a very low thermal conductivity, while being easy to fabricate. 3 figs.

Specific absorption rate analysis of broadband mobile antenna with negative index metamaterial

NASA Astrophysics Data System (ADS)

Alam, Touhidul; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

2016-03-01

This paper presents a negative index metamaterial-inspired printed mobile wireless antenna that can support most mobile applications such as GSM, UMTS, Bluetooth and WLAN frequency bands. The antenna consists of a semi-circular patch, a 50Ω microstrip feed line and metamaterial ground plane. The antenna occupies a very small space of 37 × 47 × 0.508 mm3, making it suitable for mobile wireless application. The perceptible novelty shown in this proposed antenna is that reduction of specific absorption rate using the negative index metamaterial ground plane. The proposed antenna reduced 72.11 and 75.53 % of specific absorption rate at 1.8 and 2.4 GHz, respectively.

Visualizing Sungai Batu Ancient River, Lembah Bujang Archeology Site, Kedah – Malaysia using 3-D Resistivity Imaging

NASA Astrophysics Data System (ADS)

Yusoh, R.; Saad, R.; Saidin, M.; Muhammad, S. B.; Anda, S. T.; Ashraf, M. A. M.; Hazreek, Z. A. M.

2018-04-01

Sungai Batu at lembah bujang has become an interest spot for archeologist since it was discover as earliest entrepot in history of Malaysia. It is believe that there was a large lost river near the ancient jetty remain. Ground resistivity method was implement with large coverage area to locate the ancient river direction. Eleven ground resistivity survey line was carry out using SAS4000 equipment and wenner-schlumberger array was applied for measurement. Ground resistivity method was used to detect the alluvial deposit made by the ancient river deposition. The ground resistivity data were produce in 2D image and presented in 3D contour map for various selected depth by using Rockwork 15 and Surfer 8 software to visualize the alluvial deposits area. The results from the survey has found the appearance of sedimentation formation due to low resistivity value (0 – 330 ohm.m) was found near the existing river. However, the width of alluvial deposition was 1400 m which too wide for river width unless it was a deposition happen form age to age by movement of river meander. It’s conclude that the river was still at the same direction and its direction was change due to sediment dumping factor waking it shifting to the east.

U.S. EPA OPTIMAL WELL LOCATOR (OWL): A SCREENING TOOL FOR EVALUATING LOCATIONS OF MONITORING WELLS (ROCKY GAP, MD)

EPA Science Inventory

The Optimal Well Locator (OWL): uses linear regression to fit a plane to the elevation of the water table in monitoring wells in each round of sampling. The slope of the plane fit to the water table is used to predict the direction and gradient of ground water flow. Along with ...

Ankle Dorsiflexion Displacement During Landing is Associated With Initial Contact Kinematics but not Joint Displacement.

PubMed

Begalle, Rebecca L; Walsh, Meghan C; McGrath, Melanie L; Boling, Michelle C; Blackburn, J Troy; Padua, Darin A

2015-08-01

The ankle, knee, and hip joints work together in the sagittal plane to absorb landing forces. Reduced sagittal plane motion at the ankle may alter landing strategies at the knee and hip, potentially increasing injury risk; however, no studies have examined the kinematic relationships between the joints during jump landings. Healthy adults (N = 30; 15 male, 15 female) performed jump landings onto a force plate while three-dimensional kinematic data were collected. Joint displacement values were calculated during the loading phase as the difference between peak and initial contact angles. No relationship existed between ankle dorsiflexion displacement during landing and three-dimensional knee and hip displacements. However, less ankle dorsiflexion displacement was associated with landing at initial ground contact with larger hip flexion, hip internal rotation, knee flexion, knee varus, and smaller plantar flexion angles. Findings of the current study suggest that restrictions in ankle motion during landing may contribute to contacting the ground in a more flexed position but continuing through little additional motion to absorb the landing. Transverse plane hip and frontal plane knee positioning may also occur, which are known to increase the risk of lower extremity injury.

The orbital ground state of the azide-substrate complex of human heme oxygenase is an indicator of distal H-bonding: implications for the enzyme mechanism.

PubMed

Ogura, Hiroshi; Evans, John P; Peng, Dungeng; Satterlee, James D; Ortiz de Montellano, Paul R; La Mar, Gerd N

2009-04-14

The active site electronic structure of the azide complex of substrate-bound human heme oxygenase 1 (hHO) has been investigated by (1)H NMR spectroscopy to shed light on the orbital/spin ground state as an indicator of the unique distal pocket environment of the enzyme. Two-dimensional (1)H NMR assignments of the substrate and substrate-contact residue signals reveal a pattern of substrate methyl contact shifts that places the lone iron pi-spin in the d(xz) orbital, rather than the d(yz) orbital found in the cyanide complex. Comparison of iron spin relaxivity, magnetic anisotropy, and magnetic susceptibilities argues for a low-spin, (d(xy))(2)(d(yz),d(xz))(3), ground state in both azide and cyanide complexes. The switch from singly occupied d(yz) for the cyanide to d(xz) for the azide complex of hHO is shown to be consistent with the orbital hole determined by the azide pi-plane in the latter complex, which is approximately 90 degrees in-plane rotated from that of the imidazole pi-plane. The induction of the altered orbital ground state in the azide relative to the cyanide hHO complex, as well as the mean low-field bias of methyl hyperfine shifts and their paramagnetic relaxivity relative to those in globins, indicates that azide exerts a stronger ligand field in hHO than in the globins, or that the distal H-bonding to azide is weaker in hHO than in globins. The Asp140 --> Ala hHO mutant that abolishes activity retains the unusual WT azide complex spin/orbital ground state. The relevance of our findings for other HO complexes and the HO mechanism is discussed.

The orbital ground state of the azide-substrate complex of human heme oxygenase is an indicator of distal H-bonding: Implications for the enzyme mechanism‡

PubMed Central

Ogura, Hiroshi; Evans, John P.; Peng, Dungeng; Satterlee, James D.; de Montellano, Paul R. Ortiz; Mar, Gerd N. La

2009-01-01

The active site electronic structure of the azide complex of substrate-bound human heme oxygenase-1, (hHO) has been investigated by 1H NMR spectroscopy to shed light on the orbital/spin ground state as an indicator of the unique distal pocket environment of the enzyme. 2D 1H NMR assignments of the substrate and substrate-contact residue signals reveal a pattern of substrate methyl contact shifts, that places the lone iron π-spin in the dxz orbital, rather than the dyz orbital found in the cyanide complex. Comparison of iron spin relaxivity, magnetic anisotropy and magnetic susceptibilities argues for a low-spin, (dxy)2(dyz,dxz)3, ground state in both azide and cyanide complexes. The switch from singly-occupied dyz for the cyanide to dxz for the azide complex of hHO is shown to be consistent with the orbital hole determined by the azide π-plane in the latter complex, which is ∼90° in-plane rotated from that of the imidazole π-plane. The induction of the altered orbital ground state in the azide relative to the cyanide hHO complex, as well as the mean low-field bias of methyl hyperfine shifts and their paramagnetic relaxivity relative to those in globins, indicate that azide exerts a stronger ligand field in hHO than in the globins, or that the distal H-bonding to azide is weaker in hHO than in globins. The Asp140 → Ala hHO mutant that abolishes activity retains the unusual WT azide complex spin/orbital ground state. The relevance of our findings for other HO complexes and the HO mechanism is discussed. PMID:19243105

Morphometric differences of nasopalatine canal based on 3D classifications: descriptive analysis on CBCT.

PubMed

Fernández-Alonso, A; Suárez-Quintanilla, J A; Rapado-González, O; Suárez-Cunqueiro, María Mercedes

2015-09-01

This descriptive retrospective study analyzed differences among sagittal, coronal and axial NC groups based on the dimensions of nasopalatine canal (NC), buccal bone plate (BBP) and palatal bone plate (PBP) to canal. Measurements were made on 224 CBCTs for NC, BBP and PBP on the three anatomic planes at three levels: level 1, when the incisive foramen is completely closed on the axial plane; level 2, at the midpoint of NC length (NCL) on the sagittal plane; and level 3, at the foramina of Stenson on the sagittal plane. ANOVA tests with post hoc tests were used. The intraclass correlation coefficient and Kappa test were used for evaluating the intraobserver agreement. Regarding coronal classification, these significant differences were found: BBP length (BL)level 1 was lower for the two parallel canals group; PBP length (PL)level 1 was lower for single canal group; and NCL was lower for Y-type canal group. Regarding axial classification, these significant differences were found: LPlevel 1 was lower for 3.1-3 group; PBP width (PW)level 3 was the greatest for 3.1-3; and LPlevel 3 was lower for 1.1. Presurgical evaluation with CBCT in premaxillae region should include analysis on coronal and axial planes and not only on sagittal plane seeing as morphometric differences were found on coronal and axial planes. Following the morphological coronal classification, two parallel canals presented a higher NCL, a higher LP and a lower LV at inferior edge of alveolar ridge.

Turbulent Plane Wakes Subjected to Successive Strains

NASA Technical Reports Server (NTRS)

Rogers, Michael M.

2003-01-01

Six direct numerical simulations of turbulent time-evolving strained plane wakes have been examined to investigate the response of a wake to successive irrotational plane strains of opposite sign. The orientation of the applied strain field has been selected so that the flow is the time-developing analogue of a spatially developing wake evolving in the presence of either a favourable or an adverse streamwise pressure gradient. The magnitude of the applied strain rate a is constant in time t until the total strain e(sup at) reaches about four. At this point, a new simulation is begun with the sign of the applied strain being reversed (the original simulation is continued as well). When the total strain is reduced back to its original value of one, yet another simulation is begun with the sign of the strain being reversed again back to its original sign. This process is done for both initially "favourable" and initially "adverse" strains, providing simulations for each of these strain types from three different initial conditions. The evolution of the wake mean velocity deficit and width is found to be very similar for all the adversely strained cases, with both measures rapidly achieving exponential growth at the rate associated with the cross-stream expansive strain e(sup at). In the "favourably" strained cases, the wake widths approach a constant and the velocity deficits ultimately decay rapidly as e(sup -2at). Although all three of these cases do exhibit the same asymptotic exponential behaviour, the time required to achieve this is longer for the cases that have been previously adversely strained (by at approx. equals 1). These simulations confirm the generality of the conclusions drawn in Rogers (2002) regarding the response of plane wakes to strain. The evolution of strained wakes is not consistent with the predictions of classical self-similar analysis; a more general equilibrium similarity solution is required to describe the results. At least for the cases considered here, the wake Reynolds number and the ratio of the turbulent kinetic energy to the square of the wake mean velocity deficit are determined nearly entirely by the total strain. For these measures the order in which the strains are applied does not matter and the changes brought about by the strain are nearly reversible. The wake mean velocity deficit and width, on the other hand, differ by about a factor of three when the total strain returns to one, depending on whether the wake was first "favourably" or "adversely" strained. The strain history is important for predicting the evolution of these quantities.

The Structure of Chariklo’s Rings from Stellar Occultations

NASA Astrophysics Data System (ADS)

Bérard, D.; Sicardy, B.; Camargo, J. I. B.; Desmars, J.; Braga-Ribas, F.; Ortiz, J.-L.; Duffard, R.; Morales, N.; Meza, E.; Leiva, R.; Benedetti-Rossi, G.; Vieira-Martins, R.; Gomes Júnior, A.-R.; Assafin, M.; Colas, F.; Dauvergne, J.-L.; Kervella, P.; Lecacheux, J.; Maquet, L.; Vachier, F.; Renner, S.; Monard, B.; Sickafoose, A. A.; Breytenbach, H.; Genade, A.; Beisker, W.; Bath, K.-L.; Bode, H.-J.; Backes, M.; Ivanov, V. D.; Jehin, E.; Gillon, M.; Manfroid, J.; Pollock, J.; Tancredi, G.; Roland, S.; Salvo, R.; Vanzi, L.; Herald, D.; Gault, D.; Kerr, S.; Pavlov, H.; Hill, K. M.; Bradshaw, J.; Barry, M. A.; Cool, A.; Lade, B.; Cole, A.; Broughton, J.; Newman, J.; Horvat, R.; Maybour, D.; Giles, D.; Davis, L.; Paton, R. A.; Loader, B.; Pennell, A.; Jaquiery, P.-D.; Brillant, S.; Selman, F.; Dumas, C.; Herrera, C.; Carraro, G.; Monaco, L.; Maury, A.; Peyrot, A.; Teng-Chuen-Yu, J.-P.; Richichi, A.; Irawati, P.; De Witt, C.; Schoenau, P.; Prager, R.; Colazo, C.; Melia, R.; Spagnotto, J.; Blain, A.; Alonso, S.; Román, A.; Santos-Sanz, P.; Rizos, J.-L.; Maestre, J.-L.; Dunham, D.

2017-10-01

Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo’s system in order to better characterize the physical properties of the ring and main body. Here, we use 12 successful occulations by Chariklo observed between 2014 and 2016. They provide ring profiles (physical width, opacity, edge structure) and constraints on the radii and pole position. Our new observations are currently consistent with the circular ring solution and pole position, to within the ±3.3 km formal uncertainty for the ring radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal significant width variations from ˜5 to 7.5 km. The width of the fainter ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and outer edges of C1R are consistent with infinitely sharp boundaries, with typical upper limits of one kilometer for the transition zone between the ring and empty space. No constraint on the sharpness of C2R’s edges is available. A 1σ upper limit of ˜20 m is derived for the equivalent width of narrow (physical width < 4 km) rings up to distances of 12,000 km, counted in the ring plane.

Influence of the width and cross-sectional shape of major connectors of maxillary dentures on the accuracy of speech production.

PubMed

Wada, Junichiro; Hideshima, Masayuki; Inukai, Shusuke; Matsuura, Hiroshi; Wakabayashi, Noriyuki

2014-01-01

To investigate the effects of the width and cross-sectional shape of the major connectors of maxillary dentures located in the middle area of the palate on the accuracy of phonetic output of consonants using an originally developed speech recognition system. Nine adults (4 males and 5 females, aged 24-26 years) with sound dentition were recruited. The following six sounds were considered: [∫i], [t∫i], [ɾi], [ni], [çi], and [ki]. The experimental connectors were fabricated to simulate bars (narrow, 8-mm width) and plates (wide, 20-mm width). Two types of cross-sectional shapes in the sagittal plane were specified: flat and plump edge. The appearance ratio of phonetic segment labels was calculated with the speech recognition system to indicate the accuracy of phonetic output. Statistical analysis was conducted using one-way ANOVA and Tukey's test. The mean appearance ratio of correct labels (MARC) significantly decreased for [ni] with the plump edge (narrow connector) and for [ki] with both the flat and plump edge (wide connectors). For [çi], the MARCs tended to be lower with flat plates. There were no significant differences for the other consonants. The width and cross-sectional shape of the connectors had limited effects on the articulation of consonants at the palate. © 2015 S. Karger AG, Basel.

VIEW OF MISSILE TUBE AT THE GROUND FLOOR LEVEL. VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF MISSILE TUBE AT THE GROUND FLOOR LEVEL. VIEW FACING SOUTH - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

VIEW OF MISSILE TUBE AT THE GROUND FLOOR LEVEL. VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF MISSILE TUBE AT THE GROUND FLOOR LEVEL. VIEW FACING EAST - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

VIEW OF WIDE STAIR TO SECOND FLOOR FROM GROUND FLOOR. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF WIDE STAIR TO SECOND FLOOR FROM GROUND FLOOR. VIEW FACING SOUTH - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

VIEW OF COMPRESSOR ROOM AT GROUND LEVEL SHOWING COMPRESSOR EQUIPMENT. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF COMPRESSOR ROOM AT GROUND LEVEL SHOWING COMPRESSOR EQUIPMENT. VIEW FACING SOUTH - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

Structural anisotropy of nonpolar and semipolar InN epitaxial layers

NASA Astrophysics Data System (ADS)

Darakchieva, V.; Xie, M.-Y.; Franco, N.; Giuliani, F.; Nunes, B.; Alves, E.; Hsiao, C. L.; Chen, L. C.; Yamaguchi, T.; Takagi, Y.; Kawashima, K.; Nanishi, Y.

2010-10-01

We present a detailed study of the structural characteristics of molecular beam epitaxy grown nonpolar InN films with a- and m-plane surface orientations on r-plane sapphire and (100) γ-LiAlO2, respectively, and semipolar (101¯1) InN grown on r-plane sapphire. The on-axis rocking curve (RC) widths were found to exhibit anisotropic dependence on the azimuth angle with minima at InN [0001] for the a-plane films, and maxima at InN [0001] for the m-plane and semipolar films. The different contributions to the RC broadening are analyzed and discussed. The finite size of the crystallites and extended defects are suggested to be the dominant factors determining the RC anisotropy in a-plane InN, while surface roughness and curvature could not play a major role. Furthermore, strategy to reduce the anisotropy and magnitude of the tilt and minimize defect densities in a-plane InN films is suggested. In contrast to the nonpolar films, the semipolar InN was found to contain two domains nucleating on zinc-blende InN(111)A and InN(111)B faces. These two wurtzite domains develop with different growth rates, which was suggested to be a consequence of their different polarity. Both, a- and m-plane InN films have basal stacking fault densities similar or even lower compared to nonpolar InN grown on free-standing GaN substrates, indicating good prospects of heteroepitaxy on foreign substrates for the growth of InN-based devices.

Contamination control device

DOEpatents

Clark, Robert M.; Cronin, John C.

1977-01-01

A contamination control device for use in a gas-insulated transmission bus consisting of a cylindrical center conductor coaxially mounted within a grounded cylindrical enclosure. The contamination control device is electrically connected to the interior surface of the grounded outer shell and positioned along an axial line at the lowest vertical position thereon. The contamination control device comprises an elongated metallic member having a generally curved cross-section in a first plane perpendicular to the axis of the bus and having an arcuate cross-section in a second plane lying along the axis of the bus. Each opposed end of the metallic member and its opposing sides are tapered to form a pair of generally converging and downward sloping surfaces to trap randomly moving conductive particles in the relatively field-free region between the metallic member and the interior surface of the grounded outer shell. The device may have projecting legs to enable the device to be spot welded to the interior of the grounded housing. The control device provides a high capture probability and prevents subsequent release of the charged particles after the capture thereof.

Strut and wall interference on jet-induced ground effects of a STOVL aircraft in hover

NASA Technical Reports Server (NTRS)

Kristy, Michael H.

1995-01-01

A small scale ground effect test rig was used to study the ground plane flow field generated by a STOVL aircraft in hover. The objective of the research was to support NASA-Ames Research Center planning for the Large Scale Powered Model (LSPM) test for the ARPA-sponsored ASTOVL program. Specifically, small scale oil flow visualization studies were conducted to make a relative assessment of the aerodynamic interference of a proposed strut configuration and a wall configuration on the ground plane stagnation line. A simplified flat plate model representative of a generic jet-powered STOVL aircraft was used to simulate the LSPM. Cold air jets were used to simulate both the lift fan and the twin rear engines. Nozzle Pressure Ratios were used that closely represented those used on the LSPM tests. The flow visualization data clearly identified a shift in the stagnation line location for both the strut and the wall configuration. Considering the experimental uncertainty, it was concluded that either the strut configuration o r the wall configuration caused only a minor aerodynamic interference.

Optimization of Planar Monopole Wideband Antenna for Wireless Communication System

PubMed Central

Moghavvemi, Mahmoud; Mahadi, Wan Nor Liza

2016-01-01

In this paper, a new compact wideband monopole antenna is presented for wireless communication applications. This antenna comprises of a new radiating patch, a new arc-shaped strip, microstrip feed line, and a notched ground plane. The proposed radiating patch is combined with a rectangular and semi-circular patch and is integrated with a partial ground plane to provide a wide impedance bandwidth. The new arc-shaped strip between the radiating patch and microstrip feed line creates an extra surface on the patch, which helps further widen the bandwidth. Inserting one step notch on the ground plane further enhances the bandwidth. The antenna has a compact size of 16×20×1.6mm3. The measured result indicated that the antenna achieves a 127% bandwidth at VSWR≤2, ranging from 4.9GHz to 22.1GHz. Stable radiation patterns with acceptable gain are achieved. Also, a measured bandwidth of 107.7% at VSWR≤1.5 (5.1-17GHz) is obtained, which is suitable for UWB outdoor propagation. This antenna is compatible with a good number of wireless standards, including UWB band, Wimax 5.4 GHz band, MVDDS (12.2–12.7GHz), and close range radar and satellite communication in the X-band (8-12GHz), and Ku band (12-18GHz). PMID:27992466

Optimization of Planar Monopole Wideband Antenna for Wireless Communication System.

PubMed

Shakib, Mohammed Nazmus; Moghavvemi, Mahmoud; Mahadi, Wan Nor Liza

2016-01-01

In this paper, a new compact wideband monopole antenna is presented for wireless communication applications. This antenna comprises of a new radiating patch, a new arc-shaped strip, microstrip feed line, and a notched ground plane. The proposed radiating patch is combined with a rectangular and semi-circular patch and is integrated with a partial ground plane to provide a wide impedance bandwidth. The new arc-shaped strip between the radiating patch and microstrip feed line creates an extra surface on the patch, which helps further widen the bandwidth. Inserting one step notch on the ground plane further enhances the bandwidth. The antenna has a compact size of 16×20×1.6mm3. The measured result indicated that the antenna achieves a 127% bandwidth at VSWR≤2, ranging from 4.9GHz to 22.1GHz. Stable radiation patterns with acceptable gain are achieved. Also, a measured bandwidth of 107.7% at VSWR≤1.5 (5.1-17GHz) is obtained, which is suitable for UWB outdoor propagation. This antenna is compatible with a good number of wireless standards, including UWB band, Wimax 5.4 GHz band, MVDDS (12.2-12.7GHz), and close range radar and satellite communication in the X-band (8-12GHz), and Ku band (12-18GHz).

Electromagnetic Scattering from Arbitrarily Shaped Aperture Backed by Rectangular Cavity Recessed in Infinite Ground Plane

NASA Technical Reports Server (NTRS)

Cockrell, C. R.; Beck, Fred B.

1997-01-01

The electromagnetic scattering from an arbitrarily shaped aperture backed by a rectangular cavity recessed in an infinite ground plane is analyzed by the integral equation approach. In this approach, the problem is split into two parts: exterior and interior. The electromagnetic fields in the exterior part are obtained from an equivalent magnetic surface current density assumed to be flowing over the aperture and backed by an infinite ground plane. The electromagnetic fields in the interior part are obtained in terms of rectangular cavity modal expansion functions. The modal amplitudes of cavity modes are determined by enforcing the continuity of the electric field across the aperture. The integral equation with the aperture magnetic current density as an unknown is obtained by enforcing the continuity of magnetic fields across the aperture. The integral equation is then solved for the magnetic current density by the method of moments. The electromagnetic scattering properties of an aperture backed by a rectangular cavity are determined from the magnetic current density. Numerical results on the backscatter radar cross-section (RCS) patterns of rectangular apertures backed by rectangular cavities are compared with earlier published results. Also numerical results on the backscatter RCS patterns of a circular aperture backed by a rectangular cavity are presented.

3-D model-based vehicle tracking.

PubMed

Lou, Jianguang; Tan, Tieniu; Hu, Weiming; Yang, Hao; Maybank, Steven J

2005-10-01

This paper aims at tracking vehicles from monocular intensity image sequences and presents an efficient and robust approach to three-dimensional (3-D) model-based vehicle tracking. Under the weak perspective assumption and the ground-plane constraint, the movements of model projection in the two-dimensional image plane can be decomposed into two motions: translation and rotation. They are the results of the corresponding movements of 3-D translation on the ground plane (GP) and rotation around the normal of the GP, which can be determined separately. A new metric based on point-to-line segment distance is proposed to evaluate the similarity between an image region and an instantiation of a 3-D vehicle model under a given pose. Based on this, we provide an efficient pose refinement method to refine the vehicle's pose parameters. An improved EKF is also proposed to track and to predict vehicle motion with a precise kinematics model. Experimental results with both indoor and outdoor data show that the algorithm obtains desirable performance even under severe occlusion and clutter.

Approximations useful for the prediction of electrostatic discharges for simple electrode geometries

NASA Technical Reports Server (NTRS)

Edmonds, L.

1986-01-01

The report provides approximations for estimating the capacitance and the ratio of electric field strength to potential for a certain class of electrode geometries. The geometry consists of an electrode near a grounded plane, with the electrode being a surface of revolution about the perpendicular to the plane. Some examples which show the accuracy of the capacitance estimate and the accuracy of the estimate of electric field over potential can be found in the appendix. When it is possible to estimate the potential of the electrode, knowing the ratio of electric field to potential will help to determine if an electrostatic discharge is likely to occur. Knowing the capacitance will help to determine the strength of the discharge (the energy released by it) if it does occur. A brief discussion of discharge mechanisms is given. The medium between the electrode and the grounded plane may be a neutral gas, a vacuum, or an unchanged homogeneous isotropic dielectric.

The Spin-Plane Double Probe Electric Field Instrument for MMS

NASA Astrophysics Data System (ADS)

Lindqvist, P.-A.; Olsson, G.; Torbert, R. B.; King, B.; Granoff, M.; Rau, D.; Needell, G.; Turco, S.; Dors, I.; Beckman, P.; Macri, J.; Frost, C.; Salwen, J.; Eriksson, A.; Åhlén, L.; Khotyaintsev, Y. V.; Porter, J.; Lappalainen, K.; Ergun, R. E.; Wermeer, W.; Tucker, S.

2016-03-01

The Spin-plane double probe instrument (SDP) is part of the FIELDS instrument suite of the Magnetospheric Multiscale mission (MMS). Together with the Axial double probe instrument (ADP) and the Electron Drift Instrument (EDI), SDP will measure the 3-D electric field with an accuracy of 0.5 mV/m over the frequency range from DC to 100 kHz. SDP consists of 4 biased spherical probes extended on 60 m long wire booms 90∘ apart in the spin plane, giving a 120 m baseline for each of the two spin-plane electric field components. The mechanical and electrical design of SDP is described, together with results from ground tests and calibration of the instrument.

The Relationship Between CME Properties in the CDAW, CACTUS and SEEDS Catalogs and ?25 MeV Solar Proton Event Intensities

NASA Astrophysics Data System (ADS)

Richardson, I. G.; von Rosenvinge, T. T.; Cane, H. V.

2013-12-01

The existence of a correlation between the intensity of solar energetic proton (SEP) events and the speed of the associated coronal mass ejection near the Sun is well known, and is often interpreted as evidence for particle acceleration at CME-driven shocks. However, this correlation is far from perfect and might be improved by taking other parameters into consideration (e.g., CME width). In studies of cycle 23 SEP events, values of CME speed, width and other parameters were typically taken from the CDAWWeb LASCO CME catalog. This is compiled 'by hand' from examination of LASCO images by experienced observers. Other automated LASCO CME catalogs have now been developed, e.g., CACTUS (Royal Observatory of Belgium) and SEEDS (George Mason University), but the basic CME parameters do not always agree with those from the CDAWweb catalog since they are not determined in the same way. For example the 'CME speed' might be measured at a specific position angle against the plane of the sky in one catalog, or be the average of speeds taken along the CME front in another. Speeds may also be based on linear or higher order fits to the coronagraph images. There will also be projection effects in these plane of the sky speeds. Similarly, CME widths can vary between catalogs and are dependent on how they are defined. For example, the CDAW catalog lists any CME that surrounds the occulting disk as a 'halo' (360 deg. width) CME even though the CME may be highly-asymmetric and originate from a solar event far from central meridian. Another catalog may give a smaller width for the same CME. The problem of obtaining the 'true' CME width is especially acute for assessing the relationship between CME width and SEP properties when using the CDAW catalog since a significant fraction, if not the majority, of the CMEs associated with major SEP events are reported to be halo CMEs. In principle, observations of CMEs from the STEREO A and B spacecraft, launched in late 2006, might be used to overcome some of these problems. In particular, a spacecraft in quadrature with the solar source of an SEP event should observe the 'true' width and speed of the associated CME. However, STEREO CME parameters are derived using the CACTUS method, and cannot be directly compared with the LASCO CDAW catalog values that have been so widely used for many years. In this study, we will examine the relationship between the properties of CMEs in various catalogs and the intensities of a large sample of particle events that include ˜25 MeV protons in cycles 23 and 24. In particular, we will compare the proton intensity-speed relationships obtained using the CDAW, CACTUS and SEEDS LASCO catalogs, and also using the CACTUS values from whichever spacecraft (STEREO A, B or SOHO) is best in quadrature with the solar event. We will also examine whether there is any correlation between the width of the CMEs in the automated catalogs and proton intensity, and whether a combination of CME speed and width might improve the correlation with proton intensity.

Magneto-transport Characterization of Thin Film In-plane and Cross-plane Conductivity

NASA Astrophysics Data System (ADS)

Tang, Yang; Grayson, Matthew

Thin films with highly anisotropic in-plane and cross-plane conductivities are widely used in devices, such as infrared emitters and detectors, and the proper magneto-transport characterization in both directions can reveal information about the doping density, impurities, carrier life times and band structure. This work introduces a novel method for deducing the complete anisotropic electrical conductivity tensor of such an anisotropic resistive layer atop a highly conducting bottom contact, which is a standard part of the device structure. Three strip-line contacts separated by a length scale comparable to the film thickness are applied atop the resistive thin film layer of interest, with the highly conducting back-plane as a back-contact. The potential distribution in the device is modeled, using both scaling and conformal transformation to minimize the calculated volume. As a proof of concept, triple strip-line devices for GaAs and GaAs/AlGaAs superlattice thin films are fabricated. To achieve narrow strip-line contacts with sub-micron scale widths, non-annealed Ni/Au contacts form ohmic contacts to a patterned n+-GaAs cap layer atop the anisotropic thin films. Preliminary experimental data will be presented as a validation of this method. Acknowledgment: Funded by AFOSR FA9550-15-1-0377 and AFOSR FA9550-15-1-0247.

Trapping two types of particles with a focused generalized Multi-Gaussian Schell model beam

NASA Astrophysics Data System (ADS)

Liu, Xiayin; Zhao, Daomu

2015-11-01

We numerically investigate the trapping effect of the focused generalized Multi-Gaussian Schell model (GMGSM) beam of the first kind which produces dark hollow beam profile at the focal plane. By calculating the radiation forces on the Rayleigh dielectric sphere in the focused GMGSM beam, we show that such beam can trap low-refractive-index particles at the focus, and simultaneously capture high-index particles at different positions of the focal plane. The trapping range and stability depend on the values of the beam index N and the coherence width. Under the same conditions, the low limits of the radius of low-index and high-index particles for stable trapping are indicated to be different.

Quantum-shutter approach to tunneling time scales with wave packets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, Norifumi; Garcia-Calderon, Gaston; Villavicencio, Jorge

2005-07-15

The quantum-shutter approach to tunneling time scales [G. Garcia-Calderon and A. Rubio, Phys. Rev. A 55, 3361 (1997)], which uses a cutoff plane wave as the initial condition, is extended to consider certain type of wave packet initial conditions. An analytical expression for the time-evolved wave function is derived. The time-domain resonance, the peaked structure of the probability density (as the function of time) at the exit of the barrier, originally found with the cutoff plane wave initial condition, is studied with the wave packet initial conditions. It is found that the time-domain resonance is not very sensitive to themore » width of the packet when the transmission process occurs in the tunneling regime.« less

A gait retraining system using augmented-reality to modify footprint parameters: Effects on lower-limb sagittal-plane kinematics.

PubMed

Bennour, Sami; Ulrich, Baptiste; Legrand, Thomas; Jolles, Brigitte M; Favre, Julien

2018-01-03

Improving lower-limb flexion/extension angles during walking is important for the treatment of numerous pathologies. Currently, these gait retraining procedures are mostly qualitative, often based on visual assessment and oral instructions. This study aimed to propose an alternative method combining motion capture and display of target footprints on the floor. The second objectives were to determine the error in footprint modifications and the effects of footprint modifications on lower-limb flexion/extension angles. An augmented-reality system made of an optoelectronic motion capture device and video projectors displaying target footprints on the floor was designed. 10 young healthy subjects performed a series of 27 trials, consisting of increased and decreased amplitudes in stride length, step width and foot progression angle. 11 standard features were used to describe and compare lower-limb flexion/extension angles among footprint modifications. Subjects became accustomed to walk on target footprints in less than 10 min, with mean (± SD) precision of 0.020 ± 0.002 m in stride length, 0.022 ± 0.006 m in step width, and 2.7 ± 0.6° in progression angle. Modifying stride length had significant effects on 3/3 hip, 2/4 knee and 4/4 ankle features. Similarly, step width and progression angle modifications affected 2/3 and 1/3 hip, 2/4 and 1/4 knee as well as 3/4 and 2/4 ankle features, respectively. In conclusion, this study introduced an augmented-reality method allowing healthy subjects to modify their footprint parameters rapidly and precisely. Walking with modified footprints changed lower-limb sagittal-plane kinematics. Further research is needed to design rehabilitation protocols for specific pathologies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Theoretical analysis of an oscillatory plane Poiseuille flow—A link to the design of vortex flow meter

NASA Astrophysics Data System (ADS)

Ma, Huai-Lung; Kuo, Cheng-Hsiung

2017-05-01

Theoretical analysis on an oscillatory plane Poiseuille flow is conducted in terms of a non-dimensional ratio (η) of the channel half-width to Stokes' layer thickness. The cyclic velocity profiles, the phase shifts and the magnitudes among the driving pressure gradient, the induced wall shear stress, and the volume flux are investigated. Also, the flow physics at a different ratio η is demonstrated. In this study, the mechanism of the driving pressure gradient and the oscillating volume flux is similar to and can be employed to demonstrate the slit flow in the application of the novel vortex flow meter using a slit cylinder as a shedder. When applied to the novel vortex flow meter, the non-dimensional ratio η can be expressed as the relation of the slit width ratio (S/D), the Strouhal number, and the Reynolds number. Finally, a range of η between 0.97 < η < 20 will be suggested for the vortex flow meter at the design stage. Large values of η are employed at a high Reynolds number, and small η is used for low Reynolds number applications. In the novel vortex flow meters, a cylinder with a normal axial slit of width (S) is employed as the shedder. Due to the primary lock-on, the process of vortex shedding synchronizes with the rhythm of slit flow leading to a stable shedding frequency. The value η is well correlated by the value of ηopt obtained by experiments and shows a one-to-one correspondence to the slit ratio at each Reynolds number. Once the design value of ηopt is determined, the optimal slit ratio can be estimated for a fixed applied Reynolds number at the design stage.

The pregnant "waddle": an evaluation of torso kinematics in pregnancy.

PubMed

McCrory, Jean L; Chambers, April J; Daftary, Ashi; Redfern, Mark S

2014-09-22

Although pregnant women are anecdotally said to "waddle" during gait, researchers have not quantified the kinematics of these gait alterations. The purpose of this study was to examine the effects of pregnancy on thoracic and pelvic kinematics during gait. Data were collected on 29 pregnant subjects in the mid-second and third trimesters and on 40 control women. Three-dimensional kinematic data were collected on subjects walking at their freely-chosen speed. Right foot heel-strike (RHS) and left foot toe-off (LTO) were determined from force plate data. Thoracic and pelvic angles at RHS, step width, mediolateral translation of the C7 and L4 vertebrae, and the ranges of motion (ROMs) of the thorax and pelvis over the gait stride were determined. A series of MANCOVAs were performed with trimester (second, third, and control) as the independent variable and velocity as the covariate (α=0.05). Post-hoc analyses were performed when appropriate. Increased lateral translation of the C7 and L4 vertebrae (third trimester>second trimester>control, p<0.05) was noted, accompanied by an increased step width in the third trimester (p=0.03). At heel strike, pregnant women had greater thoracic extension (third trimester>second trimester>control, p<0.05) and greater anterior pelvic tilt (third trimester>control; p<0.05). Sagittal plane thoracic ROM was less in the third trimester compared to controls (p<0.01). Pregnant women demonstrated a lateral shifting of the body during gait, which accompanied a greater step width. The increased thoracic extension and anterior pelvic tilt, along with decreased sagittal plane ROM are likely adaptations to increased abdominal size. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study of electrode pattern design for a CZT-based PET detector

PubMed Central

Gu, Y; Levin, C S

2014-01-01

We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3-D positioning Cadmium Zinc Telluride (CZT) photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 mm and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 ns to ~127.5 ns FWHM for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 ns to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips’ weighting functions, which indicated a stronger “small pixel” effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 V to −80 V w.r.t the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 μm vs. 100 μm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns. PMID:24786208

Skin penetration of silicon dioxide microneedle arrays.

PubMed

Kim, Sangchae; Shetty, S; Price, D; Bhansali, S

2006-01-01

Out-of-plane hollow silicon dioxide microneedle arrays were fabricated and investigated to determine their efficacy for transdermal applications. The fabrication process of the SiO2 microneedles is described, and mechanical fracture forces were investigated on microneedles with different geometrical dimensions. Biomechanical characterization of the microneedles was performed to specifically test for reliable stratum corneum and skin insertion by changing the regulatory parameters such as needle width and cross-section.

Domain wall motion in sub-100 nm magnetic wire

NASA Astrophysics Data System (ADS)

Siddiqui, Saima; Dutta, Sumit; Currivan, Jean Anne; Ross, Caroline; Baldo, Marc

2015-03-01

Nonvolatile memory devices such as racetrack memory rely on the manipulation of domain wall (DW) in magnetic nanowires, and scaling of these devices requires an understanding of domain wall behavior as a function of the wire width. Due to the increased importance of edge roughness and magnetostatic interaction, DW pinning increases dramatically as the wire dimensions decrease and stochastic behavior is expected depending on the distribution of pinning sites. We report on the field driven DW statistics in sub-100 nm wide nanowires made from Co films with very small edge roughness. The nanowires were patterned in the form of a set of concentric rings of 10 μm diameter. Two different width nanowires with two different spacings have been studied. The rings were first saturated in plane to produce onion states and then the DWs were translated in the wires using an orthogonal in-plane field. The position of the DWs in the nanowires was determined with magnetic force microscopy. From the positions of the DWs in the nanowires, the strength of the extrinsic pinning sites was identified and they follow two different distributions in two different types of nanowire rings. For the closely spaced wires, magnetostatic interactions led to correlated movement of DWs in neighboring wires. The implications of DW pinning and interaction in nanoscale DW devices will be discussed.

The Gamow-state description of the decay energy spectrum of neutron-unbound 25O

NASA Astrophysics Data System (ADS)

Id Betan, R. M.; de la Madrid, R.

2018-02-01

We show the feasibility of calculating the decay energy spectrum of neutron emitting nuclei within the Gamow-state description of resonances by obtaining the decay energy spectrum of 25O. We model this nucleus as a valence neutron interacting with an 24O inert core, and we obtain the resulting resonant energies, widths and decay energy spectra for the ground and first excited states. We also discuss the similarities and differences between the decay energy spectrum of a Gamow state and the Breit-Wigner distribution with energy-dependent width.

Workshop on Future Directions for Optical Information Processing.

DTIC Science & Technology

1981-03-01

h . The i reference point source simultaneously illuminates the i member of a family of n phase-encoding Aiffusers (e.g. shower glass , ground glass ...diffuser (ground glass ) section illuminated with a plane wave [35.37). The n(n-1) - 4(3) - 12 crosstalk terms have been distributed into the noise...for 2x2 input Fig. 6. Outnut of processor analogous to that array, l.Sx magnifier, ground glass diffuser of Fig. 5, but using spherical wavefront and

Housing Projects.

ERIC Educational Resources Information Center

Schmalz, Georgann

1985-01-01

Building specifications for birdhouses (nesting boxes) are given for 11 species (chickadee, titmouse, nuthatch, Carolina wren, house wren, downy woodpecker, hairy woodpecker, flicker, bluebird, screech owl, and wood duck) including length, width, depth, entrance diameter, and height above the ground. Pointers for construction, materials, and…

DETAIL OF MISSILE TUBE HATCH WITH MILLED FITTINGS AT GROUND ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL OF MISSILE TUBE HATCH WITH MILLED FITTINGS AT GROUND FLOOR LEVEL. VIEW FACING EAST - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

VIEW OF EQUIPMENT AT THE GROUND FLOOR LEVEL OF THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF EQUIPMENT AT THE GROUND FLOOR LEVEL OF THE MISSILE TUBE ROOM. VIEW FACING SOUTH - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

An orbiting multispectral scanner for overland and oceanographic applications.

NASA Technical Reports Server (NTRS)

Peacock, K.; Withrington, R. J.

1971-01-01

Description of the major features of a multispectral scanner designed to perform overland and oceanographic surveys from space. The instrument uses an image plane conical scanner and contains independent spectrometers for land and ocean applications. The overland spectrometer has a spatial resolution of 200 ft and has six spectral bands in the atmospheric windows between 0.5 and 2.4 microns. The oceanographic spectrometer has a spatial resolution of 1200 ft and possesses 24 spectral bands equally spaced and in registration over the wavelength range from 0.4 to 0.8 micron. A thermal band of 600-ft resolution is used with a spectral range from 10.5 to 12.6 microns. The swath width of the scan is 100 nautical miles from an altitude of 500 nautical miles. The system has two modes of operation which are selectable by ground command. The six bands of overland data plus the thermal band data can be transmitted, or the 24 bands of oceanographic data plus data from two of the overland bands and the thermal band can be transmitted. The performance is described by the minimum detectable reflectance difference and the effects of sun angle and target reflectivity variations are discussed. The sensitivity is related to the variation of the ocean reflectivity in the presence of chlorophyll and to typical agricultural targets.

A Three-Line Stereo Camera Concept for Planetary Exploration

NASA Technical Reports Server (NTRS)

Sandau, Rainer; Hilbert, Stefan; Venus, Holger; Walter, Ingo; Fang, Wai-Chi; Alkalai, Leon

1997-01-01

This paper presents a low-weight stereo camera concept for planetary exploration. The camera uses three CCD lines within the image plane of one single objective. Some of the main features of the camera include: focal length-90 mm, FOV-18.5 deg, IFOV-78 (mu)rad, convergence angles-(+/-)10 deg, radiometric dynamics-14 bit, weight-2 kg, and power consumption-12.5 Watts. From an orbit altitude of 250 km the ground pixel size is 20m x 20m and the swath width is 82 km. The CCD line data is buffered in the camera internal mass memory of 1 Gbit. After performing radiometric correction and application-dependent preprocessing the data is compressed and ready for downlink. Due to the aggressive application of advanced technologies in the area of microelectronics and innovative optics, the low mass and power budgets of 2 kg and 12.5 Watts is achieved, while still maintaining high performance. The design of the proposed light-weight camera is also general purpose enough to be applicable to other planetary missions such as the exploration of Mars, Mercury, and the Moon. Moreover, it is an example of excellent international collaboration on advanced technology concepts developed at DLR, Germany, and NASA's Jet Propulsion Laboratory, USA.

Evaluation of the relationship between the static measurement of transverse arch flexibility of the forefoot and gait parameters in healthy subjects.

PubMed

Kondo, Takashi; Muneta, Takeshi; Fukui, Tsutomu

2017-03-01

[Purpose] To investigate the relationship between the static measurement of the transverse arch of the forefoot, using a 3-dimensional (3D) foot scanner, and kinetics and kinematics of gait parameters in the sagittal plane. [Subjects and Methods] Twenty healthy subjects participated in this study. The transverse arch of the forefoot was measured under three conditions as follows: condition 1, sitting; condition 2, standing; and condition 3, foot forward and lower leg tilting anteriorly to the maximum position with heel contact. Gait parameters were recorded using a 3D motion analysis system and force plate. Correlation coefficients between TAF for each comparison of conditions and gait parameters were calculated using the Spearman correlation analysis. [Results] Rates of the transverse arch of the forefoot width and height between condition 2 and condition 3 were significantly correlated with the anterior and posterior component of ground reaction forces, the hip joint extension angle, and the ankle plantar flexion moment. [Conclusion] Our study's findings indicated that increased stiffness of the transverse arch of the forefoot was related to the increase in ankle plantar moment, and decreased stiffness of the transverse arch of the forefoot was related to the increase in hip joint extension angle during gait.

Evaluation of the relationship between the static measurement of transverse arch flexibility of the forefoot and gait parameters in healthy subjects

PubMed Central

Kondo, Takashi; Muneta, Takeshi; Fukui, Tsutomu

2017-01-01

[Purpose] To investigate the relationship between the static measurement of the transverse arch of the forefoot, using a 3-dimensional (3D) foot scanner, and kinetics and kinematics of gait parameters in the sagittal plane. [Subjects and Methods] Twenty healthy subjects participated in this study. The transverse arch of the forefoot was measured under three conditions as follows: condition 1, sitting; condition 2, standing; and condition 3, foot forward and lower leg tilting anteriorly to the maximum position with heel contact. Gait parameters were recorded using a 3D motion analysis system and force plate. Correlation coefficients between TAF for each comparison of conditions and gait parameters were calculated using the Spearman correlation analysis. [Results] Rates of the transverse arch of the forefoot width and height between condition 2 and condition 3 were significantly correlated with the anterior and posterior component of ground reaction forces, the hip joint extension angle, and the ankle plantar flexion moment. [Conclusion] Our study’s findings indicated that increased stiffness of the transverse arch of the forefoot was related to the increase in ankle plantar moment, and decreased stiffness of the transverse arch of the forefoot was related to the increase in hip joint extension angle during gait. PMID:28356622

Ten Deg Off-Axis Test for Shear Properties in Fiber Composites

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Sinclair, J. H.

1977-01-01

A combined theoretical and experimental investigation was conducted to assess the suitability of the 10 deg off-axis tensile test specimen for the intralaminar shear characterization of unidirectional composites. Composite mechanics, a combined-stress failure criterion, and a finite variation across the specimen width and the relative stress and strain magnitudes at the 10 deg plane. Strain gages were used to measure the strain variation across the specimen width at specimen midlength and near the end tabs. Specimens from Mod-I/epoxy, T-300/epoxy, and S-glass/epoxy were used in the experimental program. It was found that the 10 deg off-axis tensile test specimen is suitable for intralaminar shear characterization, and it is recommended that it should be considered as a possible standard test specimen for such a characterization.

Factors associated with mandibular third molar eruption and impaction.

PubMed

Tsai, Hung-Huey

2005-01-01

A retrospective study, using panoramic radiographs, was conducted on 152 Taiwanese (72 males and 80 females) to investigate mandibular third molar eruption and impaction. The following measurements were made: inclinations and mesiodistal crown widths of the mandibular molars, vertical and horizontal spaces between the distal surface of the second molar and the anterior surface of the ramus, lengths and widths of the mandibular ramus and body, the ramus inclination, the mandibular plane angle, and the mandibular gonial angle. Differences between non-impaction and impaction groups were studied, and the variables were analyzed with multivariate discriminatory analysis. Significant differences between the two groups were found; variables describing spaces between the anterior of the ramus and the distal of the mandibular second molar and tooth size appeared to be the primary contributors to the differences observed.

Flattening and manipulation of the electronic structure of h-BN/Rh(111) nanomesh upon Sn intercalation

NASA Astrophysics Data System (ADS)

Sugiyama, Yuya; Bernard, Carlo; Okuyama, Yuma; Ideta, Shin-ichiro; Tanaka, Kiyohisa; Greber, Thomas; Hirahara, Toru

2018-06-01

We have deposited Sn on corrugated hexagonal boron nitride (h-BN) nanomeshs formed on Rh(111) and found that Sn atoms are intercalated between h-BN and Rh, flattening the h-BN. Our reflection high-energy electron diffraction (RHEED) analysis showed that the average in-plane lattice constant of h-BN increases due to the loss of the corrugation. Furthermore, electronic structure measurements based on angle-resolved photoemission spectroscopy (ARPES) showed that the h-BN π band width increases significantly while the σ band width does not change as much. These behaviors were partly different from previous reports on the intercalation of h-BN/Rh system. Our results offer a novel, simple method to control the electronic structure of h-BN.

An adaptive array antenna for mobile satellite communications

NASA Technical Reports Server (NTRS)

Milne, Robert

1988-01-01

The adaptive array is linearly polarized and consists essentially of a driven lambda/4 monopole surrounded by an array of parasitic elements all mounted on a ground plane of finite size. The parasitic elements are all connected to ground via pin diodes. By applying suitable bias voltages, the desired parasitic elements can be activated and made highly reflective. The directivity and pointing of the antenna beam can be controlled in both the azimuth and elevation planes using high speed digital switching techniques. The antenna RF losses are neglible and the maximum gain is close to the theoretical value determined by the effective aperture size. The antenna is compact, has a low profile, is inexpensive to manufacture and can handle high transmitter power.

Study of a Flexible Low Profile Tunable Dipole Antenna Using Barium Strontium Titanate Varactors

NASA Technical Reports Server (NTRS)

Cure, David; Weller, Thomas; Miranda, Felix A.

2014-01-01

In this paper a flexible low profile dipole antenna using a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells is presented. The varactor chips were placed only along one dimension of the FSS to avoid the use of vias and simplify the DC bias network. The antenna uses overlapping metallic plates that resemble fish scales as a ground plane to improve the flexibility of the multi-material stack structure. The measured data of the antenna demonstrate tunability from 2.42 GHz to 2.66 GHz and 1.3 dB gain drop when using overlapping metallic plates instead of continuous ground plane. The total antenna thickness is approximately lambda/24.

Dielectric Covered Planar Antennas

NASA Technical Reports Server (NTRS)

Llombart Juan, Nuria (Inventor); Lee, Choonsup (Inventor); Chattopadhyay, Goutam (Inventor); Gill, John J. (Inventor); Skalare, Anders J. (Inventor); Siegel, Peter H. (Inventor)

2014-01-01

An antenna element suitable for integrated arrays at terahertz frequencies is disclosed. The antenna element comprises an extended spherical (e.g. hemispherical) semiconductor lens, e.g. silicon, antenna fed by a leaky wave waveguide feed. The extended spherical lens comprises a substantially spherical lens adjacent a substantially planar lens extension. A couple of TE/TM leaky wave modes are excited in a resonant cavity formed between a ground plane and the substantially planar lens extension by a waveguide block coupled to the ground plane. Due to these modes, the primary feed radiates inside the lens with a directive pattern that illuminates a small sector of the lens. The antenna structure is compatible with known semiconductor fabrication technology and enables production of large format imaging arrays.

Broad band antennas and feed methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benzel, David M.; Twogood, Richard E.

Two or more Vivaldi antennas, consisting of two plates each, each with the antenna's natural impedance of approximately 100 ohms, are placed in parallel to achieve a 50 ohm impedance in the case of two antennas or other impedances (100/n ohms) for more than two antennas. A single Vivaldi antenna plate (half Vivaldi antenna) over a ground plane can also be used to achieve a 50 ohm impedance, or two or more single plates over a ground plane to achieve other impedances. Unbalanced 50 ohm transmission lines, e.g. coaxial cables, can be used to directly feed, the dual Vivaldi (fourmore » plate) antenna in a center fed angled center departure, or more desirably, a center fed offset departure configuration.« less

A study of surface and subsurface ground motions at Calico Hills, Nevada Test Site

USGS Publications Warehouse

King, Kenneth W.

1982-01-01

A study of earthquake ground motions recorded at depth in a drill hole and at the ground surface has derived the surface to subsurface transfer functions such as might be expected at a potential nuclear waste repository in a similar setting. The site under investigation has small seismic velocity contrasts in the layers of rock between the surface and the subsurface seismometer location. The subsurface seismic motions were similar in spectral characteristics to the surface motions and were lower in amplitude across the recorded band-width by a factor of 1.5.

Phosphor-free nanopyramid white light-emitting diodes grown on (101{sup ¯}1) planes using nanospherical-lens photolithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Kui; Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology/State Key Lab on Integrated Optoelectronics, Tsinghua University, Beijing 100084; Wei, Tongbo, E-mail: tbwei@semi.ac.cn

2013-12-09

We reported a high-efficiency and low-cost nano-pattern method, the nanospherical-lens photolithography technique, to fabricate a SiO{sub 2} mask for selective area growth. By controlling the selective growth, we got a highly ordered hexagonal nanopyramid light emitting diodes with InGaN/GaN quantum wells grown on nanofacets, demonstrating an electrically driven phosphor-free white light emission. We found that both the quantum well width and indium incorporation increased linearly along the (101{sup ¯}1) planes towards the substrate and the perpendicular direction to the (101{sup ¯}1) planes as well. Such spatial distribution was responsible for the broadband emission. Moreover, using cathodoluminescence techniques, it was foundmore » that the blue emission originated from nanopyramid top, resembling the quantum dots, green emission from the InGaN quantum wells layer at the middle of sidewalls, and yellow emission mainly from the bottom of nanopyramid ridges, similar to the quantum wires.« less

The nature of pulsar radio emission

NASA Astrophysics Data System (ADS)

Dyks, J.; Rudak, B.; Demorest, P.

2010-01-01

High-quality averaged radio profiles of some pulsars exhibit double, highly symmetric features both in emission and in absorption. It is shown that both types of feature are produced by a split fan beam of extraordinary-mode curvature radiation that is emitted/absorbed by radially extended streams of magnetospheric plasma. With no emissivity in the plane of the stream, such a beam produces bifurcated emission components (BFCs) when our line of sight passes through the plane. An example of a double component created in this way is present in the averaged profile of the 5-ms pulsar J1012+5307. We show that the component can indeed be very well fitted by the textbook formula for the non-coherent beam of curvature radiation in the polarization state that is orthogonal to the plane of electron trajectory. The observed width of the BFC decreases with increasing frequency at a rate that confirms the curvature origin. Likewise, the double absorption features (double notches) are produced by the same beam of the extraordinary-mode curvature radiation, when it is eclipsed by thin plasma streams. The intrinsic property of curvature radiation to create bifurcated fan beams explains the double features in terms of a very natural geometry and implies the curvature origin of pulsar radio emission. Similarly, the `double conal' profiles of class D result from a cut through a wider stream with finite extent in magnetic azimuth. Therefore, their width reacts very slowly to changes of viewing geometry resulting from geodetic precession. The stream-cut interpretation implies a highly non-orthodox origin of both the famous S-swing of polarization angle and the low-frequency pulse broadening in D profiles. The azimuthal structure of polarization modes in the curvature radiation beam provides an explanation for the polarized `multiple imaging' and the edge depolarization of pulsar profiles.

Age-related differences in the maintenance of frontal plane dynamic stability while stepping to targets

PubMed Central

Hurt, Christopher P.; Grabiner, Mark D.

2015-01-01

Older adults may be vulnerable to frontal plane dynamic instability, which is of clinical significance. The purpose of the current investigation was to examine the age-related differences in frontal plane dynamic stability by quantifying the margin of stability and hip abductor moment generation of subjects performing a single crossover step and sidestep to targets that created three different step widths during forward locomotion. Nineteen young adults (9 males, age: 22.9±3.1 years, height: 174.3±10.2 cm, mass: 71.7±13.0 kg) and 18 older adults (9 males, age: 72.8±5.2 years, height: 174.9±8.6 cm, mass: 78.0±16.3 kg) participated. For each walking trial, subjects performed a single laterally-directed step to a target on a force plate. Subjects were instructed to “perform the lateral step and keep walking forward”. The peak hip abductor moment of the stepping limb was 42% larger by older adults compared to younger adults (p<0.001). Older adults were also more stable than younger adults at all step targets (p<0.001). Older adults executed the lateral step with slower forward-directed and lateral-directed velocity despite similar step widths. Age-related differences in hip abduction moments may reflect greater muscular effort by older adults to reduce the likelihood of becoming unstable. The results of this investigation, in which subjects performed progressively larger lateral-directed steps, provide evidence that older adults may not be more laterally unstable than younger adults. However, age-related differences in this study could also reflect a compensatory strategy by older adults to ensure stability while performing this task. PMID:25627870

Age-related differences in the maintenance of frontal plane dynamic stability while stepping to targets.

PubMed

Hurt, Christopher P; Grabiner, Mark D

2015-02-26

Older adults may be vulnerable to frontal plane dynamic instability, which is of clinical significance. The purpose of the current investigation was to examine the age-related differences in frontal plane dynamic stability by quantifying the margin of stability and hip abductor moment generation of subjects performing a single crossover step and sidestep to targets that created three different step widths during forward locomotion. Nineteen young adults (9 males, age: 22.9±3.1 years, height: 174.3±10.2cm, mass: 71.7±13.0kg) and 18 older adults (9 males, age: 72.8±5.2 years, height: 174.9±8.6cm, mass: 78.0±16.3kg) participated. For each walking trial, subjects performed a single laterally-directed step to a target on a force plate. Subjects were instructed to "perform the lateral step and keep walking forward". The peak hip abductor moment of the stepping limb was 42% larger by older adults compared to younger adults (p<0.001). Older adults were also more stable than younger adults at all step targets (p<0.001). Older adults executed the lateral step with slower forward-directed and lateral-directed velocity despite similar step widths. Age-related differences in hip abduction moments may reflect greater muscular effort by older adults to reduce the likelihood of becoming unstable. The results of this investigation, in which subjects performed progressively larger lateral-directed steps, provide evidence that older adults may not be more laterally unstable than younger adults. However, age-related differences in this study could also reflect a compensatory strategy by older adults to ensure stability while performing this task. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of implant angulation, impression material, and variation in arch curvature width on implant transfer model accuracy.

PubMed

Akalin, Zerrin Fidan; Ozkan, Yasemin Kulak; Ekerim, Ahmet

2013-01-01

The effects of implant angulation, impression material, and variation in width of the arch curvature on transfer models were evaluated. Three edentulous maxillary epoxy resin models were fabricated, and six internal-connection implant analogs were placed in different locations and different angulations in each model. In the first model, implants were positioned in the canine, first premolar, and first molar regions, and all analogs were positioned parallel to each other and perpendicular to the horizontal crestal plane (parallel model). In the second model, analogs were positioned in same regions (canine, first premolar, and first molar), but three of them were positioned with 10-degree buccal angulations (versus the horizontal crestal plane) (angular model). In the third model, analogs were inserted in the lateral incisor, canine, and second molar regions and parallel to each other (wide-arch model). Eighteen impressions of each model were made with each of the three materials--condensation silicone, polyvinyl siloxane, and polyether--and impressions were poured and kept at room temperature for 24 hours. They were then observed under a toolmaker's microscope, with epoxy resin models of each group used as references. Distance deformations between implants in each model in the x- and y-axes were recorded separately. Implant angulation deformations were recorded in the x-z plane. Statistical evaluations were performed with analysis of variance and the least significant difference post hoc test. Angular model measurements showed the greatest deformation values (P < .05). All impression materials showed deformation, and the polyether impression models showed statistically significantly less deformation in angular measurements (P < .05). The models with implants placed parallel to each other exhibited greater accuracy than a model with implants placed at angles to each other.

Hibernating black holes revealed by photometric mass functions

NASA Astrophysics Data System (ADS)

Casares, Jorge

2018-02-01

We present a novel strategy to uncover the Galactic population of quiescent black holes (BHs). This is based on a new concept, the photometric mass function (PMF), which opens up the possibility of an efficient identification of dynamical BHs in large fields-of-view. This exploits the width of the disc H α emission line, combined with orbital period information. We here show that H α widths can be recovered using a combination of customized H α filters. By setting a width cut-off at 2200 km s-1 we are able to cleanly remove other Galactic populations of H α emitters, including ∼99.9 per cent of cataclysmic variables (CVs). Only short-period (Porb <2.1 h) eclipsing CVs and AGNs will contaminate the sample but these can be easily flagged through photometric variability and, in the latter case, also mid-IR colours. We also describe the strategy of a deep (r = 22) Galactic plane survey based on the concept of PMFs: HAWKs, the HAlpha-Width Kilo-deg Survey. We estimate that ∼800 deg2 are required to unveil ∼50 new dynamical BHs, a three-fold improvement over the known population. For comparison, a century would be needed to produce an enlarged sample of 50 dynamical BHs from X-ray transients at the current discovery rate.

Tooth display and lip position during spontaneous and posed smiling in adults.

PubMed

Van Der Geld, Pieter; Oosterveld, Paul; Berge, Stefaan J; Kuijpers-Jagtman, Anne M

2008-08-01

To analyze differences in tooth display, lip-line height, and smile width between the posed smiling record, traditionally produced for orthodontic diagnosis, and the spontaneous (Duchenne) smile of joy. The faces of 122 male participants were each filmed during spontaneous and posed smiling. Spontaneous smiles were elicited through the participants watching a comical movie. Maxillary and mandibular lip-line heights, tooth display, and smile width were measured using a digital videographic method for smile analysis. Paired sample t-tests were used to compare measurements of posed and spontaneous smiling. Maxillary lip-line heights during spontaneous smiling were significantly higher than during posed smiling. Compared to spontaneous smiling, tooth display in the (pre)molar area during posed smiling decreased by up to 30%, along with a significant reduction of smile width. During posed smiling, also mandibular lip-line heights changed and the teeth were more covered by the lower lip than during spontaneous smiling. Reduced lip-line heights, tooth display, and smile width on a posed smiling record can have implications for the diagnostics of lip-line height, smile arc, buccal corridors, and plane of occlusion. Spontaneous smiling records next to posed smiling records are therefore recommended for diagnostic purposes. Because of the dynamic nature of spontaneous smiling, it is proposed to switch to dynamic video recording of the smile.

Complete band gaps of phononic crystal plates with square rods.

PubMed

El-Naggar, Sahar A; Mostafa, Samia I; Rafat, Nadia H

2012-04-01

Much of previous work has been devoted in studying complete band gaps for bulk phononic crystal (PC). In this paper, we theoretically investigate the existence and widths of these gaps for PC plates. We focus our attention on steel rods of square cross sectional area embedded in epoxy matrix. The equations for calculating the dispersion relation for square rods in a square or a triangular lattice have been derived. Our analysis is based on super cell plane wave expansion (SC-PWE) method. The influence of inclusions filling factor and plate thickness on the existence and width of the phononic band gaps has been discussed. Our calculations show that there is a certain filling factor (f=0.55) below which arrangement of square rods in a triangular lattice is superior to the arrangement in a square lattice. A comparison between square and circular cross sectional rods reveals that the former has superior normalized gap width than the latter in case of a square lattice. This situation is switched in case of a triangular lattice. Moreover, a maximum normalized gap width of 0.7 can be achieved for PC plate of square rods embedded in a square lattice and having height 90% of the lattice constant. Copyright © 2011 Elsevier B.V. All rights reserved.

Fano resonances of a ring-shaped "hexamer" cluster at near-infrared wavelength

NASA Astrophysics Data System (ADS)

Liu, Tong-Tong; Xia, Feng; Sun, Peng; Liu, Li-Li; Du, Wei; Li, Meng-Xue; Kong, Wei-Jin; Wan, Yong; Dong, Li-Feng; Yun, Mao-Jin

2018-03-01

Fano resonances have been studied intensely in the last decade, since it is an important way to decrease the resonance line width and enhance local electric field. However, achieving a Fano line-shape with both narrow line width and high spectral contrast ratio is still a challenge. In this paper, we theoretically predict the Fano resonance induced by the extinction of normal plane wave in a ring-shaped hexamer cluster at near-infrared wavelength. In order to obtain the narrow Fano line width and high spectral contrast ratio, the relationships between the Fano line-shape and the parameters of the nanostructure are analyzed in detail. The nanostructure is simulated by using commercial software based on finite element method. The simulation results show that when the structural parameters are optimized, the Fano line width can be narrowed down 0.028 eV with a contrast ratio of 86%, and the local electric field enhancement factor at the Fano resonance wavelength can reach to 36. Furthermore, the effective mode volume of the structure is 3.9 ×10-23m3 which is lower than the available literature. These results indicate many potential applications of the Fano resonance in multiwavelength surface-enhanced Raman scattering and biosensing.

In-Plane Angular Effect of Magnetoresistance of Quasi-One-Dimensional Organic Metals, (DMET) 2AuBr 2 and (TMTSF) 2ClO 4

NASA Astrophysics Data System (ADS)

Yoshino, Harukazu; Saito, Kazuya; Nishikawa, Hiroyuki; Kikuchi, Koichi; Kobayashi, Keiji; Ikemoto, Isao

1997-08-01

Comparative study is presented for the in-plane angular effect of magnetoresistance of quasi-one-dimensional organic conductors, (DMET)2AuBr2 and (TMTSF)2ClO4. The magnetoresistance for the magnetic and electrical fields parallel and perpendicular to the most conducting plane, respectively, was measured at 4.2 K and up to 7.0 T. (DMET)2AuBr2 shows an anomalous hump in the field-orientation dependence of the magnetoresistance for the magnetic field nearly parallel to the most conducting axis and this is very similar to what previously reported for (DMET)2I3. Weak anomaly was detected for the magnetoresistance of (TMTSF)2ClO4 in the Relaxed state, while no anomaly was observed in the SDW phase in the Quenched state. By comparing the numerical angular derivatives of the magnetoresistance, it is shown that the anomaly in the in-plane angular effect continuously develops from zero magnetic field and is closely related to the quasi-one-dimensional Fermi surface. A simple method is proposed to estimate the anisotropy of the transfer integral from the width of the hump anomaly.

Modified femtosecond laser inscription method for tailored grating sensors in encapsulated silica and low-loss polymer optical fibres

NASA Astrophysics Data System (ADS)

Kalli, Kyriacos; Lacraz, Amedee; Theodosiou, Andreas; Kofinas, Marios

2016-05-01

There is great interest in the development of flexible wavelength filters and optical fibre sensors, such as Bragg and superstructure gratings, grating arrays and chirped gratings in glass and polymer optical fibres. A major hurdle is the development of an inscription method that should offer flexibility and reliability and be generally applicable to all optical fibre types. With this in mind we have developed a novel femtosecond laser inscription method; plane-by-plane inscription, whereby a 3D-index change of controlled length across the fibre core, width along the fibre axis and depth is written into the optical fibre. We apply this method for the inscription of various grating types in coated silica and low- loss CYTOP polymer optical fibres. The plane-by-plane method allows for multiple and overlapping gratings in the fibre core. Moreover, we demonstrate that this novel fibre Bragg grating inscription technique can be used to modify and add versatility to an existing, encapsulated optical fibre pressure sensor. The femtosecond laser is operated in the green or the near infra-red, based on the material properties under laser modification.

Ground-state properties of H 5 from the He 6 ( d , He 3 ) H 5 reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wuosmaa, A. H.; Bedoor, S.; Brown, K. W.

2017-01-01

We have studied the ground state of the unbound, very neutron-rich isotope of hydrogen 5H, using the 6He(d,3He)5H reaction in inverse kinematics at a bombarding energy of E(6He)=55A MeV. The present results suggest a ground-state resonance energy ER=2.4±0.3 MeV above the 3H+2n threshold, with an intrinsic width of Γ=5.3±0.4 MeV in the 5H system. Both the resonance energy and width are higher than those reported in some, but not all previous studies of 5H. The previously unreported 6He(d,t)5Heg.s. reaction is observed in the same measurement, providing a check on the understanding of the response of the apparatus. The data aremore » compared to expectations from direct two-neutron and dineutron decay. The possibility of excited states of 5H populated in this reaction is discussed using different calculations of the 6He→5H+p spectroscopic overlaps from shell-model and ab initio nuclear-structure calculations.« less

SIELETERS: A Static Fourier Transform Infrared Imaging Spectrometer for Airborne Hyperspectral Measurements

DTIC Science & Technology

2009-10-01

cryostat and cooled at a temperature under 77K by a Stirling cryocooler , as represented on the following Figure 5 : Cryostat...Figure 5. Detector cryostat and cryocooler The read-out frequency of the detectors is adapted to the ground speed of the plane above...Cold shield Detector plane Cryocoole r Cryocoole r compresso r Fixed frame Roll frame Pitch frame Yaw frame SIELETERS: a Static Fourier

The airglow layer emission altitude cannot be determined unambiguously from temperature comparison with lidars

NASA Astrophysics Data System (ADS)

Dunker, Tim

2018-05-01

I investigate the nightly mean emission height and width of the OH* (3-1) layer by comparing nightly mean temperatures measured by the ground-based spectrometer GRIPS 9 and the Na lidar at ALOMAR. The data set contains 42 coincident measurements taken between November 2010 and February 2014, when GRIPS 9 was in operation at the ALOMAR observatory (69.3° N, 16.0° E) in northern Norway. To closely resemble the mean temperature measured by GRIPS 9, I weight each nightly mean temperature profile measured by the lidar using Gaussian distributions with 40 different centre altitudes and 40 different full widths at half maximum. In principle, one can thus determine the altitude and width of an airglow layer by finding the minimum temperature difference between the two instruments. On most nights, several combinations of centre altitude and width yield a temperature difference of ±2 K. The generally assumed altitude of 87 km and width of 8 km is never an unambiguous, good solution for any of the measurements. Even for a fixed width of ˜ 8.4 km, one can sometimes find several centre altitudes that yield equally good temperature agreement. Weighted temperatures measured by lidar are not suitable to unambiguously determine the emission height and width of an airglow layer. However, when actual altitude and width data are lacking, a comparison with lidars can provide an estimate of how representative a measured rotational temperature is of an assumed altitude and width. I found the rotational temperature to represent the temperature at the commonly assumed altitude of 87.4 km and width of 8.4 km to within ±16 K, on average. This is not a measurement uncertainty.

Comparison of ATLOG and Xyce for Bell Labs Electromagnetic Pulse Excitation of Finite-Long Dissipative Conductors over a Ground Plane.

DOE Office of Scientific and Technical Information (OSTI.GOV)

campione, Salvatore; Warne, Larry K.; Schiek, Richard

This report details the modeling results for the response of a finite-length dissipative conductor interacting with a conducting ground to the Bell Labs electromagnetic pulse excitation. We use both a frequency-domain and a time-domain method based on transmission line theory through a code we call ATLOG - Analytic Transmission Line Over Ground. Results are compared to the circuit simulator Xyce for selected cases. Intentionally Left Blank

Electromagnetic Pulse Excitation of Finite-Long Dissipative Conductors over a Conducting Ground Plane in the Frequency Domain.

DOE Office of Scientific and Technical Information (OSTI.GOV)

campione, Salvatore; Warne, Larry K.; Schiek, Richard

2017-09-01

This report details the modeling results for the response of a finite-length dissipative conductor interacting with a conducting ground to a hypothetical nuclear device with the same output energy spectrum as the Fat Man device. We use a frequency-domain method based on transmission line theory and implemented it in a code we call ATLOG - Analytic Transmission Line Over Ground. Select results are compared to ones computed using the circuit simulator Xyce. Intentionally Left Blank

Fabrication of a Cryogenic Bias Filter for Ultrasensitive Focal Plane

NASA Technical Reports Server (NTRS)

Chervenak, James; Wollack, Edward

2012-01-01

A fabrication process has been developed for cryogenic in-line filtering for the bias and readout of ultrasensitive cryogenic bolometers for millimeter and submillimeter wavelengths. The design is a microstripline filter that cuts out, or strongly attenuates, frequencies (10 50 GHz) that can be carried by wiring staged at cryogenic temperatures. The filter must have 100-percent transmission at DC and low frequencies where the bias and readout lines will carry signal. The fabrication requires the encapsulation of superconducting wiring in a dielectric-metal envelope with precise electrical characteristics. Sufficiently thick insulation layers with high-conductivity metal layers fully surrounding a patterned superconducting wire in arrayable formats have been demonstrated. A degenerately doped silicon wafer has been chosen to provide a metallic ground plane. A metallic seed layer is patterned to enable attachment to the ground plane. Thick silicon dioxide films are deposited at low temperatures to provide tunable dielectric isolation without degrading the metallic seed layer. Superconducting wiring is deposited and patterned using microstripline filtering techniques to cut out the relevant frequencies. A low Tc superconductor is used so that it will attenuate power strongly above the gap frequency. Thick dielectric is deposited on top of the circuit, and then vias are patterned through both dielectric layers. A thick conductive film is deposited conformally over the entire circuit, except for the contact pads for the signal and bias attachments to complete the encapsulating ground plane. Filters are high-aspect- ratio rectangles, allowing close packing in one direction, while enabling the chip to feed through the wall of a copper enclosure. The chip is secured in the copper wall using a soft metal seal to make good thermal and electrical contact to the outer shield.

Tool Indicates Contact Angles In Bearing Raceways

NASA Technical Reports Server (NTRS)

Akian, Richard A.; Butner, Myles F.

1995-01-01

Tool devised for use in measuring contact angles between balls and races in previously operated ball bearings. Used on both inner and outer raceways of bearings having cross-sectional widths between approximately 0.5 and 2.0 in. Consists of integral protractor mounted in vertical plane on bracket equipped with leveling screws and circular level indicator. Protractor includes rotatable indicator needle and set of disks of various sizes to fit various raceway curvatures.

Quantum Optics Initiative

DTIC Science & Technology

2007-06-30

the choice for the specificity parameter (S), which is the area around the 51(±3) cm 1 frequency in the Fourier plane (right in Fig...1). The HOMO is believed to be entirely of phthalocyanine character in Alu symmetry of the D4h group [6]. The full-width-at- half - maximum (FWHM) of...quantum Lyapunov exponents or by examining the corresponding Poincare sections in this limit. Since the Bohmian formulation of quantum theory is based

Hierarchical sinuous-antenna phased array for millimeter wavelengths

NASA Astrophysics Data System (ADS)

Cukierman, Ari; Lee, Adrian T.; Raum, Christopher; Suzuki, Aritoki; Westbrook, Benjamin

2018-03-01

We present the design, fabrication, and measured performance of a hierarchical sinuous-antenna phased array coupled to superconducting transition-edge-sensor (TES) bolometers for millimeter wavelengths. The architecture allows for dual-polarization wideband sensitivity with a beam width that is approximately frequency-independent. We report on measurements of a prototype device, which uses three levels of triangular phased arrays to synthesize beams that are approximately constant in width across three frequency bands covering a 3:1 bandwidth. The array element is a lens-coupled sinuous antenna. The device consists of an array of hemispherical lenses coupled to a lithographed wafer, which integrates TESs, planar sinuous antennas, and microwave circuitry including band-defining filters. The approximately frequency-independent beam widths improve coupling to telescope optics and keep the sensitivity of an experiment close to optimal across a broad frequency range. The design can be straightforwardly modified for use with non-TES lithographed cryogenic detectors such as kinetic inductance detectors. Additionally, we report on the design and measurements of a broadband 180° hybrid that can simplify the design of future multichroic focal planes including but not limited to hierarchical phased arrays.

Experimental and theoretical investigation of the rocking curves measured for Mo K α X-ray characteristic lines in the double-crystal nondispersive scheme

NASA Astrophysics Data System (ADS)

Marchenkov, N. V.; Chukhovskii, F. N.; Blagov, A. E.

2015-03-01

The rocking curves (RCs) for Mo K α1 h Mo K α2 characteristic X-ray lines have been experimentally and theoretically studied in the nondispersive scheme of an X-ray double-crystal TPC-K diffractometer. The results of measurements and theoretical calculations of double-crystal RCs for characteristic X-rays from tubes with a molybdenum anode and different widths of slits show that a decrease in the slit width leads to an increase in the relative contribution of the Mo K α2-line RC in comparison with the intensity of the tails of the Mo K α1-line RC. It is shown that the second peak of the Mo K α2 line becomes increasingly pronounced in the tail of the Mo K α1-line RC with a decrease in the slit width. Two plane-parallel Si plates (input faces {110}, diffraction vector h <220>) were used as a monochromator crystal and a sample. The results of measuring double-crystal RCs are in good agreement with theoretical calculations.

Equivalence of linear canonical transform domains to fractional Fourier domains and the bicanonical width product: a generalization of the space-bandwidth product.

PubMed

Oktem, Figen S; Ozaktas, Haldun M

2010-08-01

Linear canonical transforms (LCTs) form a three-parameter family of integral transforms with wide application in optics. We show that LCT domains correspond to scaled fractional Fourier domains and thus to scaled oblique axes in the space-frequency plane. This allows LCT domains to be labeled and ordered by the corresponding fractional order parameter and provides insight into the evolution of light through an optical system modeled by LCTs. If a set of signals is highly confined to finite intervals in two arbitrary LCT domains, the space-frequency (phase space) support is a parallelogram. The number of degrees of freedom of this set of signals is given by the area of this parallelogram, which is equal to the bicanonical width product but usually smaller than the conventional space-bandwidth product. The bicanonical width product, which is a generalization of the space-bandwidth product, can provide a tighter measure of the actual number of degrees of freedom, and allows us to represent and process signals with fewer samples.

Simultaneous effects of temperature and pressure on the donor binding energy in a V-groove quantum wire

NASA Astrophysics Data System (ADS)

Khordad, R.

2010-03-01

The influence of temperature and pressure, simultaneously, on the binding energy of a hydrogenic donor impurity in a ridge GaAs/Ga 1- xAl xAs quantum wire is studied using a variational procedure within the effective mass approximation. The subband energy and the binding energy of the donor impurity in its ground state as a function of the wire bend width and impurity location at different temperatures and pressures are calculated. The results show that, when the temperature increases, the donor binding energy decreases for a constant applied pressure for all wire bend widths. Also, the binding energy increases by increasing the pressure for a constant temperature for all wire bend widths. In addition, when the temperature and pressure are applied simultaneously the binding energy decreases as the quantum wire bend width increases. On the whole, it is deduced that the temperature and pressure have important effects on the donor binding energy in a V-groove quantum wire.

Detection of Coal Fires: A Case Study Conducted on Indian Coal Seams Using Neural Network and Particle Swarm Optimization

NASA Astrophysics Data System (ADS)

Singh, B. B.

2016-12-01

India produces majority of its electricity from coal but a huge quantity of coal burns every day due to coal fires and also poses a threat to the environment as severe pollutants. In the present study we had demonstrated the usage of Neural Network based approach with an integrated Particle Swarm Optimization (PSO) inversion technique. The Self Potential (SP) data set is used for the early detection of coal fires. The study was conducted over the East Basuria colliery, Jharia Coal Field, Jharkhand, India. The causative source was modelled as an inclined sheet like anomaly and the synthetic data was generated. Neural Network scheme consists of an input layer, hidden layers and an output layer. The input layer corresponds to the SP data and the output layer is the estimated depth of the coal fire. A synthetic dataset was modelled with some of the known parameters such as depth, conductivity, inclination angle, half width etc. associated with causative body and gives a very low misfit error of 0.0032%. Therefore, the method was found accurate in predicting the depth of the source body. The technique was applied to the real data set and the model was trained until a very good correlation of determination `R2' value of 0.98 is obtained. The depth of the source body was found to be 12.34m with a misfit error percentage of 0.242%. The inversion results were compared with the lithologs obtained from a nearby well which corresponds to the L3 coal seam. The depth of the coal fire had exactly matched with the half width of the anomaly which suggests that the fire is widely spread. The inclination angle of the anomaly was 135.510 which resembles the development of the geometrically complex fracture planes. These fractures may be developed due to anisotropic weakness of the ground which acts as passage for the air. As a result coal fires spreads along these fracture planes. The results obtained from the Neural Network was compared with PSO inversion results and were found in complete agreement. PSO technique had already been found a well-established technique to model SP anomalies. Therefore for successful control and mitigation, SP surveys coupled with Neural Network and PSO technique proves to be novel and economical approach along with other existing geophysical techniques. Keywords: PSO, Coal fire, Self-Potential, Inversion, Neural Network

Investigation of a L1-optimized choke ring ground plane for a low-cost GPS receiver-system

NASA Astrophysics Data System (ADS)

Zhang, Li; Schwieger, Volker

2018-01-01

Besides the geodetic dual-frequency GNSS receivers-systems (receiver and antenna), there are also low-cost single-frequency GPS receiver-systems. The multipath effect is a limiting factor of accuracy for both geodetic dual-frequency and low-cost single-frequency GPS receivers. And the multipath effect is for the short baselines dominating error (typical for the monitoring in Engineering Geodesy). So accuracy and reliability of GPS measurement for monitoring can be improved by reducing the multipath signal. In this paper, the self-constructed L1-optimized choke ring ground plane (CR-GP) is applied to reduce the multipath signal. Its design will be described and its performance will be investigated. The results show that the introduced low-cost single-frequency GPS receiver-system, which contains the Ublox LEA-6T single-frequency GPS receiver and Trimble Bullet III antenna with a self-constructed L1-optimized CR-GP, can reach standard deviations of 3 mm in east, 5 mm in north and 9 mm in height in the test field which has many reflectors. This accuracy is comparable with the geodetic dual-frequency GNSS receiver-system. The improvement of the standard deviation of the measurement using the CR-GP is about 50 % and 35 % compared to the used antenna without shielding and with flat ground plane respectively.

Ground Effect - Theory and Practice

NASA Technical Reports Server (NTRS)

Pistolesi, E

1937-01-01

The conclusion of a previous article by Pistolesi is that the increment of lift due to ground effect is largely attributable to the effect of induction of the free vortices, and is practically equivalent to a virtual increase in aspect ratio. The ground clearance was of the order of magnitude comparable to the wing chord. New reports by Le Seur and Datwyler treat the case of minimum distance from the ground and is confined to the plane problem only. The author briefly reviews these reports and also one by Timotika. References to all the reviewed reports are in the attached bibliography.

VIEW OF CONTROL PANEL (RIGHT) AT THE GROUND FLOOR LEVEL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF CONTROL PANEL (RIGHT) AT THE GROUND FLOOR LEVEL AND SIDE OF THE MISSILE TUBE (FOREGROUND). VIEW FACING EAST - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

DETAIL OF INTERIOR OF MISSILE TUBE AT GROUND FLOOR LEVEL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL OF INTERIOR OF MISSILE TUBE AT GROUND FLOOR LEVEL SHOWING AIR COMPRESSOR TANKS AND CURVING STEEL PIECE. VIEW FACING EAST - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

Accelerated Time-Domain Modeling of Electromagnetic Pulse Excitation of Finite-Length Dissipative Conductors over a Ground Plane via Function Fitting and Recursive Convolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campione, Salvatore; Warne, Larry K.; Sainath, Kamalesh

In this report we overview the fundamental concepts for a pair of techniques which together greatly hasten computational predictions of electromagnetic pulse (EMP) excitation of finite-length dissipative conductors over a ground plane. In a time- domain, transmission line (TL) model implementation, predictions are computationally bottlenecked time-wise, either for late-time predictions (about 100ns-10000ns range) or predictions concerning EMP excitation of long TLs (order of kilometers or more ). This is because the method requires a temporal convolution to account for the losses in the ground. Addressing this to facilitate practical simulation of EMP excitation of TLs, we first apply a techniquemore » to extract an (approximate) complex exponential function basis-fit to the ground/Earth's impedance function, followed by incorporating this into a recursion-based convolution acceleration technique. Because the recursion-based method only requires the evaluation of the most recent voltage history data (versus the entire history in a "brute-force" convolution evaluation), we achieve necessary time speed- ups across a variety of TL/Earth geometry/material scenarios. Intentionally Left Blank« less

Analysis of Ninety Degree Flexure Tests for Characterization of Composite Transverse Tensile Strength

NASA Technical Reports Server (NTRS)

OBrien, T. Kevin; Krueger, Ronald

2001-01-01

Finite element (FE) analysis was performed on 3-point and 4-point bending test configurations of ninety degree oriented glass-epoxy and graphite-epoxy composite beams to identify deviations from beam theory predictions. Both linear and geometric non-linear analyses were performed using the ABAQUS finite element code. The 3-point and 4-point bending specimens were first modeled with two-dimensional elements. Three-dimensional finite element models were then performed for selected 4-point bending configurations to study the stress distribution across the width of the specimens and compare the results to the stresses computed from two-dimensional plane strain and plane stress analyses and the stresses from beam theory. Stresses for all configurations were analyzed at load levels corresponding to the measured transverse tensile strength of the material.

Strained-layer superlattice focal plane array having a planar structure

DOEpatents

Kim, Jin K [Albuquerque, NM; Carroll, Malcolm S [Albuquerque, NM; Gin, Aaron [Albuquerque, NM; Marsh, Phillip F [Lowell, MA; Young, Erik W [Albuquerque, NM; Cich, Michael J [Albuquerque, NM

2010-07-13

An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

Strained layer superlattice focal plane array having a planar structure

DOEpatents

Kim, Jin K; Carroll, Malcolm S; Gin, Aaron; Marsh, Phillip F; Young, Erik W; Cich, Michael J

2012-10-23

An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

Stand-off transmission lines and method for making same

DOEpatents

Tuckerman, David B.

1991-01-01

Standoff transmission lines in an integrated circuit structure are formed by etching away or removing the portion of the dielectric layer separating the microstrip metal lines and the ground plane from the regions that are not under the lines. The microstrip lines can be fabricated by a subtractive process of etching a metal layer, an additive process of direct laser writing fine lines followed by plating up the lines or a subtractive/additive process in which a trench is etched over a nucleation layer and the wire is electrolytically deposited. Microstrip lines supported on freestanding posts of dielectric material surrounded by air gaps are produced. The average dielectric constant between the lines and ground plane is reduced, resulting in higher characteristic impedance, less crosstalk between lines, increased signal propagation velocities, and reduced wafer stress.

Analysis of three-dimensional-cavity-backed aperture antennas using a Combined Finite Element Method/Method of Moments/Geometrical Theory of Diffraction technique

NASA Technical Reports Server (NTRS)

Reddy, C. J.; Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.

1995-01-01

A combined finite element method (FEM) and method of moments (MoM) technique is presented to analyze the radiation characteristics of a cavity-fed aperture in three dimensions. Generalized feed modeling has been done using the modal expansion of fields in the feed structure. Numerical results for some feeding structures such as a rectangular waveguide, circular waveguide, and coaxial line are presented. The method also uses the geometrical theory of diffraction (GTD) to predict the effect of a finite ground plane on radiation characteristics. Input admittance calculations for open radiating structures such as a rectangular waveguide, a circular waveguide, and a coaxial line are shown. Numerical data for a coaxial-fed cavity with finite ground plane are verified with experimental data.

Space shuttle: Longitudinal aerodynamic characteristics of low aspect ratio wing configurations in ground effect for a moving and stationary ground surface

NASA Technical Reports Server (NTRS)

Romere, P. O.; Chambliss, E. B.

1972-01-01

A 0.05-scale model of the NASA-MSC Orbiter 040A Configuration was tested. Test duration was approximately 80 hours during which the model was tested in and out of ground effect with a stationary and moving ground belt. Model height from ground plane surface was varied from one and one-half wing span to landing touchdown while angle of attack varied from -4 to 20 degrees. Eleven effectiveness and alternate configuration geometries were tested to insure complete analysis of low aspect ratio wing aircraft in the presence of ground effect. Test Mach number was approximately 0.067 with a corresponding dynamic pressure value of 6.5 psf.

The Homo sapiens 'hemibun': its developmental pattern and the problem of homology.

PubMed

Nowaczewska, W; Kuźmiński, L

2009-01-01

The occipital bun is widely considered a Neanderthal feature. Its homology to the 'hemibun' observed in some European Upper Palaeolithic anatomically modern humans is a current problem. This study quantitatively evaluates the degree of occipital plane convexity in African and Australian modern human crania to analyse a relationship between this feature and some neurocranial variables. Neanderthal and European Upper Palaeolithic Homo sapiens crania were included in the analysis as well. The results of this study indicated that there is a significant relationship between the degree of occipital plane convexity and the following two features in the examined crania of modern humans: the ratio of the maximum neurocranial height to the maximum width of the vault and the ratio of bregma-lambda chord to bregma-lambda arc. The results also revealed that some H. sapiens crania (modern and fossil) show the Neanderthal shape of the occipital plane and that the neurocranial height and shape of parietal midsagittal profile has an influence on occipital plane convexity in the hominins included in this study. This study suggests that the occurrence of the great convexity of the occipital plane in the Neanderthals and H. sapiens is a "by-product" of the relationship between the same neurocranial features and there is no convincing evidence that the Neanderthal occipital bun and the similar structure in H. sapiens develop during ontogeny in the same way.

Radiological evaluation of the posterior pelvic ring in paediatric patients: Results of a retrospective study developing age- and gender-related non-osseous baseline characteristics in paediatric pelvic computed tomography - References for suspected sacroiliac joint injury.

PubMed

Bayer, Jörg; Neubauer, Jakob; Saueressig, Ulrich; Südkamp, Norbert Paul; Reising, Kilian

2016-04-01

The prevalence of paediatric pelvic injury is low, yet they are often indicative of accompanying injuries, and an instable pelvis at presentation is related to long-term poor outcome. Judging diastasis of the sacroiliac joint in paediatric pelvic computed tomography is challenging, as information on their normal appearance is scarce. We therefore sought to generate age- and gender-related standard width measurements of the sacroiliac joint in children for comparison. A total of 427 pelvic computed tomography scans in paediatric patients (<18 years old) were retrospectively evaluated. After applying exclusion criteria, 350 scans remained for measurements. Taking a standard approach we measured the sacroiliac joint width bilaterally in axial and coronal planes. We illustrate age- and gender-related measurements of the sacroiliac joint width as a designated continuous 3rd, 15th, 50th, 85th and 97th centile graph, respectively. Means and standard deviations in the joint width are reported for four age groups. There are distinct changes in the sacroiliac joint's appearance during growth. In general, male children exhibit broader sacroiliac joints than females at the same age, although this difference is significant only in the 11 to 15-year-old age group. The sacroiliac joint width in children as measured in coronal and axial CT scans differs in association with age and gender. When the sacroiliac joint width is broader than the 97th centile published in our study, we strongly encourage considering a sacroiliac joint injury. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bridge Crack Detection Using Multi-Rotary Uav and Object-Base Image Analysis

NASA Astrophysics Data System (ADS)

Rau, J. Y.; Hsiao, K. W.; Jhan, J. P.; Wang, S. H.; Fang, W. C.; Wang, J. L.

2017-08-01

Bridge is an important infrastructure for human life. Thus, the bridge safety monitoring and maintaining is an important issue to the government. Conventionally, bridge inspection were conducted by human in-situ visual examination. This procedure sometimes require under bridge inspection vehicle or climbing under the bridge personally. Thus, its cost and risk is high as well as labor intensive and time consuming. Particularly, its documentation procedure is subjective without 3D spatial information. In order cope with these challenges, this paper propose the use of a multi-rotary UAV that equipped with a SONY A7r2 high resolution digital camera, 50 mm fixed focus length lens, 135 degrees up-down rotating gimbal. The target bridge contains three spans with a total of 60 meters long, 20 meters width and 8 meters height above the water level. In the end, we took about 10,000 images, but some of them were acquired by hand held method taken on the ground using a pole with 2-8 meters long. Those images were processed by Agisoft PhotoscanPro to obtain exterior and interior orientation parameters. A local coordinate system was defined by using 12 ground control points measured by a total station. After triangulation and camera self-calibration, the RMS of control points is less than 3 cm. A 3D CAD model that describe the bridge surface geometry was manually measured by PhotoscanPro. They were composed of planar polygons and will be used for searching related UAV images. Additionally, a photorealistic 3D model can be produced for 3D visualization. In order to detect cracks on the bridge surface, we utilize object-based image analysis (OBIA) technique to segment the image into objects. Later, we derive several object features, such as density, area/bounding box ratio, length/width ratio, length, etc. Then, we can setup a classification rule set to distinguish cracks. Further, we apply semi-global-matching (SGM) to obtain 3D crack information and based on image scale we can calculate the width of a crack object. For spalling volume calculation, we also apply SGM to obtain dense surface geometry. Assuming the background is a planar surface, we can fit a planar function and convert the surface geometry into a DSM. Thus, for spalling area its height will be lower than the plane and its value will be negative. We can thus apply several image processing technique to segment the spalling area and calculate the spalling volume as well. For bridge inspection and UAV image management within a laboratory, we develop a graphic user interface. The major functions include crack auto-detection using OBIA, crack editing, i.e. delete and add cracks, crack attributing, 3D crack visualization, spalling area/volume calculation, bridge defects documentation, etc.

Broken Plain

NASA Technical Reports Server (NTRS)

2006-01-01

2 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygonally patterned ground on the floor of a trough in the southern hemisphere of Mars. The polygons could be an indicator that ground ice is or was present at this location. The dark streaks were formed by passing dust devils.

Location near: 67.4oS, 240.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

An Atlas of Computed Equivalent Widths of Quasar Broad Emission Lines

NASA Astrophysics Data System (ADS)

Korista, Kirk; Baldwin, Jack; Ferland, Gary; Verner, Dima

We present graphically the results of several thousand photoionization calculations of broad emission-line clouds in quasars, spanning 7 orders of magnitude in hydrogen ionizing flux and particle density. The equivalent widths of 42 quasar emission lines are presented as contours in the particle density-ionizing flux plane for a typical incident continuum shape, solar chemical abundances, and cloud column density of N(H) = 1023 cm-2. Results are similarly given for a small subset of emission lines for two other column densities (1022 and 1024 cm-2), five other incident continuum shapes, and a gas metallicity of 5 Z⊙. These graphs should prove useful in the analysis of quasar emission-line data and in the detailed modeling of quasar broad emission-line regions. The digital results of these emission-line grids and many more are available over the Internet.

Method of fabricating a scalable nanoporous membrane filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tringe, Joseph W; Balhorn, Rodney L; Zaidi, Saleem

A method of fabricating a nanoporous membrane filter having a uniform array of nanopores etch-formed in a thin film structure (e.g. (100)-oriented single crystal silicon) having a predetermined thickness, by (a) using interferometric lithography to create an etch pattern comprising a plurality array of unit patterns having a predetermined width/diameter, (b) using the etch pattern to etch frustum-shaped cavities or pits in the thin film structure such that the dimension of the frustum floors of the cavities are substantially equal to a desired pore size based on the predetermined thickness of the thin film structure and the predetermined width/diameter ofmore » the unit patterns, and (c) removing the frustum floors at a boundary plane of the thin film structure to expose, open, and thereby create the nanopores substantially having the desired pore size.« less

Compression failure mechanisms of single-ply, unidirectional, carbon-fiber composites

NASA Technical Reports Server (NTRS)

Ha, Jong-Bae; Nairn, John A.

1992-01-01

A single-ply composite compression test was used to study compression failure mechanisms as a function of fiber type, matrix type, and interfacial strength. Composites made with low- and intermediate-modulus fibers (Hercules AS4 and IM7) in either an epoxy (Hercules 3501-6) or a thermoplastic (ULTEM and LARC-TPI) matrix failed by kink banding and out-of-plane slip. The failures proceeded by rapid and catastrophic damage propagation across the specimen width. Composites made with high-modulus fibers (Hercules HMS4/3501-6) had a much lower compression strength. Their failures were characterized by kink banding and longitudinal splitting. The damage propagated slowly across the specimen width. Composites made with fibers treated to give low interfacial strength had low compression strength. These composites typically failed near the specimen ends and had long kink bands.

Polygons and Craters

NASA Technical Reports Server (NTRS)

2005-01-01

3 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygons enhanced by subliming seasonal frost in the martian south polar region. Polygons similar to these occur in frozen ground at high latitudes on Earth, suggesting that perhaps their presence on Mars is also a sign that there is or once was ice in the shallow subsurface. The circular features are degraded meteor impact craters.

Location near: 72.2oS, 310.3oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

Image improvement from a sodium-layer laser guide star adaptive optics system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Max, C. E., LLNL

1997-06-01

A sodium-layer laser guide star beacon with high-order adaptive optics at Lick Observatory produced a factor of 2.4 intensity increase and a factor of 2 decrease in full width at half maximum for an astronomical point source, compared with image motion compensation alone. Image full widths at half maximum were identical for laser and natural guide stars (0.3 arc seconds). The Strehl ratio with the laser guide star was 65% of that with a natural guide star. This technique should allow ground-based telescopes to attain the diffraction limit, by correcting for atmospheric distortions.

High-immersion three-dimensional display of the numerical computer model

NASA Astrophysics Data System (ADS)

Xing, Shujun; Yu, Xunbo; Zhao, Tianqi; Cai, Yuanfa; Chen, Duo; Chen, Zhidong; Sang, Xinzhu

2013-08-01

High-immersion three-dimensional (3D) displays making them valuable tools for many applications, such as designing and constructing desired building houses, industrial architecture design, aeronautics, scientific research, entertainment, media advertisement, military areas and so on. However, most technologies provide 3D display in the front of screens which are in parallel with the walls, and the sense of immersion is decreased. To get the right multi-view stereo ground image, cameras' photosensitive surface should be parallax to the public focus plane and the cameras' optical axes should be offset to the center of public focus plane both atvertical direction and horizontal direction. It is very common to use virtual cameras, which is an ideal pinhole camera to display 3D model in computer system. We can use virtual cameras to simulate the shooting method of multi-view ground based stereo image. Here, two virtual shooting methods for ground based high-immersion 3D display are presented. The position of virtual camera is determined by the people's eye position in the real world. When the observer stand in the circumcircle of 3D ground display, offset perspective projection virtual cameras is used. If the observer stands out the circumcircle of 3D ground display, offset perspective projection virtual cameras and the orthogonal projection virtual cameras are adopted. In this paper, we mainly discussed the parameter setting of virtual cameras. The Near Clip Plane parameter setting is the main point in the first method, while the rotation angle of virtual cameras is the main point in the second method. In order to validate the results, we use the D3D and OpenGL to render scenes of different viewpoints and generate a stereoscopic image. A realistic visualization system for 3D models is constructed and demonstrated for viewing horizontally, which provides high-immersion 3D visualization. The displayed 3D scenes are compared with the real objects in the real world.

Efficient Raman sideband cooling of trapped ions to their motional ground state

NASA Astrophysics Data System (ADS)

Che, H.; Deng, K.; Xu, Z. T.; Yuan, W. H.; Zhang, J.; Lu, Z. H.

2017-07-01

Efficient cooling of trapped ions is a prerequisite for various applications of the ions in precision spectroscopy, quantum information, and coherence control. Raman sideband cooling is an effective method to cool the ions to their motional ground state. We investigate both numerically and experimentally the optimization of Raman sideband cooling strategies and propose an efficient one, which can simplify the experimental setup as well as reduce the number of cooling pulses. Several cooling schemes are tested and compared through numerical simulations. The simulation result shows that the fixed-width pulses and varied-width pulses have almost the same efficiency for both the first-order and the second-order Raman sideband cooling. The optimized strategy is verified experimentally. A single 25Mg+ ion is trapped in a linear Paul trap and Raman sideband cooled, and the achieved average vibrational quantum numbers under different cooling strategies are evaluated. A good agreement between the experimental result and the simulation result is obtained.

Gender Differences among Sagittal Plane Knee Kinematic and Ground Reaction Force Characteristics during a Rapid Sprint and Cut Maneuver

ERIC Educational Resources Information Center

James, C. Roger; Sizer, Phillip S.; Starch, David W.; Lockhart, Thurmon E.; Slauterbeck, James

2004-01-01

Women are more prone to anterior cruciate ligament (ACL) injury during cutting sports than men. The purpose of this study was to examine knee kinematic and ground reaction forces (GRF) differences between genders during cutting. Male and female athletes performed cutting trials while force platform and video data were recorded (180 Hz).…

Toward a closer integration of magnetospheric research: Magnetospheric currents inferred from ground-based magnetic data

NASA Astrophysics Data System (ADS)

Akasofu, S.-I.; Kamide, Y.

1998-07-01

A new approach is needed to advance magnetospheric physics in the future to achieve a much closer integration than in the past among satellite-based researchers, ground-based researchers, and theorists/modelers. Specifically, we must find efficient ways to combine two-dimensional ground-based data and single points satellite-based data to infer three-dimensional aspects of magnetospheric disturbances. For this particular integration purpose, we propose a new project. It is designed to determine the currents on the magnetospheric equatorial plane from the ionospheric current distribution which has become available by inverting ground-based magnetic data from an extensive, systematic network of observations, combined with ground-based radar measurements of ionospheric parameters, and satellite observations of auroras, electric fields, and currents. The inversion method is based on the KRM/AMIE algorithms. In the first part of the paper, we extensively review the reliability and accuracy of the KRM and AMIE algorithms and conclude that the ionospheric quantities thus obtained are accurate enough for the next step. In the second part, the ionospheric current distribution thus obtained is projected onto the equatorial plane. This process requires a close cooperation with modelers in determining an accurate configuration of the magnetospheric field lines. If we succeed in this projection, we should be able to study the changing distribution of the currents in a vast region of the magnetospheric equatorial plane for extended periods with a time resolution of about 5 min. This process requires a model of the magnetosphere for the different phases of the magnetospheric substorm. Satellite-based observations are needed to calibrate the projection results. Agreements and disagreements thus obtained will be crucial for theoretical studies of magnetospheric plasma convection and dynamics, particularly in studying substorms. Nothing is easy in these procedures. However, unless we can overcome the associated difficulties, we may not be able to make distinct progresses. We believe that the proposed project is one way to draw the three groups closer together in advancing magnetospheric physics in the future. It is important to note that the proposed project has become possible because ground-based space physics has made a major advance during the last decade.

Seepage through a hazardous-waste trench cover

USGS Publications Warehouse

Healy, R.W.

1989-01-01

Water movement through a waste-trench cover under natural conditions at a low-level radioactive waste disposal site in northwestern Illinois was studied from July 1982 to June 1984, using tensiometers, a moisture probe, and meteorological instruments. Four methods were used to estimate seepage: the Darcy, zero-flux plane, surface-based water-budget, and groundwater-based water-budget methods. Annual seepage estimates ranged from 48 to 216 mm (5-23% of total precipitation), with most seepage occurring in spring. The Darcy method, although limited in accuracy by uncertainty in hydraulic conductivity, was capable of discretizing seepage in space and time and indicated that seepage varied by almost an order of magnitude across the width of the trench. Lowest seepage rates occurred near the center of the cover, where seepage was gradual. Highest rates occurred along the edge of the cover, where seepage was highly episodic, with 84% of the total there being traced to wetting fronts from 28 individual storms. Limitations of the zero-flux-plane method were severe enough for the method to be judged inappropriate for use in this study.Water movement through a waste-trench cover under natural conditions at a low-level radioactive waste disposal site in northwestern Illinois was studied from July 1982 to June 1984, using tensiometers, a moisture probe, and meteorological instruments. Four methods were used to estimate seepage: the Darcy, zero-flux plane, surface-based water-budget, and groundwater-based water-budget methods. Annual seepage estimates ranged from 48 to 216mm (5-23% of total precipitation), with most seepage occurring in spring. The Darcy method, although limited in accuracy by uncertainty in hydraulic conductivity, was capable of discretizing seepage in space and time and indicated that seepage varied by almost an order of magnitude across the width of the trench. Lowest seepage rates occurred near the center of the cover, where seepage was gradual. Highest rates occurred along the edge of the cover, where seepage was highly episodic, with 84% of the total there being traced to wetting fronts from 28 individual storms. Limitations of the zero-flux-plane method were severe enough for the method to be judged inappropriate for use in this study.

Spin structure of electron subbands in (110)-grown quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nestoklon, M. O.; Tarasenko, S. A.; Jancu, J.-M.

We present the theory of fine structure of electron states in symmetric and asymmetric zinc-blende-type quantum wells with the (110) crystallographic orientation. By combining the symmetry analysis, sp{sup 3}d{sup 5}s* tight-binding method, and envelope-function approach we obtain quantitative description of in-plane wave vector, well width and applied electric field dependencies of the zero-magnetic-field spin splitting of electron subbands and extract spin-orbit-coupling parameters.

Finite element analysis of a composite crash box subjected to low velocity impact

NASA Astrophysics Data System (ADS)

Shaik Dawood, M. S. I.; Ghazilan, A. L. Ahmad; Shah, Q. H.

2017-03-01

In this work, finite element analyses using LS-DYNA had been carried out to investigate the energy absorption capability of a composite crash box. The analysed design incorporates grooves to the cross sectional shape and E-Glass/Epoxy as design material. The effects of groove depth, ridge lines, plane width, material properties, wall thickness and fibre orientation had been quantitatively analysed and found to significantly enhance the energy absorption capability of the crash box.

Characterization of coarse bainite transformation in low carbon steel during simulated welding thermal cycles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lan, Liangyun, E-mail: lanly@me.neu.edu.cn; State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819; Kong, Xiangwei

2015-07-15

Coarse austenite to bainite transformation in low carbon steel under simulated welding thermal cycles was morphologically and crystallographically characterized by means of optical microscope, transmission electron microscope and electron backscattered diffraction technology. The results showed that the main microstructure changes from a mixture of lath martensite and bainitic ferrite to granular bainite with the increase in cooling time. The width of bainitic laths also increases gradually with the cooling time. For a welding thermal cycle with relatively short cooling time (e.g. t{sub 8/5} is 30 s), the main mode of variant grouping at the scale of individual prior austenite grainsmore » changes from Bain grouping to close-packed plane grouping with the progress of phase transformation, which results in inhomogeneous distribution of high angle boundaries. As the cooling time is increased, the Bain grouping of variants becomes predominant mode, which enlarges the effective grain size of product phase. - Highlights: • Main microstructure changes and the width of lath structure increases with cooling time. • Variant grouping changes from Bain zone to close-packed plane grouping with the transformation. • The change of variant grouping results in uneven distribution of high angle grain boundary. • Bain grouping is main mode for large heat input, which lowers the density of high angle boundary.« less

A new parallel plate shear cell for in situ real-space measurements of complex fluids under shear flow.

PubMed

Wu, Yu Ling; Brand, Joost H J; van Gemert, Josephus L A; Verkerk, Jaap; Wisman, Hans; van Blaaderen, Alfons; Imhof, Arnout

2007-10-01

We developed and tested a parallel plate shear cell that can be mounted on top of an inverted microscope to perform confocal real-space measurements on complex fluids under shear. To follow structural changes in time, a plane of zero velocity is created by letting the plates move in opposite directions. The location of this plane is varied by changing the relative velocities of the plates. The gap width is variable between 20 and 200 microm with parallelism better than 1 microm. Such a small gap width enables us to examine the total sample thickness using high numerical aperture objective lenses. The achieved shear rates cover the range of 0.02-10(3) s(-1). This shear cell can apply an oscillatory shear with adjustable amplitude and frequency. The maximum travel of each plate equals 1 cm, so that strains up to 500 can be applied. For most complex fluids, an oscillatory shear with such a large amplitude can be regarded as a continuous shear. We measured the flow profile of a suspension of silica colloids in this shear cell. It was linear except for a small deviation caused by sedimentation. To demonstrate the excellent performance and capabilities of this new setup we examined shear induced crystallization and melting of concentrated suspensions of 1 microm diameter silica colloids.

Comparison of Asymmetric and Ice-cream Cone Models for Halo Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Na, H.; Moon, Y.

2011-12-01

Halo coronal mass ejections (HCMEs) are major cause of the geomagnetic storms. To minimize the projection effect by coronagraph observation, several cone models have been suggested: an ice-cream cone model, an asymmetric cone model etc. These models allow us to determine the three dimensional parameters of HCMEs such as radial speed, angular width, and the angle between sky plane and central axis of the cone. In this study, we compare these parameters obtained from different models using 48 well-observed HCMEs from 2001 to 2002. And we obtain the root mean square error (RMS error) between measured projection speeds and calculated projection speeds for both cone models. As a result, we find that the radial speeds obtained from the models are well correlated with each other (R = 0.86), and the correlation coefficient of angular width is 0.6. The correlation coefficient of the angle between sky plane and central axis of the cone is 0.31, which is much smaller than expected. The reason may be due to the fact that the source locations of the asymmetric cone model are distributed near the center, while those of the ice-cream cone model are located in a wide range. The average RMS error of the asymmetric cone model (85.6km/s) is slightly smaller than that of the ice-cream cone model (87.8km/s).

Detecting short circuits during assembly

NASA Technical Reports Server (NTRS)

Deboo, G. J.

1980-01-01

Detector circuit identifies shorts between bus bars of electronic equipment being wired. Detector sounds alarm and indicates which planes are shorted. Power and ground bus bars are scanned continuously until short circuit occurs.

Source Models of the June 17th, 2007 Kilauea Intrusion: Monte Carlo Optimization

NASA Astrophysics Data System (ADS)

Sinnett, D. K.; Montgomery-Brown, E. D.; Segall, P.; Miklius, A.; Poland, M.; Yun, S.; Zebker, H.

2007-12-01

Father's Day, 17 June 2007, marked the beginning of the 56th episode of the ongoing eruption of Kilauea volcano, Hawaii. The episode culminated in a short-lived eruption approximately 6 km west of Pu\\`{}u \\`{}O\\`{}o and 13 km southeast of Kilauea summit. The interruption of magma supply to, and withdrawal from, the reservoir beneath Pu\\`{}u \\`{}O\\`{}o caused cessation of activity and ~100 m of crater floor subsidence there. The continuous and campaign GPS, electronic tiltmeter, and seismic networks, as well as InSAR captured the episode in fine detail. Visual inspection of the data show subsidence at Kilauea summit and Pu\\`{}u \\`{}O\\`{}o, which fed the inflating dike. We began by modeling the intrusion with a Mogi source beneath Kilauea summit and a dislocation with uniform opening beneath the east rift zone embedded in an isotropic, homogenous, elastic, half space. We invert for the 12 source parameters (length, width, depth, dip, strike, horizontal position, and opening of the dike, and position, depth, and volume change of the Mogi source) using Monte Carlo optimization. The inversion used three component displacement data from 23 continuous and campaign GPS stations, diurnally and tidally filtered tilt from 6 stations, and an ENVISAT InSAR interferogram spanning 04/12/07 to 06/21/07 decimated using a quadtree algorithm. The optimum model included ~-4.1 * 106 m3 of volume loss from a reservoir 3 km beneath the summit, and a total dike volume of ~19*106 m3 (~4.84 km length x 2.45 km width x 1.6 m opening at 2.4 km depth). The discrepancy between summit volume loss and total dike volume suggests that other sources must have fed the dike. A crude estimate of volume loss from Pu\\`{}u \\`{}O\\`{}o is 8.5*106 m3 accounting for ~ 66% of the volume of the dike. The eruption site lies inside the eastern edge of the model, and ~0.5 km to the south of the best fit dike top. The best fit dike top parallels the northern margin of an area of ground cracking near Makaopuhui and terminates at its western margin near Mauna Ulu. The western termination is ~2.5 km east of the westernmost observed ground cracks. Within 95% bounds the dike top may intersect the eruption area and extend to all regions of ground cracking. It is also interesting to note that this dike is located in an area between the 1997 and 1999 intrusions. The best fit single dislocation model explains only 35% of the variance in the data. This is in part due to the inadequacies of a single planar dike with uniform opening to explain surface deformation and perhaps to inelastic deformation associated with ground cracking near the western edge of the dike. Models with distributed opening, in which the dike plane honors the optimization results as well as the region of decorrelation in the ENVISAT interferogram, explain 69% of the data (Montgomery-Brown et al., this session).

Angular-dependent Raman study of a- and s-plane InN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filintoglou, K.; Katsikini, M., E-mail: katsiki@auth.gr; Arvanitidis, J.

2015-02-21

Angular-dependent polarized Raman spectroscopy was utilized to study nonpolar a-plane (11{sup ¯}20) and semipolar s-plane (101{sup ¯}1) InN epilayers. The intensity dependence of the Raman peaks assigned to the vibrational modes A{sub 1}(TO), E{sub 1}(TO), and E{sub 2}{sup h} on the angle ψ that corresponds to rotation around the growth axis, is very well reproduced by using expressions taking into account the corresponding Raman tensors and the experimental geometry, providing thus a reliable technique towards assessing the sample quality. The s- and a-plane InN epilayers grown on nitridated r-plane sapphire (Al{sub 2}O{sub 3}) exhibit good crystalline quality as deduced frommore » the excellent fitting of the experimental angle-dependent peak intensities to the theoretical expressions as well as from the small width of the Raman peaks. On the contrary, in the case of the s-plane epilayer grown on non-nitridated r-plane sapphire, fitting of the angular dependence is much worse and can be modeled only by considering the presence of two structural modifications, rotated so as their c-axes are almost perpendicular to each other. Although the presence of the second variant is verified by transmission electron and atomic force microscopies, angular dependent Raman spectroscopy offers a non-destructive and quick way for its quantification. Rapid thermal annealing of this sample did not affect the angular dependence of the peak intensities. The shift of the E{sub 1}(TO) and E{sub 2}{sup h} Raman peaks was used for the estimation of the strain state of the samples.« less

Omnidirectional antenna having constant phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sena, Matthew

Various technologies presented herein relate to constructing and/or operating an antenna having an omnidirectional electrical field of constant phase. The antenna comprises an upper plate made up of multiple conductive rings, a lower ground-plane plate, a plurality of grounding posts, a conical feed, and a radio frequency (RF) feed connector. The upper plate has a multi-ring configuration comprising a large outer ring and several smaller rings of equal size located within the outer ring. The large outer ring and the four smaller rings have the same cross-section. The grounding posts ground the upper plate to the lower plate while maintainingmore » a required spacing/parallelism therebetween.« less

LINE-ABOVE-GROUND ATTENUATOR

DOEpatents

Wilds, R.B.; Ames, J.R.

1957-09-24

The line-above-ground attenuator provides a continuously variable microwave attenuator for a coaxial line that is capable of high attenuation and low insertion loss. The device consists of a short section of the line-above- ground plane type transmission lime, a pair of identical rectangular slabs of lossy material like polytron, whose longitudinal axes are parallel to and indentically spaced away from either side of the line, and a geared mechanism to adjust amd maintain this spaced relationship. This device permits optimum fineness and accuracy of attenuator control which heretofore has been difficult to achieve.

Sound Radiation from a Supersonic Jet Passing Through a Partially Open Exhaust Duct

NASA Technical Reports Server (NTRS)

Kandula, Max

2011-01-01

The radiation of sound from a perfectly expanded Mach 2.5 cold supersonic jet of 25.4 mm exit diameter flowing through a partially open rigid-walled duct with an upstream i-deflector has been studied experimentally. In the experiments, the nozzle is mounted vertically, with the nozzle exit plane at a height of 73 jet diameters above ground level. Relative to the nozzle exit plane (NEP), the location of the duct inlet is varied at 10, 5, and -1 jet diameters. Far-field sound pressure levels were obtained at 54 jet diameters above ground with the aid of acoustic sensors equally spaced around a circular arc of radius equal to 80 jet diameters from the jet axis. Data on the jet acoustic field for the partially open duct were obtained and compared with those with a free jet and with a closed duct. The results suggest that for the partially open duct the overall sound pressure level (OASPL) decreases as the distance between the NEP and the duct inlet plane decreases, while the opposite trend is observed for the closed duct. It is also concluded that the observed peak frequency in the partially open duct increases above the free jet value as the angle from the duct axis is increased, and as the duct inlet plane becomes closer to the NEP.

Safe Zone Quantification of the Third Sacral Segment in Normal and Dysmorphic Sacra.

PubMed

Hwang, John S; Reilly, Mark C; Shaath, Mohammad K; Changoor, Stuart; Eastman, Jonathan; Routt, Milton Lee Chip; Sirkin, Michael S; Adams, Mark R

2018-04-01

To quantify the osseous anatomy of the dysmorphic third sacral segment and assess its ability to accommodate internal fixation. Retrospective chart review of a trauma database. University Level 1 Trauma Center. Fifty-nine patients over the age of 18 with computed tomography scans of the pelvis separated into 2 groups: a group with normal pelvic anatomy and a group with sacral dysmorphism. The sacral osseous area was measured on computed tomography scans in the axial, coronal, and sagittal planes in normal and dysmorphic pelves. These measurements were used to determine the possibility of accommodating a transiliac transsacral screw in the third sacral segment. In the normal group, the S3 coronal transverse width averaged 7.71 mm and the S3 axial transverse width averaged 7.12 mm. The mean S3 cross-sectional area of the normal group was 55.8 mm. The dysmorphic group was found to have a mean S3 coronal transverse width of 9.49 mm, an average S3 axial transverse width of 9.14 mm, and an S3 cross-sectional area of 77.9 mm. The third sacral segment of dysmorphic sacra has a larger osseous pathway available to safely accommodate a transiliac transsacral screw when compared with normal sacra. The S3 segment of dysmorphic sacra can serve as an additional site for screw placement when treating unstable posterior pelvic ring fractures.

Wedge-shaped slice-selective adiabatic inversion pulse for controlling temporal width of bolus in pulsed arterial spin labeling

PubMed Central

Guo, Jia; Buxton, Richard B.; Wong, Eric C.

2015-01-01

Purpose In pulsed arterial spin labeling (PASL) methods, arterial blood is labeled via inverting a slab with uniform thickness, resulting in different temporal widths of boluses in vessels with different flow velocities. This limits the temporal resolution and signal-to-noise ratio (SNR) efficiency gains in PASL-based methods intended for high temporal resolution and SNR efficiency, such as Turbo-ASL and Turbo-QUASAR. Theory and Methods A novel wedge-shaped (WS) adiabatic inversion pulse is developed by adding in-plane gradient pulses to a slice-selective (SS) adiabatic inversion pulse to linearly modulate the inversion thicknesses at different locations while maintaining the adiabatic properties of the original pulse. A hyperbolic secant (HS) based WS inversion pulse was implemented. Its performance was tested in simulations, phantom and human experiments, and compared to an SS HS inversion pulse. Results Compared to the SS inversion pulse, the WS inversion pulse is capable of inducing different inversion thicknesses at different locations. It can be adjusted to generate a uniform temporal width of boluses in arteries at locations with different flow velocities. Conclusion The WS inversion pulse can be used to control the temporal widths of labeled boluses in PASL experiments. This should benefit PASL experiments by maximizing labeling duty cycle, and improving temporal resolution and SNR efficiency. PMID:26451521

Dependence of SOL widths on plasma parameters in NSTX

NASA Astrophysics Data System (ADS)

Ahn, Joon-Wook; Maingi, Rajesh; Boedo, Jose; Soukhanovskii, Vlad; Leblanc, Ben; Kaita, Robert

2008-11-01

The dependence of various upstream Scrape-Off Layer (SOL) widths on the line-averaged density (n e), plasma current (Ip), and power into the SOL (PSOL) for H-mode plasmas was investigated, using the mid-plane fast reciprocating probe and Thomson scattering diagnostics, in the National Spherical Torus Experiment (NSTX). The heat flux width (λq) at the divertor plate, measured by the IR camera, was also measured and compared with the upstream SOL widths. The edge density profile remains fixed during the H-mode, such that the separatrix density is constant even though n e is ramping. Thus λq, λTe, and λne are insensitive to n e. λTe and λjsat have strong negative dependence on Ip, whereas there was only a very weak change in λne when Ip was varied. These empirical results have been compared with scaling laws in the literature. The λTe dependence on Ip is consistent with an H-mode λTe scaling law, while the insensitivity of λne to n e is not consistent with the λne scaling law. Dependence of decay lengths on plasma parameters in a wide range of plasma conditions will be presented. This work was supported by the US Department of Energy, contract numbers DE-FG02-03ER54731, DE-AC02-76CH03073, DE-AC05-00OR22725, and DE-AC52-07NA27344.

Three-body model for the two-neutron emission of Be 16 [Three-body model for the two-neutron decay of 16Be

DOE PAGES

Lovell, A. E.; Nunes, F. M.; Thompson, I. J.

2017-03-10

While diproton emission was first theorized in 1960 and first measured in 2002, it was first observed only in 2012. The measurement of 14Be in coincidence with two neutrons suggests that 16Be does decay through the simultaneous emission of two strongly correlated neutrons. In this study, we construct a full three-body model of 16Be (as 14Be + n + n) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Here, in order to describe the three-body system, effective n – 14Be potentials were constructed, constrained by the experimental information on 15Be.more » The hyperspherical R-matrix method was used to solve the three-body scattering problem, and the resonance energy of 16Be was extracted from a phase-shift analysis. As a result, in order to reproduce the experimental resonance energy of 16Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of 16Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. In conclusion, our results confirm a dineutron structure for 16Be, dependent on the internal structure of the subsystem 15Be.« less

Three-body model for the two-neutron emission of Be 16 [Three-body model for the two-neutron decay of 16Be

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lovell, A. E.; Nunes, F. M.; Thompson, I. J.

While diproton emission was first theorized in 1960 and first measured in 2002, it was first observed only in 2012. The measurement of 14Be in coincidence with two neutrons suggests that 16Be does decay through the simultaneous emission of two strongly correlated neutrons. In this study, we construct a full three-body model of 16Be (as 14Be + n + n) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Here, in order to describe the three-body system, effective n – 14Be potentials were constructed, constrained by the experimental information on 15Be.more » The hyperspherical R-matrix method was used to solve the three-body scattering problem, and the resonance energy of 16Be was extracted from a phase-shift analysis. As a result, in order to reproduce the experimental resonance energy of 16Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of 16Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. In conclusion, our results confirm a dineutron structure for 16Be, dependent on the internal structure of the subsystem 15Be.« less

Experimental study of heating scheme effect on the inner divertor power footprint widths in EAST lower single null discharges

NASA Astrophysics Data System (ADS)

Deng, G. Z.; Xu, J. C.; Liu, X.; Liu, X. J.; Liu, J. B.; Zhang, H.; Liu, S. C.; Chen, L.; Yan, N.; Feng, W.; Liu, H.; Xia, T. Y.; Zhang, B.; Shao, L. M.; Ming, T. F.; Xu, G. S.; Guo, H. Y.; Xu, X. Q.; Gao, X.; Wang, L.

2018-04-01

A comprehensive work of the effects of plasma current and heating schemes on divertor power footprint widths is carried out in the experimental advanced superconducting tokamak (EAST). The divertor power footprint widths, i.e., the scrape-off layer heat flux decay length λ q and the heat spreading S, are crucial physical and engineering parameters for fusion reactors. Strong inverse scaling of λ q and S with plasma current have been demonstrated for both neutral beam (NB) and lower hybrid wave (LHW) heated L-mode and H-mode plasmas at the inner divertor target. For plasmas heated by the combination of the two kinds of auxiliary heating schemes (NB and LHW), the divertor power widths tend to be larger in plasmas with higher ratio of LHW power. Comparison between experimental heat flux profiles at outer mid-plane (OMP) and divertor target for NB heated and LHW heated L-mode plasmas reveals that the magnetic topology changes induced by LHW may be the main reason to the wider divertor power widths in LHW heated discharges. The effect of heating schemes on divertor peak heat flux has also been investigated, and it is found that LHW heated discharges tend to have a lower divertor peak heat flux compared with NB heated discharges under similar input power. All these findings seem to suggest that plasmas with LHW auxiliary heating scheme are better heat exhaust scenarios for fusion reactors and should be the priorities for the design of next-step fusion reactors like China Fusion Engineering Test Reactor.

Age- and gender-related characteristics of the pubic symphysis and triradiate cartilage in pediatric computed tomography.

PubMed

Bayer, Jörg; Neubauer, Jakob; Saueressig, Ulrich; Südkamp, Norbert P; Reising, Kilian

2016-11-01

There is little information on the pubic symphysis' normal CT appearance in children. We sought to generate age-, gender- and maturity-related symphyseal width appearances in CT scans. Pelvic CT scans performed for any reason during a 6-year period in patients younger than 18 years were retrospectively analyzed. The symphysis width was measured in the axial plane and the triradiate cartilage was classified as open or closed. Four hundred twenty-seven CT scans were evaluated and 350 remained for analysis. Age- and gender-related measurements of the symphysis width are illustrated on various centile graphs. When grouping children by age in years 0-6, 7-11, 12-15 and 16-17, mean (standard deviation) symphysis width was 5.4 mm (0.9), 5.3 mm (1.1), 4.1 mm (1.1) and 3.5 mm (1.0), respectively, in girls and 5.9 mm (1.3), 5.4 mm (1.2), 5.2 mm (1.1) and 4.0 mm (1.0), respectively, in boys. Boys and girls were significantly different in the age groups 12-15 years (P<0.001) and 16-17 years (P=0.04). In the mature pelvis, the symphyseal gap is significantly (P<0.001) shorter in both genders, and in girls compared to boys (P=0.04). The pubic symphysis width in children differs according to age, gender and maturity. The reference values published herein may help detect symphyseal injury.

Electrical-transport properties and microwave device performance of sputtered TlCaBaCuO superconducting thin films

NASA Technical Reports Server (NTRS)

Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

1992-01-01

The paper describes the processing and electrical transport measurements for achieving reproducible high-Tc and high-Jc sputtered TlCaBaCuO thin films on LaAlO3 substrates, for microelectronic applications. The microwave properties of TlCaBaCuO thin films were investigated by designing, fabricating, and characterizing microstrip ring resonators with a fundamental resonance frequency of 12 GHz on 10-mil-thick LaAlO3 substrates. Typical unloaded quality factors for a ring resonator with a superconducting ground plane of 0.3 micron-thickness and a gold ground plane of 1-micron-thickness were above 1500 at 65 K. Typical values of penetration depth at 0 K in the TlCaBaCuO thin films were between 7000 and 8000 A.

Microwave switching power divider. [antenna feeds

NASA Technical Reports Server (NTRS)

Stockton, R. J.; Johnson, R. W. (Inventor)

1981-01-01

A pair of parallel, spaced-apart circular ground planes define a microwave cavity with multi-port microwave power distributing switching circuitry formed on opposite sides of a thin circular dielectric substrate disposed between the ground planes. The power distributing circuitry includes a conductive disk located at the center of the substrate and connected to a source of microwave energy. A high speed, low insertion loss switching diode and a dc blocking capacitor are connected in series between the outer end of a transmission line and an output port. A high impedance, microwave blocking dc bias choke is connected between each switching diode and a source of switching current. The switching source forward biases the diodes to couple microwave energy from the conductive disk to selected output ports and, to associated antenna elements connected to the output ports to form a synthesized antenna pattern.

Shear sensing based on a microstrip patch antenna

NASA Astrophysics Data System (ADS)

Mohammad, I.; Huang, H.

2012-10-01

A microstrip patch antenna sensor was studied for shear sensing with a targeted application of measuring plantar shear distribution on a diabetic foot. The antenna shear sensor consists of three components, namely an antenna patch, a soft foam substrate and a slotted ground plane. The resonant frequency of the antenna sensor is sensitive to the overlapping length between the slot in the ground plane and the antenna patch. A shear force applied along the direction of the slot deforms the foam substrate and causes a change in the overlapping length, which can be detected from the antenna frequency shift. The antenna shear sensor was designed based on simulated antenna frequency response and validated by experiments. Experimental results indicated that the antenna sensor exhibits high sensitivity to shear deformation and responds to the applied shear loads with excellent linearity and repeatability.

Stand-off transmission lines and method for making same

DOEpatents

Tuckerman, D.B.

1991-05-21

Standoff transmission lines in an integrated circuit structure are formed by etching away or removing the portion of the dielectric layer separating the microstrip metal lines and the ground plane from the regions that are not under the lines. The microstrip lines can be fabricated by a subtractive process of etching a metal layer, an additive process of direct laser writing fine lines followed by plating up the lines or a subtractive/additive process in which a trench is etched over a nucleation layer and the wire is electrolytically deposited. Microstrip lines supported on freestanding posts of dielectric material surrounded by air gaps are produced. The average dielectric constant between the lines and ground plane is reduced, resulting in higher characteristic impedance, less crosstalk between lines, increased signal propagation velocities, and reduced wafer stress. 16 figures.

Experimental investigation of five parallel plane jets with variation of Reynolds number and outlet conditions

NASA Astrophysics Data System (ADS)

Daubner, Tomas; Kizhofer, Jens; Dinulescu, Mircea

2018-06-01

This article describes an experimental investigation in the near field of five parallel plane jets. The study applies 2D Particle Image Velocimetry (PIV) for ventilated and unventilated jets, where ventilated means exiting into a duct with expansion ratio 3.5 and unventilated means exiting to the free atmosphere. Results are presented for Reynolds numbers 1408, 5857 and 10510. The Reynolds number is calculated for the middle channel and is based on the height of the nozzle (channel) equivalent diameter 2h. All characteristic regions of the methodology to describe multiple interacting jets are observed by the PIV measurements - converging, merging and combined. Each of the five parallel channels has an aspect ratio of 25 defined as nozzle width (w) to height (h). The channels have a length of 185 times the channel height guaranteeing a fully developed velocity profile at the exit from the channel. Spacing between the single plane jets is 3 times the channel height. The near field of multiple mixing jets is depended on outlet nozzle geometry. Blunt geometry of the nozzle was chosen (sudden contraction).

Backscattering enhancement with a finite beam width for millimeter-wavelength weather radars

NASA Astrophysics Data System (ADS)

Kobayashi, Satoru; Tanelli, Simone; Iguchi, Toshio; Im, Eastwood

2004-12-01

Backscattering enhancement from random hydrometeors should increase as wavelengths of radars reach millimeter regions. For 95 GHz radars, the reflectivity of backscattering is expected to increase by 2 dB, due to multiple scattering including backscattering enhancement, for water droplets of diameter of 1 mm with a density of 5 x 103 m-3. Previous theoretical studies of backscattering enhancement considered infinitely extending plane waves. In this paper, we expand the theory to spherical waves with a Gaussian antenna pattern, including depolarizing effects. While the differences from the plane wave results are not great when the optical thickness is small, as the latter increases the differences become significant, and essentially depend on the ratio of radar footprint radius to the mean free path of hydrometeors. In this regime, for a radar footprint that is smaller than the mean free path, the backscattering-enhancement reflectivity corresponding to spherical waves is significantly less pronounced than in the case of the plane wave theory. Hence this reduction factor must be taken into account when analyzing radar reflectivity factors for use in remote sensing applications.

Modeling contamination of shallow unconfined aquifers through infiltration beds

USGS Publications Warehouse

Ostendorf, D.W.

1986-01-01

We model the transport of a simply reactive contaminant through an infiltration bed and underlying shallow, one-dimensional, unconfined aquifer with a plane, steeply sloping bottom in the assumed absence of dispersion and downgradient dilution. The effluent discharge and ambient groundwater flow under the infiltration beds are presumed to form a vertically mixed plume marked by an appreciable radial velocity component in the near field flow region. The near field analysis routes effluent contamination as a single linear reservoir whose output forms a source plane for the one-dimensional, far field flow region downgradient of the facility; the location and width of the source plane reflect the relative strengths of ambient flow and effluent discharge. We model far field contaminant transport, using an existing method of characteristics solution with frame speeds modified by recharge, bottom slope, and linear adsorption, and concentrations reflecting first-order reaction kinetics. The near and far field models simulate transport of synthetic detergents, chloride, total nitrogen, and boron in a contaminant plume at the Otis Air Force Base sewage treatment plant in Barnstable County, Massachusetts, with reasonable accuracy.

Effects of the computational domain on the secondary flow in turbulent plane Couette flow

NASA Astrophysics Data System (ADS)

Gai, Jie; Xia, Zhen-Hua; Cai, Qing-Dong

2015-10-01

A series of direct numerical simulations of the fully developed plane Couette flow at a Reynolds number of 6000 (based on the relative wall speed and half the channel height h) with different streamwise and spanwise lengths are conducted to investigate the effects of the computational box sizes on the secondary flow (SF). Our focuses are the number of counter-rotating vortex pairs and its relationship to the statistics of the mean flow and the SF in the small and moderate computational box sizes. Our results show that the number of vortex pairs is sensitive to the computational box size, and so are the slope parameter, the rate of the turbulent kinetic energy contributed by the SF, and the ratio of the kinetic energy of the SF to the total kinetic energy. However, the averaged spanwise width of each counter-rotating vortex pair in the plane Couette flow is found, for the first time, within 4(1 ± 0.25)h despite the domain sizes. Project supported by the National Natural Science Foundation of China (Grant Nos. 11221061, 11272013, and 11302006).

A comparative study of stabilizing control of a planer electromagnetic levitation using PID and LQR controllers

NASA Astrophysics Data System (ADS)

Yaseen, Mundher H. A.

Magnetic levitation is a technique to suspend an object without any mechanical support. The main objective of this study is to demonstrate stabilized closed loop control of 1-DOF Maglev experimentally using real-time control simulink feature of (SIMLAB) microcontroller. Proportional Integral Derivative (PID) and Linear Quadratic Regulator (LQR) controllers are employed to examine the stability performance of the Maglev control system under effect of unbalanced change of load and wave signal on Maglev plane. The effect of unbalanced change of applied load on single point, line and plane are presented. Furthermore, in order to study the effect of sudden change in input signal, the input of wave signal has been applied on all points of the prototype maglev plate simultaneously. The results of pulse width modulation (PWM) reveal that the control system using LQR controller provides faster response to adjust the levitated plane comparing to PID controller. Moreover, the air gap distance that controlled using PID controller is rather stable with little oscillation. Meanwhile, LQR controller provided more stability and homogeneous response.

Effect of grain alignment on magnetic properties of Hg(Re)-1223 superconductors

NASA Astrophysics Data System (ADS)

Sakamoto, N.; Noguchi, S.; Akune, T.; Matsumoto, Y.

2002-08-01

Alignment of HgBa 2Ca 2Cu 3Re 0.2O y (Hg(Re)-1223) powders was made in epoxy resin under a high magnetic field of 10 T to be confirmed by X-ray analysis. DC magnetizations and AC susceptibilities of the grain aligned specimen were measured by SQUID and PPMS magnetometers at temperatures of 5-110 K and under the field of 0-14 T for both field directions of B parallel and perpendicular to ab-plane. The magnetization width for B parallel to the c-axis ΔMc showed high values at low field, decreased rather rapidly with the magnetic field compared to that for B parallel to the ab-plane ΔMab and became lower than ΔMab above a crossing field Bcr. Peak-heights of the imaginary parts of the AC susceptibilities χ″ were largest at B∥ c-axis. Non-aligned samples always showed intermediate characteristics between B∥ c-axis and B∥ ab-plane. Irreversibility fields of all samples were also evaluated. Correlations of the pinning mechanism with the crystal axis orientations are discussed.

Defect reduction of SiNx embedded m-plane GaN grown by hydride vapor phase epitaxy

NASA Astrophysics Data System (ADS)

Woo, Seohwi; Kim, Minho; So, Byeongchan; Yoo, Geunho; Jang, Jongjin; Lee, Kyuseung; Nam, Okhyun

2014-12-01

Nonpolar (1 0 -1 0) m-plane GaN has been grown on m-plane sapphire substrates by hydride vapor phase epitaxy (HVPE). We studied the defect reduction of m-GaN with embedded SiNx interlayers deposited by ex-situ metal organic chemical vapor deposition (MOCVD). The full-width at half-maximum values of the X-ray rocking curves for m-GaN with embedded SiNx along [1 1 -2 0]GaN and [0 0 0 1]GaN were reduced to 528 and 1427 arcs, respectively, as compared with the respective values of 947 and 3170 arcs, of m-GaN without SiNx. Cross-section transmission electron microscopy revealed that the basal stacking fault density was decreased by approximately one order to 5×104 cm-1 due to the defect blocking of the embedded SiNx. As a result, the near band edge emission intensities of the room-temperature and low-temperature photoluminescence showed approximately two-fold and four-fold improvement, respectively.

Low cost impulse compatible wideband antenna

DOEpatents

Rosenbury, Erwin T.; Burke, Gerald J.; Nelson, Scott D.; Stever, Robert D.; Governo, George K.; Mullenhoff, Donald J.

2002-01-01

An antenna apparatus and method for building the antenna is disclosed. Impulse signals travel through a feed point of the antenna with respect to a ground plane. A geometric fin structure is connected to the feed point, and through a termination resistance to the ground plane. A geometric ridge structure connected to the ground is positioned with respect to the fin in order to receive and radiate electromagnetic energy from the impulse signal at a predetermined impedance and over a predetermined set of frequencies. The fin and ridge can be either a wire or a planar surface. The fin and ridge may be disposed within a radiation cavity such as a horn. The radiation cavity is constructed of stamped and etched metal sheets bent and then soldered together. The fin and ridge are also formed from metal sheets or wires. The fin is attached to the feed point and then to the cavity through a termination resistance. The ridge is attached to the cavity and disposed with respect to the fin in order to achieve a particular set of antenna characteristics.

Evolution of ground-state wave function in CeCoIn5 upon Cd or Sn doping

NASA Astrophysics Data System (ADS)

Chen, K.; Strigari, F.; Sundermann, M.; Hu, Z.; Fisk, Z.; Bauer, E. D.; Rosa, P. F. S.; Sarrao, J. L.; Thompson, J. D.; Herrero-Martin, J.; Pellegrin, E.; Betto, D.; Kummer, K.; Tanaka, A.; Wirth, S.; Severing, A.

2018-01-01

We present linear polarization-dependent soft-x-ray absorption spectroscopy data at the Ce M4 ,5 edges of Cd- and Sn-doped CeCoIn5. The 4 f ground-state wave functions have been determined for their superconducting, antiferromagnetic, and paramagnetic ground states. The absence of changes in the wave functions in CeCo (In1-xCdx) 5 suggests that the 4 f -conduction-electron (c f ) hybridization is not affected by global Cd doping, thus supporting the interpretation of magnetic droplets nucleating long-range magnetic order. This is contrasted by changes in the wave function due to Sn substitution. Increasing Sn in CeCo (In1-ySny) 5 compresses the 4 f orbitals into the tetragonal plane of these materials, suggesting enhanced c f hybridization with the in-plane In(1) atoms and a homogeneous altering of the electronic structure. As these experiments show, the 4 f wave functions are a very sensitive probe of small changes in the hybridization of 4 f and conduction electrons, even conveying information about direction dependencies.

Bound-to-bound midinfrared intersubband absorption in carbon-doped GaAs /AlGaAs quantum wells

NASA Astrophysics Data System (ADS)

Malis, Oana; Pfeiffer, Loren N.; West, Kenneth W.; Sergent, A. Michael; Gmachl, Claire

2005-08-01

Bound-to-bound intersubband absorption in the valence band of modulation-doped GaAs quantum wells with digitally alloyed AlGaAs barriers was studied in the midinfrared wavelength range. A high-purity solid carbon source was used for the p-type doping. Strong narrow absorption peaks due to heavy-to-heavy hole transitions are observed with out-of-plane polarized light, and weaker broader features with in-plane polarized light. The heavy-to-heavy hole transition energy spans the spectral range between 206 to 126 meV as the quantum well width is increased from 25 to 45 Å. The experimental results are found to be in agreement with calculations of a six-band k •p model taking into account the full band structure of the digital alloy.

An efficient and cost-effective microchannel plate detector for slow neutron radiography

NASA Astrophysics Data System (ADS)

Wiggins, B. B.; Vadas, J.; Bancroft, D.; deSouza, Z. O.; Huston, J.; Hudan, S.; Baxter, D. V.; deSouza, R. T.

2018-05-01

A novel approach for efficiently imaging objects with slow neutrons in two dimensions is realized. Neutron sensitivity is achieved by use of a boron doped microchannel plate (MCP). The resulting electron avalanche is further amplified with a Z-stack MCP before being sensed by two orthogonally oriented wire planes. Coupling of the wire planes to delay lines efficiently encodes the position information as a time difference. To determine the position resolution, slow neutrons were used to illuminate a Cd-mask placed directly in front of the detector. Peaks in the resulting spectrum exhibited an average peak width of 329 μm FWHM, corresponding to an average intrinsic resolution of 216 μm. The center region of the detector exhibits a significantly better spatial resolution with an intrinsic resolution of <100 μm observed.

Nanofocus x-ray diffraction and cathodoluminescence investigations into individual core-shell (In,Ga)N/GaN rod light-emitting diodes.

PubMed

Krause, Thilo; Hanke, Michael; Cheng, Zongzhe; Niehle, Michael; Trampert, Achim; Rosenthal, Martin; Burghammer, Manfred; Ledig, Johannes; Hartmann, Jana; Zhou, Hao; Wehmann, Hergo-Heinrich; Waag, Andreas

2016-08-12

Employing nanofocus x-ray diffraction, we investigate the local strain field induced by a five-fold (In,Ga)N multi-quantum well embedded into a GaN micro-rod in core-shell geometry. Due to an x-ray beam width of only 150 nm in diameter, we are able to distinguish between individual m-facets and to detect a significant in-plane strain gradient along the rod height. This gradient translates to a red-shift in the emitted wavelength revealed by spatially resolved cathodoluminescence measurements. We interpret the result in terms of numerically derived in-plane strain using the finite element method and subsequent kinematic scattering simulations which show that the driving parameter for this effect is an increasing indium content towards the rod tip.

Nanofocus x-ray diffraction and cathodoluminescence investigations into individual core-shell (In,Ga)N/GaN rod light-emitting diodes

NASA Astrophysics Data System (ADS)

Krause, Thilo; Hanke, Michael; Cheng, Zongzhe; Niehle, Michael; Trampert, Achim; Rosenthal, Martin; Burghammer, Manfred; Ledig, Johannes; Hartmann, Jana; Zhou, Hao; Wehmann, Hergo-Heinrich; Waag, Andreas

2016-08-01

Employing nanofocus x-ray diffraction, we investigate the local strain field induced by a five-fold (In,Ga)N multi-quantum well embedded into a GaN micro-rod in core-shell geometry. Due to an x-ray beam width of only 150 nm in diameter, we are able to distinguish between individual m-facets and to detect a significant in-plane strain gradient along the rod height. This gradient translates to a red-shift in the emitted wavelength revealed by spatially resolved cathodoluminescence measurements. We interpret the result in terms of numerically derived in-plane strain using the finite element method and subsequent kinematic scattering simulations which show that the driving parameter for this effect is an increasing indium content towards the rod tip.

Magnetic stripe domains of [Pt/Co/Cu]{sub 10} multilayer near spin reorientation transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, L.; Liang, J. H.; Xiao, X.

The dependence of magnetic anisotropy, magnetic domain patterns and magnetization reversal processes in [Pt/Co(t{sub Co})/Cu]{sub 10} film stack epitaxied on Cu (111) substrate have been studied as a function of the Co layer thickness t{sub Co}, by magneto-optic polar Kerr magnetometry and microscopy. We find the film undergoes spin reorientation transition from out-of-plane to in-plane as t{sub Co} increases. The SRT thickness is verified by Rotating-field Magneto-Optic Kerr effect method. The film exhibits the stripe domain structures at remanence with the width decreasing while t{sub Co} approaches SRT. As demonstrated by the first order reversal curve measurement, the magnetization reversalmore » process encompasses irreversible domain nucleation, domain annihilation at large field and reversible domain switching near remanence.« less

Earth-Facing Antenna Characterization in Complex Ground Plane/Multipath Rich Environment

NASA Technical Reports Server (NTRS)

Welch, Bryan W.; Piasecki, Marie T.

2015-01-01

The Space Communications and Navigation (SCAN) Testbed was a Software Defined Radio (SDR)-based payload launched to the International Space Station (ISS) in July of 2012. The purpose of the SCAN Testbed payload was to investigate the applicability of SDRs to NASA space missions in an operational environment, which means that a proper model for system performance in said operational space environment is a necessary condition. The SCAN Testbed has line-of-sight connections to various ground stations with its S-Band Earth-facing Near-Earth-Network Low Gain Antenna (NEN-LGA). Any previous efforts to characterize the NEN-LGA proved difficult, therefore, the NASA Glenn Research Center built its own S-Band ground station, which became operational in 2015, and has been used successfully to characterize the NEN-LGA's in-situ pattern measurements. This methodology allows for a more realistic characterization of the antenna performance, where the pattern oscillation induced by the complex ISS ground plane, as well as shadowing effects due to ISS structural blockage are included into the final performance model. This paper describes the challenges of characterizing an antenna pattern in this environment. It will also discuss the data processing, present the final antenna pattern measurements and derived model, as well as discuss various lessons learned

Earth-Facing Antenna Characterization in a Complex Ground Plane/Multipath Rich Environment

NASA Technical Reports Server (NTRS)

Welch, Bryan W.; Piasecki, Marie T.

2015-01-01

The Space Communications and Navigation (SCAN) Testbed was a Software Defined Radio (SDR)-based payload launched to the International Space Station (ISS) in July of 2012. The purpose of the SCAN Testbed payload was to investigate the applicability of SDRs to NASA space missions in an operational space environment, which means that a proper model for system performance in said operational space environment is a necessary condition. The SCAN Testbed has line-of-sight connections to various ground stations with its S-Band Earth-facing Near-Earth Network Low Gain Antenna (NEN-LGA). Any previous efforts to characterize the NEN-LGA proved difficult, therefore, the NASA Glenn Research Center built its own S-Band ground station, which became operational in 2015, and has been successfully used to characterize the NEN-LGAs in-situ pattern measurements. This methodology allows for a more realistic characterization of the antenna performance, where the pattern oscillation induced by the complex ISS ground plane, as well as shadowing effects due to ISS structural blockage are included into the final performance model. This paper describes the challenges of characterizing an antenna pattern in this environment. It will also discuss the data processing, present the final antenna pattern measurements and derived model, as well as discuss various lessons learned.

Rock sampling. [method for controlling particle size distribution

NASA Technical Reports Server (NTRS)

Blum, P. (Inventor)

1971-01-01

A method for sampling rock and other brittle materials and for controlling resultant particle sizes is described. The method involves cutting grooves in the rock surface to provide a grouping of parallel ridges and subsequently machining the ridges to provide a powder specimen. The machining step may comprise milling, drilling, lathe cutting or the like; but a planing step is advantageous. Control of the particle size distribution is effected primarily by changing the height and width of these ridges. This control exceeds that obtainable by conventional grinding.

Dust devils on Mars

NASA Astrophysics Data System (ADS)

Thomas, P.; Gierasch, P. J.

1985-10-01

Viking Orbiter photographic imagery has confirmed the occurrence of dust devils on Mars. The images were of small bright clouds with long, tapered shadows viewed from a nearly-nadir angle. Spectra of the features were consistent with dust and not condensates. A maximum height of 6.8 km and width of 1 km were measured. The dust devils appeared on smooth planes, and had average dimensions of 2 km height and 200 m diam, carrying 3000 kg of dust. The data may be of use in interpreting convective processes on earth.

Proceedings of the Antenna Applications Symposium (1982) Held at Illinois University at Urbana on 22-24 September 1982

DTIC Science & Technology

1983-01-01

1980 (this conference) attests to method , that in admittedly a phased b array context, and to method being a bit complex. Polarization control...Computation of the phase shift was made by two methods . The first used equations in Marcuvitz 4 for an E-plane waveguide bend, with changes in e i...made by adjustment of the waveguide width. The second method (Bahar-) requi-edi solving the wave equation in cylindrical coordinates. 28 Because the

Regional Survey of Structural Properties and Cementation Patterns of Fault Zones in the Northern Part of the Albuquerque Basin, New Mexico - Implications for Ground-Water Flow

USGS Publications Warehouse

Minor, Scott A.; Hudson, Mark R.

2006-01-01

Motivated by the need to document and evaluate the types and variability of fault zone properties that potentially affect aquifer systems in basins of the middle Rio Grande rift, we systematically characterized structural and cementation properties of exposed fault zones at 176 sites in the northern Albuquerque Basin. A statistical analysis of measurements and observations evaluated four aspects of the fault zones: (1) attitude and displacement, (2) cement, (3) lithology of the host rock or sediment, and (4) character and width of distinctive structural architectural components at the outcrop scale. Three structural architectural components of the fault zones were observed: (1) outer damage zones related to fault growth; these zones typically contain deformation bands, shear fractures, and open extensional fractures, which strike subparallel to the fault and may promote ground-water flow along the fault zone; (2) inner mixed zones composed of variably entrained, disrupted, and dismembered blocks of host sediment; and (3) central fault cores that accommodate most shear strain and in which persistent low- permeability clay-rich rocks likely impede the flow of water across the fault. The lithology of the host rock or sediment influences the structure of the fault zone and the width of its components. Different grain-size distributions and degrees of induration of the host materials produce differences in material strength that lead to variations in width, degree, and style of fracturing and other fault-related deformation. In addition, lithology of the host sediment appears to strongly control the distribution of cement in fault zones. Most faults strike north to north-northeast and dip 55? - 77? east or west, toward the basin center. Most faults exhibit normal slip, and many of these faults have been reactivated by normal-oblique and strike slip. Although measured fault displacements have a broad range, from 0.9 to 4,000 m, most are <100 m, and fault zones appear to have formed mainly at depths less than 1,000 m. Fault zone widths do not exceed 40 m (median width = 15.5 m). The mean width of fault cores (0.1 m) is nearly one order of magnitude less than that of mixed zones (0.75 m) and two orders of magnitude less than that of damage zones (9.7 m). Cements, a proxy for localized flow of ancient ground water, are common along fault zones in the basin. Silica cements are limited to faults that are near and strike north to northwest toward the Jemez volcanic field north of the basin, whereas carbonate fault cements are widely distributed. Coarse sediments (gravel and sand) host the greatest concentrations of cement within fault zones. Cements fill some extension fractures and, to a lesser degree, are concentrated along shear fractures and deformation bands within inner damage zones. Cements are commonly concentrated in mixed zones and inner damage zones on one side of a fault and thus are asymmetrically distributed within a fault zone, but cement does not consistently lie on the basinward side of faults. From observed spatial patterns of asymmetrically distributed fault zone cements, we infer that ancient ground-water flow was commonly localized along, and bounded by, faults in the basin. It is apparent from our study that the Albuquerque Basin contains a high concentration of faults. The geometry of, internal structure of, and cement and clay distribution in fault zones have created and will continue to create considerable heterogeneity of permeability within the basin aquifers. The characteristics and statistical range of fault zone features appear to be predictable and consistent throughout the basin; this predictability can be used in ground-water flow simulations that consider the influence of faults.

Development and Validation of a Controlled Virtual Environment for Guidance, Navigation and Control of Quadrotor UAV

DTIC Science & Technology

2013-09-01

Width Modulation QuarC Quanser Real-time Control RC Remote Controlled RPV Remotely Piloted Vehicles SLAM Simultaneous Localization and Mapping UAV...development of the following systems: 1. Navigation (GPS, Lidar , etc.) 2. Communication (Datalink) 3. Ground Control Station (GUI, software programming

Numerical analysis of propeller induced ground vortices by actuator disk model.

PubMed

Yang, Y; Veldhuis, L L M; Eitelberg, G

2018-01-01

During the ground operation of aircraft, the interaction between the propulsor-induced flow field and the ground may lead to the generation of ground vortices. Utilizing numerical approaches, the source of vorticity entering ground vortices is investigated. The results show that the production of wall-parallel components of vorticity has a strong contribution from the wall-parallel components of the pressure gradient on the wall, which is generated by the action of the propulsor. This mechanism is a supplementation for the vorticity transported from the far-field boundary layer, which has been assumed the main vorticity source in a number of previous publications. Furthermore, the quantitative prediction of the occurrence of ground vortices is performed from the numerical results. As the distance of the propeller form the ground decreases, and as the thrust of the propeller increases, ground vortices are generated from the ground and enter the propeller. In addition, the vortices which exist near the ground but does not enter the propeller plane are observed and visualized by three-dimensional data.

Ten deg off-axis tensile test for intralaminar shear characterization of fiber composites

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Sinclair, J. H.

1976-01-01

A combined theoretical and experimental investigation was conducted to assess the suitability of the 10 deg off-axis tensile test specimen for the intralaminar shear characterization of unidirectional composites. Composite mechanics, a combined-stress failure criterion, and a finite element analysis were used to determine theoretically the stress-strain variation across the specimen width and the relative stress and strain magnitudes at the 10 deg plane. Strain gages were used to measure the strain variation across the specimen width at specimen midlength and near the end tabs. Specimens from Mod-I/epoxy, T-300/epoxy, and S-glass/epoxy were used in the experimental program. It was found that the 10 deg off-axis tensile test specimen is suitable for intralaminar shear characterization and it is recommended that it should be considered as a possible standard test specimen for such a characterization.

Large-scale transport across narrow gaps in rod bundles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guellouz, M.S.; Tavoularis, S.

1995-09-01

Flow visualization and how-wire anemometry were used to investigate the velocity field in a rectangular channel containing a single cylindrical rod, which could be traversed on the centreplane to form gaps of different widths with the plane wall. The presence of large-scale, quasi-periodic structures in the vicinity of the gap has been demonstrated through flow visualization, spectral analysis and space-time correlation measurements. These structures are seen to exist even for relatively large gaps, at least up to W/D=1.350 (W is the sum of the rod diameter, D, and the gap width). The above measurements appear to compatible with the fieldmore » of a street of three-dimensional, counter-rotating vortices, whose detailed structure, however, remains to be determined. The convection speed and the streamwise spacing of these vortices have been determined as functions of the gap size.« less

Dispersion-free radial transmission lines

DOEpatents

Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA

2011-04-12

A dispersion-free radial transmission line ("DFRTL") preferably for linear accelerators, having two plane conductors each with a central hole, and an electromagnetically permeable material ("EPM") between the two conductors and surrounding a channel connecting the two holes. At least one of the material parameters of relative magnetic permeability, relative dielectric permittivity, and axial width of the EPM is varied as a function of radius, so that the characteristic impedance of the DFRTL is held substantially constant, and pulse transmission therethrough is substantially dispersion-free. Preferably, the EPM is divided into concentric radial sections, with the varied material parameters held constant in each respective section but stepwise varied between sections as a step function of the radius. The radial widths of the concentric sections are selected so that pulse traversal time across each section is the same, and the varied material parameters of the concentric sections are selected to minimize traversal error.

Grating angle magnification enhanced angular sensor and scanner

NASA Technical Reports Server (NTRS)

Sun, Ke-Xun (Inventor); Byer, Robert L. (Inventor)

2009-01-01

An angular magnification effect of diffraction is exploited to provide improved sensing and scanning. This effect is most pronounced for a normal or near-normal incidence angle in combination with a grazing diffraction angle, so such configurations are preferred. Angular sensitivity can be further enhanced because the width of the diffracted beam can be substantially less than the width of the incident beam. Normal incidence configurations with two symmetric diffracted beams are preferred, since rotation and vertical displacement can be readily distinguished. Increased sensitivity to vertical displacement can be provided by incorporating an interferometer into the measurement system. Quad cell detectors can be employed to provide sensitivity to rotation about the grating surface normal. A 2-D grating can be employed to provide sensitivity to angular displacements in two different planes (e.g., pitch and yaw). Combined systems can provide sensitivity to vertical displacement and to all three angular degrees of freedom.

Opening and closing of band gaps in magnonic waveguide by rotating the triangular antidots - A micromagnetic study

NASA Astrophysics Data System (ADS)

Vivek, T.; Bhoomeeswaran, H.; Sabareesan, P.

2018-05-01

Spin waves in ID periodic triangular array of antidots are encarved in a permalloy magnonic waveguide is investigated through micromagnetic simulation. The effect of the rotating array of antidots and in-plane rotation of the scattering centers on the band structure are investigated, to indicate new possibilities of fine tuning of spin-wave filter pass and stop bands. The results show that, the opening and closing of band gaps paves a way for band pass and stop filters on waveguide. From the results, the scattering center and strong spatial distribution field plays crucible role for controlling opening and closing bandgap width of ˜12 GHz for 0° rotation. We have obtained a single narrow bandgap of width 1GHz is obtained for 90° rotation of the antidot. Similarly, the tunability is achieved for desired microwave applications done by rotating triangular antidots with different orientation.

Variation of high-power aluminum-wire array Z-pinch dynamics with wire number, load mass, and array radius

NASA Astrophysics Data System (ADS)

Sanford, T. W. L.; Mock, R. C.; Marder, B. M.; Nash, T. J.; Spielman, R. B.; Peterson, D. L.; Roderick, N. F.; Hammer, J. H.; De Groot, J. S.; Mosher, D.; Whitney, K. G.; Apruzese, J. P.

1997-05-01

A systematic study of annular aluminum-wire z-pinches on the Saturn accelerator shows that the quality of the implosion, (as measured by the radial convergence, the radiated energy, pulse width, and power), increases with wire number. Radiation magnetohydrodynamic (RMHC) xy simulations suggest that the implosion transitions from that of individual wire plasmas to that of a continuous plasma shell when the interwire spacing is reduced below ˜1.4 mm. In this "plasma-shell regime," many of the global radiation and plasma characteristics are in agreement with those simulated by 2D-RMHC rz simulations. In this regime, measured changes in the radiation pulse width with variations in load mass and array radius are consistent with the simulations and are explained by the development of 2D fluid motion in the rz plane. Associated variations in the K-shell yield are qualitatively explained by simple radiation-scaling models.

Breakdown in Atmospheric Pressure Plasma Jets: Nearby Grounds and Voltage Rise Time

NASA Astrophysics Data System (ADS)

Lietz, Amanda; Kushner, Mark J.

2015-09-01

Atmospheric pressure plasma jets (APPJs) are being investigated to stimulate therapeutic responses in biological systems. These responses are not always consistent. One source of variability may be the design of the APPJs - the number and placement of electrodes, pulse power format - which affects the production of reactive species. In this study, the consequences of design parameters of an APPJ were computationally investigated using nonPDPSIM, a 2 d model. The configuration is a cylindrical tube with one or two ring exterior electrodes, with or without a center pin electrode. The APPJ operates in He/O2 flowing into humid air. We found that the placement of the electrical ground on and around the system is important to the breakdown characteristics of the APPJ, and the electron density and temperature of the resulting plasma. With a single powered ring electrode, the placement of the nearest ground may vary depending on the setup, and this significantly affects the discharge. With two-ring electrodes, the nearest ground plane is well defined, however more distant ground planes can also influence the discharge. With an ionization wave (IW) that propagates out of the tube and into the plume in tens of ns, the rise time of the voltage waveform can be on the same timescale, and so variations in the voltage rise time could produce different IW properties. The effect of ground placement and voltage waveform on IW formation (ns timescales) and production of reactive neutrals (ms timescales) will be discussed. Work supported by DOE (DE-SC0001319) and NSF (CHE-1124724). Done...processed 598 records...15:12:56

Strong and radiative decays of the doubly charmed baryons

NASA Astrophysics Data System (ADS)

Xiao, Li-Ye; Wang, Kai-Lei; Lü, Qi-Fang; Zhong, Xian-Hui; Zhu, Shi-Lin

2017-11-01

We have systematically studied the strong and radiative decays of the low-lying 1 P -wave doubly charmed baryons. Some interesting observations are: (i) The states Ξcc * and Ωcc * with JP=3 /2+ have a fairly large decay rate into the Ξc cγ and Ωc cγ channels with a width ˜15 and ˜7 keV , respectively. (ii) The lowest lying excited doubly charmed baryons are dominated by the 1 P ρ mode excitations, which should be quite narrow states. They decay into the ground state with JP=1 /2+ through the radiative transitions with a significant ratio. (iii) The total decay widths of the first orbital excitations of λ mode (1 Pλ states with JP=1 /2-, 3 /2-, 5 /2-) are about Γ ˜100 MeV , and the ratio between the radiative and hadronic decay widths is about O (10-3).

Conductive Composites Made Less Expensively

NASA Technical Reports Server (NTRS)

Gaier, James R.

2005-01-01

The use of electrically conductive composite structures for electrostatic dissipation, electromagnetic interference shielding, and ground return planes could save between 30 and 90 percent of the mass of the structure, in comparison to aluminum. One strategy that has been shown to make conducting composites effectively uses intercalated graphite fiber as the reinforcement. Intercalation--the insertion of guest atoms or molecules between the graphene planes--can lower the electrical resistivity of graphite fibers by as much as a factor of 10, without sacrificing mechanical or thermal properties.

Modified Coaxial Probe Feeds for Layered Antennas

NASA Technical Reports Server (NTRS)

Fink, Patrick W.; Chu, Andrew W.; Dobbins, Justin A.; Lin, Greg Y.

2006-01-01

In a modified configuration of a coaxial probe feed for a layered printed-circuit antenna (e.g., a microstrip antenna), the outer conductor of the coaxial cable extends through the thickness of at least one dielectric layer and is connected to both the ground-plane conductor and a radiator-plane conductor. This modified configuration simplifies the incorporation of such radio-frequency integrated circuits as power dividers, filters, and low-noise amplifiers. It also simplifies the design and fabrication of stacked antennas with aperture feeds.

National Aero-Space Plane (NASP) program

NASA Technical Reports Server (NTRS)

Tank, Ming H.

1991-01-01

A program to develop the technology for reusable airbreathing hypersonic/transatmospheric vehicles is addressed. Information on the following topics is presented in viewgraph form: (1) the National Aerospace Plane (NASP) program schedule; (2) the NASP program organization; (3) competitive strategy; (4) propulsion options; (5) wind tunnel data available for NASP; (6) ground track of envelope expansion; and (7) altitude vs. Mach number. A NASP/Space Shuttle comparison, NASP configuration matrix, and the propulsion concept of a high speed scramjet are also briefly addressed.

Multiple sort flow cytometer

DOEpatents

Van den Engh, Ger; Esposito, Richard J.

1996-01-01

A flow cytometer utilizes multiple lasers for excitation and respective fluorescence of identified dyes bonded to specific cells or events to identify and verify multiple events to be sorted from a sheath flow and droplet stream. Once identified, verified and timed in the sheath flow, each event is independently tagged upon separation from the flow by an electrical charge of +60, +120, or +180 volts and passed through oppositely charged deflection plates with ground planes to yield a focused six way deflection of at least six events in a narrow plane.

Radiation monitor for liquids

DOEpatents

Koster, J.E.; Bolton, R.D.

1999-03-02

A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans. 4 figs.

Radiation monitor for liquids

DOEpatents

Koster, James E.; Bolton, Richard D.

1999-01-01

A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans.

Photometer for detection of sodium day airglow.

NASA Technical Reports Server (NTRS)

Mcmahon, D. J.; Manring, E. R.; Patty, R. R.

1973-01-01

Description of a photometer for daytime ground-based measurements of sodium airglow emission. The photometer described can be characterized by the following principal features: (1) a narrow (4.5-A) interference filter for initial discrimination; (2) cooled photomultiplier detector to reduce noise from dark current fluctuations and chopping to eliminate the average dark current; (3) a sodium vapor resonance cell to provide an effective bandpass comparable to the Doppler line width; (4) separate detection of all light transmitted by the interference filter to evaluate the Rayleigh and Mie components within the Doppler width of the resonance cell; and (5) temperature quenching of the resonance cell to evaluate and account for instrumental imperfections.

Modified Bloch equations and spectral hole burning in solids

NASA Astrophysics Data System (ADS)

Asadullina, N. Ya; Asadullin, T. Ya; Asadullin, Ya Ya

2001-06-01

On the grounds of Bloch equations modified by taking into account the power dependence of the dispersion and damping parameters, we give general expressions for hole shapes burnt in the absorption and polarization spectra of the two-level systems. The general expressions are used for detailed numerical calculations of the hole shapes and hole widths in a concrete paramagnetic system (quartz with [AlO4]0 centres). This system earlier was studied experimentally and theoretically through the transient nutation and free induction decay methods. The results on the hole width in our modified-Bloch-equations model are in good qualitative agreement with the FID data.

Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms

NASA Technical Reports Server (NTRS)

Deshpande, Manohar; Piepmeier, Jeffrey

2015-01-01

Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms. Space borne microwave remote sensors at VHF/UHF frequencies are important instruments to observe reflective properties of land surfaces through thick and heavy forestation on a global scale. One of the most cost effective ways of measuring land reflectivity at VHF/UHF frequencies is to use signals transmitted by existing communication satellites (operating at VHF/UHF band) as a signal of opportunity (SoOp) signal and passive receivers integrated with airborne/space borne platforms operating in the Low Earth Orbit (LEO). One of the critical components of the passive receiver is two antennas (one to receive only direct signal and other to receive only reflected signal) which need to have ideally high (>30dB) isolation. However, because of small size of host platforms and broad beam width of dipole antennas, achieving adequate isolation between two channels is a challenging problem and need to be solved for successful implementation of space borne SoOp technology for remote sensing. In this presentation a novel enabling VHF antenna technology for Cubesat platforms is presented to receive direct as well as reflected signal with needed isolation. The novel scheme also allows enhancing the gain of individual channels by factor of 2 without use of reflecting ground plane

Submillimeter-Wave Amplifier Module with Integrated Waveguide Transitions

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Chattopadhyay, Goutam; Pukala, David; Gaier, Todd; Soria, Mary; ManFung, King; Deal, William; Mei, Gerry; Radisic, Vesna; Lai, Richard

2009-01-01

To increase the usefulness of monolithic millimeter-wave integrated circuit (MMIC) components at submillimeter-wave frequencies, a chip has been designed that incorporates two integrated, radial E-plane probes with an MMIC amplifier in between, thus creating a fully integrated waveguide module. The integrated amplifier chip has been fabricated in 35-nm gate length InP high-electron-mobility-transistor (HEMT) technology. The radial probes were mated to grounded coplanar waveguide input and output lines in the internal amplifier. The total length of the internal HEMT amplifier is 550 m, while the total integrated chip length is 1,085 m. The chip thickness is 50 m with the chip width being 320 m. The internal MMIC amplifier is biased through wire-bond connections to the gates and drains of the chip. The chip has 3 stages, employing 35-nm gate length transistors in each stage. Wire bonds from the DC drain and gate pads are connected to off-chip shunt 51-pF capacitors, and additional off-chip capacitors and resistors are added to the gate and drain bias lines for low-frequency stability of the amplifier. Additionally, bond wires to the grounded coplanar waveguide pads at the RF input and output of the internal amplifier are added to ensure good ground connections to the waveguide package. The S-parameters of the module, not corrected for input or output waveguide loss, are measured at the waveguide flange edges. The amplifier module has over 10 dB of gain from 290 to 330 GHz, with a peak gain of over 14 dB at 307 GHz. The WR2.2 waveguide cutoff is again observed at 268 GHz. The module is biased at a drain current of 27 mA, a drain voltage of 1.24 V, and a gate voltage of +0.21 V. Return loss of the module is very good between 5 to 25 dB. This result illustrates the usefulness of the integrated radial probe transition, and the wide (over 10-percent) bandwidth that one can expect for amplifier modules with integrated radial probes in the submillimeter-regime (>300 GHz).

Light intensification effect of trailing indent crack in fused silica subsurface

NASA Astrophysics Data System (ADS)

Zhang, ChunLai; Xu, Ming; Wang, ChunDong

2015-03-01

A finite-difference time-domain algorithm was applied to solve Maxwell's equations to obtain the redistribution of an electromagnetic plane wave in the vicinity of a trailing indent crack (TIC). The roles of five geometrical parameters playing in light intensification were calculated numerically under the irradiation of a 355-nm normal incidence laser. The results show that the light intensity enhancements between the nearest neighbor pits were remarkable, which may lead to damage. The calculated results reveal that the light intensity enhancement factor ( LIEF) can be up to 11.2 when TIC is on the rear-surface. With the increase of the length as well as the depth of pits, LIEF increased. Conversely, with the increase of the axis of pits, LIEF gradually declined to a stable status. It was observed that there exists an optima width or gap, which enables LIEF to be increased dramatically and then decreased gently. By comparison, results suggest that the worst cases occur when the depth and the length are both very large, especially if the width equals to 2 l and the gap equals the width. This work provides a recommended theoretical criterion for defect inspection and classification.

Experimental and theoretical investigation of the rocking curves measured for MoK{sub α} X-ray characteristic lines in the double-crystal nondispersive scheme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchenkov, N. V., E-mail: marchenkov@ns.crys.ras.ru; Chukhovskii, F. N.; Blagov, A. E.

2015-03-15

The rocking curves (RCs) for MoK{sub α1} and MoK{sub α2} characteristic X-ray lines have been experimentally and theoretically studied in the nondispersive scheme of an X-ray double-crystal TPC-K diffractometer. The results of measurements and theoretical calculations of double-crystal RCs for characteristic X-rays from tubes with a molybdenum anode and different widths of slits show that a decrease in the slit width leads to an increase in the relative contribution of the MoK{sub α2}-line RC in comparison with the intensity of the tails of the MoK{sub α1}-line RC. It is shown that the second peak of the MoK{sub α2} line becomesmore » increasingly pronounced in the tail of the MoK{sub α1}-line RC with a decrease in the slit width. Two plane-parallel Si plates (input faces (110), diffraction vector h 〈220〉) were used as a monochromator crystal and a sample. The results of measuring double-crystal RCs are in good agreement with theoretical calculations.« less

A Finite-Orbit-Width Fokker-Planck solver for modeling of RF Current Drive in ITER

NASA Astrophysics Data System (ADS)

Petrov, Yu. V.; Harvey, R. W.

2017-10-01

The bounce-average (BA) finite-difference Fokker-Planck (FP) code CQL3D now includes the essential physics to describe the RF heating of Finite-Orbit-Width (FOW) ions in tokamaks. The FP equation is reformulated in terms of constants-of-motion coordinates, which we select to be particle speed, pitch angle, and major radius on the equatorial plane thus obtaining the distribution function directly at this location. A recent development is the capability to obtain solution simultaneously for FOW ions and Zero-Orbit-Width (ZOW) electrons. As a practical application, the code is used for simulation of alpha-particle heating by high-harmonic waves in ITER scenarios. Coupling of high harmonic or helicon fast waves power to electrons is a promising current drive (CD) scenario for high beta plasmas. However, the efficiency of current drive can be diminished by parasitic channeling of RF power into fast ions such as alphas or NBI-produced deuterons, through finite Larmor-radius effects. Based on simulations, we formulate conditions where the fast ions absorb less than 10% of RF power. Supported by USDOE Grants ER54649, ER54744, and SC0006614.

Quasi-stationary states of an electron with linearly dependent effective mass in an open nanostructure within transmission coefficient and S-matrix methods

NASA Astrophysics Data System (ADS)

Seti, Julia; Tkach, Mykola; Voitsekhivska, Oxana

2018-03-01

The exact solutions of the Schrödinger equation for a double-barrier open semiconductor plane nanostructure are obtained by using two different approaches, within the model of the rectangular potential profile and the continuous position-dependent effective mass of the electron. The transmission coefficient and scattering matrix are calculated for the double-barrier nanostructure. The resonance energies and resonance widths of the electron quasi-stationary states are analyzed as a function of the size of the near-interface region between wells and barriers, where the effective mass linearly depends on the coordinate. It is established that, in both methods, the increasing size affects in a qualitatively similar way the spectral characteristics of the states, shifting the resonance energies into the low- or high-energy region and increasing the resonance widths. It is shown that the relative difference of resonance energies and widths of a certain state, obtained in the model of position-dependent effective mass and in the widespread abrupt model in physically correct range of near-interface sizes, does not exceed 0.5% and 5%, respectively, independently of the other geometrical characteristics of the structure.

Using Curved Crystals to Study Terrace-Width Distributions.

NASA Astrophysics Data System (ADS)

Einstein, Theodore L.

Recent experiments on curved crystals of noble and late transition metals (Ortega and Juurlink groups) have renewed interest in terrace width distributions (TWD) for vicinal surfaces. Thus, it is timely to discuss refinements of TWD analysis that are absent from the standard reviews. Rather than by Gaussians, TWDs are better described by the generalized Wigner surmise, with a power-law rise and a Gaussian decay, thereby including effects evident for weak step repulsion: skewness and peak shifts down from the mean spacing. Curved crystals allow analysis of several mean spacings with the same substrate, so that one can check the scaling with the mean width. This is important since such scaling confirms well-established theory. Failure to scale also can provide significant insights. Complicating factors can include step touching (local double-height steps), oscillatory step interactions mediated by metallic (but not topological) surface states, short-range corrections to the inverse-square step repulsion, and accounting for the offset between adjacent layers of almost all surfaces. We discuss how to deal with these issues. For in-plane misoriented steps there are formulas to describe the stiffness but not yet the strength of the elastic interstep repulsion. Supported in part by NSF-CHE 13-05892.

High internal quantum efficiency ultraviolet to green luminescence peaks from pseudomorphic m-plane Al{sub 1−x}In{sub x}N epilayers grown on a low defect density m-plane freestanding GaN substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chichibu, S. F., E-mail: chichibulab@yahoo.co.jp; Hazu, K.; Furusawa, K.

2014-12-07

Structural and optical qualities of half-a-μm-thick m-plane Al{sub 1−x}In{sub x}N epilayers grown by metalorganic vapor phase epitaxy were remarkably improved via coherent growth on a low defect density m-plane freestanding GaN substrate prepared by hydride vapor phase epitaxy. All the epilayers unexceptionally suffer from uniaxial or biaxial anisotropic in-plane stress. However, full-width at half-maximum values of the x-ray ω-rocking curves were nearly unchanged as the underlayer values being 80 ∼ 150 arc sec for (101{sup ¯}0) and (101{sup ¯}2) diffractions with both 〈0001〉 and 〈112{sup ¯}0〉 azimuths, as long as pseudomorphic structure was maintained. Such Al{sub 1−x}In{sub x}N epilayers commonly exhibited a broadmore » but predominant luminescence peak in ultraviolet (x ≤ 0.14) to green (x = 0.30) wavelengths. Its equivalent value of the internal quantum efficiency at room temperature was as high as 67% for x = 0.14 and 44% for x = 0.30. Because its high-energy cutoff commonly converged with the bandgap energy, the emission peak is assigned to originate from the extended near-band-edge states with strong carrier localization.« less

Processing electronic photos of Mercury produced by ground based observation

NASA Astrophysics Data System (ADS)

Ksanfomality, Leonid

New images of Mercury have been obtained by processing of ground based observations that were carried out using the short exposure technique. The disk of the planet extendeds usually from 6 to 7 arc seconds, with the linear size of the image in a focal plane of the telescope about 0.3-0.5 mm on the average. Processing initial millisecond electronic photos of the planet is very labour-consuming. Some features of processing of initial millisecond electronic photos by methods of correlation stacking were considered in (Ksanfomality et al., 2005; Ksanfomality and Sprague, 2007). The method uses manual selection of good photos including a so-called pilot- file, the search for which usually must be done manually. The pilot-file is the most successful one, in opinion of the operator. It defines the future result of the stacking. To change pilot-files increases the labor of processing many times. Programs of processing analyze the contents of a sample, find in it any details, and search for recurrence of these almost imperceptible details in thousand of other stacking electronic pictures. If, proceeding from experience, the form and position of a pilot-file still can be estimated, the estimation of a reality of barely distinct details in it is somewhere in between the imaging and imagination. In 2006-07 some programs of automatic processing have been created. Unfortunately, the efficiency of all automatic programs is not as good as manual selection. Together with the selection, some other known methods are used. The point spread function (PSF) is described by a known mathematical function which in its central part decreases smoothly from the center. Usually the width of this function is accepted at a level 0.7 or 0.5 of the maxima. If many thousands of initial electronic pictures are acquired, it is possible during their processing to take advantage of known statistics of random variables and to choose the width of the function at a level, say, 0.9 maxima. Then the resolution of the image improves appreciably. The essential element of processing is the mathematical model of unsharp mask. But this is a two-edged instrument. The result depends on a choice of the size of the mask. If the size is too small, all low spatial frequencies will be lost, and the image becomes grey uniformly; on the contrary, if the size of the unsharp mask is too great, all fine details disappear. In some cases the compromise in selection of parameters of the unsharp mask becomes critical.

Waveguide Transition for Submillimeter-Wave MMICs

NASA Technical Reports Server (NTRS)

Leong, Kevin M.; Deal, William R.; Radisic, Vesna; Mei, Xiaobing; Uyeda, Jansen; Lai, Richard; Fung, King Man; Gaier, Todd C.

2009-01-01

An integrated waveguide-to-MMIC (monolithic microwave integrated circuit) chip operating in the 300-GHz range is designed to operate well on high-permittivity semiconductor substrates typical for an MMIC amplifier, and allows a wider MMIC substrate to be used, enabling integration with larger MMICs (power amplifiers). The waveguide-to- CBCPW (conductor-backed coplanar waveguide) transition topology is based on an integrated dipole placed in the E-plane of the waveguide module. It demonstrates low loss and good impedance matching. Measurement and simulation demonstrate that the loss of the transition and waveguide loss is less than 1-dB over a 340-to-380-GHz bandwidth. A transition is inserted along the propagation direction of the waveguide. This transition uses a planar dipole aligned with the maximum E-field of the TE10 waveguide mode as an inter face between the waveguide and the MMIC. Mode conversion between the coplanar striplines (CPS) that feed the dipole and the CBCPW transmission line is accomplished using a simple air-bridge structure. The bottom side ground plane is truncated at the same reference as the top-side ground plane, leaving the end of the MMIC suspended in air.

Source process of the 2016 Kumamoto earthquake (Mj7.3) inferred from kinematic inversion of strong-motion records

NASA Astrophysics Data System (ADS)

Yoshida, Kunikazu; Miyakoshi, Ken; Somei, Kazuhiro; Irikura, Kojiro

2017-05-01

In this study, we estimated source process of the 2016 Kumamoto earthquake from strong-motion data by using the multiple-time window linear kinematic waveform inversion method to discuss generation of strong motions and to explain crustal deformation pattern with a seismic source inversion model. A four-segment fault model was assumed based on the aftershock distribution, active fault traces, and interferometric synthetic aperture radar data. Three western segments were set to be northwest-dipping planes, and the most eastern segment under the Aso caldera was examined to be a southeast-dipping plane. The velocity structure models used in this study were estimated by using waveform modeling of moderate earthquakes that occurred in the source region. We applied a two-step approach of the inversions of 20 strong-motion datasets observed by K-NET and KiK-net by using band-pass-filtered strong-motion data at 0.05-0.5 Hz and then at 0.05-1.0 Hz. The rupture area of the fault plane was determined by applying the criterion of Somerville et al. (Seismol Res Lett 70:59-80, 1999) to the inverted slip distribution. From the first-step inversion, the fault length was trimmed from 52 to 44 km, whereas the fault width was kept at 18 km. The trimmed rupture area was not changed in the second-step inversion. The source model obtained from the two-step approach indicated 4.7 × 1019 Nm of the total moment release and 1.8 m average slip of the entire fault with a rupture area of 792 km2. Large slip areas were estimated in the seismogenic zone and in the shallow part corresponding to the surface rupture that occurred during the Mj7.3 mainshock. The areas of the high peak moment rate correlated roughly with those of large slip; however, the moment rate functions near the Earth surface have low peak, bell shape, and long duration. These subfaults with long-duration moment release are expected to cause weak short-period ground motions. We confirmed that the southeast dipping of the most eastern segment is more plausible rather than northwest-dipping from the observed subsidence around the central cones of the Aso volcano.[Figure not available: see fulltext.

Assessment of the setup dependence of detector response functions for mega-voltage linear accelerators

PubMed Central

Fox, Christopher; Simon, Tom; Simon, Bill; Dempsey, James F.; Kahler, Darren; Palta, Jatinder R.; Liu, Chihray; Yan, Guanghua

2010-01-01

Purpose: Accurate modeling of beam profiles is important for precise treatment planning dosimetry. Calculated beam profiles need to precisely replicate profiles measured during machine commissioning. Finite detector size introduces perturbations into the measured profiles, which, in turn, impact the resulting modeled profiles. The authors investigate a method for extracting the unperturbed beam profiles from those measured during linear accelerator commissioning. Methods: In-plane and cross-plane data were collected for an Elekta Synergy linac at 6 MV using ionization chambers of volume 0.01, 0.04, 0.13, and 0.65 cm3 and a diode of surface area 0.64 mm2. The detectors were orientated with the stem perpendicular to the beam and pointing away from the gantry. Profiles were measured for a 10×10 cm2 field at depths ranging from 0.8 to 25.0 cm and SSDs from 90 to 110 cm. Shaping parameters of a Gaussian response function were obtained relative to the Edge detector. The Gaussian function was deconvolved from the measured ionization chamber data. The Edge detector profile was taken as an approximation to the true profile, to which deconvolved data were compared. Data were also collected with CC13 and Edge detectors for additional fields and energies on an Elekta Synergy, Varian Trilogy, and Siemens Oncor linear accelerator and response functions obtained. Response functions were compared as a function of depth, SSD, and detector scan direction. Variations in the shaping parameter were introduced and the effect on the resulting deconvolution profiles assessed. Results: Up to 10% setup dependence in the Gaussian shaping parameter occurred, for each detector for a particular plane. This translated to less than a ±0.7 mm variation in the 80%–20% penumbral width. For large volume ionization chambers such as the FC65 Farmer type, where the cavity length to diameter ratio is far from 1, the scan direction produced up to a 40% difference in the shaping parameter between in-plane and cross-plane measurements. This is primarily due to the directional difference in penumbral width measured by the FC65 chamber, which can more than double in profiles obtained with the detector stem parallel compared to perpendicular to the scan direction. For the more symmetric CC13 chamber the variation was only 3% between in-plane and cross-plane measurements. Conclusions: The authors have shown that the detector response varies with detector type, depth, SSD, and detector scan direction. In-plane vs cross-plane scanning can require calculation of a direction dependent response function. The effect of a 10% overall variation in the response function, for an ionization chamber, translates to a small deviation in the penumbra from that of the Edge detector measured profile when deconvolved. Due to the uncertainties introduced by deconvolution the Edge detector would be preferable in obtaining an approximation of the true profile, particularly for field sizes where the energy dependence of the diode can be neglected. However, an averaged response function could be utilized to provide a good approximation of the true profile for large ionization chambers and for larger fields for which diode detectors are not recommended. PMID:20229856

An Empirical Expression for the Line Widths of Ammonia

NASA Technical Reports Server (NTRS)

Brown, Linda R.; Peterson, Dean B.

1994-01-01

The hydrogen-broadened line widths of 116 (sup 14)NH(sub 3) ground state transitions have been measured at 0.006 cm(sup -1) resolution using a Bruker spectrometer in the 24 to 210 cm(sup -1) region. The rotational variation of the experimental widths with J(sup '),K(sup ') = 1,0 to 10,10 has been reproduced to 2.4 % using an heuristically derived expression of the form

gamma = a(sub 0) + a(sub 1) J(sup ') + a (sub 2) K(sup ') + a(sub 3) J(sup ')(sup 2) + a(sub 4) J(sup ') K(sup ')

where J(sup ') and K(sup ') are the lower state symmetric top quantum numbers. This function has also been applied to the measured widths of the 58 transitions of nu(sub 1) at 3 (micro)m, each broadened by N(sub 2), O(sub 2), Ar, H(sub 2), and He. The rms of the observed minus calculated widths are 5% or better for the five foreign broadeners. The values of the fitted constants suggest that for some broadeners the expression might also be written as

gamma = a(sub 0) + b(sub 1) J(sup ') + b(sub 2)(J(sup ' )- K(sup ')) + b(sub 3) J(sup ')(J(sup ') - K(sup '))

.

Mechanism for the occurrence of paramagnetic planes within magnetically ordered cerium systems

NASA Astrophysics Data System (ADS)

Kioussis, Nicholas; Cooper, Bernard R.; Banerjea, Amitava

1988-11-01

Hybridization of moderately delocalized f electrons with band electrons gives rise to a highly anisotropic two-ion interaction. Previously it has been shown that such an interaction explains the experimentally observed unusual magnetic behavior of CeBi, yielding a phase transition from a higher-temperature type-I (↑↓) to a lower-temperature type-IA (↑↑↓↓) antiferromagnetic structure. If the hybridization-mediated interaction is the key to understanding the magnetic behavior of such moderately delocalized f-electron systems, we should expect to be able to understand on this basis the even more unusual magnetic behavior of CeSb. In CeSb, there is a sequence of magnetic structures in which the higher-temperature structures involve a periodic stacking of paramagnetic \\{001\\} planes alternating with magnetically ordered \\{001\\} planes of [001]-moment alignment. In this paper we show that such a coexistence of paramagnetic and magnetically ordered Ce3+ sites can be understood on the basis of the hybridization-mediated interionic interaction when there are cubic crystal-field (CF) interactions of comparable strength. The tendency to form paramagnetic planes is found to increase with increasing CF strength (Γ7 ground state); and the stability of the up-down paramagnetic plane arrangement at high temperatures is shown to arise from the reconciliation of the magnetic ordering with the CF interactions. We also find that for a certain range of parameters a different novel situation occurs, with a fully nonmagnetic (singlet) ground state for the Ce3+ ion. This singlet state is not Kondo-like, and occurs in such a way that the system would be expected to fluctuate between two differently polarized states, one of which is the singlet state.