Dissociation rate of bromine diatomics in an argon heat bath

NASA Technical Reports Server (NTRS)

Razner, R.; Hopkins, D.

1973-01-01

The evolution of a collection of 300 K bromine diatomics embedded in a heat bath of argon atoms at 1800 K was studied by computer, and a dissociation-rate constant for the reaction Br2 + BR + Ar yields Br + Ar was determined. Previously published probability distributions for energy and angular momentum transfers in classical three-dimensional Br2-Ar collisions were used in conjunction with a newly developed Monte Carlo scheme for this purpose. Results are compared with experimental shock-tube data and the predictions of several other theoretical models. A departure from equilibrium is obtained which is significantly greater than that predicted by any of these other theories.

Local-area simulations of rotating compressible convection and associated mean flows

NASA Technical Reports Server (NTRS)

Hurlburt, Neal E.; Brummell, N. H.; Toomre, Juri

1995-01-01

The dynamics of compressible convection within a curved local segment of a rotating spherical shell are considered in relation to the turbulent redistribution of angular momentum within the solar convection zone. Current supercomputers permit fully turbulent flows to be considered within the restricted geometry of local area models. By considering motions in a curvilinear geometry in which the Coriolos parameters vary with latitude, Rossby waves which couple with the turbulent convection are thought of as being possible. Simulations of rotating convection are presented in such a curved local segment of a spherical shell using a newly developed, sixth-order accurate code based on compact finite differences.

Experimental light scattering by ultrasonically controlled small particles - Implications for Planetary Science

NASA Astrophysics Data System (ADS)

Gritsevich, M.; Penttilä, A.; Maconi, G.; Kassamakov, I.; Markkanen, J.; Martikainen, J.; Väisänen, T.; Helander, P.; Puranen, T.; Salmi, A.; Hæggström, E.; Muinonen, K.

2017-09-01

We present the results obtained with our newly developed 3D scatterometer - a setup for precise multi-angular measurements of light scattered by mm- to µm-sized samples held in place by sound. These measurements are cross-validated against the modeled light-scattering characteristics of the sample, i.e., the intensity and the degree of linear polarization of the reflected light, calculated with state-of-the-art electromagnetic techniques. We demonstrate a unique non-destructive approach to derive the optical properties of small grain samples which facilitates research on highly valuable planetary materials, such as samples returned from space missions or rare meteorites.

A new possible picture of the hadron structure

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

Pokrovsky, Yury E.

A new chiral-scale invariant version of the bag model (CSB) is developed and applied to calculations of masses and radii for single bag states. The mass formula of the CSB model contains no free parameters and connects masses and radii of the bags with fundamental QCD scales, namely with {lambda}{sub QCD}, , , and quark masses. For high angular momentum states the CSB model well describes hadron Regge trajectories and predicts thin flux tubes with R{sub tube}{approx_equal}0.25 fm close to the small tube radii introduced a posteriori in modern models. For low angular momentum states this model predicts smallmore » radii of the bags R{sub bag}{approx_equal}0.25 fm close to the radii associated with constituent quarks. Masses of the lowest angular momentum bags are obtained close to the data for well known hadron resonances ({pi}(1300), {omega}(1420), N(1440),{delta}(1600), etc.). These resonances are predicted to be almost single bag states. But ground states of SU(3) hadrons (N(940), {pi}(140), etc.) are treated as strongly bounded multi bag states--BagBag-mesons, and BagBagBag-baryons like in the old Fermi, Yang, and Sakata models. As well, this model predicts the low mass excitations of SU(3) hadrons newly observed for nucleons at the following masses 1004, 1044, and 1094 MeV.« less

An iPhone application for upper arm posture and movement measurements.

PubMed

Yang, Liyun; Grooten, Wilhelmus J A; Forsman, Mikael

2017-11-01

There is a need for objective methods for upper arm elevation measurements for accurate and convenient risk assessments. The aims of this study were (i) to compare a newly developed iOS application (iOS) for measuring upper arm elevation and angular velocity with a reference optical tracking system (OTS), and (ii) to compare the accuracy of the iOS incorporating a gyroscope and an accelerometer with using only an accelerometer, which is standard for inclinometry. The iOS-OTS limits of agreement for static postures (9 subjects) were -4.6° and 4.8°. All root mean square differences in arm swings and two simulated work tasks were <6.0°, and all mean correlation coefficients were >0.98. The mean absolute iOS-OTS difference of median angular velocity was <13.1°/s, which was significantly lower than only using an accelerometer (<43.5°/s). The accuracy of this iOS application compares well to that of today's research methods and it can be useful for practical upper arm measurements. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Automated retinal nerve fiber layer defect detection using fundus imaging in glaucoma.

PubMed

Panda, Rashmi; Puhan, N B; Rao, Aparna; Padhy, Debananda; Panda, Ganapati

2018-06-01

Retinal nerve fiber layer defect (RNFLD) provides an early objective evidence of structural changes in glaucoma. RNFLD detection is currently carried out using imaging modalities like OCT and GDx which are expensive for routine practice. In this regard, we propose a novel automatic method for RNFLD detection and angular width quantification using cost effective redfree fundus images to be practically useful for computer-assisted glaucoma risk assessment. After blood vessel inpainting and CLAHE based contrast enhancement, the initial boundary pixels are identified by local minima analysis of the 1-D intensity profiles on concentric circles. The true boundary pixels are classified using random forest trained by newly proposed cumulative zero count local binary pattern (CZC-LBP) and directional differential energy (DDE) along with Shannon, Tsallis entropy and intensity features. Finally, the RNFLD angular width is obtained by random sample consensus (RANSAC) line fitting on the detected set of boundary pixels. The proposed method is found to achieve high RNFLD detection performance on a newly created dataset with sensitivity (SN) of 0.7821 at 0.2727 false positives per image (FPI) and the area under curve (AUC) value is obtained as 0.8733. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Real-Time Imaging System for Stereo Atomic Microscopy at SPring-8's BL25SU

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

Matsushita, Tomohiro; Guo, Fang Zhun; Muro, Takayuki

2007-01-19

We have developed a real-time photoelectron angular distribution (PEAD) and Auger-electron angular distribution (AEAD) imaging system at SPring-8 BL25SU, Japan. In addition, a real-time imaging system for circular dichroism (CD) studies of PEAD/AEAD has been newly developed. Two PEAD images recorded with left- and right-circularly polarized light can be regarded as a stereo image of the atomic arrangement. A two-dimensional display type mirror analyzer (DIANA) has been installed at the beamline, making it possible to record PEAD/AEAD patterns with an acceptance angle of {+-}60 deg. in real-time. The twin-helical undulators at BL25SU enable helicity switching of the circularly polarized lightmore » at 10Hz, 1Hz or 0.1Hz. In order to realize real-time measurements of the CD of the PEAD/AEAD, the CCD camera must be synchronized to the switching frequency. The VME computer that controls the ID is connected to the measurement computer with two BNC cables, and the helicity information is sent using TTL signals. For maximum flexibility, rather than using a hardware shutter synchronizing with the TTL signal we have developed software to synchronize the CCD shutter with the TTL signal. We have succeeded in synchronizing the CCD camera in both the 1Hz and 0.1Hz modes.« less

Measurement of lengths and angles by means of a photoelectric direct reading-off microscope

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

Priver, L.S.

1995-11-01

We consider the measurement of lengths and angles over a broad range with error amounting to fractions of a micrometer or angular second using a newly designed mockup of a photoelectric direct reading-off microscope. The microscope implements a pulse-position method of transforming information through application of a scanner in the form of a rotating polyhedral mirror.

Accurate integration over atomic regions bounded by zero-flux surfaces.

PubMed

Polestshuk, Pavel M

2013-01-30

The approach for the integration over a region covered by zero-flux surface is described. This approach based on the surface triangulation technique is efficiently realized in a newly developed program TWOE. The elaborated method is tested on several atomic properties including the source function. TWOE results are compared with those produced by using well-known existing programs. Absolute errors in computed atomic properties are shown to range usually from 10(-6) to 10(-5) au. The demonstrative examples prove that present realization has perfect convergence of atomic properties with increasing size of angular grid and allows to obtain highly accurate data even in the most difficult cases. It is believed that the developed program can be bridgehead that allows to implement atomic partitioning of any desired molecular property with high accuracy. Copyright © 2012 Wiley Periodicals, Inc.

Collapse of magnetized hypermassive neutron stars in general relativity.

PubMed

Duez, Matthew D; Liu, Yuk Tung; Shapiro, Stuart L; Shibata, Masaru; Stephens, Branson C

2006-01-27

Hypermassive neutron stars (HMNSs)--equilibrium configurations supported against collapse by rapid differential rotation--are possible transient remnants of binary neutron-star mergers. Using newly developed codes for magnetohydrodynamic simulations in dynamical spacetimes, we are able to track the evolution of a magnetized HMNS in full general relativity for the first time. We find that secular angular momentum transport due to magnetic braking and the magnetorotational instability results in the collapse of an HMNS to a rotating black hole, accompanied by a gravitational wave burst. The nascent black hole is surrounded by a hot, massive torus undergoing quasistationary accretion and a collimated magnetic field. This scenario suggests that HMNS collapse is a possible candidate for the central engine of short gamma-ray bursts.

A comprehensive experimental characterization of the iPIX gamma imager

NASA Astrophysics Data System (ADS)

Amgarou, K.; Paradiso, V.; Patoz, A.; Bonnet, F.; Handley, J.; Couturier, P.; Becker, F.; Menaa, N.

2016-08-01

The results of more than 280 different experiments aimed at exploring the main features and performances of a newly developed gamma imager, called iPIX, are summarized in this paper. iPIX is designed to quickly localize radioactive sources while estimating the ambient dose equivalent rate at the measurement point. It integrates a 1 mm thick CdTe detector directly bump-bonded to a Timepix chip, a tungsten coded-aperture mask, and a mini RGB camera. It also represents a major technological breakthrough in terms of lightness, compactness, usability, response sensitivity, and angular resolution. As an example of its key strengths, an 241Am source with a dose rate of only few nSv/h can be localized in less than one minute.

Determination of the SNPP VIIRS SDSM Screen Relative Transmittance From Both Yaw Maneuver and Regular On-Orbit Data

NASA Technical Reports Server (NTRS)

Lei, Ning; Chen, Xuexia; Xiong, Xiaoxiong

2015-01-01

The Visible Infrared Imaging Radiometer Suiteaboard the Suomi National Polar-orbiting Partnership (SNPP) satellite performs radiometric calibration of its reflective solar bands primarily through observing a sunlit onboard solar diffuser (SD). The SD bidirectional reflectance distribution function(BRDF) degradation factor is determined by an onboard SD stability monitor (SDSM), which observes the Sun through a pinhole screen and the sunlit SD. The transmittance of the SDSM pinhole screen over a range of solar angles was determined prelaunch and used initially to determine the BRDF degradation factor.The degradation-factor-versus-time curves were found to have a number of very large unphysical undulations likely due to the inaccuracy in the prelaunch determined SDSM screen transmittance.To refine the SDSM screen transmittance, satellite yaw maneuvers were carried out. With the SDSM screen relative transmittance determined from the yaw maneuver data, the computed BRDFdegradation factor curves still have large unphysical ripples, indicating that the projected solar horizontal angular step size in the yaw maneuver data is too large to resolve the transmittance at a fine angular scale. We develop a methodology to use both the yaw maneuver and a small portion of regular on-orbit data to determine the SDSM screen relative transmittance at a fine angular scale. We determine that the error standard deviation of the calculated relative transmittance ranges from 0.00030 (672 nm) to 0.00092 (926 nm). With the newly determined SDSM screen relative transmittance, the computed BRDF degradation factor behaves much more smoothly over time.

An impact rotary motor based on a fiber torsional piezoelectric actuator

NASA Astrophysics Data System (ADS)

Han, W. X.; Zhang, Q.; Ma, Y. T.; Pan, C. L.; Feng, Z. H.

2009-01-01

A prototype small impact rotary motor has been fabricated based on a newly developed torsional actuator which is 15.0 mm long and 1.0 mm in diameter. The motor can rotate when it is powered with a saw-shaped voltage. The experimental results show that its angular speed is proportional to both the driving voltage's amplitude and the frequency under 1 kHz. The large nonlinearity occurs at higher driving frequency due to the resonance of the partial mechanical structure of the motor. The motor can rotate at a speed of 90 rpm with a saw-shaped driving voltage of 600Vp.-p. at 8 kHz, and produce a stall torque of 80 μN m with 1000Vp.-p. at 3 kHz.

Influence of induced colour centres on the frequency - angular spectrum of a light bullet of mid-IR radiation in lithium fluoride

NASA Astrophysics Data System (ADS)

Chekalin, S. V.; Kompanets, V. O.; Dormidonov, A. E.; Kandidov, V. P.

2017-04-01

The influence of the occurrence of a structure consisting of long-lived colour centres, formed in an LiF crystal upon filamentation of femtosecond mid-IR radiation, on the supercontinuum characteristics is investigated. With an increase in the number of incident pulses, the length and transverse size of the structure of colour centres induced in LiF increase, and the supercontinuum spectrum in the short-wavelength region is markedly transformed due to the occurrence of the waveguide propagation regime, absorption, and scattering of radiation from the newly formed structure of colour centres. Under these conditions, the intensity of the anti-Stokes wing decreases by two orders of magnitude after several tens of pulses. Spectral components arise in the visible range, the angular divergence of which increases with increasing wavelength.

A new method for recognizing quadric surfaces from range data and its application to telerobotics and automation, final phase

NASA Technical Reports Server (NTRS)

Mielke, Roland; Dcunha, Ivan; Alvertos, Nicolas

1994-01-01

In the final phase of the proposed research a complete top to down three dimensional object recognition scheme has been proposed. The various three dimensional objects included spheres, cones, cylinders, ellipsoids, paraboloids, and hyperboloids. Utilizing a newly developed blob determination technique, a given range scene with several non-cluttered quadric surfaces is segmented. Next, using the earlier (phase 1) developed alignment scheme, each of the segmented objects are then aligned in a desired coordinate system. For each of the quadric surfaces based upon their intersections with certain pre-determined planes, a set of distinct features (curves) are obtained. A database with entities such as the equations of the planes and angular bounds of these planes has been created for each of the quadric surfaces. Real range data of spheres, cones, cylinders, and parallelpipeds have been utilized for the recognition process. The developed algorithm gave excellent results for the real data as well as for several sets of simulated range data.

The erethizontid fossil from the Uquía formation of Argentina should not be referred to the genus Erethizon

NASA Astrophysics Data System (ADS)

Sussman, David R.

2011-04-01

In 2007, Reguero et al. described a 2.5 Ma erethizontid dentary from the Uquía Formation in Argentina (MACN5376) and referred it to the genus Erethizon, a genus found at present only in North America. They based their generic identification on the presence in the fossil of a markedly inflected angular process. I argue in this commentary that this single trait (the angular process) in a single incomplete fossil is insufficient evidence for the Erethizon attribution, for the following reasons: 1. The trait (the inflected angular process) is variable in modern South and North American porcupines and observer bias and/or allometry may be responsible for observed differences; 2. Among fossil South American porcupines, the inflected angular process is not unique to the Uquían fossil; 3. The fossil possesses other traits (including one trait newly described in this paper) associated with modern South American ( Coendou) porcupines and not modern Erethizon; and 4. The traits by which we recognize modern Erethizon, primarily related to the genus's ability to survive severe winters, are most readily explained by evolution driven by the South American porcupine immigrants' exposure in North America to that severe weather. The Uquían fossil is not Erethizon and should be attributed for the present to the genus Coendou.

The Spin Evolution of Fast-rotating, Magnetized Super-Chandrasekhar White Dwarfs in the Aftermath of White Dwarf Mergers

NASA Astrophysics Data System (ADS)

Becerra, L.; Rueda, J. A.; Lorén-Aguilar, P.; García-Berro, E.

2018-04-01

The evolution of the remnant of the merger of two white dwarfs is still an open problem. Furthermore, few studies have addressed the case in which the remnant is a magnetic white dwarf with a mass larger than the Chandrasekhar limiting mass. Angular momentum losses might bring the remnant of the merger to the physical conditions suitable for developing a thermonuclear explosion. Alternatively, the remnant may be prone to gravitational or rotational instabilities, depending on the initial conditions reached after the coalescence. Dipole magnetic braking is one of the mechanisms that can drive such losses of angular momentum. However, the timescale on which these losses occur depends on several parameters, like the strength of the magnetic field. In addition, the coalescence leaves a surrounding Keplerian disk that can be accreted by the newly formed white dwarf. Here we compute the post-merger evolution of a super-Chandrasekhar magnetized white dwarf taking into account all the relevant physical processes. These include magnetic torques acting on the star, accretion from the Keplerian disk, the threading of the magnetic field lines through the disk, and the thermal evolution of the white dwarf core. We find that the central remnant can reach the conditions suitable to develop a thermonuclear explosion before other instabilities (such as the inverse beta-decay instability or the secular axisymmetric instability) are reached, which would instead lead to gravitational collapse of the magnetized remnant.

Linear- and angular-shaped naphthodithiophenes: selective synthesis, properties, and application to organic field-effect transistors.

PubMed

Shinamura, Shoji; Osaka, Itaru; Miyazaki, Eigo; Nakao, Akiko; Yamagishi, Masakazu; Takeya, Jun; Takimiya, Kazuo

2011-04-06

A straightforward synthetic approach that exploits linear- and angular-shaped naphthodithiophenes (NDTs) being potential as new core structures for organic semiconductors is described. The newly established synthetic procedure involves two important steps; one is the chemoselective Sonogashira coupling reaction on the trifluoromethanesulfonyloxy site over the bromine site enabling selective formation of o-bromoethynylbenzene substructures on the naphthalene core, and the other is a facile ring closing reaction of fused-thiophene rings from the o-bromoethynylbenzene substructures. As a result, three isomeric NDTs, naphtho[2,3-b:6,7-b']dithiophene, naphtho[2,3-b:7,6-b']dithiophenes, and naphtho[2,1-b:6,5-b']dithiophene, are selectively synthesized. Electrochemical and optical measurements of the parent NDTs indicated that the shape of the molecules plays an important role in determining the electronic structure of the compounds; the linear-shaped NDTs formally isoelectronic with naphthacene have lower oxidation potentials and more red-shifted absorption bands than those of the angular-shaped NDTs isoelectronic with chrysene. On the contrary, the performance of the thin-film-based field-effect transistors (FETs) using the dioctyl or diphenyl derivatives were much influenced by the symmetry of the molecules; centrosymmetric derivatives tend to give higher mobility (up to 1.5 cm(2) V(-1) s(-1)) than axisymmetric ones (∼0.06 cm(2) V(-1) s(-1)), implying that the intermolecular orbital overlap in the solid state is influenced by the symmetry of the molecules. These results indicate that the present NDT cores, in particular the linear-shaped, centrosymmetric naphtho[2,3-b:6,7-b']dithiophene, are promising building blocks for the development of organic semiconducting materials. © 2011 American Chemical Society

Exploiting OSPaN (Optical Solar Patrol Network) Data to Understand Large-Scale Solar Eruptions Impacting Space Weather

DTIC Science & Technology

2011-12-28

shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number...by CMEs; (2) the angular orientation of newly emerged magnetic flux on the solar surface relative to stable filaments plays a role in how rapidly the...potential of exploiting ISOON observations to increase our understanding of solar eruptions, a requirement for improved prediction and mitigation of space

Quadratic Finite Element Method for 1D Deterministic Transport

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

Tolar, Jr., D R; Ferguson, J M

2004-01-06

In the discrete ordinates, or SN, numerical solution of the transport equation, both the spatial ({und r}) and angular ({und {Omega}}) dependences on the angular flux {psi}{und r},{und {Omega}}are modeled discretely. While significant effort has been devoted toward improving the spatial discretization of the angular flux, we focus on improving the angular discretization of {psi}{und r},{und {Omega}}. Specifically, we employ a Petrov-Galerkin quadratic finite element approximation for the differencing of the angular variable ({mu}) in developing the one-dimensional (1D) spherical geometry S{sub N} equations. We develop an algorithm that shows faster convergence with angular resolution than conventional S{sub N} algorithms.

An integrated platform for biomolecule interaction analysis

NASA Astrophysics Data System (ADS)

Jan, Chia-Ming; Tsai, Pei-I.; Chou, Shin-Ting; Lee, Shu-Sheng; Lee, Chih-Kung

2013-02-01

We developed a new metrology platform which can detect real-time changes in both a phase-interrogation mode and intensity mode of a SPR (surface plasmon resonance). We integrated a SPR and ellipsometer to a biosensor chip platform to create a new biomolecular interaction measurement mechanism. We adopted a conductive ITO (indium-tinoxide) film to the bio-sensor platform chip to expand the dynamic range and improve measurement accuracy. The thickness of the conductive film and the suitable voltage constants were found to enhance performance. A circularly polarized ellipsometry configuration was incorporated into the newly developed platform to measure the label-free interactions of recombinant human C-reactive protein (CRP) with immobilized biomolecule target monoclonal human CRP antibody at various concentrations. CRP was chosen as it is a cardiovascular risk biomarker and is an acute phase reactant as well as a specific prognostic indicator for inflammation. We found that the sensitivity of a phaseinterrogation SPR is predominantly dependent on the optimization of the sample incidence angle. The effect of the ITO layer effective index under DC and AC effects as well as an optimal modulation were experimentally performed and discussed. Our experimental results showed that the modulated dynamic range for phase detection was 10E-2 RIU based on a current effect and 10E-4 RIU based on a potential effect of which a 0.55 (°/RIU) measurement was found by angular-interrogation. The performance of our newly developed metrology platform was characterized to have a higher sensitivity and less dynamic range when compared to a traditional full-field measurement system.

Autocollimation system for measuring angular deformations with reflector designed by quaternionic method

NASA Astrophysics Data System (ADS)

Hoang, Phong V.; Konyakhin, Igor A.

2017-06-01

Autocollimators are widely used for angular measurements in instrument-making and the manufacture of elements of optical systems (wedges, prisms, plane-parallel plates) to check their shape parameters (rectilinearity, parallelism and planarity) and retrieve their optical parameters (curvature radii, measure and test their flange focusing). Autocollimator efficiency is due to the high sensitivity of the autocollimation method to minor rotations of the reflecting control element or the controlled surface itself. We consider using quaternions to optimize reflector parameters during autocollimation measurements as compared to the matrix technique. Mathematical model studies have demonstrated that the orthogonal positioning of the two basic unchanged directions of the tetrahedral reflector of the autocollimator is optimal by the criterion of reducing measurement errors where the axis of actual rotation is in a bisecting position towards them. Computer results are presented of running quaternion models that yielded conditions for diminishing measurement errors provided apriori information is available on the position of rotation axis. A practical technique is considered for synthesizing the parameters of the tetrahedral reflector that employs the newly-retrieved relationships. Following the relationships found between the angles of the tetrahedral reflector and the angles of the parameters of its initial orientation, an applied technique was developed to synthesize the control element for autocollimation measurements in case apriori information is available on the axis of actual rotation during monitoring measurements of shaft or pipeline deformation.

High-frequency variations in Earth rotation and the planetary momentum budget

NASA Technical Reports Server (NTRS)

Rosen, Richard D.

1995-01-01

The major focus of the subject contract was on helping to resolve one of the more notable discrepancies still existing in the axial momentum budget of the solid Earth-atmosphere system, namely the disappearance of coherence between length-of-day (l.o.d.) and atmospheric angular momentum (AAM) at periods shorter than about a fortnight. Recognizing the importance of identifying the source of the high-frequency momentum budget anomaly, the scientific community organized two special measurement campaigns (SEARCH '92 and CONT '94) to obtain the best possible determinations of l.o.d. and AAM. An additional goal was to analyze newly developed estimates of the torques that transfer momentum between the atmosphere and its underlying surface to determine whether the ocean might be a reservoir of momentum on short time scales. Discrepancies between AAM and l.o.d. at sub-fortnightly periods have been attributed to either measurement errors in these quantities or the need to incorporate oceanic angular momentum into the planetary budget. Results from the SEARCH '92 and CONT '94 campaigns suggest that when special attention is paid to the quality of the measurements, better agreement between l.o.d. and AAM at high frequencies can be obtained. The mechanism most responsible for the high-frequency changes observed in AAM during these campaigns involves a direct coupling to the solid Earth, i.e, the mountain torque, thereby obviating a significant oceanic role.

Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

NASA Technical Reports Server (NTRS)

Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

2010-01-01

The future X-ray observatory missions, such as International X-ray Observatory, require grazing incidence replicated optics of extremely large collecting area (3 m2) in combination with angular resolution of less than 5 arcsec half-power diameter. The resolution of a mirror shell depends ultimately on the quality of the cylindrical mandrels from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation studies have been performed to optimize the operational parameters as well as the polishing lap configuration. Furthermore, depending upon the surface error profile, a model for localized polishing based on dwell time approach is developed. Using the inputs from the mathematical model, a mandrel, having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. We report our first experimental results and discuss plans for further improvements in the polishing process.

Investigation of application of two-degree-of-freedom dry tuned-gimbal gyroscopes to strapdown navigation systems. [for use in VTOL aircraft

NASA Technical Reports Server (NTRS)

1974-01-01

The work is described which was accomplished during the investigation of the application of dry-tuned gimbal gyroscopes to strapdown navigation systems. A conventional strapdown configuration, employing analog electronics in conjunction with digital attitude and navigation computation, was examined using various levels of redundancy and both orthogonal and nonorthogonal sensor orientations. It is concluded that the cost and reliability performance constraints which had been established could not be met simultaneously with such a system. This conclusion led to the examination of an alternative system configuration which utilizes an essentially new strapdown system concept. This system employs all-digital signal processing in conjunction with the newly-developed large scale integration (LSI) electronic packaging techniques and a new two-degree-of-freedom dry tuned-gimbal instrument which is capable of providing both angular rate and acceleration information. Such a system is capable of exceeding the established performance goals.

Long-term monitoring of Sgr A* at 7 mm with VERA and KaVA

NASA Astrophysics Data System (ADS)

Akiyama, K.; Kino, M.; Sohn, B.; Lee, S.; Trippe, S.; Honma, M.

2014-05-01

We present the results of radio monitoring observations of Sgr A* at 7 mm (i.e. 43 GHz) with the VLBI Exploration of Radio Astrometry (VERA), which is a VLBI array in Japan. VERA provides angular resolution on millisecond scales, resolving structures within 100 Schwarzschild radii of Sgr A* , similar to the Very Large Baseline Array (VLBA). We performed multi-epoch observations of Sgr A* in 2005 - 2008, and started monitoring it again with VERA from 2013 January to trace the current G2 encounter event. Our preliminary results in 2013 show that Sgr A* on mas scales has been in an ordinary state as of August 2013, although some fraction of the G2 cloud already passed the pericenter of Sgr A* in April 2013. We will continue monitoring Sgr A* with VERA and the newly developed KaVA (KVN and VERA Array).

Test of mutually unbiased bases for six-dimensional photonic quantum systems

PubMed Central

D'Ambrosio, Vincenzo; Cardano, Filippo; Karimi, Ebrahim; Nagali, Eleonora; Santamato, Enrico; Marrucci, Lorenzo; Sciarrino, Fabio

2013-01-01

In quantum information, complementarity of quantum mechanical observables plays a key role. The eigenstates of two complementary observables form a pair of mutually unbiased bases (MUBs). More generally, a set of MUBs consists of bases that are all pairwise unbiased. Except for specific dimensions of the Hilbert space, the maximal sets of MUBs are unknown in general. Even for a dimension as low as six, the identification of a maximal set of MUBs remains an open problem, although there is strong numerical evidence that no more than three simultaneous MUBs do exist. Here, by exploiting a newly developed holographic technique, we implement and test different sets of three MUBs for a single photon six-dimensional quantum state (a “qusix”), encoded exploiting polarization and orbital angular momentum of photons. A close agreement is observed between theory and experiments. Our results can find applications in state tomography, quantitative wave-particle duality, quantum key distribution. PMID:24067548

Test of mutually unbiased bases for six-dimensional photonic quantum systems.

PubMed

D'Ambrosio, Vincenzo; Cardano, Filippo; Karimi, Ebrahim; Nagali, Eleonora; Santamato, Enrico; Marrucci, Lorenzo; Sciarrino, Fabio

2013-09-25

In quantum information, complementarity of quantum mechanical observables plays a key role. The eigenstates of two complementary observables form a pair of mutually unbiased bases (MUBs). More generally, a set of MUBs consists of bases that are all pairwise unbiased. Except for specific dimensions of the Hilbert space, the maximal sets of MUBs are unknown in general. Even for a dimension as low as six, the identification of a maximal set of MUBs remains an open problem, although there is strong numerical evidence that no more than three simultaneous MUBs do exist. Here, by exploiting a newly developed holographic technique, we implement and test different sets of three MUBs for a single photon six-dimensional quantum state (a "qusix"), encoded exploiting polarization and orbital angular momentum of photons. A close agreement is observed between theory and experiments. Our results can find applications in state tomography, quantitative wave-particle duality, quantum key distribution.

Viscoelastic Properties and Morphology of Mumio-based Medicated Hydrogels

NASA Astrophysics Data System (ADS)

Zandraa, Oyunchimeg; Jelínková, Lenka; Roy, Niladri; Sáha, Tomáš; Kitano, Takeshi; Saha, Nabanita

2011-07-01

Novel medicated hydrogels were prepared (by moist heat treatment) with PVA, agar, mumio, mare's milk (MM), seabuckthorn oil (SB oil) and salicylic acid (SA) for wound dressing/healing application. Scanning electron micrographs (SEM) show highly porous structure of these hydrogels. The swelling behaviour of the hydrogels in physiological solution displays remarkable liquid absorption property. The knowledge obtained from rheological investigations of these-systems may be highly useful for the characterization of the newly developed topical formulations. In the present study, an oscillation frequency sweep test was used for the evaluation of storage modulus (G'), loss modulus (G″), and complex viscosity (η*) of five different formulations, over an angular frequency range from 0.1 to 100 rad.s-1. The influence of healing agents and swelling effect on the rheological properties of mumio-based medicated hydrogels was investigated to judge its application on uneven surface of body.

The energy spectrum and geometrical structure of Galactic turbulent magnetic field

NASA Astrophysics Data System (ADS)

Sun, Xiaohui; Gaensler, Bryan; Mcclure-Griffiths, Naomi; Purcell, Cormac; Hill, Alex; Burkhart, Blakesley; Lazarian, Alex

2012-10-01

The energy spectrum and geometrical structure of the turbulent magnetic field can offer a solid test of different theoretical models on the generation and evolution of Galactic magnetic fields. They are also pivotal to understanding the propagation of cosmic-ray particles. However, the energy spectrum has been difficult to determine and the geometrical structure has never been obtained so far, due to lack of proper methods and observations. We aim to infer these quantities by applying our newly developed techniques to polarisation images. These images are required to be observed with high angular resolution and broadband multi-channel polarimetry, which is possible only recently using the ATCA. As a pilot study, we plan to map the 2X2 degree high-latitude field centred at l=255.5 degree and b=-38 degree at 1.1-3.1 GHz in total intensity and polarisation.

The energy spectrum and geometrical structure of Galactic turbulent magnetic field

NASA Astrophysics Data System (ADS)

Sun, Xiaohui; Gaensler, Bryan; Mcclure-Griffiths, Naomi; Purcell, Cormac; Hill, Alex; Burkhart, Blakesley; Lazarian, Alex

2012-04-01

The energy spectrum and geometrical structure of the turbulent magnetic field can offer a solid test of different theoretical models on the generation and evolution of Galactic magnetic fields. They are also pivotal to understanding the propagation of cosmic-ray particles. However, the energy spectrum has been difficult to determine and the geometrical structure has never been obtained so far, due to lack of proper methods and observations. We aim to infer these quantities by applying our newly developed techniques to polarisation images. These images are required to be observed with high angular resolution and broadband multi-channel polarimetry, which is possible only recently using the ATCA. As a pilot study, we plan to map the 2X2 degree high-latitude field centred at l=255.5 degree and b=-38 degree at 1.1-3.1 GHz in total intensity and polarisation.

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

Sengupta, M.; Ganesh, R.

The dynamics of cylindrically trapped electron plasma has been investigated using a newly developed 2D Electrostatic PIC code that uses unapproximated, mass-included equations of motion for simulation. Exhaustive simulations, covering the entire range of Brillouin ratio, were performed for uniformly filled circular profiles in rigid rotor equilibrium. The same profiles were then loaded away from equilibrium with an initial value of rigid rotation frequency different from that required for radial force balance. Both these sets of simulations were performed for an initial zero-temperature or cold load of the plasma with no spread in either angular velocity or radial velocity. Themore » evolution of the off-equilibrium initial conditions to a steady state involve radial breathing of the profile that scales in amplitude and algebraic growth with Brillouin fraction. For higher Brillouin fractions, the growth of the breathing mode is followed by complex dynamics of spontaneous hollow density structures, excitation of poloidal modes, leading to a monotonically falling density profile.« less

Integrating single-point vibrometer and full-field electronic speckle pattern interferometer to evaluate a micro-speaker

NASA Astrophysics Data System (ADS)

Chang, Wen-Chi; Chen, Yu-Chi; Chien, Chih-Jen; Wang, An-Bang; Lee, Chih-Kung

2011-04-01

A testing system contains an advanced vibrometer/interferometer device (AVID) and a high-speed electronic speckle pattern interferometer (ESPI) was developed. AVID is a laser Doppler vibrometer that can be used to detect single-point linear and angular velocity with DC to 20 MHz bandwidth and with nanometer resolution. In swept frequency mode, frequency response from mHz to MHz of the structure of interest can be measured. The ESPI experimental setup can be used to measure full-field out-of-plane displacement. A 5-1 phase shifting method and a correlation algorithm were used to analyze the phase difference between the reference signal and the speckle signal scattered from the sample surface. In order to show the efficiency and effectiveness of AVID and ESPI, we designed a micro-speaker composed of a plate with fixed boundaries and two piezo-actuators attached to the sides of the plate. The AVID was used to measure the vibration of one of the piezo-actuators and the ESPI was adopted to measure the two-dimensional out-of-plane displacement of the plate. A microphone was used to measure the acoustic response created by the micro-speaker. Driving signal includes random signal, sinusoidal signal, amplitude modulated high-frequency carrier signal, etc. Angular response induced by amplitude modulated high-frequency carrier signal was found to be significantly narrower than the frequency responses created by other types of driving signals. The validity of our newly developed NDE system are detailed by comparing the relationship between the vibration signal of the micro-speaker and the acoustic field generated.

Rotational broadening and conservation of angular momentum in post-extreme horizontal branch stars

NASA Astrophysics Data System (ADS)

Fontaine, G.; Latour, M.

2018-06-01

We show that the recent realization that isolated post-extreme horizontal branch (post-EHB) stars are generally characterized by rotational broadening with values of V rot sini between 25 and 30 km s-1 can be explained as a natural consequence of the conservation of angular momentum from the previous He-core burning phase on the EHB. The progenitors of these evolved objects, the EHB stars, are known to be slow rotators with an average value of V rot sini of 7.7 km s-1. This implies significant spin-up between the EHB and post-EHB phases. Using representative evolutionary models of hot subdwarf stars, we demonstrate that angular momentum conservation in uniformly rotating structures (rigid-body rotation) boosts that value of the projected equatorial rotation speed by a factor 3.6 by the time the model has reached the region of the surface gravity-effective temperature plane where the newly-studied post-EHB objects are found. This is exactly what is needed to account for their observed atmospheric broadening. We note that the decrease of the moment of inertia causing the spin-up is mostly due to the redistribution of matter that produces more centrally-condensed structures in the post-EHB phase of evolution, not to the decrease of the radius per se.

Characterization of Diesel Soot Aggregates by Scattering and Extinction Methods

NASA Astrophysics Data System (ADS)

Kamimoto, Takeyuki

2006-07-01

Characteristics of diesel soot particles sampled from diesel exhaust of a common-rail turbo-charged diesel engine are quantified by scattering and extinction diagnostics using newly build two laser-based instruments. The radius of gyration representing the aggregates size is measured by the angular distribution of scattering intensity, while the soot mass concentration is measured by a two-wavelength extinction method. An approach to estimate the refractive index of diesel soot by an analysis of the extinction and scattering data using an aggregates scattering theory is proposed.

Prediction of Lunar Reconnaissance Orbiter Reaction Wheel Assembly Angular Momentum Using Regression Analysis

NASA Technical Reports Server (NTRS)

DeHart, Russell

2017-01-01

This study determines the feasibility of creating a tool that can accurately predict Lunar Reconnaissance Orbiter (LRO) reaction wheel assembly (RWA) angular momentum, weeks or even months into the future. LRO is a three-axis stabilized spacecraft that was launched on June 18, 2009. While typically nadir-pointing, LRO conducts many types of slews to enable novel science collection. Momentum unloads have historically been performed approximately once every two weeks with the goal of maintaining system total angular momentum below 70 Nms; however flight experience shows the models developed before launch are overly conservative, with many momentum unloads being performed before system angular momentum surpasses 50 Nms. A more accurate model of RWA angular momentum growth would improve momentum unload scheduling and decrease the frequency of these unloads. Since some LRO instruments must be deactivated during momentum unloads and in the case of one instrument, decontaminated for 24 hours there after a decrease in the frequency of unloads increases science collection. This study develops a new model to predict LRO RWA angular momentum. Regression analysis of data from October 2014 to October 2015 was used to develop relationships between solar beta angle, slew specifications, and RWA angular momentum growth. The resulting model predicts RWA angular momentum using input solar beta angle and mission schedule data. This model was used to predict RWA angular momentum from October 2013 to October 2014. Predictions agree well with telemetry; of the 23 momentum unloads performed from October 2013 to October 2014, the mean and median magnitude of the RWA total angular momentum prediction error at the time of the momentum unloads were 3.7 and 2.7 Nms, respectively. The magnitude of the largest RWA total angular momentum prediction error was 10.6 Nms. Development of a tool that uses the models presented herein is currently underway.

Stern-Gerlach-like approach to electron orbital angular momentum measurement

DOE PAGES

Harvey, Tyler R.; Grillo, Vincenzo; McMorran, Benjamin J.

2017-02-28

Many methods now exist to prepare free electrons into orbital-angular-momentum states, and the predicted applications of these electron states as probes of materials and scattering processes are numerous. The development of electron orbital-angular-momentum measurement techniques has lagged behind. We show that coupling between electron orbital angular momentum and a spatially varying magnetic field produces an angular-momentum-dependent focusing effect. We propose a design for an orbital-angular-momentum measurement device built on this principle. As the method of measurement is noninterferometric, the device works equally well for mixed, superposed, and pure final orbital-angular-momentum states. The energy and orbital-angular-momentum distributions of inelastically scattered electronsmore » may be simultaneously measurable with this technique.« less

Stern-Gerlach-like approach to electron orbital angular momentum measurement

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

Harvey, Tyler R.; Grillo, Vincenzo; McMorran, Benjamin J.

Many methods now exist to prepare free electrons into orbital-angular-momentum states, and the predicted applications of these electron states as probes of materials and scattering processes are numerous. The development of electron orbital-angular-momentum measurement techniques has lagged behind. We show that coupling between electron orbital angular momentum and a spatially varying magnetic field produces an angular-momentum-dependent focusing effect. We propose a design for an orbital-angular-momentum measurement device built on this principle. As the method of measurement is noninterferometric, the device works equally well for mixed, superposed, and pure final orbital-angular-momentum states. The energy and orbital-angular-momentum distributions of inelastically scattered electronsmore » may be simultaneously measurable with this technique.« less

Planet Formation in Disks with Inclined Binary Companions: Can Primordial Spin-Orbit Misalignment be Produced?

NASA Astrophysics Data System (ADS)

Zanazzi, J. J.; Lai, Dong

2018-04-01

Many hot Jupiter (HJ) systems have been observed to have their stellar spin axis misaligned with the planet's orbital angular momentum axis. The origin of this spin-orbit misalignment and the formation mechanism of HJs remain poorly understood. A number of recent works have suggested that gravitational interactions between host stars, protoplanetary disks, and inclined binary companions may tilt the stellar spin axis with respect to the disk's angular angular momentum axis, producing planetary systems with misaligned orbits. These previous works considered idealized disk evolution models and neglected the gravitational influence of newly formed planets. In this paper, we explore how disk photoevaporation and planet formation and migration affect the inclination evolution of planet-star-disk-binary systems. We take into account planet-disk interactions and the gravitational spin-orbit coupling between the host star and the planet. We find that the rapid depletion of the inner disk via photoevaporation reduces the excitation of stellar obliquities. Depending on the formation and migration history of HJs, the spin-orbit coupling between the star and the planet may reduces and even completely suppress the excitation of stellar obliquities. Our work constrains the formation/migration history of HJs. On the other hand, planetary systems with "cold" Jupiters or close-in super-earths may experience excitation of stellar obliquities in the presence of distant inclined companions.

Planet formation in discs with inclined binary companions: can primordial spin-orbit misalignment be produced?

NASA Astrophysics Data System (ADS)

Zanazzi, J. J.; Lai, Dong

2018-07-01

Many hot Jupiter (HJ) systems have been observed to have their stellar spin axis misaligned with the planet's orbital angular momentum axis. The origin of this spin-orbit misalignment and the formation mechanism of HJs remain poorly understood. A number of recent works have suggested that gravitational interactions between host stars, protoplanetary discs, and inclined binary companions may tilt the stellar spin axis with respect to the disc's angular angular momentum axis, producing planetary systems with misaligned orbits. These previous works considered idealized disc evolution models and neglected the gravitational influence of newly formed planets. In this paper, we explore how disc photoevaporation and planet formation and migration affect the inclination evolution of planet-star-disc-binary systems. We take into account planet-disc interactions and the gravitational spin-orbit coupling between the host star and the planet. We find that the rapid depletion of the inner disc via photoevaporation reduces the excitation of stellar obliquities. Depending on the formation and migration history of HJs, the spin-orbit coupling between the star and the planet may reduces and even completely suppress the excitation of stellar obliquities. Our work constrains the formation/migration history of HJs. On the other hand, planetary systems with `cold' Jupiters or close-in super-earths may experience excitation of stellar obliquities in the presence of distant inclined companions.

THE OPTICS OF REFRACTIVE SUBSTRUCTURE

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

Johnson, Michael D.; Narayan, Ramesh, E-mail: mjohnson@cfa.harvard.edu

2016-08-01

Newly recognized effects of refractive scattering in the ionized interstellar medium have broad implications for very long baseline interferometry (VLBI) at extreme angular resolutions. Building upon work by Blandford and Narayan, we present a simplified, geometrical optics framework, which enables rapid, semi-analytic estimates of refractive scattering effects. We show that these estimates exactly reproduce previous results based on a more rigorous statistical formulation. We then derive new expressions for the scattering-induced fluctuations of VLBI observables such as closure phase, and we demonstrate how to calculate the fluctuations for arbitrary quantities of interest using a Monte Carlo technique.

Statistical prescission point model of fission fragment angular distributions

NASA Astrophysics Data System (ADS)

John, Bency; Kataria, S. K.

1998-03-01

In light of recent developments in fission studies such as slow saddle to scission motion and spin equilibration near the scission point, the theory of fission fragment angular distribution is examined and a new statistical prescission point model is developed. The conditional equilibrium of the collective angular bearing modes at the prescission point, which is guided mainly by their relaxation times and population probabilities, is taken into account in the present model. The present model gives a consistent description of the fragment angular and spin distributions for a wide variety of heavy and light ion induced fission reactions.

Statistical properties of correlated solar flares and coronal mass ejections in cycles 23 and 24

NASA Astrophysics Data System (ADS)

Aarnio, Alicia

2018-01-01

Outstanding problems in understanding early stellar systems include mass loss, angular momentum evolution, and the effects of energetic events on the surrounding environs. The latter of these drives much research into our own system's space weather and the development of predictive algorithms for geomagnetic storms. So dually motivated, we have leveraged a big-data approach to combine two decades of GOES and LASCO data to identify a large sample of spatially and temporally correlated solar flares and CMEs. In this presentation, we revisit the analysis of Aarnio et al. (2011), adding 10 years of data and further exploring the relationships between correlated flare and CME properties. We compare the updated data set results to those previously obtained, and discuss the effects of selecting smaller time windows within solar cycles 23 and 24 on the empirically defined relationships between correlated flare and CME properties. Finally, we discuss a newly identified large sample of potentially interesting correlated flares and CMEs perhaps erroneously excluded from previous searches.

Role of electronic correlations in photoionization of NO2 in the vicinity of the 2A1/2B2 conical intersection.

PubMed

Brambila, Danilo S; Harvey, Alex G; Houfek, Karel; Mašín, Zdeněk; Smirnova, Olga

2017-08-02

We present the first ab initio multi-channel photoionization calculations for NO 2 in the vicinity of the 2 A 1 / 2 B 2 conical intersection, for a range of nuclear geometries, using our newly developed set of tools based on the ab initio multichannel R-matrix method. Electronic correlation is included in both the neutral and the scattering states of the molecule via configuration interaction. Configuration mixing is especially important around conical intersections and avoided crossings, both pertinent for NO 2 , and manifests itself via significant variations in photoelectron angular distributions. The method allows for a balanced and accurate description of the photoionization/photorecombination for a number of different ionic channels in a wide range of photoelectron energies up to 100 eV. Proper account of electron correlations is crucial for interpreting time-resolved signals in photoelectron spectroscopy and high harmonic generation (HHG) from polyatomic molecules.

On the Terminal Rotation Rates of Giant Planets

NASA Astrophysics Data System (ADS)

Batygin, Konstantin

2018-04-01

Within the general framework of the core-nucleated accretion theory of giant planet formation, the conglomeration of massive gaseous envelopes is facilitated by a transient period of rapid accumulation of nebular material. While the concurrent build-up of angular momentum is expected to leave newly formed planets spinning at near-breakup velocities, Jupiter and Saturn, as well as super-Jovian long-period extrasolar planets, are observed to rotate well below criticality. In this work, we demonstrate that the large luminosity of a young giant planet simultaneously leads to the generation of a strong planetary magnetic field, as well as thermal ionization of the circumplanetary disk. The ensuing magnetic coupling between the planetary interior and the quasi-Keplerian motion of the disk results in efficient braking of planetary rotation, with hydrodynamic circulation of gas within the Hill sphere playing the key role of expelling spin angular momentum to the circumstellar nebula. Our results place early-stage giant planet and stellar rotation within the same evolutionary framework, and motivate further exploration of magnetohydrodynamic phenomena in the context of the final stages of giant planet formation.

On Angular Momentum

DOE R&D Accomplishments Database

Schwinger, J.

1952-01-26

The commutation relations of an arbitrary angular momentum vector can be reduced to those of the harmonic oscillator. This provides a powerful method for constructing and developing the properties of angular momentum eigenvectors. In this paper many known theorems are derived in this way, and some new results obtained. Among the topics treated are the properties of the rotation matrices; the addition of two, three, and four angular momenta; and the theory of tensor operators.

Computer-aided trauma simulation system with haptic feedback is easy and fast for oral-maxillofacial surgeons to learn and use.

PubMed

Schvartzman, Sara C; Silva, Rebeka; Salisbury, Ken; Gaudilliere, Dyani; Girod, Sabine

2014-10-01

Computer-assisted surgical (CAS) planning tools have become widely available in craniomaxillofacial surgery, but are time consuming and often require professional technical assistance to simulate a case. An initial oral and maxillofacial (OM) surgical user experience was evaluated with a newly developed CAS system featuring a bimanual sense of touch (haptic). Three volunteer OM surgeons received a 5-minute verbal introduction to the use of a newly developed haptic-enabled planning system. The surgeons were instructed to simulate mandibular fracture reductions of 3 clinical cases, within a 15-minute time limit and without a time limit, and complete a questionnaire to assess their subjective experience with the system. Standard landmarks and linear and angular measurements between the simulated results and the actual surgical outcome were compared. After the 5-minute instruction, all 3 surgeons were able to use the system independently. The analysis of standardized anatomic measurements showed that the simulation results within a 15-minute time limit were not significantly different from those without a time limit. Mean differences between measurements of surgical and simulated fracture reductions were within current resolution limitations in collision detection, segmentation of computed tomographic scans, and haptic devices. All 3 surgeons reported that the system was easy to learn and use and that they would be comfortable integrating it into their daily clinical practice for trauma cases. A CAS system with a haptic interface that capitalizes on touch and force feedback experience similar to operative procedures is fast and easy for OM surgeons to learn and use. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. All rights reserved.

Angular and energy distribution of low energy cometary ions measured in the outer coma of Comet Halley

NASA Technical Reports Server (NTRS)

Berthelier, J. J.; Illiano, J. M.; Hodges, R. R.; Krankowsky, D.; Eberhardt, P.; Laemmerzahl, P.; Hoffman, J. H.; Herrwerth, I.; Woweries, J.; Dolder, U.

1986-01-01

During the early phase of the Giotto encounter with comet Halley, at distances from the nucleus greater than 350,000 km, the neutral mass spectrometer was operated in a mode allowing the measurement of low energy ions. Data reveal two important features of the outer coma: the presence of a sharp discontinuity in the plasma flow at 550,000 km from the nucleus which results in a significant decrease of the plasma flow accompanied by an increase in temperature; and the detection of newly born ions identified as O(+) and CO(+), at distances from the comet greater than 800,000 km.

Angular Positioning Sensor for Space Mechanisms

NASA Astrophysics Data System (ADS)

Steiner, Nicolas; Chapuis, Dominique

2013-09-01

Angular position sensors are used on various rotating mechanisms such as solar array drive mechanisms, antenna pointing mechanisms, scientific instruments, motors or actuators.Now a days, potentiometers and encoders are mainly used for angular measurement purposes. Both of them have their own pros and cons.As alternative, Ruag Space Switzerland Nyon (RSSN) is developing and qualifying two innovative technologies of angular position sensors which offer easy implementation, medium to very high lifetime and high flexibility with regards to the output signal shape/type.The Brushed angular position sensor uses space qualified processes which are already flying on RSSN's sliprings for many years. A large variety of output signal shape can be implemented to fulfill customer requirements (digital, analog, customized, etc.).The contactless angular position sensor consists in a new radiation hard Application Specific Integrated Circuit (ASIC) based on the Hall effect and providing the angular position without complex processing algorithm.

State-Dependent Pseudo-Linear Filter for Spacecraft Attitude and Rate Estimation

NASA Technical Reports Server (NTRS)

Bar-Itzhack, Itzhack Y.; Harman, Richard R.

2001-01-01

This paper presents the development and performance of a special algorithm for estimating the attitude and angular rate of a spacecraft. The algorithm is a pseudo-linear Kalman filter, which is an ordinary linear Kalman filter that operates on a linear model whose matrices are current state estimate dependent. The nonlinear rotational dynamics equation of the spacecraft is presented in the state space as a state-dependent linear system. Two types of measurements are considered. One type is a measurement of the quaternion of rotation, which is obtained from a newly introduced star tracker based apparatus. The other type of measurement is that of vectors, which permits the use of a variety of vector measuring sensors like sun sensors and magnetometers. While quaternion measurements are related linearly to the state vector, vector measurements constitute a nonlinear function of the state vector. Therefore, in this paper, a state-dependent linear measurement equation is developed for the vector measurement case. The state-dependent pseudo linear filter is applied to simulated spacecraft rotations and adequate estimates of the spacecraft attitude and rate are obtained for the case of quaternion measurements as well as of vector measurements.

Discovery potential for directional dark matter detection with nuclear emulsions

NASA Astrophysics Data System (ADS)

Guler, A. M.; NEWSdm Collaboration

2017-06-01

Direct Dark Matter searches are nowadays one of the most exciting research topics. Several Experimental efforts are concentrated on the development, construction, and operation of detectors looking for the scattering of target nuclei with Weakly Interactive Massive Particles (WIMPs). In this field a new frontier can be opened by directional detectors able to reconstruct the direction of the WIMP-recoiled nucleus thus allowing to extend dark matter searches beyond the neutrino floor. Exploiting directionality would also give a proof of the galactic origin of dark matter making it possible to have a clear and unambiguous signal to background separation. The angular distribution of WIPM-scattered nuclei is indeed expected to be peaked in the direction of the motion of the Solar System in the Galaxy, i.e. toward the Cygnus constellation, while the background distribution is expected to be isotropic. Current directional experiments are based on the use of gas TPC whose sensitivity is limited by the small achievable detector mass. In this paper we show the potentiality in terms of exclusion limit of a directional experiment based on the use of a solid target made by newly developed nuclear emulsions and read-out systems reaching sub-micrometric resolution.

Development of a High Accuracy Angular Measurement System for Langley Research Center Hypersonic Wind Tunnel Facilities

NASA Technical Reports Server (NTRS)

Newman, Brett; Yu, Si-bok; Rhew, Ray D. (Technical Monitor)

2003-01-01

Modern experimental and test activities demand innovative and adaptable procedures to maximize data content and quality while working within severely constrained budgetary and facility resource environments. This report describes development of a high accuracy angular measurement capability for NASA Langley Research Center hypersonic wind tunnel facilities to overcome these deficiencies. Specifically, utilization of micro-electro-mechanical sensors including accelerometers and gyros, coupled with software driven data acquisition hardware, integrated within a prototype measurement system, is considered. Development methodology addresses basic design requirements formulated from wind tunnel facility constraints and current operating procedures, as well as engineering and scientific test objectives. Description of the analytical framework governing relationships between time dependent multi-axis acceleration and angular rate sensor data and the desired three dimensional Eulerian angular state of the test model is given. Calibration procedures for identifying and estimating critical parameters in the sensor hardware is also addressed.

Optimal design of a smart post-buckled beam actuator using bat algorithm: simulations and experiments

NASA Astrophysics Data System (ADS)

Mallick, Rajnish; Ganguli, Ranjan; Kumar, Ravi

2017-05-01

The optimized design of a smart post-buckled beam actuator (PBA) is performed in this study. A smart material based piezoceramic stack actuator is used as a prime-mover to drive the buckled beam actuator. Piezoceramic actuators are high force, small displacement devices; they possess high energy density and have high bandwidth. In this study, bench top experiments are conducted to investigate the angular tip deflections due to the PBA. A new design of a linear-to-linear motion amplification device (LX-4) is developed to circumvent the small displacement handicap of piezoceramic stack actuators. LX-4 enhances the piezoceramic actuator mechanical leverage by a factor of four. The PBA model is based on dynamic elastic stability and is analyzed using the Mathieu-Hill equation. A formal optimization is carried out using a newly developed meta-heuristic nature inspired algorithm, named as the bat algorithm (BA). The BA utilizes the echolocation capability of bats. An optimized PBA in conjunction with LX-4 generates end rotations of the order of 15° at the output end. The optimized PBA design incurs less weight and induces large end rotations, which will be useful in development of various mechanical and aerospace devices, such as helicopter trailing edge flaps, micro and nano aerial vehicles and other robotic systems.

New Insights About Large-Scale Delta Morphodynamics from a Coupled Model of Fluvial-Coastal Processes

NASA Astrophysics Data System (ADS)

Murray, A. B.; Ratliff, K. M.; Hutton, E.

2017-12-01

We use a newly developed delta model to explore the combined effects of sea-level rise (SLR) and variable wave influence on delta morphology, avulsion behavior, and autogenic sediment flux variability. Using the Community Surface Dynamics Modeling System framework and tools, we couple the River Avulsion and Floodplain Evolution Model (RAFEM) to the Coastline Evolution Model (CEM). RAFEM models the fluvial processes, including river profile evolution, floodplain deposition, and avulsions. CEM uses gradients in alongshore sediment transport to distribute the fluvial sediment along the coastline. A suite of recent experiments using the coupled model and the Dakota software toolkit lead to several new insights: 1) A preferential avulsion location (which scales with the backwater length) can arise for geometric reasons that are independent of the recently suggested importance of alternation between flood and inter-flood periods. 2) The angular distribution of waves, as well as the wave height, affect the avulsion timescale. Previous work suggested that the time between avulsions will increase with greater wave influence, and we find that this is true for an angular mix of waves that tends to smooth a fairly straight coastline (coastline diffusion), where river mouth progradation is slowed and avulsions are delayed. However, if the angular distribution of waves leads to locally smooth shorelines but large amplitude coastline features (anti-diffusive coastline evolution), then avulsion timescales are barely affected, even when wave influence is high. 3) Increasing SLR rates are expected to cause more frequent avulsions, and it does in laboratory deltas. Unexpectedly, we find that this is not the case for the river-dominated deltas in our coupled model, in which SLR-related transgression effectively decreases progradation, offsetting base-level-rise effects. This finding raises potentially important questions about the geometric differences between prototypical and laboratory deltas that have not previously been addressed. 4) The magnitude and timescale of autogenic variability in the sediment flux at the river mouth depends on the SLR rate (for some wave climates), wave characteristics, and the how high the river channel must be super-elevated relative to the floodplain in order to trigger an avulsion.

Demonstrating the Conservation of Angular Momentum Using Model Cars Moving along a Rotating Rod

ERIC Educational Resources Information Center

Abdul-Razzaq, Wathiq; Golubovic, Leonardo

2013-01-01

We have developed an exciting non-traditional experiment for our introductory physics laboratories to help students to understand the principle of conservation of angular momentum. We used electric toy cars moving along a long rotating rod. As the cars move towards the centre of the rod, the angular velocity of this system increases.…

A fiber-coupled displacement measuring interferometer for determination of the posture of a reflective surface

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

Mao, Shuai; Hu, Peng-Cheng, E-mail: hupc@hit.edu.cn; Ding, Xue-Mei, E-mail: X.M.Ding@outlook.com

A fiber-coupled displacement measuring interferometer capable of determining of the posture of a reflective surface of a measuring mirror is proposed. The newly constructed instrument combines fiber-coupled displacement and angular measurement technologies. The proposed interferometer has advantages of both the fiber-coupled and the spatially beam-separated interferometer. A portable dual-position sensitive detector (PSD)-based unit within this proposed interferometer measures the parallelism of the two source beams to guide the fiber-coupling adjustment. The portable dual PSD-based unit measures not only the pitch and yaw of the retro-reflector but also measures the posture of the reflective surface. The experimental results of displacement calibrationmore » show that the deviations between the proposed interferometer and a reference one, Agilent 5530, at two different common beam directions are both less than ±35 nm, thus verifying the effectiveness of the beam parallelism measurement. The experimental results of angular calibration show that deviations of pitch and yaw with the auto-collimator (as a reference) are less than ±2 arc sec, thus proving the proposed interferometer’s effectiveness for determination of the posture of a reflective surface.« less

Effects of anisotropic electron-ion interactions in atomic photoelectron angular distributions

NASA Technical Reports Server (NTRS)

Dill, D.; Starace, A. F.; Manson, S. T.

1975-01-01

A summary of the angular momentum transfer formulation of the differential photoionization cross section is presented and photoionization amplitudes in LS coupling are considered. The application of the theoretical concepts and relations developed is illustrated with the aid of an example involving the calculation of the angular distribution of photoelectrons ionized from atomic sulfur according to a certain reaction. The investigation shows that anisotropic electron-ion interactions in atomic sulfur lead to measurable differences between photoelectron angular distribution asymmetry parameters corresponding to alternative ionic term levels.

Observation of circular dichroism in photoelectron angular distributions

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

Appling, J.R.; White, M.G.; Orlando, T.M.

1986-12-01

The first observations of dichroic effects in photoelectron angular distributions are reported for photoionization of aligned molecular excited states with circularly polarized light. Photoelectron angular distributions resulting from the two-color, (2+1) REMPI of NO via the A /sup 2/summation/sup +/, v = 0, J = 3/2,5/2 excited states exhibit significant left--right asymmetry. The experimental CD angular distributions are found to be well described by the general theoretical framework recently developed by Dubs, Dixit, and McKoy and are in good qualitative agreement with their calculated REMPI--CD distributions.

Observation of circular dichroism in photoelectron angular distributions

NASA Astrophysics Data System (ADS)

Appling, Jeffrey R.; White, Michael G.; Orlando, Thomas M.; Anderson, Scott L.

1986-12-01

The first observations of dichroic effects in photoelectron angular distributions are reported for photoionization of aligned molecular excited states with circularly polarized light. Photoelectron angular distributions resulting from the two-color, (2+1) REMPI of NO via the A 2∑+, v=0, J=3/2,5/2 excited states exhibit significant left-right asymmetry. The experimental CD angular distributions are found to be well described by the general theoretical framework recently developed by Dubs, Dixit, and McKoy and are in good qualitative agreement with their calculated REMPI-CD distributions.

Lifetimes in Te 124 : Examining critical-point symmetry in the Te nuclei

DOE PAGES

Hicks, S. F.; Vanhoy, J. R.; Burkett, P. G.; ...

2017-03-27

The Doppler-shift attenuation method following inelastic neutron scattering was used to determine the lifetimes of nuclear levels to 3.3-MeV excitation in 124Te. Level energies and spins, γ -ray energies and branching ratios, and multipole-mixing ratios were deduced from measured γ-ray angular distributions at incident neutron energies of 2.40 and 3.30 MeV, γ-ray excitation functions, and γγ coincidence measurements. The newly obtained reduced transition probabilities and level energies for 124Te were compared to critical-point symmetry model predictions. The E(5) and β 4 potential critical-point symmetries were also investigated in 122Te and 126Te.

Nuclear structure studies performed using the (18O,16O) two-neutron transfer reactions

NASA Astrophysics Data System (ADS)

Carbone, D.; Agodi, C.; Cappuzzello, F.; Cavallaro, M.; Ferreira, J. L.; Foti, A.; Gargano, A.; Lenzi, S. M.; Linares, R.; Lubian, J.; Santagati, G.

2018-02-01

Excitation energy spectra and absolute cross section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. This reaction selectively populates two-neutron configurations in the states of the residual nucleus. Exact finite-range coupled reaction channel calculations are used to analyse the data. Two approaches are discussed: the extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre of mass reference frame, derived from shell-model calculations using the Moshinsky transformation brackets. The results describe well the experimental cross section and highlight cluster configurations in the involved wave functions.

One Nucleon Transfer Reactions Around {sup 68}Ni at REX-ISOLDE

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

Patronis, N.; Raabe, R.; Bree, N.

2008-05-12

The newly built position sensitive Si detectors array of nearly 4{pi} angular coverage which is going to be installed at the REX-ISOLDE facility at CERN is briefly presented. This setup will be combined with the Miniball detectors array, constituting a unique tool for the study of one-nucleon transfer reactions. The experimental study of d({sup 66}Ni,p){sup 67}Ni reaction will be proposed, as a starting point for a series of experiments aiming to the study of the single particle character of the levels of the odd mass neutron reach unstable Ni isotopes. In this contribution, the feasibility and sensitivity of the experimentmore » is presented.« less

High-frequency Earth rotation variations deduced from altimetry-based ocean tides

NASA Astrophysics Data System (ADS)

Madzak, Matthias; Schindelegger, Michael; Böhm, Johannes; Bosch, Wolfgang; Hagedoorn, Jan

2016-11-01

A model of diurnal and semi-diurnal variations in Earth rotation parameters (ERP) is constructed based on altimetry-measured tidal heights from a multi-mission empirical ocean tide solution. Barotropic currents contributing to relative angular momentum changes are estimated for nine major tides in a global inversion algorithm that solves the two-dimensional momentum equations on a regular 0.5° grid with a heavily weighted continuity constraint. The influence of 19 minor tides is accounted for by linear admittance interpolation of ocean tidal angular momentum, although the assumption of smooth admittance variations with frequency appears to be a doubtful concept for semi-diurnal mass terms in particular. A validation of the newly derived model based on post-fit corrections to polar motion and universal time (Δ UT1) from the analysis of Very Long Baseline Interferometry (VLBI) observations shows a variance reduction for semi-diurnal Δ UT1 residuals that is significant at the 0.05 level with respect to the conventional ERP model. Improvements are also evident for the explicitly modeled K_1, Q_1, and K_2 tides in individual ERP components, but large residuals of more than 15 μ as remain at the principal lunar frequencies of O_1 and M_2. We attribute these shortcomings to uncertainties in the inverted relative angular momentum changes and, to a minor extent, to violation of mass conservation in the empirical ocean tide solution. Further dedicated hydrodynamic modeling efforts of these anomalous constituents are required to meet the accuracy standards of modern space geodesy.

A Diels-Alder Route to Angularly Functionalized Bicyclic Structures

PubMed Central

Kim, Woo Han; Lee, Jun Hee; Aussedat, Baptiste; Danishefsky, Samuel J.

2010-01-01

A Diels-Alder based route to trans-fused angularly functionalized bicyclic structures has been developed. This transformation features the use of a tetrasubstituted dienophile in the cycloaddition step. PMID:20717474

Orthodontics: computer-aided diagnosis and treatment planning

NASA Astrophysics Data System (ADS)

Yi, Yaxing; Li, Zhongke; Wei, Suyuan; Deng, Fanglin; Yao, Sen

2000-10-01

The purpose of this article is to introduce the outline of our newly developed computer-aided 3D dental cast analyzing system with laser scanning, and its preliminary clinical applications. The system is composed of a scanning device and a personal computer as a scanning controller and post processor. The scanning device is composed of a laser beam emitter, two sets of linear CCD cameras and a table which is rotatable by two-degree-of-freedom. The rotating is controlled precisely by a personal computer. The dental cast is projected and scanned with a laser beam. Triangulation is applied to determine the location of each point. Generation of 3D graphics of the dental cast takes approximately 40 minutes. About 170,000 sets of X,Y,Z coordinates are store for one dental cast. Besides the conventional linear and angular measurements of the dental cast, we are also able to demonstrate the size of the top surface area of each molar. The advantage of this system is that it facilitates the otherwise complicated and time- consuming mock surgery necessary for treatment planning in orthognathic surgery.

A positional misalignment correction method for Fourier ptychographic microscopy based on simulated annealing

NASA Astrophysics Data System (ADS)

Sun, Jiasong; Zhang, Yuzhen; Chen, Qian; Zuo, Chao

2017-02-01

Fourier ptychographic microscopy (FPM) is a newly developed super-resolution technique, which employs angularly varying illuminations and a phase retrieval algorithm to surpass the diffraction limit of a low numerical aperture (NA) objective lens. In current FPM imaging platforms, accurate knowledge of LED matrix's position is critical to achieve good recovery quality. Furthermore, considering such a wide field-of-view (FOV) in FPM, different regions in the FOV have different sensitivity of LED positional misalignment. In this work, we introduce an iterative method to correct position errors based on the simulated annealing (SA) algorithm. To improve the efficiency of this correcting process, large number of iterations for several images with low illumination NAs are firstly implemented to estimate the initial values of the global positional misalignment model through non-linear regression. Simulation and experimental results are presented to evaluate the performance of the proposed method and it is demonstrated that this method can both improve the quality of the recovered object image and relax the LED elements' position accuracy requirement while aligning the FPM imaging platforms.

State-to-state reactive scattering in six dimensions using reactant-product decoupling: OH + H2 → H2O + H (J = 0).

PubMed

Cvitaš, Marko T; Althorpe, Stuart C

2011-01-14

We extend to full dimensionality a recently developed wave packet method [M. T. Cvitaš and S. C. Althorpe, J. Phys. Chem. A 113, 4557 (2009)] for computing the state-to-state quantum dynamics of AB + CD → ABC + D reactions and also increase the computational efficiency of the method. This is done by introducing a new set of product coordinates, by applying the Crank-Nicholson approximation to the angular kinetic energy part of the split-operator propagator and by using a symmetry-adapted basis-to-grid transformation to evaluate integrals over the potential energy surface. The newly extended method is tested on the benchmark OH + H(2) → H(2)O + H reaction, where it allows us to obtain accurately converged state-to-state reaction probabilities (on the Wu-Schatz-Fang-Lendvay-Harding potential energy surface) with modest computational effort. These methodological advances will make possible efficient calculations of state-to-state differential cross sections on this system in the near future.

Book Review:

NASA Astrophysics Data System (ADS)

Arimondo, Ennio

2004-07-01

For many years the Institute of Physics has published books on hot topics based on a collection of reprints from different journals, including some remarks by the editors of each volume. The book on Optical Angular Momentum, edited by L Allen, S M Barnett and M J Padgett, is a recent addition to the series. It reproduces forty four papers originally published in different journals and in a few cases it provides direct access to works not easily accessible to a web navigator. The collection covers nearly a hundred years of progress in physics, starting from an historic 1909 paper by Poynting, and ending with a 2002 paper by Padgett, Barnett and coworkers on the measurement of the orbital angular momentum of a single photon. The field of optical angular momentum has expanded greatly, creating an interdisciplinary attraction for researchers operating in quantum optics, atomic physics, solid state physics, biophysics and quantum information theory. The development of laser optics, especially the control of single mode sources, has made possible the specific design of optical radiation modes with a high degree of control on the light angular momentum. The editors of this book are important figures in the field of angular momentum, having contributed to key progress in the area. L Allen published an historical paper in 1999, he and M J Padgett (together with M Babiker) produced few years ago a long review article which is today still the most complete basic introduction to the angular momentum of light, while S M Barnett has contributed several high quality papers to the progress of this area of physics. The editors' choice provides an excellent overview to all readers, with papers classified into eight different topics, covering the basic principles of the light and spin and orbital angular momentum, the laboratory tools for creating laser beams carrying orbital angular momentum, the optical forces and torques created by laser beams carrying angular momentum on particles and atoms, the rotational frequency shift, the angular momentum in nonlinear optics, and the entanglement of angular momentum. An introductory part contains the historic paper by Poynting mentioned above, and another one by Beth in 1936 where the angular momentum of light was measured through a mechanical detection. It also includes a paper by Allen written in 2002 as a long foreword to a Special Issue of Journal of Optics B: Quantum and Semiclassical Optics where more recent major developments within this field were illustrated. Both experimental and theoretical aspects of orbital angular momentum are covered, the editors themselves having, in fact, contributed to developments in both aspects. A newcomer to the field will immediately realize the most important issues connected to the generation, propagation and application of laser beams with orbital angular momentum. A reader already acquainted with the main features of the topic may skip the first papers of all the sections listed above, and focus his or her attention to those papers devoted to the more recent developments. This is therefore a book to be considered with great attention by a large community. My only, minor, remark on the choice of the papers reproduced within this book is that applications to solid state physics, such as liquid crystals, are not mentioned. The field keeps expanding. For instance, very recently optical beams bearing optical angular momentum have been recognized as potential systems for doing quantum computation. Optical tweezers have defined a revolution in optical manipulation for research in the fields of biology, physical chemistry and soft condensed matter physics. The angular momentum of light also has applications in atom optics. Good textbooks are essential in establishing and expanding any field; they help broaden the interest in the field and ensure that the next generation of physicists can learn it. The present book satisfies those requirements because it provides to graduate students, to newcomers to the field, and also to experienced researchers an easy access to the basic contributions.

Development and Validation of a Method for Determining Tridimensional Angular Displacements with Special Applications to Ice Hockey Motions.

ERIC Educational Resources Information Center

Gagnon, Micheline; And Others

1983-01-01

A method for determining the tridimensional angular displacement of skates during the two-legged stop in ice hockey was developed and validated. The angles were measured by geometry, using a cinecamera and specially equipped skates. The method provides a new tool for kinetic analyses of skating movements. (Authors/PP)

The mass and angular momentum of reconstructed metric perturbations

NASA Astrophysics Data System (ADS)

van de Meent, Maarten

2017-06-01

We prove a key result regarding the mass and angular momentum content of linear vacuum perturbations of the Kerr metric obtained through the formalism developed by Chrzarnowski, Cohen, and Kegeles (CCK). More precisely, we prove that the Abbott-Deser mass and angular momentum integrals of any such perturbation vanish when that perturbation was obtained from a regular Fourier mode of the Hertz potential. As a corollary we obtain a generalization of previous results on the completion of the ‘no string’ radiation gauge metric perturbation generated by a point particle. We find that for any bound orbit around a Kerr black hole, the mass and angular momentum perturbations completing the CCK metric are simply the energy and angular momentum of the particle ‘outside’ the orbit and vanish ‘inside’ the orbit.

Angular Rate Sensing with GyroWheel Using Genetic Algorithm Optimized Neural Networks.

PubMed

Zhao, Yuyu; Zhao, Hui; Huo, Xin; Yao, Yu

2017-07-22

GyroWheel is an integrated device that can provide three-axis control torques and two-axis angular rate sensing for small spacecrafts. Large tilt angle of its rotor and de-tuned spin rate lead to a complex and non-linear dynamics as well as difficulties in measuring angular rates. In this paper, the problem of angular rate sensing with the GyroWheel is investigated. Firstly, a simplified rate sensing equation is introduced, and the error characteristics of the method are analyzed. According to the analysis results, a rate sensing principle based on torque balance theory is developed, and a practical way to estimate the angular rates within the whole operating range of GyroWheel is provided by using explicit genetic algorithm optimized neural networks. The angular rates can be determined by the measurable values of the GyroWheel (including tilt angles, spin rate and torque coil currents), the weights and the biases of the neural networks. Finally, the simulation results are presented to illustrate the effectiveness of the proposed angular rate sensing method with GyroWheel.

Developments in Human Centered Cueing Algorithms for Control of Flight Simulator Motion Systems

NASA Technical Reports Server (NTRS)

Houck, Jacob A.; Telban, Robert J.; Cardullo, Frank M.

1997-01-01

The authors conducted further research with cueing algorithms for control of flight simulator motion systems. A variation of the so-called optimal algorithm was formulated using simulated aircraft angular velocity input as a basis. Models of the human vestibular sensation system, i.e. the semicircular canals and otoliths, are incorporated within the algorithm. Comparisons of angular velocity cueing responses showed a significant improvement over a formulation using angular acceleration input. Results also compared favorably with the coordinated adaptive washout algorithm, yielding similar results for angular velocity cues while eliminating false cues and reducing the tilt rate for longitudinal cues. These results were confirmed in piloted tests on the current motion system at NASA-Langley, the Visual Motion Simulator (VMS). Proposed future developments by the authors in cueing algorithms are revealed. The new motion system, the Cockpit Motion Facility (CMF), where the final evaluation of the cueing algorithms will be conducted, is also described.

Microstructure development during equal channel angular drawing of Al at room temperature

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

Chakkingal, U.; Suriadi, A.B.; Thomson, P.F.

1998-08-11

In this study 3004 aluminum alloy can-stock remelt (composition 99.9% Al) was subjected to Equal Channel Angular Drawing (ECAD) at room temperature. Tests were conducted to an applied true strain of 2.95. Mechanical properties like tensile strength, ductility at fracture, and microhardness were measured. The development of the substructure was studied using optical and transmission electron microscopy. Subgrain sizes and their angular misorientations were measured as a function of the applied strain. In general, a substructure that consists of cells and subgrains was seen to evolve, as is expected for the case of high SFE fcc metals.

Dynamic approach to description of entrance channel effects in angular distributions of fission fragments

NASA Astrophysics Data System (ADS)

Eremenko, D. O.; Drozdov, V. A.; Fotina, O. V.; Platonov, S. Yu.; Yuminov, O. A.

2016-07-01

Background: It is well known that the anomalous behavior of angular anisotropies of fission fragments at sub- and near-barrier energies is associated with a memory of conditions in the entrance channel of the heavy-ion reactions, particularly, deformations and spins of colliding nuclei that determine the initial distributions for the components of the total angular momentum over the symmetry axis of the fissioning system and the beam axis. Purpose: We develop a new dynamic approach, which allows the description of the memory effects in the fission fragment angular distributions and provides new information on fusion and fission dynamics. Methods: The approach is based on the dynamic model of the fission fragment angular distributions which takes into account stochastic aspects of nuclear fission and thermal fluctuations for the tilting mode that is characterized by the projection of the total angular momentum onto the symmetry axis of the fissioning system. Another base of our approach is the quantum mechanical method to calculate the initial distributions over the components of the total angular momentum of the nuclear system immediately following complete fusion. Results: A method is suggested for calculating the initial distributions of the total angular momentum projection onto the symmetry axis for the nuclear systems formed in the reactions of complete fusion of deformed nuclei with spins. The angular distributions of fission fragments for the 16O+232Th,12C+235,236,238, and 13C+235U reactions have been analyzed within the dynamic approach over a range of sub- and above-barrier energies. The analysis allowed us to determine the relaxation time for the tilting mode and the fraction of fission events occurring in times not larger than the relaxation time for the tilting mode. Conclusions: It is shown that the memory effects play an important role in the formation of the angular distributions of fission fragments for the reactions induced by heavy ions. The approach developed for analysis of the effects is a suitable tool to get insight into the complete fusion-fission dynamics, in particular, to investigate the mechanism of the complete fusion and fission time scale.

Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators.

PubMed

Eichmann, Marion; Flühs, Dirk; Spaan, Bernhard

2009-10-01

The therapeutic outcome of the therapy with ophthalmic applicators is highly dependent on the application of a sufficient dose to the tumor, whereas the dose applied to the surrounding tissue needs to be minimized. The goal for the newly developed apparatus described in this work is the determination of the individual applicator surface dose rate distribution with a high spatial resolution and a high precision in dose rate with respect to time and budget constraints especially important for clinical procedures. Inhomogeneities of the dose rate distribution can be detected and taken into consideration for the treatment planning. In order to achieve this, a dose rate profile as well as a surface profile of the applicator are measured and correlated with each other. An instrumental setup has been developed consisting of a plastic scintillator detector system and a newly designed apparatus for guiding the detector across the applicator surface at a constant small distance. It performs an angular movement of detector and applicator with high precision. The measurements of surface dose rate distributions discussed in this work demonstrate the successful operation of the measuring setup. Measuring the surface dose rate distribution with a small distance between applicator and detector and with a high density of measuring points results in a complete and gapless coverage of the applicator surface, being capable of distinguishing small sized spots with high activities. The dosimetrical accuracy of the measurements and its analysis is sufficient (uncertainty in the dose rate in terms of absorbed dose to water is <7%), especially when taking the surgical techniques in positioning of the applicator on the eyeball into account. The method developed so far allows a fully automated quality assurance of eye applicators even under clinical conditions. These measurements provide the basis for future calculation of a full 3D dose rate distribution, which then can be used as input for a refined clinical treatment planning system. The improved dose rate measurements will facilitate a clinical study, which could correlate the therapeutic outcome of a brachytherapy treatment with an applicator and its individual dose rate distribution.

Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators

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

Eichmann, Marion; Fluehs, Dirk; Spaan, Bernhard

2009-10-15

Purpose: The therapeutic outcome of the therapy with ophthalmic applicators is highly dependent on the application of a sufficient dose to the tumor, whereas the dose applied to the surrounding tissue needs to be minimized. The goal for the newly developed apparatus described in this work is the determination of the individual applicator surface dose rate distribution with a high spatial resolution and a high precision in dose rate with respect to time and budget constraints especially important for clinical procedures. Inhomogeneities of the dose rate distribution can be detected and taken into consideration for the treatment planning. Methods: Inmore » order to achieve this, a dose rate profile as well as a surface profile of the applicator are measured and correlated with each other. An instrumental setup has been developed consisting of a plastic scintillator detector system and a newly designed apparatus for guiding the detector across the applicator surface at a constant small distance. It performs an angular movement of detector and applicator with high precision. Results: The measurements of surface dose rate distributions discussed in this work demonstrate the successful operation of the measuring setup. Measuring the surface dose rate distribution with a small distance between applicator and detector and with a high density of measuring points results in a complete and gapless coverage of the applicator surface, being capable of distinguishing small sized spots with high activities. The dosimetrical accuracy of the measurements and its analysis is sufficient (uncertainty in the dose rate in terms of absorbed dose to water is <7%), especially when taking the surgical techniques in positioning of the applicator on the eyeball into account. Conclusions: The method developed so far allows a fully automated quality assurance of eye applicators even under clinical conditions. These measurements provide the basis for future calculation of a full 3D dose rate distribution, which then can be used as input for a refined clinical treatment planning system. The improved dose rate measurements will facilitate a clinical study, which could correlate the therapeutic outcome of a brachytherapy treatment with an applicator and its individual dose rate distribution.« less

Incorporation of nanovoids into metallic gratings for broadband plasmonic organic solar cells.

PubMed

Lee, Sangjun; In, Sungjun; Mason, Daniel R; Park, Namkyoo

2013-02-25

We present investigation and optimization of a newly proposed plasmonic organic solar cell geometry based on the incorporation of nanovoids into conventional rectangular backplane gratings. Hybridization of strongly localized plasmonic modes of the nanovoids with Fabry-Perot cavity modes originating from surface plasmon reflection at the grating elements is shown to significantly boost performance in the long wavelength regime. This constitutes improved broadband operation while maintaining absorption enhancements at short wavelengths derived from conventional rectangular grating. Our calculations predict a figure of merit enhancement of up to 41% compared to when the nanovoid indented grating is absent. This is a significant improvement over the previously considered rectangular grating structures, which is further shown to be maintained over the entire angular range.

Nonlinear Mixing of Optical Vortices with Fractional Topological Charges in Raman Sideband Generation.

NASA Astrophysics Data System (ADS)

Strohaber, James; Boran, Yakup; Sayrac, Muhammed; Johnson, Lewis; Zhu, Feng; Kolomenskii, Alexandre; Schuessler, Hans

We studied the nonlinear parametric interaction of femtosecond fractionally-charged optical vortices in a Raman-active medium. Propagation of such beams is described using the Kirchhoff-Fresnel integrals by embedding a non-integer 2pi phase step in a Gaussian beam profile. When using fractionally-charged pump or Stokes beams, we observed the production of new topological charge and phase discontinuities in the Raman field. These newly generated fractionally-charged Raman vortex beams were found to follow the same orbital angular momentum algebra derived by for integer vortex beams. This work was funded by the Robert A. Welch Foundation, Grant No. A1546 and the Qatar Foundation under Grants No. NPRP 6-465-1-091.

Proton-proton elastic scattering excitation functions at intermediate energies

NASA Astrophysics Data System (ADS)

Rohdjess, H.

1998-05-01

Polarized and unpolarized proton-proton elastic scattering is investigated with the EDDA-experiment at the Cooler Synchrotron COSY at Jülich to significantly improve the world data base in the beam energy range 500-2500 MeV. Measurements during beam acceleration with thin internal targets and a large acceptance detector provide excitation functions over a broad angular and energy range with unprecedented internal consistency. Data taking with an unpolarized CH2 fiber target and an unpolarized beam have been completed and the derived differential cross sections are presented and compared to a recent phase shift analysis. With a polarized atomic beam target newly installed in COSY and a polarized COSY beam—currently under development—the measurements will be extended to analyzing powers and spin correlation parameters.

Adaptive Square-Root Cubature-Quadrature Kalman Particle Filter for satellite attitude determination using vector observations

NASA Astrophysics Data System (ADS)

Kiani, Maryam; Pourtakdoust, Seid H.

2014-12-01

A novel algorithm is presented in this study for estimation of spacecraft's attitudes and angular rates from vector observations. In this regard, a new cubature-quadrature particle filter (CQPF) is initially developed that uses the Square-Root Cubature-Quadrature Kalman Filter (SR-CQKF) to generate the importance proposal distribution. The developed CQPF scheme avoids the basic limitation of particle filter (PF) with regards to counting the new measurements. Subsequently, CQPF is enhanced to adjust the sample size at every time step utilizing the idea of confidence intervals, thus improving the efficiency and accuracy of the newly proposed adaptive CQPF (ACQPF). In addition, application of the q-method for filter initialization has intensified the computation burden as well. The current study also applies ACQPF to the problem of attitude estimation of a low Earth orbit (LEO) satellite. For this purpose, the undertaken satellite is equipped with a three-axis magnetometer (TAM) as well as a sun sensor pack that provide noisy geomagnetic field data and Sun direction measurements, respectively. The results and performance of the proposed filter are investigated and compared with those of the extended Kalman filter (EKF) and the standard particle filter (PF) utilizing a Monte Carlo simulation. The comparison demonstrates the viability and the accuracy of the proposed nonlinear estimator.

Scattering Matrix for Typical Urban Anthropogenic Origin Cement Dust and Discrimination of Representative Atmospheric Particulates

NASA Astrophysics Data System (ADS)

Liu, Jia; Zhang, Yongming; Zhang, Qixing; Wang, Jinjun

2018-03-01

The complete scattering matrix for cement dust was measured as a function of scattering angle from 5° to 160° at a wavelength of 532 nm, as a representative of mineral dust of anthropogenic origin in urban areas. Other related characteristics of cement dust, such as particle size distribution, chemical composition, refractive index, and micromorphology, were also analyzed. For this objective, a newly improved apparatus was built and calibrated using water droplets. Measurements of water droplets were in good agreement with Lorenz-Mie calculations. To facilitate the direct applicability of measurements for cement dust in radiative transfer calculation, the synthetic scattering matrix was computed and defined over the full scattering angle range from 0° to 180°. The scattering matrices for cement dust and typical natural mineral dusts were found to be similar in trends and angular behaviors. Angular distributions of all matrix elements were confined to rather limited domains. To promote the application of light-scattering matrix in atmospheric observation and remote sensing, discrimination methods for various atmospheric particulates (cement dust, soot, smolder smoke, and water droplets) based on the angular distributions of their scattering matrix elements are discussed. The ratio -F12/F11 proved to be the most effective discrimination method when a single matrix element is employed; aerosol identification can be achieved based on -F12/F11 values at 90° and 160°. Meanwhile, the combinations of -F12/F11 with F22/F11 (or (F11 - F22)/(F11 + F22)) or -F12/F11 with F44/F11 at 160° can be used when multiple matrix elements at the same scattering angle are selected.

Three-dimensional Frankfort horizontal plane for 3D cephalometry: a comparative assessment of conventional versus novel landmarks and horizontal planes.

PubMed

Pittayapat, Pisha; Jacobs, Reinhilde; Bornstein, Michael M; Odri, Guillaume A; Lambrichts, Ivo; Willems, Guy; Politis, Constantinus; Olszewski, Raphael

2018-05-25

To assess the reproducibility of landmarks in three dimensions that determine the Frankfort horizontal plane (FH) as well as two new landmarks, and to evaluate the angular differences of newly introduced planes to the FH. Three-dimensional (3D) surface models were created from CBCT scans of 26 dry human skulls. Porion (Po), orbitale (Or), internal acoustic foramen (IAF), and zygomatico-maxillary suture (ZyMS) were indicated in the software by three observers twice with a 4-week interval. Angles between two FHs (FH 1: Or-R, Or-L, mid-Po; FH 2: Po-R, Po-L, mid-Or) and between FHs and new planes (Plane 1-6) were measured. Coordinates were exported to a spreadsheet. A statistical analysis was performed to define the landmark reproducibility and 3D angles. Intra- and inter-observer landmark reproducibility showed mean difference more than 1 mm for x-coordinates of all landmarks except IAF. IAF showed significantly better reproducibility than other landmarks (P < 0.0018). The mean angular difference between FH 1 and FH 2 was 0.7 degrees. Plane 3, connecting Or-R, Or-L and mid-IAF, and Plane 4, connecting Po-R, Po-L and mid-ZyMS, both showed an angular difference of less than 1 degree when compared to FHs. This study revealed poor reproducibility of the traditional FH landmarks on the x-axis and good reproducibility of a new landmark tested to replace Po, the IAF. Yet, Or showed superior results compared to ZyMS. The potential of using new horizontal planes was demonstrated. Future studies should focus on identification of a valid alternative for Or and ZyMS and on clinical implementation of the findings.

Quantifying the impact of mergers on the angular momentum of simulated galaxies

NASA Astrophysics Data System (ADS)

Lagos, Claudia del P.; Stevens, Adam R. H.; Bower, Richard G.; Davis, Timothy A.; Contreras, Sergio; Padilla, Nelson D.; Obreschkow, Danail; Croton, Darren; Trayford, James W.; Welker, Charlotte; Theuns, Tom

2018-02-01

We use EAGLE to quantify the effect galaxy mergers have on the stellar specific angular momentum of galaxies, jstars. We split mergers into dry (gas-poor)/wet (gas-rich), major/minor and different spin alignments and orbital parameters. Wet (dry) mergers have an average neutral gas-to-stellar mass ratio of 1.1 (0.02), while major (minor) mergers are those with stellar mass ratios ≥0.3 (0.1-0.3). We correlate the positions of galaxies in the jstars-stellar mass plane at z = 0 with their merger history, and find that galaxies of low spins suffered dry mergers, while galaxies of normal/high spins suffered predominantly wet mergers, if any. The radial jstars profiles of galaxies that went through dry mergers are deficient by ≈0.3 dex at r ≲ 10 r50 (with r50 being the half-stellar mass radius), compared to galaxies that went through wet mergers. Studying the merger remnants reveals that dry mergers reduce jstars by ≈30 per cent, while wet mergers increase it by ≈10 per cent, on average. The latter is connected to the build-up of the bulge by newly formed stars of high rotational speed. Moving from minor to major mergers accentuates these effects. When the spin vectors of the galaxies prior to the dry merger are misaligned, jstars decreases by a greater magnitude, while in wet mergers corotation and high orbital angular momentum efficiently spun-up galaxies. We predict what would be the observational signatures in the jstars profiles driven by dry mergers: (i) shallow radial profiles and (ii) profiles that rise beyond ≈10 r50, both of which are significantly different from spiral galaxies.

Type II Migration and Giant Planet Survival

NASA Technical Reports Server (NTRS)

Ward, William R.

2003-01-01

Type II migration, in which a newly formed large planet opens a gap in its precursor circumstellar nebula and subsequently evolves with it, has been implicated as a delivery mechanism responsible for close stellar companions. Large scale migration is possible in a viscously spreading disk of surface density sigma (r,t) when most of it is sacrificed to the primary in order to promote a small portion of the disk to much higher angular momentum orbits. Embedded planets generally follow its evolution unless their own angular momentum is comparable to that of the disk. The fraction of the starting disk mass, M (sub d) = 2pi integral rsigma(r,0)dr, that is consumed by the star depends on the distance at which material escapes the disk's outer boundary. If the disk is allowed to expand indefinitely, virtually all of the disk will fall into the primary in order to send a vanishingly small portion to infinity. For such a case, it is difficult to explain the survival of any giant planets, including Jupiter and Saturn. Realistically, however, there are processes that could truncate a disk at a finite distance, r(sub d). Recent numerical modeling has illustrated that planets can survive in this case. We show here that much of these results can be understood by simple conservation arguments.

Correcting the lobule in otoplasty using the fillet technique.

PubMed

Sadick, Haneen; Artinger, Verena M; Haubner, Frank; Gassner, Holger G

2014-01-01

Correction of the protruded lobule in otoplasty continues to represent an important challenge. The lack of skeletal elements within the lobule makes a controlled lobule repositioning less predictable. OBJECTIVE To present a new surgical technique for lobule correction in otoplasty. Human cadaver studies were performed for detailed anatomical analysis of lobule deformities. In addition, we evaluated a novel algorithmic approach to correction of the lobule in 12 consecutive patients. INTERVENTIONS/EXPOSURES: Otoplasty with surgical correction of lobule using the fillet technique. The surgical outcome in the 12 most recent consecutive patients with at least 3 months of follow-up was assessed retrospectively. The postsurgical results were independently reviewed by a panel of noninvolved experts. The 3 major anatomic components of lobular deformities are the axial angular protrusion, the coronal angular protrusion, and the inherent shape. The fillet technique described in the present report addressed all 3 aspects in an effective way. Clinical data analysis revealed no immediate or long-term complications associated with this new surgical method. The patients' subjective rating and the panel's objective rating revealed "good" to "very good" postoperative results. This newly described fillet technique represents a safe and efficient method to correct protruded ear lobules in otoplasty. It allows precise and predictable positioning of the lobule with an excellent safety profile. 4.

Identification of trunk and pelvis movement compensations in patients with transtibial amputation using angular momentum separation.

PubMed

Gaffney, Brecca M; Murray, Amanda M; Christiansen, Cory L; Davidson, Bradley S

2016-03-01

Patients with unilateral dysvascular transtibial amputation (TTA) have a higher risk of developing low back pain than their healthy counterparts, which may be related to movement compensations used in the absence of ankle function. Assessing components of segmental angular momentum provides a unique framework to identify and interpret these movement compensations alongside traditional observational analyses. Angular momentum separation indicates two components of total angular momentum: (1) transfer momentum and (2) rotational momentum. The objective of this investigation was to assess movement compensations in patients with dysvascular TTA, patients with diabetes mellitus (DM), and healthy controls (HC) by examining patterns of generating and arresting trunk and pelvis segmental angular momenta during gait. We hypothesized that all groups would demonstrate similar patterns of generating/arresting total momentum and transfer momentum in the trunk and pelvis in reference to the groups (patients with DM and HC). We also hypothesized that patients with amputation would demonstrate different (larger) patterns of generating/arresting rotational angular momentum in the trunk. Patients with amputation demonstrated differences in trunk and pelvis transfer angular momentum in the sagittal and transverse planes in comparison to the reference groups, which indicates postural compensations adopted during walking. However, patients with amputation demonstrated larger patterns of generating and arresting of trunk and pelvis rotational angular momentum in comparison to the reference groups. These segmental rotational angular momentum patterns correspond with high eccentric muscle demands needed to arrest the angular momentum, and may lead to consequential long-term effects such as low back pain. Copyright © 2016 Elsevier B.V. All rights reserved.

A time-dependent neutron transport method of characteristics formulation with time derivative propagation

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

Hoffman, Adam J., E-mail: adamhoff@umich.edu; Lee, John C., E-mail: jcl@umich.edu

2016-02-15

A new time-dependent Method of Characteristics (MOC) formulation for nuclear reactor kinetics was developed utilizing angular flux time-derivative propagation. This method avoids the requirement of storing the angular flux at previous points in time to represent a discretized time derivative; instead, an equation for the angular flux time derivative along 1D spatial characteristics is derived and solved concurrently with the 1D transport characteristic equation. This approach allows the angular flux time derivative to be recast principally in terms of the neutron source time derivatives, which are approximated to high-order accuracy using the backward differentiation formula (BDF). This approach, called Sourcemore » Derivative Propagation (SDP), drastically reduces the memory requirements of time-dependent MOC relative to methods that require storing the angular flux. An SDP method was developed for 2D and 3D applications and implemented in the computer code DeCART in 2D. DeCART was used to model two reactor transient benchmarks: a modified TWIGL problem and a C5G7 transient. The SDP method accurately and efficiently replicated the solution of the conventional time-dependent MOC method using two orders of magnitude less memory.« less

Orbital Angular Momentum Multiplexing over Visible Light Communication Systems

NASA Astrophysics Data System (ADS)

Tripathi, Hardik Rameshchandra

This thesis proposes and explores the possibility of using Orbital Angular Momentum multiplexing in Visible Light Communication system. Orbital Angular Momentum is mainly applied for laser and optical fiber transmissions, while Visible Light Communication is a technology using the light as a carrier for wireless communication. In this research, the study of the state of art and experiments showing some results on multiplexing based on Orbital Angular Momentum over Visible Light Communication system were done. After completion of the initial stage; research work and simulations were performed on spatial multiplexing over Li-Fi channel modeling. Simulation scenarios which allowed to evaluate the Signal-to-Noise Ratio, Received Power Distribution, Intensity and Illuminance were defined and developed.

Investigation of fluctuations in angular velocity in magnetic memory devices

NASA Technical Reports Server (NTRS)

Meshkis, Y. A.; Potsyus, Z. Y.

1973-01-01

The fluctuations in the angular velocity of individual assemblies of a precision mechanical system were analyzed. The system was composed of an electric motor and a magnetic drum which were connected by a flexible coupling. A dynamic model was constructed which took into account the absence of torsion in the rigid shafts of the electric motor drive rotor and the magnetic drum. The motion was described by Lagrange differential equations of the second kind. Curves are developed to show the nature of amplitude fluctuation of the magnetic drum angular velocity at a specific excitation frequency. Additional curves show the amplitudes of fluctuation of the magnetic drum angular velocity compared to the quantity of damping at specific frequencies.

An investigation of angular stiffness and damping coefficients of an axial spline coupling in high-speed rotating machinery

NASA Technical Reports Server (NTRS)

Ku, C.-P. Roger; Walton, James F., Jr.; Lund, Jorgen W.

1994-01-01

This paper provided an opportunity to quantify the angular stiffness and equivalent viscous damping coefficients of an axial spline coupling used in high-speed turbomachinery. A unique test methodology and data reduction procedures were developed. The bending moments and angular deflections transmitted across an axial spline coupling were measured while a nonrotating shaft was excited by an external shaker. A rotor dynamics computer program was used to simulate the test conditions and to correlate the angular stiffness and damping coefficients. In addition, sensitivity analyses were performed to show that the accuracy of the dynamic coefficients do not rely on the accuracy of the data reduction procedures.

Measurement of irregularities in angular velocities of rotating assemblies in memory devices on magnetic carriers

NASA Technical Reports Server (NTRS)

Virakas, G. I.; Matsyulevichyus, R. A.; Minkevichyus, K. P.; Potsyus, Z. Y.; Shirvinskas, B. D.

1973-01-01

Problems in measurement of irregularities in angular velocity of rotating assemblies in memory devices with rigid and flexible magnetic data carriers are discussed. A device and method for determination of change in angular velocities in various frequency and rotation rate ranges are examined. A schematic diagram of a photoelectric sensor for recording the signal pulses is provided. Mathematical models are developed to show the amount of error which can result from misalignment of the test equipment.

The INCAS Project: An Innovative Contact-Less Angular Sensor

NASA Astrophysics Data System (ADS)

Ghislanzoni, L.; Di Cintio, A.; Solimando, M.; Parzianello, G.

2013-09-01

Angular Positions sensors are widely used in all spacecrafts, including re-entry vehicles and launchers, where mechanisms and pointing-scanning devices are required. The main applications are on mechanisms for TeleMeasure (TM) related to the release and deployment of devices, or on rotary mechanisms such as Solar Array Drive Mechanism (SADM) and Antenna Pointing Mechanism (APM). Longer lifetime (up to 7- 10 years) is becoming a new driver for the coming missions and contact technology sensors often incur in limitations due to the wear of the contacting parts [1].A Self-Compensating Absolute Angular Encoder was developed and tested in the frame of an ESA's ARTES 5.2 project, named INCAS (INnovative Contact-less Angular Sensor). More in particular, the INCAS sensor addresses a market need for contactless angular sensors aimed at replacing the more conventional rotary potentiometers, while featuring the same level of accuracy performances and extending the expected lifetime.

Les Noyaux Actifs de Galaxies en interférométrie optique à très longue base - Projet 'OHANA

NASA Astrophysics Data System (ADS)

Woillez, Julien

2003-12-01

Recent progress in sensitivity achieved by the new generation of optical long baseline interfero- meters (VLTI & Keck) allows new fields of astronomy to benefit from very high angular resolution observations at near infrared wavelength. Extragalactic astronomy, through active galactic nuclei observations, is one of those fields. As a preparation to coming active nuclei interferometric observations, I present a toolbox designed for the in- terpretation of the first data, knowing that their amount will stay small at the beginning whereas the observed objects are known to be complex. I will also present one of the two first observations of active nuclei : the Seyfert 2 nucleus NGC 1068 observed with MIDI, the newly commissioned 10 μm instrument of the VLTI. With the Seyfert 1 nucleus NGC 4151 by Keck interferometer, those two observations confirm the forecasted need of higher angular resolution to study the inner parts of the molecular torus found in active galactic nuclei. The broad line region will be one of the next components to be observed with an interferometer, provided that the extra angular resolution becomes available. In order to study the 3D structure of the region, I present an innovative tomographic technique based on reverberation mapping and interferometry : interferometric reverberation. The 'OHANA project (Optical Hawaiian Array for Nanoradion Astronomy) is the topic of the second part of this work as it will provide the extra angular resolution. The project also aims at demonstrating the use of single mode fibers in J, H and K bands to coherently combine adaptive corrected telescopes, already present on top of Mauna Kea, into a very sensitive and resolving interferometer. I present the preparatory phase of the project (Phase I) where the coupling between adaptive optics and single mode fibers is studied on CFHT, Gemini and Keck telescopes. Those tests allow me to confirm the sensitivity of the final instrument as well as to propose a diagnostic on the different adaptive optics systems. Then I present the 'OHANA beam combiner that is about to be used in the demonstration phase (phase II). This combiner is based on a new concept where the two interferometric outputs of a single mode coaxial combination are combined in a multiaxial scheme in order to obtain a single output, with only one coupler. The interferogram is then temporally coded and the photometry spatially. I present the ongoing developments of pahse II, namely a gaussian beam delay line and 2×300 m long single mode fibers, in J, H and K bands, used for the coherent transport.

A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils

PubMed Central

Li, Jian; Wu, Dan; Han, Yan

2016-01-01

Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent “I-shape” is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation. PMID:27706039

Goal-based angular adaptivity applied to a wavelet-based discretisation of the neutral particle transport equation

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

Goffin, Mark A., E-mail: mark.a.goffin@gmail.com; Buchan, Andrew G.; Dargaville, Steven

2015-01-15

A method for applying goal-based adaptive methods to the angular resolution of the neutral particle transport equation is presented. The methods are applied to an octahedral wavelet discretisation of the spherical angular domain which allows for anisotropic resolution. The angular resolution is adapted across both the spatial and energy dimensions. The spatial domain is discretised using an inner-element sub-grid scale finite element method. The goal-based adaptive methods optimise the angular discretisation to minimise the error in a specific functional of the solution. The goal-based error estimators require the solution of an adjoint system to determine the importance to the specifiedmore » functional. The error estimators and the novel methods to calculate them are described. Several examples are presented to demonstrate the effectiveness of the methods. It is shown that the methods can significantly reduce the number of unknowns and computational time required to obtain a given error. The novelty of the work is the use of goal-based adaptive methods to obtain anisotropic resolution in the angular domain for solving the transport equation. -- Highlights: •Wavelet angular discretisation used to solve transport equation. •Adaptive method developed for the wavelet discretisation. •Anisotropic angular resolution demonstrated through the adaptive method. •Adaptive method provides improvements in computational efficiency.« less

A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils.

PubMed

Li, Jian; Wu, Dan; Han, Yan

2016-09-30

Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent "I-shape" is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation.

Stunted accretion growth of black holes by combined effect of the flow angular momentum and radiation feedback

NASA Astrophysics Data System (ADS)

Sugimura, Kazuyuki; Hosokawa, Takashi; Yajima, Hidenobu; Inayoshi, Kohei; Omukai, Kazuyuki

2018-05-01

Accretion on to seed black holes (BHs) is believed to play a crucial role in formation of supermassive BHs observed at high-redshift (z > 6). Here, we investigate the combined effect of gas angular momentum and radiation feedback on the accretion flow, by performing 2D axially symmetric radiation hydrodynamics simulations that solve the flow structure across the Bondi radius and the outer part of the accretion disc simultaneously. The accreting gas with finite angular momentum forms a rotationally-supported disc inside the Bondi radius, where the accretion proceeds by the angular momentum transport due to assumed α-type viscosity. We find that the interplay of radiation and angular momentum significantly suppresses accretion even if the radiative feedback is weakened in an equatorial shadowing region. The accretion rate is O(α) ˜ O(0.01 - 0.1) times the Bondi value, where α is the viscosity parameter. By developing an analytical model, we show that such a great reduction of the accretion rate persists unless the angular momentum is so small that the corresponding centrifugal radius is ≲ 0.04 times the Bondi radius. We argue that BHs are hard to grow quickly via rapid mass accretion considering the angular momentum barrier presented in this paper.

Satellite angular velocity estimation based on star images and optical flow techniques.

PubMed

Fasano, Giancarmine; Rufino, Giancarlo; Accardo, Domenico; Grassi, Michele

2013-09-25

An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares method are then used to estimate the angular velocity vector components in the sensor rotating frame. A theoretical error budget is developed to estimate the expected angular rate accuracy as a function of camera parameters and star distribution in the field of view. The effectiveness of the proposed technique is tested by using star field scenes generated by a hardware-in-the-loop testing facility and acquired by a commercial-off-the shelf camera sensor. Simulated cases comprise rotations at different rates. Experimental results are presented which are consistent with theoretical estimates. In particular, very accurate angular velocity estimates are generated at lower slew rates, while in all cases the achievable accuracy in the estimation of the angular velocity component along boresight is about one order of magnitude worse than the other two components.

Satellite Angular Velocity Estimation Based on Star Images and Optical Flow Techniques

PubMed Central

Fasano, Giancarmine; Rufino, Giancarlo; Accardo, Domenico; Grassi, Michele

2013-01-01

An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares method are then used to estimate the angular velocity vector components in the sensor rotating frame. A theoretical error budget is developed to estimate the expected angular rate accuracy as a function of camera parameters and star distribution in the field of view. The effectiveness of the proposed technique is tested by using star field scenes generated by a hardware-in-the-loop testing facility and acquired by a commercial-off-the shelf camera sensor. Simulated cases comprise rotations at different rates. Experimental results are presented which are consistent with theoretical estimates. In particular, very accurate angular velocity estimates are generated at lower slew rates, while in all cases the achievable accuracy in the estimation of the angular velocity component along boresight is about one order of magnitude worse than the other two components. PMID:24072023

Rotational velocities of newly discovered, low-mass members of the Alpha Persei cluster

NASA Technical Reports Server (NTRS)

Stauffer, John R.; Hartmann, Lee W.; Jones, Burton F.

1989-01-01

About 30 new, low-mass members of the young open cluster Alpha Persei are identified via a proper-motion study and subsequent photometric and spectroscopic observations. Membership in the cluster is confirmed for a number of the fainter proper-motion candidates from Heckman, Dieckvoss, and Kox (1956). Coordinates, finding charts, BVRI photometry, and rotational velocities are provided for most of the stars. At least two of the stars show peculiar H-alpha emission profiles, with weak but very broad emission wings, and relatively narrow absorption reversals. The rotational velocity distribution for low-mass stars in the Alpha Per cluster are compared with recently derived rotational velocity distributions for T Tauri stars, placing strong constraints on the mechanisms for angular momentum loss during pre-main-sequence evolution.

Conversion-electron spectroscopy and gamma-gamma angular correlation measurements in 116Sn

NASA Astrophysics Data System (ADS)

Cross, D. S.; Pore, J. L.; Andreoiu, C.; Ball, G. C.; Bender, P. C.; Chester, A. S.; Churchman, R.; Demand, G. A.; Diaz Varela, A.; Dunlop, R.; Garnsworthy, A. B.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Jigmeddorj, B.; Laffoley, A. T.; Liblong, A.; Kanungo, R.; Miller, D. T.; Noakes, B.; Petrache, C. M.; Starosta, K.; Svensson, C. E.; Voss, P.; Wang, Z.-M.; Wilson, J. M.; Wood, J. L.; Yates, S. W.

2017-11-01

The 116Sn nucleus was studied via the β- decay of 116In utilizing the 8π spectrometer and its auxiliary detectors at TRIUMF-ISAC. The resulting K-shell conversion coefficients, K/L ratios, and multipole mixing ratios are presented. The 23+ → 21+ 931 keV and 22+ → 21+ 819 keV transition mixing ratios were re-measured and found to be δ = +1.8_{-0.5}^{+0.7} and -1.83(8), respectively. Newly measured mixing ratios for transitions among the low-lying I^{π} = 4+ states in 116Sn, when combined with γ-ray intensity data, suggest that the 2529 keV 42+ state possesses a neutron broken-pair admixture in addition to its dominant proton 2p-2h component.

Evidence of Soft Dipole Resonance in Li 11 with Isoscalar Character

NASA Astrophysics Data System (ADS)

Kanungo, R.; Sanetullaev, A.; Tanaka, J.; Ishimoto, S.; Hagen, G.; Myo, T.; Suzuki, T.; Andreoiu, C.; Bender, P.; Chen, A. A.; Davids, B.; Fallis, J.; Fortin, J. P.; Galinski, N.; Gallant, A. T.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Jansen, G.; Keefe, M.; Krücken, R.; Lighthall, J.; McNeice, E.; Miller, D.; Otsuka, T.; Purcell, J.; Randhawa, J. S.; Roger, T.; Rojas, A.; Savajols, H.; Shotter, A.; Tanihata, I.; Thompson, I. J.; Unsworth, C.; Voss, P.; Wang, Z.

2015-05-01

The first conclusive evidence of a dipole resonance in Li 11 having isoscalar character observed from inelastic scattering with a novel solid deuteron target is reported. The experiment was performed at the newly commissioned IRIS facility at TRIUMF. The results show a resonance peak at an excitation energy of 1.03 ±0.03 MeV with a width of 0.51 ±0.11 MeV (FWHM). The angular distribution is consistent with a dipole excitation in the distorted-wave Born approximation framework. The observed resonance energy together with shell model calculations show the first signature that the monopole tensor interaction is important in Li 11 . The first ab initio calculations in the coupled cluster framework are also presented.

10,11 B(α,n) 13 , 14N cross section measurements

NASA Astrophysics Data System (ADS)

Liu, Qian; Michael, Febbraro; Deboer, Richard; Michael, Wiescher

2017-09-01

10,11 B(α,n) 13 , 14N have been identified as possible background sources for underground experiments at low Eα energy. These reactions have been studied at University of Notre Dame's Nuclear Science Laboratory using Santa Anna 5 MV accelerator. 11B(α,n)14N was measured with a 3He counter, and a good R-matrix fit was obtained, which shows our data in agreement with other published data. Measurement of 10B(α,n)13N was performed down to Eα = 0.57 MeV, with two deuterated liquid scintillators, EJ315 and EJ301D, and with the help of unfolding technique, neutron energy information can be extracted. EJ301D is a newly-developed neutron detector, with better pulse shape discrimination, and has been used to do angular distribution measurements. Additionally, the (α ,α1 γ) and (n , pγ) channels have been monitored independently by observation of 718keV γ transition in 10B and 3853keV γ transition in 13C. Preliminary analysis indicates the discovery of a new resonance in low energy region. Research supported by NSF PHY-1430152, and JINA PHY-1419765.

Sentence processing in the cerebral cortex.

PubMed

Sakai, K L; Hashimoto, R; Homae, F

2001-01-01

Human language is a unique faculty of the mind. It has been the ultimate mystery throughout the history of neuroscience. Despite many aphasia and functional imaging studies, the exact correlation between cortical language areas and subcomponents of the linguistic system has not been established. One notable drawback is that most functional imaging studies have tested language tasks at the word level, such as lexical decision and word generation tasks, thereby neglecting the syntactic aspects of the language faculty. As proposed by Chomsky, the critical knowledge of language involves universal grammar (UG), which governs the syntactic structure of sentences. In this article, we will review recent advances made by functional neuroimaging studies of language, focusing especially on sentence processing in the cerebral cortex. We also present the recent results of our functional magnetic resonance imaging (fMRI) study intended to identify cortical areas specifically involved in syntactic processing. A study of sentence processing that employs a newly developed technique, optical topography (OT), is also presented. Based on these findings, we propose a modular specialization of Broca's area, Wernicke's area, and the angular gyrus/supramarginal gyrus. The current direction of research in neuroscience is beginning to establish the existence of distinct modules responsible for our knowledge of language.

A high precision instrument to measure angular and binocular deviation introduced by aircraft windscreens by using a shadow casting technique

NASA Astrophysics Data System (ADS)

Shivananju, B. N.; Yamdagni, S.; Vasu, R. M.; Asokan, S.

2012-12-01

Objects viewed through transparent sheets with residual non-parallelism and irregularity appear shifted and distorted. This distortion is measured in terms of angular and binocular deviation of an object viewed through the transparent sheet. The angular and binocular deviations introduced are particularly important in the context of aircraft windscreens and canopies as they can interfere with decision making of pilots especially while landing, leading to accidents. In this work, we have developed an instrument to measure both the angular and binocular deviations introduced by transparent sheets. This instrument is especially useful in the qualification of aircraft windscreens and canopies. It measures the deviation in the geometrical shadow cast by a periodic dot pattern trans-illuminated by the distorted light beam from the transparent test specimen compared to the reference pattern. Accurate quantification of the shift in the pattern is obtained by cross-correlating the reference shadow pattern with the specimen shadow pattern and measuring the location of the correlation peak. The developed instrument is handy to use and computes both angular and binocular deviation with an accuracy of less than ±0.1 mrad (≈0.036 mrad) and has an excellent repeatability with an error of less than 2%.

Improving Student Understanding of Addition of Angular Momentum in Quantum Mechanics

ERIC Educational Resources Information Center

Zhu, Guangtian; Singh, Chandralekha

2013-01-01

We describe the difficulties advanced undergraduate and graduate students have with concepts related to addition of angular momentum in quantum mechanics. We also describe the development and implementation of a research-based learning tool, Quantum Interactive Learning Tutorial (QuILT), to reduce these difficulties. The preliminary evaluation…

Design and Analysis of an Axisymmetric Phased Array Fed Gregorian Reflector System for Limited Scanning

DTIC Science & Technology

2016-01-22

applications. For space applications, attitude control systems can provide good angular control of the antenna aperture with small residual angular...Bilyeu, and G.R. Veal, Development of Flight Hardware for a Large Inflatable- Deployable Antenna Experiment , Acta Astronautica, Vol. 38, Nos. 4-8

High accuracy fuel flowmeter

NASA Technical Reports Server (NTRS)

1986-01-01

All three flowmeter concepts (vortex, dual turbine, and angular momentum) were subjected to experimental and analytical investigation to determine the potential portotype performance. The three concepts were subjected to a comprehensive rating. Eight parameters of performance were evaluated on a zero-to-ten scale, weighted, and summed. The relative ratings of the vortex, dual turbine, and angular momentum flowmeters are 0.71, 1.00, and 0.95, respectively. The dual turbine flowmeter concept was selected as the primary candidate and the angular momentum flowmeter as the secondary candidate for prototype development and evaluation.

Systemic regulation of leaf anatomical structure, photosynthetic performance, and high-light tolerance in sorghum.

PubMed

Jiang, Chuang-Dao; Wang, Xin; Gao, Hui-Yuan; Shi, Lei; Chow, Wah Soon

2011-03-01

Leaf anatomy of C3 plants is mainly regulated by a systemic irradiance signal. Since the anatomical features of C4 plants are different from that of C3 plants, we investigated whether the systemic irradiance signal regulates leaf anatomical structure and photosynthetic performance in sorghum (Sorghum bicolor), a C4 plant. Compared with growth under ambient conditions (A), no significant changes in anatomical structure were observed in newly developed leaves by shading young leaves alone (YS). Shading mature leaves (MS) or whole plants (S), on the other hand, caused shade-leaf anatomy in newly developed leaves. By contrast, chloroplast ultrastructure in developing leaves depended only on their local light conditions. Functionally, shading young leaves alone had little effect on their net photosynthetic capacity and stomatal conductance, but shading mature leaves or whole plants significantly decreased these two parameters in newly developed leaves. Specifically, the net photosynthetic rate in newly developed leaves exhibited a positive linear correlation with that of mature leaves, as did stomatal conductance. In MS and S treatments, newly developed leaves exhibited severe photoinhibition under high light. By contrast, newly developed leaves in A and YS treatments were more resistant to high light relative to those in MS- and S-treated seedlings. We suggest that (1) leaf anatomical structure, photosynthetic capacity, and high-light tolerance in newly developed sorghum leaves were regulated by a systemic irradiance signal from mature leaves; and (2) chloroplast ultrastructure only weakly influenced the development of photosynthetic capacity and high-light tolerance. The potential significance of the regulation by a systemic irradiance signal is discussed.

Development of a High Angular Resolution Diffusion Imaging Human Brain Template

PubMed Central

Varentsova, Anna; Zhang, Shengwei; Arfanakis, Konstantinos

2014-01-01

Brain diffusion templates contain rich information about the microstructure of the brain, and are used as references in spatial normalization or in the development of brain atlases. The accuracy of diffusion templates constructed based on the diffusion tensor (DT) model is limited in regions with complex neuronal micro-architecture. High angular resolution diffusion imaging (HARDI) overcomes limitations of the DT model and is capable of resolving intravoxel heterogeneity. However, when HARDI is combined with multiple-shot sequences to minimize image artifacts, the scan time becomes inappropriate for human brain imaging. In this work, an artifact-free HARDI template of the human brain was developed from low angular resolution multiple-shot diffusion data. The resulting HARDI template was produced in ICBM-152 space based on Turboprop diffusion data, was shown to resolve complex neuronal micro-architecture in regions with intravoxel heterogeneity, and contained fiber orientation information consistent with known human brain anatomy. PMID:24440528

Angular photogrammetric analysis of the soft tissue profile in 12-year-old southern Chinese.

PubMed

Leung, Cindi Sy; Yang, Yanqi; Wong, Ricky Wk; Hägg, Urban; Lo, John; McGrath, Colman

2014-12-24

To quantify average angular measurements that define the soft tissue profiles of 12-year-old southern Chinese and to determine gender differences. A random population sample of 514 12-year-old children was recruited (about 10% of a Hong Kong Chinese birth cohort). Photographs were taken in natural head posture and 12 soft tissue landmarks were located on the photos to measure 12 angular measurements using ImageJ (V1.45s) for Windows. Approximately 10% of photographs were reanalyzed and method error was calculated. Angular norm values for the 12 parameters were determined and gender differences were assessed using 2 sample T-test with 95% confidence interval. The response rate was 54.1% (278/514). Norm values for the 12 angular measurements were generated. The greatest variability was found for the nasolabial (Cm-Sn-Ls) and labiomental (Li-Sm-Pg) angles. Gender differences were found in 4 angular parameters: vertical nasal angle (N-Prn/TV) (p < 0.05), cervicomental angle (G-Pg/C-Me) (p < 0.001), facial convexity angle (G-Sn-Pg) (p < 0.01) and total facial convexity angle (G-Prn-Pg)(p < 0.01). Norm values for 12 angular measurements among 12-year-old southern Chinese children were provided and some variability noted. Gender differences were apparent in several angular measurements. This study has implications in developing norm values for southern Chinese and for comparison with other ethnic groups.

Angular momentum transport with twisted exciton wave packets

NASA Astrophysics Data System (ADS)

Zang, Xiaoning; Lusk, Mark T.

2017-10-01

A chain of cofacial molecules with CN or CN h symmetry supports excitonic states with a screwlike structure. These can be quantified with the combination of an axial wave number and an azimuthal winding number. Combinations of these states can be used to construct excitonic wave packets that spiral down the chain with well-determined linear and angular momenta. These twisted exciton wave packets can be created and annihilated using laser pulses, and their angular momentum can be optically modified during transit. This allows for the creation of optoexcitonic circuits in which information, encoded in the angular momentum of light, is converted into excitonic wave packets that can be manipulated, transported, and then reemitted. A tight-binding paradigm is used to demonstrate the key ideas. The approach is then extended to quantify the evolution of twisted exciton wave packets in a many-body, multilevel time-domain density functional theory setting. In both settings, numerical methods are developed that allow the site-to-site transfer of angular momentum to be quantified.

Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

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

Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over themore » array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.« less

A study of angular dependence in the ablation rate of polymers by nanosecond pulses

NASA Astrophysics Data System (ADS)

Pedder, James E. A.; Holmes, Andrew S.

2006-02-01

Measurements of ablation rate have traditionally been carried out only at normal incidence. However, in real-world applications ablation is often carried out at oblique angles, and it is useful to have prior knowledge of the ablation rate in this case. Detailed information about the angular dependence is also important for the development of ablation simulation tools, and can provide additional insight into the ablation mechanism. Previously we have reported on the angular dependence of direct-write ablation at 266 nm wavelength in solgel and polymer materials. In this paper we present a systematic study of angular dependence for excimer laser ablation of two polymer materials of interest for microfabrication: polycarbonate and SU8 photoresist. The results are used to improve simulation models to aid in mask design.

Mass loss of stars on the asymptotic giant branch. Mechanisms, models and measurements

NASA Astrophysics Data System (ADS)

Höfner, Susanne; Olofsson, Hans

2018-01-01

As low- and intermediate-mass stars reach the asymptotic giant branch (AGB), they have developed into intriguing and complex objects that are major players in the cosmic gas/dust cycle. At this stage, their appearance and evolution are strongly affected by a range of dynamical processes. Large-scale convective flows bring newly-formed chemical elements to the stellar surface and, together with pulsations, they trigger shock waves in the extended stellar atmosphere. There, massive outflows of gas and dust have their origin, which enrich the interstellar medium and, eventually, lead to a transformation of the cool luminous giants into white dwarfs. Dust grains forming in the upper atmospheric layers play a critical role in the wind acceleration process, by scattering and absorbing stellar photons and transferring their outward-directed momentum to the surrounding gas through collisions. Recent progress in high-angular-resolution instrumentation, from the visual to the radio regime, is leading to valuable new insights into the complex dynamical atmospheres of AGB stars and their wind-forming regions. Observations are revealing asymmetries and inhomogeneities in the photospheric and dust-forming layers which vary on time-scales of months, as well as more long-lived large-scale structures in the circumstellar envelopes. High-angular-resolution observations indicate at what distances from the stars dust condensation occurs, and they give information on the chemical composition and sizes of dust grains in the close vicinity of cool giants. These are essential constraints for building realistic models of wind acceleration and developing a predictive theory of mass loss for AGB stars, which is a crucial ingredient of stellar and galactic chemical evolution models. At present, it is still not fully possible to model all these phenomena from first principles, and to predict the mass-loss rate based on fundamental stellar parameters only. However, much progress has been made in recent years, which is described in this review. We complement this by discussing how observations of emission from circumstellar molecules and dust can be used to estimate the characteristics of the mass loss along the AGB, and in different environments. We also briefly touch upon the issue of binarity.

Sensor Data Quality and Angular Rate Down-Selection Algorithms on SLS EM-1

NASA Technical Reports Server (NTRS)

Park, Thomas; Oliver, Emerson; Smith, Austin

2018-01-01

The NASA Space Launch System Block 1 launch vehicle is equipped with an Inertial Navigation System (INS) and multiple Rate Gyro Assemblies (RGA) that are used in the Guidance, Navigation, and Control (GN&C) algorithms. The INS provides the inertial position, velocity, and attitude of the vehicle along with both angular rate and specific force measurements. Additionally, multiple sets of co-located rate gyros supply angular rate data. The collection of angular rate data, taken along the launch vehicle, is used to separate out vehicle motion from flexible body dynamics. Since the system architecture uses redundant sensors, the capability was developed to evaluate the health (or validity) of the independent measurements. A suite of Sensor Data Quality (SDQ) algorithms is responsible for assessing the angular rate data from the redundant sensors. When failures are detected, SDQ will take the appropriate action and disqualify or remove faulted sensors from forward processing. Additionally, the SDQ algorithms contain logic for down-selecting the angular rate data used by the GN&C software from the set of healthy measurements. This paper provides an overview of the algorithms used for both fault-detection and measurement down selection.

Observed Hierarchy of Student Proficiency with Period, Frequency, and Angular Frequency

ERIC Educational Resources Information Center

Young, Nicholas T.; Heckler, Andrew F.

2018-01-01

In the context of a generic harmonic oscillator, we investigated students' accuracy in determining the period, frequency, and angular frequency from mathematical and graphical representations. In a series of studies including interviews, free response tests, and multiple-choice tests developed in an iterative process, we assessed students in both…

New optical and radio frequency angular tropospheric refraction models for deep space applications

NASA Technical Reports Server (NTRS)

Berman, A. L.; Rockwell, S. T.

1976-01-01

The development of angular tropospheric refraction models for optical and radio frequency usage is presented. The models are compact analytic functions, finite over the entire domain of elevation angle, and accurate over large ranges of pressure, temperature, and relative humidity. Additionally, FORTRAN subroutines for each of the models are included.

Obtaining the Electron Angular Momentum Coupling Spectroscopic Terms, jj

ERIC Educational Resources Information Center

Orofino, Hugo; Faria, Roberto B.

2010-01-01

A systematic procedure is developed to obtain the electron angular momentum coupling (jj) spectroscopic terms, which is based on building microstates in which each individual electron is placed in a different m[subscript j] "orbital". This approach is similar to that used to obtain the spectroscopic terms under the Russell-Saunders (LS) coupling…

Rotational study of the NH{sub 3}–CO complex: Millimeter-wave measurements and ab initio calculations

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

Surin, L. A., E-mail: surin@ph1.uni-koeln.de; Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow; Potapov, A.

2015-03-21

The rotational spectrum of the van der Waals complex NH{sub 3}–CO has been measured with the intracavity OROTRON jet spectrometer in the frequency range of 112–139 GHz. Newly observed and assigned transitions belong to the K = 0–0, K = 1–1, K = 1–0, and K = 2–1 subbands correlating with the rotationless (j{sub k}){sub NH3} = 0{sub 0} ground state of free ortho-NH{sub 3} and the K = 0–1 and K = 2–1 subbands correlating with the (j{sub k}){sub NH3} = 1{sub 1} ground state of free para-NH{sub 3}. The (approximate) quantum number K is the projection of themore » total angular momentum J on the intermolecular axis. Some of these transitions are continuations to higher J values of transition series observed previously [C. Xia et al., Mol. Phys. 99, 643 (2001)], the other transitions constitute newly detected subbands. The new data were analyzed together with the known millimeter-wave and microwave transitions in order to determine the molecular parameters of the ortho-NH{sub 3}–CO and para-NH{sub 3}–CO complexes. Accompanying ab initio calculations of the intermolecular potential energy surface (PES) of NH{sub 3}–CO has been carried out at the explicitly correlated coupled cluster level of theory with single, double, and perturbative triple excitations and an augmented correlation-consistent triple zeta basis set. The global minimum of the five-dimensional PES corresponds to an approximately T-shaped structure with the N atom closest to the CO subunit and binding energy D{sub e} = 359.21 cm{sup −1}. The bound rovibrational levels of the NH{sub 3}–CO complex were calculated for total angular momentum J = 0–6 on this intermolecular potential surface and compared with the experimental results. The calculated dissociation energies D{sub 0} are 210.43 and 218.66 cm{sup −1} for ortho-NH{sub 3}–CO and para-NH{sub 3}–CO, respectively.« less

Temporal Evolution of Spectral and Angular Characteristics of SEP Particles during Several GLEs of Solar Cycle 23 Derived from NM Data

NASA Astrophysics Data System (ADS)

Mishev, Alexander; Usoskin, Ilya; Kocharov, Leon

High-energy charged particles of solar origin could represent a severe radiation risk for astronauts and air crew. In addition, they could disrupt technological systems. When a ground-based neutron monitor register abrupt increases in solar energetic particles (SEPs), we observe a special case of solar energetic particle event, a ground-level enhancement (GLE). In order to derive the spectral and angular characteristics of GLE particles a precise computation of solar energetic particle propagation in the Earth's magnetosphere and atmosphere is necessary. It consists of detailed computation of assymptotic cones for neutron monitors (NMs) and application of inverse method using the newly computed neutron monitor yield function. Assymptotic directions are computed using the Planetocosmics code and realistic magnetospheric models, namely IGRF as the internal model and Tsyganenko 89 with the corresponding Kp index as the external one. The inverse problem solution is performed on the basis of non-linear least squares method, namely Levenberg-Marqurdt. In the study presented here, we analyse several major GLEs of the solar cycle 23 as well as the first GLE event of the solar cycle 24, namely GLE69, GLE70 and GLE 71. The SEP spectra and pitch angle distribution are obtained at different momenta since the event's onset. The obtained characteristics are compared with previously reported results. The obtained results are briefly discussed.

Magnetic alloy nanowire arrays with different lengths: Insights into the crossover angle of magnetization reversal process

NASA Astrophysics Data System (ADS)

Samanifar, S.; Alikhani, M.; Almasi Kashi, M.; Ramazani, A.; Montazer, A. H.

2017-05-01

Nanoscale magnetic alloy wires are being actively investigated, providing fundamental insights into tuning properties in magnetic data storage and processing technologies. However, previous studies give trivial information about the crossover angle of magnetization reversal process in alloy nanowires (NWs). Here, magnetic alloy NW arrays with different compositions, composed of Fe, Co and Ni have been electrochemically deposited into hard-anodic aluminum oxide templates with a pore diameter of approximately 150 nm. Under optimized conditions of alumina barrier layer and deposition bath concentrations, the resulting alloy NWs with aspect ratio and saturation magnetization (Ms) up to 550 and 1900 emu cm-3, respectively, are systematically investigated in terms of composition, crystalline structure and magnetic properties. Using angular dependence of coercivity extracted from hysteresis loops, the reversal processes are evaluated, indicating non-monotonic behavior. The crossover angle (θc) is found to depend on NW length and Ms. At a constant Ms, increasing NW length decreases θc, thereby decreasing the involvement of vortex mode during the magnetization reversal process. On the other hand, decreasing Ms decreases θc in large aspect ratio (>300) alloy NWs. Phenomenologically, it is newly found that increasing Ni content in the composition decreases θc. The angular first-order reversal curve (AFORC) measurements including the irreversibility of magnetization are also investigated to gain a more detailed insight into θc.

Correlations between Angular Velocities in Selected Joints and Velocity of Table Tennis Racket during Topspin Forehand and Backhand

PubMed Central

Bańkosz, Ziemowit; Winiarski, Sławomir

2018-01-01

The aim of this study was to determine the correlations between angular velocities in individual joints and racket velocity for different topspin forehand and backhand strokes in table tennis. Ten elite female table tennis players participated, presenting different kinds of topspin forehands and backhands – after a no-spin ball (FH1, BH1), after a backspin ball (FH2, BH2) and “heavy” topspin (FH3, BH3). Range of motion was measured with the BTS Smart-E (BTS Bioengineering, Milan, Italy) motion analysis system with a specially developed marker placement protocol for the upper body parts and an acoustic sensor attached to the racket to identify ball-racket contact. In forehand strokes angular velocities of internal arm rotation and adduction in shoulder joint correlated with racket velocity. Racket velocity was correlated with angular velocities (hip extension on the playing side; hip flexion on the opposite side; ankle flexion) in the case of a topspin forehand performed with maximal force –”heavy” topspin (FH3). In backhand strokes the velocities of arm abduction and shoulder girdle rotation towards the playing side correlated with racket velocity. The angular velocity of internal arm rotation and adduction in shoulder joint may be important components of a coordinated stroke, whilst angular velocity can substantially affect the racket speed when one is changing the type of stroke. Key points The aim of this study was to calculate correlations between racket velocity and the angular velocities of individual joints and for variants of topspin forehand and backhand strokes in table tennis. A novel model was used to estimate range of motion (specially developed placement protocol for upper body markers and identification of a ball-racket contact using an acoustic sensor attached to the racket). In forehand strokes angular velocities of internal arm rotation and adduction in shoulder joint were correlated with racket velocity. Correlations between racket velocity and the angular velocities of playing- and non-playing-side hip extension and ankle flexion were found in topspin forehands. In topspin backhands abduction of the arm had the greatest impact on the racket speed. The results can be used directly to improve training of table tennis techniques, especially topspin strokes. PMID:29769835

The Properties of the Diffuse X-ray Background from the DXL sounding rocket mission (plus ROSAT, XMM-Newton and Suzaku data)

NASA Astrophysics Data System (ADS)

Galeazzi, Massimiliano

2017-08-01

Understanding the properties of the different components of the Diffuse X-ray Background (DXB) is made particularly difficult by their similar spectral signature.The University of Miami has been working on disentangling the different DXB components for many years, using a combination of proprietary and archival data from XMM-Newton, Suzaku, and Chandra, and a sounding rocket mission (DXL) specifically designed to study the properties of Local Hot Bubble (LHB) and Solar Wind Charge eXchange (SWCX) using their spatial signature. In this talk we will present:(a) Results from the DXL mission, specifically launch #2, to study the properties of the SWCX and LHB (and GH) and their contribution to the ROSAT All Sky Survey Bands(b) Results from a Suzaku key project to characterize the SWCX and build a semi-empirical model to predict the SWCX line emission for any time, any direction. A publicly available web portal for the model will go online by the end of the year(c) Results from XMM-Newton deep surveys to study the angular correlation of the Warm-Hot Intergalactic Medium (WHIM) in the direction of the Chandra Deep Field South.DXL launch #3, schedule for January 2018 and the development of the DXG sounding rocket mission to characterize the GH-CGM emission using newly developed micropore optics will also be discussed.

On the Cause of Geodetic Satellite Accelerations and Other Correlated Unmodeled Phenomena

NASA Astrophysics Data System (ADS)

Mayer, A. F.

2005-12-01

An oversight in the development of the Einstein field equations requires a well-defined amendment to general relativity that very slightly modifies the weak-field Schwarzschild geometry yielding unambiguous new predictions of gravitational relativistic phenomena. The secular accelerations of LAGEOS, Etalon and other geodetic satellites are definitively explained as a previously unmodeled relativistic effect of the gravitational field. Observed dynamic variations may be correlated to the complex dynamic relationship between the satellite angular momentum vector and the solar gravitational gradient associated with the orbital motion of the Earth and the natural precession of the satellite orbit. The Pioneer Anomaly, semidiurnal saw-toothed pseudo-range residuals of GPS satellites, peculiar results of radio occultation experiments, secular accelerations of Solar System moons, the conspicuous excess redshift of white dwarf stars and other documented empirical observations are all correlated to the same newly modeled subtle relativistic energy effect. Modern challenges in the determination and maintenance of an accurate and reliable terrestrial reference frame, difficulties with global time synchronization at nanosecond resolution and the purported existence of unlikely excessive undulations of the Geoid relative to the Ellipsoid are all related to this previously unknown phenomenon inherent to the gravitational field. Doppler satellite measurements made by the TRANSIT system (the precursor to GPS) were significantly affected; WGS 84 coordinates and other geodetic data now assumed to be correct to high accuracy require correction based on the new theoretical developments.

Decreased resting-state interhemispheric functional connectivity in unaffected siblings of schizophrenia patients.

PubMed

Guo, Wenbin; Jiang, Jiajing; Xiao, Changqing; Zhang, Zhikun; Zhang, Jian; Yu, Liuyu; Liu, Jianrong; Liu, Guiying

2014-01-01

Neuroimaging studies in unaffected siblings of schizophrenia patients can provide clues to the pathophysiology for the development of schizophrenia. However, little is known about the alterations of the interhemispheric resting-state functional connectivity (FC) in siblings, although the dysconnectivity hypothesis is prevailing in schizophrenia for years. In the present study, we used a newly validated voxel-mirrored homotopic connectivity (VMHC) method to identify whether aberrant interhemispheric FC was present in unaffected siblings at increased risk of developing schizophrenia at rest. Forty-six unaffected siblings of schizophrenia patients and 50 age-, sex-, and education-matched healthy controls underwent a resting-state functional magnetic resonance imaging (fMRI). Automated VMHC was used to analyze the data. The sibling group had lower VMHC than the control group in the angular gyrus (AG) and the lingual gyrus/cerebellum lobule VI. No region exhibited higher VMHC in the sibling group than in the control group. There was no significant sex difference of the VMHC values between male siblings and female siblings or between male controls and female controls, although evidence has been accumulated that size and shape of the corpus callosum, and functional homotopy differ between men and women. Our results first suggest that interhemispheric resting-state FC of VMHC is disrupted in unaffected siblings of schizophrenia patients, and add a new clue of abnormal interhemispheric resting-state FC to the pathophysiology for the development of schizophrenia. Copyright © 2013 Elsevier B.V. All rights reserved.

ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS

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

Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M., E-mail: rrr@astro.princeton.edu

The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification ofmore » three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.« less

Angular Impact Mitigation System for Bicycle Helmets to Reduce Head Acceleration and Risk of Traumatic Brain Injury

PubMed Central

Hansen, Kirk; Dau, Nathan; Feist, Florian; Deck, Caroline; Willinger, Rémy; Madey, Steven M.; Bottlang, Michael

2013-01-01

Angular acceleration of the head is a known cause of traumatic brain injury (TBI), but contemporary bicycle helmets lack dedicated mechanisms to mitigate angular acceleration. A novel Angular Impact Mitigation (AIM) system for bicycle helmets has been developed that employs an elastically suspended aluminum honeycomb liner to absorb linear acceleration in normal impacts as well as angular acceleration in oblique impacts. This study tested bicycle helmets with and without AIM technology to comparatively assess impact mitigation. Normal impact tests were performed to measure linear head acceleration. Oblique impact tests were performed to measure angular head acceleration and neck loading. Furthermore, acceleration histories of oblique impacts were analyzed in a computational head model to predict the resulting risk of TBI in the form of concussion and diffuse axonal injury (DAI). Compared to standard helmets, AIM helmets resulted in a 14% reduction in peak linear acceleration (p < 0.001), a 34% reduction in peak angular acceleration (p < 0.001), and a 22% to 32% reduction in neck loading (p < 0.001). Computational results predicted that AIM helmets reduced the risk of concussion and DAI by 27% and 44%, respectively. In conclusion, these results demonstrated that AIM technology could effectively improve impact mitigation compared to a contemporary expanded polystyrene-based bicycle helmet, and may enhance prevention of bicycle-related TBI. Further research is required. PMID:23770518

Joint Angular Velocity in Spastic Gait and the Influence of Muscle-Tendon Lengthening*

PubMed Central

GRANATA, KEVIN P.; ABEL, MARK F.; DAMIANO, DIANE L.

2006-01-01

Background Joint angular velocity (the rate of flexion and extension of a joint) is related to the dynamics of muscle activation and force generation during walking. Therefore, the goal of this research was to examine the joint angular velocity in normal and spastic gait and changes resulting from muscle-tendon lengthening (recession and tenotomy) in patients who have spastic cerebral palsy. Methods The gait patterns of forty patients who had been diagnosed with spastic cerebral palsy (mean age, 8.3 years; range, 3.7 to 14.8 years) and of seventy-three age-matched, normally developing subjects were evaluated with three-dimensional motion analysis and electromyography. The patients who had cerebral palsy were evaluated before muscle-tendon lengthening and nine months after treatment. Results The gait patterns of the patients who had cerebral palsy were characterized by increased flexion of the knee in the stance phase, premature plantar flexion of the ankle, and reduced joint angular velocities compared with the patterns of the normally developing subjects. Even though muscle-tendon lengthening altered sagittal joint angles in gait, the joint angular velocities were generally unchanged at the hip and knee. Only the ankle demonstrated modified angular velocities, including reduced dorsiflexion velocity at foot-strike and improved dorsiflexion velocity through midstance, after treatment. Electromyographic changes included reduced amplitude of the gastrocnemius-soleus during the loading phase and decreased knee coactivity (the ratio of quadriceps and hamstring activation) at toe-off. Principal component analyses showed that, compared with joint-angle data, joint angular velocity was better able to discriminate between the gait patterns of the normal and cerebral palsy groups. Conclusions This study showed that muscle-tendon lengthening corrects biomechanical alignment as reflected by changes in sagittal joint angles. However, joint angular velocity and electromyographic data suggest that the underlying neural input remains largely unchanged at the hip and knee. Conversely, electromyographic changes and changes in velocity in the ankle indicate that the activation pattern of the gastrocnemius-soleus complex in response to stretch was altered by recession of the complex. PMID:10682726

Replicated Wolter-I X-ray Optics for Lightweight, High Angular Resolution, Large Collecting Area X-Ray Telescopes

NASA Technical Reports Server (NTRS)

Joy, M.; Bilbro, J.; Elsner, R.; Jones, W.; Kolodziejczak, J.; Petruzzo, J.; ODell, S.; Weisskopf, M.

1997-01-01

The next generation of orbiting x-ray observatories will require high angular resolution telescopes that have an order of magnitude greater collecting area in the 0.1-10 keV spectral region than those currently under construction, but with a much lower weight and cost per unit area. Replicated Wolter-I x-ray optics have the potential to meet this requirement. The currently demonstrated capabilities of replicated Wolter-I optics will be described, and a development plan for creating lightweight, high angular resolution, large effective area x-ray telescopes will be presented.

Towards multi-field D-brane inflation in a warped throat

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

Chen, Heng-Yu; Gong, Jinn-Ouk; Koyama, Kazuya

2010-11-01

We study the inflationary dynamics in a model of slow-roll inflation in warped throat. Inflation is realized by the motion of a D-brane along the radial direction of the throat, and at later stages instabilities develop in the angular directions. We closely investigate both the single field potential relevant for the slow-roll phase, and the full multi-field one including the angular modes which becomes important at later stages. We study the main features of the instability process, discussing its possible consequences and identifying the vacua towards which the angular modes are driven.

Development and validity of methods for the estimation of temporal gait parameters from heel-attached inertial sensors in younger and older adults.

PubMed

Misu, Shogo; Asai, Tsuyoshi; Ono, Rei; Sawa, Ryuichi; Tsutsumimoto, Kota; Ando, Hiroshi; Doi, Takehiko

2017-09-01

The heel is likely a suitable location to which inertial sensors are attached for the detection of gait events. However, there are few studies to detect gait events and determine temporal gait parameters using sensors attached to the heels. We developed two methods to determine temporal gait parameters: detecting heel-contact using acceleration and detecting toe-off using angular velocity data (acceleration-angular velocity method; A-V method), and detecting both heel-contact and toe-off using angular velocity data (angular velocity-angular velocity method; V-V method). The aim of this study was to examine the concurrent validity of the A-V and V-V methods against the standard method, and to compare their accuracy. Temporal gait parameters were measured in 10 younger and 10 older adults. The intra-class correlation coefficients were excellent in both methods compared with the standard method (0.80 to 1.00). The root mean square errors of stance and swing time in the A-V method were smaller than the V-V method in older adults, although there were no significant discrepancies in the other comparisons. Our study suggests that inertial sensors attached to the heels, using the A-V method in particular, provide a valid measurement of temporal gait parameters. Copyright © 2017 Elsevier B.V. All rights reserved.

A methodologic approach for normalizing angular work and velocity during isotonic and isokinetic eccentric training.

PubMed

Guilhem, Gaël; Cornu, Christophe; Guével, Arnaud

2012-01-01

Resistance exercise training commonly is performed against a constant external load (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied. To examine whether the standardization protocol could be adjusted and applied to an eccentric training program. Controlled laboratory study. Controlled research laboratory. Twenty-one sport science male students (age = 20.6 ± 1.5 years, height = 178.0 ± 4.0 cm, mass = 74.5 ± 9.1 kg). Participants performed 9 weeks of isotonic (n = 11) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity. Angular work and angular velocity. The isotonic and isokinetic groups performed the same total amount of work (-185.2 ± 6.5 kJ and -184.4 ± 8.6 kJ, respectively) at the same angular velocity (21 ± 1°/s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training. The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury.

Chiral resolution of spin angular momentum in linearly polarized and unpolarized light

PubMed Central

Hernández, R. J.; Mazzulla, A.; Provenzano, C.; Pagliusi, P.; Cipparrone, G.

2015-01-01

Linearly polarized (LP) and unpolarized (UP) light are racemic entities since they can be described as superposition of opposite circularly polarized (CP) components of equal amplitude. As a consequence they do not carry spin angular momentum. Chiral resolution of a racemate, i.e. separation of their chiral components, is usually performed via asymmetric interaction with a chiral entity. In this paper we provide an experimental evidence of the chiral resolution of linearly polarized and unpolarized Gaussian beams through the transfer of spin angular momentum to chiral microparticles. Due to the interplay between linear and angular momentum exchange, basic manipulation tasks, as trapping, spinning or orbiting of micro-objects, can be performed by light with zero helicity. The results might broaden the perspectives for development of miniaturized and cost-effective devices. PMID:26585284

Three-body Coulomb systems using generalized angular-momentum S states

NASA Technical Reports Server (NTRS)

Whitten, R. C.; Sims, J. S.

1974-01-01

An expansion of the three-body Coulomb potential in generalized angular-momentum eigenfunctions developed earlier by one of the authors is used to compute energy eigenvalues and eigenfunctions of bound S states of three-body Coulomb systems. The results for He, H(-), e(-)e(+)e(-), and pmu(-)p are compared with the results of other computational approaches.

Could SXP 1062 be an Accreting Magnetar?

NASA Astrophysics Data System (ADS)

Fu, Lei; Li, Xiang-Dong

2012-10-01

In this work we explore the possible evolutionary track of the neutron star in the newly discovered Be/X-ray binary SXP 1062, which is believed to be the first X-ray pulsar associated with a supernova remnant. Although no cyclotron feature has been detected to indicate the strength of the neutron star's magnetic field, we show that it may be >~ 1014 G. If so, SXP 1062 may belong to the accreting magnetars in binary systems. We attempt to reconcile the short age and long spin period of the pulsar taking account of different initial parameters and spin-down mechanisms of the neutron star. Our calculated results show that to spin down to a period ~1000 s within 10-40 kyr requires efficient propeller mechanisms. In particular, the model for angular momentum loss under energy conservation seems to be ruled out.

Development of a high angular resolution diffusion imaging human brain template.

PubMed

Varentsova, Anna; Zhang, Shengwei; Arfanakis, Konstantinos

2014-05-01

Brain diffusion templates contain rich information about the microstructure of the brain, and are used as references in spatial normalization or in the development of brain atlases. The accuracy of diffusion templates constructed based on the diffusion tensor (DT) model is limited in regions with complex neuronal micro-architecture. High angular resolution diffusion imaging (HARDI) overcomes limitations of the DT model and is capable of resolving intravoxel heterogeneity. However, when HARDI is combined with multiple-shot sequences to minimize image artifacts, the scan time becomes inappropriate for human brain imaging. In this work, an artifact-free HARDI template of the human brain was developed from low angular resolution multiple-shot diffusion data. The resulting HARDI template was produced in ICBM-152 space based on Turboprop diffusion data, was shown to resolve complex neuronal micro-architecture in regions with intravoxel heterogeneity, and contained fiber orientation information consistent with known human brain anatomy. Copyright © 2014 Elsevier Inc. All rights reserved.

Fast Plasma Instrument for MMS: Simulation Results

NASA Technical Reports Server (NTRS)

Figueroa-Vinas, Adolfo; Adrian, Mark L.; Lobell, James V.; Simpson, David G.; Barrie, Alex; Winkert, George E.; Yeh, Pen-Shu; Moore, Thomas E.

2008-01-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. The Dual Electron Spectrometer (DES) of the Fast Plasma Instrument (FPI) for MMS meets these demanding requirements by acquiring the electron velocity distribution functions (VDFs) for the full sky with high-resolution angular measurements every 30 ms. This will provide unprecedented access to electron scale dynamics within the reconnection diffusion region. The DES consists of eight half-top-hat energy analyzers. Each analyzer has a 6 deg. x 11.25 deg. Full-sky coverage is achieved by electrostatically stepping the FOV of each of the eight sensors through four discrete deflection look directions. Data compression and burst memory management will provide approximately 30 minutes of high time resolution data during each orbit of the four MMS spacecraft. Each spacecraft will intelligently downlink the data sequences that contain the greatest amount of temporal structure. Here we present the results of a simulation of the DES analyzer measurements, data compression and decompression, as well as ground-based analysis using as a seed re-processed Cluster/PEACE electron measurements. The Cluster/PEACE electron measurements have been reprocessed through virtual DES analyzers with their proper geometrical, energy, and timing scale factors and re-mapped via interpolation to the DES angular and energy phase-space sampling measurements. The results of the simulated DES measurements are analyzed and the full moments of the simulated VDFs are compared with those obtained from the Cluster/PEACE spectrometer using a standard quadrature moment, a newly implemented spectral spherical harmonic method, and a singular value decomposition method. Our preliminary moment calculations show a remarkable agreement within the uncertainties of the measurements, with the results obtained by the Cluster/PEACE electron spectrometers. The data analyzed was selected because it represented a potential reconnection event as currently published.

Dynamics of merging: post-merger mixing and relaxation of an Illustris galaxy

NASA Astrophysics Data System (ADS)

Young, Anthony M.; Williams, Liliya L. R.; Hjorth, Jens

2018-02-01

During the merger of two galaxies, the resulting system undergoes violent relaxation and seeks stable equilibrium. However, the details of this evolution are not fully understood. Using Illustris simulation, we probe two physically related processes, mixing and relaxation. Though the two are driven by the same dynamics—global time-varying potential for the energy, and torques caused by asymmetries for angular momentum—we measure them differently. We define mixing as the redistribution of energy and angular momentum between particles of the two merging galaxies. We assess the degree of mixing as the difference between the shapes of their energy distributions, N(E)s, and their angular momentum distributions, N(L2)s. We find that the difference is decreasing with time, indicating mixing. To measure relaxation, we compare N(E) of the newly merged system to N(E) of a theoretical prediction for relaxed collisionless systems, DARKexp, and witness the system becoming more relaxed, in the sense that N(E) approaches DARKexp N(E). Because the dynamics driving mixing and relaxation are the same, the timescale is similar for both. We measure two sequential timescales: a rapid, 1 Gyr phase after the initial merger, during which the difference in N(E) of the two merging halos decreases by ~ 80%, followed by a slow phase, when the difference decreases by ~ 50% over ~ 8.5 Gyrs. This is a direct measurement of the relaxation timescale. Our work also draws attention to the fact that when a galaxy has reached Jeans equilibrium it may not yet have reached a fully relaxed state given by DARKexp, in that it retains information about its past history. This manifests itself most strongly in stars being centrally concentrated. We argue that it is particularly difficult for stars, and other tightly bound particles, to mix because they have less time to be influenced by the fluctuating potential, even across multiple merger events.

Malocclusion Class II division 1 skeletal and dental relationships measured by cone-beam computed tomography.

PubMed

Xu, Yiling; Oh, Heesoo; Lagravère, Manuel O

2017-09-01

The purpose of this study was to locate traditionally-used landmarks in two-dimensional (2D) images and newly-suggested ones in three-dimensional (3D) images (cone-beam computer tomographies [CBCTs]) and determine possible relationships between them to categorize patients with Class II-1 malocclusion. CBCTs from 30 patients diagnosed with Class II-1 malocclusion were obtained from the University of Alberta Graduate Orthodontic Program database. The reconstructed images were downloaded and visualized using the software platform AVIZO ® . Forty-two landmarks were chosen and the coordinates were then obtained and analyzed using linear and angular measurements. Ten images were analyzed three times to determine the reliability and measurement error of each landmark using Intra-Class Correlation coefficient (ICC). Descriptive statistics were done using the SPSS statistical package to determine any relationships. ICC values were excellent for all landmarks in all axes, with the highest measurement error of 2mm in the y-axis for the Gonion Left landmark. Linear and angular measurements were calculated using the coordinates of each landmark. Descriptive statistics showed that the linear and angular measurements used in the 2D images did not correlate well with the 3D images. The lowest standard deviation obtained was 0.6709 for S-GoR/N-Me, with a mean of 0.8016. The highest standard deviation was 20.20704 for ANS-InfraL, with a mean of 41.006. The traditional landmarks used for 2D malocclusion analysis show good reliability when transferred to 3D images. However, they did not reveal specific skeletal or dental patterns when trying to analyze 3D images for malocclusion. Thus, another technique should be considered when classifying 3D CBCT images for Class II-1malocclusion. Copyright © 2017 CEO. Published by Elsevier Masson SAS. All rights reserved.

Space Mirror Alignment System

NASA Technical Reports Server (NTRS)

Jau, Bruno M.; McKinney, Colin; Smythe, Robert F.; Palmer, Dean L.

2011-01-01

An optical alignment mirror mechanism (AMM) has been developed with angular positioning accuracy of +/-0.2 arcsec. This requires the mirror s linear positioning actuators to have positioning resolutions of +/-112 nm to enable the mirror to meet the angular tip/tilt accuracy requirement. Demonstrated capabilities are 0.1 arc-sec angular mirror positioning accuracy, which translates into linear positioning resolutions at the actuator of 50 nm. The mechanism consists of a structure with sets of cross-directional flexures that enable the mirror s tip and tilt motion, a mirror with its kinematic mount, and two linear actuators. An actuator comprises a brushless DC motor, a linear ball screw, and a piezoelectric brake that holds the mirror s position while the unit is unpowered. An interferometric linear position sensor senses the actuator s position. The AMMs were developed for an Astrometric Beam Combiner (ABC) optical bench, which is part of an interferometer development. Custom electronics were also developed to accommodate the presence of multiple AMMs within the ABC and provide a compact, all-in-one solution to power and control the AMMs.

Slumped glass optics with interfacing ribs for high angular resolution x-ray astronomy: a progress report

NASA Astrophysics Data System (ADS)

Civitani, M.; Basso, S.; Brizzolari, C.; Ghigo, M.; Pareschi, G.; Salmaso, B.; Spiga, D.; Vecchi, G.; Breunig, E.; Burwitz, V.; Hartner, G. D.; Menz, B.

2015-09-01

The Slumped Glass Optics technology, developed at INAF/OAB since a few years, is becoming a competitive solution for the realization of the future X-ray telescopes with a very large collecting area, as e.g. the proposed Athena, with more than 2 m2 effective area at 1 keV and with a high angular resolution (5'' HEW). The developed technique is based on modular elements, named X-ray Optical Units (XOUs), made of several layers of thin foils of glass, previously formed by direct hot slumping in cylindrical configuration, and then stacked in a Wolter-I configuration, through interfacing ribs. The achievable global angular resolution of the optics relies on the surface shape accuracy of the slumped foils, on the smoothness of the mirror surfaces and on the correct integration and co-alignment of the mirror segments achieved with a dedicated Integration Machine (IMA). In this paper we provide an update of the project development, reporting on the last results achieved. In particular, we will present the results obtained with full illumination X-ray tests for the last developed prototypes.

Gas Accretion and Angular Momentum

NASA Astrophysics Data System (ADS)

Stewart, Kyle R.

In this chapter, we review the role of gas accretion to the acquisition of angular momentum, both in galaxies and in their gaseous halos. We begin by discussing angular momentum in dark matter halos, with a brief review of tidal torque theory and the importance of mergers, followed by a discussion of the canonical picture of galaxy formation within this framework, where halo gas is presumed to shock-eat to the virial temperature of the halo, following the same spin distribution as the dark matter halo before cooling to the center of the halo to form a galaxy there. In the context of recent observational evidence demonstrating the presence of high angular momentum gas in galaxy halos, we review recent cosmological hydrodynamic simulations that have begun to emphasize the role of "cold flow" accretion—anisotropic gas accretion along cosmic filaments that does not shock-heat before sinking to the central galaxy. We discuss the implications of these simulations, reviewing a number of recent developments in the literature, and suggest a revision to the canonical model as it relates to the expected angular momentum content of gaseous halos around galaxies.

A Novel Permanent Magnetic Angular Acceleration Sensor

PubMed Central

Zhao, Hao; Feng, Hao

2015-01-01

Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s−2). Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability. PMID:26151217

Spacecraft angular velocity estimation algorithm for star tracker based on optical flow techniques

NASA Astrophysics Data System (ADS)

Tang, Yujie; Li, Jian; Wang, Gangyi

2018-02-01

An integrated navigation system often uses the traditional gyro and star tracker for high precision navigation with the shortcomings of large volume, heavy weight and high-cost. With the development of autonomous navigation for deep space and small spacecraft, star tracker has been gradually used for attitude calculation and angular velocity measurement directly. At the same time, with the dynamic imaging requirements of remote sensing satellites and other imaging satellites, how to measure the angular velocity in the dynamic situation to improve the accuracy of the star tracker is the hotspot of future research. We propose the approach to measure angular rate with a nongyro and improve the dynamic performance of the star tracker. First, the star extraction algorithm based on morphology is used to extract the star region, and the stars in the two images are matched according to the method of angular distance voting. The calculation of the displacement of the star image is measured by the improved optical flow method. Finally, the triaxial angular velocity of the star tracker is calculated by the star vector using the least squares method. The method has the advantages of fast matching speed, strong antinoise ability, and good dynamic performance. The triaxial angular velocity of star tracker can be obtained accurately with these methods. So, the star tracker can achieve better tracking performance and dynamic attitude positioning accuracy to lay a good foundation for the wide application of various satellites and complex space missions.

A Methodologic Approach for Normalizing Angular Work and Velocity During Isotonic and Isokinetic Eccentric Training

PubMed Central

Guilhem, Gaël; Cornu, Christophe; Guével, Arnaud

2012-01-01

Context: Resistance exercise training commonly is performed against a constant external load (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied. Objective: To examine whether the standardization protocol could be adjusted and applied to an eccentric training program. Design: Controlled laboratory study. Setting: Controlled research laboratory. Patients or Other Participants: Twenty-one sport science male students (age = 20.6 ± 1.5 years, height = 178.0 ± 4.0 cm, mass = 74.5 ± 9.1 kg). Intervention(s): Participants performed 9 weeks of isotonic (n = 11) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity. Main Outcome Measure(s): Angular work and angular velocity. Results: The isotonic and isokinetic groups performed the same total amount of work (−185.2 ± 6.5 kJ and −184.4 ± 8.6 kJ, respectively) at the same angular velocity (21 ± 1°/s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training. Conclusions: The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury. PMID:22488276

Equilibrium properties of the Skylab CMG rotation law

NASA Technical Reports Server (NTRS)

Elrod, B. D.; Anderson, G. M.

1972-01-01

The equilibrium properties of the control moment gyroscopes of the Skylab are discussed. A rotation law is developed to produce gimbal rates which distribute the angular momentum contributions among the control moment gyroscopes to avoid gimbal stop encounters. The implications for gimbal angle management under various angular momentum situations are described. Conditions were obtained for the existence of equilibria and corresponding stability properties.

Mechanical aspects of a multidirectional, angular stable osteosynthesis system and comparison with four conventional systems.

PubMed

Gbara, Ali; Heiland, Max; Schmelzle, Rainer; Blake, Felix

2008-04-01

Following open reduction, internal fixation of fractures of the mandible is predominantly achieved using plates and screws. Today, a multitude of osteosynthesis systems are available on the market. One therapy modality, primarily developed for orthopaedic surgery, is using angular stable osteosynthesis plate systems. The dominating principle of these is the bond between screw and plate following insertion. This principle of an "internal fixateur" results in a more stable fixation of the fragments associated with less compression of the bone surfaces. A new multidirectional osteosynthesis system (TiFix=Smartlock, Hamburg - Germany) was modified to fit the maxillofacial region and compared with four other well established osteosynthesis systems developed by Mondial, Medicon, Synthes, Leibinger-Stryker, one of these (Unilock by Synthes) being also angular stable. The resistance to deformation in varying directions was investigated following fixation in four different materials. The TiFix system proved more resistant to deformation even when mounted with fewer screws than the non-angular stable systems. This system results in greater stability even when fewer screws are used. For the clinician this means smaller access incisions, less soft tissue trauma, better aesthetic results, decreased duration of operation and a reduction of costs.

Angular filter refractometry analysis using simulated annealing [An improved method for characterizing plasma density profiles using angular filter refractometry

DOE PAGES

Angland, P.; Haberberger, D.; Ivancic, S. T.; ...

2017-10-30

Here, a new method of analysis for angular filter refractometry images was developed to characterize laser-produced, long-scale-length plasmas using an annealing algorithm to iterative converge upon a solution. Angular filter refractometry (AFR) is a novel technique used to characterize the density pro files of laser-produced, long-scale-length plasmas. A synthetic AFR image is constructed by a user-defined density profile described by eight parameters, and the algorithm systematically alters the parameters until the comparison is optimized. The optimization and statistical uncertainty calculation is based on a minimization of themore » $$\\chi$$2 test statistic. The algorithm was successfully applied to experimental data of plasma expanding from a flat, laser-irradiated target, resulting in average uncertainty in the density profile of 5-10% in the region of interest.« less

Angular filter refractometry analysis using simulated annealing [An improved method for characterizing plasma density profiles using angular filter refractometry

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

Angland, P.; Haberberger, D.; Ivancic, S. T.

Here, a new method of analysis for angular filter refractometry images was developed to characterize laser-produced, long-scale-length plasmas using an annealing algorithm to iterative converge upon a solution. Angular filter refractometry (AFR) is a novel technique used to characterize the density pro files of laser-produced, long-scale-length plasmas. A synthetic AFR image is constructed by a user-defined density profile described by eight parameters, and the algorithm systematically alters the parameters until the comparison is optimized. The optimization and statistical uncertainty calculation is based on a minimization of themore » $$\\chi$$2 test statistic. The algorithm was successfully applied to experimental data of plasma expanding from a flat, laser-irradiated target, resulting in average uncertainty in the density profile of 5-10% in the region of interest.« less

MEMS high-speed angular-position sensing system with rf wireless transmission

NASA Astrophysics Data System (ADS)

Sun, Winston; Li, Wen J.

2001-08-01

A novel surface-micromachined non-contact high-speed angular-position sensor with total surface area under 4mm2 was developed using the Multi-User MEMS Processes (MUMPs) and integrated with a commercial RF transmitter at 433MHz carrier frequency for wireless signal detection. Currently, a 2.3 MHz internal clock of our data acquisition system and a sensor design with a 13mg seismic mass is sufficient to provide visual observation of a clear sinusoidal response wirelessly generated by the piezoresistive angular-position sensing system within speed range of 180 rpm to around 1000 rpm. Experimental results showed that the oscillation frequency and amplitude are related to the input angular frequency of the rotation disk and the tilt angle of the rotation axis, respectively. These important results could provide groundwork for MEMS researchers to estimate how gravity influences structural properties of MEMS devices under different circumstances.

New dynamic variables for rotating spacecraft

NASA Technical Reports Server (NTRS)

Markley, F. Landis

1993-01-01

This paper introduces two new seven-parameter representations for spacecraft attitude dynamics modeling. The seven parameters are the three components of the total system angular momentum in the spacecraft body frame; the three components of the angular momentum in the inertial reference frame; and an angle variable. These obey a single constraint as do parameterizations that include a quaternion; in this case the constraint is the equality of the sum of the squares of the angular momentum components in the two frames. The two representations are nonsingular if the system angular momentum is non-zero and obeys certain orientation constraints. The new parameterizations of the attitude matrix, the equations of motion, and the relation of the solution of these equations to Euler angles for torque-free motion are developed and analyzed. The superiority of the new parameterizations for numerical integration is shown in a specific example.

Collapse and Nonlinear Instability of AdS Space with Angular Momentum

NASA Astrophysics Data System (ADS)

Choptuik, Matthew W.; Dias, Óscar J. C.; Santos, Jorge E.; Way, Benson

2017-11-01

We present a numerical study of rotational dynamics in AdS5 with equal angular momenta in the presence of a complex doublet scalar field. We determine that the endpoint of gravitational collapse is a Myers-Perry black hole for high energies and a hairy black hole for low energies. We investigate the time scale for collapse at low energies E , keeping the angular momenta J ∝E in anti-de Sitter (AdS) length units. We find that the inclusion of angular momenta delays the collapse time, but retains a t ˜1 /E scaling. We perturb and evolve rotating boson stars, and find that boson stars near AdS space appear stable, but those sufficiently far from AdS space are unstable. We find that the dynamics of the boson star instability depend on the perturbation, resulting either in collapse to a Myers-Perry black hole, or development towards a stable oscillating solution.

Tunable orbital angular momentum in high-harmonic generation

PubMed Central

Gauthier, D.; Ribič, P. Rebernik; Adhikary, G.; Camper, A.; Chappuis, C.; Cucini, R.; DiMauro, L. F.; Dovillaire, G.; Frassetto, F.; Géneaux, R.; Miotti, P.; Poletto, L.; Ressel, B.; Spezzani, C.; Stupar, M.; Ruchon, T.; De Ninno, G.

2017-01-01

Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light–matter interactions, and the disentanglement and independent control of the intrinsic and extrinsic components of the photon's angular momentum at short-wavelengths. The methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms. PMID:28378741

Optimization and Prediction of Angular Distortion and Weldment Characteristics of TIG Square Butt Joints

NASA Astrophysics Data System (ADS)

Narang, H. K.; Mahapatra, M. M.; Jha, P. K.; Biswas, P.

2014-05-01

Autogenous arc welds with minimum upper weld bead depression and lower weld bead bulging are desired as such welds do not require a second welding pass for filling up the upper bead depressions (UBDs) and characterized with minimum angular distortion. The present paper describes optimization and prediction of angular distortion and weldment characteristics such as upper weld bead depression and lower weld bead bulging of TIG-welded structural steel square butt joints. Full factorial design of experiment was utilized for selecting the combinations of welding process parameter to produce the square butts. A mathematical model was developed to establish the relationship between TIG welding process parameters and responses such as upper bead width, lower bead width, UBD, lower bead height (bulging), weld cross-sectional area, and angular distortions. The optimal welding condition to minimize UBD and lower bead bulging of the TIG butt joints was identified.

A novel upwind stabilized discontinuous finite element angular framework for deterministic dose calculations in magnetic fields.

PubMed

Yang, R; Zelyak, O; Fallone, B G; St-Aubin, J

2018-01-30

Angular discretization impacts nearly every aspect of a deterministic solution to the linear Boltzmann transport equation, especially in the presence of magnetic fields, as modeled by a streaming operator in angle. In this work a novel stabilization treatment of the magnetic field term is developed for an angular finite element discretization on the unit sphere, specifically involving piecewise partitioning of path integrals along curved element edges into uninterrupted segments of incoming and outgoing flux, with outgoing components updated iteratively. Correct order-of-accuracy for this angular framework is verified using the method of manufactured solutions for linear, quadratic, and cubic basis functions in angle. Higher order basis functions were found to reduce the error especially in strong magnetic fields and low density media. We combine an angular finite element mesh respecting octant boundaries on the unit sphere to spatial Cartesian voxel elements to guarantee an unambiguous transport sweep ordering in space. Accuracy for a dosimetrically challenging scenario involving bone and air in the presence of a 1.5 T parallel magnetic field is validated against the Monte Carlo package GEANT4. Accuracy and relative computational efficiency were investigated for various angular discretization parameters. 32 angular elements with quadratic basis functions yielded a reasonable compromise, with gamma passing rates of 99.96% (96.22%) for a 2%/2 mm (1%/1 mm) criterion. A rotational transformation of the spatial calculation geometry is performed to orient an arbitrary magnetic field vector to be along the z-axis, a requirement for a constant azimuthal angular sweep ordering. Working on the unit sphere, we apply the same rotational transformation to the angular domain to align its octants with the rotated Cartesian mesh. Simulating an oblique 1.5 T magnetic field against GEANT4 yielded gamma passing rates of 99.42% (95.45%) for a 2%/2 mm (1%/1 mm) criterion.

A novel upwind stabilized discontinuous finite element angular framework for deterministic dose calculations in magnetic fields

NASA Astrophysics Data System (ADS)

Yang, R.; Zelyak, O.; Fallone, B. G.; St-Aubin, J.

2018-02-01

Angular discretization impacts nearly every aspect of a deterministic solution to the linear Boltzmann transport equation, especially in the presence of magnetic fields, as modeled by a streaming operator in angle. In this work a novel stabilization treatment of the magnetic field term is developed for an angular finite element discretization on the unit sphere, specifically involving piecewise partitioning of path integrals along curved element edges into uninterrupted segments of incoming and outgoing flux, with outgoing components updated iteratively. Correct order-of-accuracy for this angular framework is verified using the method of manufactured solutions for linear, quadratic, and cubic basis functions in angle. Higher order basis functions were found to reduce the error especially in strong magnetic fields and low density media. We combine an angular finite element mesh respecting octant boundaries on the unit sphere to spatial Cartesian voxel elements to guarantee an unambiguous transport sweep ordering in space. Accuracy for a dosimetrically challenging scenario involving bone and air in the presence of a 1.5 T parallel magnetic field is validated against the Monte Carlo package GEANT4. Accuracy and relative computational efficiency were investigated for various angular discretization parameters. 32 angular elements with quadratic basis functions yielded a reasonable compromise, with gamma passing rates of 99.96% (96.22%) for a 2%/2 mm (1%/1 mm) criterion. A rotational transformation of the spatial calculation geometry is performed to orient an arbitrary magnetic field vector to be along the z-axis, a requirement for a constant azimuthal angular sweep ordering. Working on the unit sphere, we apply the same rotational transformation to the angular domain to align its octants with the rotated Cartesian mesh. Simulating an oblique 1.5 T magnetic field against GEANT4 yielded gamma passing rates of 99.42% (95.45%) for a 2%/2 mm (1%/1 mm) criterion.

X-ray optics for the LAMAR facility, an overview. [Large Area Modular Array of Reflectors

NASA Technical Reports Server (NTRS)

Gorenstein, P.

1979-01-01

The paper surveys the Large Area Modular Array of Reflectors (LAMAR), the concept of which is based on meeting two major requirements in X-ray astronomy, large collecting area and moderately good or better angular resolution for avoiding source confusion and imaging source fields. It is shown that the LAMAR provides the same sensitivity and signal to noise in imaging as a single large telescope having the same area and angular resolution but is a great deal less costly to develop, construct, and integrate into a space mission. Attention is also given to the LAMAR modular nature which will allow for an evolutionary development from a modest size array on Spacelab to a Shuttle launched free flyer. Finally, consideration is given to manufacturing methods which show promise of making LAMAR meet the criteria of good angular resolution, relatively low cost, and capability for fast volume production.

High resolution tip-tilt positioning system for a next generation MLL-based x-ray microscope

DOE PAGES

Xu, Weihe; Schlossberger, Noah; Xu, Wei; ...

2017-11-15

Multilayer Laue lenses (MLLs) are x-ray focusing optics with the potential to focus hard x-rays down to a single nanometer level. In order to achieve point focus, an MLL microscope needs to have the capability to perform tip-tilt motion of MLL optics and to hold the angular position for an extended period of time. Here, we present a 2D tip-tilt system that can achieve an angular resolution of over 100 microdegree with a working range of 4°, by utilizing a combination of laser interferometer and mini retroreflector. The linear dimensions of the developed system are about 30 mm in allmore » directions, and the thermal dissipation of the system during operation is negligible. Compact design and high angular resolution make the developed system suitable for MLL optics alignment in the next generation of MLL-based x-ray microscopes.« less

High resolution tip-tilt positioning system for a next generation MLL-based x-ray microscope

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

Xu, Weihe; Schlossberger, Noah; Xu, Wei

Multilayer Laue lenses (MLLs) are x-ray focusing optics with the potential to focus hard x-rays down to a single nanometer level. In order to achieve point focus, an MLL microscope needs to have the capability to perform tip-tilt motion of MLL optics and to hold the angular position for an extended period of time. Here, we present a 2D tip-tilt system that can achieve an angular resolution of over 100 microdegree with a working range of 4°, by utilizing a combination of laser interferometer and mini retroreflector. The linear dimensions of the developed system are about 30 mm in allmore » directions, and the thermal dissipation of the system during operation is negligible. Compact design and high angular resolution make the developed system suitable for MLL optics alignment in the next generation of MLL-based x-ray microscopes.« less

Encoding of head acceleration in vestibular neurons. I. Spatiotemporal response properties to linear acceleration

NASA Technical Reports Server (NTRS)

Bush, G. A.; Perachio, A. A.; Angelaki, D. E.

1993-01-01

1. Extracellular recordings were made in and around the medial vestibular nuclei in decerebrated rats. Neurons were functionally identified according to their semicircular canal input on the basis of their responses to angular head rotations around the yaw, pitch, and roll head axes. Those cells responding to angular acceleration were classified as either horizontal semicircular canal-related (HC) or vertical semicircular canal-related (VC) neurons. The HC neurons were further characterized as either type I or type II, depending on the direction of rotation producing excitation. Cells that lacked a response to angular head acceleration, but exhibited sensitivity to a change in head position, were classified as purely otolith organ-related (OTO) neurons. All vestibular neurons were then tested for their response to sinusoidal linear translation in the horizontal head plane. 2. Convergence of macular and canal inputs onto central vestibular nuclei neurons occurred in 73% of the type I HC, 79% of the type II HC, and 86% of the VC neurons. Out of the 223 neurons identified as receiving macular input, 94 neurons were further studied, and their spatiotemporal response properties to sinusoidal stimulation with pure linear acceleration were quantified. Data were obtained from 33 type I HC, 22 type II HC, 22 VC, and 17 OTO neurons. 3. For each neuron the angle of the translational stimulus vector was varied by 15, 30, or 45 degrees increments in the horizontal head plane. In all tested neurons, a direction of maximum sensitivity was identified. An interesting difference among neurons was their response to translation along the direction perpendicular to that that produced the maximum response ("null" direction). For the majority of neurons tested, it was possible to evoke a nonzero response during stimulation along the null direction always had response phases that varied as a function of stimulus direction. 4. These spatiotemporal response properties were quantified in two independent ways. First, the data were evaluated on the basis of the traditional one-dimensional principle governed by the "cosine gain rule" and constant response phase at different stimulus orientations. Second, the response gain and phase values that were empirically determined for each orientation of the applied linear stimulus vector were fitted on the basis of a newly developed formalism that treats neuronal responses as exhibiting two-dimensional spatial sensitivity. Thus two response vectors were determined for each neuron on the basis of its response gain and phase at different stimulus directions in the horizontal head plane.(ABSTRACT TRUNCATED AT 400 WORDS).

Energy transport in cooling device by magnetic fluid

NASA Astrophysics Data System (ADS)

Yamaguchi, Hiroshi; Iwamoto, Yuhiro

2017-06-01

Temperature sensitive magnetic fluid has a great potential with high performance heat transport ability as well as long distance energy (heat) transporting. In the present study experimental set-up was newly designed and constructed in order to measure basic heat transport characteristics under various magnetic field conditions. Angular dependence for the device (heat transfer section) was also taken into consideration for a sake of practical applications. The energy transfer characteristic (heat transport capability) in the magnetically-driven heat transport (cooling) device using the binary TSMF was fully investigated with the set-up. The obtained results indicate that boiling of the organic mixture (before the magnetic fluid itself reaching boiling point) effectively enhances the heat transfer as well as boosting the flow to circulate in the closed loop by itself. A long-distance heat transport of 5 m is experimentally confirmed, transferring the thermal energy of 35.8 W, even when the device (circulation loop) is horizontally placed. The highlighted results reveal that the proposed cooling device is innovative in a sense of transporting substantial amount of thermal energy (heat) as well as a long distance heat transport. The development of the magnetically-driven heat transport device has a great potential to be replaced for the conventional heat pipe in application of thermal engineering.

Data fusion in X-ray computed tomography using a superiorization approach.

PubMed

Schrapp, Michael J; Herman, Gabor T

2014-05-01

X-ray computed tomography (CT) is an important and widespread inspection technique in industrial non-destructive testing. However, large-sized and heavily absorbing objects cause artifacts due to either the lack of penetration of the specimen in specific directions or by having data from only a limited angular range of views. In such cases, valuable information about the specimen is not revealed by the CT measurements alone. Further imaging modalities, such as optical scanning and ultrasonic testing, are able to provide data (such as an edge map) that are complementary to the CT acquisition. In this paper, a superiorization approach (a newly developed method for constrained optimization) is used to incorporate the complementary data into the CT reconstruction; this allows precise localization of edges that are not resolvable from the CT data by itself. Superiorization, as presented in this paper, exploits the fact that the simultaneous algebraic reconstruction technique (SART), often used for CT reconstruction, is resilient to perturbations; i.e., it can be modified to produce an output that is as consistent with the CT measurements as the output of unmodified SART, but is more consistent with the complementary data. The application of this superiorized SART method to measured data of a turbine blade demonstrates a clear improvement in the quality of the reconstructed image.

High Fill-out, Extreme Mass Ratio Overcontact Binary Systems. X. The Newly Discovered Binary XY Leonis Minoris

NASA Astrophysics Data System (ADS)

Qian, S.-B.; Liu, L.; Zhu, L.-Y.; He, J.-J.; Yang, Y.-G.; Bernasconi, L.

2011-05-01

The newly discovered short-period close binary star, XY LMi, has been monitored photometrically since 2006. Its light curves are typical EW-type light curves and show complete eclipses with durations of about 80 minutes. Photometric solutions were determined through an analysis of the complete B, V, R, and I light curves using the 2003 version of the Wilson-Devinney code. XY LMi is a high fill-out, extreme mass ratio overcontact binary system with a mass ratio of q = 0.148 and a fill-out factor of f = 74.1%, suggesting that it is in the late evolutionary stage of late-type tidal-locked binary stars. As observed in other overcontact binary stars, evidence for the presence of two dark spots on both components is given. Based on our 19 epochs of eclipse times, we found that the orbital period of the overcontact binary is decreasing continuously at a rate of dP/dt = -1.67 × 10-7 days yr-1, which may be caused by mass transfer from the primary to the secondary and/or angular momentum loss via magnetic stellar wind. The decrease of the orbital period may result in the increase of the fill-out, and finally, it will evolve into a single rapid-rotation star when the fluid surface reaches the outer critical Roche lobe.

Angular circulation speed of tablets in a vibratory tablet coating pan.

PubMed

Kumar, Rahul; Wassgren, Carl

2013-03-01

In this work, a single tablet model and a discrete element method (DEM) computer simulation are developed to obtain the angular circulation speed of tablets in a vibratory tablet coating pan for range of vibration frequencies and amplitudes. The models identify three important dimensionless parameters that influence the speed of the tablets: the dimensionless amplitude ratio (a/R), the Froude number (aω2/g), and the tablet-wall friction coefficient, where a is the peak vibration amplitude at the drum center, ω is the vibration angular frequency, R is the drum radius, and g is the acceleration due to gravity. The models predict that the angular circulation speed of tablets increases with an increase in each of these parameters. The rate of increase in the angular circulation speed is observed to decrease for larger values of a/R. The angular circulation speed reaches an asymptote beyond a tablet-wall friction coefficient value of about 0.4. Furthermore, it is found that the Froude number should be greater than one for the tablets to start circulating. The angular circulation speed increases as Froude number increases but then does not change significantly at larger values of the Froude number. Period doubling, where the motion of the bed is repeated every two cycles, occurs at a Froude number larger than five. The single tablet model, although much simpler than the DEM model, is able to predict the maximum circulation speed (the limiting case for a large value of tablet-wall friction coefficient) as well as the transition to period doubling.

Field Performance of a Newly Developed Upflow Filtration Device

EPA Science Inventory

The objective of this research is to examine the removal capacities of a newly developed Upflow filtration device for treatment of stormwater. The device was developed by engineers at the University of Alabama through a Small Business Innovative Research (SBIR) grant from the U....

Correlations between Angular Velocities in Selected Joints and Velocity of Table Tennis Racket during Topspin Forehand and Backhand.

PubMed

Bańkosz, Ziemowit; Winiarski, Sławomir

2018-06-01

The aim of this study was to determine the correlations between angular velocities in individual joints and racket velocity for different topspin forehand and backhand strokes in table tennis. Ten elite female table tennis players participated, presenting different kinds of topspin forehands and backhands - after a no-spin ball (FH1, BH1), after a backspin ball (FH2, BH2) and "heavy" topspin (FH3, BH3). Range of motion was measured with the BTS Smart-E (BTS Bioengineering, Milan, Italy) motion analysis system with a specially developed marker placement protocol for the upper body parts and an acoustic sensor attached to the racket to identify ball-racket contact. In forehand strokes angular velocities of internal arm rotation and adduction in shoulder joint correlated with racket velocity. Racket velocity was correlated with angular velocities (hip extension on the playing side; hip flexion on the opposite side; ankle flexion) in the case of a topspin forehand performed with maximal force -"heavy" topspin (FH3). In backhand strokes the velocities of arm abduction and shoulder girdle rotation towards the playing side correlated with racket velocity. The angular velocity of internal arm rotation and adduction in shoulder joint may be important components of a coordinated stroke, whilst angular velocity can substantially affect the racket speed when one is changing the type of stroke.

Functional phases and angular momentum characteristics of Tkatchev and Kovacs.

PubMed

Irwin, Gareth; Exell, Timothy A; Manning, Michelle L; Kerwin, David G

2017-03-01

Understanding the technical requirements and underlying biomechanics of complex release and re-grasp skills on high bar allows coaches and scientists to develop safe and effective training programmes. The aim of this study was to examine the differences in the functional phases between the Tkatchev and Kovacs skills and to explain how the angular momentum demands are addressed. Images of 18 gymnasts performing 10 Tkatchevs and 8 Kovacs at the Olympic Games were recorded (50 Hz), digitised and reconstructed (3D Direct Linear Transformation). Orientation of the functional phase action, defined by the rapid flexion to extension of the shoulders and extension to flexion of the hips as the performer passed through the lower vertical, along with shoulder and hip angular kinematics, angular momentum and key release parameters (body angle, mass centre velocity and angular momentum about the mass centre and bar) were compared between skills. Expected differences in the release parameters of angle, angular momentum and velocity were observed and the specific mechanical requirement of each skill were highlighted. Whilst there were no differences in joint kinematics, hip and shoulder functional phase were significantly earlier in the circle for the Tkatchev. These findings highlight the importance of the orientation of the functional phase in the preceding giant swing and provide coaches with further understanding of the critical timing in this key phase.

Determination of optimum viewing angles for the angular normalization of land surface temperature over vegetated surface.

PubMed

Ren, Huazhong; Yan, Guangjian; Liu, Rongyuan; Li, Zhao-Liang; Qin, Qiming; Nerry, Françoise; Liu, Qiang

2015-03-27

Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST) retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF) is first extended to the thermal infrared (TIR) domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir) from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors.

Determination of Optimum Viewing Angles for the Angular Normalization of Land Surface Temperature over Vegetated Surface

PubMed Central

Ren, Huazhong; Yan, Guangjian; Liu, Rongyuan; Li, Zhao-Liang; Qin, Qiming; Nerry, Françoise; Liu, Qiang

2015-01-01

Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST) retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF) is first extended to the thermal infrared (TIR) domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir) from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors. PMID:25825975

Raychaudhuri equation in the self-consistent Einstein-Cartan theory with spin-density

NASA Technical Reports Server (NTRS)

Fennelly, A. J.; Krisch, Jean P.; Ray, John R.; Smalley, Larry L.

1988-01-01

The physical implications of the Raychaudhuri equation for a spinning fluid in a Riemann-Cartan spacetime is developed and discussed using the self-consistent Lagrangian based formulation for the Einstein-Cartan theory. It was found that the spin-squared terms contribute to expansion (inflation) at early times and may lead to a bounce in the final collapse. The relationship between the fluid's vorticity and spin angular velocity is clarified and the effect of the interaction terms between the spin angular velocity and the spin in the Raychaudhuri equation investigated. These results should prove useful for studies of systems with an intrinsic spin angular momentum in extreme astrophysical or cosmological problems.

Improvement of contact grating device for efficient terahertz wave generation using bi-angular filter

NASA Astrophysics Data System (ADS)

Nagashima, Keisuke; Tsubouchi, Masaaki; Ochi, Yoshihiro; Maruyama, Momoko

2018-03-01

We have proposed an improved contact grating device for generating terahertz waves efficiently and have succeeded in developing the device with a very high diffraction efficiency and a wide spectral width. This device has a bi-angular filter and a Fabry-Perot-type structure, which are composed of dielectric multilayers. The bi-angular filter is designed to reflect the 0th-order wave and transmit the-1st-order diffraction wave. Numerical calculations indicate that the new device has a maximum diffraction efficiency over 99% and a spectral width of approximately 20 nm. We measured a high efficiency of 90% over a broad spectral range using a fabricated device.

Learning by strategies and learning by drill--evidence from an fMRI study.

PubMed

Delazer, M; Ischebeck, A; Domahs, F; Zamarian, L; Koppelstaetter, F; Siedentopf, C M; Kaufmann, L; Benke, T; Felber, S

2005-04-15

The present fMRI study investigates, first, whether learning new arithmetic operations is reflected by changing cerebral activation patterns, and second, whether different learning methods lead to differential modifications of brain activation. In a controlled design, subjects were trained over a week on two new complex arithmetic operations, one operation trained by the application of back-up strategies, i.e., a sequence of arithmetic operations, the other by drill, i.e., by learning the association between the operands and the result. In the following fMRI session, new untrained items, items trained by strategy and items trained by drill, were assessed using an event-related design. Untrained items as compared to trained showed large bilateral parietal activations, with the focus of activation along the right intraparietal sulcus. Further foci of activation were found in both inferior frontal gyri. The reverse contrast, trained vs. untrained, showed a more focused activation pattern with activation in both angular gyri. As suggested by the specific activation patterns, newly acquired expertise was implemented in previously existing networks of arithmetic processing and memory. Comparisons between drill and strategy conditions suggest that successful retrieval was associated with different brain activation patterns reflecting the underlying learning methods. While the drill condition more strongly activated medial parietal regions extending to the left angular gyrus, the strategy condition was associated to the activation of the precuneus which may be accounted for by visual imagery in memory retrieval.

The Three-dimensional Structure of the Eta Carinae Homunculus

NASA Technical Reports Server (NTRS)

Steffen, W.; Teodoro, M.; Madura, T.I.; Groh, J.H.; Gull, T.R.; Mehner, A.; Corcoran, M.F.; Damineli, A.; Hamaguchi, K.

2014-01-01

We investigate, using the modeling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae as mapped by new ESO VLT/X-Shooter observations of the H2 (lambda) = 2.12125 micrometers emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: 1) circumpolar trenches in each lobe positioned point-symmetrically from the center and 2) offplanar protrusions in the equatorial region from each lobe at longitudinal (approximately 55 degrees) and latitudinal (10 degrees to 20 degrees) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (approximately 110 degrees) is similar to the angular extent of each polar trench (approximately 130 degrees) and nearly equal to the opening angle of the wind-wind collision cavity (approximately 110 degrees). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H2 emission from the thin optical skirt seen prominently in visible imagery. We conclude that the interaction between the outflows and/or radiation from the central binary stars and their orientation in space has had, and possibly still has, a strong influence on the Homunculus. This implies that prevailing theoretical models of the Homunculus are incomplete as most assume a single star origin that produces an axisymmetric nebula.We discuss how the newly found features might be related to the Homunculus ejection, the central binary and the interacting stellar winds.

Chasing Shadows: Rotation of the Azimuthal Asymmetry in the TW Hya Disk

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

Debes, John H.; Poteet, Charles A.; Hines, Dean

2017-02-01

We have obtained new images of the protoplanetary disk orbiting TW Hya in visible, total intensity light with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope ( HST ), using the newly commissioned BAR5 occulter. These HST /STIS observations achieved an inner working angle of ∼0.″2, or 11.7 au, probing the system at angular radii coincident with recent images of the disk obtained by ALMA and in polarized intensity near-infrared light. By comparing our new STIS images to those taken with STIS in 2000 and with NICMOS in 1998, 2004, and 2005, we demonstrate that TW Hya’smore » azimuthal surface brightness asymmetry moves coherently in position angle. Between 50 au and 141 au we measure a constant angular velocity in the azimuthal brightness asymmetry of 22.°7 yr{sup −1} in a counterclockwise direction, equivalent to a period of 15.9 yr assuming circular motion. Both the (short) inferred period and lack of radial dependence of the moving shadow pattern are inconsistent with Keplerian rotation at these disk radii. We hypothesize that the asymmetry arises from the fact that the disk interior to 1 au is inclined and precessing owing to a planetary companion, thus partially shadowing the outer disk. Further monitoring of this and other shadows on protoplanetary disks potentially opens a new avenue for indirectly observing the sites of planet formation.« less

High-resolution multi-band imaging for validation and characterization of small Kepler planets

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

Everett, Mark E.; Silva, David R.; Barclay, Thomas

2015-02-01

High-resolution ground-based optical speckle and near-infrared adaptive optics images are taken to search for stars in close angular proximity to host stars of candidate planets identified by the NASA Kepler Mission. Neighboring stars are a potential source of false positive signals. These stars also blend into Kepler light curves, affecting estimated planet properties, and are important for an understanding of planets in multiple star systems. Deep images with high angular resolution help to validate candidate planets by excluding potential background eclipsing binaries as the source of the transit signals. A study of 18 Kepler Object of Interest stars hosting amore » total of 28 candidate and validated planets is presented. Validation levels are determined for 18 planets against the likelihood of a false positive from a background eclipsing binary. Most of these are validated at the 99% level or higher, including five newly validated planets in two systems: Kepler-430 and Kepler-431. The stellar properties of the candidate host stars are determined by supplementing existing literature values with new spectroscopic characterizations. Close neighbors of seven of these stars are examined using multi-wavelength photometry to determine their nature and influence on the candidate planet properties. Most of the close neighbors appear to be gravitationally bound secondaries, while a few are best explained as closely co-aligned field stars. Revised planet properties are derived for each candidate and validated planet, including cases where the close neighbors are the potential host stars.« less

Development of a Magneto-Resistive Angular Position Sensor for Space Mechanisms

NASA Technical Reports Server (NTRS)

Hahn, Robert; Schmidt, Tilo; Seifart, Klaus; Olberts, Bastian; Romera, Fernando

2016-01-01

Magnetic microsystems in the form of magneto-resistive (MR) sensors are firmly established in automobiles and industrial applications. They are used to measure travel, angle, electrical current, or magnetic fields. MR technology opens up new sensor possibilities in space applications and can be an enabling technology for optimal performance, high robustness and long lifetime at reasonable costs. In some science missions, the technology is already applied, however, the designs are proprietary and case specific, for instance in case of the angular sensors used for JPL/NASA's Mars rover Curiosity [1]. Since 2013 HTS GmbH and Sensitec GmbH have teamed up to develop and qualify a standardized yet flexible to use MR angular sensor for space mechanisms. Starting with a first assessment study and market survey performed under ESA contract, a very strong industry interest in novel, contactless position measurement means was found. Currently a detailed and comprehensive development program is being performed by HTS and Sensitec. The objective of this program is to advance the sensor design up to Engineering Qualification Model level and to perform qualification testing for a representative space application. The paper briefly reviews the basics of magneto-resistive effects and possible sensor applications and describes the key benefits of MR angular sensors with reference to currently operational industrial and space applications. The key applications and specification are presented and the preliminary baseline mechanical and electrical design will be discussed. An outlook on the upcoming development and test stages as well as the qualification program will be provided.

Assessing College Students' Perceptions of a Case Teacher's Pedagogical Content Knowledge Using a Newly Developed Instrument

ERIC Educational Resources Information Center

Jang, Syh-Jong

2011-01-01

Ongoing professional development for college teachers has been much emphasized. However, previous research on learning environments has seldom addressed college students' perceptions of teachers' PCK. This study aimed to evaluate college students' perceptions of a physics teacher's PCK development using a newly developed instrument and workshop…

Preparing School Leaders: The Professional Development Needs of Newly Appointed Principals

ERIC Educational Resources Information Center

Ng, Shun-wing; Szeto, Sing-ying Elson

2016-01-01

In Hong Kong, there is an acute need to provide newly appointed principals with opportunities for continuous professional development so that they could face the impact of reforms and globalization on school development. The Education Bureau has commissioned the tertiary institutions to provide structured professional development courses to cater…

Experimental 64Zn(d⃗,t)63Zn spectroscopic factors: Guidance for isospin-symmetry-breaking calculations

NASA Astrophysics Data System (ADS)

Leach, K. G.; Garrett, P. E.; Towner, I. S.; Ball, G. C.; Bildstein, V.; Brown, B. A.; Demand, G. A.; Faestermann, T.; Finlay, P.; Green, K. L.; Hertenberger, R.; Krücken, R.; Phillips, A. A.; Rand, E. T.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wirth, H.-F.; Wong, J.

2013-06-01

With the recent inclusion of core orbitals to the radial-overlap component of the isospin-symmetry-breaking (ISB) corrections for superallowed Fermi β decay, experimental data are needed to test the validity of the theoretical model. This work reports measurements of single-neutron pickup reaction spectroscopic factors into 63Zn, one neutron away from 62Zn, the superallowed daughter of 62Ga. The experiment was performed using a 22-MeV polarized deuteron beam, a Q3D magnetic spectrograph, and a cathode-strip focal-plane detector to analyze outgoing tritons at nine angles between 10∘ and 60∘. Angular distributions and vector analyzing powers were obtained for all 162 observed states in 63Zn, including 125 newly observed levels, up to an excitation energy of 4.8 MeV. Spectroscopic factors are extracted and compared to several shell-model predictions, and implications for the ISB calculations are discussed.

Apparently new osteodysplastic and primordial short stature with severe microdontia, opalescent teeth, and rootless molars in two siblings.

PubMed

Kantaputra, Piranit N

2002-09-01

A Thai man and his sister affected with a newly recognized syndrome of proportionate primordial short stature are reported. The patients had severe intrauterine and postnatal growth retardation, prominent nose and nasal bridge, small pinnae, large sella turcica, areas of hypo- and hyperpigmentation of skin, dry and thin scalp hair, and long and straight clavicles. Ivory epiphyses and cone-shaped epiphyses of the hands were found when they were young, but most of them disappeared as they grew up. Scaphoid and trapezium had angular appearance. The second toes were unusually long. Distal symphalangism of toes and barchymesophalangy of fingers were noted. The findings that appear to distinguish this syndrome from the previously reported syndromes are long second toes, opalescent and rootless teeth, severe microdontia, severely hypoplastic alveolar process, and unerupted tooth. The mode of inheritance is suspected to be autosomal recessive. Copyright 2002 Wiley-Liss, Inc.

Simulating Shock Triggered Star Formation with AstroBEAR2.0

NASA Astrophysics Data System (ADS)

Li, Shule; Frank, Adam; Blackman, Eric

2013-07-01

Star formation can be triggered by the compression from shocks running over stable clouds. Triggered star formation is a favored explanation for the traces of SLRI's in our solar system. Previous research has shown that when parameters such as shock speed are within a certain range, the gravitational collapse of otherwise stable, dense cloud cores is possible. However, these studies usually focus on the precursors of star formation, and the conditions for the triggering. We use AstroBEAR2.0 code to simulate the collapse and subsequent evolution of a stable Bonnor-Ebert cloud by an incoming shock. Through our simulations, we show that interesting physics happens when the newly formed star interacts with the cloud residue and the post-shock flow. We identify these interactions as controlled by the initial conditions of the triggering and study the flow pattern as well as the evolution of important physics quantities such as accretion rate and angular momentum.

Automatic Detection of Pearlite Spheroidization Grade of Steel Using Optical Metallography.

PubMed

Chen, Naichao; Chen, Yingchao; Ai, Jun; Ren, Jianxin; Zhu, Rui; Ma, Xingchi; Han, Jun; Ma, Qingqian

2016-02-01

To eliminate the effect of subjective factors during manually determining the pearlite spheroidization grade of steel by analysis of optical metallography images, a novel method combining image mining and artificial neural networks (ANN) is proposed. The four co-occurrence matrices of angular second moment, contrast, correlation, and entropy are adopted to objectively characterize the images. ANN is employed to establish a mathematical model between the four co-occurrence matrices and the corresponding spheroidization grade. Three materials used in coal-fired power plants (ASTM A315-B steel, ASTM A335-P12 steel, and ASTM A355-P11 steel) were selected as the samples to test the validity of our proposed method. The results indicate that the accuracies of the calculated spheroidization grades reach 99.05, 95.46, and 93.63%, respectively. Hence, our newly proposed method is adequate for automatically detecting the pearlite spheroidization grade of steel using optical metallography.

Ultra-compact structure in intermediate-luminosity radio quasars: building a sample of standard cosmological rulers and improving the dark energy constraints up to z 3

NASA Astrophysics Data System (ADS)

Cao, Shuo; Zheng, Xiaogang; Biesiada, Marek; Qi, Jingzhao; Chen, Yun; Zhu, Zong-Hong

2017-09-01

Context. Ultra-compact structure in radio sources (especially in quasars that can be observed up to very high redshifts), with milliarcsecond angular sizes measured by very-long-baseline interferometry (VLBI), is becoming an important astrophysical tool for probing both cosmology and the physical properties of AGN. Aims: We present a newly compiled data set of 120 milliarcsec. compact radio sources representing intermediate-luminosity quasars covering the redshift range 0.46 < z < 2.76 and check the possibility of using these sources as independent cosmological probes. These quasars observed at 2.29 GHz show negligible dependence on redshifts and intrinsic luminosity, and thus represent a fixed comoving-length of standard ruler. Methods: For a cosmological ruler with intrinsic length lm, the angular size-redshift relation can be written as θ(z) = lm/DA(z, where θ(z) is the angular size at redshift z, and DA(z) is the corresponding angular diameter distance. We use a compilation of angular size and redshift data for ultra-compact radio sources from a well-known VLBI survey, and implement a new cosmology-independent technique to calibrate the linear size of this standard ruler, which is also used to test different cosmological models with and without the flat universe assumption. Results: We determine the linear size of this standard ruler as lm = 11.03 ± 0.25 pc, which is the typical radius at which AGN jets become opaque at the observed frequency ν 2 GHz. Our measurement of this linear size is also consistent with the previous and recent radio observations at other different frequencies. In the framework of flat ΛCDM model, we find a high value of the matter density parameter, Ωm = 0.322+0.244-0.141, and a low value of the Hubble constant, H0 = 67.6+7.8-7.4 km s-1 Mpc-1, which is in excellent agreement with the cosmic microwave background (CMB) anisotropy measurements by Planck. We obtain Ωm = 0.309+0.215-0.151, w = -0.970+0.500-1.730 at 68.3% CL for the constant w of a dynamical dark-energy model, which demonstrates no significant deviation from the concordance ΛCDM model. Consistent fitting results are also obtained for other cosmological models explaining the cosmic acceleration, like Ricci dark energy (RDE) or the Dvali-Gabadadze-Porrati (DGP) brane-world scenario. While no significant change in w with redshift is detected, there is still considerable room for evolution in w and the transition redshift at which w departing from -1 is located at z 2.0. Our results demonstrate that the method extensively investigated in our work on observational radio quasar data can be used to effectively derive cosmological information. Finally, we find the combination of high-redshift quasars and low-redshift clusters may provide an important source of angular diameter distances, considering the redshift coverage of these two astrophysical probes.

REVIEWS OF TOPICAL PROBLEMS: The differential rotation of stars

NASA Astrophysics Data System (ADS)

Kitchatinov, Leonid L.

2005-05-01

Astronomical observations of recent years have substantially extended our knowledge of the rotation of stars. Helioseismology has found out that the equator-to-pole decline in the angular velocity observed on the solar surface traces down to the deep interior of the Sun. New information has been gained regarding the dependence of the rotational nonuniformities on the angular velocity and mass of the star. These achievements have prompted the development of the theory of differential rotation, which is the focal point of this review. Nonuniform rotation results from the interaction of turbulent convection with rotation. The investigation into the turbulent mechanisms of angular-momentum transport has reached a level at which the obtained results can serve as the basis for developing quantitative models of stellar rotation. Such models contain virtually no free parameters but closely reproduce the helioseismological data on the internal rotation of the Sun. The theoretical predictions on the differential rotation of the stars agree with observations. A brief discussion is held here on the relation between the magnetic activity of stars and the nonuniformity of their rotation and on prospects for further development of the theory.

PROGRESS REPORT ON THE DSSTOX DATABASE NETWORK: NEWLY LAUNCHED WEBSITE, APPLICATIONS, FUTURE PLANS

EPA Science Inventory

Progress Report on the DSSTox Database Network: Newly Launched Website, Applications, Future Plans

Progress will be reported on development of the Distributed Structure-Searchable Toxicity (DSSTox) Database Network and the newly launched public website that coordinates and...

Chirality and angular momentum in optical radiation

NASA Astrophysics Data System (ADS)

Coles, Matt M.; Andrews, David L.

2012-06-01

This paper develops, in precise quantum electrodynamic terms, photonic attributes of the “optical chirality density,” one of several measures long known to be conserved quantities for a vacuum electromagnetic field. The analysis lends insights into some recent interpretations of chiroptical experiments, in which this measure, and an associated chirality flux, have been treated as representing physically distinctive “superchiral” phenomena. In the fully quantized formalism the chirality density is promoted to operator status, whose exploration with reference to an arbitrary polarization basis reveals relationships to optical angular momentum and helicity operators. Analyzing multimode beams with complex wave-front structures, notably Laguerre-Gaussian modes, affords a deeper understanding of the interplay between optical chirality and optical angular momentum. By developing theory with due cognizance of the photonic character of light, it emerges that only the spin-angular momentum of light is engaged in such observations. Furthermore, it is shown that these prominent measures of the helicity of chiral electromagnetic radiation have a common basis in differences between the populations of optical modes associated with angular momenta of opposite sign. Using a calculation of the rate of circular dichroism as an example, with coherent states to model the electromagnetic field, it is discovered that two terms contribute to the differential effect. The primary contribution relates to the difference in left- and right-handed photon populations; the only other contribution, which displays a sinusoidal distance dependence corresponding to the claim of nodal enhancements, is connected with the quantum photon number-phase uncertainty relation. From the full analysis, it appears that the term “superchiral” can be considered redundant.

Medium and Small Aperture Speckle Interferometry for Geostationary On-Orbit-Servicing Space Surveillance

NASA Astrophysics Data System (ADS)

Scott, R.

On-Orbit-Servicing (OOS) in Geostationary Equatorial Orbit (GEO) is likely to become a space mission reality provoking new problems for the optical space surveillance community. OOS’ close-proximity flight of servicer and client satellites with separations less than 1 kilometer in GEO challenge the metric measurement capabilities of medium and small aperture space surveillance instruments. This paper describes an OOS monitoring technique based on Cross-Spectrum speckle interferometry to compensate for atmospheric turbulence and measure the OOS satellites’ differential relative position. Cross-Spectrum speckle interferometry, an astronomical technique developed to measure the astrometric positions of binary stars, was adapted to the geostationary OOS problem and was tested using Sloan i’ observations of co-located geostationary satellites. Medium (1.6m) and small (0.35m) aperture telescopes were used to observe these satellites undergoing optical conjunctions where their apparent line-of-sight separation narrowed within 5 arcseconds. During the initial development of the Cross-Spectrum approach some weaknesses were identified where particle strikes, faint background stars, anomalous fringe orientation angles and high relative angular rates corrupt the relative position measurement process. In this paper, newly adjusted compensation techniques to remedy these issues are described and the data is reprocessed. The Cross-Spectrum’s performance is shown to work well on closely-spaced GEO satellites with separations less than 3 arcseconds and evidence is shown suggesting the technique can measure satellite separations within 1.8 arcseconds.

Development of a Night Vision Goggle Heads-Up Display for Paratrooper Guidance

DTIC Science & Technology

2008-06-01

and GPS data [MIC07]. requiring altitude, position, velocity, acceleration, and angular rates for navigation or control. An internal GPS receiver...Language There are several programming languages that provide the operating capabilities for this program. Languages like JAVA and C# provide an...acceleration, and angular rates. Figure 3.6 illustrates the MIDG hardware’s input and output data. The sensor actually generates the INS data, which is

Knee Muscle Strength at Varying Angular Velocities and Associations with Gross Motor Function in Ambulatory Children with Cerebral Palsy

ERIC Educational Resources Information Center

Hong, Wei-Hsien; Chen, Hseih-Ching; Shen, I-Hsuan; Chen, Chung-Yao; Chen, Chia-Ling; Chung, Chia-Ying

2012-01-01

The aim of this study was to evaluate the relationships of muscle strength at different angular velocities and gross motor functions in ambulatory children with cerebral palsy (CP). This study included 33 ambulatory children with spastic CP aged 6-15 years and 15 children with normal development. Children with CP were categorized into level I (n =…

Angular intensity and polarization dependence of diffuse transmission through random media

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

Eliyahu, D.; Rosenbluh, M.; Feund, I.

1993-03-01

A simple theoretical model involving only a single sample parameter, the depolarization ratio [rho] for linearly polarized normally incident and normally scattered light, is developed to describe the angular intensity and all other polarization-dependent properties of diffuse transmission through multiple-scattering media. Initial experimental results that tend to support the theory are presented. Results for diffuse reflection are also described. 63 refs., 15 figs.

Kinematics of preferred and non-preferred handballing in Australian football.

PubMed

Parrington, Lucy; Ball, Kevin; MacMahon, Clare

2015-01-01

In Australian football (AF), handballing proficiently with both the preferred and non-preferred arm is important at elite levels; yet, little information is available for handballing on the non-preferred arm. This study compared preferred and non-preferred arm handballing techniques. Optotrak Certus (100 Hz) collected three-dimensional data for 19 elite AF players performing handballs with the preferred and non-preferred arms. Position data, range of motion (ROM), and linear and angular velocities were collected and compared between preferred and non-preferred arms using dependent t-tests. The preferred arm exhibited significantly greater forearm and humerus ROM and angular velocity and significantly greater shoulder angular velocity at ball contact compared to the non-preferred arm. In addition, the preferred arm produced a significantly greater range of lateral bend and maximum lower-trunk speed, maximum strike-side hip speed and hand speed at ball contact than the non-preferred arm. The non-preferred arm exhibited a significantly greater shoulder angle and lower- and upper-trunk orientation angle, but significantly lower support-elbow angle, trunk ROM, and trunk rotation velocity compared to the preferred arm. Reduced ROM and angular velocities found in non-preferred arm handballs indicates a reduction in the degrees of freedom and a less developed skill. Findings have implication for development of handballing on the non-preferred arm.

Speed-constrained three-axes attitude control using kinematic steering

NASA Astrophysics Data System (ADS)

Schaub, Hanspeter; Piggott, Scott

2018-06-01

Spacecraft attitude control solutions typically are torque-level algorithms that simultaneously control both the attitude and angular velocity tracking errors. In contrast, robotic control solutions are kinematic steering commands where rates are treated as the control variable, and a servo-tracking control subsystem is present to achieve the desired control rates. In this paper kinematic attitude steering controls are developed where an outer control loop establishes a desired angular response history to a tracking error, and an inner control loop tracks the commanded body angular rates. The overall stability relies on the separation principle of the inner and outer control loops which must have sufficiently different response time scales. The benefit is that the outer steering law response can be readily shaped to a desired behavior, such as limiting the approach angular velocity when a large tracking error is corrected. A Modified Rodrigues Parameters implementation is presented that smoothly saturates the speed response. A robust nonlinear body rate servo loop is developed which includes integral feedback. This approach provides a convenient modular framework that makes it simple to interchange outer and inner control loops to readily setup new control implementations. Numerical simulations illustrate the expected performance for an aggressive reorientation maneuver subject to an unknown external torque.

Mapping subsurface in proximity to newly-developed sinkhole along roadway.

DOT National Transportation Integrated Search

2013-02-01

MS&T acquired electrical resistivity tomography profiles in immediate proximity to a newly-developed sinkhole in Nixa Missouri : The sinkhole has closed a well-traveled municipal roadway and threatens proximal infrastructure. The intent of this inves...

A Markov Chain-based quantitative study of angular distribution of photons through turbid slabs via isotropic light scattering

NASA Astrophysics Data System (ADS)

Li, Xuesong; Northrop, William F.

2016-04-01

This paper describes a quantitative approach to approximate multiple scattering through an isotropic turbid slab based on Markov Chain theorem. There is an increasing need to utilize multiple scattering for optical diagnostic purposes; however, existing methods are either inaccurate or computationally expensive. Here, we develop a novel Markov Chain approximation approach to solve multiple scattering angular distribution (AD) that can accurately calculate AD while significantly reducing computational cost compared to Monte Carlo simulation. We expect this work to stimulate ongoing multiple scattering research and deterministic reconstruction algorithm development with AD measurements.

The rigid shell component for superrotation in planetary atmospheres: Angular momentum budget, mechanical analog and simulation of the spin up process

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Harris, I.

1981-01-01

An analysis of superrotation in the atmosphere of planets, with rotation axis perpendicular to the orbital plane is presented. As the atmosphere expands, Hadley cells develop producing a redistribution of mass and angular momentum. A three dimensional thermally driven zonally symmetric spectral model and Laplace transformation simulate the time evolution of a fluid leading from corotation under globally uniform heating to superrotation under globally nonuniform heating. For high viscosities the rigid shell component of atmospheric superrotation can be understood in analogy with a pirouette. During spin up angular momentum is transferred to the planet. For low iscosities, the process is reversed. A tendency toward geostrophy, combined with increase of surface pressure toward the poles (due to meridional mass transport), induces the atmosphere to subrotate temporarily at lower altitudes. Resultant viscous shear near the surface permits angular momentum to flow from the planet into the atmosphere propagating upwards to produce high altitude superrotation rates.

Tunable orbital angular momentum in high-harmonic generation

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

Gauthier, David; Ribič, P. Rebernik; Adhikary, G.

Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light–matter interactions,more » and the disentanglement and independent control of the intrinsic and extrinsic components of the photon’s angular momentum at short-wavelengths. Finally, the methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms.« less

Orbital and spin angular momentum in conical diffraction

NASA Astrophysics Data System (ADS)

Berry, M. V.; Jeffrey, M. R.; Mansuripur, M.

2005-11-01

The angular momentum Jinc of a light beam can be changed by passage through a slab of crystal. When the beam is incident along the optic axis of a biaxial crystal, which may also possess optical activity (chirality), the final angular momentum J can have both orbital (Jorb) and spin (Jsp) contributions, which we calculate paraxially exactly for arbitrary biaxiality and chirality and initially uniformly polarized beams with circular symmetry. For the familiar special case of a non-chiral crystal with fully developed conical-refraction rings, J is purely orbital and equal to Jinc/2, reflecting an interesting singularity structure in the beam. Explicit formulas and numerical computations are presented for a Gaussian incident beam. The change in angular momentum results in a torque on the crystal, along the axis of the incident beam. An additional, much larger, torque, about an axis lying in the slab, arises from the offset of the cone of conical refraction relative to the incident beam.

Bounded extremum seeking for angular velocity actuated control of nonholonomic unicycle

DOE PAGES

Scheinker, Alexander

2016-08-17

Here, we study control of the angular-velocity actuated nonholonomic unicycle, via a simple, bounded extremum seeking controller which is robust to external disturbances and measurement noise. The vehicle performs source seeking despite not having any position information about itself or the source, able only to sense a noise corrupted scalar value whose extremum coincides with the unknown source location. In order to control the angular velocity, rather than the angular heading directly, a controller is developed such that the closed loop system exhibits multiple time scales and requires an analysis approach expanding the previous work of Kurzweil, Jarnik, Sussmann, andmore » Liu, utilizing weak limits. We provide analytic proof of stability and demonstrate how this simple scheme can be extended to include position-independent source seeking, tracking, and collision avoidance of groups on autonomous vehicles in GPS-denied environments, based only on a measure of distance to an obstacle, which is an especially important feature for an autonomous agent.« less

Tunable orbital angular momentum in high-harmonic generation

DOE PAGES

Gauthier, David; Ribič, P. Rebernik; Adhikary, G.; ...

2017-04-05

Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light–matter interactions,more » and the disentanglement and independent control of the intrinsic and extrinsic components of the photon’s angular momentum at short-wavelengths. Finally, the methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms.« less

Controlled enhancement of spin-current emission by three-magnon splitting.

PubMed

Kurebayashi, Hidekazu; Dzyapko, Oleksandr; Demidov, Vladislav E; Fang, Dong; Ferguson, A J; Demokritov, Sergej O

2011-07-03

Spin currents--the flow of angular momentum without the simultaneous transfer of electrical charge--play an enabling role in the field of spintronics. Unlike the charge current, the spin current is not a conservative quantity within the conduction carrier system. This is due to the presence of the spin-orbit interaction that couples the spin of the carriers to angular momentum in the lattice. This spin-lattice coupling acts also as the source of damping in magnetic materials, where the precessing magnetic moment experiences a torque towards its equilibrium orientation; the excess angular momentum in the magnetic subsystem flows into the lattice. Here we show that this flow can be reversed by the three-magnon splitting process and experimentally achieve the enhancement of the spin current emitted by the interacting spin waves. This mechanism triggers angular momentum transfer from the lattice to the magnetic subsystem and modifies the spin-current emission. The finding illustrates the importance of magnon-magnon interactions for developing spin-current based electronics.

Multiscale Capability in Rattlesnake using Contiguous Discontinuous Discretization of Self-Adjoint Angular Flux Equation

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

Zheng, Weixiong; Wang, Yaqi; DeHart, Mark D.

2016-09-01

In this report, we present a new upwinding scheme for the multiscale capability in Rattlesnake, the MOOSE based radiation transport application. Comparing with the initial implementation of multiscale utilizing Lagrange multipliers to impose strong continuity of angular flux on interface of in-between subdomains, this scheme does not require the particular domain partitioning. This upwinding scheme introduces discontinuity of angular flux and resembles the classic upwinding technique developed for solving first order transport equation using discontinuous finite element method (DFEM) on the subdomain interfaces. Because this scheme restores the causality of radiation streaming on the interfaces, significant accuracy improvement can bemore » observed with moderate increase of the degrees of freedom comparing with the continuous method over the entire solution domain. Hybrid SN-PN is implemented and tested with this upwinding scheme. Numerical results show that the angular smoothing required by Lagrange multiplier method is not necessary for the upwinding scheme.« less

On measurement of acoustic pulse arrival angles using a vertical array

NASA Astrophysics Data System (ADS)

Makarov, D. V.

2017-11-01

We consider a recently developed method to analyze the angular structure of pulsed acoustic fields in an underwater sound channel. The method is based on the Husimi transform that allows us to approximately link a wave field with the corresponding ray arrivals. The advantage of the method lies in the possibility of its practical realization by a vertical hydrophone array crossing only a small part of the oceanic depth. The main aim of the present work is to find the optimal parameter values of the array that ensure good angular accuracy and sufficient reliability of the algorithm to calculate the arrival angles. Broadband pulses with central frequencies of 80 and 240 Hz are considered. It is shown that an array with a length of several hundred meters allows measuring the angular spectrum with an accuracy of up to 1 degree. The angular resolution is lowered with an increase of the sound wavelength due to the fundamental limitations imposed by the uncertainty relation.

Responses of primate caudal parabrachial nucleus and Kolliker-fuse nucleus neurons to whole body rotation

NASA Technical Reports Server (NTRS)

Balaban, Carey D.; McGee, David M.; Zhou, Jianxun; Scudder, Charles A.

2002-01-01

The caudal aspect of the parabrachial (PBN) and Kolliker-Fuse (KF) nuclei receive vestibular nuclear and visceral afferent information and are connected reciprocally with the spinal cord, hypothalamus, amygdala, and limbic cortex. Hence, they may be important sites of vestibulo-visceral integration, particularly for the development of affective responses to gravitoinertial challenges. Extracellular recordings were made from caudal PBN cells in three alert, adult female Macaca nemestrina through an implanted chamber. Sinusoidal and position trapezoid angular whole body rotation was delivered in yaw, roll, pitch, and vertical semicircular canal planes. Sites were confirmed histologically. Units that responded during rotation were located in lateral and medial PBN and KF caudal to the trochlear nerve at sites that were confirmed anatomically to receive superior vestibular nucleus afferents. Responses to whole-body angular rotation were modeled as a sum of three signals: angular velocity, a leaky integration of angular velocity, and vertical position. All neurons displayed angular velocity and integrated angular velocity sensitivity, but only 60% of the neurons were position-sensitive. These responses to vertical rotation could display symmetric, asymmetric, or fully rectified cosinusoidal spatial tuning about a best orientation in different cells. The spatial properties of velocity and integrated velocity and position responses were independent for all position-sensitive neurons; the angular velocity and integrated angular velocity signals showed independent spatial tuning in the position-insensitive neurons. Individual units showed one of three different orientations of their excitatory axis of velocity rotation sensitivity: vertical-plane-only responses, positive elevation responses (vertical plane plus ipsilateral yaw), and negative elevation axis responses (vertical plane plus negative yaw). The interactions between the velocity and integrated velocity components also produced variations in the temporal pattern of responses as a function of rotation direction. These findings are consistent with the hypothesis that a vestibulorecipient region of the PBN and KF integrates signals from the vestibular nuclei and relay information about changes in whole-body orientation to pathways that produce homeostatic and affective responses.

Innovations in Rheometer Controlled-Rate Control Loop Design: Ultra Low Angular Speed Control and New Applications

NASA Astrophysics Data System (ADS)

Schulz, Ulrich; Sierro, Philippe; Nijman, Jint

2008-07-01

The design and implementation of an angular speed control loop for a universal rheometer is not a trivial task. The combination of a highly dynamic, very low inertia (drag cup) motor (motor inertia is 10-5 kg m2) with samples which can range in viscosity from 10-3 Pas to 108 Pas, which can be between purely viscous and higly viscoelastic, which can exhibit yield-stresses, etc. asks for a highly adaptive digital control loop. For the HAAKE MARS rotational rheometer a new adaptive control loop was developed which allows the control of angular speeds as low 5×10-9 rad/s and response times a short as 10 ms. The adaptation of the control loop to "difficult" samples is performed by analysing the response of the complete system to a short pre-test. In this paper we will show that the (very) short response times at (very) low angular speeds are not only achieved with ideal samples, but due to the adaptable control loop, also with "difficult" samples. We will show measurement results on "difficult" samples like cosmetic creams and emulsions, a laponite gel, etc. to proof that angular speeds down to 10-4 rad/s are reached within 10 ms to 20 ms and angular speeds down to 10-7 rad/s within 1 s to 2 s. The response times for reaching ultra low angular speeds down to 5×10-9 rad/s are in the order of 10 s to 30 s. With this new control loop it is, for the first time, possible to measure yield stresses by applying a very low constant shear-rate to the sample and measuring the torque response as a function of time.

Evaluation of new binders using newly developed fracture energy test.

DOT National Transportation Integrated Search

2013-07-01

This study evaluated a total of seven asphalt binders with various additives : using the newly developed binder fracture energy test. The researchers prepared and : tested PAV-aged and RTFO-plus-PAV-aged specimens. This study confirmed previous : res...

13 CFR 120.812 - Probationary period for newly certified CDCs.

Code of Federal Regulations, 2013 CFR

2013-01-01

... certified CDCs. 120.812 Section 120.812 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Certification Procedures to Become A Cdc § 120.812 Probationary period for newly certified CDCs. (a) Newly certified CDCs will be on probation for a period of two...

13 CFR 120.812 - Probationary period for newly certified CDCs.

Code of Federal Regulations, 2014 CFR

2014-01-01

... certified CDCs. 120.812 Section 120.812 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Certification Procedures to Become A Cdc § 120.812 Probationary period for newly certified CDCs. (a) Newly certified CDCs will be on probation for a period of two...

13 CFR 120.812 - Probationary period for newly certified CDCs.

Code of Federal Regulations, 2012 CFR

2012-01-01

... certified CDCs. 120.812 Section 120.812 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Certification Procedures to Become A Cdc § 120.812 Probationary period for newly certified CDCs. (a) Newly certified CDCs will be on probation for a period of two...

13 CFR 120.812 - Probationary period for newly certified CDCs.

Code of Federal Regulations, 2011 CFR

2011-01-01

... certified CDCs. 120.812 Section 120.812 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Certification Procedures to Become A Cdc § 120.812 Probationary period for newly certified CDCs. (a) Newly certified CDCs will be on probation for a period of two...

The dynamical simulation of transient three-dimensional cryogenic liquid sloshing oscillations under low-gravity and microgravity

NASA Astrophysics Data System (ADS)

Chi, Yong Mann

A numerical simulation model has been developed for the dynamical behavior of spacecraft propellant, both during the draining and the closing of the tank outlet at the onset of suction dip affected by the asymmetric combined gravity gradient and gravity jitter accelerations. In particular the effect of the surface tension of the fluids in the partially filled dewar (applicable to the Gravity Probe-B spacecraft dewar tank and fuel tanks for a liquid rocket) with rotation has been simulated and investigated. Two different cases of accelerations, one with gravity jitter dominated and the other equally weighted between gravity gradient and gravity jitter accelerations, are studied. In the development of this numerical simulation model, the NASA-VOF3D has been used as a supplement to the numerical program of this dissertation. The NASA-VOF3D code has been used for performing the three-dimensional incompressible flows with free surface. This is also used for controlling liquid sloshing inside the tank when the spacecraft is orbiting. To keep track of the location of the liquid, the fractional volume of fluid (VOF) technique was used. The VOF is based on the indicator function of the region occupied by the liquid with an Eulerian approach to solve the free surface phenomena between liquid and gas phases. For the calculation of surface tension force, the VOF model is also used. The newly developed simulation model is used to investigate the characteristics of liquid hydrogen draining in terms of the residual amount of trapped liquid at the onset of the suction dip and residual liquid volume at the time the dip of the liquid-vapor interface formed. This investigation simulates the characteristics of liquid oscillations due to liquid container outlet shut-off at the onset of suction dip. These phenomena checked how these mechanisms affected the excitation of slosh waves during the course of liquid draining and after shut-off tank outlet. In the present study, the dynamical evolution of sloshing dynamics excited by fluid stress forces, fluid stress moments, and the arm of fluid moment exerted on the dewar container, is considered. This excitation was driven by the combined gravity gradient and gravity jitter acceleration inside the tank during the draining process and closing the tank outlet. The time evolution of the liquid-vapor interface profiles and the bubble mass center fluctuation, as well as liquid mass center and fluctuations of angular momentum caused by slosh wave excitations with 0.1 rpm in a reduced gravity, are also investigated and simulated. Force, angular momentum, and torque vector time histories and Power Spectral Density (PSD) are also plotted and discussed. The results of this investigation may be applied to determine the magnitude and nature of control forces and torques needed to minimize influence of slosh on the dynamics of liquid fueled vehicles in near earth orbit. Results show that induced fluid forces (or angular momentum) exerted on the container wall along x and y-axes, which are non-existent at the beginning, are introduced by the slosh waves excited by asymmetric gravity gradient and the gravity jitter acceleration.

Characterization of the angular memory effect of scattered light in biological tissues.

PubMed

Schott, Sam; Bertolotti, Jacopo; Léger, Jean-Francois; Bourdieu, Laurent; Gigan, Sylvain

2015-05-18

High resolution optical microscopy is essential in neuroscience but suffers from scattering in biological tissues and therefore grants access to superficial brain layers only. Recently developed techniques use scattered photons for imaging by exploiting angular correlations in transmitted light and could potentially increase imaging depths. But those correlations ('angular memory effect') are of a very short range and should theoretically be only present behind and not inside scattering media. From measurements on neural tissues and complementary simulations, we find that strong forward scattering in biological tissues can enhance the memory effect range and thus the possible field-of-view by more than an order of magnitude compared to isotropic scattering for ∼1 mm thick tissue layers.

A tidal theory for the origin of the solar nebula

NASA Technical Reports Server (NTRS)

Kobrick, M.; Kaula, W. M.

1979-01-01

A model for the origin of the solar nebula is developed with attention to the significance of angular momentum considerations. Evidence that stars are born in groups rather than singly is examined. It is shown that protostars which are members of typical galactic clusters have some probability of undergoing a gravitational encounter with another star while they are collapsing. According to the model, these encounters impart disproportionate amounts of angular momentum to the later material to fall in toward already centrally condensed fragments. The amount of central condensation of a fragment is the overriding factor in determining its stability against destruction by tidal forces. The encounter also imparts angular momentum to matter that is still accreting onto the protosun.

Phase Resolved Angular Velocity Control of Cross Flow Turbines

NASA Astrophysics Data System (ADS)

Strom, Benjamin; Brunton, Steven; Polagye, Brian

2015-11-01

Cross flow turbines have a number of operational advantages for the conversion of kinetic energy in marine or fluvial currents, but they are often less efficient than axial flow devices. Here a control scheme is presented in which the angular velocity of a cross flow turbine with two straight blades is prescribed as a function of azimuthal blade position, altering the time-varying effective angle of attack. Flume experiments conducted with a scale model turbine show approximately an 80% increase in turbine efficiency versus optimal constant angular velocity and constant resistive torque control schemes. Torque, drag, and lateral forces on one- and two-bladed turbines are analyzed and interpreted with bubble flow visualization to develop a simple model that describes the hydrodynamics responsible for the observed increase in mean efficiency. Challenges associated with implementing this control scheme on commercial-scale devices are discussed. If solutions are found, the performance increase presented here may impact the future development of cross flow turbines.

Semiclassical multi-phonon theory for atom-surface scattering: Application to the Cu(111) system

NASA Astrophysics Data System (ADS)

Daon, Shauli; Pollak, Eli

2015-05-01

The semiclassical perturbation theory of Hubbard and Miller [J. Chem. Phys. 80, 5827 (1984)] is further developed to include the full multi-phonon transitions in atom-surface scattering. A practically applicable expression is developed for the angular scattering distribution by utilising a discretized bath of oscillators, instead of the continuum limit. At sufficiently low surface temperature good agreement is found between the present multi-phonon theory and the previous one-, and two-phonon theory derived in the continuum limit in our previous study [Daon, Pollak, and Miret-Artés, J. Chem. Phys. 137, 201103 (2012)]. The theory is applied to the measured angular distributions of Ne, Ar, and Kr scattered from a Cu(111) surface. We find that the present multi-phonon theory substantially improves the agreement between experiment and theory, especially at the higher surface temperatures. This provides evidence for the importance of multi-phonon transitions in determining the angular distribution as the surface temperature is increased.

Theory of free electron vortices

PubMed Central

Schattschneider, P.; Verbeeck, J.

2011-01-01

The recent creation of electron vortex beams and their first practical application motivates a better understanding of their properties. Here, we develop the theory of free electron vortices with quantized angular momentum, based on solutions of the Schrödinger equation for cylindrical boundary conditions. The principle of transformation of a plane wave into vortices with quantized angular momentum, their paraxial propagation through round magnetic lenses, and the effect of partial coherence are discussed. PMID:21930017

Angular Superresolution for a Scanning Antenna with Simulated Complex Scatterer-Type Targets

DTIC Science & Technology

2002-05-01

Approved for public release; distribution unlimited. The Scan- MUSIC (MUltiple SIgnal Classification), or SMUSIC, algorithm was developed by the Millimeter...with the use of a single rotatable sensor scanning in an angular region of interest. This algorithm has been adapted and extended from the MUSIC ...simulation. Abstract ii iii Contents 1. Introduction 1 2. Extension of the MUSIC Algorithm for Scanning Antenna 2 2.1 Subvector Averaging Method

Development of Rolling Schedules for Equal Channel Angular Extrusion (ECAE)-Processed AZ31 Magnesium Alloy

DTIC Science & Technology

2016-04-01

Processed AZ31 Magnesium Alloy Sheet by Laszlo J Kecskes, Vincent H Hammond, Michael Eichhorst, Norman Herzig, and Lothar Meyer...Angular Extrusion (ECAE)–Processed AZ31 Magnesium Alloy Sheet by Laszlo J Kecskes and Vincent H Hammond Weapons and Materials Research...successfully reduced into 1.5-mm-thick sheets . Two sets of plates, each with a different texture type, were evaluated. Microscopic examination of

Leaf area and photosynthesis of newly emerged trifoliolate leaves are regulated by mature leaves in soybean.

PubMed

Wu, Yushan; Gong, Wanzhuo; Wang, Yangmei; Yong, Taiwen; Yang, Feng; Liu, Weigui; Wu, Xiaoling; Du, Junbo; Shu, Kai; Liu, Jiang; Liu, Chunyan; Yang, Wenyu

2018-03-29

Leaf anatomy and the stomatal development of developing leaves of plants have been shown to be regulated by the same light environment as that of mature leaves, but no report has yet been written on whether such a long-distance signal from mature leaves regulates the total leaf area of newly emerged leaves. To explore this question, we created an investigation in which we collected data on the leaf area, leaf mass per area (LMA), leaf anatomy, cell size, cell number, gas exchange and soluble sugar content of leaves from three soybean varieties grown under full sunlight (NS), shaded mature leaves (MS) or whole plants grown in shade (WS). Our results show that MS or WS cause a marked decline both in leaf area and LMA in newly developing leaves. Leaf anatomy also showed characteristics of shade leaves with decreased leaf thickness, palisade tissue thickness, sponge tissue thickness, cell size and cell numbers. In addition, in the MS and WS treatments, newly developed leaves exhibited lower net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (E), but higher carbon dioxide (CO 2 ) concentration in the intercellular space (Ci) than plants grown in full sunlight. Moreover, soluble sugar content was significantly decreased in newly developed leaves in MS and WS treatments. These results clearly indicate that (1) leaf area, leaf anatomical structure, and photosynthetic function of newly developing leaves are regulated by a systemic irradiance signal from mature leaves; (2) decreased cell size and cell number are the major cause of smaller and thinner leaves in shade; and (3) sugars could possibly act as candidate signal substances to regulate leaf area systemically.

Angular Multigrid Preconditioner for Krylov-Based Solution Techniques Applied to the Sn Equations with Highly Forward-Peaked Scattering

NASA Astrophysics Data System (ADS)

Turcksin, Bruno; Ragusa, Jean C.; Morel, Jim E.

2012-01-01

It is well known that the diffusion synthetic acceleration (DSA) methods for the Sn equations become ineffective in the Fokker-Planck forward-peaked scattering limit. In response to this deficiency, Morel and Manteuffel (1991) developed an angular multigrid method for the 1-D Sn equations. This method is very effective, costing roughly twice as much as DSA per source iteration, and yielding a maximum spectral radius of approximately 0.6 in the Fokker-Planck limit. Pautz, Adams, and Morel (PAM) (1999) later generalized the angular multigrid to 2-D, but it was found that the method was unstable with sufficiently forward-peaked mappings between the angular grids. The method was stabilized via a filtering technique based on diffusion operators, but this filtering also degraded the effectiveness of the overall scheme. The spectral radius was not bounded away from unity in the Fokker-Planck limit, although the method remained more effective than DSA. The purpose of this article is to recast the multidimensional PAM angular multigrid method without the filtering as an Sn preconditioner and use it in conjunction with the Generalized Minimal RESidual (GMRES) Krylov method. The approach ensures stability and our computational results demonstrate that it is also significantly more efficient than an analogous DSA-preconditioned Krylov method.

Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

NASA Technical Reports Server (NTRS)

Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dunner, R.; Essinger-Hileman, T.; Eimer, J.;

Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

NASA Astrophysics Data System (ADS)

Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dünner, R.; Essinger-Hileman, T.; Eimer, J.; Fluxa, P.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G.; Hubmayr, J.; Iuliano, J.; Marriage, T. A.; Miller, N.; Moseley, S. H.; Mumby, G.; Petroff, M.; Reintsema, C.; Rostem, K.; U-Yen, K.; Watts, D.; Wagner, E.; Wollack, E. J.; Xu, Z.; Zeng, L.

2016-08-01

The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe ˜ 70 % of the sky. A variable-delay polarization modulator provides modulation of the polarization at ˜ 10 Hz to suppress the 1/ f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.

Direct observation of temperature-driven magnetic symmetry transitions by vectorial resolved MOKE magnetometry

NASA Astrophysics Data System (ADS)

Cuñado, Jose Luis F.; Pedrosa, Javier; Ajejas, Fernando; Perna, Paolo; Miranda, Rodolfo; Camarero, Julio

2017-10-01

Angle- and temperature-dependent vectorial magnetometry measurements are necessary to disentangle the effective magnetic symmetry in magnetic nanostructures. Here we present a detailed study on an Fe(1 0 0) thin film system with competing collinear biaxial (four-fold symmetry) and uniaxial (two-fold) magnetic anisotropies, carried out with our recently developed full angular/broad temperature range/vectorial-resolved magneto-optical Kerr effect magnetometer, named TRISTAN. The data give direct views on the angular and temperature dependence of the magnetization reversal pathways, from which characteristic axes, remanences, critical fields, domain wall types, and effective magnetic symmetry are obtained. In particular, although the remanence shows four-fold angular symmetry for all investigated temperatures (15 K-400 K), the critical fields show strong temperature and angular dependencies and the reversal mechanism changes for specific angles at a given (angle-dependent) critical temperature, showing signatures of an additional collinear two-fold symmetry. This symmetry-breaking is more relevant as temperature increases to room temperature. It originates from the competition between two anisotropy contributions with different symmetry and temperature evolution. The results highlight the importance of combining temperature and angular studies, and the need to look at different magnetic parameters to unravel the underlying magnetic symmetries and temperature evolutions of the symmetry-breaking effects in magnetic nanostructures.

Testing vision with angular and radial multifocal designs using Adaptive Optics.

PubMed

Vinas, Maria; Dorronsoro, Carlos; Gonzalez, Veronica; Cortes, Daniel; Radhakrishnan, Aiswaryah; Marcos, Susana

2017-03-01

Multifocal vision corrections are increasingly used solutions for presbyopia. In the current study we have evaluated, optically and psychophysically, the quality provided by multizone radial and angular segmented phase designs. Optical and relative visual quality were evaluated using 8 subjects, testing 6 phase designs. Optical quality was evaluated by means of Visual Strehl-based-metrics (VS). The relative visual quality across designs was obtained through a psychophysical paradigm in which images viewed through 210 pairs of phase patterns were perceptually judged. A custom-developed Adaptive Optics (AO) system, including a Hartmann-Shack sensor and an electromagnetic deformable mirror, to measure and correct the eye's aberrations, and a phase-only reflective Spatial Light Modulator, to simulate the phase designs, was developed for this study. The multizone segmented phase designs had 2-4 zones of progressive power (0 to +3D) in either radial or angular distributions. The response of an "ideal observer" purely responding on optical grounds to the same psychophysical test performed on subjects was calculated from the VS curves, and compared with the relative visual quality results. Optical and psychophysical pattern-comparison tests showed that while 2-zone segmented designs (angular & radial) provided better performance for far and near vision, 3- and 4-zone segmented angular designs performed better for intermediate vision. AO-correction of natural aberrations of the subjects modified the response for the different subjects but general trends remained. The differences in perceived quality across the different multifocal patterns are, in a large extent, explained by optical factors. AO is an excellent tool to simulate multifocal refractions before they are manufactured or delivered to the patient, and to assess the effects of the native optics to their performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optical vibration measurement of mechatronics devices

NASA Astrophysics Data System (ADS)

Yanabe, Shigeo

1993-09-01

An optical vibration measuring system which enables to detect both linear and angular displacement of 25 nm and 5 prad was developed. The system is mainly composed of a He-Ne laser, a displacement detecting photo-diode and lenses, and has linear and angular displacement magnification mechanism using two different principles of optical lever. The system was applied to measure vibrational characteristics of magnetic head slider of hard disk drives and to measure stator teeth driving velocities of ultrasonic motor.

Kinematic analysis of crank -cam mechanism of process equipment

NASA Astrophysics Data System (ADS)

Podgornyj, Yu I.; Skeeba, V. Yu; Martynova, T. G.; Pechorkina, N. S.; Skeeba, P. Yu

2018-03-01

This article discusses how to define the kinematic parameters of a crank-cam mechanism. Using the mechanism design, the authors have developed a calculation model and a calculation algorithm that allowed the definition of kinematic parameters of the mechanism, including crank displacements, angular velocities and acceleration, as well as driven link (rocker arm) angular speeds and acceleration. All calculations were performed using the Mathcad mathematical package. The results of the calculations are reported as numerical values.

Inversion of particle-size distribution from angular light-scattering data with genetic algorithms.

PubMed

Ye, M; Wang, S; Lu, Y; Hu, T; Zhu, Z; Xu, Y

1999-04-20

A stochastic inverse technique based on a genetic algorithm (GA) to invert particle-size distribution from angular light-scattering data is developed. This inverse technique is independent of any given a priori information of particle-size distribution. Numerical tests show that this technique can be successfully applied to inverse problems with high stability in the presence of random noise and low susceptibility to the shape of distributions. It has also been shown that the GA-based inverse technique is more efficient in use of computing time than the inverse Monte Carlo method recently developed by Ligon et al. [Appl. Opt. 35, 4297 (1996)].

Development of Magneto-Resistive Angular Position Sensors for Space Applications

NASA Astrophysics Data System (ADS)

Hahn, Robert; Langendorf, Sven; Seifart, Klaus; Slatter, Rolf; Olberts, Bastian; Romera, Fernando

2015-09-01

Magnetic microsystems in the form of magneto- resistive (MR) sensors are firmly established in automobiles and industrial applications. They measure path, angle, electrical current, or magnetic fields. MR technology opens up new sensor possibilities in space applications and can be an enabling technology for optimal performance, high robustness and long lifetime at reasonable costs. In a recent assessment study performed by HTS GmbH and Sensitec GmbH under ESA Contract a market survey has confirmed that space industry has a very high interest in novel, contactless position sensors based on MR technology. Now, a detailed development stage is pursued, to advance the sensor design up to Engineering Qualification Model (EQM) level and to perform qualification testing for a representative pilot space application.The paper briefly reviews the basics of magneto- resistive effects and possible sensor applications and describes the key benefits of MR angular sensors with reference to currently operational industrial and space applications. The results of the assessment study are presented and potential applications and uses of contactless magneto-resistive angular sensors for spacecraft are identified. The baseline mechanical and electrical sensor design will be discussed. An outlook on the EQM development and qualification tests is provided.

Single crystal metal wedges for surface acoustic wave propagation

DOEpatents

Fisher, E.S.

1980-05-09

An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

Single crystal metal wedges for surface acoustic wave propagation

DOEpatents

Fisher, Edward S.

1982-01-01

An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

CHARRON: Code for High Angular Resolution of Rotating Objects in Nature

NASA Astrophysics Data System (ADS)

Domiciano de Souza, A.; Zorec, J.; Vakili, F.

2012-12-01

Rotation is one of the fundamental physical parameters governing stellar physics and evolution. At the same time, spectrally resolved optical/IR long-baseline interferometry has proven to be an important observing tool to measure many physical effects linked to rotation, in particular, stellar flattening, gravity darkening, differential rotation. In order to interpret the high angular resolution observations from modern spectro-interferometers, such as VLTI/AMBER and VEGA/CHARA, we have developed an interferometry-oriented numerical model: CHARRON (Code for High Angular Resolution of Rotating Objects in Nature). We present here the characteristics of CHARRON, which is faster (≃q10-30 s per model) and thus more adapted to model-fitting than the first version of the code presented by Domiciano de Souza et al. (2002).

The Sub-bureau for Atmospheric Angular Momentum of the International Earth Rotation Service - A meteorological data center with geodetic applications

NASA Technical Reports Server (NTRS)

Salstein, David A.; Kann, Deirdre M.; Miller, Alvin J.; Rosen, Richard D.

1993-01-01

By exchanging angular momentum with the solid portion of the earth, the atmosphere plays a vital role in exciting small but measurable changes in the rotation of our planet. Recognizing this relationship, the International Earth Rotation Service invited the U.S. National Meteorological Center to organize a Sub-bureau for Atmospheric Angular Momentum (SBAAM) for the purpose of collecting, distributing, archiving, and analyzing atmospheric parameters relevant to earth rotation/polar motion. These functions of wind and surface pressure are being computed with data from several of the world's weather services, and they are being widely applied to the research and operations of the geodetic community. The SBAAM began operating formally in October 1989, and this article highlights its development, operations, and significance.

Comparisons of angularly and spectrally resolved Bremsstrahlung measurements to two-dimensional multi-stage simulations of short-pulse laser-plasma interactions

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

Chen, C. D.; Kemp, A. J.; Pérez, F.

2013-05-15

A 2-D multi-stage simulation model incorporating realistic laser conditions and a fully resolved electron distribution handoff has been developed and compared to angularly and spectrally resolved Bremsstrahlung measurements from high-Z planar targets. For near-normal incidence and 0.5-1 × 10{sup 20} W/cm{sup 2} intensity, particle-in-cell (PIC) simulations predict the existence of a high energy electron component consistently directed away from the laser axis, in contrast with previous expectations for oblique irradiation. Measurements of the angular distribution are consistent with a high energy component when directed along the PIC predicted direction, as opposed to between the target normal and laser axis asmore » previously measured.« less

Improved Modeling of Open Waveguide Aperture Radiators for use in Conformal Antenna Arrays

NASA Astrophysics Data System (ADS)

Nelson, Gregory James

Open waveguide apertures have been used as radiating elements in conformal arrays. Individual radiating element model patterns are used in constructing overall array models. The existing models for these aperture radiating elements may not accurately predict the array pattern for TEM waves which are not on boresight for each radiating element. In particular, surrounding structures can affect the far field patterns of these apertures, which ultimately affects the overall array pattern. New models of open waveguide apertures are developed here with the goal of accounting for the surrounding structure effects on the aperture far field patterns such that the new models make accurate pattern predictions. These aperture patterns (both E plane and H plane) are measured in an anechoic chamber and the manner in which they deviate from existing model patterns are studied. Using these measurements as a basis, existing models for both E and H planes are updated with new factors and terms which allow the prediction of far field open waveguide aperture patterns with improved accuracy. These new and improved individual radiator models are then used to predict overall conformal array patterns. Arrays of open waveguide apertures are constructed and measured in a similar fashion to the individual aperture measurements. These measured array patterns are compared with the newly modeled array patterns to verify the improved accuracy of the new models as compared with the performance of existing models in making array far field pattern predictions. The array pattern lobe characteristics are then studied for predicting fully circularly conformal arrays of varying radii. The lobe metrics that are tracked are angular location and magnitude as the radii of the conformal arrays are varied. A constructed, measured array that is close to conforming to a circular surface is compared with a fully circularly conformal modeled array pattern prediction, with the predicted lobe angular locations and magnitudes tracked, plotted and tabulated. The close match between the patterns of the measured array and the modeled circularly conformal array verifies the validity of the modeled circularly conformal array pattern predictions.

Characterization of a prototype MR-compatible Delta4 QA system in a 1.5 tesla MR-linac

NASA Astrophysics Data System (ADS)

de Vries, J. H. W.; Seravalli, E.; Houweling, A. C.; Woodings, S. J.; van Rooij, R.; Wolthaus, J. W. H.; Lagendijk, J. J. W.; Raaymakers, B. W.

2018-01-01

To perform patient plan quality assurance (QA) on a newly installed MR-linac (MRL) it is necessary to have an MR-compatible QA device. An MR compatible device (MR-Delta4) has been developed together with Scandidos AB (Uppsala, Sweden). The basic characteristics of the detector response, such as short-term reproducibility, dose linearity, field size dependency, dose rate dependency, dose-per-pulse dependency and angular dependency, were investigated for the clinical Delta4-PT as well as for the MR compatible version. All tests were performed with both devices on a conventional linac and the MR compatible device was tested on the MRL as well. No statistically significant differences were found in the short-term reproducibility (<0.1%), dose linearity (⩽0.5%), field size dependency (<2.0% for field sizes larger than 5  ×  5 cm2), dose rate dependency (<1.0%) or angular dependency for any phantom/linac combination. The dose-per-pulse dependency (<0.8%) was found to be significantly different between the two devices. This difference can be explained by the fact that the diodes in the clinical Delta4-PT were irradiated with a much larger dose than the MR-Delta4-PT ones. The absolute difference between the devices (<0.5%) was found to be small, so no clinical impact is expected. For both devices, the results were consistent with the characteristics of the Delta4-PT device reported in the literature (Bedford et al 2009 Phys. Med. Biol. 54 N167-76 Sadagopan et al 2009 J. Appl. Clin. Med. Phys. 10 2928). We found that the characteristics of the MR compatible Delta4 phantom were found to be comparable to the clinically used one. Also, the found characteristics do not differ from the previously reported characteristics of the commercially available non-MR compatible Delta4-PT phantom. Therefore, the MR compatible Delta4 prototype was found to be safe and effective for use in the 1.5 tesla magnetic field of the Elekta MR-linac

LAMMPS framework for dynamic bonding and an application modeling DNA

NASA Astrophysics Data System (ADS)

Svaneborg, Carsten

2012-08-01

We have extended the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to support directional bonds and dynamic bonding. The framework supports stochastic formation of new bonds, breakage of existing bonds, and conversion between bond types. Bond formation can be controlled to limit the maximal functionality of a bead with respect to various bond types. Concomitant with the bond dynamics, angular and dihedral interactions are dynamically introduced between newly connected triplets and quartets of beads, where the interaction type is determined from the local pattern of bead and bond types. When breaking bonds, all angular and dihedral interactions involving broken bonds are removed. The framework allows chemical reactions to be modeled, and use it to simulate a simplistic, coarse-grained DNA model. The resulting DNA dynamics illustrates the power of the present framework. Catalogue identifier: AEME_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEME_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public Licence No. of lines in distributed program, including test data, etc.: 2 243 491 No. of bytes in distributed program, including test data, etc.: 771 Distribution format: tar.gz Programming language: C++ Computer: Single and multiple core servers Operating system: Linux/Unix/Windows Has the code been vectorized or parallelized?: Yes. The code has been parallelized by the use of MPI directives. RAM: 1 Gb Classification: 16.11, 16.12 Nature of problem: Simulating coarse-grain models capable of chemistry e.g. DNA hybridization dynamics. Solution method: Extending LAMMPS to handle dynamic bonding and directional bonds. Unusual features: Allows bonds to be created and broken while angular and dihedral interactions are kept consistent. Additional comments: The distribution file for this program is approximately 36 Mbytes and therefore is not delivered directly when download or E-mail is requested. Instead an html file giving details of how the program can be obtained is sent. Running time: Hours to days. The examples provided in the distribution take just seconds to run.

Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance

PubMed Central

Lee, Chan-Bok; Eun, Denny; Kim, Kang-Ho; Park, Jae-Wan; Jee, Yong-Seok

2017-01-01

Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints. PMID:28503531

Regionally variant collagen alignment correlates with viscoelastic properties of the disc of the human temporomandibular joint.

PubMed

Gutman, Shawn; Kim, Daniel; Tarafder, Solaiman; Velez, Sergio; Jeong, Julia; Lee, Chang H

2018-02-01

To determine the regionally variant quality of collagen alignment in human TMJ discs and its statistical correlation with viscoelastic properties. For quantitative analysis of the quality of collagen alignment, horizontal sections of human TMJ discs with Pricrosirius Red staining were imaged under circularly polarized microscopy. Mean angle and angular deviation of collagen fibers in each region were analyzed using a well-established automated image-processing for angular gradient. Instantaneous and relaxation moduli of each disc region were measured under stress-relaxation test both in tensile and compression. Then Spearman correlation analysis was performed between the angular deviation and the moduli. To understand the effect of glycosaminoglycans on the correlation, TMJ disc samples were treated by chondroitinase ABC (C-ABC). Our imaging processing analysis showed the region-variant direction of collagen alignment, consistently with previous findings. Interestingly, the quality of collagen alignment, not only the directions, was significantly different in between the regions. The angular deviation of fiber alignment in the anterior and intermediate regions were significantly smaller than the posterior region. Medial and lateral regions showed significantly bigger angular deviation than all the other regions. The regionally variant angular deviation values showed statistically significant correlation with the tensile instantaneous modulus and the relaxation modulus, partially dependent on C-ABC treatment. Our findings suggest the region-variant degree of collagen fiber alignment is likely attributed to the heterogeneous viscoelastic properties of TMJ disc that may have significant implications in development of regenerative therapy for TMJ disc. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance.

PubMed

Lee, Chan-Bok; Eun, Denny; Kim, Kang-Ho; Park, Jae-Wan; Jee, Yong-Seok

2017-04-01

Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints.

Constructing Practical Knowledge of Teaching: Eleven Newly Qualified Language Teachers' Discursive Agency

ERIC Educational Resources Information Center

Ruohotie-Lyhty, Maria

2011-01-01

This paper explores the professional development of 11 newly qualified foreign language teachers. It draws on a qualitative longitudinal study conducted at the University of Jyvaskyla, Finland between 2002 and 2009. The paper concentrates on the personal side of teacher development by analysing participants' discourses concerning language…

A Major Unconformity Between Permian and Triassic Strata at Cape Kekurnoi, Alaska Peninsula: Old and New Observations on Stratigraphy and Hydrocarbon Potential

USGS Publications Warehouse

Blodgett, Robert B.; Sralla, Bryan

2008-01-01

A major angular unconformity separates carbonates and shales of the Upper Triassic Kamishak Formation from an underlying unnamed sequence of Permian agglomerate, volcaniclastic rocks (sandstone), and limestone near Puale Bay on the Alaska Peninsula. For the first time, we photographically document the angular unconformity in outcrop, as clearly exposed in a seacliff ~1.3 mi (2.1 km) west of Cape Kekurnoi in the Karluk C?4 and C?5 1:63,360-scale quadrangles. This unconformity is also documented by examination of core chips, ditch cuttings, and (or) open-hole electrical logs in two deep oil-and-gas-exploration wells (Humble Oil & Refining Co.?s Bear Creek No. 1 and Standard Oil Co. of California?s Grammer No. 1) drilled along the Alaska Peninsula southwest of Puale Bay. A third well (Richfield Oil Corp.?s Wide Bay Unit No. 1), south of and structurally on trend with the other two wells, probed deeply into the Paleozoic basement, but Triassic strata are absent, owing to either a major unconformity or a large fault. Here we briefly review current and newly acquired data on Permian and Triassic rocks of the Puale Bay-Becharof Lake-Wide Bay area on the basis of an examination of surface and subsurface materials. The resulting reinterpretation of the Permian and Triassic stratigraphy has important economic ramifications for oil and gas exploration on the Alaska Peninsula and in the Cook Inlet basin. We also present a history of petroleum exploration targeting Upper Triassic reservoirs in the region.

A Novel Optical/digital Processing System for Pattern Recognition

NASA Technical Reports Server (NTRS)

Boone, Bradley G.; Shukla, Oodaye B.

1993-01-01

This paper describes two processing algorithms that can be implemented optically: the Radon transform and angular correlation. These two algorithms can be combined in one optical processor to extract all the basic geometric and amplitude features from objects embedded in video imagery. We show that the internal amplitude structure of objects is recovered by the Radon transform, which is a well-known result, but, in addition, we show simulation results that calculate angular correlation, a simple but unique algorithm that extracts object boundaries from suitably threshold images from which length, width, area, aspect ratio, and orientation can be derived. In addition to circumventing scale and rotation distortions, these simulations indicate that the features derived from the angular correlation algorithm are relatively insensitive to tracking shifts and image noise. Some optical architecture concepts, including one based on micro-optical lenslet arrays, have been developed to implement these algorithms. Simulation test and evaluation using simple synthetic object data will be described, including results of a study that uses object boundaries (derivable from angular correlation) to classify simple objects using a neural network.

Angular coherence in ultrasound imaging: Theory and applications

PubMed Central

Li, You Leo; Dahl, Jeremy J.

2017-01-01

The popularity of plane-wave transmits at multiple transmit angles for synthetic transmit aperture (or coherent compounding) has spawned a number of adaptations and new developments of ultrasonic imaging. However, the coherence properties of backscattered signals with plane-wave transmits at different angles are unknown and may impact a subset of these techniques. To provide a framework for the analysis of the coherence properties of such signals, this article introduces the angular coherence theory in medical ultrasound imaging. The theory indicates that the correlation function of such signals forms a Fourier transform pair with autocorrelation function of the receive aperture function. This conclusion can be considered as an extended form of the van Cittert Zernike theorem. The theory is validated with simulation and experimental results obtained on speckle targets. On the basis of the angular coherence of the backscattered wave, a new short-lag angular coherence beamformer is proposed and compared with an existing spatial-coherence-based beamformer. An application of the theory in phase shift estimation and speed of sound estimation is also presented. PMID:28372139

X-Ray Diffractive Optics

NASA Technical Reports Server (NTRS)

Dennis, Brian; Li, Mary; Skinner, Gerald

2013-01-01

X-ray optics were fabricated with the capability of imaging solar x-ray sources with better than 0.1 arcsecond angular resolution, over an order of magnitude finer than is currently possible. Such images would provide a new window into the little-understood energy release and particle acceleration regions in solar flares. They constitute one of the most promising ways to probe these regions in the solar atmosphere with the sensitivity and angular resolution needed to better understand the physical processes involved. A circular slit structure with widths as fine as 0.85 micron etched in a silicon wafer 8 microns thick forms a phase zone plate version of a Fresnel lens capable of focusing approx. =.6 keV x-rays. The focal length of the 3-cm diameter lenses is 100 microns, and the angular resolution capability is better than 0.1 arcsecond. Such phase zone plates were fabricated in Goddard fs Detector Development Lab. (DDL) and tested at the Goddard 600-microns x-ray test facility. The test data verified that the desired angular resolution and throughput efficiency were achieved.

Developing Soft-Kill Capability for Light Armoured Vehicles through Battlefield Simulations

DTIC Science & Technology

2007-02-01

scripted so they can move, fire, sense, communicate and react without operator intervention. The entities, can interact with each other as well as manned...trace of the laser illuminator. The horizontal scan is 135◦ followed by a vertical angular displacement of 15◦ and retracement. The 15◦ vertical scan...properties based on combined characteristics. An example of a new detector is the laser detecting HARLID. With an angular resolution of ±1◦, it is a

Application for RSO Automated Proximity Analysis and IMAging (ARAPAJMA): Development of a Nanosat-based Space Situational Awareness Mission

DTIC Science & Technology

2013-08-05

preliminary design phase the operational modes defined here will be implemented in MATLAB/Simulink/Stateflow and will be used as a master mission script ...3. the detumble mode during which the nanosat uses the rate gyros of the IMU and its RCS thrusters to cancel the angular rates about each axis...the mode is exited nominally if the angular rate about each axis has been brought below a certain threshold, the largest solar panel has been pointed

Synthesis of a correcting filter with phase stabilization of the angular velocity of a synchronous motor by the feedback system method

NASA Technical Reports Server (NTRS)

Kazlauskas, K. A.; Kurlavichus, A. I.

1973-01-01

The operating characteristics of a synchronous electric motor are discussed. A system of phase stabilization of the instantaneous angular velocity of rotation of a synchronous-reaction motor is diagrammed. A mathematical model is developed to show the parameters which affect the operation of the motor. The selection of a correcting filter to use with the motor in order to reduce the reaction of the system to interference is explained.

The Saga of Light-Matter Interaction and Magneto-optical Effects Applications to Atomic Magnetometry, Laser-cooled Atoms, Atomic Clocks, Geomagnetism, and Plant Bio-magnetism

NASA Astrophysics Data System (ADS)

Corsini, Eric P.

The quest to expand the limited sensorial domain, in particular to bridge the inability to gauge magnetic fields near and far, has driven the fabrication of remedial tools. The interaction of ferromagnetic material with a magnetic field had been the only available technique to gauge that field for several millennium. The advent of electricity and associated classical phenomena captured in the four Maxwell equations, were a step forward. In the early 1900s, the model of quantum mechanics provided a two-way leap forward. One came from the newly understood interaction of light and matter, and more specifically the three-way coupling of photons, atoms' angular momenta, and magnetic field, which are the foundations of atomic magnetometry. The other came from magnetically sensitive quantum effects in a fabricated energy-ladder form of matter cooled to a temperature below that of the energy steps; these quantum effects gave rise to the superconducting quantum interference device (SQUID). Research using atomic magnetometers and SQUIDs has resulted in thousands of publications, text books, and conferences. The current status in each field is well described in Refs. [48,49,38,42] and all references therein. In this work we develop and investigate techniques and applications pertaining to atomic magnetometry. [Full text: eric.corsini gmail.com].

Low-spin structure of 51,35,86Br and 50,36,86Kr nuclei: The role of the g7 /2 neutron orbital

NASA Astrophysics Data System (ADS)

Urban, W.; Sieja, K.; Materna, T.; Czerwiński, M.; Rząca-Urban, T.; Blanc, A.; Jentschel, M.; Mutti, P.; Köster, U.; Soldner, T.; de France, G.; Simpson, G. S.; Ur, C. A.; Bernards, C.; Fransen, C.; Jolie, J.; Regis, J.-M.; Thomas, T.; Warr, N.

2016-10-01

Low-spin excited levels in 51,35,86Br and 50,36,86Kr, populated following β- decay and the neutron-induced fission of 235U, were measured using the Lohengrin fission-fragment separator and the EXILL array of Ge detectors at the PF1B cold-neutron facility of the Institute Laue-Langevin Grenoble. Improved populations of excited levels in 86Br remove inconsistencies existing in the literature on this nucleus. Directional-linear-polarization correlations, analyzed using newly developed formulas, as well as precise angular correlations allowed the unique 1- and 2- spin and parity assignments to the ground state of 86Br and the 4016.3-keV level in 86Kr, respectively. Based on these results we propose that the Gamow-Teller β- decays of 86Se and 86Br involve the ν g7 /2→π g9 /2 transition in addition to the ν p3 /2→π p3 /2 transition proposed earlier. In 86Kr we have identified 11+, 23+, and 31+ levels, analogous to the mixed-symmetry states in 94Mo, which in 86Kr are from proton excitations, only. Large-scale, shell-model calculations with refined interactions reproduce well excitations in 86Br and 86Kr and support our interpretations.

Molecular hydrogen solvated in water – A computational study

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

Śmiechowski, Maciej, E-mail: Maciej.Smiechowski@pg.gda.pl

2015-12-28

The aqueous hydrogen molecule is studied with molecular dynamics simulations at ambient temperature and pressure conditions, using a newly developed flexible and polarizable H{sub 2} molecule model. The design and implementation of this model, compatible with an existing flexible and polarizable force field for water, is presented in detail. The structure of the hydration layer suggests that first-shell water molecules accommodate the H{sub 2} molecule without major structural distortions and two-dimensional, radial-angular distribution functions indicate that as opposed to strictly tangential, the orientation of these water molecules is such that the solute is solvated with one of the free electronmore » pairs of H{sub 2}O. The calculated self-diffusion coefficient of H{sub 2}(aq) agrees very well with experimental results and the time dependence of mean square displacement suggests the presence of caging on a time scale corresponding to hydrogen bond network vibrations in liquid water. Orientational correlation function of H{sub 2} experiences an extremely short-scale decay, making the H{sub 2}–H{sub 2}O interaction potential essentially isotropic by virtue of rotational averaging. The inclusion of explicit polarizability in the model allows for the calculation of Raman spectra that agree very well with available experimental data on H{sub 2}(aq) under differing pressure conditions, including accurate reproduction of the experimentally noted trends with solute pressure or concentration.« less

Empirical force field-based kinetic Monte Carlo simulation of precipitate evolution and growth in Al-Cu alloys

NASA Astrophysics Data System (ADS)

Joshi, Kaushik; Chaudhuri, Santanu

2016-10-01

Ability to accelerate the morphological evolution of nanoscale precipitates is a fundamental challenge for atomistic simulations. Kinetic Monte Carlo (KMC) methodology is an effective approach for accelerating the evolution of nanoscale systems that are dominated by so-called rare events. The quality and accuracy of energy landscape used in KMC calculations can be significantly improved using DFT-informed interatomic potentials. Using newly developed computational framework that uses molecular simulator LAMMPS as a library function inside KMC solver SPPARKS, we investigated formation and growth of Guiner-Preston (GP) zones in dilute Al-Cu alloys at different temperature and copper concentrations. The KMC simulations with angular dependent potential (ADP) predict formation of coherent disc-shaped monolayers of copper atoms (GPI zones) in early stage. Such monolayers are then gradually transformed into energetically favored GPII phase that has two aluminum layers sandwiched between copper layers. We analyzed the growth kinetics of KMC trajectory using Johnson-Mehl-Avrami (JMA) theory and obtained a phase transformation index close to 1.0. In the presence of grain boundaries, the KMC calculations predict the segregation of copper atoms near the grain boundaries instead of formation of GP zones. The computational framework presented in this work is based on open source potentials and MD simulator and can predict morphological changes during the evolution of the alloys in the bulk and around grain boundaries.

Non-Invasive Imaging of Reactor Cores Using Cosmic Ray Muons

NASA Astrophysics Data System (ADS)

Milner, Edward

2011-10-01

Cosmic ray muons penetrate deeply in material, with some passing completely through very thick objects. This penetrating quality is the basis of two distinct, but related imaging techniques. The first measures the number of cosmic ray muons transmitted through parts of an object. Relatively fewer muons are absorbed along paths in which they encounter less material, compared to higher density paths, so the relative density of material is measured. This technique is called muon transmission imaging, and has been used to infer the density and structure of a variety of large masses, including mine overburden, volcanoes, pyramids, and buildings. In a second, more recently developed technique, the angular deflection of muons is measured by trajectory-tracking detectors placed on two opposing sides of an object. Muons are deflected more strongly by heavy nuclei, since multiple Coulomb scattering angle is approximately proportional to the nuclear charge. Therefore, a map showing regions of large deflection will identify the location of uranium in contrast to lighter nuclei. This technique is termed muon scattering tomography (MST) and has been developed to screen shipping containers for the presence of concealed nuclear material. Both techniques are a good way of non-invasively inspecting objects. A previously unexplored topic was applying MST to imaging large objects. Here we demonstrate extending the MST technique to the task of identifying relatively thick objects inside very thick shielding. We measured cosmic ray muons passing through a physical arrangement of material similar to a nuclear reactor, with thick concrete shielding and a heavy metal core. Newly developed algorithms were used to reconstruct an image of the ``mock reactor core,'' with resolution of approximately 30 cm.

Limited Angle Dual Modality Breast Imaging

NASA Astrophysics Data System (ADS)

More, Mitali J.; Li, Heng; Goodale, Patricia J.; Zheng, Yibin; Majewski, Stan; Popov, Vladimir; Welch, Benjamin; Williams, Mark B.

2007-06-01

We are developing a dual modality breast scanner that can obtain x-ray transmission and gamma ray emission images in succession at multiple viewing angles with the breast held under mild compression. These views are reconstructed and fused to obtain three-dimensional images that combine structural and functional information. Here, we describe the dual modality system and present results of phantom experiments designed to test the system's ability to obtain fused volumetric dual modality data sets from a limited number of projections, acquired over a limited (less than 180 degrees) angular range. We also present initial results from phantom experiments conducted to optimize the acquisition geometry for gamma imaging. The optimization parameters include the total number of views and the angular range over which these views should be spread, while keeping the total number of detected counts fixed. We have found that in general, for a fixed number of views centered around the direction perpendicular to the direction of compression, in-plane contrast and SNR are improved as the angular range of the views is decreased. The improvement in contrast and SNR with decreasing angular range is much greater for deeper lesions and for a smaller number of views. However, the z-resolution of the lesion is significantly reduced with decreasing angular range. Finally, we present results from limited angle tomography scans using a system with dual, opposing heads.

Muscle Contributions to Frontal Plane Angular Momentum during Walking

PubMed Central

Neptune, Richard R.; McGowan, Craig P.

2016-01-01

The regulation of whole-body angular momentum is important for maintaining dynamic balance during human walking, which is particularly challenging in the frontal plane. Whole-body angular momentum is actively regulated by individual muscle forces. Thus, understanding which muscles contribute to frontal plane angular momentum will further our understanding of mediolateral balance control and has the potential to help diagnose and treat balance disorders. The purpose of this study was to identify how individual muscles and gravity contribute to whole-body angular momentum in the frontal plane using a muscle-actuated forward dynamics simulation analysis. A three-dimensional simulation was developed that emulated the average walking mechanics of a group of young healthy adults (n=10). The results showed that a finite set of muscles are the primary contributors to frontal plane balance and that these contributions vary throughout the gait cycle. In early stance, the vasti, adductor magnus and gravity acted to rotate the body towards the contralateral leg while the gluteus medius acted to rotate the body towards the ipsilateral leg. In late stance, the gluteus medius continued to rotate the body towards the ipsilateral leg while the soleus and gastrocnemius acted to rotate the body towards the contralateral leg. These results highlight those muscles that are critical to maintaining dynamic balance in the frontal plane during walking and may provide targets for locomotor therapies aimed at treating balance disorders. PMID:27522538

Silicon pore optics for the international x-ray observatory

NASA Astrophysics Data System (ADS)

Wille, E.; Wallace, K.; Bavdaz, M.; Collon, M. J.; Günther, R.; Ackermann, M.; Beijersbergen, M. W.; Riekerink, M. O.; Blom, M.; Lansdorp, B.; de Vreede, L.

2017-11-01

Lightweight X-ray Wolter optics with a high angular resolution will enable the next generation of X-ray telescopes in space. The International X-ray Observatory (IXO) requires a mirror assembly of 3 m2 effective area (at 1.5 keV) and an angular resolution of 5 arcsec. These specifications can only be achieved with a novel technology like Silicon Pore Optics, which is developed by ESA together with a consortium of European industry. Silicon Pore Optics are made of commercial Si wafers using process technology adapted from the semiconductor industry. We present the manufacturing process ranging from single mirror plates towards complete focusing mirror modules mounted in flight configuration. The performance of the mirror modules is tested using X-ray pencil beams or full X-ray illumination. In 2009, an angular resolution of 9 arcsec was achieved, demonstrating the improvement of the technology compared to 17 arcsec in 2007. Further development activities of Silicon Pore Optics concentrate on ruggedizing the mounting system and performing environmental tests, integrating baffles into the mirror modules and assessing the mass production.

76 FR 33419 - Nationally Recognized Statistical Rating Organizations

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-08

... documentation of the internal control structure) or should the factors focus on the design (i.e., establishment... related to implementing them. a. Controls reasonably designed to ensure that a newly developed methodology... U.S.C. 78o-7(r)(1)(A). b. Controls reasonably designed to ensure that a newly developed methodology...

The Spelling Project. Technical Report 1992-2.

ERIC Educational Resources Information Center

Green, Kathy E.; Schroeder, David H.

Results of an analysis of a newly developed spelling test and several related measures are reported. Information about the reliability of a newly developed spelling test; its distribution of scores; its relationship with the standard battery of aptitude tests of the Johnson O'Connor Research Foundation; and its relationships with sex, age,…

How Schools Can Promote Healthy Development for Newly Arrived Immigrant and Refugee Adolescents: Research Priorities

ERIC Educational Resources Information Center

McNeely, Clea A.; Morland, Lyn; Doty, S. Benjamin; Meschke, Laurie L.; Awad, Summer; Husain, Altaf; Nashwan, Ayat

2017-01-01

Background: The US education system must find creative and effective ways to foster the healthy development of the approximately 2 million newly arrived immigrant and refugee adolescents, many of whom contend with language barriers, limited prior education, trauma, and discrimination. We identify research priorities for promoting the school…

The Bar Mode Instability in Deleptonizing Fizzlers

NASA Astrophysics Data System (ADS)

Imamura, James N.; Durisen, R. H.

2009-01-01

Core collapse in massive rotating nonmagnetic stars may hangup before neutron star densities are reached when rotationally supported or partially rotation supported, hot, lepton-rich objects known as fizzlers form. For typical massive core masses, fizzlers may form if the core has angular momentum J > 1049 g cm2 s-1. Newly formed fizzlers are stable to secular and dynamic nonaxisymmetric instabilities because of the high electron fraction per baryon, Ye > 0.3, and high entropy per baryon, Sn = 1-2 k of fizzler material, and the long-term evolution of a fizzler to neutron star density is driven by deleptonization and cooling of the lepton-rich fizzler material. Both processes lead to pressure loss which causes the fizzler to contract and spin-up. All deleptonizing fizzlers eventually become subject to gravito-rotation-driven nonaxisymmetric instabilities before they reach neutron star density. We study the development of barlike instabilities in deleptonizing fizzlers. We find that vigorous growth in barlike modes occurs only after the bar mode dynamic instability threshold is passed. Because barlike modes break axial symmetry, a burst of gravitational wave (GW) radiation is produced as barlike modes develop. For typical fizzler properties, the GW radiation will have frequency 300-600 Hz with strains of 10-23-10-23, for fizzlers at distances of 15 Mpc ( Virgo cluster of galaxies). Fizzlers in the Virgo cluster would be easily detectable by the gravitational wave obervatory LIGO if the barlike mode persisted for several hundred cycles. We find that barlike modes in fizzlers persist for at least 15-30 cycles in our simulations, depending on the deleptonization rate.

Spectroscopic CZT detectors development for x- and gamma-ray imaging instruments

NASA Astrophysics Data System (ADS)

Quadrini, Egidio M.; Uslenghi, Michela; Alderighi, Monica; Casini, Fabio; D'Angelo, Sergio; Fiorini, Mauro; La Palombara, Nicola; Mancini, Marcello; Monti, Serena; Bazzano, Angela; Di Cosimo, Sergio; Frutti, Massimo; Natalucci, Lorenzo; Ubertini, Pietro; Guadalupi, Giuseppe M.; Sassi, Matteo; Negri, Barbara

2007-09-01

In the context of R&D studies financed by the Italian Space Agency (ASI), a feasibility study to evaluate the Italian Industry interest in medium-large scale production of enhanced CZT detectors has been performed by an Italian Consortium. The R&D investment aims at providing in-house source of high quality solid state spectrometers for Space Astrophysics applications. As a possible spin-off industrial applications to Gamma-ray devices for non-destructive inspections in medical, commercial and security fields have been considered by ASI. The short term programme mainly consists of developing proprietary procedures for 2-3" CZT crystals growth, including bonding and contact philosophy, and a newly designed low-power electronics readout chain. The prototype design and breadboarding is based on a fast signal AD conversion with the target in order to perform a new run for an already existing low-power (<0.7 mW/pixel) ASIC. The prototype also provides digital photon energy reconstruction with particular care for multiple events and polarimetry evaluations. Scientific requirement evaluations for Space Astrophysics Satellite applications have been carried out in parallel, targeted to contribute to the ESA Cosmic Vision 2015-2025 Announcement of Opportunity. Detailed accommodation studies are undergoing, as part of this programme, to size a "Large area arcsecond angular resolution Imager" for the Gamma Ray Imager satellite (Knödlseder et al., this conference).and a new Gamma-ray Wide Field Camera for the "EDGE" proposal (Piro et al., this conference). Finally, an extended market study for cost analysis evaluation in view of the foreseen massive detector production has been performed.

Practices influenced by policy? An exploration of newly hired science teachers at sites in South Africa and the United States

NASA Astrophysics Data System (ADS)

Navy, S. L.; Luft, J. A.; Toerien, R.; Hewson, P. W.

2018-05-01

In many parts of the world, newly hired science teachers' practices are developing in a complex policy environment. However, little is known about how newly hired science teachers' practices are enacted throughout a cycle of instruction and how these practices can be influenced by macro-, meso-, and micro-policies. Knowing how policies impact practice can result in better policies or better support for certain policies in order to enhance the instruction of newly hired teachers. This comparative study investigated how 12 newly hired science teachers at sites in South Africa (SA) and the United States (US) progressed through an instructional cycle of planning, teaching, and reflection. The qualitative data were analysed through beginning teacher competency frameworks, the cycle of instruction, and institutional theory. Data analysis revealed prevailing areas of practice and connections to levels of policy within the instructional cycle phases. There were some differences between the SA and US teachers and among first-, second-, and third-year teachers. More importantly, this study indicates that newly hired teachers are susceptible to micro-policies and are progressively developing their practice. It also shows the importance of meso-level connectors. It suggests that teacher educators and policy makers must consider how to prepare and support newly hired science teachers to achieve the shared global visions of science teaching.

Angular Momentum of a Bose-Einstein Condensate in a Synthetic Rotational Field

NASA Astrophysics Data System (ADS)

Qu, Chunlei; Stringari, Sandro

2018-05-01

By applying a position-dependent detuning to a spin-orbit-coupled Hamiltonian with equal Rashba and Dresselhaus coupling, we exploit the behavior of the angular momentum of a harmonically trapped Bose-Einstein condensed atomic gas and discuss the distinctive role of its canonical and spin components. By developing the formalism of spinor hydrodynamics, we predict the precession of the dipole oscillation caused by the synthetic rotational field, in analogy with the precession of the Foucault pendulum, the excitation of the scissors mode, following the sudden switching off of the detuning, and the occurrence of Hall-like effects. When the detuning exceeds a critical value, we observe a transition from a vortex free, rigidly rotating quantum gas to a gas containing vortices with negative circulation which results in a significant reduction of the total angular momentum.

Particle shape effects on the fracture of discontinuously-reinforced 6061-A1 matrix composites

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

Shi, N.; Song, S.G.; Gray, G.T., III

1996-05-01

Effects on fracture and ductility of a spherical and an angular particulate-reinforced 6061-Al composite containing 20(vol)% Al{sub 2}O{sub 3} were studied using SEM fractography and modeled using finite element method (FEM). The spherical particulate composite exhibited a slightly lower yield strength and work hardening rate but a considerably higher ductility than the angular counterpart. SEM fractography showed that during tensile deformation the spherical composite failed through void nucleation and linking in the matrix near the reinforcement/matrix interface, whereas the angular composite failed through particle fracture and matrix ligament rupture. FEM results indicate that the distinction between the failure modes formore » these two composites can be attributed to differences in development of internal stresses and strains within the composites due to particle shape.« less

Hybrid 3-D rocket trajectory program. Part 1: Formulation and analysis. Part 2: Computer programming and user's instruction. [computerized simulation using three dimensional motion analysis

NASA Technical Reports Server (NTRS)

Huang, L. C. P.; Cook, R. A.

1973-01-01

Models utilizing various sub-sets of the six degrees of freedom are used in trajectory simulation. A 3-D model with only linear degrees of freedom is especially attractive, since the coefficients for the angular degrees of freedom are the most difficult to determine and the angular equations are the most time consuming for the computer to evaluate. A computer program is developed that uses three separate subsections to predict trajectories. A launch rail subsection is used until the rocket has left its launcher. The program then switches to a special 3-D section which computes motions in two linear and one angular degrees of freedom. When the rocket trims out, the program switches to the standard, three linear degrees of freedom model.

Measurement of the Energy-Dependent Angular Response of the ARES Detector System and Application to Aerial Imaging

NASA Astrophysics Data System (ADS)

Joshi, Tenzing H. Y.; Quiter, Brian J.; Maltz, Jonathan S.; Bandstra, Mark S.; Haefner, Andrew; Eikmeier, Nicole; Wagner, Eric; Luke, Tanushree; Malchow, Russell; McCall, Karen

2017-07-01

The Airborne Radiological Enhanced-sensor System (ARES) includes a prototype helicopter-borne CsI(Na) detector array that has been developed as part of the DHS Domestic Nuclear Detection Office Advanced Technology Demonstration. The detector system geometry comprises two pairs of 23-detector arrays designed to function as active masks, providing additional angular resolution of measured gamma rays in the roll dimension. Experimental measurements, using five radioisotopes (137Cs, 60Co, 241Am, 131I, and 99mTc), were performed to map the detector response in both roll and pitch dimensions. This paper describes the acquisition and analysis of these characterization measurements, calculation of the angular response of the ARES system, and how this response function is used to improve aerial detection and localization of radiological and nuclear threat sources.

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

Peng, Jun, E-mail: pengjun@cimm.com.cn; Zhang, Li, E-mail: zhangli@cimm.com.cn; School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing

The moment of inertia calibration system is developed by Changcheng Institute of Metrology and Measurement (CIMM). Rotation table - torsional spring system is used to generate angular vibration, and laser vibrometer is used to measure rotational angle and the vibration period. The object to be measured is mounted on the top of the rotation table. The air-bearing system is elaborately manufactured which reduce the friction of the angular movement and increase measurement accuracy. Heterodyne laser interferometer collaborates with column diffraction grating is used in the measurement of angular movement. Experiment shows the method of measuring oscillating angle and period introducedmore » in this paper is stable and the time resolution is high. When the air damping effect can’t be neglected in moment of inertia measurement, the periodic waveform area ratio method is introduced to calculate damping ratio and obtain the moment of inertia.« less

Practices Influenced by Policy? An Exploration of Newly Hired Science Teachers at Sites in South Africa and the United States

ERIC Educational Resources Information Center

Navy, S. L.; Luft, J. A.; Toerien, R.; Hewson, P. W.

2018-01-01

In many parts of the world, newly hired science teachers' practices are developing in a complex policy environment. However, little is known about how newly hired science teachers' practices are enacted throughout a cycle of instruction and how these practices can be influenced by macro-, meso-, and micro-policies. Knowing how policies impact…

Sensor Data Quality and Angular Rate Down-Selection Algorithms on SLS EM-1

NASA Technical Reports Server (NTRS)

Park, Thomas; Smith, Austin; Oliver, T. Emerson

2018-01-01

The NASA Space Launch System Block 1 launch vehicle is equipped with an Inertial Navigation System (INS) and multiple Rate Gyro Assemblies (RGA) that are used in the Guidance, Navigation, and Control (GN&C) algorithms. The INS provides the inertial position, velocity, and attitude of the vehicle along with both angular rate and specific force measurements. Additionally, multiple sets of co-located rate gyros supply angular rate data. The collection of angular rate data, taken along the launch vehicle, is used to separate out vehicle motion from flexible body dynamics. Since the system architecture uses redundant sensors, the capability was developed to evaluate the health (or validity) of the independent measurements. A suite of Sensor Data Quality (SDQ) algorithms is responsible for assessing the angular rate data from the redundant sensors. When failures are detected, SDQ will take the appropriate action and disqualify or remove faulted sensors from forward processing. Additionally, the SDQ algorithms contain logic for down-selecting the angular rate data used by the GNC software from the set of healthy measurements. This paper explores the trades and analyses that were performed in selecting a set of robust fault-detection algorithms included in the GN&C flight software. These trades included both an assessment of hardware-provided health and status data as well as an evaluation of different algorithms based on time-to-detection, type of failures detected, and probability of detecting false positives. We then provide an overview of the algorithms used for both fault-detection and measurement down selection. We next discuss the role of trajectory design, flexible-body models, and vehicle response to off-nominal conditions in setting the detection thresholds. Lastly, we present lessons learned from software integration and hardware-in-the-loop testing.

Linear and angular control of circular walking in healthy older adults and subjects with cerebellar ataxia.

PubMed

Goodworth, Adam D; Paquette, Caroline; Jones, Geoffrey Melvill; Block, Edward W; Fletcher, William A; Hu, Bin; Horak, Fay B

2012-05-01

Linear and angular control of trunk and leg motion during curvilinear navigation was investigated in subjects with cerebellar ataxia and age-matched control subjects. Subjects walked with eyes open around a 1.2-m circle. The relationship of linear to angular motion was quantified by determining the ratios of trunk linear velocity to trunk angular velocity and foot linear position to foot angular position. Errors in walking radius (the ratio of linear to angular motion) also were quantified continuously during the circular walk. Relative variability of linear and angular measures was compared using coefficients of variation (CoV). Patterns of variability were compared using power spectral analysis for the trunk and auto-covariance analysis for the feet. Errors in radius were significantly increased in patients with cerebellar damage as compared to controls. Cerebellar subjects had significantly larger CoV of feet and trunk in angular, but not linear, motion. Control subjects also showed larger CoV in angular compared to linear motion of the feet and trunk. Angular and linear components of stepping differed in that angular, but not linear, foot placement had a negative correlation from one stride to the next. Thus, walking in a circle was associated with more, and a different type of, variability in angular compared to linear motion. Results are consistent with increased difficulty of, and role of the cerebellum in, control of angular trunk and foot motion for curvilinear locomotion.

First high-statistics and high-resolution recoil-ion data from the WITCH retardation spectrometer

NASA Astrophysics Data System (ADS)

Finlay, P.; Breitenfeldt, M.; Porobić, T.; Wursten, E.; Ban, G.; Beck, M.; Couratin, C.; Fabian, X.; Fléchard, X.; Friedag, P.; Glück, F.; Herlert, A.; Knecht, A.; Kozlov, V. Y.; Liénard, E.; Soti, G.; Tandecki, M.; Traykov, E.; Van Gorp, S.; Weinheimer, Ch.; Zákoucký, D.; Severijns, N.

2016-07-01

The first high-statistics and high-resolution data set for the integrated recoil-ion energy spectrum following the β^+ decay of 35Ar has been collected with the WITCH retardation spectrometer located at CERN-ISOLDE. Over 25 million recoil-ion events were recorded on a large-area multichannel plate (MCP) detector with a time-stamp precision of 2ns and position resolution of 0.1mm due to the newly upgraded data acquisition based on the LPC Caen FASTER protocol. The number of recoil ions was measured for more than 15 different settings of the retardation potential, complemented by dedicated background and half-life measurements. Previously unidentified systematic effects, including an energy-dependent efficiency of the main MCP and a radiation-induced time-dependent background, have been identified and incorporated into the analysis. However, further understanding and treatment of the radiation-induced background requires additional dedicated measurements and remains the current limiting factor in extracting a beta-neutrino angular correlation coefficient for 35Ar decay using the WITCH spectrometer.

The neural correlates of semantic richness: evidence from an fMRI study of word learning.

PubMed

Ferreira, Roberto A; Göbel, Silke M; Hymers, Mark; Ellis, Andrew W

2015-04-01

We investigated the neural correlates of concrete nouns with either many or few semantic features. A group of 21 participants underwent two days of training and were then asked to categorize 40 newly learned words and a set of matched familiar words as living or nonliving in an MRI scanner. Our results showed that the most reliable effects of semantic richness were located in the left angular gyrus (AG) and middle temporal gyrus (MTG), where activation was higher for semantically rich than poor words. Other areas showing the same pattern included bilateral precuneus and posterior cingulate gyrus. Our findings support the view that AG and anterior MTG, as part of the multimodal network, play a significant role in representing and integrating semantic features from different input modalities. We propose that activation in bilateral precuneus and posterior cingulate gyrus reflects interplay between AG and episodic memory systems during semantic retrieval. Copyright © 2015 Elsevier Inc. All rights reserved.

Tidal Interaction among Red Giants Close Binary Systems in APOGEE Database

NASA Astrophysics Data System (ADS)

Sun, Meng; Arras, Phil; Majewski, Steven R.; Troup, Nicholas William; Weinberg, Nevin N.

2017-01-01

Motivated by the newly discovered close binary systems in the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1), the tidal evolution of binaries containing a red giant branch (RGB) star with a stellar or substellar companion was investigated. The tide raised by the companion in the RGB star leads to exchange of angular momentum between the orbit and the stellar spin, causing the orbit to contract. The tidal dissipation rate is computed using turbulent viscosity acting on the equilibrium tidal flow, where careful attention is paid to the effects of reduced viscosity for close-in companions. Evolutionary models for the RGB stars, from the zero-age main sequence to the present, were acquired from the MESA code. "Standard" turbulent viscosity gives rise to such a large orbital decay that many observed systems have decay times much shorter than the RGB evolution time. Several theories for "reduced" turbulent viscosity are investigated, and reduce the number of systems with uncomfortably short decay times.

Spin-dependent post-Newtonian parameters from EMRI computation in Kerr background

NASA Astrophysics Data System (ADS)

Friedman, John; Le Tiec, Alexandre; Shah, Abhay

2013-04-01

Because the extreme mass-ratio inspiral (EMRI) approximation is accurate to all orders in v/c, it can be used to find high order post-Newtonian parameters that are not yet analytically accessible. We report here on progress in computing spin-dependent, conservative, post-Newtonian parameters from a radiation-gauge computation for a particle in circular orbit in a family of Kerr geometries. For a particle with 4-velocity u^α= U k^α, with k^α the helical Killing vector of the perturbed spacetime, the renormalized perturbation δU, when written as a function of the particle's angular velocity, is invariant under gauge transformations generated by helically symmetric vectors. The EMRI computations are done in a modified radiation gauge. Extracted parameters are compared to previously known and newly computed spin-dependent post-Newtonian terms. This work is modeled on earlier computations by Blanchet, Detweiler, Le Tiec and Whiting of spin-independent terms for a particle in circular orbit in a Schwarzschild geometry.

[Pathomorphology of regenerative processes in mandibular fracture after sodium succinate treatment and laser magnetotherapy in an experimental setting].

PubMed

Faustov, L A; Nedel'ko, N A; Morozova, M V

2001-01-01

Morphological reactions in tissue adjacent to mandibular angular fracture were studied in guinea pigs treated with sodium succinate and laser magnetotherapy. Due to succinate therapy the exudative component of inflammation was less expressed in comparison with the control, macrophagal reaction and neoangiogenesis were activated, the volume of damaged muscle tissue and the incidence of suppurations decreased. The number of osteoblasts increased and new bone structures acquired a lamellar pattern earlier than in the control. Sodium succinate therapy in combination with laser magnetotherapy had a more pronounced positive effect as regards activation of macrophagal reaction and neoangiogenesis and a decrease in the area of fibrosclerotic changes in the zone of damaged muscles, where newly formed myosymplasts differentiated into myotubes and even in muscle fibers. Suppuration of the wound was prevented. Bone tissue in the fracture zone formed without preliminary formation of cartilaginous tissue, which resulted in more rapid osteogenesis (lamellar bone growth in the fracture zone).

REM sleep selectively prunes and maintains new synapses in development and learning.

PubMed

Li, Wei; Ma, Lei; Yang, Guang; Gan, Wen-Biao

2017-03-01

The functions and underlying mechanisms of rapid eye movement (REM) sleep remain unclear. Here we show that REM sleep prunes newly formed postsynaptic dendritic spines of layer 5 pyramidal neurons in the mouse motor cortex during development and motor learning. This REM sleep-dependent elimination of new spines facilitates subsequent spine formation during development and when a new motor task is learned, indicating a role for REM sleep in pruning to balance the number of new spines formed over time. Moreover, REM sleep also strengthens and maintains newly formed spines, which are critical for neuronal circuit development and behavioral improvement after learning. We further show that dendritic calcium spikes arising during REM sleep are important for pruning and strengthening new spines. Together, these findings indicate that REM sleep has multifaceted functions in brain development, learning and memory consolidation by selectively eliminating and maintaining newly formed synapses via dendritic calcium spike-dependent mechanisms.

Occupant Motion Sensors : Development and Testing of Piezoresistive Mouthpiece Rotational Accelerometer

DOT National Transportation Integrated Search

1973-07-01

A miniature piezoresistive mouthpiece rotational accelerometer has been developed to measure the angular acceleration of a head during a simulated vehicle crash. Corrections have been electronically applied to the rotational accelerometer to reduce i...

Evaluation system for minor nervous dysfunction by pronation and supination of forearm using wireless acceleration and angular velocity sensors.

PubMed

Iramina, Keiji; Kamei, Yuuichiro; Katayama, Yoshinori

2011-01-01

We developed a simple, portable and easy system to the motion of pronation and supination of the forearm. This motion was measured by wireless acceleration and angular velocity sensor. The aim of this system is evaluation of minor nervous dysfunction. It is for the screening of the developmental disorder child. In this study, in order to confirm the effectiveness of this system, the reference curve of the neuromotor development was experimentally obtained. We studied 212 participants (108 males, 104 females) aged 7 to 12 years attending the kindergarten school. We could obtain the reference curve of the neuromotor development using this system. We also investigated the difference of neuromotor function between normally developed children and a ADHD child. There is a possibility that abnormality of the minor nervous dysfunction can be detected by using this system.

Measurement Technology

NASA Technical Reports Server (NTRS)

1972-01-01

New and improved materials, equipment, and techniques in measurement technology, developed by the aerospace industry, are presented for economic development in other industries. The developments are grouped as follows: (1) surface measurement, (2) alignment and orientation of bodies, (3) fluid measurement, (4) linear and angular measurements, and (5) force measurements.

TU-F-CAMPUS-I-04: A Novel Phantom to Evaluate Longitudinal and Angular Automatic Tube Current Modulation (ATCM) in CT

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

Merzan, D; Bujila, R; Nowik, P

Purpose: To manufacture a phantom specifically designed for the purpose of evaluating the performance of the longitudinal and angular automatic tube current modulation (ATCM) on modern CT scanners. Methods: In order to evaluate angular ATCM, the phantom has an elliptical cross section (aspect ratio 3:2). To evaluate longitudinal ATCM, the phantom consists of 3 sections, with different major axes (25 cm, 30 cm and 35 cm). Each section is 15 cm long in the longitudinal direction. Between each section is a smooth transition. The phantom was milled from a solid block of PMMA. ATCM performance is evaluated by 1) analyzingmore » the applied tube current for each slice of the phantom and 2) analyzing the distribution of image noise (σ) along the scan direction at different positions in the phantom. A demonstration of the ATCM performance evaluation is given by investigating the effects of miscentering during a CT scan. Results: The developed phantom has proven useful for evaluating both the longitudinal and angular ATCM on modern CT scanners (spiral collimations ≥ 4 cm). Further benefits are the smooth transitions between the sections that prevent abnormal responses in the ATCM and the invariant sections that provide a means for investigating the stability of image noise. The homogeneity of the phantom makes image noise at different positions along the scan direction easy to quantify, which is crucial to understand how well the applied ATCM can produce a desired image quality. Conclusion: It is important to understand how the ATCM functions on CT scanners as it can directly affect dose and image quality. The phantom that has been developed is a most valuable tool to understand how different variables during a scan can affect the outcome of the longitudinal and angular ATCM.« less

Design and analysis of a spectro-angular surface plasmon resonance biosensor operating in the visible spectrum

NASA Astrophysics Data System (ADS)

Filion-Côté, Sandrine; Roche, Philip J. R.; Foudeh, Amir M.; Tabrizian, Maryam; Kirk, Andrew G.

2014-09-01

Surface plasmon resonance (SPR) sensing is one of the most widely used methods to implement biosensing due to its sensitivity and capacity for label-free detection. Whilst most commercial SPR sensors operate in the angular regime, it has recently been shown that an increase in sensitivity and a greater robustness against noise can be achieved by measuring the reflectivity when varying both the angle and wavelength simultaneously, in a so-called spectro-angular SPR biosensor. A single value decomposition method is used to project the two-dimensional spectro-angular reflection signal onto a basis set and allow the image obtained from an unknown refractive index sample to be compared very accurately with a pre-calculated reference set. Herein we demonstrate that a previously reported system operated in the near infra-red has a lower detection limit when operating in the visible spectrum due to the improved spatial resolution and numerical precision of the image sensor. The SPR biosensor presented here has an experimental detection limit of 9.8 × 10-7 refractive index unit. To validate the system as a biosensor, we also performed the detection of synthetic RNA from pathogenic Legionella pneumophila with the developed biosensing platform.

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.

Maximum voluntary joint torque as a function of joint angle and angular velocity: model development and application to the lower limb.

PubMed

Anderson, Dennis E; Madigan, Michael L; Nussbaum, Maury A

2007-01-01

Measurements of human strength can be important during analyses of physical activities. Such measurements have often taken the form of the maximum voluntary torque at a single joint angle and angular velocity. However, the available strength varies substantially with joint position and velocity. When examining dynamic activities, strength measurements should account for these variations. A model is presented of maximum voluntary joint torque as a function of joint angle and angular velocity. The model is based on well-known physiological relationships between muscle force and length and between muscle force and velocity and was tested by fitting it to maximum voluntary joint torque data from six different exertions in the lower limb. Isometric, concentric and eccentric maximum voluntary contractions were collected during hip extension, hip flexion, knee extension, knee flexion, ankle plantar flexion and dorsiflexion. Model parameters are reported for each of these exertion directions by gender and age group. This model provides an efficient method by which strength variations with joint angle and angular velocity may be incorporated into comparisons between joint torques calculated by inverse dynamics and the maximum available joint torques.

Catching a Rolling Stone: Dynamics and Control of a Spacecraft and an Asteroid

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.; Shen, Haijun; Jesick, Mark C; Cornelius, David M

2013-01-01

In a recent report, a robotic spacecraft mission is proposed for the purpose of collecting a small asteroid, or a small part of a large one, and transporting it to an orbit in the Earth-Moon system. Such an undertaking will require solutions to many of the engineering problems associated with deflection of an asteroid that poses a danger to Earth. In both cases, it may be necessary for a spacecraft to approach an asteroid from a nearby position, hover for some amount of time, move with the same angular velocity as the asteroid, descend, perhaps ascend, and finally arrest the angular velocity of the asteroid. Dynamics and control in each of these activities is analyzed in order to determine the velocity increments and control torque that must be provided by a reaction control system, and the mass of the propellant that will be consumed. Two attitude control algorithms are developed, one to deal with synchronizing the spacecraft s angular velocity with that of the asteroid, and the other to arrest the asteroid s angular velocity. A novel approach is proposed for saving fuel in the latter case.

Dual actuation micro-mirrors

NASA Astrophysics Data System (ADS)

Alneamy, A. M.; Khater, M. E.; Al-Ghamdi, M. S.; Park, S.; Heppler, G. R.; Abdel-Rahman, E. M.

2018-07-01

This paper investigates the performance of cantilever-type micro-mirrors under electromagnetic, electrostatic and dual actuation. We developed and validated a two-DOFs model of the coupled bending-torsion motions of the mirror and used it in conjunction with experiments in air and in vacuum to compare all three actuation methods. We found that electromagnetic actuation is the most effective delivering a scanning range of  ± out of a geometrically allowable range of  ± at a current amplitude i  =  3 mA and a magnetic field of B  =  30 mT. Electrostatic actuation, whether alone or in conjunction with electromagnetic actuation, limited the stable angular range to smaller values (as small as ) due to the presence of spurious piston motions. This is an innate characteristic of micro-scale electrostatic actuation, the electrostatic force and the undesirable piston motion grow faster than the electrostatic torque and the desired angular displacement as the voltage is increased and they limit the stable angular range. Finally, we found that the dual actuation can be used to design two-DOF mirrors where electromagnetic actuation drives angular motion for optical beam steering and electrostatic actuation drives piston motion to control the mirror focus.

The Angular Power Spectrum of BATSE 3B Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Tegmark, Max; Hartmann, Dieter H.; Briggs, Michael S.; Meegan, Charles A.

1996-01-01

We compute the angular power spectrum C(sub l) from the BATSE 3B catalog of 1122 gamma-ray bursts and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales (which probe source clustering and burst repetition) to the largest scales (which constrain possible anisotropics from the Galactic halo or from nearby cosmological large-scale structures). We develop an analysis technique that takes the angular position errors into account. For specific clustering or repetition models, strong upper limits can be obtained down to scales l approx. equal to 30, corresponding to a couple of degrees on the sky. The minimum-variance burst weighting that we employ is visualized graphically as an all-sky map in which each burst is smeared out by an amount corresponding to its position uncertainty. We also present separate bandpass-filtered sky maps for the quadrupole term and for the multipole ranges l = 3-10 and l = 11-30, so that the fluctuations on different angular scales can be inspected separately for visual features such as localized 'hot spots' or structures aligned with the Galactic plane. These filtered maps reveal no apparent deviations from isotropy.

Spectral and angular distribution of photons via radiative damping in extreme ultra-intense laser-plasma interaction

NASA Astrophysics Data System (ADS)

Pandit, Rishi; Sentoku, Yasuhiko

2012-10-01

Spectral and angular distribution of photons produced in the interaction of extremely intense laser (> 10^22,/cm^2) with dense plasma are studied with a help of a collisional particle-in-cell simulation, PICLS. In ultra-intense laser-plasma interaction, electrons are accelerated by the strong laser fields and emit γ-ray photons mainly via two processes, namely, Bremsstrahlung and radiative damping. We had developed numerical models of these processes in PICLS and study the spectrum and the angular distribution of γ-rays produced in the relativistic laser regime. Such relativistic γ-rays have wide range of frequencies and the angular distribution depends on the hot electron source. From the power loss calculation in PICLS we found that the Bremsstrahlung will get saturated at I > 10^22,/cm^2 while the radiative damping will continuously increase. Comparing the details of γ-rays from the Bremsstrahlung and the radiative damping in simulations, we will discuss the laser parameters and the target conditions (geometry and material) to distinguish the photons from each process and how to catch the signature of the radiative damping in future experiments.

Ground simulation of wide frequency band angular vibration for Lander's optic sensors

NASA Astrophysics Data System (ADS)

Xing, Zhigang; Xiang, Jianwei; Zheng, Gangtie

2017-11-01

To guide a lander of Moon or Mars exploration spacecraft during the stage of descent onto a desired place, optic sensors have been chosen to take the task, which include optic cameras and laser distance meters. However, such optic sensors are sensitive to vibrations, especially angular vibrations, from the lander. To reduce the risk of abnormal function and ensure the performance of optic sensors, ground simulations are necessary. More importantly, the simulations can be used as a method for examining the sensor performance and finding possible improvement on the sensor design. In the present paper, we proposed an angular vibration simulation method during the landing. This simulation method has been realized into product and applied to optic sensor tests for the moon lander. This simulator can generate random angular vibration in a frequency range from 0 to 2000Hz, the control precision is +/-1dB, and the linear translational speed can be set to the required descent speed. The operation and data processing methods of this developed simulator are the same as a normal shake table. The analysis and design methods are studied in the present paper, and test results are also provided.

Radio Pumping of Ionospheric Plasma with Orbital Angular Momentum

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

Leyser, T. B.; Norin, L.; McCarrick, M.

2009-02-13

Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE.

Radio pumping of ionospheric plasma with orbital angular momentum.

PubMed

Leyser, T B; Norin, L; McCarrick, M; Pedersen, T R; Gustavsson, B

2009-02-13

Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE.

Runway Exit Designs for Capacity Improvement Demonstrations. Phase 1. Algorithm Development

DTIC Science & Technology

1990-06-01

Dynamic Module 39 Table 3.1 Aircraft Approach Category Classification (FAA, 1988). Category Landing Speed (1.3 Vst ,,,) A less than 91 Knots B From 91 to...inertia about the vertical axis, in Kg-m-m, a is the angular acceleration (rad/sec,) of the aircraft fuselage as it executes the turning maneuver, wb is the...breakdown of the angular acceleration yields for Eq. 3.13 the following, I/ (V R 2 / g"= m g wb Im/100 (1- Im100) (3.16) where, R represents the rate of

The Future of X-Ray Optics

NASA Technical Reports Server (NTRS)

Weisskopf, Martin C.

2013-01-01

The most important next step is the development of X-ray optics comparable to (or better than) Chandra in angular resolution that far exceed Chandra s effective area. Use the long delay to establish an adequately funded, competitive technology program along the lines I have recommended. Don't be diverted from this objective, except for Explorer-class missions. Progress in X-ray optics, with emphasis on the angular resolution, is central to the paradigm-shifting discoveries and the contributions of X-ray astronomy to multiwavelength astrophysics over the past 51 years.

Theoretical proposal for determining angular momentum compensation in ferrimagnets

NASA Astrophysics Data System (ADS)

Zhu, Zhifeng; Fong, Xuanyao; Liang, Gengchiau

2018-05-01

This work demonstrates that the magnetization and angular momentum compensation temperatures (TMC and TAMC) in ferrimagnets can be unambiguously determined by performing two sets of temperature-dependent current switching, with the symmetry reversals at TMC and TAMC, respectively. A theoretical model based on the modified Landau-Lifshitz-Bloch equation is developed to systematically study the spin torque effect under different temperatures, and numerical simulations are performed to corroborate our proposal. Furthermore, we demonstrate that the recently reported linear relation between TAMC and TMC can be explained using the Curie-Weiss theory.

On the quantum-channel capacity for orbital angular momentum-based free-space optical communications.

PubMed

Zhang, Yequn; Djordjevic, Ivan B; Gao, Xin

2012-08-01

Inspired by recent demonstrations of orbital angular momentum-(OAM)-based single-photon communications, we propose two quantum-channel models: (i) the multidimensional quantum-key distribution model and (ii) the quantum teleportation model. Both models employ operator-sum representation for Kraus operators derived from OAM eigenkets transition probabilities. These models are highly important for future development of quantum-error correction schemes to extend the transmission distance and improve date rates of OAM quantum communications. By using these models, we calculate corresponding quantum-channel capacities in the presence of atmospheric turbulence.

Binary neutron stars with arbitrary spins in numerical relativity

NASA Astrophysics Data System (ADS)

Tacik, Nick; Foucart, Francois; Pfeiffer, Harald P.; Haas, Roland; Ossokine, Serguei; Kaplan, Jeff; Muhlberger, Curran; Duez, Matt D.; Kidder, Lawrence E.; Scheel, Mark A.; Szilágyi, Béla

2015-12-01

We present a code to construct initial data for binary neutron star systems in which the stars are rotating. Our code, based on a formalism developed by Tichy, allows for arbitrary rotation axes of the neutron stars and is able to achieve rotation rates near rotational breakup. We compute the neutron star angular momentum through quasilocal angular momentum integrals. When constructing irrotational binary neutron stars, we find a very small residual dimensionless spin of ˜2 ×10-4 . Evolutions of rotating neutron star binaries show that the magnitude of the stars' angular momentum is conserved, and that the spin and orbit precession of the stars is well described by post-Newtonian approximation. We demonstrate that orbital eccentricity of the binary neutron stars can be controlled to ˜0.1 % . The neutron stars show quasinormal mode oscillations at an amplitude which increases with the rotation rate of the stars.

Observation of orbital order in the half-filled 4 f Gd compound

DOE PAGES

Jang, H.; Kang, B. Y.; Cho, B. K.; ...

2016-11-18

Half-filled electron systems, even with the maximized spin angular moment, have been given little attention because of their zero-orbital angular moment according to Hund’s rule. Nevertheless, there are several measurements that show evidence of a nonzero orbital moment as well as spin-orbit coupling. Here we report for the first time the orbital order in a half-filled 4f-electron system GdB 4, using the resonant soft x-ray scattering at Gd M 4,5-edges. Furthermore, we discovered that the development of this orbital order is strongly coupled with the antiferromagnetic spin order. Lastly, these results clearly demonstrate that even in half-filled electron systems themore » orbital angular moment can be an important parameter to describe material properties, and may provide significant opportunities for tailoring new correlated electron systems.« less

Directional view interpolation for compensation of sparse angular sampling in cone-beam CT.

PubMed

Bertram, Matthias; Wiegert, Jens; Schafer, Dirk; Aach, Til; Rose, Georg

2009-07-01

In flat detector cone-beam computed tomography and related applications, sparse angular sampling frequently leads to characteristic streak artifacts. To overcome this problem, it has been suggested to generate additional views by means of interpolation. The practicality of this approach is investigated in combination with a dedicated method for angular interpolation of 3-D sinogram data. For this purpose, a novel dedicated shape-driven directional interpolation algorithm based on a structure tensor approach is developed. Quantitative evaluation shows that this method clearly outperforms conventional scene-based interpolation schemes. Furthermore, the image quality trade-offs associated with the use of interpolated intermediate views are systematically evaluated for simulated and clinical cone-beam computed tomography data sets of the human head. It is found that utilization of directionally interpolated views significantly reduces streak artifacts and noise, at the expense of small introduced image blur.

Observation of orbital order in the half-filled 4 f Gd compound

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

Jang, H.; Kang, B. Y.; Cho, B. K.

Half-filled electron systems, even with the maximized spin angular moment, have been given little attention because of their zero-orbital angular moment according to Hund’s rule. Nevertheless, there are several measurements that show evidence of a nonzero orbital moment as well as spin-orbit coupling. Here we report for the first time the orbital order in a half-filled 4f-electron system GdB 4, using the resonant soft x-ray scattering at Gd M 4,5-edges. Furthermore, we discovered that the development of this orbital order is strongly coupled with the antiferromagnetic spin order. Lastly, these results clearly demonstrate that even in half-filled electron systems themore » orbital angular moment can be an important parameter to describe material properties, and may provide significant opportunities for tailoring new correlated electron systems.« less

Experiments in Aligning Threaded Parts Using a Robot Hand

NASA Technical Reports Server (NTRS)

Diftler, M. A.; Walker, I. D.

1999-01-01

Techniques for determining and correcting threaded part alignment using force and angular position data are developed to augment currently limited techniques for align- ing threaded parts. These new techniques are based on backspinning a nut with respect to a bolt and measuring the force change that occurs when the bolt "falls" into the nut. Kinematic models that describe the relationship between threaded parts during backspinning are introduced and are used to show how angular alignment may be determined. The models indicate how to distinguish between the aligned and misaligned cases of a bolt and a nut connection by using axial force data only. In addition, by tracking the in-plane relative attitude of the bolt during spinning, data can be obtained on the direction of the angular misalignment which, in turn, is used to correct the misalignment. Results from experiments using a bolt held in a specialized fixture and a three fingers Stanford/JPL hand are presented.

Angular Deformities of the Lower Limb in Children

PubMed Central

Espandar, Ramin; Mortazavi, Seyed Mohammad-Javad; Baghdadi, Taghi

2010-01-01

Angular deformities of the lower limbs are common during childhood. In most cases this represents a variation in the normal growth pattern and is an entirely benign condition. Presence of symmetrical deformities and absence of symptoms, joint stiffness, systemic disorders or syndromes indicates a benign condition with excellent long-term outcome. In contrast, deformities which are asymmetrical and associated with pain, joint stiffness, systemic disorders or syndromes may indicate a serious underlying cause and require treatment. Little is known about the relationship between sport participation and body adaptations during growth. Intense soccer participation increases the degree of genu varum in males from the age of 16. Since, according to some investigations, genu varum predisposes individuals to more injuries, efforts to reduce the development of genu varum in soccer players are warranted. In this article major topics of angular deformities of the knees in pediatric population are practically reviewed. PMID:22375192

Angular distributions of plasma edge velocity and integrated intensity: Update on specific impulse for Ablative Laser Propulsion

NASA Astrophysics Data System (ADS)

Lin, Jun; Pakhomov, Andrew V.

2005-04-01

This work concludes our discussion of the image processing technique developed earlier for determination of specific impulse (Isp) for Ablative Laser Propulsion (ALP). The plasma plumes are recorded with a time-resolved intensified charge-coupled device (ICCD) camera. The plasma was formed in vacuum (˜ 3×10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ˜35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb elements. Angular profiles for integrated intensity and plasma expansion velocity were determined for the tested elements. Such profiles were used further for assessment of specific impulse. Specific impulses derived from angular distributions of plasma expansion velocity and integral intensity appeared in excellent agreement with the data derived earlier from force measurements.

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

Scheinker, Alexander

Here, we study control of the angular-velocity actuated nonholonomic unicycle, via a simple, bounded extremum seeking controller which is robust to external disturbances and measurement noise. The vehicle performs source seeking despite not having any position information about itself or the source, able only to sense a noise corrupted scalar value whose extremum coincides with the unknown source location. In order to control the angular velocity, rather than the angular heading directly, a controller is developed such that the closed loop system exhibits multiple time scales and requires an analysis approach expanding the previous work of Kurzweil, Jarnik, Sussmann, andmore » Liu, utilizing weak limits. We provide analytic proof of stability and demonstrate how this simple scheme can be extended to include position-independent source seeking, tracking, and collision avoidance of groups on autonomous vehicles in GPS-denied environments, based only on a measure of distance to an obstacle, which is an especially important feature for an autonomous agent.« less

Angular description for 3D scattering centers

NASA Astrophysics Data System (ADS)

Bhalla, Rajan; Raynal, Ann Marie; Ling, Hao; Moore, John; Velten, Vincent J.

2006-05-01

The electromagnetic scattered field from an electrically large target can often be well modeled as if it is emanating from a discrete set of scattering centers (see Fig. 1). In the scattering center extraction tool we developed previously based on the shooting and bouncing ray technique, no correspondence is maintained amongst the 3D scattering center extracted at adjacent angles. In this paper we present a multi-dimensional clustering algorithm to track the angular and spatial behaviors of 3D scattering centers and group them into features. The extracted features for the Slicy and backhoe targets are presented. We also describe two metrics for measuring the angular persistence and spatial mobility of the 3D scattering centers that make up these features in order to gather insights into target physics and feature stability. We find that features that are most persistent are also the most mobile and discuss implications for optimal SAR imaging.

A Pearson VII distribution function for fast calculation of dechanneling and angular dispersion of beams

NASA Astrophysics Data System (ADS)

Shao, Lin; Peng, Luohan

2009-12-01

Although multiple scattering theories have been well developed, numerical calculation is complicated and only tabulated values have been available, which has caused inconvenience in practical use. We have found that a Pearson VII distribution function can be used to fit Lugujjo and Mayer's probability curves in describing the dechanneling phenomenon in backscattering analysis, over a wide range of disorder levels. Differentiation of the obtained function gives another function to calculate angular dispersion of the beam in the frameworks by Sigmund and Winterbon. The present work provides an easy calculation of both dechanneling probability and angular dispersion for any arbitrary combination of beam and target having a reduced thickness ⩾0.6, which can be implemented in modeling of channeling spectra. Furthermore, we used a Monte Carlo simulation program to calculate the deflection probability and compared them with previously tabulated data. A good agreement was reached.

A Homing Missile Control System to Reduce the Effects of Radome Diffraction

NASA Technical Reports Server (NTRS)

Smith, Gerald L.

1960-01-01

The problem of radome diffraction in radar-controlled homing missiles at high speeds and high altitudes is considered from the point of view of developing a control system configuration which will alleviate the deleterious effects of the diffraction. It is shown that radome diffraction is in essence a kinematic feedback of body angular velocities which causes the radar to sense large apparent line-of-sight angular velocities. The normal control system cannot distinguish between the erroneous and actual line-of-sight rates, and entirely wrong maneuvers are produced which result in large miss distances. The problem is resolved by adding to the control system a special-purpose computer which utilizes measured body angular velocity to extract from the radar output true line-of-sight information for use in steering the missile. The computer operates on the principle of sampling and storing the radar output at instants when the body angular velocity is low and using this stored information for maneuvering commands. In addition, when the angular velocity is not low the computer determines a radome diffraction compensation which is subtracted from the radar output to reduce the error in the sampled information. Analog simulation results for the proposed control system operating in a coplanar (vertical plane) attack indicate a potential decrease in miss distance to an order of magnitude below that for a conventional system. Effects of glint noise, random target maneuvers, initial heading errors, and missile maneuverability are considered in the investigation.

Protoplanetary disc response to distant tidal encounters in stellar clusters

NASA Astrophysics Data System (ADS)

Winter, A. J.; Clarke, C. J.; Rosotti, G.; Booth, R. A.

2018-04-01

The majority of stars form in a clustered environment. This has an impact on the evolution of surrounding protoplanetary discs (PPDs) due to either photoevaporation or tidal truncation. Consequently, the development of planets depends on formation environment. Here, we present the first thorough investigation of tidally induced angular momentum loss in PPDs in the distant regime, partly motivated by claims in the literature for the importance of distant encounters in disc evolution. We employ both theoretical predictions and dynamical/hydrodynamical simulations in 2D and 3D. Our theoretical analysis is based on that of Ostriker (1994) and leads us to conclude that in the limit that the closest approach distance xmin ≫ r, the radius of a particle ring, the fractional change in angular momentum scales as (xmin/r)-5. This asymptotic limit ensures that the cumulative effect of distant encounters is minor in terms of its influence on disc evolution. The angular momentum transfer is dominated by the m = 2 Lindblad resonance for closer encounters and by the m = 1, ω = 0 Lindblad resonance at large xmin/r. We contextualize these results by comparing expected angular momentum loss for the outer edge of a PPD due to distant and close encounters. Contrary to the suggestions of previous works, we do not find that distant encounters contribute significantly to angular momentum loss in PPDs. We define an upper limit for closest approach distance where interactions are significant as a function of arbitrary host to perturber mass ratio M2/M1.

Angular momentum transport by heat-driven g-modes in slowly pulsating B stars

NASA Astrophysics Data System (ADS)

Townsend, R. H. D.; Goldstein, J.; Zweibel, E. G.

2018-03-01

Motivated by recent interest in the phenomenon of waves transport in massive stars, we examine whether the heat-driven gravity (g) modes excited in slowly pulsating B (SPB) stars can significantly modify the stars' internal rotation. We develop a formalism for the differential torque exerted by g modes, and implement this formalism using the GYRE oscillation code and the MESASTAR stellar evolution code. Focusing first on a 4.21M⊙ model, we simulate 1 000 yr of stellar evolution under the combined effects of the torque due to a single unstable prograde g mode (with an amplitude chosen on the basis of observational constraints), and diffusive angular momentum transport due to convection, overshooting, and rotational instabilities. We find that the g mode rapidly extracts angular momentum from the surface layers, depositing it deeper in the stellar interior. The angular momentum transport is so efficient that by the end of the simulation, the initially non-rotating surface layers are spun in the retrograde direction to ≈ 30 per cent of the critical rate. However, the additional inclusion of magnetic stresses in our simulations almost completely inhibits this spin-up. Expanding our simulations to cover the whole instability strip, we show that the same general behaviour is seen in all SPB stars. After providing some caveats to contextualize our results, we hypothesize that the observed slower surface rotation of SPB stars (as compared to other B-type stars) may be the direct consequence of the angular momentum transport that our simulations demonstrate.

Whole-body angular momentum during stair ascent and descent.

PubMed

Silverman, Anne K; Neptune, Richard R; Sinitski, Emily H; Wilken, Jason M

2014-04-01

The generation of whole-body angular momentum is essential in many locomotor tasks and must be regulated in order to maintain dynamic balance. However, angular momentum has not been investigated during stair walking, which is an activity that presents a biomechanical challenge for balance-impaired populations. We investigated three-dimensional whole-body angular momentum during stair ascent and descent and compared it to level walking. Three-dimensional body-segment kinematic and ground reaction force (GRF) data were collected from 30 healthy subjects. Angular momentum was calculated using a 13-segment whole-body model. GRFs, external moment arms and net joint moments were used to interpret the angular momentum results. The range of frontal plane angular momentum was greater for stair ascent relative to level walking. In the transverse and sagittal planes, the range of angular momentum was smaller in stair ascent and descent relative to level walking. Significant differences were also found in the ground reaction forces, external moment arms and net joint moments. The sagittal plane angular momentum results suggest that individuals alter angular momentum to effectively counteract potential trips during stair ascent, and reduce the range of angular momentum to avoid falling forward during stair descent. Further, significant differences in joint moments suggest potential neuromuscular mechanisms that account for the differences in angular momentum between walking conditions. These results provide a baseline for comparison to impaired populations that have difficulty maintaining dynamic balance, particularly during stair ascent and descent. Copyright © 2014 Elsevier B.V. All rights reserved.

6 CFR 7.26 - Derivative classification.

Code of Federal Regulations, 2011 CFR

2011-01-01

... already classified, and marking the newly developed material consistent with the classification markings... classification decisions and carry forward to any newly created documents the pertinent classification markings. (d) Information classified derivatively from other classified information shall be classified and...

Occupant Motion Sensors : Rotational Accelerometer Development

DOT National Transportation Integrated Search

1972-04-01

A miniature mouthpiece rotational accelerometer has been developed to measure the angular acceleration of a head during vehicle crash or impact conditions. The device has been tested in the laboratory using a shake table and in the field using dummie...

A proposed measurement of optical orbital and spin angular momentum and its implications for photon angular momentum

NASA Astrophysics Data System (ADS)

Leader, Elliot

2018-04-01

The expression for the total angular momentum carried by a laser optical vortex beam, splits, in the paraxial approximation, into two terms which seem to represent orbital and spin angular momentum respectively. There are, however, two very different competing versions of the formula for the spin angular momentum, one based on the use of the Poynting vector, as in classical electrodynamics, the other related to the canonical expression for the angular momentum which occurs in Quantum Electrodynamics. I analyze the possibility that a sufficiently sensitive optical measurement could decide which of these corresponds to the actual physical angular momentum carried by the beam.

A Computational Technique to Determine the Angular Displacement, Velocity and Momentum of a Human Body.

ERIC Educational Resources Information Center

Hay, James G.; Wilson, Barry D.

The angular momentum of a human body derived from both the angular velocity and angular displacement, utilizing cinematographic records has not been adequately assessed, prior to this study. Miller (1970) obtained the angular momentum but only during the airborne phase of activity. The method used by Ramey (1973) involved a force platform, but…

Difference in perception of angular displacement according to applied waveforms.

PubMed

Kushiro, Keisuke; Goto, Fumiyuki

2013-05-01

This study shows that the differences in the waveforms of angular rotation affect the perception and memory of angular displacement. During daily life, when we turn our head during various activities, our brain calculates how much angular displacement our head has undergone. However, how we obtain an accurate estimation of this angular displacement remains unclarified. This study aims to clarify this issue by investigating the perception and memory of passive rotation for three different waveforms of angular velocity rotation (sinusoidal (sine), triangle, and step). Thirteen healthy young subjects sitting on a servo-controlled chair were passively rotated at 60° or 120° about the earth-vertical axis by using one of these three angular velocity waveforms. They then attempted to reproduce the rotation angle by rotating the chair in the same direction in which they had been passively rotated using a handheld controller. The gain (reproduced angle/passively rotated angle) was calculated and used for the evaluation of the perception and memory of angular rotation. The gain for step rotation was larger than that for sine and triangle rotations, with statistical significance. This confirms that the difference in the waveforms of angular rotation affects the perception and memory of angular displacement.

Nontraditional method for determining unperturbed orbits of unknown space objects using incomplete optical observational data

NASA Astrophysics Data System (ADS)

Perov, N. I.

1985-02-01

A physical-geometrical method for computing the orbits of earth satellites on the basis of an inadequate number of angular observations (N3) was developed. Specifically, a new method has been developed for calculating the elements of Keplerian orbits of unidentified artificial satellites using two angular observations (alpha sub k, S sub k, k = 1). The first section gives procedures for determining the topocentric distance to AES on the basis of one optical observation. This is followed by description of a very simple method for determining unperturbed orbits using two satellite position vectors and a time interval which is applicable even in the case of antiparallel AED position vectors, a method designated the R sub 2 iterations method.

'Doing the writing' and 'working in parallel': how 'distal nursing' affects delegation and supervision in the emerging role of the newly qualified nurse.

PubMed

Johnson, Martin; Magnusson, Carin; Allan, Helen; Evans, Karen; Ball, Elaine; Horton, Khim; Curtis, Kathy; Westwood, Sue

2015-02-01

The role of the acute hospital nurse has moved away from the direct delivery of patient care and more towards the management of the delivery of bedside care by healthcare assistants. How newly qualified nurses delegate to and supervise healthcare assistants is important as failures can lead to care being missed, duplicated and/or incorrectly performed. The data described here form part of a wider study which explored how newly qualified nurses recontextualise knowledge into practice, and develop and apply effective delegation and supervision skills. This article analyses team working between newly qualified nurses and healthcare assistants, and nurses' balancing of administrative tasks with bedside care. Ethnographic case studies were undertaken in three hospital sites in England, using a mixed methods approach involving: participant observations; interviews with 33 newly qualified nurses, 10 healthcare assistants and 12 ward managers. Data were analysed using thematic analysis, aided by the qualitative software NVivo. Multiple demands upon the newly qualified nurses' time, particularly the pressures to maintain records, can influence how effectively they delegate to, and supervise, healthcare assistants. While some nurses and healthcare assistants work successfully together, others work 'in parallel' rather than as an efficient team. While some ward cultures and individual working styles promote effective team working, others lead to less efficient collaboration between newly qualified nurses and healthcare assistants. In particular the need for qualified nurses to maintain records can create a gap between them, and between nurses and patients. Newly qualified nurses require more assistance in managing their own time and developing successful working relationships with healthcare assistants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomechanical analysis of a newly designed bioabsorbable anterior cervical plate. Invited submission from the joint section meeting on disorders of the spine and peripheral nerves, March 2005.

PubMed

Ames, Christopher P; Acosta, Frank L; Chamberlain, Robert H; Larios, Adolfo Espinoza; Crawford, Neil R

2005-12-01

The authors present a biomechanical analysis of a newly designed bioabsorbable anterior cervical plate (ACP) for the treatment of one-level cervical degenerative disc disease. They studied anterior cervical discectomy and fusion (ACDF) in a human cadaveric model, comparing the stability of the cervical spine after placement of the bioabsorbable fusion plate, a bioabsorbable mesh, and a more traditional metallic ACP. Seven human cadaveric specimens underwent a C6-7 fibular graft-assisted ACDF placement. A one-level resorbable ACP was then placed and secured with bioabsorbable screws. Flexibility testing was performed on both intact and instrumented specimens using a servohydraulic system to create flexion-extension, lateral bending, and axial rotation motions. After data analysis, three parameters were calculated: angular range of motion, lax zone, and stiff zone. The results were compared with those obtained in a previous study of a resorbable fusion mesh and with those acquired using metallic fusion ACPs. For all parameters studied, the resorbable plate consistently conferred greater stability than the resorbable mesh. Moreover, it offered comparable stability with that of metallic fusion ACPs. Bioabsorbable plates provide better stability than resorbable mesh. Although the results of this study do not necessarily indicate that a resorbable plate confers equivalent stability to a metal plate, the resorbable ACP certainly yielded better results than the resorbable mesh. Bioabsorbable fusion ACPs should therefore be considered as alternatives to metal plates when a graft containment device is required.

Semiautomated skeletonization of the pulmonary arterial tree in micro-CT images

NASA Astrophysics Data System (ADS)

Hanger, Christopher C.; Haworth, Steven T.; Molthen, Robert C.; Dawson, Christopher A.

2001-05-01

We present a simple and robust approach that utilizes planar images at different angular rotations combined with unfiltered back-projection to locate the central axes of the pulmonary arterial tree. Three-dimensional points are selected interactively by the user. The computer calculates a sub- volume unfiltered back-projection orthogonal to the vector connecting the two points and centered on the first point. Because more x-rays are absorbed at the thickest portion of the vessel, in the unfiltered back-projection, the darkest pixel is assumed to be the center of the vessel. The computer replaces this point with the newly computer-calculated point. A second back-projection is calculated around the original point orthogonal to a vector connecting the newly-calculated first point and user-determined second point. The darkest pixel within the reconstruction is determined. The computer then replaces the second point with the XYZ coordinates of the darkest pixel within this second reconstruction. Following a vector based on a moving average of previously determined 3- dimensional points along the vessel's axis, the computer continues this skeletonization process until stopped by the user. The computer estimates the vessel diameter along the set of previously determined points using a method similar to the full width-half max algorithm. On all subsequent vessels, the process works the same way except that at each point, distances between the current point and all previously determined points along different vessels are determined. If the difference is less than the previously estimated diameter, the vessels are assumed to branch. This user/computer interaction continues until the vascular tree has been skeletonized.

CONNECTING ANGULAR MOMENTUM AND GALACTIC DYNAMICS: THE COMPLEX INTERPLAY BETWEEN SPIN, MASS, AND MORPHOLOGY

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

Teklu, Adelheid F.; Remus, Rhea-Silvia; Dolag, Klaus

The evolution and distribution of the angular momentum of dark matter (DM) halos have been discussed in several studies over the past decades. In particular, the idea arose that angular momentum conservation should allow us to infer the total angular momentum of the entire DM halo from measuring the angular momentum of the baryonic component, which is populating the center of the halo, especially for disk galaxies. To test this idea and to understand the connection between the angular momentum of the DM halo and its galaxy, we use a state-of-the-art, hydrodynamical cosmological simulation taken from the set of Magneticummore » Pathfinder simulations. Thanks to the inclusion of the relevant physical processes, the improved underlying numerical methods, and high spatial resolution, we successfully produce populations of spheroidal and disk galaxies self-consistently. Thus, we are able to study the dependence of galactic properties on their morphology. We find that (1) the specific angular momentum of stars in disk and spheroidal galaxies as a function of their stellar mass compares well with observational results; (2) the specific angular momentum of the stars in disk galaxies is slightly smaller compared to the specific angular momentum of the cold gas, in good agreement with observations; (3) simulations including the baryonic component show a dichotomy in the specific stellar angular momentum distribution when splitting the galaxies according to their morphological type (this dichotomy can also be seen in the spin parameter, where disk galaxies populate halos with slightly larger spin compared to spheroidal galaxies); (4) disk galaxies preferentially populate halos in which the angular momentum vector of the DM component in the central part shows a better alignment to the angular momentum vector of the entire halo; and (5) the specific angular momentum of the cold gas in disk galaxies is approximately 40% smaller than the specific angular momentum of the total DM halo and shows a significant scatter.« less

A Comparison between 3D Model Results Using Two Different Collision Schemes: Forward Scattering vs. Hard Sphere Collision

NASA Astrophysics Data System (ADS)

Lee, Y.; Combi, M. R.; Tenishev, V.; Bougher, S. W.; Johnson, R. E.; Tully, C.

2016-12-01

The recent observations of the Martian geomorphology suggest that water has played a critical role in forming the present status of the Martian atmosphere and environment. The inventory of water has been depleted throughout the planet's geologic time via various mechanisms from the surface to the uppermost atmosphere where the Sun-Mars interaction occurs. During the current epoch, dissociative recombination of O2+ is suggested as the main nonthermal mechanism that regulates the escape of atomic O, forming the hot O corona. A nascent hot O atom produced deep in the thermosphere undergoes collisions with the background thermal species, where the particle can lose energy and become thermalized before it reaches the collisionless regime and escape. The major hot O collisions with the background species that contribute to the thermalization of hot O are Ohot-Ocold, Ohot-CO2,cold, Ohot-COcold, and Ohot-N2,cold. In order to describe these collisions, there have been different collisions schemes used by the previous models. One of the most realistic descriptions involves using angular differential cross sections, and the simplest approach is using isotropic collision cross sections. Here, we present a comparison between the 3D model results using two different collision schemes to find equivalent hard sphere collision cross sections that satisfy the effects from using forward scattering cross sections. We adapted the newly calculated angular differential cross sections to the major hot O collisions. The hot O corona is simulated by coupling our Mars application of the 3D Adaptive Mesh Particle Simulator (M-AMPS) [Tenishev et al., 2008, 2013] and the Mars Global Ionosphere-Thermosphere Model (M-GITM) [Bougher et al., 2015].

Beyond Born-Oppenheimer theory for ab initio constructed diabatic potential energy surfaces of singlet H3+ to study reaction dynamics using coupled 3D time-dependent wave-packet approach.

PubMed

Ghosh, Sandip; Mukherjee, Saikat; Mukherjee, Bijit; Mandal, Souvik; Sharma, Rahul; Chaudhury, Pinaki; Adhikari, Satrajit

2017-08-21

The workability of beyond Born-Oppenheimer theory to construct diabatic potential energy surfaces (PESs) of a charge transfer atom-diatom collision process has been explored by performing scattering calculations to extract accurate integral cross sections (ICSs) and rate constants for comparison with most recent experimental quantities. We calculate non-adiabatic coupling terms among the lowest three singlet states of H 3 + system (1 1 A ' , 2 1 A ' , and 3 1 A ' ) using MRCI level of calculation and solve the adiabatic-diabatic transformation equation to formulate the diabatic Hamiltonian matrix of the same process [S. Mukherjee et al., J. Chem. Phys. 141, 204306 (2014)] for the entire region of nuclear configuration space. The nonadiabatic effects in the D + + H 2 reaction has been studied by implementing the coupled 3D time-dependent wave packet formalism in hyperspherical coordinates [S. Adhikari and A. J. C. Varandas, Comput. Phys. Commun. 184, 270 (2013)] with zero and non-zero total angular momentum (J) on such newly constructed accurate (ab initio) diabatic PESs of H 3 + . We have depicted the convergence profiles of reaction probabilities for the reactive non-charge transfer, non-reactive charge transfer, and reactive charge transfer processes for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. Finally, total and state-to-state ICSs are calculated as a function of collision energy for the initial rovibrational state (v = 0, j = 0) of the H 2 molecule, and consequently, those quantities are compared with previous theoretical and experimental results.

Optical Flares and a Long-lived Dark Spot on a Cool Shallow Contact Binary

NASA Astrophysics Data System (ADS)

Qian, S.-B.; Wang, J.-J.; Zhu, L.-Y.; Snoonthornthum, B.; Wang, L.-Z.; Zhao, E. G.; Zhou, X.; Liao, W.-P.; Liu, N.-P.

2014-05-01

W UMa-type stars are contact systems where both cool components fill the critical Roche lobes and share a common convective envelope. Long and unbroken time-series photometry is expected to play an important role in their origin and activity. The newly discovered short-period W UMa-type star, CSTAR 038663, was monitored continuously by Chinese Small Telescope ARray (CSTAR) in Antarctica during the winters of 2008 and 2010. There were 15 optical flares recorded in the i band during the winter of 2010. This was the first time such flares were detected from a W UMa-type star. By analyzing the nearly unbroken photometric data from 2008, it is discovered that CSTAR 038663 is a W-type shallow contact binary system (f = 10.6(± 2.9)%) with a high mass ratio of q = 1.12(± 0.01), where the less massive component is slightly hotter than the more massive one. The asymmetric light curves are explained by the presence of a dark spot on the more massive component. Its temperature is about 800 K lower than the stellar photosphere and it covers 2.1% of the total photospheric surface. The lifetime of the dark spot is longer than 116 days. Using 725 eclipse times, we found that the observed-calculated (O-C) curve may show a cyclic variation that is explained by the presence of a close-in third body. Both the shallow contact configuration and the extremely high mass ratio suggest that CSTAR 038663 is presently evolving into a contact system with little mass transfer. The formation and evolution is driven by the loss of angular momentum via magnetic braking, and the close-in companion star is expected to play an important role, removing angular momentum from the central eclipsing binary.

Microstructure characterization of LAE442 magnesium alloy processed by extrusion and ECAP

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

Minárik, Peter; Král, Robert; Pešička, Josef

2016-02-15

The magnesium alloy LAE442 was processed by extrusion and equal channel angular pressing (ECAP) to achieve ultrafine grained microstructure. Detailed characterization of the microstructure was performed by scanning electron microscope, electron back scattered diffraction (EBSD) and transmission electron microscope. The initial, as-cast, microstructure consisted of large grains of ~ 1 mm. The grain refinement due to the processing by severe plastic deformation led to a decrease of the average grain size to ~ 1.7 μm after the final step of ECAP. A detailed characterization of secondary phases showed the precipitation of Al{sub 11}RE{sub 3}, Al{sub 2}Ca and Al{sub 10}RE{sub 2}Mn{submore » 7} intermetallic phases. X-ray diffraction measurements proved that Li is dissolved within the magnesium matrix in the as-cast condition. Newly formed Al{sub 3}Li phase was observed after ECAP. The texture formation due to the extrusion and ECAP was different from that in the other magnesium alloys due to the activation of non-basal slip systems as a result of the decrease of the c/a ratio. - Highlights: • Combined extrusion and equal channel angular pressing results in significant grain refinement by factor 1000 approximately. • Al{sub 11}RE{sub 3}, Al{sub 2}Ca and Al{sub 10}RE{sub 2}Mn{sub 7} secondary phases are present in the as-cast material while Li was dissolved in the Mg matrix. • Extrusion and ECAP have no effect on the composition of the secondary phases but they influence strongly their distribution. • Texture evolution is affected by decrease of c/a ratio due to the presence of Li and resulting activation of non-basal slip.« less

Differential and integral cross sections for the rotationally inelastic scattering of methyl radicals with H2 and D2

NASA Astrophysics Data System (ADS)

Tkáč, Ondřej; Ma, Qianli; Rusher, Cassandra A.; Greaves, Stuart J.; Orr-Ewing, Andrew J.; Dagdigian, Paul J.

2014-05-01

Comparisons are presented of experimental and theoretical studies of the rotationally inelastic scattering of CD3 radicals with H2 and D2 collision partners at respective collision energies of 680 ± 75 and 640 ± 60 cm-1. Close-coupling quantum-mechanical calculations performed using a newly constructed ab initio potential energy surface (PES) provide initial-to-final CD3 rotational level (n, k → n', k') integral and differential cross sections (ICSs and DCSs). The DCSs are compared with crossed molecular beam and velocity map imaging measurements of angular scattering distributions, which serve as a critical test of the accuracy of the new PES. In general, there is very good agreement between the experimental measurements and the calculations. The DCSs for CD3 scattering from both H2 and D2 peak in the forward hemisphere for n' = 2-4 and shift more to sideways and backward scattering for n' = 5. For n' = 6-8, the DCSs are dominated by backward scattering. DCSs for a particular CD3 n → n' transition have a similar angular dependence with either D2 or H2 as collision partner. Any differences between DCSs or ICSs can be attributed to mass effects because the PES is unchanged for CD3-H2 and CD3-D2 collisions. Further comparisons are drawn between the CD3-D2 scattering and results for CD3-He presented in our recent paper [O. Tkáč, A. G. Sage, S. J. Greaves, A. J. Orr-Ewing, P. J. Dagdigian, Q. Ma, and M. H. Alexander, Chem. Sci. 4, 4199 (2013)]. These systems have the same reduced mass, but are governed by different PESs.

Optical angular momentum and atoms

PubMed Central

2017-01-01

Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom’s angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light’s OAM, aiding our fundamental understanding of light–matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069766

Vibration signal correction of unbalanced rotor due to angular speed fluctuation

NASA Astrophysics Data System (ADS)

Cao, Hongrui; He, Dong; Xi, Songtao; Chen, Xuefeng

2018-07-01

The rotating speed of a rotor is hardly constant in practice due to angular speed fluctuation, which affects the balancing accuracy of the rotor. In this paper, the effect of angular speed fluctuation on vibration responses of the unbalanced rotor is analyzed quantitatively. Then, a vibration signal correction method based on zoom synchrosqueezing transform (ZST) and tacholess order tracking is proposed. The instantaneous angular speed (IAS) of the rotor is extracted by the ZST firstly and then used to calculate the instantaneous phase. The vibration signal is further resampled in angular domain to reduce the effect of angular speed fluctuation. The signal obtained in angular domain is transformed into order domain using discrete Fourier transform (DFT) to estimate the amplitude and phase of the vibration signal. Simulated and experimental results show that the proposed method can successfully correct the amplitude and phase of the vibration signal due to angular speed fluctuation.

Optimized image acquisition for breast tomosynthesis in projection and reconstruction space.

PubMed

Chawla, Amarpreet S; Lo, Joseph Y; Baker, Jay A; Samei, Ehsan

2009-11-01

Breast tomosynthesis has been an exciting new development in the field of breast imaging. While the diagnostic improvement via tomosynthesis is notable, the full potential of tomosynthesis has not yet been realized. This may be attributed to the dependency of the diagnostic quality of tomosynthesis on multiple variables, each of which needs to be optimized. Those include dose, number of angular projections, and the total angular span of those projections. In this study, the authors investigated the effects of these acquisition parameters on the overall diagnostic image quality of breast tomosynthesis in both the projection and reconstruction space. Five mastectomy specimens were imaged using a prototype tomosynthesis system. 25 angular projections of each specimen were acquired at 6.2 times typical single-view clinical dose level. Images at lower dose levels were then simulated using a noise modification routine. Each projection image was supplemented with 84 simulated 3 mm 3D lesions embedded at the center of 84 nonoverlapping ROIs. The projection images were then reconstructed using a filtered backprojection algorithm at different combinations of acquisition parameters to investigate which of the many possible combinations maximizes the performance. Performance was evaluated in terms of a Laguerre-Gauss channelized Hotelling observer model-based measure of lesion detectability. The analysis was also performed without reconstruction by combining the model results from projection images using Bayesian decision fusion algorithm. The effect of acquisition parameters on projection images and reconstructed slices were then compared to derive an optimization rule for tomosynthesis. The results indicated that projection images yield comparable but higher performance than reconstructed images. Both modes, however, offered similar trends: Performance improved with an increase in the total acquisition dose level and the angular span. Using a constant dose level and angular span, the performance rolled off beyond a certain number of projections, indicating that simply increasing the number of projections in tomosynthesis may not necessarily improve its performance. The best performance for both projection images and tomosynthesis slices was obtained for 15-17 projections spanning an angular are of approximately 45 degrees--the maximum tested in our study, and for an acquisition dose equal to single-view mammography. The optimization framework developed in this framework is applicable to other reconstruction techniques and other multiprojection systems.

Development of manufacturing systems for nanocrystalline and ultra-fine grain materials employing indexing equal channel angular pressing

NASA Astrophysics Data System (ADS)

Hester, Michael Wayne

Nanotechnology offers significant opportunities in providing solutions to existing engineering problems as well as breakthroughs in new fields of science and technology. In order to fully realize benefits from such initiatives, nanomanufacturing methods must be developed to integrate enabling constructs into commercial mainstream. Even though significant advances have been made, widespread industrialization in many areas remains limited. Manufacturing methods, therefore, must continually be developed to bridge gaps between nanoscience discovery and commercialization. A promising technology for integration of top-down nanomanufacturing yet to receive full industrialization is equal channel angular pressing, a process transforming metallic materials into nanostructured or ultra-fine grained materials with significantly improved performance characteristics. To bridge the gap between process potential and actual manufacturing output, a prototype top-down nanomanufacturing system identified as indexing equal channel angular pressing (IX-ECAP) was developed. The unit was designed to capitalize on opportunities of transforming spent or scrap engineering elements into key engineering commodities. A manufacturing system was constructed to impose severe plastic deformation via simple shear in an equal channel angular pressing die on 1100 and 4043 aluminum welding rods. 1/4 fraction factorial split-plot experiments assessed significance of five predictors on the response, microhardness, for the 4043 alloy. Predictor variables included temperature, number of passes, pressing speed, back pressure, and vibration. Main effects were studied employing a resolution III design. Multiple linear regression was used for model development. Initial studies were performed using continuous processing followed by contingency designs involving discrete variable length work pieces. IX-ECAP offered a viable solution in severe plastic deformation processing. Discrete variable length work piece pressing proved very successful. With three passes through the system, 4043 processed material experienced an 88.88% increase in microhardness, 203.4% increase in converted yield strength, and a 98.5% reduction in theoretical final grain size to 103 nanometers using the Hall-Petch relation. The process factor, number of passes, was statistically significant at the 95% confidence level; whereas, temperature was significant at the 90% confidence level. Limitations of system components precluded completion of studies involving continuous pressing. Proposed system redesigns, however, will ensure mainstream commercialization of continuous length work piece processing.

Development of wide-angle 2D light scattering static cytometry

NASA Astrophysics Data System (ADS)

Xie, Linyan; Liu, Qiao; Shao, Changshun; Su, Xuantao

2016-10-01

We have recently developed a 2D light scattering static cytometer for cellular analysis in a label-free manner, which measures side scatter (SSC) light in the polar angular range from 79 to 101 degrees. Compared with conventional flow cytometry, our cytometric technique requires no fluorescent labeling of the cells, and static cytometry measurements can be performed without flow control. In this paper we present an improved label-free static cytometer that can obtain 2D light scattering patterns in a wider angular range. By illuminating the static microspheres on chip with a scanning optical fiber, wide-angle 2D light scattering patterns of single standard microspheres with a mean diameter of 3.87 μm are obtained. The 2D patterns of 3.87 μm microspheres contain both large-angle forward scatter (FSC) and SSC light in the polar angular range from 40 to 100 degrees, approximately. Experimental 2D patterns of 3.87 μm microspheres are in good agreement with Mie theory simulated ones. The wide-angle light scattering measurements may provide a better resolution for particle analysis as compared with the SSC measurements. Two dimensional light scattering patterns of HL-60 human acute leukemia cells are obtained by using our static cytometer. Compared with SSC 2D light scattering patterns, wide-angle 2D patterns contain richer information of the HL-60 cells. The obtaining of 2D light scattering patterns in a wide angular range could help to enhance the capabilities of our label-free static cytometry for cell analysis.

Quaternion-based study of angular velocity of the cardiac vector during myocardial ischaemia.

PubMed

Cruces, Pablo Daniel; Arini, Pedro David

2017-12-01

Early detection of acute ischaemia through non-invasive methods remains a challenge in health research. Ischaemic condition caused by a decrease in the blood supply in a cardiac region induces hypoxia and metabolic abnormalities that contribute to the electrical instability of the heart and to the development of slow conduction in damaged tissue. Herein, a percutaneous transluminal coronary angiography (PTCA) is considered as a model of supply ischaemia. We use the concept of quaternion to develop a robust method for assessing the angular velocity of cardiac vector in the orthogonal XYZ leads obtained from 92 patients undergoing the PTCA procedure. The maxima of angular velocity in both ventricular depolarization and repolarization are combined with traditional linear velocity indexes in order to obtain a detector of ischaemic episodes (Ischaemia Detector, ID). ID achieves 98%/100% of sensitivity/specificity when differentiating healthy subjects from patients with early ischaemia. Furthermore, it also shows high accuracy when the comparison is made between ischaemic subjects and patients with different non-ischaemic pathologic ST-deviations which are known to cause false positives, reaching 95%/98% of sensitivity/specificity. Moreover, the study of significant reductions (p<0.001) of angular velocity components allows extraction of distinct ischaemic common features which are useful for analyzing the dependence of vectorcardiogram signal on each site of occlusion. The sensitivity of injury location reaches values of 88% (RCA), 87% (LAD) and 80% (LCx). The high performance of the proposed method establishes a promising outcome for application in computerized assistance in clinical practice. Copyright © 2017 Elsevier B.V. All rights reserved.

Angular-Rate Estimation Using Quaternion Measurements

NASA Technical Reports Server (NTRS)

Azor, Ruth; Bar-Itzhack, Y.; Deutschmann, Julie K.; Harman, Richard R.

1998-01-01

In most spacecraft (SC) there is a need to know the SC angular rate. Precise angular rate is required for attitude determination, and a coarse rate is needed for attitude control damping. Classically, angular rate information is obtained from gyro measurements. These days, there is a tendency to build smaller, lighter and cheaper SC, therefore the inclination now is to do away with gyros and use other means and methods to determine the angular rate. The latter is also needed even in gyro equipped satellites when performing high rate maneuvers whose angular-rate is out of range of the on board gyros or in case of gyro failure. There are several ways to obtain the angular rate in a gyro-less SC. When the attitude is known, one can differentiate the attitude in whatever parameters it is given and use the kinematics equation that connects the derivative of the attitude with the satellite angular-rate and compute the latter. Since SC usually utilize vector measurements for attitude determination, the differentiation of the attitude introduces a considerable noise component in the computed angular-rate vector.

Cosmic microwave background polarimetry with ABS and ACT: Instrumental design, characterization, and analysis

NASA Astrophysics Data System (ADS)

Simon, Sara Michelle

The LCDM model of the universe is supported by an abundance of astronomical observations, but it does not confirm a period of inflation in the early universe or explain the nature of dark energy and dark matter. The polarization of the cosmic microwave background (CMB) may hold the key to addressing these profound questions. If a period of inflation occurred in the early universe, it could have left a detectable odd-parity pattern called B-modes in the polarization of the CMB on large angular scales. Additionally, the CMB can be used to probe the structure of the universe on small angular scales through lensing and the detection of galaxy clusters and their motions via the Sunyaev-Zel'dovich effect, which can improve our understanding of neutrinos, dark matter, and dark energy. The Atacama B-mode Search (ABS) instrument was a cryogenic crossed-Dragone telescope located at an elevation of 5190m in the Atacama Desert in Chile that observed from February 2012 until October 2014. ABS searched on degree-angular scales for inflationary B-modes in the CMB and pioneered the use of a rapidly-rotating half-wave plate (HWP), which modulates the polarization of incoming light to permit the measurement of celestial polarization on large angular scales that would otherwise be obscured by 1/f noise from the atmosphere. Located next to ABS in the Atacama is the Atacama Cosmology Telescope (ACT), which is an off-axis Gregorian telescope. Its large 6m primary mirror facilitates measurements of the CMB on small angular scales. HWPs are baselined for use with the upgraded polarization-sensitive camera for ACT, called Advanced ACTPol, to extend observations of the polarized CMB to larger angular scales while also retaining sensitivity to small angular scales. The B-mode signal is extremely faint, and measuring it poses an instrumental challenge that requires the development of new technologies and well-characterized instruments. I will discuss the use of novel instrumentation and methods on the ABS telescope and Advanced ACTPol, the characterization of the ABS instrument, and the first two seasons of ABS data, including an overview of the data selection process.

The clinical features of angular cheilitis occurring during orthodontic treatment: a multi-centre observational study.

PubMed

Cross, David; Eide, May L; Kotinas, Anastasios

2010-06-01

To report the prevalence and clinical features of angular cheilitis occurring in patients undergoing orthodontic treatment. Cross-sectional, observational study. Three centres were involved; Glasgow Dental Hospital and two specialist orthodontic practices, one in Scotland and one in Greece. Six hundred and sixty consecutive patients undergoing orthodontic treatment were examined over a 9 month period. The presence and absence of angular cheilitis was recorded. A six-point clinical scale was used to describe the clinical features of angular cheilitis when present. Chi-squared tests were used to investigate the association between the presence of angular cheilitis and oral hygiene level/appliance type. Eleven per cent of orthodontic patients in this Western European population, showed signs of angular cheilitis. No correlation was found between the presence of angular cheilitis and gender. Good oral hygiene was associated with a reduced prevalence (P<0.01). Angular cheilitis is a multifactorial condition that can occur in a small percentage of patients during orthodontic treatment. Good oral hygiene may be associated with a reduced risk. A new clinical grade of angular cheilitis is suggested that may help future research. Further studies are required to investigate the microbiological features associated with angular cheilitis occurring in orthodontic patients, as well as associations with medical conditions, such as asthma.

Development of a computerized intervertebral motion analysis of the cervical spine for clinical application.

PubMed

Piché, Mathieu; Benoît, Pierre; Lambert, Julie; Barrette, Virginie; Grondin, Emmanuelle; Martel, Julie; Paré, Amélie; Cardin, André

2007-01-01

The objective of this study was to develop a measurement method that could be implemented in chiropractic for the evaluation of angular and translational intervertebral motion of the cervical spine. Flexion-extension radiographs were digitized with a scanner at a ratio of 1:1 and imported into a software, allowing segmental motion measurements. The measurements were obtained by selecting the most anteroinferior point and the most posteroinferior point of a vertebral body (anterior and posterior arch, respectively, for C1), with the origin of the reference frame set at the most posteroinferior point of the vertebral body below. The same procedure was performed for both the flexion and extension radiographs, and the coordinates of the 2 points were used to calculate the angular movement and the translation between the 2 vertebrae. This method provides a measure of intervertebral angular and translational movement. It uses a different reference frame for each joint instead of the same reference frame for all joints and thus provides a measure of motion in the plane of each articulation. The calculated values obtained are comparable to other studies on intervertebral motion and support further development to validate the method. The present study proposes a computerized procedure to evaluate intervertebral motion of the cervical spine. This procedure needs to be validated with a reliability study but could provide a valuable tool for doctors of chiropractic and further spinal research.

REM sleep selectively prunes and maintains new synapses in development and learning

PubMed Central

Li, Wei; Ma, Lei; Yang, Guang; Gan, Wenbiao

2017-01-01

The functions and underlying mechanisms of rapid eye movement (REM) sleep remain unclear. Here we show that REM sleep prunes newly-formed postsynaptic dendritic spines of layer 5 pyramidal neurons in the mouse motor cortex during development and motor learning. This REM sleep-dependent elimination of new spines facilitates subsequent spine formation in development and when a new motor task is learned, indicating a role of REM sleep in pruning to balance the number of new spines formed over time. In addition, REM sleep also strengthens and maintains some newly-formed spines that are critical for neuronal circuit development and behavioral improvement after learning. We further show that dendritic calcium spikes arising during REM sleep are important for pruning and strengthening of new spines. Together, these findings indicate that REM sleep has multifaceted functions in brain development, learning, and memory consolidation by selectively eliminating and maintaining newly-formed synapses via dendritic calcium spike-dependent mechanisms. PMID:28092659

SU-E-T-472: Improvement of IMRT QA Passing Rate by Correcting Angular Dependence of MatriXX

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

Chen, Q; Watkins, W; Kim, T

2015-06-15

Purpose: Multi-channel planar detector arrays utilized for IMRT-QA, such as the MatriXX, exhibit an incident-beam angular dependent response which can Result in false-positive gamma-based QA results, especially for helical tomotherapy plans which encompass the full range of beam angles. Although MatriXX can use with gantry angle sensor to provide automatically angular correction, this sensor does not work with tomotherapy. The purpose of the study is to reduce IMRT-QA false-positives by correcting for the MatriXX angular dependence. Methods: MatriXX angular dependence was characterized by comparing multiple fixed-angle irradiation measurements with corresponding TPS computed doses. For 81 Tomo-helical IMRT-QA measurements, two differentmore » correction schemes were tested: (1) A Monte-Carlo dose engine was used to compute MatriXX signal based on the angular-response curve. The computed signal was then compared with measurement. (2) Uncorrected computed signal was compared with measurements uniformly scaled to account for the average angular dependence. Three scaling factor (+2%, +2.5%, +3%) were tested. Results: The MatriXX response is 8% less than predicted for a PA beam even when the couch is fully accounted for. Without angular correction, only 67% of the cases pass the >90% points γ<1 (3%, 3mm). After full angular correction, 96% of the cases pass the criteria. Of three scaling factors, +2% gave the highest passing rate (89%), which is still less than the full angular correction method. With a stricter γ(2%,3mm) criteria, the full angular correction method was still able to achieve the 90% passing rate while the scaling method only gives 53% passing rate. Conclusion: Correction for the MatriXX angular dependence reduced the false-positives rate of our IMRT-QA process. It is necessary to correct for the angular dependence to achieve the IMRT passing criteria specified in TG129.« less

Twisted molecular excitons as mediators for changing the angular momentum of light

NASA Astrophysics Data System (ADS)

Zang, Xiaoning; Lusk, Mark T.

2017-07-01

Molecules with CN or CN h symmetry can absorb quanta of optical angular momentum to generate twisted excitons with well-defined quasiangular momenta of their own. Angular momentum is conserved in such interactions at the level of a paraxial approximation for the light beam. A sequence of absorption events can thus be used to create a range of excitonic angular momenta. Subsequent decay can produce radiation with a single angular momentum equal to that accumulated. Such molecules can thus be viewed as mediators for changing the angular momentum of light. This sidesteps the need to exploit nonlinear light-matter interactions based on higher-order susceptibilities. A tight-binding paradigm is used to verify angular momentum conservation and demonstrate how it can be exploited to change the angular momentum of light. The approach is then extended to a time-dependent density functional theory setting where the key results are shown to hold in a many-body, multilevel setting.

Factors influencing perceived angular velocity.

PubMed

Kaiser, M K; Calderone, J B

1991-11-01

The assumption that humans are able to perceive and process angular kinematics is critical to many structure-from-motion and optical flow models. The current studies investigate this sensitivity, and examine several factors likely to influence angular velocity perception. In particular, three factors are considered: (1) the extent to which perceived angular velocity is determined by edge transitions of surface elements, (2) the extent to which angular velocity estimates are influenced by instantaneous linear velocities of surface elements, and (3) whether element-velocity effects are related to three-dimensional (3-D) tangential velocities or to two-dimensional (2-D) image velocities. Edge-transition rate biased angular velocity estimates only when edges were highly salient. Element velocities influenced perceived angular velocity; this bias was related to 2-D image velocity rather than 3-D tangential velocity. Despite these biases, however, judgments were most strongly determined by the true angular velocity. Sensitivity to this higher order motion parameter was surprisingly good, for rotations both in depth (y-axis) and parallel to the line of sight (z-axis).

X-ray investigation of cross-breed silk in cocoon, yarn and fabric forms

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

Radhalakshmi, Y. C.; Kariappa,; Siddaraju, G. N.

2012-06-05

Recently Central Sericulture Research and Training Institute, Mysore developed many improved cross breeds and bivoltine hybrids. Newly developed cross breeds recorded fibre characteristics which are significantly superior over existing control hybrids. This aspect has been investigated using X-ray diffraction technique. We have employed line profile analysis to compute microstructural parameters. These parameters are compared with physical parameters of newly developed cross breed silk fibers for a better understanding of structure-property relation in these samples.

Molecular alignment and orientation with a hybrid Raman scattering technique

NASA Astrophysics Data System (ADS)

Bustard, Philip J.; Lausten, R.; Sussman, Benjamin J.

2012-11-01

We demonstrate a scheme for the preparation of molecular alignment and angular momentum orientation using a hybrid combination of two limits of Raman scattering. First a weak, impulsive pump pulse initializes the system via the nonresonant dynamic Stark effect. Then, having overcome the influence of the vacuum fluctuations, an amplification pulse selectively enhances the initial coherences by transient stimulated Raman scattering, generating alignment and angular momentum orientation of molecular hydrogen. The amplitude and phase of the resulting coherent dynamics are experimentally probed, indicating an amplification factor of 4.5. An analytic theory is developed to model the dynamics.

Novel measuring strategies in neutron interferometry

NASA Astrophysics Data System (ADS)

Bonse, Ulrich; Wroblewski, Thomas

1985-04-01

Angular misalignment of a sample in a single crystal neutron interferometer leads to systematic errors of the effective sample thickness and in this way to errors in the determination of the coherent scattering length. The misalignment can be determined and the errors can be corrected by a second measurement at a different angular sample position. Furthermore, a method has been developed which allows supervision of the wavelength during the measurements. These two techniques were tested by determining the scattering length of copper. A value of bc = 7.66(4) fm was obtained which is in excellent agreement with previous measurements.

The photon gas formulation of thermal radiation

NASA Technical Reports Server (NTRS)

Ried, R. C., Jr.

1975-01-01

A statistical consideration of the energy, the linear momentum, and the angular momentum of the photons that make up a thermal radiation field was presented. A general nonequilibrium statistical thermodynamics approach toward a macroscopic description of thermal radiation transport was developed and then applied to the restricted equilibrium statistical thermostatics derivation of the energy, linear momentum, and intrinsic angular momentum equations for an isotropic photon gas. A brief treatment of a nonisotropic photon gas, as an example of the results produced by the nonequilibrium statistical thermodynamics approach, was given. The relativistic variation of temperature and the invariance of entropy were illustrated.

Electromagnetic scattering from a layer of finite length, randomly oriented, dielectric, circular cylinders over a rough interface with application to vegetation

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.

1988-01-01

A scattering model for defoliated vegetation is developed by treating a layer of defoliated vegetation as a collection of randomly oriented dielectric cylinders of finite length over an irregular ground surface. Both polarized and depolarized backscattering are computed and their behavior versus the volume fraction, the incidence angle, the frequency, the angular distribution and the cylinder size are illustrated. It is found that both the angular distribution and the cylinder size have significant effects on the backscattered signal. The present theory is compared with measurements from defoliated vegetations.

The spectroscopic characterization of newly developed emissive materials and the effects of environment on their photophysical properties

NASA Astrophysics Data System (ADS)

McNamara, Louis Edward, III

The development of new materials capable of efficient charge transfer and energy storage has become increasingly important in many areas of modern chemical research. This is especially true for the development of emissive optoelectronic devices and in the field of solar to electric energy conversion. The characterization of the photophysical properties of new molecular systems for these applications has become critical in the design and development of these materials. Many molecular building blocks have been developed and understanding the properties of these molecules at a fundamental level is essential for their successful implementation and future engineering. This dissertation focuses on the characterization of some of these newly-developed molecular systems. The spectroscopic studies focus on the characterization of newly-developed molecules based on perylene and indolizine derivatives for solar to electric energy conversion, thienopyrazine derivatives for near infrared (NIR) emissive applications, an SCS pincer complex for blue emissive materials and a fluorescent probe for medical applications. The effects of noncovalent interactions are also investigated on these systems and a benchmark biological molecule trimethylamine N-oxide (TMAO).

Newly Developed Techniques on Polycondensation, Ring-Opening Polymerization and Polymer Modification: Focus on Poly(Lactic Acid)

PubMed Central

Hu, Yunzi; Daoud, Walid A.; Cheuk, Kevin Ka Leung; Lin, Carol Sze Ki

2016-01-01

Polycondensation and ring-opening polymerization are two important polymer synthesis methods. Poly(lactic acid), the most typical biodegradable polymer, has been researched extensively from 1900s. It is of significant importance to have an up-to-date review on the recent improvement in techniques for biodegradable polymers. This review takes poly(lactic acid) as the example to present newly developed polymer synthesis techniques on polycondensation and ring-opening polymerization reported in the recent decade (2005–2015) on the basis of industrial technique modifications and advanced laboratory research. Different polymerization methods, including various solvents, heating programs, reaction apparatus and catalyst systems, are summarized and compared with the current industrial production situation. Newly developed modification techniques for polymer properties improvement are also discussed based on the case of poly(lactic acid). PMID:28773260

Mitigation of radiation-pressure-induced angular instability of a Fabry-Perot cavity consisting of suspended mirrors

NASA Astrophysics Data System (ADS)

Nagano, Koji; Enomoto, Yutaro; Nakano, Masayuki; Furusawa, Akira; Kawamura, Seiji

2016-12-01

To observe radiation pressure noise in optical cavities consisting of suspended mirrors, high laser power is necessary. However, because the radiation pressure on the mirrors could cause an angular anti-spring effect, the high laser power could induce angular instability to the cavity. An angular control system using radiation pressure as an actuator, which was previously invented to reduce the anti-spring effect for the low power case, was applied to the higher power case where the angular instability would occur. As a result the angular instability was mitigated. It was also demonstrated that the cavity was unstable without this control system.

Break-technique handheld dynamometry: relation between angular velocity and strength measurements.

PubMed

Burns, Stephen P; Spanier, David E

2005-07-01

To determine whether the muscle strength, as measured with break-technique handheld dynamometry (HHD), is dependent on the angular velocity achieved during testing and to compare reliability at different angular velocities. Repeated-measures study. Participants underwent HHD by using make-technique (isometric) and break-technique (eccentric) dynamometry at 3 prespecified angular velocities. Elbow movement was recorded with an electrogoniometer. Inpatient spinal cord injury unit. Convenience sample of 20 persons with tetraplegia with weakness of elbow flexors or extensors. Not applicable. Elbow angular velocity and muscle strength recorded during HHD. With the break technique, angular velocities averaging 15 degrees , 33 degrees , and 55 degrees /s produced 16%, 30%, and 51% greater strength measurements, respectively, than velocities recorded by using the make technique (all P < .006 for comparisons between successive techniques). The intraclass correlation coefficient for intrarater reliability was .89 or greater for all testing techniques. Greater strength is recorded with faster angular velocities during HHD. Differences in angular velocity may explain the wide range previously reported for break- versus make-technique strength measurements. Variation in angular velocity is a potential source of variability in serial HHD strength measurements, and for this reason the make technique may be preferable.

New theoretical results in synchrotron radiation

NASA Astrophysics Data System (ADS)

Bagrov, V. G.; Gitman, D. M.; Tlyachev, V. B.; Jarovoi, A. T.

2005-11-01

One of the remarkable features of the relativistic electron synchrotron radiation is its concentration in small angle Δ ≈ 1/γ (here γ-relativistic factor: γ = E/mc2, E energy, m electron rest mass, c light velocity) near rotation orbit plane [V.G. Bagrov, V.A. Bordovitsyn, V.G. Bulenok, V. Ya. Epp, Kinematical projection of pulsar synchrotron radiation profiles, in: Proceedings of IV ISTC Scientific Advisory Commitee Seminar on Basic Science in ISTC Aktivities, Akademgorodok, Novosibirsk, April 23 27, 2001, p. 293 300]. This theoretically predicted and experimentally confirmed feature is peculiar to total (spectrum summarized) radiating intensity. This angular distribution property has been supposed to be (at least qualitatively) conserved and for separate spectrum synchrotron radiation components. In the work of V.G. Bagrov, V.A. Bordovitsyn, V. Ch. Zhukovskii, Development of the theory of synchrotron radiation and related processes. Synchrotron source of JINR: the perspective of research, in: The Materials of the Second International Work Conference, Dubna, April 2 6, 2001, pp. 15 30 and in Angular dependence of synchrotron radiation intensity. http://lanl.arXiv.org/abs/physics/0209097, it is shown that the angular distribution of separate synchrotron radiation spectrum components demonstrates directly inverse tendency the angular distribution deconcentration relatively the orbit plane takes place with electron energy growth. The present work is devoted to detailed investigation of this situation. For exact quantitative estimation of angular concentration degree of synchrotron radiation the definition of radiation effective angle and deviation angle is proposed. For different polarization components of radiation the dependence of introduced characteristics was investigated as a functions of electron energy and number of spectrum component.

Development of realtime connected element interferometry at the Goldstone Deep Space Communications Complex

NASA Technical Reports Server (NTRS)

Edwards, C. D.

1990-01-01

Connected-element interferometry (CEI) has the potential to provide high-accuracy angular spacecraft tracking on short baselines by making use of the very precise phase delay observable. Within the Goldstone Deep Space Communications Complex (DSCC), one of three tracking complexes in the NASA Deep Space Network, baselines of up to 21 km in length are available. Analysis of data from a series of short-baseline phase-delay interferometry experiments are presented to demonstrate the potential tracking accuracy on these baselines. Repeated differential observations of pairs of angularly close extragalactic radio sources were made to simulate differential spacecraft-quasar measurements. Fiber-optic data links and a correlation processor are currently being developed and installed at Goldstone for a demonstration of real-time CEI in 1990.

Mode-sum regularization of ⟨ϕ2⟩ in the angular-splitting method

NASA Astrophysics Data System (ADS)

Levi, Adam; Ori, Amos

2016-08-01

The computation of the renormalized stress-energy tensor or ⟨ϕ2⟩ren in curved spacetime is a challenging task, at both the conceptual and technical levels. Recently we developed a new approach to compute such renormalized quantities in asymptotically flat curved spacetimes, based on the point-splitting procedure. Our approach requires the spacetime to admit some symmetry. We already implemented this approach to compute ⟨ϕ2⟩ren in a stationary spacetime using t splitting, namely splitting in the time-translation direction. Here we present the angular-splitting version of this approach, aimed for computing renormalized quantities in a general (possibly dynamical) spherically symmetric spacetime. To illustrate how the angular-splitting method works, we use it here to compute ⟨ϕ2⟩ren for a quantum massless scalar field in Schwarzschild background, in various quantum states (Boulware, Unruh, and Hartle-Hawking states). We find excellent agreement with the results obtained from the t -splitting variant and also with other methods. Our main goal in pursuing this new mode-sum approach was to enable the computation of the renormalized stress-energy tensor in a dynamical spherically symmetric background, e.g. an evaporating black hole. The angular-splitting variant presented here is most suitable to this purpose.

The formation of high-mass binary star systems

NASA Astrophysics Data System (ADS)

Lund, Kristin; Bonnell, Ian A.

2018-06-01

We develop a semi-analytic model to investigate how accretion onto wide low-mass binary stars can result in a close high-mass binary system. The key ingredient is to allow mass accretion while limiting the gain in angular momentum. We envision this process as being regulated by an external magnetic field during infall. Molecular clouds are made to collapse spherically with material either accreting onto the stars or settling in a disk. Our aim is to determine what initial conditions are needed for the resulting binary to be both massive and close. Whether material accretes, and what happens to the binary separation as a result, depends on the relative size of its specific angular momentum, compared to the specific angular momentum of the binary. When we add a magnetic field we are introducing a torque to the system which is capable of stripping the molecular cloud of some of its angular momentum, and consequently easing the formation of high-mass binaries. Our results suggest that clouds in excess of 1000 M⊙ and radii of 0.5 pc or larger, can easily form binary systems with masses in excess of 25 M⊙ and separations of order 10 R⊙ with magnetic fields of order 100 μG (mass-to-flux ratios of order 5).

Angular selective window systems: Assessment of technical potential for energy savings

DOE PAGES

Fernandes, Luis L.; Lee, Eleanor S.; McNeil, Andrew; ...

2014-10-16

Static angular selective shading systems block direct sunlight and admit daylight within a specific range of incident solar angles. The objective of this study is to quantify their potential to reduce energy use and peak demand in commercial buildings using state-of-the art whole-building computer simulation software that allows accurate modeling of the behavior of optically-complex fenestration systems such as angular selective systems. Three commercial systems were evaluated: a micro-perforated screen, a tubular shading structure, and an expanded metal mesh. This evaluation was performed through computer simulation for multiple climates (Chicago, Illinois and Houston, Texas), window-to-wall ratios (0.15-0.60), building codes (ASHRAEmore » 90.1-2004 and 2010) and lighting control configurations (with and without). The modeling of the optical complexity of the systems took advantage of the development of state-of-the-art versions of the EnergyPlus, Radiance and Window simulation tools. Results show significant reductions in perimeter zone energy use; the best system reached 28% and 47% savings, respectively without and with daylighting controls (ASHRAE 90.1-2004, south facade, Chicago,WWR=0.45). As a result, angular selectivity and thermal conductance of the angle-selective layer, as well as spectral selectivity of low-emissivity coatings, were identified as factors with significant impact on performance.« less

Protein Structure Classification and Loop Modeling Using Multiple Ramachandran Distributions.

PubMed

Najibi, Seyed Morteza; Maadooliat, Mehdi; Zhou, Lan; Huang, Jianhua Z; Gao, Xin

2017-01-01

Recently, the study of protein structures using angular representations has attracted much attention among structural biologists. The main challenge is how to efficiently model the continuous conformational space of the protein structures based on the differences and similarities between different Ramachandran plots. Despite the presence of statistical methods for modeling angular data of proteins, there is still a substantial need for more sophisticated and faster statistical tools to model the large-scale circular datasets. To address this need, we have developed a nonparametric method for collective estimation of multiple bivariate density functions for a collection of populations of protein backbone angles. The proposed method takes into account the circular nature of the angular data using trigonometric spline which is more efficient compared to existing methods. This collective density estimation approach is widely applicable when there is a need to estimate multiple density functions from different populations with common features. Moreover, the coefficients of adaptive basis expansion for the fitted densities provide a low-dimensional representation that is useful for visualization, clustering, and classification of the densities. The proposed method provides a novel and unique perspective to two important and challenging problems in protein structure research: structure-based protein classification and angular-sampling-based protein loop structure prediction.

van der Waals torque and force between dielectrically anisotropic layered media.

PubMed

Lu, Bing-Sui; Podgornik, Rudolf

2016-07-28

We analyse van der Waals interactions between a pair of dielectrically anisotropic plane-layered media interacting across a dielectrically isotropic solvent medium. We develop a general formalism based on transfer matrices to investigate the van der Waals torque and force in the limit of weak birefringence and dielectric matching between the ordinary axes of the anisotropic layers and the solvent. We apply this formalism to study the following systems: (i) a pair of single anisotropic layers, (ii) a single anisotropic layer interacting with a multilayered slab consisting of alternating anisotropic and isotropic layers, and (iii) a pair of multilayered slabs each consisting of alternating anisotropic and isotropic layers, looking at the cases where the optic axes lie parallel and/or perpendicular to the plane of the layers. For the first case, the optic axes of the oppositely facing anisotropic layers of the two interacting slabs generally possess an angular mismatch, and within each multilayered slab the optic axes may either be the same or undergo constant angular increments across the anisotropic layers. In particular, we examine how the behaviors of the van der Waals torque and force can be "tuned" by adjusting the layer thicknesses, the relative angular increment within each slab, and the angular mismatch between the slabs.

Rapidly-Indexing Incremental-Angle Encoder

NASA Technical Reports Server (NTRS)

Christon, Philip R.; Meyer, Wallace W.

1989-01-01

Optoelectronic system measures relative angular position of shaft or other device to be turned, also measures absolute angular position after device turned through small angle. Relative angular position measured with fine resolution by optoelectronically counting finely- and uniformly-spaced light and dark areas on encoder disk as disk turns past position-sensing device. Also includes track containing coarsely- and nonuniformly-spaced light and dark areas, angular widths varying in proportion to absolute angular position. This second track provides gating and indexing signal.

The automotive application of discontinuously reinforced TiB-Ti composites

NASA Astrophysics Data System (ADS)

Saito, Takashi

2004-05-01

In 1998, Toyota Motor Corporation adopted intake valves and exhaust valves made of titanium-based alloys for the engine of its Altezza. Both valves were manufactured via a newly developed cost-effective powder metallurgy process. The exhaust valve is made of a newly developed titanium metal-matrix composite (MMC). The valve has achieved sufficient durability and reliability with a manufacturing cost acceptable for the mass-produced automobile engine components.

A model for mentoring newly-appointed nurse educators in nursing education institutions in South Africa.

PubMed

Seekoe, Eunice

2014-04-24

South Africa transformed higher education through the enactment of the Higher Education Act (No. 101 of 1997). The researcher identified the need to develop a model for the mentoring of newly-appointed nurse educators in nursing education institutions in South Africa.  To develop and describe the model for mentoring newly-appointed nurse educators in nursing education institutions in South Africa.  A qualitative and theory-generating design was used (following empirical findings regarding needs analysis) in order to develop the model. The conceptualisation of the framework focused on the context, content, process and the theoretical domains that influenced the model. Ideas from different theories were borrowed from and integrated with the literature and deductive and inductive strategies were applied.  The structure of the model is multidimensional and complex in nature (macro, mesoand micro) based on the philosophy of reflective practice, competency-based practice andcritical learning theories. The assumptions are in relation to stakeholders, context, mentoring, outcome, process and dynamic. The stakeholders are the mentor and mentee within an interactive participatory relationship. The mentoring takes place within the process with a sequence of activities such as relationship building, development, engagement, reflective process and assessment. Capacity building and empowerment are outcomes of mentoring driven by motivation.  The implication for nurse managers is that the model can be used to develop mentoring programmes for newly-appointed nurse educators.

Real-Time Condition Monitoring and Fault Diagnosis of Gear Train Systems Using Instantaneous Angular Speed (IAS) Analysis

NASA Astrophysics Data System (ADS)

Sait, Abdulrahman S.

This dissertation presents a reliable technique for monitoring the condition of rotating machinery by applying instantaneous angular speed (IAS) analysis. A new analysis of the effects of changes in the orientation of the line of action and the pressure angle of the resultant force acting on gear tooth profile of spur gear under different levels of tooth damage is utilized. The analysis and experimental work discussed in this dissertation provide a clear understating of the effects of damage on the IAS by analyzing the digital signals output of rotary incremental optical encoder. A comprehensive literature review of state of the knowledge in condition monitoring and fault diagnostics of rotating machinery, including gearbox system is presented. Progress and new developments over the past 30 years in failure detection techniques of rotating machinery including engines, bearings and gearboxes are thoroughly reviewed. This work is limited to the analysis of a gear train system with gear tooth surface faults utilizing angular motion analysis technique. Angular motion data were acquired using an incremental optical encoder. Results are compared to a vibration-based technique. The vibration data were acquired using an accelerometer. The signals were obtained and analyzed in the phase domains using signal averaging to determine the existence and position of faults on the gear train system. Forces between the mating teeth surfaces are analyzed and simulated to validate the influence of the presence of damage on the pressure angle and the IAS. National Instruments hardware is used and NI LabVIEW software code is developed for real-time, online condition monitoring systems and fault detection techniques. The sensitivity of optical encoders to gear fault detection techniques is experimentally investigated by applying IAS analysis under different gear damage levels and different operating conditions. A reliable methodology is developed for selecting appropriate testing/operating conditions of a rotating system to generate an alarm system for damage detection.

Biological and Host Range Studies with Bagous affinis, An Indian Weevil that Destroys Hydrilla Tubers. Aquatic Plant Control Research Program.

DTIC Science & Technology

1994-12-01

three times with newly emerged adults and three times with adults at least a month old. Treatments were (a) four hydrilla sprigs, (b) four hydrilla...Methods conducted to determine if feeding on nonhost plants stimulated the develop- ment of flight muscles. Newly emerged females were held in a plastic...Fecundity and adult longevity A fecundity and adult longevity test was conducted with newly emerged adults. Adults were held initially with moist paper

Maximum angular accuracy of pulsed laser radar in photocounting limit.

PubMed

Elbaum, M; Diament, P; King, M; Edelson, W

1977-07-01

To estimate the angular position of targets with pulsed laser radars, their images may be sensed with a fourquadrant noncoherent detector and the image photocounting distribution processed to obtain the angular estimates. The limits imposed on the accuracy of angular estimation by signal and background radiation shot noise, dark current noise, and target cross-section fluctuations are calculated. Maximum likelihood estimates of angular positions are derived for optically rough and specular targets and their performances compared with theoretical lower bounds.

Measures and models for angular correlation and angular-linear correlation. [correlation of random variables

NASA Technical Reports Server (NTRS)

Johnson, R. A.; Wehrly, T.

1976-01-01

Population models for dependence between two angular measurements and for dependence between an angular and a linear observation are proposed. The method of canonical correlations first leads to new population and sample measures of dependence in this latter situation. An example relating wind direction to the level of a pollutant is given. Next, applied to pairs of angular measurements, the method yields previously proposed sample measures in some special cases and a new sample measure in general.

A comparison of the efficacy of newly developed reversible inhibitors of acetylcholinesterase with commonly used pyridostigmine as pharmacological pre-treatment of soman-poisoned mice.

PubMed

Kassa, Jiri; Musilek, Kamil; Koomlova, Marketa; Bajgar, Jiri

2012-04-01

The ability of three newly developed reversible inhibitors of acetylcholinesterase (AChE) (K298, K344 and K474) and currently available carbamate pyridostigmine to increase the resistance of mice against soman and the efficacy of antidotal treatment of soman-poisoned mice was compared. Neither pyridostigmine nor new reversible inhibitors of AChE were able to increase the LD(50) value of soman. Thus, the pharmacological pre-treatment with pyridostigmine or newly synthesized inhibitors of AChE was not able to protect mice against soman-induced lethal acute toxicity. The pharmacological pre-treatment with pyridostigmine alone or with K474 was able to slightly increase the efficacy of antidotal treatment (the oxime HI-6 in combination with atropine) of soman-poisoned mice, but the increase in the efficacy of antidotal treatment was not significant. The other newly developed reversible inhibitors of AChF (K298, K344) were completely ineffective. These findings demonstrate that pharmacological pre-treatment of soman-poisoned mice with tested reversible inhibitors of AChF is not promising. © 2011 The Authors. Basic & Clinical Pharmacology & Toxicology © 2011 Nordic Pharmacological Society.

Motion fading is driven by perceived, not actual angular velocity.

PubMed

Kohler, P J; Caplovitz, G P; Hsieh, P-J; Sun, J; Tse, P U

2010-06-01

After prolonged viewing of a slowly drifting or rotating pattern under strict fixation, the pattern appears to slow down and then momentarily stop. Here we examine the relationship between such 'motion fading' and perceived angular velocity. Using several different dot patterns that generate emergent virtual contours, we demonstrate that whenever there is a difference in the perceived angular velocity of two patterns of dots that are in fact rotating at the same angular velocity, there is also a difference in the time to undergo motion fading for those two patterns. Conversely, whenever two patterns show no difference in perceived angular velocity, even if in fact rotating at different angular velocities, we find no difference in the time to undergo motion fading. Thus, motion fading is driven by the perceived rather than actual angular velocity of a rotating stimulus. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

PubMed Central

Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Kuncic, Zdenka; Keall, Paul J.

2014-01-01

Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR values were found to increase with decreasing RMSE values of projection angular gaps with strong correlations (r ≈ −0.7) regardless of the reconstruction algorithm used. Conclusions: Based on the authors’ results, displacement-based binning methods, better reconstruction algorithms, and the acquisition of even projection angular views are the most important factors to consider for improving thoracic 4D-CBCT image quality. In view of the practical issues with displacement-based binning and the fact that projection angular spacing is not currently directly controllable, development of better reconstruction algorithms represents the most effective strategy for improving image quality in thoracic 4D-CBCT for IGRT applications at the current stage. PMID:24694143

Developments for the 6He beta - nu angular correlation experiment

NASA Astrophysics Data System (ADS)

Zumwalt, David W.

This thesis describes developments toward the measurement of the angular correlation between the beta and the antineutrino in the beta decay of 6He. This decay is a pure Gamow-Teller decay which is described in the Standard Model as a purely axial vector weak interaction. The angular correlation is characterized by the parameter abetanu = -1/3 in the Standard Model. Any deviation from this value would be evidence for tensor components in the weak interaction and would constitute new physics. A new method will be used to measure the parameter a betanu from 6He decays, featuring a magneto-optical trap that will measure the beta particle in coincidence with the recoiling 6Li daughter ion. This neutral atom trapping scheme provides cold, tightly confined atoms which will reduce systematic uncertainties related to the initial position of the decay. By knowing the initial position of the decay and measuring the time of flight of the recoiling 6Li daughter ion in coincidence with the beta, the angular correlation between the beta and the antineutrino can be deduced. We aim to measure a betanu first to the level of 1%, and eventually to the 0.1% level, which would represent an order of magnitude improvement in precision over past experiments. Towards this goal, we have designed, built, and successfully tested a liquid lithium target to provide >2×10. {10} 6He atoms/sto a low-background environment, which is the most intense source of 6He presently available. This allowed for an additional measurement of the 6He half-life (806.89 +/- 0.11stat +0.23-0.19syst ms) to be made with unprecedented precision, resolving discrepancies in past measurements. We have also tested our trapping and detection apparatus and have begun to record preliminary coincidence events.

Variation in Angular Velocity and Angular Acceleration of a Particle in Rectilinear Motion

ERIC Educational Resources Information Center

Mashood, K. K.; Singh, V. A.

2012-01-01

We discuss the angular velocity ([image omitted]) and angular acceleration ([image omitted]) associated with a particle in rectilinear motion with constant acceleration. The discussion was motivated by an observation that students and even teachers have difficulty in ascribing rotational motion concepts to a particle when the trajectory is a…

47 CFR 73.128 - AM stereophonic broadcasting.

Code of Federal Regulations, 2014 CFR

2014-10-01

... magnitude of the nth term of the difference signal ωsn=the nth order angular velocity of the sum signal ωdn=the nth order angular velocity of the difference signal ωc=the angular velocity of the carrier... presence of envelope modulation. (5) Maximum angular modulation, which occurs on negative peaks of the left...

System and method for correcting attitude estimation

NASA Technical Reports Server (NTRS)

Josselson, Robert H. (Inventor)

2010-01-01

A system includes an angular rate sensor disposed in a vehicle for providing angular rates of the vehicle, and an instrument disposed in the vehicle for providing line-of-sight control with respect to a line-of-sight reference. The instrument includes an integrator which is configured to integrate the angular rates of the vehicle to form non-compensated attitudes. Also included is a compensator coupled across the integrator, in a feed-forward loop, for receiving the angular rates of the vehicle and outputting compensated angular rates of the vehicle. A summer combines the non-compensated attitudes and the compensated angular rates of the to vehicle to form estimated vehicle attitudes for controlling the instrument with respect to the line-of-sight reference. The compensator is configured to provide error compensation to the instrument free-of any feedback loop that uses an error signal. The compensator may include a transfer function providing a fixed gain to the received angular rates of the vehicle. The compensator may, alternatively, include a is transfer function providing a variable gain as a function of frequency to operate on the received angular rates of the vehicle.

Energy Weighted Angular Correlations Between Hadrons Produced in Electron-Positron Annihilation.

NASA Astrophysics Data System (ADS)

Strharsky, Roger Joseph

Electron-positron annihilation at large center of mass energy produces many hadronic particles. Experimentalists then measure the energies of these particles in calorimeters. This study investigated correlations between the angular locations of one or two such calorimeters and the angular orientation of the electron beam in the laboratory frame of reference. The calculation of these correlations includes weighting by the fraction of the total center of mass energy which the calorimeter measures. Starting with the assumption that the reaction proceeeds through the intermediate production of a single quark/anti-quark pair, a simple statistical model was developed to provide a phenomenological description of the distribution of final state hadrons. The model distributions were then used to calculate the one- and two-calorimeter correlation functions. Results of these calculations were compared with available data and several predictions were made for those quantities which had not yet been measured. Failure of the model to reproduce all of the data was discussed in terms of quantum chromodynamics, a fundamental theory which includes quark interactions.

Quantum entanglement of angular momentum states with quantum numbers up to 10,010

PubMed Central

Fickler, Robert; Campbell, Geoff; Buchler, Ben; Lam, Ping Koy; Zeilinger, Anton

2016-01-01

Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors, to generate photons with more than 10,000 quanta of OAM. Moreover, we demonstrate quantum entanglement between these large OAM quanta of one photon and the polarization of its partner photon. To our knowledge, this corresponds to entanglement with the largest quantum number that has been demonstrated in an experiment. The results may also open novel ways to couple single photons to massive objects, enhance angular resolution, and highlight OAM as a promising way to increase the information capacity of a single photon. PMID:27856742

Chaotic gas turbine subject to augmented Lorenz equations.

PubMed

Cho, Kenichiro; Miyano, Takaya; Toriyama, Toshiyuki

2012-09-01

Inspired by the chaotic waterwheel invented by Malkus and Howard about 40 years ago, we have developed a gas turbine that randomly switches the sense of rotation between clockwise and counterclockwise. The nondimensionalized expressions for the equations of motion of our turbine are represented as a starlike network of many Lorenz subsystems sharing the angular velocity of the turbine rotor as the central node, referred to as augmented Lorenz equations. We show qualitative similarities between the statistical properties of the angular velocity of the turbine rotor and the velocity field of large-scale wind in turbulent Rayleigh-Bénard convection reported by Sreenivasan et al. [Phys. Rev. E 65, 056306 (2002)]. Our equations of motion achieve the random reversal of the turbine rotor through the stochastic resonance of the angular velocity in a double-well potential and the force applied by rapidly oscillating fields. These results suggest that the augmented Lorenz model is applicable as a dynamical model for the random reversal of turbulent large-scale wind through cessation.

Quantum entanglement of angular momentum states with quantum numbers up to 10,010

NASA Astrophysics Data System (ADS)

Fickler, Robert; Campbell, Geoff; Buchler, Ben; Lam, Ping Koy; Zeilinger, Anton

2016-11-01

Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors, to generate photons with more than 10,000 quanta of OAM. Moreover, we demonstrate quantum entanglement between these large OAM quanta of one photon and the polarization of its partner photon. To our knowledge, this corresponds to entanglement with the largest quantum number that has been demonstrated in an experiment. The results may also open novel ways to couple single photons to massive objects, enhance angular resolution, and highlight OAM as a promising way to increase the information capacity of a single photon.

Extraction of urban vegetation with Pleiades multiangular images

NASA Astrophysics Data System (ADS)

Lefebvre, Antoine; Nabucet, Jean; Corpetti, Thomas; Courty, Nicolas; Hubert-Moy, Laurence

2016-10-01

Vegetation is essential in urban environments since it provides significant services in terms of health, heat, property value, ecology ... As part of the European Union Biodiversity Strategy Plan for 2020, the protection and development of green-infrastructures is strengthened in urban areas. In order to evaluate and monitor the quality of the green infra-structures, this article investigates contributions of Pléiades multi-angular images to extract and characterize low and high urban vegetation. From such images one can extract both spectral and elevation information from optical images. Our method is composed of 3 main steps : (1) the computation of a normalized Digital Surface Model from the multi-angular images ; (2) Extraction of spectral and contextual features ; (3) a classification of vegetation classes (tree and grass) performed with a random forest classifier. Results performed in the city of Rennes in France show the ability of multi-angular images to extract DEM in urban area despite building height. It also highlights its importance and its complementarity with contextual information to extract urban vegetation.

Generalization of helicoidal beams for short pulses.

PubMed

Thomas, Jean-Louis; Brunet, Thomas; Coulouvrat, François

2010-01-01

A generalization to the transient regime is developed for waves with a phase singularity of the screw type. These singular waves are commonly called vortices for all kind of waves as, for instance, optical vortex or acoustical vortex. We generalize the definition of vortices to get an azimuthal velocity invariant for all the frequency components contained in the broad spectrum of a short pulse. This generalization leads to a modification of the orbital angular momentum definition. Another generalization is introduced by considering helicoidal waves with a finite number of turns. We demonstrate that, in this last case, the topological charge is no longer an integer. This provides a physical interpretation to vortices of fractional charge that are involved here to take into account the diffraction occurring at both tips of the now finite helical wave front. We show that shortening the pulse implies an angular localization of the wave energy and, as a consequence, a spreading of the angular momentum amplitude due to the uncertainty principle.

Quantum entanglement of angular momentum states with quantum numbers up to 10,010.

PubMed

Fickler, Robert; Campbell, Geoff; Buchler, Ben; Lam, Ping Koy; Zeilinger, Anton

2016-11-29

Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors, to generate photons with more than 10,000 quanta of OAM. Moreover, we demonstrate quantum entanglement between these large OAM quanta of one photon and the polarization of its partner photon. To our knowledge, this corresponds to entanglement with the largest quantum number that has been demonstrated in an experiment. The results may also open novel ways to couple single photons to massive objects, enhance angular resolution, and highlight OAM as a promising way to increase the information capacity of a single photon.

A new multidimensional diagnostic method for measuring the properties of intense ion beams

NASA Astrophysics Data System (ADS)

Yasuike, Kazuhito; Miyamoto, Shuji; Nakai, Sadao

1996-02-01

A new arrayed pinhole camera (APC) diagnostic method for intense ion beams has been developed. The APC diagnostic technique permits the acquisition of the angular divergences and the ion fluxes of high intensity ion beams, in one shot, with a spatial resolution on the source of better than 1 mm and an effective angular divergence resolution of better than 10 mrad. A prototype time integrated APC has been designed and evaluated. The demonstration experiments have been performed on a Reiden-IV, 1 MV and 1 Ω pulsed power machine [1 T W (tera-watt or trillion watts)]. Proton beams of 0.7 MeV, with a pulse duration of ˜50 ns and an ion current density of about 100 A/cm2, were generated in an applied-Br type ion diode source using paraffin-filled grooves. These experimental results show that the APC can measure nonuniformities in the ion beam intensity generated from the ion source and the dependence of beam angular divergence on ion beam intensity.

A Compact Inductive Position Sensor Made by Inkjet Printing Technology on a Flexible Substrate

PubMed Central

Jeranče, Nikola; Vasiljević, Dragana; Samardžić, Nataša; Stojanović, Goran

2012-01-01

This paper describes the design, simulation and fabrication of an inductive angular position sensor on a flexible substrate. The sensor is composed of meandering silver coils printed on a flexible substrate (Kapton film) using inkjet technology. The flexibility enables that after printing in the plane, the coils could be rolled and put inside each other. By changing the angular position of the internal coil (rotor) related to the external one (stator), the mutual inductance is changed and consequently the impedance. It is possible to determine the angular position from the measured real and imaginary part of the impedance, in our case in the frequency range from 1 MHz to 10 MHz. Experimental results were compared with simulation results obtained by in-house developed software tool, and very good agreement has been achieved. Thanks to the simple design and fabrication, smaller package space requirements and weight, the presented sensor represents a cost-effective alternative to the other sensors currently used in series production applications. PMID:22438710

An angle encoder for super-high resolution and super-high accuracy using SelfA

NASA Astrophysics Data System (ADS)

Watanabe, Tsukasa; Kon, Masahito; Nabeshima, Nobuo; Taniguchi, Kayoko

2014-06-01

Angular measurement technology at high resolution for applications such as in hard disk drive manufacturing machines, precision measurement equipment and aspherical process machines requires a rotary encoder with high accuracy, high resolution and high response speed. However, a rotary encoder has angular deviation factors during operation due to scale error or installation error. It has been assumed to be impossible to achieve accuracy below 0.1″ in angular measurement or control after the installation onto the rotating axis. Self-calibration (Lu and Trumper 2007 CIRP Ann. 56 499; Kim et al 2011 Proc. MacroScale; Probst 2008 Meas. Sci. Technol. 19 015101; Probst et al Meas. Sci. Technol. 9 1059; Tadashi and Makoto 1993 J. Robot. Mechatronics 5 448; Ralf et al 2006 Meas. Sci. Technol. 17 2811) and cross-calibration (Probst et al 1998 Meas. Sci. Technol. 9 1059; Just et al 2009 Precis. Eng. 33 530; Burnashev 2013 Quantum Electron. 43 130) technologies for a rotary encoder have been actively discussed on the basis of the principle of circular closure. This discussion prompted the development of rotary tables which achieve reliable and high accuracy angular verification. We apply these technologies for the development of a rotary encoder not only to meet the requirement of super-high accuracy but also to meet that of super-high resolution. This paper presents the development of an encoder with 221 = 2097 152 resolutions per rotation (360°), that is, corresponding to a 0.62″ signal period, achieved by the combination of a laser rotary encoder supplied by Magnescale Co., Ltd and a self-calibratable encoder (SelfA) supplied by The National Institute of Advanced Industrial Science & Technology (AIST). In addition, this paper introduces the development of a rotary encoder to guarantee ±0.03″ accuracy at any point of the interpolated signal, with respect to the encoder at the minimum resolution of 233, that is, corresponding to a 0.0015″ signal period after interpolation of 212 (= 4096) divisions through the interpolator.

The effects of obesity on balance recovery using an ankle strategy.

PubMed

Matrangola, Sara L; Madigan, Michael L

2011-06-01

Obesity is associated with an increased risk of falls. The purpose of this study was to investigate the effects of obesity on balance recovery using an ankle strategy. In addition, computer simulations to understand how increased inertia and weight associated with obesity independently influence balance recovery. Ten normal weight (BMI: 22.7±0.6 kg/m(2)) and ten obese (BMI: 32.2±2.2 kg/m(2)) adult male subjects participated in the study. Subjects recovered balance using an ankle strategy after three types of postural perturbations: an initial angular displacement, an initial angular velocity from the natural stance, and an initial angular velocity from a prescribed position. Balance recovery was quantified by the largest initial angular displacement or angular velocity from which balance could be recovered. Obesity impaired balance recovery from perturbations involving an initial angular velocity, but not from an initial angular displacement. Similarly, computer simulations determined that increased inertia is beneficial to balance recovery when there is little to no initial angular velocity. These findings indicate that the effects of obesity on balance recovery are dependent on the type of perturbation, and that increased inertia associated with obesity can be beneficial for perturbations that involve little to no initial angular velocity. Copyright © 2011 Elsevier B.V. All rights reserved.

Generation of vertical angular momentum in single, double, and triple-turn pirouette en dehors in ballet.

PubMed

Kim, Jemin; Wilson, Margaret A; Singhal, Kunal; Gamblin, Sarah; Suh, Cha-Young; Kwon, Young-Hoo

2014-09-01

The purpose of this study was to investigate the vertical angular momentum generation strategies used by skilled ballet dancers in pirouette en dehors. Select kinematic parameters of the pirouette preparation (stance depth, vertical center-of-mass motion range, initial shoulder line position, shoulder line angular displacement, and maximum trunk twist angle) along with vertical angular momentum parameters during the turn (maximum momentums of the whole body and body parts, and duration and rate of generation) were obtained from nine skilled collegiate ballet dancers through a three-dimensional motion analysis and compared among three turn conditions (single, double, and triple). A one-way ('turn') multivariate analysis of variance of the kinematic parameters and angular momentum parameters of the whole body and a two-way analysis of variance ('turn' × 'body') of the maximum angular momentums of the body parts were conducted. Significant 'turn' effects were observed in the kinematic/angular momentum parameters (both the preparation and the turn) (p <  0.05). As the number of turns increased, skilled dancers generated larger vertical angular momentums by predominantly increasing the rate of momentum generation using rotation of the upper trunk and arms. The trail (closing) arm showed the largest contribution to whole-body angular momentum followed by the lead arm.

Development of methods and specifications for the use of inertial profilers and the international roughness index for newly constructed pavement.

DOT National Transportation Integrated Search

2013-06-01

The Indiana Department of Transportation (INDOT) is currently utilizing a profilograph and the profile index for measuring smoothness : assurance for newly constructed pavements. However, there are benefits to implementing a new IRI based smoothness ...

Massive star formation by accretion. II. Rotation: how to circumvent the angular momentum barrier?

NASA Astrophysics Data System (ADS)

Haemmerlé, L.; Eggenberger, P.; Meynet, G.; Maeder, A.; Charbonnel, C.; Klessen, R. S.

2017-06-01

Context. Rotation plays a key role in the star-formation process, from pre-stellar cores to pre-main-sequence (PMS) objects. Understanding the formation of massive stars requires taking into account the accretion of angular momentum during their PMS phase. Aims: We study the PMS evolution of objects destined to become massive stars by accretion, focusing on the links between the physical conditions of the environment and the rotational properties of young stars. In particular, we look at the physical conditions that allow the production of massive stars by accretion. Methods: We present PMS models computed with a new version of the Geneva Stellar Evolution code self-consistently including accretion and rotation according to various accretion scenarios for mass and angular momentum. We describe the internal distribution of angular momentum in PMS stars accreting at high rates and we show how the various physical conditions impact their internal structures, evolutionary tracks, and rotation velocities during the PMS and the early main sequence. Results: We find that the smooth angular momentum accretion considered in previous studies leads to an angular momentum barrier and does not allow the formation of massive stars by accretion. A braking mechanism is needed in order to circumvent this angular momentum barrier. This mechanism has to be efficient enough to remove more than two thirds of the angular momentum from the inner accretion disc. Due to the weak efficiency of angular momentum transport by shear instability and meridional circulation during the accretion phase, the internal rotation profiles of accreting stars reflect essentially the angular momentum accretion history. As a consequence, careful choice of the angular momentum accretion history allows circumvention of any limitation in mass and velocity, and production of stars of any mass and velocity compatible with structure equations.

Characterization of thigh and shank segment angular velocity during jump landing tasks commonly used to evaluate risk for ACL injury.

PubMed

Dowling, Ariel V; Favre, Julien; Andriacchi, Thomas P

2012-09-01

The dynamic movements associated with anterior cruciate ligament (ACL) injury during jump landing suggest that limb segment angular velocity can provide important information for understanding the conditions that lead to an injury. Angular velocity measures could provide a quick and simple method of assessing injury risk without the constraints of a laboratory. The objective of this study was to assess the inter-subject variations and the sensitivity of the thigh and shank segment angular velocity in order to determine if these measures could be used to characterize jump landing mechanisms. Additionally, this study tested the correlation between angular velocity and the knee abduction moment. Thirty-six healthy participants (18 male) performed drop jumps with bilateral and unilateral landing. Thigh and shank angular velocities were measured by a wearable inertial-based system, and external knee moments were measured using a marker-based system. Discrete parameters were extracted from the data and compared between systems. For both jumping tasks, the angular velocity curves were well defined movement patterns with high inter-subject similarity in the sagittal plane and moderate to good similarity in the coronal and transverse planes. The angular velocity parameters were also able to detect differences between the two jumping tasks that were consistent across subjects. Furthermore, the coronal angular velocities were significantly correlated with the knee abduction moment (R of 0.28-0.51), which is a strong indicator of ACL injury risk. This study suggested that the thigh and shank angular velocities, which describe the angular dynamics of the movement, should be considered in future studies about ACL injury mechanisms.

Professional socialization: the key to survival as a newly qualified nurse.

PubMed

Mooney, Mary

2007-04-01

The impact and prevalence of professional socialization in nursing has been written about extensively. Despite the many positive developments that have taken place in nursing within the past decade, the role of professional socialization remains heavily weighted and is of particular significance to those nurses who are newly qualified. The account given by newly registered nurses in this study demonstrates that their ability and willingness to become professionally socialized determines their ease of survival at clinical level. Twelve newly qualified Irish nurses, from two separate cohorts, were interviewed to ascertain their perceptions of becoming newly qualified nurses. A grounded theory approach was used and data were analysed using thematic analysis. A category that emerged was linked very strongly with professional socialization. The respondents did not refer to professional socialization per se, but through the coding process this emerged as the linchpin of the discussion.

Clinical Prediction Model for Time in Therapeutic Range While on Warfarin in Newly Diagnosed Atrial Fibrillation.

PubMed

Williams, Brent A; Evans, Michael A; Honushefsky, Ashley M; Berger, Peter B

2017-10-12

Though warfarin has historically been the primary oral anticoagulant for stroke prevention in newly diagnosed atrial fibrillation (AF), several new direct oral anticoagulants may be preferred when anticoagulation control with warfarin is expected to be poor. This study developed a prediction model for time in therapeutic range (TTR) among newly diagnosed AF patients on newly initiated warfarin as a tool to assist decision making between warfarin and direct oral anticoagulants. This electronic medical record-based, retrospective study included newly diagnosed, nonvalvular AF patients with no recent warfarin exposure receiving primary care services through a large healthcare system in rural Pennsylvania. TTR was estimated as the percentage of time international normalized ratio measurements were between 2.0 and 3.0 during the first year following warfarin initiation. Candidate predictors of TTR were chosen from data elements collected during usual clinical care. A TTR prediction model was developed and temporally validated and its predictive performance was compared with the SAMe-TT 2 R 2 score (sex, age, medical history, treatment, tobacco, race) using R 2 and c-statistics. A total of 7877 newly diagnosed AF patients met study inclusion criteria. Median (interquartile range) TTR within the first year of starting warfarin was 51% (32, 67). Of 85 candidate predictors evaluated, 15 were included in the final validated model with an R 2 of 15.4%. The proposed model showed better predictive performance than the SAMe-TT 2 R 2 score ( R 2 =3.0%). The proposed prediction model may assist decision making on the proper mode of oral anticoagulant among newly diagnosed AF patients. However, predicting TTR on warfarin remains challenging. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

A comparison of three approaches for simulating fine-scale surface winds in support of wildland fire management: Part I. Model formulation and comparison against measurements

Treesearch

Jason M. Forthofer; Bret W. Butler; Natalie S. Wagenbrenner

2014-01-01

For this study three types of wind models have been defined for simulating surface wind flow in support of wildland fire management: (1) a uniform wind field (typically acquired from coarse-resolution (,4 km) weather service forecast models); (2) a newly developed mass-conserving model and (3) a newly developed mass and momentumconserving model (referred to as the...

Psychological characteristics of patients with newly developed psychogenic seizures

PubMed Central

van Merode, T; Twellaar, M; Kotsopoulos, I; Kessels, A; Merckelbach, H; de Krom, M C T F M; Knottnerus, J

2004-01-01

Methods: Using validated scales, 178 patients from the general population diagnosed with newly developed seizures were assessed, at a point in time when the nature of their seizures was yet unknown to either doctors or patients. After standardised neurological examination, 138 patients were diagnosed with non-psychogenic seizures (NPS), while 40 patients were found to have psychogenic seizures (PS). To evaluate possible differences between the genders and the diagnostic groups, univariate analyses of variance were done. Results: PS patients reported significantly more comorbid psychopathological complaints, dissociative experiences, anxiety, and self-reported childhood trauma than NPS patients. In addition, PS patients had lower quality of life ratings than NPS patients. These effects were not modulated by gender. Conclusions: The results of the present study indicate that patients with newly developed PS constitute a group with complex psychopathological features that warrant early detection and treatment. PMID:15258225

Development of a sliding mode control model for quiet upright stance.

PubMed

Zhang, Hongbo; Nussbaum, Maury A; Agnew, Michael J

2016-02-01

Human upright stance appears maintained or controlled intermittently, through some combination of passive and active ankle torques, respectively representing intrinsic and contractile contributions of the ankle musculature. Several intermittent postural control models have been proposed, though it has been challenging to accurately represent actual kinematics and kinetics and to separately estimate passive and active ankle torque components. Here, a simplified single-segment, 2D (sagittal plane) sliding mode control model was developed for application to track kinematics and kinetics during upright stance. The model was implemented and evaluated using previous experimental data consisting of whole body angular kinematics and ankle torques. Tracking errors for the whole-body center-of-mass (COM) angle and angular velocity, as well as ankle torque, were all within ∼10% of experimental values, though tracking performance for COM angular acceleration was substantially poorer. The model also enabled separate estimates of the contributions of passive and active ankle torques, with overall contributions estimated here to be 96% and 4% of the total ankle torque, respectively. Such a model may have future utility in understanding human postural control, though additional work is needed, such as expanding the model to multiple segments and to three dimensions. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

SPICA, Stellar Parameters and Images with a Cophased Array: a 6T visible combiner for the CHARA array.

PubMed

Mourard, Denis; Bério, Philippe; Perraut, Karine; Clausse, Jean-Michel; Creevey, Orlagh; Martinod, Marc-Antoine; Meilland, Anthony; Millour, Florentin; Nardetto, Nicolas

2017-05-01

High angular resolution studies of stars in the optical domain have highly progressed in recent years. After the results obtained with the visible instrument Visible spEctroGraph and polArimeter (VEGA) on the Center for High Angular Resolution Astronomy (CHARA) array and the recent developments on adaptive optics and fibered interferometry, we have started the design and study of a new six-telescope visible combiner with single-mode fibers. It is designed as a low spectral resolution instrument for the measurement of the angular diameter of stars to make a major step forward in terms of magnitude and precision with respect to the present situation. For a large sample of bright stars, a medium spectral resolution mode will allow unprecedented spectral imaging of stellar surfaces and environments for higher accuracy on stellar/planetary parameters. To reach the ultimate performance of the instrument in terms of limiting magnitude (Rmag≃8 for diameter measurements and Rmag≃4 to 5 for imaging), Stellar Parameters and Images with a Cophased Array (SPICA) includes the development of a dedicated fringe tracking system in the H band to reach "long" (200 ms to 30 s) exposures of the fringe signal in the visible.

A multi-method approach to curriculum development for in-service training in China's newly established health emergency response offices.

PubMed

Wang, Yadong; Li, Xiangrui; Yuan, Yiwen; Patel, Mahomed S

2014-01-01

To describe an innovative approach for developing and implementing an in-service curriculum in China for staff of the newly established health emergency response offices (HEROs), and that is generalisable to other settings. The multi-method training needs assessment included reviews of the competency domains needed to implement the International Health Regulations (2005) as well as China's policies and emergency regulations. The review, iterative interviews and workshops with experts in government, academia, the military, and with HERO staff were reviewed critically by an expert technical advisory panel. Over 1600 participants contributed to curriculum development. Of the 18 competency domains identified as essential for HERO staff, nine were developed into priority in-service training modules to be conducted over 2.5 weeks. Experts from academia and experienced practitioners prepared and delivered each module through lectures followed by interactive problem-solving exercises and desktop simulations to help trainees apply, experiment with, and consolidate newly acquired knowledge and skills. This study adds to the emerging literature on China's enduring efforts to strengthen its emergency response capabilities since the outbreak of SARS in 2003. The multi-method approach to curriculum development in partnership with senior policy-makers, researchers, and experienced practitioners can be applied in other settings to ensure training is responsive and customized to local needs, resources and priorities. Ongoing curriculum development should reflect international standards and be coupled with the development of appropriate performance support systems at the workplace for motivating staff to apply their newly acquired knowledge and skills effectively and creatively.

Singularity in the Laboratory Frame Angular Distribution Derived in Two-Body Scattering Theory

ERIC Educational Resources Information Center

Dick, Frank; Norbury, John W.

2009-01-01

The laboratory (lab) frame angular distribution derived in two-body scattering theory exhibits a singularity at the maximum lab scattering angle. The singularity appears in the kinematic factor that transforms the centre of momentum (cm) angular distribution to the lab angular distribution. We show that it is caused in the transformation by the…

Stellar Rotation on the Main Sequence

NASA Astrophysics Data System (ADS)

Soderblom, D.; Murdin, P.

2000-11-01

The conservation of ANGULAR MOMENTUM is the one effective counterbalance to the inexorable pull of gravity in the universe, and so everything rotates. Stars acquire their angular momentum when they form, and, indeed, the manner in which nearly all this initial angular momentum is dissipated remains poorly understood, but without substantial angular momentum loss an interstellar cloud could never ...

Spin-to-orbit conversion at acousto-optic diffraction of light: conservation of optical angular momentum.

PubMed

Skab, Ihor; Vlokh, Rostyslav

2012-04-01

Acousto-optic diffraction of light in optically active cubic crystals is analyzed from the viewpoint of conservation of optical angular momentum. It is shown that the availability of angular momentum in the diffracted optical beam can be necessarily inferred from the requirements of angular momentum conservation law. As follows from our analysis, a circularly polarized diffracted wave should bear an orbital angular momentum. The efficiency of the spin-to-orbit momentum conversion is governed by the efficiency of acousto-optic diffraction.

Angular behavior of synchrotron radiation harmonics.

PubMed

Bagrov, V G; Bulenok, V G; Gitman, D M; Jara, Jose Acosta; Tlyachev, V B; Jarovoi, A T

2004-04-01

The detailed analysis of angular dependence of the synchrotron radiation (SR) is presented. Angular distributions of linear and circular polarization integrated over all harmonics, well known for relativistic electron energies, are extended to include radiation from electrons that are not fully relativistic. In particular, we analyze the angular dependence of the integral SR intensity and peculiarities of the angular dependence of the first harmonics SR. Studying spectral SR intensities, we have discovered their unexpected angular behavior, completely different from that of the integral SR intensity; namely, for any given synchrotron frequency, maxima of the spectral SR intensities recede from the orbit plane with increasing particle energy. Thus, in contrast with the integral SR intensity, the spectral ones have the tendency to deconcentrate themselves on the orbit plane.

There are many ways to spin a photon: Half-quantization of a total optical angular momentum

PubMed Central

Ballantine, Kyle E.; Donegan, John F.; Eastham, Paul R.

2016-01-01

The angular momentum of light plays an important role in many areas, from optical trapping to quantum information. In the usual three-dimensional setting, the angular momentum quantum numbers of the photon are integers, in units of the Planck constant ħ. We show that, in reduced dimensions, photons can have a half-integer total angular momentum. We identify a new form of total angular momentum, carried by beams of light, comprising an unequal mixture of spin and orbital contributions. We demonstrate the half-integer quantization of this total angular momentum using noise measurements. We conclude that for light, as is known for electrons, reduced dimensionality allows new forms of quantization. PMID:28861467

Physical angular momentum separation for QED

NASA Astrophysics Data System (ADS)

Sun, Weimin

2017-04-01

We study the non-uniqueness problem of the gauge-invariant angular momentum separation for the case of QED, which stems from the recent controversy concerning the proper definitions of the orbital angular momentum and spin operator of the individual parts of a gauge field system. For the free quantum electrodynamics without matter, we show that the basic requirement of Euclidean symmetry selects a unique physical angular momentum separation scheme from the multitude of the possible angular momentum separation schemes constructed using the various gauge-invariant extensions (GIEs). Based on these results, we propose a set of natural angular momentum separation schemes for the case of interacting QED by invoking the formalism of asymptotic fields. Some perspectives on such a problem for the case of QCD are briefly discussed.

How Can Online Discussion Support and Develop Newly Qualified Teachers? Research Briefing No. 51

ERIC Educational Resources Information Center

Unwin, Adam

2013-01-01

This research investigated newly qualified teachers (NQTs) experiences of participating in online discussions (ODs) that were part of their Master of Teaching (MTeach) course. [The project was partially funded by the Excellence in Work-Based Learning for Education Professionals (WLE) Centre in 2009.

Implementing a Low-Cost Long-Range Unmanned Underwater Vehicle: The SeaDiver Glider

DTIC Science & Technology

2007-01-09

25 2. Position estimation.............................................................................26 3. Angular ...calculation velocity..............................................................27 4. Angular calculation position...25 Figure 14. Angular Positions.............................................................................................27

Development of ultrahigh-resolution inelastic x-ray scattering optics

NASA Astrophysics Data System (ADS)

Huang, Xian-Rong; Zhong, Zhong; Cai, Yong Q.; Coburn, S.

2008-08-01

One of the major goals of the National Synchrotron Light Source II project is to achieve ultrahigh energy resolution up to 0.1 meV for medium-energy inelastic X-ray scattering spectroscopy based on the angular dispersion optics employing extremely asymmetric backscattering geometry. In this papaer, we describe the complete monochromatization mechanisms underlying the new optics. We have also designed and tested a CDW-CDW prototype under ambient condition, with which we have successfully demonstrated the important angular dispersion effect, the Borrman enhanced transmission effect, and other optical principles involved in every step of the entire diffraction process, and found good agreement with the theoretical expectations. These studies indicate that the new optics are feasible in principle but face some technical challenges that need to be solved by our future systematic research and development activities before their practical applications.

Functional form for plasma velocity in a rapidly rotating tokamak discharge

DOE PAGES

Burrell, Keith H.; Chrystal, C. olin

2014-07-25

A recently developed technique using charge exchange spectroscopy determines the ion poloidal rotation in tokamak plasmas from the poloidal variation in the toroidal angular rotation speed. The basis for this technique is the functional form for the plasma velocity calculated from the equilibrium equations. The initial development of this technique utilized the functional form determined for conditions where the ion toroidal rotation speed is much smaller than the ion thermal speed. There are cases, however, where the toroidal rotation can be comparable to the ion thermal speed, especially for high atomic number impurities. Furthermore, the present paper extends the previousmore » analysis to this high rotation speed case and demonstrates how to extract the poloidal rotation speed from measurements of the toroidal angular rotation speed at two points on a flux surface.« less

Neutron Angular Scatter Effects in 3DHZETRN: Quasi-Elastic

NASA Technical Reports Server (NTRS)

Wilson, John W.; Werneth, Charles M.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

2017-01-01

The current 3DHZETRN code has a detailed three dimensional (3D) treatment of neutron transport based on a forward/isotropic assumption and has been compared to Monte Carlo (MC) simulation codes in various geometries. In most cases, it has been found that 3DHZETRN agrees with the MC codes to the extent they agree with each other. However, a recent study of neutron leakage from finite geometries revealed that further improvements to the 3DHZETRN formalism are needed. In the present report, angular scattering corrections to the neutron fluence are provided in an attempt to improve fluence estimates from a uniform sphere. It is found that further developments in the nuclear production models are required to fully evaluate the impact of transport model updates. A model for the quasi-elastic neutron production spectra is therefore developed and implemented into 3DHZETRN.

Modeling of functional trunk muscle performance: interfacing ergonomics and spine rehabilitation in response to the ADA.

PubMed

Khalaf, K A; Parnianpour, M; Sparto, P J; Simon, S R

1997-10-01

The combination of increasing costs of musculoskeletal injuries and the implementation of the Americans with Disabilities Act (ADA) has created the need for a more objective functional understanding of dynamic trunk performance. In this study, trunk extensor and flexor strengths were measured as a function of angular position and velocity for 20 subjects performing maximum isometric and isokinetic exertions. Results indicate that trunk strength is significantly influenced by trunk angular position, trunk angular velocity, gender, and direction, as well as by the interaction between trunk angular position and velocity. Three-dimensional surfaces of trunk strength in response to trunk angular position and velocity were constructed for each subject per direction. Such data presentation is more accurate and gives better insight about the strength profile of an individual than does the traditional use of a single strength value. The joint strength capacity profiles may be combined with joint torque requirements from a manual material handling task, such as a lifting task, to compute the dynamic utilization ratio for the trunk muscles. This ratio can be used as a unified measure of both task demand and functional capacity to guide job assignment, return to work, and prognosis during the rehabilitation processes. Furthermore, the strength regressions developed in this study would provide dynamic strength limits that can be used as functional constraints in the computer simulation of physical activities, such as lifting. In light of the ADA, this would be of great value in predicting the consequences of task modifications and/or workstation alterations without subjecting an injured worker or an individual with a disability to unnecessary testing.

Assessing the Impact of Observations on the Prediction of Effective Atmospheric Angular Momentum from NAVGEM

NASA Astrophysics Data System (ADS)

Baker, N. L.; Langland, R.

2016-12-01

Variations in Earth rotation are measured by comparing a time based on Earth's variable rotation rate about its axis to a time standard based on an internationally coordinated ensemble of atomic clocks that provide a uniform time scale. The variability of Earth's rotation is partly due to the changes in angular momentum that occur in the atmosphere and ocean as weather patterns and ocean features develop, propagate, and dissipate. The NAVGEM Effective Atmospheric Angular Momentum Functions (EAAMF) and their predictions are computed following Barnes et al. (1983), and provided to the U.S. Naval Observatory daily. These along with similar data from the NOAA GFS model are used to calculate and predict the Earth orientation parameters (Stamatakos et al., 2016). The Navy's high-resolution global weather prediction system consists of the Navy Global Environmental Model (NAVGEM; Hogan et al., 2014) and a hybrid four-dimensional variational data assimilation system (4DVar) (Kuhl et al., 2013). An important component of NAVGEM is the Forecast Sensitivity Observation Impact (FSOI). FSOI is a mathematical method to quantify the contribution of individual observations or sets of observations to the reduction in the 24-hr forecast error (Langland and Baker, 2004). The FSOI allows for dynamic monitoring of the relative quality and value of the observations assimilated by NAVGEM, and the relative ability of the data assimilation system to effectively use the observation information to generate an improved forecast. For this study, along with the FSOI based on the global moist energy error norm, we computed the FSOI using an error norm based on the Effective Angular Momentum Functions. This modification allowed us to assess which observations were most beneficial in reducing the 24-hr forecast error for the atmospheric angular momentum.

Angular momentum properties of haloes and their baryon content in the Illustris simulation

NASA Astrophysics Data System (ADS)

Zjupa, Jolanta; Springel, Volker

2017-04-01

The angular momentum properties of virialized dark matter haloes have been measured with good statistics in collisionless N-body simulations, but an equally accurate analysis of the baryonic spin is still missing. We employ the Illustris simulation suite, one of the first simulations of galaxy formation with full hydrodynamics that produces a realistic galaxy population in a sizeable volume, to quantify the baryonic spin properties for more than ˜320 000 haloes. We first compare the systematic differences between different spin parameter and halo definitions, and the impact of sample selection criteria on the derived properties. We confirm that dark-matter-only haloes exhibit a close to self-similar spin distribution in mass and redshift of lognormal form. However, the physics of galaxy formation radically changes the baryonic spin distribution. While the dark matter component remains largely unaffected, strong trends with mass and redshift appear for the spin of diffuse gas and the formed stellar component. With time, the baryons staying bound to the halo develop a misalignment of their spin vector with respect to dark matter, and increase their specific angular momentum by a factor of ˜1.3 in the non-radiative case and ˜1.8 in the full physics setup at z = 0. We show that this enhancement in baryonic spin can be explained by the combined effect of specific angular momentum transfer from dark matter on to gas during mergers and from feedback expelling low specific angular momentum gas from the halo. Our results challenge certain models for spin evolution and underline the significant changes induced by baryonic physics in the structure of haloes.

Dynamic Angular Control Of Thermal Therapy With Stationary Multi-Sectored Tubular Ultrasound Applicators Under MR Temperature Monitoring

NASA Astrophysics Data System (ADS)

Kinsey, Adam M.; Diederich, Chris J.; Nau, William H.; Ross, Anthony B.; Butts Pauly, Kim; Rieke, Viola; Sommer, Graham

2006-05-01

Multi-sectored ultrasound heating applicators with dynamic angular and longitudinal control of heating profiles are being investigated for the thermal treatment of tumors in sites such as prostate, uterus, and brain. Multi-sectored tubular ultrasound transducers with independent sector power control were incorporated into interstitial and transurethral applicators and provided dynamic angular control of a heating pattern without requiring device manipulation during treatment. Acoustic beam measurements of each applicator type demonstrated a 35-40° acoustic dead zone between each independent sector, with negligible mechanical or electrical coupling. Despite the acoustic dead zone between sectors, simulations and experiments under MR temperature (MRT) monitoring showed that the variance from the maximum lesion radius (scalloping) with all elements activated on a transducer was minimal and did not affect conformal heating of a target area. A biothermal model with a multi-point controller was used to adjust the applied power and treatment time of individual transducer segments as the tissue temperature changed in simulations of thermal lesions with both interstitial and transurethral applicators. Transurethral ultrasound applicators for benign prostatic hyperplasia (BPH) treatment with either three or four sectors conformed a thermal dose to a simulated target area in the angular and radial dimensions. The simulated treatment was controlled to a maximum temperature of 85°C, and had a maximum duration of 5 min when power was turned off as the 52°C temperature contour reach a predetermined control point for each sector in the tissue. Experiments conducted with multi-sectored applicators under MRT monitoring showed thermal ablation and hyperthermia treatments had little or no border `scalloping', conformed to a pretreatment target area, and correlated very well with the simulated thermal lesions. The radial penetration of the heat treatments in tissue with interstitial (1.5-1.8 mm OD transducer) and transurethral (2.5-4.0 mm OD transducer) applicators was at least 1.5 cm and 2.0 cm, respectively, for a treatment duration of 10 min. Angular control of thermal ablation and hyperthermia therapy often relies upon non-adjustable angular power deposition patterns and/or mechanical manipulation of the heating device. The multi-sectored ultrasound applicators developed in this study provide dynamic control of the angular heating distribution during treatment without device manipulation and maintain previously reported heating penetration and spatial control characteristics of similar ultrasound devices.

Interferometric angle monitor

NASA Technical Reports Server (NTRS)

Minott, P. O. (Inventor)

1983-01-01

Two mutually coherent light beams formed from a single monochromatic light source were directed to a reflecting surface of a rotatable object. They were reflected into an imaging optical lens having a focal plane optically at infinity. A series of interference fringes were formed in the focal plane which were translated linearly in response to angular rotation of the object. Photodetectors were located adjacent the focal plane to detect the fringe translation and output a signal in response to the translation. The signal was fed to a signal processor which was adapted to count the number of fringes detected and develop a measure of the angular rotation and direction of the object.

Mechanical Properties of Copper Processed by Equal Channel Angular Pressing

NASA Astrophysics Data System (ADS)

Sülleiová, K.; Ballóková, B.; Besterci, M.; Kvačkaj, T.

2017-12-01

The development of the nanostructure in commercial pure copper and the strength and ductility after severe plastic deformation (SPD) with the technology of equal channel angular pressing (ECAP) are analysed. Experimental results and analyses showed that both strength and ductility can be increased simultaneously by SPD. The final grain size decreased from the initial 50μm by SPD to 100-300 nm after 10 passes. An increase of the ductility together with an increase of strength caused by SPD are explained by a strong grain refinement and by a dynamic equilibrium of weakening and strengthening, and it is visible on the final static tensile test stress-strain charts.

Computational model for simulation of sequences of helicity and angular momentum transfer in turbid tissue-like scattering medium (Conference Presentation)

NASA Astrophysics Data System (ADS)

Doronin, Alexander; Meglinski, Igor

2017-02-01

Current report considers development of a unified Monte Carlo (MC) -based computational model for simulation of propagation of Laguerre-Gaussian (LG) beams in turbid tissue-like scattering medium. With a primary goal to proof the concept of using complex light for tissue diagnosis we explore propagation of LG beams in comparison with Gaussian beams for both linear and circular polarization. MC simulations of radially and azimuthally polarized LG beams in turbid media have been performed, classic phenomena such as preservation of the orbital angular momentum, optical memory and helicity flip are observed, detailed comparison is presented and discussed.

A theory of ring formation around Be stars

NASA Technical Reports Server (NTRS)

Huang, S.-S.

1976-01-01

A theory for the formation of gaseous rings around Be stars is developed which involves the combined effect of stellar rotation and radiation pressure. A qualitative scenario of ring formation is outlined in which the envelope formed about a star from ejected material is in the form of a disk in the equatorial plane, collisions between ejected gas blobs are inevitable, and particles with high angular momenta form a rotating ring around the star. A quantitative description of this process is then formulated by considering the angular momentum and dynamical energy of the ejected matter as well as those of the ring alone, without introducing any other assumptions.

Comparison of experiments and computations for cold gas spraying through a mask. Part 2

NASA Astrophysics Data System (ADS)

Klinkov, S. V.; Kosarev, V. F.; Ryashin, N. S.

2017-03-01

This paper presents experimental and simulation results of cold spray coating deposition using the mask placed above the plane substrate at different distances. Velocities of aluminum (mean size 30 μm) and copper (mean size 60 μm) particles in the vicinity of the mask are determined. It was found that particle velocities have angular distribution in flow with a representative standard deviation of 1.5-2 degrees. Modeling of coating formation behind the mask with account for this distribution was developed. The results of model agree with experimental data confirming the importance of particle angular distribution for coating deposition process in the masked area.

Nonlinear Attitude Control of Planar Structures in Space Using Only Internal Controls

NASA Technical Reports Server (NTRS)

Reyhanoglu, Mahmut; Mcclamroch, N. Harris

1993-01-01

An attitude control strategy for maneuvers of an interconnection of planar bodies in space is developed. It is assumed that there are no exogeneous torques and that torques generated by joint motors are used as means of control so that the total angular momentum of the multibody system is a constant, assumed to be zero. The control strategy utilizes the nonintegrability of the expression for the angular momentum. Large angle maneuvers can be designed to achieve an arbitrary reorientation of the multibody system with respect to an inertial frame. The theoretical background for carrying out the required maneuvers is summarized.

FIRST PHOTOMETRIC INVESTIGATION OF THE NEWLY DISCOVERED W UMa-TYPE BINARY STAR MR Com

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

Qian, S.-B.; Liu, N.-P.; Liao, W.-P.

By analyzing multi-color light curves of the newly discovered W UMa-type binary, MR Com, we discovered that it is a shallow-contact binary with a degree of contact factor of f = 10.0% {+-} 2.1%. Photometric solutions reveal that MR Com is a W-type system with a mass ratio of q = 3.9 where the less massive component is about 90 K hotter than the more massive one. By investigating all of the available times of minimum light, we found that the general trend of the Observed-Calculated (O - C) curve shows a downward parabolic variation while it undergoes a cyclicmore » variation with a small amplitude of 0.0031 days and a period of 10.1 yr. The downward parabolic change corresponds to a long-term decrease in the orbital period at a rate of P-dot = -5.3 x 10{sup -7} days yr{sup -1} that may be caused by a combination of a mass transfer and an angular momentum loss (AML) via magnetic braking. Among the 16 shallow-contact systems with a decreasing orbital period, MR Com has the lowest mass ratio (e.g., 1/q = 0.26). The shallow-contact configuration, the low-mass ratio, and the long-term period decrease all suggest that systems similar to MR Com are on the AML-controlled stage of the evolutionary scheme proposed by Qian. They will oscillate around a critical mass ratio and evolve into a deep contact with a higher mass ratio. The small-amplitude cyclic change in the O - C curve was analyzed for the light-travel time effect via the presence of an extremely cool stellar companion.« less

Multiple ash layers in late Quaternary sediments from the Central Indian Basin

NASA Astrophysics Data System (ADS)

Mascarenhas-Pereira, M. B. L.; Nagender Nath, B.; Iyer, S. D.; Borole, D. V.; Parthiban, G.; Jijin, R.; Khedekar, V.

2016-04-01

We have investigated three sediment cores collected from water depths > 5000 m along the transect 76°30‧E in close proximity to a fracture zone in the Central Indian Basin (CIB). The cores yielded five volcanic horizons of which four have visual and dispersed shards. Rhyolitic glass shards of bubble wall, platy, angular and blocky types were retrieved from various stratigraphic horizons in the cores. The abundance of glass shards, composition of bulk sediments, and 230Thexcess ages of the host sediments were used to distinguish the volcanic horizons. Of the four volcanic horizons, three are now newly reported and correspond to ages of ~ 85, 107-109 and 142-146 ka while the fourth horizon is of 70-75 ka. By using trace element ratios and Cr and Nb-based normative calculations, cryptotephra has been identified for the first time from the CIB sediment. The cryptotephra forms the fifth ash horizon and is of ~ 34 ka. A comparison with the published data on volcanic tephra in and around the Indian Ocean indicate the shard rich horizon (SRH) of 70-75 ka to resemble the Younger Toba Tuffs (YTT), while the other volcanic horizons that were deposited during different time periods do not correlate with any known marine or terrestrial records. These tephra layers have produced a tephrostratigraphic framework across the tectonically and volcanically complex regions of the CIB. Due to the lack of terrestrial equivalents of these tephra, it is hypothesized that the newly found volcanic horizons may have been derived from submarine volcanic eruptions. Multiple layers of submarine volcaniclastic deposits found at water depths as great as 5300 m reaffirm the growing belief that submarine phreatomagmatic eruptions are much more common in the intraplate region of the Indian Ocean than previously reported.

The Newly Identified Subsurface Hazlehurst Formation and Implications for the Tectonic Evolution of the South Georgia Rift Basin, Southeastern U.S.

NASA Astrophysics Data System (ADS)

Cao, R.; Knapp, J. H.

2016-12-01

Integration of new 2-D seismic reflection profile with existing wells and potential field data from southeastern Georgia, USA provide exciting discovery of a new stratigraphic unit associated with the post-rift phase of the South Georgia Rift (SGR) basins. These data document an apparent reversal of rift basin asymmetry across the Warner Robins Transfer Zone, and the apparent presence of a new sub-horizontal stratigraphic unit (informally named the Hazlehurst Formation) which overlies with angular unconformity an inferred Triassic rift basin (Valdosta Basin), and sits below the regional Coastal Plain unconformity. Triassic rifting of the supercontinent Pangea left behind numerous extensional basins on what is now the eastern North American margin. The SGR is thought to be the most regionally extensive and best preserved of these basins, which were capped by thick basalt -flows of the Central Atlantic Magmatic Province (CAMP) and later buried beneath the Cretaceous and younger Coastal Plain section. Because it is buried beneath the Coastal Plain, the SGR is only known through relatively sparse drilling and geophysical methods. With these new seismic data acquired in 2013 near Hazlehurst, Georgia, we are able to put more constraints into the tectonic history of the basin. We test several hypotheses related to the SGR: (1) the "Transfer Zone" had to exist to transmit extensional strain between rift sub-basins with reverse polarities; (2) the newly identified sub-horizontal stratigraphic interval ("Hazlehurst Formation"), with a possible Jurassic age may represent a post-rift phase of regional subsidence; (3) the extent of this new unit appears to cover most of the coastal plain from eastern Mississippi to South Carolina. The result of this study suggests the previous inferred extent of the might need revision.

Angular momentum of dwarf galaxies

NASA Astrophysics Data System (ADS)

Kurapati, Sushma; Chengalur, Jayaram N.; Pustilnik, Simon; Kamphuis, Peter

2018-05-01

Mass and specific angular momentum are two fundamental physical parameters of galaxies. We present measurements of the baryonic mass and specific angular momentum of 11 void dwarf galaxies derived from neutral hydrogen (HI) synthesis data. Rotation curves were measured using 3D and 2D tilted ring fitting routines, and the derived curves generally overlap within the error bars, except in the central regions where, as expected, the 3D routines give steeper curves. The specific angular momentum of void dwarfs is found to be high compared to an extrapolation of the trends seen for higher mass bulge-less spirals, but comparable to that of other dwarf irregular galaxies that lie outside of voids. As such, our data show no evidence for a dependence of the specific angular momentum on the large scale environment. Combining our data with the data from the literature, we find a baryonic threshold of ˜109.1 M⊙ for this increase in specific angular momentum. Interestingly, this threshold is very similar to the mass threshold below which the galaxy discs start to become systematically thicker. This provides qualitative support to the suggestion that the thickening of the discs, as well as the increase in specific angular momentum, are both results of a common physical mechanism, such as feedback from star formation. Quantitatively, however, the amount of star formation observed in our dwarfs appears insufficient to produce the observed increase in specific angular momentum. It is hence likely that other processes, such as cold accretion of high angular momentum gas, also play a role in increasing the specific angular momentum.

LETTER TO THE EDITOR: Iteratively-coupled propagating exterior complex scaling method for electron hydrogen collisions

NASA Astrophysics Data System (ADS)

Bartlett, Philip L.; Stelbovics, Andris T.; Bray, Igor

2004-02-01

A newly-derived iterative coupling procedure for the propagating exterior complex scaling (PECS) method is used to efficiently calculate the electron-impact wavefunctions for atomic hydrogen. An overview of this method is given along with methods for extracting scattering cross sections. Differential scattering cross sections at 30 eV are presented for the electron-impact excitation to the n = 1, 2, 3 and 4 final states, for both PECS and convergent close coupling (CCC), which are in excellent agreement with each other and with experiment. PECS results are presented at 27.2 eV and 30 eV for symmetric and asymmetric energy-sharing triple differential cross sections, which are in excellent agreement with CCC and exterior complex scaling calculations, and with experimental data. At these intermediate energies, the efficiency of the PECS method with iterative coupling has allowed highly accurate partial-wave solutions of the full Schrödinger equation, for L les 50 and a large number of coupled angular momentum states, to be obtained with minimal computing resources.

Solar Supergranulation Revealed as a Superposition of Traveling Waves

NASA Technical Reports Server (NTRS)

Gizon, L.; Duvall, T. L., Jr.; Schou, J.; Oegerle, William (Technical Monitor)

2002-01-01

40 years ago two new solar phenomena were described: supergranulation and the five-minute solar oscillations. While the oscillations have since been explained and exploited to determine the properties of the solar interior, the supergranulation has remained unexplained. The supergranules, appearing as convective-like cellular patterns of horizontal outward flow with a characteristic diameter of 30 Mm and an apparent lifetime of 1 day, have puzzling properties, including their apparent superrotation and the minute temperature variations over the cells. Using a 60-day sequence of data from the MDI (Michelson-Doppler Imager) instrument onboard the SOHO (Solar and Heliospheric Observatory) spacecraft, we show that the supergranulation pattern is formed by a superposition of traveling waves with periods of 5-10 days. The wave power is anisotropic with excess power in the direction of rotation and toward the equator, leading to spurious rotation rates and north-south flows as derived from correlation analyses. These newly discovered waves could play an important role in maintaining differential rotation in the upper convection zone by transporting angular momentum towards the equator.

Real object-based 360-degree integral-floating display using multiple depth camera

NASA Astrophysics Data System (ADS)

Erdenebat, Munkh-Uchral; Dashdavaa, Erkhembaatar; Kwon, Ki-Chul; Wu, Hui-Ying; Yoo, Kwan-Hee; Kim, Young-Seok; Kim, Nam

2015-03-01

A novel 360-degree integral-floating display based on the real object is proposed. The general procedure of the display system is similar with conventional 360-degree integral-floating displays. Unlike previously presented 360-degree displays, the proposed system displays the 3D image generated from the real object in 360-degree viewing zone. In order to display real object in 360-degree viewing zone, multiple depth camera have been utilized to acquire the depth information around the object. Then, the 3D point cloud representations of the real object are reconstructed according to the acquired depth information. By using a special point cloud registration method, the multiple virtual 3D point cloud representations captured by each depth camera are combined as single synthetic 3D point cloud model, and the elemental image arrays are generated for the newly synthesized 3D point cloud model from the given anamorphic optic system's angular step. The theory has been verified experimentally, and it shows that the proposed 360-degree integral-floating display can be an excellent way to display real object in the 360-degree viewing zone.

The structure of 193Au within the Interacting Boson Fermion Model

NASA Astrophysics Data System (ADS)

Thomas, T.; Bernards, C.; Régis, J.-M.; Albers, M.; Fransen, C.; Jolie, J.; Heinze, S.; Radeck, D.; Warr, N.; Zell, K.-O.

2014-02-01

A γγ angular correlation experiment investigating the nucleus 193Au is presented. In this work the level scheme of 193Au is extended by new level information on spins, multipolarities and newly observed states. The new results are compared with theoretical predictions from a general Interacting Boson Fermion Model (IBFM) calculation for the positive-parity states. The experimental data is in good agreement with an IBFM calculation using all proton orbitals between the shell closures at Z=50 and Z=126. As a dominant contribution of the d orbital to the wave function of the lowest excited states is observed, a truncated model of the IBFM using a Bose-Fermi symmetry is applied to the describe 193Au. Using the parameters of a fit performed for 193Au, the level scheme of 192Pt, the supersymmetric partner of 193Au, is predicted but shows a too small boson seniority splitting. We obtained a common fit by including states observed in 192Pt. With the new parameters a supersymmetric description of both nuclei is established.

Testing and Resilience of the Impact Origin of the Moon

NASA Technical Reports Server (NTRS)

Righter, K.; Canup, R. M.

2016-01-01

The leading hypothesis for the origin of the Moon is the giant impact model, which grew out of the post-Apollo science community. The hypothesis was able to explain the high E-M system angular momentum, the small lunar core, and consistent with the idea that the early Moon melted substantially. The standard hypothesis requires that the Moon be made entirely from the impactor, strangely at odds with the nearly identical oxygen isotopic composition of the Earth and Moon, compositions that might be expected to be different if Moon came from a distinct impactor. Subsequent geochemical research has highlighted the similarity of both geochemical and isotopic composition of the Earth and Moon, and measured small but significant amounts of volatiles in lunar glassy materials, both of which are seemingly at odds with the standard giant impact model. Here we focus on key geochemical measurements and spacecraft observations that have prompted a healthy re-evaluation of the giant impact model, provide an overview of physical models that are either newly proposed or slightly revised from previous ideas, to explain the new datasets.

Properties of {sup 112}Cd from the (n,n'{gamma}) reaction: Levels and level densities

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

Garrett, P. E.; Lehmann, H.; Jolie, J.

2001-08-01

Levels in {sup 112}Cd have been studied through the (n,n'{gamma}) reaction with monoenergetic neutrons. An extended set of experiments that included excitation functions, {gamma}-ray angular distributions, and {gamma}{gamma} coincidence measurements was performed. A total of 375 {gamma} rays were placed in a level scheme comprising 200 levels (of which 238 {gamma}-ray assignments and 58 levels are newly established) up to 4 MeV in excitation. No evidence to support the existence of 47 levels as suggested in previous studies was found, and these have been removed from the level scheme. From the results, a comparison of the level density is mademore » with the constant temperature and back-shifted Fermi gas models. The back-shifted Fermi gas model with the Gilbert-Cameron spin cutoff parameter provided the best overall fit. Without using the neutron resonance information and only fitting the cumulative number of low-lying levels, the level density parameters extracted are a sensitive function of the maximum energy used in the fit.« less

Gravitational radiation from rapidly rotating nascent neutron stars

NASA Technical Reports Server (NTRS)

Lai, Dong; Shapiro, Stuart L.

1995-01-01

We study the secular evolution and gravitational wave signature of a newly formed, rapidly rotating neutron star. The neutron star may arise from core collapse in a massive star or from the accretion-induced collapse of a white dwarf. After a brief dynamical phase, the nascent neutron star settles into an axisymmetric, secularly unstable state. Gravitational radiation drives the star to a nonaxisymmetric, stationary equilibrium configuration via the bar-mode instability. The emitted quasi-periodic gravitational waves have a unique signature: the wave frequency sweeps downward from a few hundred Hertz to zero, while the wave amplitude increase from zero to a maximum and then decays back to zero. Such a wave signal could detected by broadband gravitational wave interferometers currently being constructed. We also characterize two other types of gravitational wave signals that could arise in principle from a rapidly rotating, secularly unstable neutron star: a high-frequency (f greater than or approximately = 1000 Hz) wave which increases the pattern-speed of the star, and a wave that actually increases the angular momentum of the star.

SDSS J102111.02+491330.4: A Newly Discovered Gravitationally Lensed Quasar

NASA Astrophysics Data System (ADS)

Pindor, Bart; Eisenstein, Daniel J.; Gregg, Michael D.; Becker, Robert H.; Inada, Naohisa; Oguri, Masamune; Hall, Patrick B.; Johnston, David E.; Richards, Gordon T.; Schneider, Donald P.; Turner, Edwin L.; Brasi, Guido; Hinz, Philip M.; Kenworthy, Matthew A.; Miller, Doug; Barentine, J. C.; Brewington, Howard J.; Brinkmann, J.; Harvanek, Michael; Kleinman, S. J.; Krzesinski, Jurek; Long, Dan; Neilsen, Eric H., Jr.; Newman, Peter R.; Nitta, Atsuko; Snedden, Stephanie A.; York, Donald G.

2006-01-01

We report follow-up observations of two gravitational lens candidates identified in the Sloan Digital Sky Survey (SDSS) data set. We have confirmed that SDSS J102111.02+491330.4 is a previously unknown gravitationally lensed quasar. This lens system exhibits two images of a z=1.72 quasar, with an image separation of 1.14"+/-0.04". Optical and near-IR imaging of the system reveals the presence of the lensing galaxy between the two quasar images. Observations of SDSS J112012.12+671116.0 indicate that it is more likely a binary quasar than a gravitational lens. This system has two quasars at a redshift of z=1.49, with an angular separation of 1.49"+/-0.02". However, the two quasars have markedly different spectral energy distributions, and no lens galaxy is apparent in optical and near-IR images of this system. We also present a list of 31 SDSS lens candidates that follow-up observations have confirmed are not gravitational lenses. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

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

Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.

Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that ismore » capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.« less

Analysis of the geodetic residuals as differences between geodetic and sum of the atmospheric and ocean excitation of polar motion

NASA Astrophysics Data System (ADS)

Kolaczek, B.; Pasnicka, M.; Nastula, J.

2012-12-01

Up to now studies of geophysical excitation of polar motion containing AAM (Atmospheric Angular Momentum), OAM (Oceanic Angular Momentum) and HAM (Hydrological Angular Momentum) excitation functions of polar motion have not achieved the total agreement between geophysical and determined geodetic excitation (GAM, Geodetic AngularMomentum) functions of polar motion...

A goal-based angular adaptivity method for thermal radiation modelling in non grey media

NASA Astrophysics Data System (ADS)

Soucasse, Laurent; Dargaville, Steven; Buchan, Andrew G.; Pain, Christopher C.

2017-10-01

This paper investigates for the first time a goal-based angular adaptivity method for thermal radiation transport, suitable for non grey media when the radiation field is coupled with an unsteady flow field through an energy balance. Anisotropic angular adaptivity is achieved by using a Haar wavelet finite element expansion that forms a hierarchical angular basis with compact support and does not require any angular interpolation in space. The novelty of this work lies in (1) the definition of a target functional to compute the goal-based error measure equal to the radiative source term of the energy balance, which is the quantity of interest in the context of coupled flow-radiation calculations; (2) the use of different optimal angular resolutions for each absorption coefficient class, built from a global model of the radiative properties of the medium. The accuracy and efficiency of the goal-based angular adaptivity method is assessed in a coupled flow-radiation problem relevant for air pollution modelling in street canyons. Compared to a uniform Haar wavelet expansion, the adapted resolution uses 5 times fewer angular basis functions and is 6.5 times quicker, given the same accuracy in the radiative source term.

Analysis of angular momentum properties of photons emitted in fundamental atomic processes

NASA Astrophysics Data System (ADS)

Zaytsev, V. A.; Surzhykov, A. S.; Shabaev, V. M.; Stöhlker, Th.

2018-04-01

Many atomic processes result in the emission of photons. Analysis of the properties of emitted photons, such as energy and angular distribution as well as polarization, is regarded as a powerful tool for gaining more insight into the physics of corresponding processes. Another characteristic of light is the projection of its angular momentum upon propagation direction. This property has attracted a special attention over the past decades due to studies of twisted (or vortex) light beams. Measurements being sensitive to this projection may provide valuable information about the role of angular momentum in the fundamental atomic processes. Here we describe a simple theoretical method for determination of the angular momentum properties of the photons emitted in various atomic processes. This method is based on the evaluation of expectation value of the total angular momentum projection operator. To illustrate the method, we apply it to the textbook examples of plane-wave, spherical-wave, and Bessel light. Moreover, we investigate the projection of angular momentum for the photons emitted in the process of the radiative recombination with ionic targets. It is found that the recombination photons do carry a nonzero projection of the orbital angular momentum.

Angular Spacing Control for Segmented Data Pages in Angle-Multiplexed Holographic Memory

NASA Astrophysics Data System (ADS)

Kinoshita, Nobuhiro; Muroi, Tetsuhiko; Ishii, Norihiko; Kamijo, Koji; Kikuchi, Hiroshi; Shimidzu, Naoki; Ando, Toshio; Masaki, Kazuyoshi; Shimizu, Takehiro

2011-09-01

To improve the recording density of angle-multiplexed holographic memory, it is effective to increase the numerical aperture of the lens and to shorten the wavelength of the laser source as well as to increase the multiplexing number. The angular selectivity of a hologram, which determines the multiplexing number, is dependent on the incident angle of not only the reference beam but also the signal beam to the holographic recording medium. The actual signal beam, which is a convergent or divergent beam, is regarded as the sum of plane waves that have different propagation directions, angular selectivities, and optimal angular spacings. In this paper, focusing on the differences in the optimal angular spacing, we proposed a method to control the angular spacing for each segmented data page. We investigated the angular selectivity of a hologram and crosstalk for segmented data pages using numerical simulation. The experimental results showed a practical bit-error rate on the order of 10-3.

Amplification of Angular Rotations Using Weak Measurements

NASA Astrophysics Data System (ADS)

Magaña-Loaiza, Omar S.; Mirhosseini, Mohammad; Rodenburg, Brandon; Boyd, Robert W.

2014-05-01

We present a weak measurement protocol that permits a sensitive estimation of angular rotations based on the concept of weak-value amplification. The shift in the state of a pointer, in both angular position and the conjugate orbital angular momentum bases, is used to estimate angular rotations. This is done by an amplification of both the real and imaginary parts of the weak-value of a polarization operator that has been coupled to the pointer, which is a spatial mode, via a spin-orbit coupling. Our experiment demonstrates the first realization of weak-value amplification in the azimuthal degree of freedom. We have achieved effective amplification factors as large as 100, providing a sensitivity that is on par with more complicated methods that employ quantum states of light or extremely large values of orbital angular momentum.

Angular-domain scattering interferometry.

PubMed

Shipp, Dustin W; Qian, Ruobing; Berger, Andrew J

2013-11-15

We present an angular-scattering optical method that is capable of measuring the mean size of scatterers in static ensembles within a field of view less than 20 μm in diameter. Using interferometry, the method overcomes the inability of intensity-based models to tolerate the large speckle grains associated with such small illumination areas. By first estimating each scatterer's location, the method can model between-scatterer interference as well as traditional single-particle Mie scattering. Direct angular-domain measurements provide finer angular resolution than digitally transformed image-plane recordings. This increases sensitivity to size-dependent scattering features, enabling more robust size estimates. The sensitivity of these angular-scattering measurements to various sizes of polystyrene beads is demonstrated. Interferometry also allows recovery of the full complex scattered field, including a size-dependent phase profile in the angular-scattering pattern.

Dynamo magnetic field-induced angular momentum transport in protostellar nebulae - The 'minimum mass' protosolar nebula

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Levy, E. H.

1990-01-01

Magnetic torques can produce angular momentum redistribution in protostellar nebulas. Dynamo magnetic fields can be generated in differentially rotating and turbulent nebulas and can be the source of magnetic torques that transfer angular momentum from a protostar to a disk, as well as redistribute angular momentum within a disk. A magnetic field strength of 100-1000 G is needed to transport the major part of a protostar's angular momentum into a surrounding disk in a time characteristic of star formation, thus allowing formation of a solar-system size protoplanetary nebula in the usual 'minimum-mass' model of the protosolar nebula. This paper examines the possibility that a dynamo magnetic field could have induced the needed angular momentum transport from the proto-Sun to the protoplanetary nebula.

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla.

PubMed

Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

2015-03-01

Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1(-)) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI. Copyright © 2014 Elsevier Inc. All rights reserved.

Response of an Impact Test Apparatus for Fall Protective Headgear Testing Using a Hybrid-III Head/Neck Assembly

PubMed Central

Caccese, V.; Ferguson, J.; Lloyd, J.; Edgecomb, M.; Seidi, M.; Hajiaghamemar, M.

2017-01-01

A test method based upon a Hybrid-III head and neck assembly that includes measurement of both linear and angular acceleration is investigated for potential use in impact testing of protective headgear. The test apparatus is based upon a twin wire drop test system modified with the head/neck assembly and associated flyarm components. This study represents a preliminary assessment of the test apparatus for use in the development of protective headgear designed to prevent injury due to falls. By including angular acceleration in the test protocol it becomes possible to assess and intentionally reduce this component of acceleration. Comparisons of standard and reduced durometer necks, various anvils, front, rear, and side drop orientations, and response data on performance of the apparatus are provided. Injury measures summarized for an unprotected drop include maximum linear and angular acceleration, head injury criteria (HIC), rotational injury criteria (RIC), and power rotational head injury criteria (PRHIC). Coefficient of variation for multiple drops ranged from 0.4 to 6.7% for linear acceleration. Angular acceleration recorded in a side drop orientation resulted in highest coefficient of variation of 16.3%. The drop test apparatus results in a reasonably repeatable test method that has potential to be used in studies of headgear designed to reduce head impact injury. PMID:28216804

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

NASA Astrophysics Data System (ADS)

Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

2015-03-01

Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1-) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI.

Far Infrared All-Sky Survey

NASA Technical Reports Server (NTRS)

Richards, Paul L.

1998-01-01

Precise measurements of the angular power spectrum of the Cosmic Microwave Background (CMB) anisotropy will revolutionize cosmology. These measurements will discriminate between competing cosmological models and, if the standard inflationary scenario is correct, will determine each of the fundamental cosmological parameters with high precision. The astrophysics community has recognized this potential: the orbital experiments MAP and PLANCK, have been approved to measure CMB anisotropy. Balloon-borne experiments can realize much of this potential before these missions are launched. Additionally, properly designed balloon-borne experiments can complement MAP in frequency and angular resolution and can give the first realistic test of the instrumentation proposed for the high frequency instrument on PLANCK. The MAXIMA experiment is part of the MAXIMA/BOOMERANG collaboration which is doing balloon observations of the angular power spectrum of the Cosmic Microwave Background from l = 10 to l = 800. These experiments are designed to use the benefits of both North American and Antarctic long-duration ballooning to full advantage. We have developed several new technologies that together allow the power spectrum to be measured with unprecedented combination of angular resolution, beam throw, sensitivity, sky coverage and control of systematic effects. These technologies are the basis for the high frequency instrument for the PLANCK mission. Our measurements will strongly discriminate between models of the origin and evolution of structure in the universe and, for many models, will determine the value of the basic cosmological parameters to high precision.

Nonlinear dynamic modeling of a simple flexible rotor system subjected to time-variable base motions

NASA Astrophysics Data System (ADS)

Chen, Liqiang; Wang, Jianjun; Han, Qinkai; Chu, Fulei

2017-09-01

Rotor systems carried in transportation system or under seismic excitations are considered to have a moving base. To study the dynamic behavior of flexible rotor systems subjected to time-variable base motions, a general model is developed based on finite element method and Lagrange's equation. Two groups of Euler angles are defined to describe the rotation of the rotor with respect to the base and that of the base with respect to the ground. It is found that the base rotations would cause nonlinearities in the model. To verify the proposed model, a novel test rig which could simulate the base angular-movement is designed. Dynamic experiments on a flexible rotor-bearing system with base angular motions are carried out. Based upon these, numerical simulations are conducted to further study the dynamic response of the flexible rotor under harmonic angular base motions. The effects of base angular amplitude, rotating speed and base frequency on response behaviors are discussed by means of FFT, waterfall, frequency response curve and orbits of the rotor. The FFT and waterfall plots of the disk horizontal and vertical vibrations are marked with multiplications of the base frequency and sum and difference tones of the rotating frequency and the base frequency. Their amplitudes will increase remarkably when they meet the whirling frequencies of the rotor system.

Diverse trends of electron correlation effects for properties with different radial and angular factors in an atomic system: a case study in Ca+

NASA Astrophysics Data System (ADS)

Kumar, Pradeep; Li, Cheng-Bin; Sahoo, B. K.

2018-03-01

Dependencies of electron correlation effects with the rank and radial behavior of spectroscopic properties are analyzed in the singly charged calcium ion (Ca+). To demonstrate these trends, we have determined field shift constants, magnetic dipole and electric quadrupole hyperfine structure constants, Landé g J factors, and electric quadrupole moments that are described by electronic operators with different radial and angular factors. Radial dependencies are investigated by comparing correlation trends among the properties that have similar angular factors and vice versa. To highlight these observations, we present results from the mean-field approach to all-orders along with intermediate contributions. Contributions from higher relativistic corrections are also given. These findings suggest that sometime lower-order approximations can give results agreeing with the experimental results, but inclusion of some of higher-order correlation effects can cause large disagreement with the experimental values. Therefore, validity of a method for accurate evaluation of atomic properties can be tested by performing calculations of several properties simultaneously that have diverse dependencies on the angular and radial factors and comparing with the available experimental results. Nevertheless, it is imperative to include full triple and quadrupole excitations in the all-order many-body methods for high-precision calculations that are yet to be developed adopting spherical coordinate system for atomic studies.

Visual ergonomic aspects of glare on computer displays: glossy screens and angular dependence

NASA Astrophysics Data System (ADS)

Brunnström, Kjell; Andrén, Börje; Konstantinides, Zacharias; Nordström, Lukas

2007-02-01

Recently flat panel computer displays and notebook computer are designed with a so called glare panel i.e. highly glossy screens, have emerged on the market. The shiny look of the display appeals to the costumers, also there are arguments that the contrast, colour saturation etc improves by using a glare panel. LCD displays suffer often from angular dependent picture quality. This has been even more pronounced by the introduction of Prism Light Guide plates into displays for notebook computers. The TCO label is the leading labelling system for computer displays. Currently about 50% of all computer displays on the market are certified according to the TCO requirements. The requirements are periodically updated to keep up with the technical development and the latest research in e.g. visual ergonomics. The gloss level of the screen and the angular dependence has recently been investigated by conducting user studies. A study of the effect of highly glossy screens compared to matt screens has been performed. The results show a slight advantage for the glossy screen when no disturbing reflexes are present, however the difference was not statistically significant. When disturbing reflexes are present the advantage is changed into a larger disadvantage and this difference is statistically significant. Another study of angular dependence has also been performed. The results indicates a linear relationship between the picture quality and the centre luminance of the screen.

Learning beyond Graduation: Exploring Newly Qualified Specialists' Entrance into Daily Practice from a Learning Perspective

ERIC Educational Resources Information Center

Cuyvers, Katrien; Donche, Vincent; Van den Bossche, Piet

2016-01-01

The entrance of newly qualified medical specialists into daily practice is considered to be a stressful period in which curriculum support is absent. Although engaging in both personal and professional learning and development activities is recognized fundamental for lifelong professional competence, research on medical professionals' entrance…

76 FR 78929 - Establishing Timeframes for Implementation of Product Safety Labeling Changes; Request for Comments

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-20

... labeling; (2) supply chain issues; and, (3) other issues. FDA may use the information received to develop...? B. Supply Chain Issues 3. What are the supply chain factors (including storage, shipping, and... the optimal point in the supply chain (e.g., newly manufactured product, newly shipped product) and...

Polymorphic SSR markers for Plasmopara obducens (Peronosporaceae), the newly emergent downy mildew pathogen of Impatiens (Balsaminaceae)

USDA-ARS?s Scientific Manuscript database

Premise of the study: Microsatellite markers were developed for Plasmopara obducens, the causal agent of the newly emergent downy mildew disease of Impatiens walleriana. Methods and Results: A 151.2 Mb draft genome assembly was generated from P. obducens using Illumina technology and mined to identi...

Efficacy of Intra-articular Injection of a Newly Developed Plasma Rich in Growth Factor (PRGF) Versus Hyaluronic Acid on Pain and Function of Patients with Knee Osteoarthritis: A Single-Blinded Randomized Clinical Trial.

PubMed

Raeissadat, Seyed Ahmad; Rayegani, Seyed Mansoor; Ahangar, Azadeh Gharooee; Abadi, Porya Hassan; Mojgani, Parviz; Ahangar, Omid Gharooi

2017-01-01

Knee osteoarthritis is the most common joint disease. We aimed to compare the efficacy and safety of intra-articular injection of a newly developed plasma rich in growth factor (PRGF) versus hyaluronic acid (HA) on pain and function of patients with knee osteoarthritis. In this single-blinded randomized clinical trial, patients with symptomatic osteoarthritis of knee were assigned to receive 2 intra-articular injections of our newly developed PRGF in 3 weeks or 3 weekly injections of HA. Our primary outcome was the mean change from baseline until 2 and 6 months post intervention in scores of visual analog scale, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Lequesne index. We used analysis of variance for repeated-measures statistical test. A total of 69 patients entered final analysis. The mean age of patients was 58.2 ± 7.41 years and 81.2% were women. In particular, total WOMAC index decreased from 42.9 ± 13.51 to 26.8 ± 13.45 and 24.4 ± 16.54 at 2 and 6 months in the newly developed PRGF group (within subjects P  = .001), and from 38.8 ± 12.62 to 27.8 ± 11.01 and 27.4 ± 11.38 at 2 and 6 months in the HA group (within subjects P  = .001), respectively (between subjects P  = .631). There was no significant difference between PRGF and HA groups in patients' satisfaction and minor complications of injection, whereas patients in HA group reported significantly lower injection-induced pain. In 6 months follow up, our newly developed PRGF and HA, both are effective options to decrease pain and improvement of function in patients with symptomatic mild to moderate knee osteoarthritis.

A Standardized Education Checklist for Parents of Children Newly Diagnosed With Cancer: A Report From the Children's Oncology Group.

PubMed

Rodgers, Cheryl; Bertini, Vanessa; Conway, Mary Ashe; Crosty, Ashley; Filice, Angela; Herring, Ruth Anne; Isbell, Julie; Lown DrPH, E Anne; Miller, Kristina; Perry, Margaret; Sanborn, Paula; Spreen, Nicole; Tena, Nancy; Winkle, Cindi; Darling, Joan; Slaven, Abigail; Sullivan, Jeneane; Tomlinson, Kathryn M; Windt, Kate; Hockenberry, Marilyn; Landier, Wendy

2018-03-01

Parents of children newly diagnosed with cancer must acquire new knowledge and skills in order to safely care for their child at home. Institutional variation exists in the methods and content used by nurses in providing the initial education. The goal of this project was to develop a checklist, standardized across institutions, to guide nursing education provided to parents of children newly diagnosed with cancer. A team of 21 members (19 nurses and 2 parent advocates) used current hospital educational checklists, expert consensus recommendations, and a series of iterative activities and discussions to develop one standardized checklist. The final checklist specifies primary topics that are essential to teach prior to the initial hospital discharge, secondary topics that should be discussed within the first month after the cancer diagnosis, and tertiary topics that should be discussed prior to completion of therapy. This checklist is designed to guide education and will set the stage for future studies to identify effective teaching strategies that optimize the educational process for parents of children newly diagnosed with cancer.

Angular multiplexing holograms of four images recorded on photopolymer films with recording-film-thickness-dependent holographic characteristics

NASA Astrophysics Data System (ADS)

Osabe, Keiichi; Kawai, Kotaro

2017-03-01

In this study, angular multiplexing hologram recording photopolymer films were studied experimentally. The films contained acrylamide as a monomer, eosin Y as a sensitizer, and triethanolamine as a promoter in a polyvinyl alcohol matrix. In order to determine the appropriate thickness of the photopolymer films for angular multiplexing, photopolymer films with thicknesses of 29-503 μm were exposed to two intersecting beams of a YVO laser at a wavelength of 532 nm to form a holographic grating with a spatial frequency of 653 line/mm. The diffraction efficiencies as a function of the incident angle of reconstruction were measured. A narrow angular bandwidth and high diffraction efficiency are required for angular multiplexing; hence, we define the Q value, which is the diffraction efficiency divided by half the bandwidth. The Q value of the films depended on the thickness of the films, and was calculated based on the measured diffraction efficiencies. The Q value of a 297-μm-thick film was the highest of the all films. Therefore, the angular multiplexing experiments were conducted using 300-μm-thick films. In the angular multiplexing experiments, the object beam transmitted by a square aperture was focused by a Fourier transform lens and interfered with a reference beam. The maximum order of angular multiplexing was four. The signal intensity that corresponds to the squared-aperture transmission and the noise intensity that corresponds to transmission without the square aperture were measured. The signal intensities decreased as the order of angular multiplexing increased, and the noise intensities were not dependent on the order of angular multiplexing.

A Detailed Motion Analysis of the Angular Velocity Between the Vocal Folds During Throat Clearing Using High-speed Digital Imaging.

PubMed

Iwahashi, Toshihiko; Ogawa, Makoto; Hosokawa, Kiyohito; Kato, Chieri; Inohara, Hidenori

2016-11-01

To assess the angular velocity between the vocal folds just before the compression phase of throat clearing (TC) using high-speed digital imaging (HSDI) of the larynx. Twenty normal healthy adults (13 males and seven females) were enrolled in the study. Each participant underwent transnasal laryngo-fiberscopy, and was asked to perform weak/strong TC followed by a comfortable, sustained vowel phonation while recording an HSDI movie (4000 frames/s) of the larynx. Using a motion analysis, the changes in the vocal fold angle and angular velocity during vocal fold adduction were assessed. Subsequently, we calculated the average angular velocities in the ranges of 100-80%, 80-20%, and 20-0% from all of the angular changes. The motion analysis demonstrated that the changes in the angular velocity resulted in polynomial-like and sigmoid curves during TC and vowel phonation, respectively. The angular velocities during weak TC were significantly higher in the 20-0%, 80-20%, and 100-80% regions (in order); the 80-20% angular velocity in vocal fold adduction during phonation was highest. The 20-0% angular velocity during strong TC was more than twofold higher than 20-0% angular velocity during phonation. The present results confirmed that the closing motions of the vocal folds accelerate throughout the precompression closing phase of a TC episode, and decelerate just before the impact between the vocal folds at the onset of phonation, suggesting that the vocal fold velocity generated by TC is sufficient to damage the laryngeal tissues. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Aging curve of neuromotor function by pronation and supination of forearms using three-dimensional wireless acceleration and angular velocity sensors.

PubMed

Kaneko, M; Okui, H; Hirakawa, G; Ishinishi, H; Katayama, Y; Iramina, K

2012-01-01

We have developed an evaluation system for pronation and supination of forearms. The motion of pronation and supination of the forearm is used as a diagnosis method of developmental disability, etc. However, this diagnosis method has a demerit in which diagnosis results between doctors are not consistent. It is hoped that a more quantitative and simple evaluation method is established. Moreover it is hoped a diagnostic criteria obtained from healthy subjects can be established to diagnose developmental disorder patients. We developed a simple and portable evaluation system for pronation and supination of forearms. Three-dimensional wireless acceleration and angular velocity sensors are used for this system. In this study, pronation and supination of forearms of 570 subjects (subjects aged 6-12, 21-100) were examined. We could obtain aging curves in the neuromotor function of pronation and supination. These aging curves obtained by our developed system, has the potential to become diagnostic criteria for a developmental disability, etc.

Hubble Space Telescope Angular Velocity Estimation During the Robotic Servicing Mission

NASA Technical Reports Server (NTRS)

Thienel, Julie K.; Queen, Steven Z.; VanEepoel, John M.; Sanner, Robert M.

2005-01-01

During the Hubble Robotic Servicing Mission, the Hubble Space Telescope (HST) attitude and rates are necessary to achieve the capture of HST by the Hubble Robotic Vehicle (HRV). The attitude and rates must be determined without the HST gyros or HST attitude estimates. The HRV will be equipped with vision-based sensors, capable of estimating the relative attitude between HST and HRV. The HST attitude is derived from the measured relative attitude and the HRV computed inertial attitude. However, the relative rate between HST and HRV cannot be measured directly. Therefore, the HST rate with respect to inertial space is not known. Two approaches are developed to estimate the HST rates. Both methods utilize the measured relative attitude and the HRV inertial attitude and rates. First, a nonlinear estimator is developed. The nonlinear approach estimates the HST rate through an estimation of the inertial angular momentum. Second, a linearized approach is developed. The linearized approach is based on more traditional Extended Kalman filter techniques. Simulation test results for both methods are given.

Jet angularity measurements for single inclusive jet production

NASA Astrophysics Data System (ADS)

Kang, Zhong-Bo; Lee, Kyle; Ringer, Felix

2018-04-01

We study jet angularity measurements for single-inclusive jet production at the LHC. Jet angularities depend on a continuous parameter a allowing for a smooth interpolation between different traditional jet shape observables. We establish a factorization theorem within Soft Collinear Effective Theory (SCET) where we consistently take into account in- and out-of-jet radiation by making use of semi-inclusive jet functions. For comparison, we elaborate on the differences to jet angularities measured on an exclusive jet sample. All the necessary ingredients for the resummation at next-to-leading logarithmic (NLL) accuracy are presented within the effective field theory framework. We expect semiinclusive jet angularity measurements to be feasible at the LHC and we present theoretical predictions for the relevant kinematic range. In addition, we investigate the potential impact of jet angularities for quark-gluon discrimination.

A new open-loop fiber optic gyro error compensation method based on angular velocity error modeling.

PubMed

Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing

2015-02-27

With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage u and temperature T as the input variables and angular velocity error Δω as the output variable. Firstly, the angular velocity error Δω is extracted from OFOG output signals, and then the output voltage u, temperature T and angular velocity error Δω are used as the learning samples to train a Radial-Basis-Function (RBF) neural network model. Then the nonlinear mapping model over T, u and Δω is established and thus Δω can be calculated automatically to compensate OFOG errors according to T and u. The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by 97.0%, 97.1% and 96.5% relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by 1.6%, 1.4% and 1.42%, respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity.

A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular Velocity Error Modeling

PubMed Central

Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing

2015-01-01

With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage u and temperature T as the input variables and angular velocity error Δω as the output variable. Firstly, the angular velocity error Δω is extracted from OFOG output signals, and then the output voltage u, temperature T and angular velocity error Δω are used as the learning samples to train a Radial-Basis-Function (RBF) neural network model. Then the nonlinear mapping model over T, u and Δω is established and thus Δω can be calculated automatically to compensate OFOG errors according to T and u. The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by 97.0%, 97.1% and 96.5% relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by 1.6%, 1.4% and 1.2%, respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity. PMID:25734642

Closed-form integrator for the quaternion (euler angle) kinematics equations

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A. (Inventor)

2000-01-01

The invention is embodied in a method of integrating kinematics equations for updating a set of vehicle attitude angles of a vehicle using 3-dimensional angular velocities of the vehicle, which includes computing an integrating factor matrix from quantities corresponding to the 3-dimensional angular velocities, computing a total integrated angular rate from the quantities corresponding to a 3-dimensional angular velocities, computing a state transition matrix as a sum of (a) a first complementary function of the total integrated angular rate and (b) the integrating factor matrix multiplied by a second complementary function of the total integrated angular rate, and updating the set of vehicle attitude angles using the state transition matrix. Preferably, the method further includes computing a quanternion vector from the quantities corresponding to the 3-dimensional angular velocities, in which case the updating of the set of vehicle attitude angles using the state transition matrix is carried out by (a) updating the quanternion vector by multiplying the quanternion vector by the state transition matrix to produce an updated quanternion vector and (b) computing an updated set of vehicle attitude angles from the updated quanternion vector. The first and second trigonometric functions are complementary, such as a sine and a cosine. The quantities corresponding to the 3-dimensional angular velocities include respective averages of the 3-dimensional angular velocities over plural time frames. The updating of the quanternion vector preserves the norm of the vector, whereby the updated set of vehicle attitude angles are virtually error-free.

The use of newly developed real-time PCR for the rapid identification of bacteria in culture-negative osteomyelitis.

PubMed

Kobayashi, Naomi; Bauer, Thomas W; Sakai, Hiroshige; Togawa, Daisuke; Lieberman, Isador H; Fujishiro, Takaaki; Procop, Gary W

2006-12-01

We report a case of a culture-negative osteomyelitis in which our newly developed real-time polymerase chain reaction (PCR) could differentiate Staphylococcus aureus from Staphylococcus epidermidis. This is the first report that described the application of this novel assay to an orthopedics clinical sample. This assay may be useful for other clinical culture-negative cases in a combination with a broad-spectrum assay as a rapid microorganism identification method.

Design and Calibration of the ARL Mach 3 High Reynolds Number Facility

DTIC Science & Technology

1975-01-01

degrees Rankine. Test rhombus determinations included lateral and longitudinal Mach number distributions and flow angularity measurements. A...43 3. THE TUNNEL EMPTY MACH NUMBER DISTRIBUTION 45 4. THE CENTERLINE RMS MACH NUMBER 46 5. FLOW ANGULARITY MEASUREMENTS 46 6. BLOCKAGE TESTS... Angularity Wedge Scale Drawing of Flow Angularity Cone Normalized Surface Pressure Difference versus Angle of Attack at xp/xr = - 0.690 for po

GALACTIC ANGULAR MOMENTUM IN THE ILLUSTRIS SIMULATION: FEEDBACK AND THE HUBBLE SEQUENCE

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

Genel, Shy; Fall, S. Michael; Snyder, Gregory F.

We study the stellar angular momentum of thousands of galaxies in the Illustris cosmological simulation, which captures gravitational and gas dynamics within galaxies, as well as feedback from stars and black holes. We find that the angular momentum of the simulated galaxies matches observations well, and in particular two distinct relations are found for late-type versus early-type galaxies. The relation for late-type galaxies corresponds to the value expected from full conservation of the specific angular momentum generated by cosmological tidal torques. The relation for early-type galaxies corresponds to retention of only ∼30% of that, but we find that those early-typemore » galaxies with low angular momentum at z = 0 nevertheless reside at high redshift on the late-type relation. Some of them abruptly lose angular momentum during major mergers. To gain further insight, we explore the scaling relations in simulations where the galaxy formation physics is modified with respect to the fiducial model. We find that galactic winds with high mass-loading factors are essential for obtaining the high angular momentum relation typical for late-type galaxies, while active galactic nucleus feedback largely operates in the opposite direction. Hence, feedback controls the stellar angular momentum of galaxies, and appears to be instrumental for establishing the Hubble sequence.« less

Optimal simulations of ultrasonic fields produced by large thermal therapy arrays using the angular spectrum approach

PubMed Central

Zeng, Xiaozheng; McGough, Robert J.

2009-01-01

The angular spectrum approach is evaluated for the simulation of focused ultrasound fields produced by large thermal therapy arrays. For an input pressure or normal particle velocity distribution in a plane, the angular spectrum approach rapidly computes the output pressure field in a three dimensional volume. To determine the optimal combination of simulation parameters for angular spectrum calculations, the effect of the size, location, and the numerical accuracy of the input plane on the computed output pressure is evaluated. Simulation results demonstrate that angular spectrum calculations performed with an input pressure plane are more accurate than calculations with an input velocity plane. Results also indicate that when the input pressure plane is slightly larger than the array aperture and is located approximately one wavelength from the array, angular spectrum simulations have very small numerical errors for two dimensional planar arrays. Furthermore, the root mean squared error from angular spectrum simulations asymptotically approaches a nonzero lower limit as the error in the input plane decreases. Overall, the angular spectrum approach is an accurate and robust method for thermal therapy simulations of large ultrasound phased arrays when the input pressure plane is computed with the fast nearfield method and an optimal combination of input parameters. PMID:19425640

Variable dose rate single-arc IMAT delivered with a constant dose rate and variable angular spacing

NASA Astrophysics Data System (ADS)

Tang, Grace; Earl, Matthew A.; Yu, Cedric X.

2009-11-01

Single-arc intensity-modulated arc therapy (IMAT) has gained worldwide interest in both research and clinical implementation due to its superior plan quality and delivery efficiency. Single-arc IMAT techniques such as the Varian RapidArc™ deliver conformal dose distributions to the target in one single gantry rotation, resulting in a delivery time in the order of 2 min. The segments in these techniques are evenly distributed within an arc and are allowed to have different monitor unit (MU) weightings. Therefore, a variable dose-rate (VDR) is required for delivery. Because the VDR requirement complicates the control hardware and software of the linear accelerators (linacs) and prevents most existing linacs from delivering IMAT, we propose an alternative planning approach for IMAT using constant dose-rate (CDR) delivery with variable angular spacing. We prove the equivalence by converting VDR-optimized RapidArc plans to CDR plans, where the evenly spaced beams in the VDR plan are redistributed to uneven spacing such that the segments with larger MU weighting occupy a greater angular interval. To minimize perturbation in the optimized dose distribution, the angular deviation of the segments was restricted to <=± 5°. This restriction requires the treatment arc to be broken into multiple sectors such that the local MU fluctuation within each sector is reduced, thereby lowering the angular deviation of the segments during redistribution. The converted CDR plans were delivered with a single gantry sweep as in the VDR plans but each sector was delivered with a different value of CDR. For four patient cases, including two head-and-neck, one brain and one prostate, all CDR plans developed with the variable spacing scheme produced similar dose distributions to the original VDR plans. For plans with complex angular MU distributions, the number of sectors increased up to four in the CDR plans in order to maintain the original plan quality. Since each sector was delivered with a different dose rate, extra mode-up time (xMOT) was needed between the transitions of the successive sectors during delivery. On average, the delivery times of the CDR plans were approximately less than 1 min longer than the treatment times of the VDR plans, with an average of about 0.33 min of xMOT per sector transition. The results have shown that VDR may not be necessary for single-arc IMAT. Using variable angular spacing, VDR RapidArc plans can be implemented into the clinics that are not equipped with the new VDR-enabled machines without compromising the plan quality or treatment efficiency. With a prospective optimization approach using variable angular spacing, CDR delivery times can be further minimized while maintaining the high delivery efficiency of single-arc IMAT treatment.

Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

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

Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.

Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets withmore » various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR values were found to increase with decreasing RMSE values of projection angular gaps with strong correlations (r ≈ −0.7) regardless of the reconstruction algorithm used. Conclusions: Based on the authors’ results, displacement-based binning methods, better reconstruction algorithms, and the acquisition of even projection angular views are the most important factors to consider for improving thoracic 4D-CBCT image quality. In view of the practical issues with displacement-based binning and the fact that projection angular spacing is not currently directly controllable, development of better reconstruction algorithms represents the most effective strategy for improving image quality in thoracic 4D-CBCT for IGRT applications at the current stage.« less

Being a team leader: newly registered nurses relate their experiences.

PubMed

Ekström, Louise; Idvall, Ewa

2015-01-01

This paper presents a study that explores how newly qualified registered nurses experience their leadership role in the ward-based nursing care team. A nurse's clinical leadership affects the quality of care provided. Newly qualified nurses experience difficulties during the transition period from student to qualified professional and find it challenging to lead nursing care. Twelve nurses were interviewed and the transcribed texts analysed using qualitative content analysis to assess both manifest and latent content. Five themes were identified: feeling stranded; forming well-functioning teams; learning to lead; having the courage, strength, and desire to lead; and ensuring appropriate care. The findings indicate that many factors limit nurses' leadership but some circumstances are supportive. The leadership prerequisites for newly registered nurses need to improve, emphasizing different ways to create a supportive atmosphere that promotes professional development and job satisfaction. To increase nurse retention and promote quality of care, nurse managers need to clarify expectations and guide and support newly qualified nurses in a planned way. © 2013 John Wiley & Sons Ltd.

Kinetic Theory of quasi-electrostatic waves in non-gyrotropic plasmas

NASA Astrophysics Data System (ADS)

Arshad, K.; Poedts, S.; Lazar, M.

2017-12-01

The orbital angular momentum (OAM) is a trait of helically phased light or helical (twisted) electric field. Lasers carrying orbital angular momentum (OAM) revolutionized many scientific and technological paradigms like microscopy, imaging and ionospheric radar facility to analyze three dimensional plasma dynamics in ionosphere, ultra-intense twisted laser pulses, twisted gravitational waves and astrophysics. This trend has also been investigated in plasma physics. Laguerre-Gaussian type solutions are predicted for magnetic tornadoes and Alfvénic tornadoes which exhibit spiral, split and ring-like morphologies. The ring shape morphology is ideal to fit the observed solar corona, solar atmosphere and Earth's ionosphere. The orbital angular momentum indicates the mediation of electrostatic and electromagnetic waves in new phenomena like Raman and Brillouin scattering. A few years ago, some new effects have been included in studies of orbital angular momentum in plasma regimes such as wave-particle interaction in the presence of helical electric field. Therefore, kinetic studies are carried out to investigate the Landau damping of the waves and growth of the instabilities in the presence helical electric field carrying orbital angular momentum for the Maxwellian distributed plasmas. Recently, a well suited approach involving a kappa distribution function has been adopted to model the twisted space plasmas. This leads to the development of new theoretical grounds for the study of Lorentzian or kappa distributed twisted Langmuir, ion acoustic, dust ion acoustic and dust acoustic modes. The quasi-electrostatic twisted waves have been studied now for the non-gyrotropic dusty plasmas in the presence of the orbital angular momentum of the helical electric field using Generalized Lorentzian or kappa distribution function. The Laguerre-Gaussian (LG) mode function is employed to decompose the perturbed distribution function and electric field into planar (longitudinal) and non-planar (azimuthal) components. The modified Vlasov and Poisson equations are solved to obtain the dielectric function for quasi-electrostatic twisted modes the non-gyrotropic dusty plasmas. Some numerical and graphical analysis is also illustrated for the better understanding of the twisted non-gyrotropic plasmas.

Improved Time-Lapsed Angular Scattering Microscopy of Single Cells

NASA Astrophysics Data System (ADS)

Cannaday, Ashley E.

By measuring angular scattering patterns from biological samples and fitting them with a Mie theory model, one can estimate the organelle size distribution within many cells. Quantitative organelle sizing of ensembles of cells using this method has been well established. Our goal is to develop the methodology to extend this approach to the single cell level, measuring the angular scattering at multiple time points and estimating the non-nuclear organelle size distribution parameters. The diameters of individual organelle-size beads were successfully extracted using scattering measurements with a minimum deflection angle of 20 degrees. However, the accuracy of size estimates can be limited by the angular range detected. In particular, simulations by our group suggest that, for cell organelle populations with a broader size distribution, the accuracy of size prediction improves substantially if the minimum angle of detection angle is 15 degrees or less. The system was therefore modified to collect scattering angles down to 10 degrees. To confirm experimentally that size predictions will become more stable when lower scattering angles are detected, initial validations were performed on individual polystyrene beads ranging in diameter from 1 to 5 microns. We found that the lower minimum angle enabled the width of this delta-function size distribution to be predicted more accurately. Scattering patterns were then acquired and analyzed from single mouse squamous cell carcinoma cells at multiple time points. The scattering patterns exhibit angular dependencies that look unlike those of any single sphere size, but are well-fit by a broad distribution of sizes, as expected. To determine the fluctuation level in the estimated size distribution due to measurement imperfections alone, formaldehyde-fixed cells were measured. Subsequent measurements on live (non-fixed) cells revealed an order of magnitude greater fluctuation in the estimated sizes compared to fixed cells. With our improved and better-understood approach to single cell angular scattering, we are now capable of reliably detecting changes in organelle size predictions due to biological causes above our measurement error of 20 nm, which enables us to apply our system to future studies of the investigation of various single cell biological processes.

Professional tennis players' serve: correlation between segmental angular momentums and ball velocity.

PubMed

Martin, Caroline; Kulpa, Richard; Delamarche, Paul; Bideau, Benoit

2013-03-01

The purpose of the study was to identify the relationships between segmental angular momentum and ball velocity between the following events: ball toss, maximal elbow flexion (MEF), racket lowest point (RLP), maximal shoulder external rotation (MER), and ball impact (BI). Ten tennis players performed serves recorded with a real-time motion capture. Mean angular momentums of the trunk, upper arm, forearm, and the hand-racket were calculated. The anteroposterior axis angular momentum of the trunk was significantly related with ball velocity during the MEF-RLP, RLP-MER, and MER-BI phases. The strongest relationships between the transverse-axis angular momentums and ball velocity followed a proximal-to-distal timing sequence that allows the transfer of angular momentum from the trunk (MEF-RLP and RLP-MER phases) to the upper arm (RLP-MER phase), forearm (RLP-MER and MER-BI phases), and the hand-racket (MER-BI phase). Since sequence is crucial for ball velocity, players should increase angular momentums of the trunk during MEF-MER, upper arm during RLP-MER, forearm during RLP-BI, and the hand-racket during MER-BI.

Forming Disc Galaxies In Major Mergers: Radial Density Profiles And Angular Momentum

NASA Astrophysics Data System (ADS)

Peschken, Nicolas; Athanassoula, E.; Rodionov, S. A.; Lambert, J. C.

2017-06-01

In Athanassoula et al. (2016), we used high resolution N-body hydrodynamical simulations to model the major merger between two disc galaxies with a hot gaseous halo each, and showed that the remnant is a spiral galaxy. The two discs are destroyed by the collision, but after the merger, accretion from the surrounding gaseous halo allows the building of a new disc in the remnant galaxy. In Peschken et al. (2017), we used these simulations to study the radial surface density profiles of the remnant galaxies with downbending profiles (type II), i.e. composed of an inner and an outer exponential disc separated by a break. We analyzed the effect of angular momentum on these profiles, and found that the inner and outer disc scalelengths, as well as the break radius, all increase linearly with the total angular momentum of the initial merging system. Following the angular momentum redistribution in our simulations, we find that the disc angular momentum is acquired via accretion from the gaseous halo. Furthermore, high angular momentum systems give more angular momentum to their discs, which affects directly their radial density profile.

A new constitutive analysis of hexagonal close-packed metal in equal channel angular pressing by crystal plasticity finite element method

NASA Astrophysics Data System (ADS)

Li, Hejie; Öchsner, Andreas; Yarlagadda, Prasad K. D. V.; Xiao, Yin; Furushima, Tsuyoshi; Wei, Dongbin; Jiang, Zhengyi; Manabe, Ken-ichi

2018-01-01

Most of hexagonal close-packed (HCP) metals are lightweight metals. With the increasing application of light metal products, the production of light metal is increasingly attracting the attentions of researchers worldwide. To obtain a better understanding of the deformation mechanism of HCP metals (especially for Mg and its alloys), a new constitutive analysis was carried out based on previous research. In this study, combining the theories of strain gradient and continuum mechanics, the equal channel angular pressing process is analyzed and a HCP crystal plasticity constitutive model is developed especially for Mg and its alloys. The influence of elevated temperature on the deformation mechanism of the Mg alloy (slip and twin) is novelly introduced into a crystal plasticity constitutive model. The solution for the new developed constitutive model is established on the basis of the Lagrangian iterations and Newton Raphson simplification.

Statistical theory of correlations in random packings of hard particles.

PubMed

Jin, Yuliang; Puckett, James G; Makse, Hernán A

2014-05-01

A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the n-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom up. A progressive expansion into a shell of particles converges in the large layer limit under a Kirkwood-like approximation of higher-order correlations. We apply the formalism to hard disks and predict the density of two-dimensional random close packing (RCP), ϕ(rcp) = 0.85 ± 0.01, and random loose packing (RLP), ϕ(rlp) = 0.67 ± 0.01. Our theory also predicts a phase diagram and angular correlation functions that are in good agreement with experimental and numerical data.

A pulsed, mono-energetic and angular-selective UV photo-electron source for the commissioning of the KATRIN experiment

NASA Astrophysics Data System (ADS)

Behrens, J.; Ranitzsch, P. C.-O.; Beck, M.; Beglarian, A.; Erhard, M.; Groh, S.; Hannen, V.; Kraus, M.; Ortjohann, H.-W.; Rest, O.; Schlösser, K.; Thümmler, T.; Valerius, K.; Wierman, K.; Wilkerson, J. F.; Winzen, D.; Zacher, M.; Weinheimer, C.

2017-06-01

The KATRIN experiment aims to determine the neutrino mass scale with a sensitivity of 200 {meV/c^2} (90% C. L.) by a precision measurement of the shape of the tritium β -spectrum in the endpoint region. The energy analysis of the decay electrons is achieved by a MAC-E filter spectrometer. To determine the transmission properties of the KATRIN main spectrometer, a mono-energetic and angular-selective electron source has been developed. In preparation for the second commissioning phase of the main spectrometer, a measurement phase was carried out at the KATRIN monitor spectrometer where the device was operated in a MAC-E filter setup for testing. The results of these measurements are compared with simulations using the particle-tracking software "Kassiopeia", which was developed in the KATRIN collaboration over recent years.

Development of a high-precision selenodetic coordinate system for the physical surface of the Moon based on LED beacons on its surface

NASA Astrophysics Data System (ADS)

Shirenin, A. M.; Mazurova, E. M.; Bagrov, A. V.

2016-11-01

The paper presents a mathematical algorithm for processing an array of angular measurements of light beacons on images of the lunar surface onboard a polar artificial lunar satellite (PALS) during the Luna-Glob mission and coordinate-time referencing of the PALS for the development of reference selenocentric coordinate systems. The algorithm makes it possible to obtain angular positions of point light beacons located on the surface of the Moon in selenocentric celestial coordinates. The operation of measurement systems that determine the position and orientation of the PALS during its active existence have been numerically simulated. Recommendations have been made for the optimal use of different types of measurements, including ground radio trajectory measurements, navigational star sensors based on the onboard star catalog, gyroscopic orientation systems, and space videos of the lunar surface.

Deformable complex network for refining low-resolution X-ray structures

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

Zhang, Chong; Wang, Qinghua; Ma, Jianpeng, E-mail: jpma@bcm.edu

2015-10-27

A new refinement algorithm called the deformable complex network that combines a novel angular network-based restraint with a deformable elastic network model in the target function has been developed to aid in structural refinement in macromolecular X-ray crystallography. In macromolecular X-ray crystallography, building more accurate atomic models based on lower resolution experimental diffraction data remains a great challenge. Previous studies have used a deformable elastic network (DEN) model to aid in low-resolution structural refinement. In this study, the development of a new refinement algorithm called the deformable complex network (DCN) is reported that combines a novel angular network-based restraint withmore » the DEN model in the target function. Testing of DCN on a wide range of low-resolution structures demonstrated that it constantly leads to significantly improved structural models as judged by multiple refinement criteria, thus representing a new effective refinement tool for low-resolution structural determination.« less

Development of esMOCA RULA, Motion Capture Instrumentation for RULA Assessment

NASA Astrophysics Data System (ADS)

Akhmad, S.; Arendra, A.

2018-01-01

The purpose of this research is to build motion capture instrumentation using sensors fusion accelerometer and gyroscope to assist in RULA assessment. Data processing of sensor orientation is done in every sensor node by digital motion processor. Nine sensors are placed in the upper limb of operator subject. Development of kinematics model is done with Simmechanic Simulink. This kinematics model receives streaming data from sensors via wireless sensors network. The output of the kinematics model is the relative angular angle between upper limb members and visualized on the monitor. This angular information is compared to the look-up table of the RULA worksheet and gives the RULA score. The assessment result of the instrument is compared with the result of the assessment by rula assessors. To sum up, there is no significant difference of assessment by the instrument with an assessment by an assessor.

Next Generation X-Ray Optics: High-Resolution, Light-Weight, and Low-Cost

NASA Technical Reports Server (NTRS)

Zhang, William W.

2012-01-01

X-ray telescopes are essential to the future of x-ray astronomy. In this talk I will describe a comprehensive program to advance the technology for x-ray telescopes well beyond the state of the art represented by the three currently operating missions: Chandra, XMM-Newton, and Suzaku. This program will address the three key issues in making an x-ray telescope: (1) angular resolution, (2) effective area per unit mass, and (3) cost per unit effective area. The objectives of this technology program are (1) in the near term, to enable Explorer-class x-ray missions and an IXO-type mission, and (2) in the long term, to enable a flagship x-ray mission with sub-arcsecond angular resolution and multi-square-meter effective area, at an affordable cost. We pursue two approaches concurrently, emphasizing the first approach in the near term (2-5 years) and the second in the long term (4-10 years). The first approach is precision slumping of borosilicate glass sheets. By design and choice at the outset, this technique makes lightweight and low-cost mirrors. The development program will continue to improve angular resolution, to enable the production of 5-arcsecond x-ray telescopes, to support Explorer-class missions and one or more missions to supersede the original IXO mission. The second approach is precision polishing and light-weighting of single-crystal silicon mirrors. This approach benefits from two recent commercial developments: (1) the inexpensive and abundant availability of large blocks of monocrystalline silicon, and (2) revolutionary advances in deterministic, precision polishing of mirrors. By design and choice at the outset, this technique is capable of producing lightweight mirrors with sub-arcsecond angular resolution. The development program will increase the efficiency and reduce the cost of the polishing and the light-weighting processes, to enable the production of lightweight sub-arcsecond x-ray telescopes. Concurrent with the fabrication of lightweight mirror segments is the continued development and perfection of alignment and integration techniques, for incorporating individual mirror segments into a precision mirror assembly. Recently, we have been developing a technique called edge-bonding, which has achieved an accuracy to enable 10-arcsecond x-ray telescopes. Currently, we are investigating and improving the long-term alignment stability of so-bonded mirrors. Next, we shall refine this process to enable 5-arsecond x-ray telescopes. This technology development program includes all elements to demonstrate progress toward TRL-6: metrology; x-ray performance tests; coupled structural, thermal, and optical performance analysis, and environmental testing.

Next Generation X-Ray Optics: High-Resolution, Light-Weight, and Low-Cost

NASA Technical Reports Server (NTRS)

Zhang, William W.

2011-01-01

X-ray telescopes are essential to the future of x-ray astronomy. This paper describes a comprehensive program to advance the technology for x-ray telescopes well beyond the state of the art represented by the three currently operating missions: Chandra, XMM-Newton , and Suzaku . This program will address the three key issues in making an x-ray telescope: (I) angular resolution, (2) effective area per unit mass, and (3) cost per unit effective area. The objectives of this technology program are (1) in the near term, to enable Explorer-class x-ray missions and an IXO type mission, and (2) in the long term, to enable a flagship x-ray mission with sub-arcsecond angular resolution and multi-square-meter effective area, at an affordable cost. We pursue two approaches concurrently, emphasizing the first approach in the near term (2-5 years) and the second in the long term (4-10 years). The first approach is precision slumping of borosilicate glass sheets. By design and choice at the outset, this technique makes lightweight and low-cost mirrors. The development program will continue to improve angular resolution, to enable the production of 5-arcsecond x-ray telescopes, to support Explorer-class missions and one or more missions to supersede the original IXO mission. The second approach is precision polishing and light-weighting of single-crystal silicon mirrors. This approach benefits from two recent commercial developments: (1) the inexpensive and abundant availability of large blocks of mono crystalline silicon, and (2) revolutionary advances in deterministic, precision polishing of mirrors. By design and choice at the outset, this technique is capable of producing lightweight mirrors with sub-arcsecond angular resolution. The development program will increase the efficiency and reduce the cost of the polishing and the lightweighting processes, to enable the production of lightweight sub-arcsecond x-ray telescopes. Concurrent with the fabrication of lightweight mirror segments is the continued development and perfection of alignment and integration techniques, for incorporating individual mirror segments into a precision mirror assembly. Recently, we have been developing a technique called edge-bonding, which has achieved an accuracy to enable 10- arcsecond x-ray telescopes. Currently, we are investigating and improving the long-term alignment stability of so-bonded mirrors. Next, we shall refine this process to enable 5-arsecond x-ray telescopes. This technology development program includes all elements to demonstrate progress toward TRL-6: metrology; x-ray performance tests; coupled structural, thermal, and optical performance analysis, and environmental testing.

Stressors of newly graduated nurses in Shanghai paediatric hospital: a qualitative study.

PubMed

Hu, Yun; Zhang, Yaqing; Shen, Nanping; Wu, Juemin; Wu, Jia; Malmedal, Wenche K

2017-04-01

To identify stressors of newly graduated paediatric nurses at a children's hospital in Shanghai, China. Stress is an international phenomenon in nursing generally, but little is known about its effect on new paediatric nurses at the Shanghai paediatric hospital. Participants in this research were 25 newly graduated paediatric nurses. Their behaviours and perceptions were explored by field observations and interviews. Findings indicated that participants experienced numerous stressors: low work status, insufficient professional competence, heavy workload, inadequate supportive systems and uncertainty of career development. The results of the present study provide useful information for administrators to develop and improve postgraduate programmes to support novice paediatric nurses. Our research highlights the importance of identifying the stressors of new paediatric nurses in the light of a serious nurse shortage and an increasing birth rate. © 2016 John Wiley & Sons Ltd.

Effects of aggregate angularity on mix design characteristics and pavement performance.

DOT National Transportation Integrated Search

2009-12-01

This research targeted two primary purposes: to estimate current aggregate angularity test methods and to evaluate current : aggregate angularity requirements in the Nebraska asphalt mixture/pavement specification. To meet the first research : object...

Thermal Ion Upwelling in the High-Altitude Ionosphere

DTIC Science & Technology

1990-01-01

hard sphere collisions) while Vst is the momentum transfer collision frequency between all the other species t and a single s species particle. For... angular dimensions of day side entrance region off of Od degrees towards evening Od angular dimensions of day side entrance region off of 0d...degrees towards morning + angular dimensions of night side exit region off of on towards degrees On degre morning On angular dimensions of night side exit

Angular width of the Cherenkov radiation with inclusion of multiple scattering

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

Zheng, Jian, E-mail: jzheng@ustc.edu.cn

2016-06-15

Visible Cherenkov radiation can offer a method of the measurement of the velocity of charged particles. The angular width of the radiation is important since it determines the resolution of the velocity measurement. In this article, the angular width of Cherenkov radiation with inclusion of multiple scattering is calculated through the path-integral method, and the analytical expressions are presented. The condition that multiple scattering processes dominate the angular distribution is obtained.

Interpreting angular momentum transfer between electromagnetic multipoles using vector spherical harmonics.

PubMed

Grinter, Roger; Jones, Garth A

2018-02-01

The transfer of angular momentum between a quadrupole emitter and a dipole acceptor is investigated theoretically. Vector spherical harmonics are used to describe the angular part of the field of the mediating photon. Analytical results are presented for predicting angular momentum transfer between the emitter and absorber within a quantum electrodynamical framework. We interpret the allowability of such a process, which appears to violate conservation of angular momentum, in terms of the breakdown of the isotropy of space at the point of photon absorption (detection). That is, collapse of the wavefunction results in loss of all angular momentum information. This is consistent with Noether's Theorem and demystifies some common misconceptions about the nature of the photon. The results have implications for interpreting the detection of photons from multipole sources and offers insight into limits on information that can be extracted from quantum measurements in photonic systems.

Creating high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses

NASA Astrophysics Data System (ADS)

Xin, PeiPei; Cheng, Hong; Zhang, ShanShan; Wang, HanMu; Xu, ZiShan; Liu, HongPing

2018-04-01

We propose a method of producing high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses. The first positive-polarity optical half-cycle pulse is used to prepare an excited-state wave packet while the second one is less intense, but with opposite polarity and time delayed, and is employed to drag back the escaping free electron and clip the shape of the bound Rydberg wave packet, selectively increasing or decreasing a fraction of the angular-momentum components. An intelligent choice of laser parameters such as phase and amplitude helps us to control the orbital-angular-momentum composition of an electron wave packet with more facility; thus, a specified angular-momentum state with high purity can be achieved. This scheme of producing high-purity angular-momentum-state Rydberg atoms has significant application in quantum-information processing.

Angular momentum conservation law in light-front quantum field theory

DOE PAGES

Chiu, Kelly Yu-Ju; Brodsky, Stanley J.

2017-03-31

We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3, the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QED andmore » QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.« less

Aliasing Detection and Reduction Scheme on Angularly Undersampled Light Fields.

PubMed

Xiao, Zhaolin; Wang, Qing; Zhou, Guoqing; Yu, Jingyi

2017-05-01

When using plenoptic camera for digital refocusing, angular undersampling can cause severe (angular) aliasing artifacts. Previous approaches have focused on avoiding aliasing by pre-processing the acquired light field via prefiltering, demosaicing, reparameterization, and so on. In this paper, we present a different solution that first detects and then removes angular aliasing at the light field refocusing stage. Different from previous frequency domain aliasing analysis, we carry out a spatial domain analysis to reveal whether the angular aliasing would occur and uncover where in the image it would occur. The spatial analysis also facilitates easy separation of the aliasing versus non-aliasing regions and angular aliasing removal. Experiments on both synthetic scene and real light field data sets (camera array and Lytro camera) demonstrate that our approach has a number of advantages over the classical prefiltering and depth-dependent light field rendering techniques.

Gait event detection using linear accelerometers or angular velocity transducers in able-bodied and spinal-cord injured individuals.

PubMed

Jasiewicz, Jan M; Allum, John H J; Middleton, James W; Barriskill, Andrew; Condie, Peter; Purcell, Brendan; Li, Raymond Che Tin

2006-12-01

We report on three different methods of gait event detection (toe-off and heel strike) using miniature linear accelerometers and angular velocity transducers in comparison to using standard pressure-sensitive foot switches. Detection was performed with normal and spinal-cord injured subjects. The detection of end contact (EC), normally toe-off, and initial contact (IC) normally, heel strike was based on either foot linear accelerations or foot sagittal angular velocity or shank sagittal angular velocity. The results showed that all three methods were as accurate as foot switches in estimating times of IC and EC for normal gait patterns. In spinal-cord injured subjects, shank angular velocity was significantly less accurate (p<0.02). We conclude that detection based on foot linear accelerations or foot angular velocity can correctly identify the timing of IC and EC events in both normal and spinal-cord injured subjects.

Angular momentum conservation law in light-front quantum field theory

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

Chiu, Kelly Yu-Ju; Brodsky, Stanley J.

We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3, the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QED andmore » QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.« less

Angular momentum conservation law in light-front quantum field theory

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

Chiu, Kelly Yu-Ju; Brodsky, Stanley J.

We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3 , the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QEDmore » and QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.« less

Light's Darkness

ScienceCinema

Padgett, Miles [University of Glasgow, Glasgow, Scotland

2017-12-09

Optical vortices and orbital angular momentum are currently topical subjects in the optics literature. Although seemingly esoteric, they are, in fact, the generic state of light and arise whenever three or more plane waves interfere. To be observed by eye the light must be monochromatic. Laser speckle is one such example, where the optical energy circulates around each black spot, giving a local orbital angular momentum. This talk with report three on-going studies. First, when considering a volume of interfering waves, the laser specs map out threads of complete darkness embedded in the light. Do these threads form loops? Links? Or even knots? Second, when looking through a rapidly spinning window, the image of the world on the other side is rotated: true or false? Finally, the entanglement of orbital angular momentum states means measuring how the angular position of one photons sets the angular momentum of another: is this an angular version of the EPR (Einstein, Podolsky, and Rosen) paradox?