Application of carbon nanotubes to topographical resolution enhancement of tapered fiber scanning near field optical microscopy probes

NASA Astrophysics Data System (ADS)

Huntington, S. T.; Jarvis, S. P.

2003-05-01

Scanning near field optical microscopy (SNOM) probes are typically tapered optical fibers with metallic coatings. The tip diameters are generally in excess of 300 nm and thus provide poor topographical resolution. Here we report on the attachment multiwalled carbon nanotubes to the probes in order to substantially enhance the topographical resolution, without adversely affecting the optical resolution.

Optimization of auxiliary optics in active-optics telescopes

NASA Astrophysics Data System (ADS)

Ragazzoni, Roberto

1993-04-01

The a-priori knowledge of the availability of active optics in a telescope can be advantageous in the design, optimization, and specification of tolerances for auxiliary devices of such a telescope. A modification of the merit function to be used into the optimization process is given, together with some considerations about the design procedure. The different effects of aberrations typically depending upon the position of the field of view (like coma or astigmatism), with those typically constant over the whole field of view (like spherical aberration) are explicitly taken into account in the mathematical treatment. A possible range of applications (prime focus corrector, off-axis field corrector, field flattener, reducing camera, and so on) is discussed. A case study for a field flattener is shown. The general result that can be derived from this paper is that tolerances are generally strongly relaxed, while a significant improvement of the nominal performances can be obtained only in particular cases or assuming a high dynamic range of the active optics correction.

A new class of monolithic seismometers and accelerometers for commercial and industrial applications: the UNISA folded pendulum

NASA Astrophysics Data System (ADS)

Barone, F.; Giordano, G.

2017-04-01

In this paper we present monolithic implementations of tunable mechanical seismometers and accelerometers (horizontal, vertical and angular) based on the UNISA Folded Pendulum configuration, protected by three international patents and commercially available. Typical characteristics are measurement band 10-7 / 1kHz, sensitivity down to ≍ 10-15 m/ √ Hz, directivity > 104, weight < 1.5 kg, dimensions < 10 cm, coupled to a large insensitivity to environmental noises and capability of operating in ultra high vacuum and cryogenic environments. Typical applications of this class of sensors are in the field of earthquake engineering, seismology, geophysics, civil engineering (buildings, bridges, dams, etc.), space (inertial guide).

Rare earth fluoride nano-/microstructures: hydrothermal synthesis, luminescent properties and applications.

PubMed

Zhao, Qian; Xu, Zhenhe; Sun, Yaguang

2014-02-01

Rare earth fluoride materials have attracted wide interest and come to the forefront in nanophotonics due to their distinct electrical, optical and magnetic properties as well as their potential applications in diverse fields such as optical telecommunication, lasers, biochemical probes, infrared quantum counters, and medical diagnostics. This review presents a comprehensive overview of the flourishing field of rare earth fluorides materials in the past decade. We summarize the recent research progress on the preparation, morphology, luminescent properties and application of rare earth fluoride-based luminescent materials by hydrothermal systems. Various rare earth fluoride materials are obtained by fine-tuning of experimental conditions, such as capping agents, fluoride source, acidity, temperature and reaction time. The controlled morphology, luminescent properties and application of the rare earth fluorides are briefly discussed with typical examples.

Polarimetric ISAR: Simulation and image reconstruction

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

Chambers, David H.

In polarimetric ISAR the illumination platform, typically airborne, carries a pair of antennas that are directed toward a fixed point on the surface as the platform moves. During platform motion, the antennas maintain their gaze on the point, creating an effective aperture for imaging any targets near that point. The interaction between the transmitted fields and targets (e.g. ships) is complicated since the targets are typically many wavelengths in size. Calculation of the field scattered from the target typically requires solving Maxwell’s equations on a large three-dimensional numerical grid. This is prohibitive to use in any real-world imaging algorithm, somore » the scattering process is typically simplified by assuming the target consists of a cloud of independent, non-interacting, scattering points (centers). Imaging algorithms based on this scattering model perform well in many applications. Since polarimetric radar is not very common, the scattering model is often derived for a scalar field (single polarization) where the individual scatterers are assumed to be small spheres. However, when polarization is important, we must generalize the model to explicitly account for the vector nature of the electromagnetic fields and its interaction with objects. In this note, we present a scattering model that explicitly includes the vector nature of the fields but retains the assumption that the individual scatterers are small. The response of the scatterers is described by electric and magnetic dipole moments induced by the incident fields. We show that the received voltages in the antennas are linearly related to the transmitting currents through a scattering impedance matrix that depends on the overall geometry of the problem and the nature of the scatterers.« less

Contamination characteristics and degradation behavior of low-density polyethylene film residues in typical farmland soils of China.

PubMed

Xu, Gang; Wang, Qunhui; Gu, Qingbao; Cao, Yunzhe; DU, Xiaoming; Li, Fasheng

2006-01-01

Low-density polyethylene (LDPE) film residues left in farmlands due to agricultural activities were extensively investigated to evaluate the present pollution situation by selecting the typical areas with LDPE film application, including Harbin, Baoding, and Handan of China. The survey results demonstrated that the film residues were ubiquitous within the investigated areas and the amount reached 2,400-8,200 g ha(-1). Breakage rates of the film residues were almost at the same level in the studied fields. There were relatively small amounts of film residues remaining in neighboring farmland fields without application of LDPE film. The studies showed that the sheets of LDPE residues had the same oxidative deterioration, which was probably due to photodegradation instead of biodegradation. The higher molecular weight components of the LDPE film gradually decreased, which were reflected by the appearance of some small flakes detached from the film bodies. LDPE films in the investigated fields gradually deteriorated and the decomposing levels developed with their left time increasing. The degradation behaviors of LDPE films were confirmed by using Fourier transform infrared (FTIR), scanning electron microscopic (SEM), and gel permeation chromatography analyses.

Doppler-shifted fluorescence imaging of velocity fields in supersonic reacting flows

NASA Technical Reports Server (NTRS)

Allen, M. G.; Davis, S. J.; Kessler, W. J.; Sonnenfroh, D. M.

1992-01-01

The application of Doppler-shifted fluorescence imaging of velocity fields in supersonic reacting flows is analyzed. Focussing on fluorescence of the OH molecule in typical H2-air Scramjet flows, the effects of uncharacterized variations in temperature, pressure, and collisional partner composition across the measurement plane are examined. Detailed measurements of the (1,0) band OH lineshape variations in H2-air combustions are used, along with single-pulse and time-averaged measurements of an excimer-pumped dye laser, to predict the performance of a model velocimeter with typical Scramjet flow properties. The analysis demonstrates the need for modification and control of the laser bandshape in order to permit accurate velocity measurements in the presence of multivariant flow properties.

East-West paths to unconventional computing.

PubMed

Adamatzky, Andrew; Akl, Selim; Burgin, Mark; Calude, Cristian S; Costa, José Félix; Dehshibi, Mohammad Mahdi; Gunji, Yukio-Pegio; Konkoli, Zoran; MacLennan, Bruce; Marchal, Bruno; Margenstern, Maurice; Martínez, Genaro J; Mayne, Richard; Morita, Kenichi; Schumann, Andrew; Sergeyev, Yaroslav D; Sirakoulis, Georgios Ch; Stepney, Susan; Svozil, Karl; Zenil, Hector

2017-12-01

Unconventional computing is about breaking boundaries in thinking, acting and computing. Typical topics of this non-typical field include, but are not limited to physics of computation, non-classical logics, new complexity measures, novel hardware, mechanical, chemical and quantum computing. Unconventional computing encourages a new style of thinking while practical applications are obtained from uncovering and exploiting principles and mechanisms of information processing in and functional properties of, physical, chemical and living systems; in particular, efficient algorithms are developed, (almost) optimal architectures are designed and working prototypes of future computing devices are manufactured. This article includes idiosyncratic accounts of 'unconventional computing' scientists reflecting on their personal experiences, what attracted them to the field, their inspirations and discoveries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Technical Challenges and Solutions in Representing Lakes when using WRF in Downscaling Applications

EPA Science Inventory

The Weather Research and Forecasting (WRF) model is commonly used to make high resolution future projections of regional climate by downscaling global climate model (GCM) outputs. Because the GCM fields are typically at a much coarser spatial resolution than the target regional ...

Performance characterization of a combined material identification and screening algorithm

NASA Astrophysics Data System (ADS)

Green, Robert L.; Hargreaves, Michael D.; Gardner, Craig M.

2013-05-01

Portable analytical devices based on a gamut of technologies (Infrared, Raman, X-Ray Fluorescence, Mass Spectrometry, etc.) are now widely available. These tools have seen increasing adoption for field-based assessment by diverse users including military, emergency response, and law enforcement. Frequently, end-users of portable devices are non-scientists who rely on embedded software and the associated algorithms to convert collected data into actionable information. Two classes of problems commonly encountered in field applications are identification and screening. Identification algorithms are designed to scour a library of known materials and determine whether the unknown measurement is consistent with a stored response (or combination of stored responses). Such algorithms can be used to identify a material from many thousands of possible candidates. Screening algorithms evaluate whether at least a subset of features in an unknown measurement correspond to one or more specific substances of interest and are typically configured to detect from a small list potential target analytes. Thus, screening algorithms are much less broadly applicable than identification algorithms; however, they typically provide higher detection rates which makes them attractive for specific applications such as chemical warfare agent or narcotics detection. This paper will present an overview and performance characterization of a combined identification/screening algorithm that has recently been developed. It will be shown that the combined algorithm provides enhanced detection capability more typical of screening algorithms while maintaining a broad identification capability. Additionally, we will highlight how this approach can enable users to incorporate situational awareness during a response.

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

Schreiber, J.; Max-Planck-Institut für Quantenoptik Garching, Hans-Kopfermann-Str. 1, 85748 Garching bei München; Bolton, P. R.

An overview of progress and typical yields from intense laser-plasma acceleration of ions is presented. The evolution of laser-driven ion acceleration at relativistic intensities ushers prospects for improved functionality and diverse applications which can represent a varied assortment of ion beam requirements. This mandates the development of the integrated laser-driven ion accelerator system, the multiple components of which are described. Relevant high field laser-plasma science and design of controlled optimum pulsed laser irradiation on target are dominant single shot (pulse) considerations with aspects that are appropriate to the emerging petawatt era. The pulse energy scaling of maximum ion energies andmore » typical differential spectra obtained over the past two decades provide guidance for continued advancement of laser-driven energetic ion sources and their meaningful applications.« less

Spherical Rare-Earth Magnets in Introductory Physics

ERIC Educational Resources Information Center

Adams, Al

2007-01-01

Permanent magnets have long been used in both traditional laboratory exercises and in inquiry-based learning activities. These pedagogical applications are typically timed to correspond to the early coverage of magnetism in the second-semester sequence of introductory physics. At the initial level the concepts relate to the magnetic field of the…

The new structure and contents of employers' juridical responsibility for workers' health and safety in the post-industrial system.

PubMed

Ichino, P

2006-01-01

1. The enlargement of the labour law application area in the post-industrial system. 2. The enormous growth of differences in productivity between workers and its consequences on the employer's safety obligation. 3. Depressive disorders as a typical professional risk in the post-industrial system and the employer's prevention responsibility. 4. Harassment in the work-place as a typical pathologic consequence of the de-standardization of jobs. The specific employer's prevention responsibility in this field. 5. A conclusive remark.

Chaos of energetic positron orbits in a dipole magnetic field and its potential application to a new injection scheme

NASA Astrophysics Data System (ADS)

Saitoh, H.; Yoshida, Z.; Yano, Y.; Nishiura, M.; Kawazura, Y.; Horn-Stanja, J.; Pedersen, T. Sunn

2016-10-01

We study the behavior of high-energy positrons emitted from a radioactive source in a magnetospheric dipole field configuration. Because the conservation of the first and second adiabatic invariants is easily destroyed in a strongly inhomogeneous dipole field for high-energy charged particles, the positron orbits are nonintegrable, resulting in chaotic motions. In the geometry of a typical magnetospheric levitated dipole experiment, it is shown that a considerable ratio of positrons from a 22Na source, located at the edge of the confinement region, has chaotic long orbit lengths before annihilation. These particles make multiple toroidal circulations and form a hollow toroidal positron cloud. Experiments with a small 22Na source in the Ring Trap 1 (RT-1) device demonstrated the existence of such long-lived positrons in a dipole field. Such a chaotic behavior of high-energy particles is potentially applicable to the formation of a dense toroidal positron cloud in the strong-field region of the dipole field in future studies.

Mitigating reentry radio blackout by using a traveling magnetic field

NASA Astrophysics Data System (ADS)

Zhou, Hui; Li, Xiaoping; Xie, Kai; Liu, Yanming; Yu, Yuanyuan

2017-10-01

A hypersonic flight or a reentry vehicle is surrounded by a plasma layer that prevents electromagnetic wave transmission, which results in radio blackout. The magnetic-window method is considered a promising means to mitigate reentry communication blackout. However, the real application of this method is limited because of the need for strong magnetic fields. To reduce the required magnetic field strength, a novel method that applies a traveling magnetic field (TMF) is proposed in this study. A mathematical model based on magneto-hydrodynamic theory is adopted to analyze the effect of TMF on plasma. The mitigating effects of the TMF on the blackout of typical frequency bands, including L-, S-, and C-bands, are demonstrated. Results indicate that a significant reduction of plasma density occurs in the magnetic-window region by applying a TMF, and the reduction ratio is positively correlated with the velocity of the TMF. The required traveling velocities for eliminating the blackout of the Global Positioning System (GPS) and the typical telemetry system are also discussed. Compared with the constant magnetic-window method, the TMF method needs lower magnetic field strength and is easier to realize in the engineering field.

Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

NASA Astrophysics Data System (ADS)

Lipkens, Bart; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.

2015-10-01

Ultrasonic standing waves are widely used for separation applications. In MEMS applications, a half wavelength standing wave field is generated perpendicular to a laminar flow. The acoustic radiation force exerted on the particle drives the particle to the center of the MEMS channel, where concentrated particles are harvested. In macro-scale applications, the ultrasonic standing wave spans multiple wavelengths. Examples of such applications are oil/water emulsion splitting [1], and blood/lipid separation [2]. In macro-scale applications, particles are typically trapped in the standing wave, resulting in clumping or coalescence of particles/droplets. Subsequent gravitational settling results in separation of the secondary phase. An often used expression for the radiation force on a particle is that derived by Gorkov [3]. The assumptions are that the particle size is small relative to the wavelength, and therefore, only monopole and dipole scattering contributions are used to calculate the radiation force. This framework seems satisfactory for MEMS scale applications where each particle is treated separately by the standing wave, and concentrations are typically low. In macro-scale applications, particle concentration is high, and particle clumping or droplet coalescence results in particle sizes not necessarily small relative to the wavelength. Ilinskii et al. developed a framework for calculation of the acoustic radiation force valid for any size particle [4]. However, this model does not take into account particle to particle effects, which can become important as particle concentration increases. It is known that an acoustic radiation force on a particle or a droplet is determined by the local field. An acoustic radiation force expression is developed that includes the effect of particle to particle interaction. The case of two neighboring particles is considered. The approach is based on sound scattering by the particles. The acoustic field at the location of one particle then consists of two components, the incident sound wave and the scattered field generated by the neighboring particle. The radiation force calculation then includes the contributions of these two fields and incorporates the mutual particle influence. In this investigation the droplet/particle influence on each other has been analyzed theoretically by using the method developed by Gorkov and modified by Ilinskii et al.

Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

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

Lipkens, Bart, E-mail: blipkens@wne.edu; Ilinskii, Yurii A., E-mail: ilinskii@gmail.com; Zabolotskaya, Evgenia A., E-mail: zheniazabolotskaya@gmail.com

Ultrasonic standing waves are widely used for separation applications. In MEMS applications, a half wavelength standing wave field is generated perpendicular to a laminar flow. The acoustic radiation force exerted on the particle drives the particle to the center of the MEMS channel, where concentrated particles are harvested. In macro-scale applications, the ultrasonic standing wave spans multiple wavelengths. Examples of such applications are oil/water emulsion splitting [1], and blood/lipid separation [2]. In macro-scale applications, particles are typically trapped in the standing wave, resulting in clumping or coalescence of particles/droplets. Subsequent gravitational settling results in separation of the secondary phase. Anmore » often used expression for the radiation force on a particle is that derived by Gorkov [3]. The assumptions are that the particle size is small relative to the wavelength, and therefore, only monopole and dipole scattering contributions are used to calculate the radiation force. This framework seems satisfactory for MEMS scale applications where each particle is treated separately by the standing wave, and concentrations are typically low. In macro-scale applications, particle concentration is high, and particle clumping or droplet coalescence results in particle sizes not necessarily small relative to the wavelength. Ilinskii et al. developed a framework for calculation of the acoustic radiation force valid for any size particle [4]. However, this model does not take into account particle to particle effects, which can become important as particle concentration increases. It is known that an acoustic radiation force on a particle or a droplet is determined by the local field. An acoustic radiation force expression is developed that includes the effect of particle to particle interaction. The case of two neighboring particles is considered. The approach is based on sound scattering by the particles. The acoustic field at the location of one particle then consists of two components, the incident sound wave and the scattered field generated by the neighboring particle. The radiation force calculation then includes the contributions of these two fields and incorporates the mutual particle influence. In this investigation the droplet/particle influence on each other has been analyzed theoretically by using the method developed by Gorkov and modified by Ilinskii et al.« less

Radiometric calibration of wide-field camera system with an application in astronomy

NASA Astrophysics Data System (ADS)

Vítek, Stanislav; Nasyrova, Maria; Stehlíková, Veronika

2017-09-01

Camera response function (CRF) is widely used for the description of the relationship between scene radiance and image brightness. Most common application of CRF is High Dynamic Range (HDR) reconstruction of the radiance maps of imaged scenes from a set of frames with different exposures. The main goal of this work is to provide an overview of CRF estimation algorithms and compare their outputs with results obtained under laboratory conditions. These algorithms, typically designed for multimedia content, are unfortunately quite useless with astronomical image data, mostly due to their nature (blur, noise, and long exposures). Therefore, we propose an optimization of selected methods to use in an astronomical imaging application. Results are experimentally verified on the wide-field camera system using Digital Single Lens Reflex (DSLR) camera.

Exposure assessment procedures in presence of wideband digital wireless networks.

PubMed

Trinchero, D

2009-12-01

The article analyses the applicability of traditional methods, as well as recently proposed techniques, to the exposure assessment of electromagnetic field generated by wireless transmitters. As is well known, a correct measurement of the electromagnetic field is conditioned by the complexity of the signal, which requires dedicated instruments or specifically developed extrapolation techniques. Nevertheless, it is also influenced by the typology of the deployment of the transmitting and receiving stations, which varies from network to network. These aspects have been intensively analysed in the literature and several cases of study are available for review. The present article collects the most recent analyses and discusses their applicability to different scenarios, typical of the main wireless networking applications: broadcasting services, mobile cellular networks and data access provisioning infrastructures.

Investigation on cone jetting regimes of liquid droplets subjected to pyroelectric fields induced by laser blasts

NASA Astrophysics Data System (ADS)

Gennari, Oriella; Battista, Luigi; Silva, Benjamin; Grilli, Simonetta; Miccio, Lisa; Vespini, Veronica; Coppola, Sara; Orlando, Pierangelo; Aprin, Laurent; Slangen, Pierre; Ferraro, Pietro

2015-02-01

Electrical conductivity and viscosity play a major role in the tip jetting behaviour of liquids subjected to electrohydrodynamic (EHD) forces, thus influencing significantly the printing performance. Recently, we developed a nozzle- and electrode-free pyro-EHD system as a versatile alternative to conventional EHD configurations and we demonstrated different applications, including inkjet printing and three-dimensional lithography. However, only dielectric fluids have been used in all of those applications. Here, we present an experimental characterization of the pyro-EHD jetting regimes, induced by laser blasts, of sessile drops in case of dielectric and conductive liquids in order to extend the applicability of the system to a wider variety of fields including biochemistry and biotechnology where conductive aqueous solutions are typically used.

Surface vertical magnetic field produced by a finite loop buried in an earth containing a thin conducting sheet

NASA Astrophysics Data System (ADS)

Durkin, John

1997-01-01

The effect of a thin conducting sheet located at the earth-to-air interface on the surface vertical magnetic field created by a buried finite loop was studied. Expected field values as a function of frequency are provided for variations in the sheet's conductivity-thickness product. Since the results would be most beneficial for purposes of through-the-earth communications, such as communicating with trapped miners following a mine emergency, field values were derived for a range of frequencies, mine depths, and earth conductivity values that would be typically found in such an application.

CPFP Summer Curriculum: Principles and Practices of Cancer Prevention and Control Course | Division of Cancer Prevention

Cancer.gov

This Cancer Prevention Fellowship Program four-week summer course provides specialized instruction in the principles and practice of cancer prevention and control. Participants will gain a broad-based perspective on concepts, issues, and applications related to this field. The course typically covers the following topics: |

Life Story Reflection in Social Work Education: A Practical Model

ERIC Educational Resources Information Center

Spector-Mersel, Gabriela

2017-01-01

Drawing from the practice-oriented conception of reflection in social work, its applications in social work education typically focus on students' encounters with the field. Recognizing the value of practice-oriented reflection yet aware of its limitations, complementing it with life story reflection (LSR) is urged. The importance of LSR in social…

Hyperbolic metamaterials: Novel physics and applications

NASA Astrophysics Data System (ADS)

Smolyaninov, Igor I.; Smolyaninova, Vera N.

2017-10-01

Hyperbolic metamaterials were originally introduced to overcome the diffraction limit of optical imaging. Soon thereafter it was realized that hyperbolic metamaterials demonstrate a number of novel phenomena resulting from the broadband singular behavior of their density of photonic states. These novel phenomena and applications include super resolution imaging, new stealth technologies, enhanced quantum-electrodynamic effects, thermal hyperconductivity, superconductivity, and interesting gravitation theory analogues. Here we briefly review typical material systems, which exhibit hyperbolic behavior and outline important novel applications of hyperbolic metamaterials. In particular, we will describe recent imaging experiments with plasmonic metamaterials and novel VCSEL geometries, in which the Bragg mirrors may be engineered in such a way that they exhibit hyperbolic metamaterial properties in the long wavelength infrared range, so that they may be used to efficiently remove excess heat from the laser cavity. We will also discuss potential applications of three-dimensional self-assembled photonic hypercrystals, which are based on cobalt ferrofluids in external magnetic field. This system bypasses 3D nanofabrication issues, which typically limit metamaterial applications. Photonic hypercrystals combine the most interesting features of hyperbolic metamaterials and photonic crystals.

Quasi-conformal remapping for compensation of human visual field defects - Advances in image remapping for human field defects

NASA Technical Reports Server (NTRS)

Juday, Richard D.; Loshin, David S.

1989-01-01

Image coordinate transformations are investigated for possible use in a low vision aid for human patients. These patients typically have field defects with localized retinal dysfunction predominately central (age related maculopathy) or peripheral (retinitis pigmentosa). Previously simple eccentricity-only remappings which do not maintain conformality were shown. Initial attempts on developing images which hold quasi-conformality after remapping are presented. Although the quasi-conformal images may have less local distortion, there are discontinuities in the image which may counterindicate this type of transformation for the low vision application.

A texture-based framework for improving CFD data visualization in a virtual environment

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

Bivins, Gerrick O'Ron

2005-01-01

In the field of computational fluid dynamics (CFD) accurate representations of fluid phenomena can be simulated hut require large amounts of data to represent the flow domain. Most datasets generated from a CFD simulation can be coarse, ~10,000 nodes or cells, or very fine with node counts on the order of 1,000,000. A typical dataset solution can also contain multiple solutions for each node, pertaining to various properties of the flow at a particular node. Scalar properties such as density, temperature, pressure, and velocity magnitude are properties that are typically calculated and stored in a dataset solution. Solutions are notmore » limited to just scalar properties. Vector quantities, such as velocity, are also often calculated and stored for a CFD simulation. Accessing all of this data efficiently during runtime is a key problem for visualization in an interactive application. Understanding simulation solutions requires a post-processing tool to convert the data into something more meaningful. Ideally, the application would present an interactive visual representation of the numerical data for any dataset that was simulated while maintaining the accuracy of the calculated solution. Most CFD applications currently sacrifice interactivity for accuracy, yielding highly detailed flow descriptions hut limiting interaction for investigating the field.« less

A texture-based frameowrk for improving CFD data visualization in a virtual environment

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

Bivins, Gerrick O'Ron

2005-01-01

In the field of computational fluid dynamics (CFD) accurate representations of fluid phenomena can be simulated but require large amounts of data to represent the flow domain. Most datasets generated from a CFD simulation can be coarse, ~ 10,000 nodes or cells, or very fine with node counts on the order of 1,000,000. A typical dataset solution can also contain multiple solutions for each node, pertaining to various properties of the flow at a particular node. Scalar properties such as density, temperature, pressure, and velocity magnitude are properties that are typically calculated and stored in a dataset solution. Solutions aremore » not limited to just scalar properties. Vector quantities, such as velocity, are also often calculated and stored for a CFD simulation. Accessing all of this data efficiently during runtime is a key problem for visualization in an interactive application. Understanding simulation solutions requires a post-processing tool to convert the data into something more meaningful. Ideally, the application would present an interactive visual representation of the numerical data for any dataset that was simulated while maintaining the accuracy of the calculated solution. Most CFD applications currently sacrifice interactivity for accuracy, yielding highly detailed flow descriptions but limiting interaction for investigating the field.« less

Portraiture lens concept in a mobile phone camera

NASA Astrophysics Data System (ADS)

Sheil, Conor J.; Goncharov, Alexander V.

2017-11-01

A small form-factor lens was designed for the purpose of portraiture photography, the size of which allows use within smartphone casing. The current general requirement of mobile cameras having good all-round performance results in a typical, familiar, many-element design. Such designs have little room for improvement, in terms of the available degrees of freedom and highly-demanding target metrics such as low f-number and wide field of view. However, the specific application of the current portraiture lens relaxed the requirement of an all-round high-performing lens, allowing improvement of certain aspects at the expense of others. With a main emphasis on reducing depth of field (DoF), the current design takes advantage of the simple geometrical relationship between DoF and pupil diameter. The system has a large aperture, while a reasonable f-number gives a relatively large focal length, requiring a catadioptric lens design with double ray path; hence, field of view is reduced. Compared to typical mobile lenses, the large diameter reduces depth of field by a factor of four.

Phase sensitive thermography for quality assessment of giant magnetostrictive composite materials

NASA Astrophysics Data System (ADS)

Yang, Peng; Law, Chiu T.; Elhajjar, Rani

2017-04-01

Giant magnetostrictive materials are increasingly proposed for smart material applications such as in sensors, actuators, and energy harvesting applications. In a composites form, the materials are combined in particle form with polymer matrix composites. Reviewing the literature on this topic, the reader observes a large amount of variability in the reported properties that are typically based on recording (overall or localized) strain and magnetic field with non-collocating strain gages and a gauss meter, i.e. far field measurements. Previously the linking of the microstructure in magnetostrictive composite to the spatial variability of the localized magnetostrictive response, a significant factor for the composite performance in sensing and acutuation, has not been received adequate attention. In this paper, a full-field phase-sensitive thermography method is proposed to use full-field infrared measurements to infer changes in the microstructure in magnetostrictive polymer composites under a cyclic magnetic field. The results show how defects in the material can be rapidly identified from the proposed approach in inspecting the manufactured smart composites.

Diamond-Based Magnetic Imaging with Fourier Optical Processing

NASA Astrophysics Data System (ADS)

Backlund, Mikael P.; Kehayias, Pauli; Walsworth, Ronald L.

2017-11-01

Diamond-based magnetic field sensors have attracted great interest in recent years. In particular, wide-field magnetic imaging using nitrogen-vacancy (NV) centers in diamond has been previously demonstrated in condensed matter, biological, and paleomagnetic applications. Vector magnetic imaging with NV ensembles typically requires a significant applied field (>10 G ) to resolve the contributions from four crystallographic orientations, hindering studies of magnetic samples that require measurement in low or independently specified bias fields. Here we model and measure the complex amplitude distribution of NV emission at the microscope's Fourier plane and show that by modulating this collected light at the Fourier plane, one can decompose the NV ensemble magnetic resonance spectrum into its constituent orientations by purely optical means. This decomposition effectively extends the dynamic range at a given bias field and enables wide-field vector magnetic imaging at arbitrarily low bias fields, thus broadening potential applications of NV imaging and sensing. Our results demonstrate that NV-based microscopy stands to benefit greatly from Fourier optical approaches, which have already found widespread utility in other branches of microscopy.

AC electrothermal technique in microchannels

NASA Astrophysics Data System (ADS)

Salari, Alinaghi; Navi, Maryam; Dalton, Colin

2017-02-01

Electrokinetic techniques have a wide range of applications in droplet, particle, and fluid manipulation systems. In general, they can be categorized into different subgroups including electroosmosis, electrothermal, electrophoresis, dielectrophoresis, etc. The AC electrothermal (ACET) technique has been shown to be very effective in applications which involve high conductivity fluids, such as blood, which are typically used in biomedical applications. In the past few years, the ACET effect has received considerable attention. Unlike AC electroosmosis (ACEO), the ACET effect shows plateaus in force in a wide frequency range. In other words, with electrothermal force, velocity is more steady and predictable at different frequencies, compared to ACEO and dielectrophoresis (DEP). Although electrothermal microflows form as a result of Joule heating in the fluid, due to high conduction of heat to the ambience, the temperature rise in the fluid is not so high as to threaten the nature of the biofluids. The average temperature rise resulting from the ACET effect is below 5 °K. In order to generate high strength AC electric fields, microfabricated electrode arrays are commonly used in microchannels. For pumping applications, it is essential to create asymmetry in the electric field, typically by having asymmetrical electrode pairs. There is no defined border between many electrokinetic techniques, and as such the point where electrothermal processes interferes with other electrokinetic techniques is not clear in the literature. In addition, there have been comprehensive reviews on micropumps, electrokinetics, and their subcategories, but the literature lacks a detailed up-to-date review on electrothermal microdevices. In this paper, a brief review is made specifically on electric fields in ACET devices, in order to provide an insight for the reader about the importance of this aspect of ACET devices and the improvements made to date.

Comparison of contractile and extensile pneumatic artificial muscles

NASA Astrophysics Data System (ADS)

Pillsbury, Thomas E.; Wereley, Norman M.; Guan, Qinghua

2017-09-01

Pneumatic artificial muscles (PAMs) are used in robotic and prosthetic applications due to their high power to weight ratio, controllable compliance, and simple design. Contractile PAMs are typically used in traditional hard robotics in place of heavy electric motors. As the field of soft robotics grows, extensile PAMs are beginning to have increased usage. This work experimentally tests, models, and compares contractile and extensile PAMs to demonstrate the advantages and disadvantages of each type of PAM and applications for which they are best suited.

Development and laboratory testing of a 138-kV PPP-insulated joint for commercial application

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

Walldorf, S.P.; Chu, H.; Elbadaly, H.

1990-04-01

This paper describes the design, development and laboratory testing of a high voltage PPP (paper polypropylene/paper laminate) insulated joint for commercial application on 138-kV PPP-insulated cable. The design approach taken is conservative and addresses the typical variations in field conditions and in skill and workmanship of the splicing. Joint construction details, including choice of connector, taping structure, and joint mechanical reinforcement, are discussed. The test criteria are described and results are presented.

Bioinspired Intelligent Algorithm and Its Applications for Mobile Robot Control: A Survey.

PubMed

Ni, Jianjun; Wu, Liuying; Fan, Xinnan; Yang, Simon X

2016-01-01

Bioinspired intelligent algorithm (BIA) is a kind of intelligent computing method, which is with a more lifelike biological working mechanism than other types. BIAs have made significant progress in both understanding of the neuroscience and biological systems and applying to various fields. Mobile robot control is one of the main application fields of BIAs which has attracted more and more attention, because mobile robots can be used widely and general artificial intelligent algorithms meet a development bottleneck in this field, such as complex computing and the dependence on high-precision sensors. This paper presents a survey of recent research in BIAs, which focuses on the research in the realization of various BIAs based on different working mechanisms and the applications for mobile robot control, to help in understanding BIAs comprehensively and clearly. The survey has four primary parts: a classification of BIAs from the biomimetic mechanism, a summary of several typical BIAs from different levels, an overview of current applications of BIAs in mobile robot control, and a description of some possible future directions for research.

Bioinspired Intelligent Algorithm and Its Applications for Mobile Robot Control: A Survey

PubMed Central

Ni, Jianjun; Wu, Liuying; Fan, Xinnan; Yang, Simon X.

2016-01-01

Bioinspired intelligent algorithm (BIA) is a kind of intelligent computing method, which is with a more lifelike biological working mechanism than other types. BIAs have made significant progress in both understanding of the neuroscience and biological systems and applying to various fields. Mobile robot control is one of the main application fields of BIAs which has attracted more and more attention, because mobile robots can be used widely and general artificial intelligent algorithms meet a development bottleneck in this field, such as complex computing and the dependence on high-precision sensors. This paper presents a survey of recent research in BIAs, which focuses on the research in the realization of various BIAs based on different working mechanisms and the applications for mobile robot control, to help in understanding BIAs comprehensively and clearly. The survey has four primary parts: a classification of BIAs from the biomimetic mechanism, a summary of several typical BIAs from different levels, an overview of current applications of BIAs in mobile robot control, and a description of some possible future directions for research. PMID:26819582

Zero- to low-field MRI with averaging of concomitant gradient fields.

PubMed

Meriles, Carlos A; Sakellariou, Dimitris; Trabesinger, Andreas H; Demas, Vasiliki; Pines, Alexander

2005-02-08

Magnetic resonance imaging (MRI) encounters fundamental limits in circumstances in which the static magnetic field is not sufficiently strong to truncate unwanted, so-called concomitant components of the gradient field. This limitation affects the attainable optimal image fidelity and resolution most prominently in low-field imaging. In this article, we introduce the use of pulsed magnetic-field averaging toward relaxing these constraints. It is found that the image of an object can be retrieved by pulsed low fields in the presence of the full spatial variation of the imaging encoding gradient field even in the absence of the typical uniform high-field time-independent contribution. In addition, error-compensation schemes can be introduced through the application of symmetrized pulse sequences. Such schemes substantially mitigate artifacts related to evolution in strong magnetic-field gradients, magnetic fields that vary in direction and orientation, and imperfections of the applied field pulses.

Counting on Energy. Project E3 (Energy, Economics, and the Environment).

ERIC Educational Resources Information Center

Tully, Randolph R., Jr.; Reese, D. Chris

Five units are designed to provide an opportunity for in-depth, technical analysis in the fields of energy, economics, and the environment. In an effort to move upper elementary and secondary students beyond general awareness, activities call for the application of numbers where typically only vague generalities are discussed. Within each chapter,…

"Hey, I Can Do This!" The Benefits of Conducting Undergraduate Psychology Research for Young Adult Development

ERIC Educational Resources Information Center

Searight, H. Russell; Ratwik, Susan; Smith, Todd

2010-01-01

Many undergraduate programs require students to complete an independent research project in their major field prior to graduation. These projects are typically described as opportunities for integration of coursework and a direct application of the methods of inquiry specific to a particular discipline. Evaluations of curricular projects have…

Student-Teachers' Emotional Needs and Dichotomous Problem-Solving: Non-Cognitive Root Causes of Teaching and Learning Problems

ERIC Educational Resources Information Center

Soslau, Elizabeth

2016-01-01

This study investigated whether typical field instruction practice adequately addressed student-teachers' emotional needs and discerned whether unmet needs interrupted teacher learning. Four student-teachers completed weekly needs-based writing tasks, based on a broad application of Needs Theory. At the conclusion of the 16-week practicum, data…

Cross-Linked Hydrogel for Pharmaceutical Applications: A Review

PubMed Central

2017-01-01

Hydrogels are promising biomaterials because of their important qualities such as biocompatibility, biodegradability, hydrophilicity and non-toxicity. These qualities make hydrogels suitable for application in medical and pharmaceutical field. Recently, a tremendous growth of hydrogel application is seen, especially as gel and patch form, in transdermal drug delivery. This review mainly focuses on the types of hydrogels based on cross-linking and; secondly to describe the possible synthesis methods to design hydrogels for different pharmaceutical applications. The synthesis and chemistry of these hydrogels are discussed using specific pharmaceutical examples. The structure and water content in a typical hydrogel have also been discussed. PMID:29399542

Applications of the generalized information processing system (GIPSY)

USGS Publications Warehouse

Moody, D.W.; Kays, Olaf

1972-01-01

The Generalized Information Processing System (GIPSY) stores and retrieves variable-field, variable-length records consisting of numeric data, textual data, or codes. A particularly noteworthy feature of GIPSY is its ability to search records for words, word stems, prefixes, and suffixes as well as for numeric values. Moreover, retrieved records may be printed on pre-defined formats or formatted as fixed-field, fixed-length records for direct input to other-programs, which facilitates the exchange of data with other systems. At present there are some 22 applications of GIPSY falling in the general areas of bibliography, natural resources information, and management science, This report presents a description of each application including a sample input form, dictionary, and a typical formatted record. It is hoped that these examples will stimulate others to experiment with innovative uses of computer technology.

Out-of-field doses and neutron dose equivalents for electron beams from modern Varian and Elekta linear accelerators.

PubMed

Cardenas, Carlos E; Nitsch, Paige L; Kudchadker, Rajat J; Howell, Rebecca M; Kry, Stephen F

2016-07-08

Out-of-field doses from radiotherapy can cause harmful side effects or eventually lead to secondary cancers. Scattered doses outside the applicator field, neutron source strength values, and neutron dose equivalents have not been broadly investigated for high-energy electron beams. To better understand the extent of these exposures, we measured out-of-field dose characteristics of electron applicators for high-energy electron beams on two Varian 21iXs, a Varian TrueBeam, and an Elekta Versa HD operating at various energy levels. Out-of-field dose profiles and percent depth-dose curves were measured in a Wellhofer water phantom using a Farmer ion chamber. Neutron dose was assessed using a combination of moderator buckets and gold activation foils placed on the treatment couch at various locations in the patient plane on both the Varian 21iX and Elekta Versa HD linear accelerators. Our findings showed that out-of-field electron doses were highest for the highest electron energies. These doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. The Elekta linear accelerator had higher electron out-of-field doses than the Varian units examined, and the Elekta dose profiles exhibited a second dose peak about 20 to 30 cm from central-axis, which was found to be higher than typical out-of-field doses from photon beams. Electron doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. With respect to neutron dosimetry, Q values and neutron dose equivalents increased with electron beam energy. Neutron contamination from electron beams was found to be much lower than that from photon beams. Even though the neutron dose equivalent for electron beams represented a small portion of neutron doses observed under photon beams, neutron doses from electron beams may need to be considered for special cases.

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

French, Troy

Le Norman Energy Company conducted research on field application of alkaline-surfactant-polymer (ASP) flooding as a part of the U.S. Department of Energy's plan to maximize the production of our domestic oil resources. In addition to having substantial technical merit, the process uses chemicals that are environmentally acceptable. Le Norman's field project is located in the Sho-Vel-Tum (OK) oil field, which was a major producer of crude oil in past years, but has since been extensively waterflooded. This reservoir in this portion of the field is typical of many shallow reservoirs in the Oklahoma-Kansas area and is a good demonstration sitemore » for that area. The pay zones are located approximately 700 ft. deep, and this project is the shallowest field test for ASP flooding.« less

[Medical application of nano-materials].

PubMed

Jiang, Hui-qing; Chen, Yi-fei

2002-11-01

To review the research progress and medical application of nano-materials. The literature review and comprehensive analysis, methods were used in this study. The Nanotechnology is a typical crossing knowledge. It could be extensively applied in the fields of novel biomaterials, effective transmission of bioactive factor; the detection of functions for all vital organ systems, vascular circulation condition, the control of repair of burn trauma wounds will be monitored by the varied methods of nano technology combined with molecular biological engineering. The application of Nanotechnology will play important roles in clinical medicine, wound repair and basic research for the traditional Chinese medicine.

Design and evaluation of an imaging spectrophotometer incorporating a uniform light source.

PubMed

Noble, S D; Brown, R B; Crowe, T G

2012-03-01

Accounting for light that is diffusely scattered from a surface is one of the practical challenges in reflectance measurement. Integrating spheres are commonly used for this purpose in point measurements of reflectance and transmittance. This solution is not directly applicable to a spectral imaging application for which diffuse reflectance measurements are desired. In this paper, an imaging spectrophotometer design is presented that employs a uniform light source to provide diffuse illumination. This creates the inverse measurement geometry to the directional illumination/diffuse reflectance mode typically used for point measurements. The final system had a spectral range between 400 and 1000 nm with a 5.2 nm resolution, a field of view of approximately 0.5 m by 0.5 m, and millimeter spatial resolution. Testing results indicate illumination uniformity typically exceeding 95% and reflectance precision better than 1.7%.

Scalable wide-field optical coherence tomography-based angiography for in vivo imaging applications

PubMed Central

Xu, Jingjiang; Wei, Wei; Song, Shaozhen; Qi, Xiaoli; Wang, Ruikang K.

2016-01-01

Recent advances in optical coherence tomography (OCT)-based angiography have demonstrated a variety of biomedical applications in the diagnosis and therapeutic monitoring of diseases with vascular involvement. While promising, its imaging field of view (FOV) is however still limited (typically less than 9 mm2), which somehow slows down its clinical acceptance. In this paper, we report a high-speed spectral-domain OCT operating at 1310 nm to enable wide FOV up to 750 mm2. Using optical microangiography (OMAG) algorithm, we are able to map vascular networks within living biological tissues. Thanks to 2,048 pixel-array line scan InGaAs camera operating at 147 kHz scan rate, the system delivers a ranging depth of ~7.5 mm and provides wide-field OCT-based angiography at a single data acquisition. We implement two imaging modes (i.e., wide-field mode and high-resolution mode) in the OCT system, which gives highly scalable FOV with flexible lateral resolution. We demonstrate scalable wide-field vascular imaging for multiple finger nail beds in human and whole brain in mice with skull left intact at a single 3D scan, promising new opportunities for wide-field OCT-based angiography for many clinical applications. PMID:27231630

Harmonic field in knotted space

NASA Astrophysics Data System (ADS)

Duan, Xiuqing; Yao, Zhenwei

2018-04-01

Knotted fields enrich a variety of physical phenomena, ranging from fluid flows, electromagnetic fields, to textures of ordered media. Maxwell's electrostatic equations, whose vacuum solution is mathematically known as a harmonic field, provide an ideal setting to explore the role of domain topology in determining physical fields in confined space. In this work, we show the uniqueness of a harmonic field in knotted tubes, and reduce the construction of a harmonic field to a Neumann boundary value problem. By analyzing the harmonic field in typical knotted tubes, we identify the torsion driven transition from bipolar to vortex patterns. We also analogously extend our discussion to the organization of liquid crystal textures in knotted tubes. These results further our understanding about the general role of topology in shaping a physical field in confined space, and may find applications in the control of physical fields by manipulation of surface topology.

Quasi-Conformal Remapping For Compensation Of Human Visual Field Defects: Advances In Image Remapping For Human Field Defects

NASA Astrophysics Data System (ADS)

Juday, Richard D.; Loshin, David S.

1989-06-01

We are investigating image coordinate transformations possibly to be used in a low vision aid for human patients. These patients typically have field defects with localized retinal dysfunction predominately central (age related maculopathy) or peripheral (retinitis pigmentosa). Previously we have shown simple eccentricity-only remappings which do not maintain conformality. In this report we present our initial attempts on developing images which hold quasi-conformality after remapping. Although the quasi-conformal images may have less local distortion, there are discontinuities in the image which may counterindicate this type of transformation for the low vision application.

Studies of the Stability and Dynamics of Levitated Drops

NASA Technical Reports Server (NTRS)

Anikumar, A.; Lee, Chun Ping; Wang, T. G.

1996-01-01

This is a review of our experimental and theoretical studies relating to equilibrium and stability of liquid drops, typically of low viscosity, levitated in air by a sound field. The major emphasis here is on the physical principles and understanding behind the stability of levitated drops. A comparison with experimental data is also given, along with some fascinating pictures from high-speed photography. One of the aspects we shall deal with is how a drop can suddenly burst in an intense sound field; a phenomenon which can find applications in atomization technology. Also, we are currently investigating the phenomenon of suppression of coalescence between drops levitated in intense acoustic fields.

Note: Quasi-real-time analysis of dynamic near field scattering data using a graphics processing unit

NASA Astrophysics Data System (ADS)

Cerchiari, G.; Croccolo, F.; Cardinaux, F.; Scheffold, F.

2012-10-01

We present an implementation of the analysis of dynamic near field scattering (NFS) data using a graphics processing unit. We introduce an optimized data management scheme thereby limiting the number of operations required. Overall, we reduce the processing time from hours to minutes, for typical experimental conditions. Previously the limiting step in such experiments, the processing time is now comparable to the data acquisition time. Our approach is applicable to various dynamic NFS methods, including shadowgraph, Schlieren and differential dynamic microscopy.

High-frequency electric field measurement using a toroidal antenna

DOEpatents

Lee, Ki Ha

2002-01-01

A simple and compact method and apparatus for detecting high frequency electric fields, particularly in the frequency range of 1 MHz to 100 MHz, uses a compact toroidal antenna. For typical geophysical applications the sensor will be used to detect electric fields for a wide range of spectrum starting from about 1 MHz, in particular in the frequency range between 1 to 100 MHz, to detect small objects in the upper few meters of the ground. Time-varying magnetic fields associated with time-varying electric fields induce an emf (voltage) in a toroidal coil. The electric field at the center of (and perpendicular to the plane of) the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroidal coil one can easily and accurately determine the electric field.

Nonlinear relativistic plasma resonance: Renormalization group approach

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

Metelskii, I. I., E-mail: metelski@lebedev.ru; Kovalev, V. F., E-mail: vfkvvfkv@gmail.com; Bychenkov, V. Yu., E-mail: bychenk@lebedev.ru

An analytical solution to the nonlinear set of equations describing the electron dynamics and electric field structure in the vicinity of the critical density in a nonuniform plasma is constructed using the renormalization group approach with allowance for relativistic effects of electron motion. It is demonstrated that the obtained solution describes two regimes of plasma oscillations in the vicinity of the plasma resonance— stationary and nonstationary. For the stationary regime, the spatiotemporal and spectral characteristics of the resonantly enhanced electric field are investigated in detail and the effect of the relativistic nonlinearity on the spatial localization of the energy ofmore » the plasma relativistic field is considered. The applicability limits of the obtained solution, which are determined by the conditions of plasma wave breaking in the vicinity of the resonance, are established and analyzed in detail for typical laser and plasma parameters. The applicability limits of the earlier developed nonrelativistic theories are refined.« less

Spatial feature tracking impedence sensor using multiple electric fields

DOEpatents

Novak, J.L.

1998-08-11

Linear and other features on a workpiece are tracked by measuring the fields generated between electrodes arrayed in pairs. One electrode in each pair operates as a transmitter and the other as a receiver, and both electrodes in a pair are arrayed on a carrier. By combining and subtracting fields between electrodes in one pair and between a transmitting electrode in one pair and a receiving electrode in another pair, information describing the location and orientation of the sensor relative to the workpiece in up to six degrees of freedom may be obtained. Typical applications will measure capacitance, but other impedance components may be measured as well. The sensor is designed to track a linear feature axis or a protrusion or pocket in a workpiece. Seams and ridges can be tracked by this non-contact sensor. The sensor output is useful for robotic applications. 10 figs.

Spatial feature tracking impedence sensor using multiple electric fields

DOEpatents

Novak, James L.

1998-01-01

Linear and other features on a workpiece are tracked by measuring the fields generated between electrodes arrayed in pairs. One electrode in each pair operates as a transmitter and the other as a receiver, and both electrodes in a pair are arrayed on a carrier. By combining and subtracting fields between electrodes in one pair and between a transmitting electrode in one pair and a receiving electrode in another pair, information describing the location and orientation of the sensor relative to the workpiece in up to six degrees of freedom may be obtained. Typical applications will measure capacitance, but other impedance components may be measured as well. The sensor is designed to track a linear feature axis or a protrusion or pocket in a workpiece. Seams and ridges can be tracked by this non-contact sensor. The sensor output is useful for robotic applications.

Prediction of the Electromagnetic Field Distribution in a Typical Aircraft Using the Statistical Energy Analysis

NASA Astrophysics Data System (ADS)

Kovalevsky, Louis; Langley, Robin S.; Caro, Stephane

2016-05-01

Due to the high cost of experimental EMI measurements significant attention has been focused on numerical simulation. Classical methods such as Method of Moment or Finite Difference Time Domain are not well suited for this type of problem, as they require a fine discretisation of space and failed to take into account uncertainties. In this paper, the authors show that the Statistical Energy Analysis is well suited for this type of application. The SEA is a statistical approach employed to solve high frequency problems of electromagnetically reverberant cavities at a reduced computational cost. The key aspects of this approach are (i) to consider an ensemble of system that share the same gross parameter, and (ii) to avoid solving Maxwell's equations inside the cavity, using the power balance principle. The output is an estimate of the field magnitude distribution in each cavity. The method is applied on a typical aircraft structure.

Do terrorist attacks affect ethnic discrimination in the labour market? Evidence from two randomized field experiments.

PubMed

Birkelund, Gunn Elisabeth; Chan, Tak Wing; Ugreninov, Elisabeth; Midtbøen, Arnfinn H; Rogstad, Jon

2018-01-24

Terrorist attacks are known to influence public opinion. But do they also change behaviour? We address this question by comparing the results of two identical randomized field experiments on ethnic discrimination in hiring that we conducted in Oslo. The first experiment was conducted before the 2011 terrorist attacks in Norway; the second experiment was conducted after the attacks. In both experiments, applicants with a typical Pakistani name were significantly less likely to get a job interview compared to those with a typical Norwegian name. But the ethnic gap in call-back rates were very similar in the two experiments. Thus, Pakistanis in Norway still experienced the same level of discrimination, despite claims that Norwegians have become more positive about migrants after the far-right, anti-migrant terrorist attacks of 2011. © London School of Economics and Political Science 2018.

A DERATING METHOD FOR THERAPEUTIC APPLICATIONS OF HIGH INTENSITY FOCUSED ULTRASOUND

PubMed Central

Bessonova, O.V.; Khokhlova, V.A.; Canney, M.S.; Bailey, M.R.; Crum, L.A.

2010-01-01

Current methods of determining high intensity focused ultrasound (HIFU) fields in tissue rely on extrapolation of measurements in water assuming linear wave propagation both in water and in tissue. Neglecting nonlinear propagation effects in the derating process can result in significant errors. In this work, a new method based on scaling the source amplitude is introduced to estimate focal parameters of nonlinear HIFU fields in tissue. Focal values of acoustic field parameters in absorptive tissue are obtained from a numerical solution to a KZK-type equation and are compared to those simulated for propagation in water. Focal waveforms, peak pressures, and intensities are calculated over a wide range of source outputs and linear focusing gains. Our modeling indicates, that for the high gain sources which are typically used in therapeutic medical applications, the focal field parameters derated with our method agree well with numerical simulation in tissue. The feasibility of the derating method is demonstrated experimentally in excised bovine liver tissue. PMID:20582159

A derating method for therapeutic applications of high intensity focused ultrasound

NASA Astrophysics Data System (ADS)

Bessonova, O. V.; Khokhlova, V. A.; Canney, M. S.; Bailey, M. R.; Crum, L. A.

2010-05-01

Current methods of determining high intensity focused ultrasound (HIFU) fields in tissue rely on extrapolation of measurements in water assuming linear wave propagation both in water and in tissue. Neglecting nonlinear propagation effects in the derating process can result in significant errors. A new method based on scaling the source amplitude is introduced to estimate focal parameters of nonlinear HIFU fields in tissue. Focal values of acoustic field parameters in absorptive tissue are obtained from a numerical solution to a KZK-type equation and are compared to those simulated for propagation in water. Focal wave-forms, peak pressures, and intensities are calculated over a wide range of source outputs and linear focusing gains. Our modeling indicates, that for the high gain sources which are typically used in therapeutic medical applications, the focal field parameters derated with our method agree well with numerical simulation in tissue. The feasibility of the derating method is demonstrated experimentally in excised bovine liver tissue.

A DERATING METHOD FOR THERAPEUTIC APPLICATIONS OF HIGH INTENSITY FOCUSED ULTRASOUND.

PubMed

Bessonova, O V; Khokhlova, V A; Canney, M S; Bailey, M R; Crum, L A

2010-01-01

Current methods of determining high intensity focused ultrasound (HIFU) fields in tissue rely on extrapolation of measurements in water assuming linear wave propagation both in water and in tissue. Neglecting nonlinear propagation effects in the derating process can result in significant errors. In this work, a new method based on scaling the source amplitude is introduced to estimate focal parameters of nonlinear HIFU fields in tissue. Focal values of acoustic field parameters in absorptive tissue are obtained from a numerical solution to a KZK-type equation and are compared to those simulated for propagation in water. Focal waveforms, peak pressures, and intensities are calculated over a wide range of source outputs and linear focusing gains. Our modeling indicates, that for the high gain sources which are typically used in therapeutic medical applications, the focal field parameters derated with our method agree well with numerical simulation in tissue. The feasibility of the derating method is demonstrated experimentally in excised bovine liver tissue.

Using Software Testing Techniques for Efficient Handling of Programming Exercises in an e-Learning Platform

ERIC Educational Resources Information Center

Schwieren, Joachim; Vossen, Gottfried; Westerkamp, Peter

2006-01-01

e-Learning has become a major field of interest in recent years, and multiple approaches and solutions have been developed. A typical form of e-learning application comprises exercise submission and assessment systems that allow students to work on assignments whenever and where they want (i.e., dislocated, asynchronous work). In basic computer…

B. F. Skinner's contributions to applied behavior analysis

PubMed Central

Morris, Edward K.; Smith, Nathaniel G.; Altus, Deborah E.

2005-01-01

Our paper reviews and analyzes B. F. Skinner's contributions to applied behavior analysis in order to assess his role as the field's originator and founder. We found, first, that his contributions fall into five categorizes: the style and content of his science, his interpretations of typical and atypical human behavior, the implications he drew from his science for application, his descriptions of possible applications, and his own applications to nonhuman and human behavior. Second, we found that he explicitly or implicitly addressed all seven dimensions of applied behavior analysis. These contributions and the dimensions notwithstanding, he neither incorporated the field's scientific (e.g., analytic) and social dimensions (e.g., applied) into any program of published research such that he was its originator, nor did he systematically integrate, advance, and promote the dimensions so to have been its founder. As the founder of behavior analysis, however, he was the father of applied behavior analysis. PMID:22478444

Application of two-component phase Doppler interferometry to the measurement of particle size, mass flux, and velocities in two-phase flows

NASA Technical Reports Server (NTRS)

Mcdonell, V. G.; Samuelsen, G. S.

1989-01-01

Two-component phase Doppler interferometry is described, along with its application for the spatially-resolved measurements of particle size, velocity, and mass flux as well as continuous phase velocity. This technique measures single particle events at a point in the flow; droplet size is deduced from the spatial phase shift of the Doppler signal. Particle size influence and discrimination of continuous and discrete phases are among issues covered. Applications are presented for four cases: an example of the discrimination of two sizes of glass beads in a jet flow; a demonstration of the discrimination of phases in a spray field; an assessment of atomizer symmetry with respect to fuel distribution; and a characterization of a droplet field in a reacting spray. It is noted that the above technique is especially powerful in delineating droplet interactions in the swirling, complex flows typical of realistic systems.

Extending Raman's reach: enabling applications via greater sensitivity and speed

NASA Astrophysics Data System (ADS)

Creasey, David; Sullivan, Mike; Paul, Chris; Rathmell, Cicely

2018-02-01

Over the last decade, miniature fiber optic spectrometers have greatly expanded the ability of Raman spectroscopy to tackle practical applications in the field, from mobile pharmaceutical ID to hazardous material assessment in remote locations. There remains a gap, however, between the typical diode array spectrometer and their more sensitive benchtop analogs. High sensitivity, cooled Raman spectrometers have the potential to narrow that gap by providing greater sensitivity, better SNR, and faster measurement times. In this paper, we'll look at the key factors in the design of high sensitivity miniature Raman spectrometers and their associated accessories, as well as the key metric for direct comparison of these systems - limit of detection. With the availability of our high sensitivity Raman systems operating at wavelengths from the UV to NIR, many applications are now becoming practical in the field, from trace level detection to analysis of complex biological samples.

Combined Néel and Brown rotational Langevin dynamics in magnetic particle imaging, sensing, and therapy

NASA Astrophysics Data System (ADS)

Reeves, Daniel B.; Weaver, John B.

2015-11-01

Magnetic nanoparticles have been studied intensely because of their possible uses in biomedical applications. Biosensing using the rotational freedom of particles has been used to detect biomarkers for cancer, hyperthermia therapy has been used to treat tumors, and magnetic particle imaging is a promising new imaging modality that can spatially resolve the concentration of nanoparticles. There are two mechanisms by which the magnetization of a nanoparticle can rotate, a fact that poses a challenge for applications that rely on precisely one mechanism. The challenge is exacerbated by the high sensitivity of the dominant mechanism to applied fields. Here, we demonstrate stochastic Langevin equation simulations for the combined rotation in magnetic nanoparticles exposed to oscillating applied fields typical to these applications to both highlight the existing relevant theory and quantify which mechanism should occur in various parameter ranges.

Batch fabrication of precision miniature permanent magnets

DOEpatents

Christenson, Todd R.; Garino, Terry J.; Venturini, Eugene L.

2002-01-01

A new class of processes for fabrication of precision miniature rare earth permanent magnets is disclosed. Such magnets typically have sizes in the range 0.1 to 10 millimeters, and dimensional tolerances as small as one micron. Very large magnetic fields can be produced by such magnets, lending to their potential application in MEMS and related electromechanical applications, and in miniature millimeter-wave vacuum tubes. This abstract contains simplifications, and is supplied only for purposes of searching, not to limit or alter the scope or meaning of any claims herein.

An Application of Gröbner Basis in Differential Equations of Physics

NASA Astrophysics Data System (ADS)

Chaharbashloo, Mohammad Saleh; Basiri, Abdolali; Rahmany, Sajjad; Zarrinkamar, Saber

2013-11-01

We apply the Gröbner basis to the ansatz method in quantum mechanics to obtain the energy eigenvalues and the wave functions in a very simple manner. There are important physical potentials such as the Cornell interaction which play significant roles in particle physics and can be treated via this technique. As a typical example, the algorithm is applied to the semi-relativistic spinless Salpeter equation under the Cornell interaction. Many other applications of the idea in a wide range of physical fields are listed as well.

Virtual reality: past, present and future.

PubMed

Gobbetti, E; Scateni, R

1998-01-01

This report provides a short survey of the field of virtual reality, highlighting application domains, technological requirements, and currently available solutions. The report is organized as follows: section 1 presents the background and motivation of virtual environment research and identifies typical application domain, section 2 discusses the characteristics a virtual reality system must have in order to exploit the perceptual and spatial skills of users, section 3 surveys current input/output devices for virtual reality, section 4 surveys current software approaches to support the creation of virtual reality systems, and section 5 summarizes the report.

Building America Case Study: Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test, Minneapolis, Minnesota

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

T. Schirber, B. Schoenbauer

High-performance water heaters are typically more time consuming and costly to install in retrofit applications, making high-performance water heaters difficult to justify economically. However, recent advancements in high-performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high-efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands.

Transonic applications of the Wake Imaging System

NASA Astrophysics Data System (ADS)

Crowder, J. P.

1982-09-01

The extension of a rapid flow field survey method (wake imaging system) originally developed for low speed wind tunnel operation, to transonic wind tunnel applications is discussed. The advantage of the system, beside the simplicity and low cost of the data acquisition system, is that the probe position data are recorded as an optical image of the actual sensor and thus are unaffected by the inevitable deflections of the probe support. This permits traversing systems which are deliberately flexible and have unusual motions. Two transverse drive systems are described and several typical data images are given.

Smartphone application for multi-phasic interventional trials in psychiatry: Technical design of a smart server.

PubMed

Zhang, Melvyn W B; Ho, Roger C M

2017-01-01

Smartphones and their accompanying applications are currently widely utilized in various healthcare interventions. Prior to the deployment of these tools for healthcare intervention, typically, proof of concept feasibility studies, as well as randomized trials are conducted to determine that these tools are efficacious prior to their actual implementation. In the field of psychiatry, most of the current interventions seek to compare smartphone based intervention against conventional care. There remains a paucity of research evaluating different forms of interventions using a single smartphone application. In the field of nutrition, there has been recent pioneering research demonstrating how a multi-phasic randomized controlled trial could be conducted using a single smartphone application. Despite the innovativeness of the previous smartphone conceptualization, there remains a paucity of technical information underlying the conceptualization that would support a multi-phasic interventional trial. It is thus the aim of the current technical note to share insights into an innovative server design that would enable the delivery of multi-phasic trials.

Shape Biased Low Power Spin Dependent Tunneling Magnetic Field Sensors

NASA Astrophysics Data System (ADS)

Tondra, Mark; Qian, Zhenghong; Wang, Dexin; Nordman, Cathy; Anderson, John

2001-10-01

Spin Dependent Tunneling (SDT) devices are leading candidates for inclusion in a number of Unattended Ground Sensor applications. Continued progress at NVE has pushed their performance to 1OOs of pT I rt. Hz 1 Hz. However, these sensors were designed to use an applied field from an on-chip coil to create an appropriate magnetic sensing configuration. The power required to generate this field (^100mW) is significantly greater than the power budget (^lmW) for a magnetic sensor in an Unattended Ground Sensor (UGS) application. Consequently, a new approach to creating an ideal sensing environment is required. One approach being used at NVE is "shape biasing." This means that the physical layout of the SDT sensing elements is such that the magnetization of the sensing film is correct even when no biasing field is applied. Sensors have been fabricated using this technique and show reasonable promise for UGS applications. Some performance trade-offs exist. The power is easily tinder 1 MW, but the sensitivity is typically lower by a factor of 10. This talk will discuss some of the design details of these sensors as well as their expected ultimate performance.

Super-Alfvénic translation of a field-reversed configuration into a large-bore dielectric chamber

NASA Astrophysics Data System (ADS)

Sekiguchi, J.; Asai, T.; Takahashi, T.

2018-01-01

An experimental device to demonstrate additional heating and control methods for a field-reversed configuration (FRC) has been developed. The newly developed device, named FRC Amplification via Translation (FAT), has a field-reversed theta-pinch plasma source and a low-elongation dielectric (transparent quartz) confinement chamber with quasi-static confinement field. In the initial experiments on the FAT device, FRC translation and trapping were successfully demonstrated. Although the typical elongation of the trapped FRC in the confinement region was roughly three, no disruptive global instability, such as tilt, was observed. The FAT device increases the latitude to perform translation-related experiments, such as those concerning inductive current drive, equivalent neutral beam injection effects, and wave applications.

Lipid Nanotechnology

PubMed Central

Mashaghi, Samaneh; Jadidi, Tayebeh; Koenderink, Gijsje; Mashaghi, Alireza

2013-01-01

Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices and machines derived from engineering, physics, materials science, chemistry and biology. These devices have found applications in biomedical sciences, such as targeted drug delivery, bio-imaging, sensing and diagnosis of pathologies at early stages. In these applications, nano-devices typically interface with the plasma membrane of cells. On the other hand, naturally occurring nanostructures in biology have been a source of inspiration for new nanotechnological designs and hybrid nanostructures made of biological and non-biological, organic and inorganic building blocks. Lipids, with their amphiphilicity, diversity of head and tail chemistry, and antifouling properties that block nonspecific binding to lipid-coated surfaces, provide a powerful toolbox for nanotechnology. This review discusses the progress in the emerging field of lipid nanotechnology. PMID:23429269

Develop a Low Cost, Safe and Environmentally Benign High Energy and High Rate Reserve Battery

DTIC Science & Technology

2004-09-30

Methylimidazolium hexafluorophosphate BMItrif 1-Butyl-3-Methylimidazolium trifluoromethanesulfonate EC Ethylene carbonate EMC Ethyl methyl carbonate DEC...ionic liquid, a new field in lithium -based batteries, merits special recognition. The contribution of Dr. Mark Salomon with respect to the...applications. In particular, the anode is typically metallic lithium , and the cathode depolarizer is, most commonly, thionyl chloride (SOCl2) or sulfuryl

Mapping attractor fields in face space: the atypicality bias in face recognition.

PubMed

Tanaka, J; Giles, M; Kremen, S; Simon, V

1998-09-01

A familiar face can be recognized across many changes in the stimulus input. In this research, the many-to-one mapping of face stimuli to a single face memory is referred to as a face memory's 'attractor field'. According to the attractor field approach, a face memory will be activated by any stimuli falling within the boundaries of its attractor field. It was predicted that by virtue of its location in a multi-dimensional face space, the attractor field of an atypical face will be larger than the attractor field of a typical face. To test this prediction, subjects make likeness judgments to morphed faces that contained a 50/50 contribution from an atypical and a typical parent face. The main result of four experiments was that the morph face was judged to bear a stronger resemblance to the atypical face parent than the typical face parent. The computational basis of the atypicality bias was demonstrated in a neural network simulation where morph inputs of atypical and typical representations elicited stronger activation of atypical output units than of typical output units. Together, the behavioral and simulation evidence supports the view that the attractor fields of atypical faces span over a broader region of face space that the attractor fields of typical faces.

SEALDH-II-An Autonomous, Holistically Controlled, First Principles TDLAS Hygrometer for Field and Airborne Applications: Design-Setup-Accuracy/Stability Stress Test.

PubMed

Buchholz, Bernhard; Kallweit, Sören; Ebert, Volker

2016-12-30

Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside these commercial standard application specifications. Scientific instrumentation, however, is employing cutting-edge technology and often highly optimized but also lacks long-term field tests to assess the field vs. laboratory performance. Recently, we developed the Selective Extractive Laser Diode Hygrometer (SEALDH-II), which addresses field and especially airborne applications as well as metrological laboratory validations. SEALDH-II targets reducing deviations between airborne hygrometers (currently up to 20% between the most advanced hygrometers) with a new holistic, internal control and validation concept, which guarantees the transfer of the laboratory performance into a field scenario by capturing more than 80 instrument internal "housekeeping" data to nearly perfectly control SEALDH-II's health status. SEALDH-II uses a calibration-free, first principles based, direct Tuneable Diode Laser Absorption Spectroscopy (dTDLAS) approach, to cover the entire atmospheric humidity measurement range from about 3 to 40,000 ppmv with a calculated maximum uncertainty of 4.3% ± 3 ppmv. This is achieved not only by innovations in internal instrument monitoring and design, but also by active control algorithms such as a high resolution spectral stabilization. This paper describes the setup, working principles, and instrument stabilization, as well as its precision validation and long-term stress tests in an environmental chamber over an environmental temperature and humidity range of ΔT = 50 K and ΔRH = 80% RH, respectively.

SEALDH-II—An Autonomous, Holistically Controlled, First Principles TDLAS Hygrometer for Field and Airborne Applications: Design–Setup–Accuracy/Stability Stress Test

PubMed Central

Buchholz, Bernhard; Kallweit, Sören; Ebert, Volker

2016-01-01

Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside these commercial standard application specifications. Scientific instrumentation, however, is employing cutting-edge technology and often highly optimized but also lacks long-term field tests to assess the field vs. laboratory performance. Recently, we developed the Selective Extractive Laser Diode Hygrometer (SEALDH-II), which addresses field and especially airborne applications as well as metrological laboratory validations. SEALDH-II targets reducing deviations between airborne hygrometers (currently up to 20% between the most advanced hygrometers) with a new holistic, internal control and validation concept, which guarantees the transfer of the laboratory performance into a field scenario by capturing more than 80 instrument internal “housekeeping” data to nearly perfectly control SEALDH-II’s health status. SEALDH-II uses a calibration-free, first principles based, direct Tuneable Diode Laser Absorption Spectroscopy (dTDLAS) approach, to cover the entire atmospheric humidity measurement range from about 3 to 40,000 ppmv with a calculated maximum uncertainty of 4.3% ± 3 ppmv. This is achieved not only by innovations in internal instrument monitoring and design, but also by active control algorithms such as a high resolution spectral stabilization. This paper describes the setup, working principles, and instrument stabilization, as well as its precision validation and long-term stress tests in an environmental chamber over an environmental temperature and humidity range of ΔT = 50 K and ΔRH = 80% RH, respectively. PMID:28042844

NASA-JPL overview, space technology and relevance to medicine (Conference Presentation)

NASA Astrophysics Data System (ADS)

van Zyl, Jakob

2017-05-01

There is special synergy between NASA space instruments and medical devices, especially those that may be implanted in the human body. For example, in both cases instruments have to be small, typically have to consume little power and often have to operate in harsh environments. JPL has a long history in using this synergy to leverage from the technology developed for space missions for application in medical fields. In this talk, we discuss the general overlap of technological requirements in the medical field and space science. We will highlight some examples where JPL instrumentation and engineering has been transferred successfully.

Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field. [plasma centrifuge for isotope separation

NASA Technical Reports Server (NTRS)

Hong, S. H.; Wilhelm, H. E.

1978-01-01

An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.

Optical fiber designs for beam shaping

NASA Astrophysics Data System (ADS)

Farley, Kevin; Conroy, Michael; Wang, Chih-Hao; Abramczyk, Jaroslaw; Campbell, Stuart; Oulundsen, George; Tankala, Kanishka

2014-03-01

A large number of power delivery applications for optical fibers require beams with very specific output intensity profiles; in particular applications that require a focused high intensity beam typically image the near field (NF) intensity distribution at the exit surface of an optical fiber. In this work we discuss optical fiber designs that shape the output beam profile to more closely correspond to what is required in many real world industrial applications. Specifically we present results demonstrating the ability to transform Gaussian beams to shapes required for industrial applications and how that relates to system parameters such as beam product parameter (BPP) values. We report on the how different waveguide structures perform in the NF and show results on how to achieve flat-top with circular outputs.

Tailoring Functional Chitosan-based Composites for Food Applications.

PubMed

Nunes, Cláudia; Coimbra, Manuel A; Ferreira, Paula

2018-03-08

Chitosan-based functional materials are emerging for food applications. The covalent bonding of molecular entities demonstrates to enhance resistance to the typical acidity of food assigning mechanical and moisture/gas barrier properties. Moreover, the grafting to chitosan of some functional molecules, like phenolic compounds or essential oils, gives antioxidant, antimicrobial, among others properties to chitosan. The addition of nanofillers to chitosan and other biopolymers improves the already mentioned required properties for food applications and can attribute electrical conductivity and magnetic properties for active and intelligent packaging. Electrical conductivity is a required property for the processing of food at low temperature using electric fields or for sensors application. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A programmable display layer for virtual reality system architectures.

PubMed

Smit, Ferdi Alexander; van Liere, Robert; Froehlich, Bernd

2010-01-01

Display systems typically operate at a minimum rate of 60 Hz. However, existing VR-architectures generally produce application updates at a lower rate. Consequently, the display is not updated by the application every display frame. This causes a number of undesirable perceptual artifacts. We describe an architecture that provides a programmable display layer (PDL) in order to generate updated display frames. This replaces the default display behavior of repeating application frames until an update is available. We will show three benefits of the architecture typical to VR. First, smooth motion is provided by generating intermediate display frames by per-pixel depth-image warping using 3D motion fields. Smooth motion eliminates various perceptual artifacts due to judder. Second, we implement fine-grained latency reduction at the display frame level using a synchronized prediction of simulation objects and the viewpoint. This improves the average quality and consistency of latency reduction. Third, a crosstalk reduction algorithm for consecutive display frames is implemented, which improves the quality of stereoscopic images. To evaluate the architecture, we compare image quality and latency to that of a classic level-of-detail approach.

Vortex dynamics and irreversibility line in optimally doped SmFeAsO0.8F0.2 from ac susceptibility and magnetization measurements

NASA Astrophysics Data System (ADS)

Prando, G.; Carretta, P.; de Renzi, R.; Sanna, S.; Palenzona, A.; Putti, M.; Tropeano, M.

2011-05-01

Ac susceptibility and static magnetization measurements were performed in the optimally doped SmFeAsO0.8F0.2 superconductor. The field-temperature phase diagram of the superconducting state was drawn, and, in particular, the features of the flux lines were derived. The dependence of the intragrain depinning energy on the magnetic field intensity was derived in the thermally activated flux-creep framework, enlightening a typical 1/H dependence in the high-field regime. The intragrain critical current density was extrapolated in the zero-temperature and zero-magnetic-field limit, showing a remarkably high value Jc0(0)~2×107 A/cm2, which demonstrates that this material is rather interesting for potential future technological applications.

Horizontal wells up odds for profit in Giddings Austin chalk

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

Maloy, W.T.

1992-02-17

This paper reports on horizontal drilling in the Giddings field Austin chalk which has significantly improved average well recoveries and more than offset increased drilling costs. Although not the panacea originally promoted, horizontal drilling, in Giddings field, offers economic profits to the average investor. Economic analysis indicates that the typical investor is making money by earning returns in excess of market values. Field-wide development will, therefore, remain active unless oil prices or average well recoveries fall below $12/bbl or 112,000 bbl of oil equivalent (BOE), respectively. The application of technological innovation in the Giddings field may culminate in the drillingmore » of over 2,000 horizontal Austin chalk wells, and has conceivably increased recoverable reserves by 400 million BOE.« less

Station-Keeping Requirements for Astronomical Imaging with Constellations of Free-Flying Collectors

NASA Technical Reports Server (NTRS)

Allen, Ronald J.

2004-01-01

The requirements on station-keeping for constellations of free-flying collectors coupled as (future) imaging arrays in space for astrophysics applications are discussed. The typical knowledge precision required in the plane of the array depends on the angular size of the targets of interest; it is generally at a level of tens of centimeters for typical stellar targets, becoming of order centimeters only for the widest attainable fields of view. In the "piston" direction, perpendicular to the array, the typical knowledge precision required depends on the bandwidth of the signal, and is at a level of tens of wavelengths for narrow approx. 1% signal bands, becoming of order one wavelength only for the broadest bandwidths expected to be useful. The significance of this result is that, at this level of precision, it may be possible to provide the necessary knowledge of array geometry without the use of signal photons, thereby allowing observations of faint targets. "Closure-phase" imaging is a technique which has been very successfully applied to surmount instabilities owing to equipment and to the atmosphere, and which appears to be directly applicable to space imaging arrays where station-keeping drifts play the same role as (slow) atmospheric and equipment instabilities.

Gel integration for microfluidic applications.

PubMed

Zhang, Xuanqi; Li, Lingjun; Luo, Chunxiong

2016-05-21

Molecular diffusive membranes or materials are important for biological applications in microfluidic systems. Hydrogels are typical materials that offer several advantages, such as free diffusion for small molecules, biocompatibility with most cells, temperature sensitivity, relatively low cost, and ease of production. With the development of microfluidic applications, hydrogels can be integrated into microfluidic systems by soft lithography, flow-solid processes or UV cure methods. Due to their special properties, hydrogels are widely used as fluid control modules, biochemical reaction modules or biological application modules in different applications. Although hydrogels have been used in microfluidic systems for more than ten years, many hydrogels' properties and integrated techniques have not been carefully elaborated. Here, we systematically review the physical properties of hydrogels, general methods for gel-microfluidics integration and applications of this field. Advanced topics and the outlook of hydrogel fabrication and applications are also discussed. We hope this review can help researchers choose suitable methods for their applications using hydrogels.

Training the 21st-Century Worker: Policy Advice from the Dark Network of Implicit Memory. IBE Working Papers on Curriculum Issues No. 16

ERIC Educational Resources Information Center

Abadzi, Helen

2015-01-01

Research on memory functions and their applications is a vast field that has unfolded for decades; some important studies are sixty years old. However, the research has remained a well-kept secret of cognitive psychologists. Education faculties rarely teach memory specifics, so people working in education typically do not know about the above…

Increasing the lego of 2D electronics materials: silicene and germanene, graphene's new synthetic cousins

NASA Astrophysics Data System (ADS)

Le Lay, Guy; Salomon, Eric; Angot, Thierry; Eugenia Dávila, Maria

2015-05-01

The realization of the first Field Effect Transistors operating at room temperature, based on a single layer silicene channel, open up highly promising perspectives, e.g., typically, for applications in digital electronics. Here, we describe recent results on the growth, characterization and electronic properties of novel synthetic two-dimensional materials beyond graphene, namely silicene and germanene, its silicon and germanium counterparts.

Generation of Particles and Seeding

NASA Technical Reports Server (NTRS)

Meyers, James F.

1991-01-01

One of the most important elements in laser velocimetry, yet the most neglected, is the small particle embedded in the flow field that scatters the light necessary to make velocity measurements. An attempt to remove the confusion in choosing a seeding method by assessing many of the techniques currently used is presented. Their characteristics and typical limitations imposed by various applications are outlined. The ramifications of these methods on measurement accuracy are addressed.

Coal-Burning Technologies Applicable to Air Force Central Heating Plants

DTIC Science & Technology

1989-12-01

8 3. DESCRIPTION OF REPLACEMENT OR EXPANSION TECHNOLOGIES ........ 9 3.1.1 Shell (Fire- Tube ) Boilers ........... 9...3.1.2 Water- Tube Boilers .*.*........***.... 10 3.1.3 Packaged vs Field-Erected Construction ...... 11 3.2 STOKER FIRING ...... .. 11 3.2.1 Description...FIGURES 4 Figure Pg 1 Schematic diagram of a typical scotch shell boiler: wet-back, three-pass design ..~............... 9 2 Commnon tube patterns for

From astronomy and telecommunications to biomedicine

NASA Astrophysics Data System (ADS)

Behr, Bradford B.; Baker, Scott A.; Bismilla, Yusuf; Cenko, Andrew T.; DesRoches, Brandon; Hajian, Arsen R.; Meade, Jeffrey T.; Nitkowski, Arthur; Preston, Kyle J.; Schmidt, Bradley S.; Sherwood-Droz, Nicolás.; Slaa, Jared

2015-03-01

Photonics is an inherently interdisciplinary endeavor, as technologies and techniques invented or developed in one scientific field are often found to be applicable to other fields or disciplines. We present two case studies in which optical spectroscopy technologies originating from stellar astrophysics and optical telecommunications multiplexing have been successfully adapted for biomedical applications. The first case involves a design concept called the High Throughput Virtual Slit, or HTVS, which provides high spectral resolution without the throughput inefficiency typically associated with a narrow spectrometer slit. HTVS-enhanced spectrometers have been found to significantly improve the sensitivity and speed of fiber-fed Raman analysis systems, and the method is now being adapted for hyperspectral imaging for medical and biological sensing. The second example of technology transfer into biomedicine centers on integrated optics, in which optical waveguides are fabricated on to silicon substrates in a substantially similar fashion as integrated circuits in computer chips. We describe an architecture referred to as OCTANE which implements a small and robust "spectrometer-on-a-chip" which is optimized for optical coherence tomography (OCT). OCTANE-based OCT systems deliver three-dimensional imaging resolution at the micron scale with greater stability and lower cost than equivalent conventional OCT approaches. Both HTVS and OCTANE enable higher precision and improved reliability under environmental conditions that are typically found in a clinical or laboratory setting.

Application of closed-form solutions to a mesh point field in silicon solar cells

NASA Technical Reports Server (NTRS)

Lamorte, M. F.

1985-01-01

A computer simulation method is discussed that provides for equivalent simulation accuracy, but that exhibits significantly lower CPU running time per bias point compared to other techniques. This new method is applied to a mesh point field as is customary in numerical integration (NI) techniques. The assumption of a linear approximation for the dependent variable, which is typically used in the finite difference and finite element NI methods, is not required. Instead, the set of device transport equations is applied to, and the closed-form solutions obtained for, each mesh point. The mesh point field is generated so that the coefficients in the set of transport equations exhibit small changes between adjacent mesh points. Application of this method to high-efficiency silicon solar cells is described; and the method by which Auger recombination, ambipolar considerations, built-in and induced electric fields, bandgap narrowing, carrier confinement, and carrier diffusivities are treated. Bandgap narrowing has been investigated using Fermi-Dirac statistics, and these results show that bandgap narrowing is more pronounced and that it is temperature-dependent in contrast to the results based on Boltzmann statistics.

Aggregation-Induced Emission of Multiphenyl-Substituted 1,3-Butadiene Derivatives: Synthesis, Property and Application.

PubMed

Zhang, Yahui; Mao, Huiling; Xu, Weiquan; Shi, Jianbing; Cai, Zhengxu; Tong, Bin; Dong, Yuping

2018-05-29

Organic functional materials, including conjugated molecules and fluorescent dyes, have been rapidly developed in recent years because they can be applied in many fields, such as solar cells, biosensing and bioimaging, and medical adjuvant therapy. Organic functional materials with aggregation-induced emission or aggregation-enhanced emission (AIE/AEE) characteristics have increasingly attracted attention due to their high quantum efficiency in the aggregated or solid state. A large variety of AIE/AEE materials have been designed and applied during the exponential growth of research interest in the abovementioned fields. Multiphenyl-substituted 1,3-butadiene (MPB), as a core structure that includes tetraphenyl-1,3-butadiene, hexaphenyl-1,3-butadiene and their derivatives, show a typical AIE/AEE feature and can be potentially used in all the abovementioned fields. This review summarizes the design principles, the corresponding syntheses, and the structure-property relationships of MPBs, as well as their excellent innovative functionalities and applications. This review will be very useful for scientists conducting chemistry, materials, and biomedical research in AIE/AEE-related fields. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design and application of permanent magnet flux sources for mechanical testing of magnetoactive elastomers at variable field directions.

PubMed

Hiptmair, F; Major, Z; Haßlacher, R; Hild, S

2015-08-01

Magnetoactive elastomers (MAEs) are a class of smart materials whose mechanical properties can be rapidly and reversibly changed by an external magnetic field. Due to this tunability, they are useable for actuators or in active vibration control applications. An extensive magnetomechanical characterization is necessary for MAE material development and requires experiments under cyclic loading in uniform but variable magnetic fields. MAE testing apparatus typically rely on fields of adjustable strength, but fixed (transverse) direction, often provided by electromagnets. In this work, two permanent magnet flux sources were developed as an add-on for a modular test stand, to allow for mechanical testing in uniform fields of variable direction. MAE specimens, based on a silicone matrix with isotropic and anisotropic carbonyl iron particle distributions, were subjected to dynamic mechanical analysis under different field and loading configurations. The magneto-induced increase of stiffness and energy dissipation was determined by the change of the hysteresis loop area and dynamic modulus values. A distinct influence of the composite microstructure and the loading state was observed. Due to the very soft and flexible matrix used for preparing the MAE samples, the material stiffness and damping behavior could be varied over a wide range via the applied field direction and intensity.

Dielectric elastomer actuators used for pneumatic valve technology

NASA Astrophysics Data System (ADS)

Giousouf, Metin; Kovacs, Gabor

2013-10-01

Dielectric elastomer actuators have been investigated for applications in the field of pneumatic automation technology. We have developed different valve designs with stacked dielectric elastomer actuators and with integrated high voltage converters. The actuators were made using VHB-4910 material and a stacker machine for automated fabrication of the cylindrical actuators. Typical characteristics of pneumatic valves such as flow rate, power consumption and dynamic behaviour are presented. For valve construction the force and stroke parameters of the dielectric elastomer actuator have been measured. Further, benefits for valve applications using dielectric elastomers are shown as well as their potential operational area. Finally, challenges are discussed that are relevant for the use of elastomer actuators in valves for industrial applications.

A Dual-Plane PIV Study of Turbulent Heat Transfer Flows

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

A perspective on high-frequency ultrasound for medical applications

NASA Astrophysics Data System (ADS)

Mamou, Jonathan; Aristizába, Orlando; Silverman, Ronald H.; Ketterling, Jeffrey A.

2010-01-01

High-frequency ultrasound (HFU, >15 MHz) is a rapidly developing field. HFU is currently used and investigated for ophthalmologic, dermatologic, intravascular, and small-animal imaging. HFU offers a non-invasive means to investigate tissue at the microscopic level with resolutions often better than 100 μm. However, fine resolution is only obtained over the limited depth-of-field (˜1 mm) of single-element spherically-focused transducers typically used for HFU applications. Another limitation is penetration depth because most biological tissues have large attenuation at high frequencies. In this study, two 5-element annular arrays with center frequencies of 17 and 34 MHz were fabricated and methods were developed to obtain images with increased penetration depth and depth-of-field. These methods were used in ophthalmologic and small-animal imaging studies. Improved blood sensitivity was obtained when a phantom mimicking a vitreous hemorrhage was imaged. Central-nervous systems of 12.5-day-old mouse embryos were imaged in utero and in three dimensions for the first time.

Iron Oxide Nanocrystals for Magnetic Hyperthermia Applications

PubMed Central

Armijo, Leisha M.; Brandt, Yekaterina I.; Mathew, Dimple; Yadav, Surabhi; Maestas, Salomon; Rivera, Antonio C.; Cook, Nathaniel C.; Withers, Nathan J.; Smolyakov, Gennady A.; Adolphi, Natalie; Monson, Todd C.; Huber, Dale L.; Smyth, Hugh D. C.; Osiński, Marek

2012-01-01

Magnetic nanocrystals have been investigated extensively in the past several years for several potential applications, such as information technology, MRI contrast agents, and for drug conjugation and delivery. A specific property of interest in biomedicine is magnetic hyperthermia—an increase in temperature resulting from the thermal energy released by magnetic nanocrystals in an external alternating magnetic field. Iron oxide nanocrystals of various sizes and morphologies were synthesized and tested for specific losses (heating power) using frequencies of 111.1 kHz and 629.2 kHz, and corresponding magnetic field strengths of 9 and 25 mT. Polymorphous nanocrystals as well as spherical nanocrystals and nanowires in paramagnetic to ferromagnetic size range exhibited good heating power. A remarkable 30 °C temperature increase was observed in a nanowire sample at 111 kHz and magnetic field of 25 mT (19.6 kA/m), which is very close to the typical values of 100 kHz and 20 mT used in medical treatments. PMID:28348300

Patterning technology for solution-processed organic crystal field-effect transistors

PubMed Central

Li, Yun; Sun, Huabin; Shi, Yi; Tsukagoshi, Kazuhito

2014-01-01

Organic field-effect transistors (OFETs) are fundamental building blocks for various state-of-the-art electronic devices. Solution-processed organic crystals are appreciable materials for these applications because they facilitate large-scale, low-cost fabrication of devices with high performance. Patterning organic crystal transistors into well-defined geometric features is necessary to develop these crystals into practical semiconductors. This review provides an update on recentdevelopment in patterning technology for solution-processed organic crystals and their applications in field-effect transistors. Typical demonstrations are discussed and examined. In particular, our latest research progress on the spin-coating technique from mixture solutions is presented as a promising method to efficiently produce large organic semiconducting crystals on various substrates for high-performance OFETs. This solution-based process also has other excellent advantages, such as phase separation for self-assembled interfaces via one-step spin-coating, self-flattening of rough interfaces, and in situ purification that eliminates the impurity influences. Furthermore, recommendations for future perspectives are presented, and key issues for further development are discussed. PMID:27877656

Practical use of video imagery in nearshore oceanographic field studies

USGS Publications Warehouse

Holland, K.T.; Holman, R.A.; Lippmann, T.C.; Stanley, J.; Plant, N.

1997-01-01

An approach was developed for using video imagery to quantify, in terms of both spatial and temporal dimensions, a number of naturally occurring (nearshore) physical processes. The complete method is presented, including the derivation of the geometrical relationships relating image and ground coordinates, principles to be considered when working with video imagery and the two-step strategy for calibration of the camera model. The techniques are founded on the principles of photogrammetry, account for difficulties inherent in the use of video signals, and have been adapted to allow for flexibility of use in field studies. Examples from field experiments indicate that this approach is both accurate and applicable under the conditions typically experienced when sampling in coastal regions. Several applications of the camera model are discussed, including the measurement of nearshore fluid processes, sand bar length scales, foreshore topography, and drifter motions. Although we have applied this method to the measurement of nearshore processes and morphologic features, these same techniques are transferable to studies in other geophysical settings.

Advanced Biasing Experiments on the C-2 Field-Reversed Configuration Device

NASA Astrophysics Data System (ADS)

Thompson, Matthew; Korepanov, Sergey; Garate, Eusebio; Yang, Xiaokang; Gota, Hiroshi; Douglass, Jon; Allfrey, Ian; Valentine, Travis; Uchizono, Nolan; TAE Team

2014-10-01

The C-2 experiment seeks to study the evolution, heating and sustainment effects of neutral beam injection on field-reversed configuration (FRC) plasmas. Recently, substantial improvements in plasma performance were achieved through the application of edge biasing with coaxial plasma guns located in the divertors. Edge biasing provides rotation control that reduces instabilities and E × B shear that improves confinement. Typically, the plasma gun arcs are run at ~ 10 MW for the entire shot duration (~ 5 ms), which will become unsustainable as the plasma duration increases. We have conducted several advanced biasing experiments with reduced-average-power plasma gun operating modes and alternative biasing cathodes in an effort to develop an effective biasing scenario applicable to steady state FRC plasmas. Early results show that several techniques can potentially provide effective, long-duration edge biasing.

Ultrasound Imaging Velocimetry: a review

NASA Astrophysics Data System (ADS)

Poelma, Christian

2017-01-01

Whole-field velocity measurement techniques based on ultrasound imaging (a.k.a. `ultrasound imaging velocimetry' or `echo-PIV') have received significant attention from the fluid mechanics community in the last decade, in particular because of their ability to obtain velocity fields in flows that elude characterisation by conventional optical methods. In this review, an overview is given of the history, typical components and challenges of these techniques. The basic principles of ultrasound image formation are summarised, as well as various techniques to estimate flow velocities; the emphasis is on correlation-based techniques. Examples are given for a wide range of applications, including in vivo cardiovascular flow measurements, the characterisation of sediment transport and the characterisation of complex non-Newtonian fluids. To conclude, future opportunities are identified. These encompass not just optimisation of the accuracy and dynamic range, but also extension to other application areas.

Discriminative Random Field Models for Subsurface Contamination Uncertainty Quantification

NASA Astrophysics Data System (ADS)

Arshadi, M.; Abriola, L. M.; Miller, E. L.; De Paolis Kaluza, C.

2017-12-01

Application of flow and transport simulators for prediction of the release, entrapment, and persistence of dense non-aqueous phase liquids (DNAPLs) and associated contaminant plumes is a computationally intensive process that requires specification of a large number of material properties and hydrologic/chemical parameters. Given its computational burden, this direct simulation approach is particularly ill-suited for quantifying both the expected performance and uncertainty associated with candidate remediation strategies under real field conditions. Prediction uncertainties primarily arise from limited information about contaminant mass distributions, as well as the spatial distribution of subsurface hydrologic properties. Application of direct simulation to quantify uncertainty would, thus, typically require simulating multiphase flow and transport for a large number of permeability and release scenarios to collect statistics associated with remedial effectiveness, a computationally prohibitive process. The primary objective of this work is to develop and demonstrate a methodology that employs measured field data to produce equi-probable stochastic representations of a subsurface source zone that capture the spatial distribution and uncertainty associated with key features that control remediation performance (i.e., permeability and contamination mass). Here we employ probabilistic models known as discriminative random fields (DRFs) to synthesize stochastic realizations of initial mass distributions consistent with known, and typically limited, site characterization data. Using a limited number of full scale simulations as training data, a statistical model is developed for predicting the distribution of contaminant mass (e.g., DNAPL saturation and aqueous concentration) across a heterogeneous domain. Monte-Carlo sampling methods are then employed, in conjunction with the trained statistical model, to generate realizations conditioned on measured borehole data. Performance of the statistical model is illustrated through comparisons of generated realizations with the `true' numerical simulations. Finally, we demonstrate how these realizations can be used to determine statistically optimal locations for further interrogation of the subsurface.

Near field magnetic communications for helmet-mounted display applications

NASA Astrophysics Data System (ADS)

Field, Mark; Sailer, Alan

2005-05-01

Helmet-mounted displays need a data feed that is typically provided by a cable or RF wireless data link to an external computer. In defense applications these solutions are problematic: a cable gets in the way and restricts use and emergency egress, while an RF wireless link can be detected at some distance giving away position and is susceptible to jamming. What is required is an alternative wireless technology that is low power, extremely localized and difficult to detect or jam. Near field magnetic communications is one possible alternative to RF communications that may fulfill these needs. This technology uses a time varying magnetic field to carry information, and is only useable over small distances of order six feet. This is expected to have significant advantages for particular applications: notably power requirements and security compared with RF wireless links. The power stored in a magnetic field falls off as 1/r6, compared with 1/r2 for RF, which means that all the power is localized around the transmitter. By having a physically small communications region around each platform or user, a large bandwidth can be guaranteed by allowing the reuse of the frequency spectrum outside the immediate vicinity. It also confers security on the data-link, as the signal is undetectable beyond the short range of the system.

Homochiral metal-organic frameworks and their application in chromatography enantioseparations.

PubMed

Peluso, Paola; Mamane, Victor; Cossu, Sergio

2014-10-10

The last frontier in the chiral stationary phases (CSPs) field for chromatography enantioseparations is represented by homochiral metal-organic frameworks (MOFs), a class of organic-inorganic hybrid materials built from metal-connecting nodes and organic-bridging ligands. The modular nature of these materials allows to design focused structures by combining properly metal, organic ligands and rigid polytopic spacers. Intriguingly, chiral ligands introduce molecular chirality in the MOF-network as well as homochirality in the secondary structure of materials (such as homohelicity) producing homochiral nets in a manner mimicking biopolymers (proteins, polysaccharides) which are characterized by a definite helical sense associated with the chirality of their building blocks (amino acids or sugars). Nowadays, robust and flexible materials characterized by high porosity and surface area became available by using preparative procedures typical of the so-called reticular synthesis. This review focuses on recent developments in the synthesis and applications of homochiral MOFs as supports for chromatography enantioseparations. Indeed, despite this field is in its infancy, interesting results have been produced and a critical overview of the 12 reported applications for gas chromatography (GC) and high-performance liquid chromatography (HPLC) can orient the reader approaching the field. Mechanistic aspects are shortly discussed and a view regarding future trends in this field is provided. Copyright © 2014 Elsevier B.V. All rights reserved.

Correction factors for ionization chamber measurements with the ‘Valencia’ and ‘large field Valencia’ brachytherapy applicators

NASA Astrophysics Data System (ADS)

Gimenez-Alventosa, V.; Gimenez, V.; Ballester, F.; Vijande, J.; Andreo, P.

2018-06-01

Treatment of small skin lesions using HDR brachytherapy applicators is a widely used technique. The shielded applicators currently available in clinical practice are based on a tungsten-alloy cup that collimates the source-emitted radiation into a small region, hence protecting nearby tissues. The goal of this manuscript is to evaluate the correction factors required for dose measurements with a plane-parallel ionization chamber typically used in clinical brachytherapy for the ‘Valencia’ and ‘large field Valencia’ shielded applicators. Monte Carlo simulations have been performed using the PENELOPE-2014 system to determine the absorbed dose deposited in a water phantom and in the chamber active volume with a Type A uncertainty of the order of 0.1%. The average energies of the photon spectra arriving at the surface of the water phantom differ by approximately 10%, being 384 keV for the ‘Valencia’ and 343 keV for the ‘large field Valencia’. The ionization chamber correction factors have been obtained for both applicators using three methods, their values depending on the applicator being considered. Using a depth-independent global chamber perturbation correction factor and no shift of the effective point of measurement yields depth-dose differences of up to 1% for the ‘Valencia’ applicator. Calculations using a depth-dependent global perturbation factor, or a shift of the effective point of measurement combined with a constant partial perturbation factor, result in differences of about 0.1% for both applicators. The results emphasize the relevance of carrying out detailed Monte Carlo studies for each shielded brachytherapy applicator and ionization chamber.

Contact flexible microstrip applicators (CFMA) in a range from microwaves up to short waves.

PubMed

Gelvich, Edward A; Mazokhin, Vladimir N

2002-09-01

Contact flexible microstrip applicator (CFMA) is a new light-weight microstrip applicator type for superficial and deep local hyperthermia. Typical specimens are developed for operation at frequencies of 434, 70, 40, and 27 MHz. The main common features of CFMA, namely, their flexibility and light weight, as well as their aperture dimensions slightly depend on the operating frequency. Two antenna types are used in CFMAs: inductive antennas with a radiating plane electrical dipole at microwaves, and coplanar capacitive antennas, providing depression of the normal component of the electrical field in the very high-frequency (VHF) and high-frequency (HF) range. The flexibility of the applicators enables one to conform them with curved surfaces. In a bent state of the applicators there arises a focusing effect of energy deposition in deeper located tissues due to linear polarization of the irradiated electromagnetic (EM) field, inherent in CFMA. All CFMA are integrated with silicon water boluses which serve as a matching element, so as a skin cooling agent. Due to this and to the predominance of the tangential electrical component in the radiated EM field, no fat overheating effects are noticed, as a rule. The aperture of the developed applicators overlap the range 160-630 cm2 providing effective heating field sizes (EFSs) 64-400 cm2, respectively. The most bulky CFMAs with an aperture of (21 x 29) cm2 operating at the frequency of 434 MHz weigh 0.8 kg and 2.5 kg at 27 MHz. Phenomenological analysis of the radiating systems, as well as experimental evaluation of the applicators are presented. CFMAs operating at frequencies of 434 and 40 MHz are used in clinical practice. CFMA at 70 and 27 MHz are subjected to laboratory clinical investigations.

Application of machine learning algorithms for clinical predictive modeling: a data-mining approach in SCT.

PubMed

Shouval, R; Bondi, O; Mishan, H; Shimoni, A; Unger, R; Nagler, A

2014-03-01

Data collected from hematopoietic SCT (HSCT) centers are becoming more abundant and complex owing to the formation of organized registries and incorporation of biological data. Typically, conventional statistical methods are used for the development of outcome prediction models and risk scores. However, these analyses carry inherent properties limiting their ability to cope with large data sets with multiple variables and samples. Machine learning (ML), a field stemming from artificial intelligence, is part of a wider approach for data analysis termed data mining (DM). It enables prediction in complex data scenarios, familiar to practitioners and researchers. Technological and commercial applications are all around us, gradually entering clinical research. In the following review, we would like to expose hematologists and stem cell transplanters to the concepts, clinical applications, strengths and limitations of such methods and discuss current research in HSCT. The aim of this review is to encourage utilization of the ML and DM techniques in the field of HSCT, including prediction of transplantation outcome and donor selection.

Adiabatic particle motion in a nearly drift-free magnetic field - Application to the geomagnetic tail

NASA Technical Reports Server (NTRS)

Stern, D. P.

1978-01-01

An investigation is made of the adiabatic particle motion occurring in an almost drift-free magnetic field. The dependence of the mean drift velocity on the equatorial pitch angle and the variation of the local drift velocity along the trajectories is studied. The fields considered are two-dimensional and resemble the geomagnetic tail. Derivations are presented for instantaneous and average drift velocities, bounce times, longitudinal invariants, and approximations to the adiabatic Hamiltonian. As expected, the mean drift velocity is significantly smaller than the instantaneous drift velocities found at typical points on the trajectory. The slow drift indicates that particles advance in the dawn-dusk direction rather slowly in the plasma sheet of the magnetospheric tail.

Orbital effect for the Fulde-Ferrell-Larkin-Ovchinnikov phase in a quasi-two-dimensional superconductor in a parallel magnetic field

NASA Astrophysics Data System (ADS)

Lebed, A. G.

2018-04-01

We theoretically study the orbital destructive effect against superconductivity in a parallel magnetic field in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO or LOFF) phase at zero temperature in a quasi-two-dimensional (Q2D) conductor. We demonstrate that at zero temperature a special parameter, λ =l⊥(H ) /d , is responsible for strength of the orbital effect, where l⊥(H ) is a typical "size" of the quasiclassical electron orbit in a magnetic field and d is the interplane distance. We discuss applications of our results to the existing experiments on the FFLO phase in the organic Q2D conductors κ -(ET) 2Cu (NCS) 2 and κ -(ET) 2Cu [N (CN) 2] Cl .

Applications and Mechanisms of Ionic Liquids in Whole-Cell Biotransformation

PubMed Central

Fan, Lin-Lin; Li, Hong-Ji; Chen, Qi-He

2014-01-01

Ionic liquids (ILs), entirely composed of cations and anions, are liquid solvents at room temperature. They are interesting due to their low vapor pressure, high polarity and thermostability, and also for the possibility to fine-tune their physicochemical properties through modification of the chemical structures of their cations or anions. In recent years, ILs have been widely used in biotechnological fields involving whole-cell biotransformations of biodiesel or biomass, and organic compound synthesis with cells. Research studies in these fields have increased from the past decades and compared to the typical solvents, ILs are the most promising alternative solvents for cell biotransformations. However, there are increasing limitations and new challenges in whole-cell biotransformations with ILs. There is little understanding of the mechanisms of ILs’ interactions with cells, and much remains to be clarified. Further investigations are required to overcome the drawbacks of their applications and to broaden their application spectrum. This work mainly reviews the applications of ILs in whole-cell biotransformations, and the possible mechanisms of ILs in microbial cell biotransformation are proposed and discussed. PMID:25007820

Applications and mechanisms of ionic liquids in whole-cell biotransformation.

PubMed

Fan, Lin-Lin; Li, Hong-Ji; Chen, Qi-He

2014-07-09

Ionic liquids (ILs), entirely composed of cations and anions, are liquid solvents at room temperature. They are interesting due to their low vapor pressure, high polarity and thermostability, and also for the possibility to fine-tune their physicochemical properties through modification of the chemical structures of their cations or anions. In recent years, ILs have been widely used in biotechnological fields involving whole-cell biotransformations of biodiesel or biomass, and organic compound synthesis with cells. Research studies in these fields have increased from the past decades and compared to the typical solvents, ILs are the most promising alternative solvents for cell biotransformations. However, there are increasing limitations and new challenges in whole-cell biotransformations with ILs. There is little understanding of the mechanisms of ILs' interactions with cells, and much remains to be clarified. Further investigations are required to overcome the drawbacks of their applications and to broaden their application spectrum. This work mainly reviews the applications of ILs in whole-cell biotransformations, and the possible mechanisms of ILs in microbial cell biotransformation are proposed and discussed.

Effects of nitrogen application rate, nitrogen synergist and biochar on nitrous oxide emissions from vegetable field in south China.

PubMed

Yi, Qiong; Tang, Shuanghu; Fan, Xiaolin; Zhang, Mu; Pang, Yuwan; Huang, Xu; Huang, Qiaoyi

2017-01-01

Globally, vegetable fields are the primary source of greenhouse gas emissions. A closed-chamber method together with gas chromatography was used to measure the fluxes of nitrous oxide (N2O) emissions in typical vegetable fields planted with four vegetables sequentially over time in the same field: endive, lettuce, cabbage and sweet corn. Results showed that N2O fluxes occurred in pulses with the N2O emission peak varying greatly among the crops. In addition, N2O emissions were linearly associated with the nitrogen (N) application rate (r = 0.8878, n = 16). Excessive fertilizer N application resulted in N loss through nitrous oxide gas emitted from the vegetable fields. Compared with a conventional fertilization (N2) treatment, the cumulative N2O emissions decreased significantly in the growing seasons of four plant species from an nitrogen synergist (a nitrification inhibitor, dicyandiamide and biochar treatments by 34.6% and 40.8%, respectively. However, the effects of biochar on reducing N2O emissions became more obvious than that of dicyandiamide over time. The yield-scaled N2O emissions in consecutive growing seasons for four species increased with an increase in the N fertilizer application rate, and with continuous application of N fertilizer. This was especially true for the high N fertilizer treatment that resulted in a risk of yield-scaled N2O emissions. Generally, the additions of dicyandiamide and biochar significantly decreased yield-scaled N2O-N emissions by an average of 45.9% and 45.7%, respectively, compared with N2 treatment from the consecutive four vegetable seasons. The results demonstrated that the addition of dicyandiamide or biochar in combination with application of a rational amount of N could provide the best strategy for the reduction of greenhouse gas emissions in vegetable field in south China.

Effects of nitrogen application rate, nitrogen synergist and biochar on nitrous oxide emissions from vegetable field in south China

PubMed Central

Zhang, Mu; Pang, Yuwan; Huang, Xu; Huang, Qiaoyi

2017-01-01

Globally, vegetable fields are the primary source of greenhouse gas emissions. A closed-chamber method together with gas chromatography was used to measure the fluxes of nitrous oxide (N2O) emissions in typical vegetable fields planted with four vegetables sequentially over time in the same field: endive, lettuce, cabbage and sweet corn. Results showed that N2O fluxes occurred in pulses with the N2O emission peak varying greatly among the crops. In addition, N2O emissions were linearly associated with the nitrogen (N) application rate (r = 0.8878, n = 16). Excessive fertilizer N application resulted in N loss through nitrous oxide gas emitted from the vegetable fields. Compared with a conventional fertilization (N2) treatment, the cumulative N2O emissions decreased significantly in the growing seasons of four plant species from an nitrogen synergist (a nitrification inhibitor, dicyandiamide and biochar treatments by 34.6% and 40.8%, respectively. However, the effects of biochar on reducing N2O emissions became more obvious than that of dicyandiamide over time. The yield-scaled N2O emissions in consecutive growing seasons for four species increased with an increase in the N fertilizer application rate, and with continuous application of N fertilizer. This was especially true for the high N fertilizer treatment that resulted in a risk of yield-scaled N2O emissions. Generally, the additions of dicyandiamide and biochar significantly decreased yield-scaled N2O-N emissions by an average of 45.9% and 45.7%, respectively, compared with N2 treatment from the consecutive four vegetable seasons. The results demonstrated that the addition of dicyandiamide or biochar in combination with application of a rational amount of N could provide the best strategy for the reduction of greenhouse gas emissions in vegetable field in south China. PMID:28419127

Fusion of current technologies with real-time 3D MEMS ladar for novel security and defense applications

NASA Astrophysics Data System (ADS)

Siepmann, James P.

2006-05-01

Through the utilization of scanning MEMS mirrors in ladar devices, a whole new range of potential military, Homeland Security, law enforcement, and civilian applications is now possible. Currently, ladar devices are typically large (>15,000 cc), heavy (>15 kg), and expensive (>$100,000) while current MEMS ladar designs are more than a magnitude less, opening up a myriad of potential new applications. One such application with current technology is a GPS integrated MEMS ladar unit, which could be used for real-time border monitoring or the creation of virtual 3D battlefields after being dropped or propelled into hostile territory. Another current technology that can be integrated into a MEMS ladar unit is digital video that can give high resolution and true color to a picture that is then enhanced with range information in a real-time display format that is easier for the user to understand and assimilate than typical gray-scale or false color images. The problem with using 2-axis MEMS mirrors in ladar devices is that in order to have a resonance frequency capable of practical real-time scanning, they must either be quite small and/or have a low maximum tilt angle. Typically, this value has been less than (< or = to 10 mg-mm2-kHz2)-degrees. We have been able to solve this problem by using angle amplification techniques that utilize a series of MEMS mirrors and/or a specialized set of optics to achieve a broad field of view. These techniques and some of their novel applications mentioned will be explained and discussed herein.

Plane-wave decomposition by spherical-convolution microphone array

NASA Astrophysics Data System (ADS)

Rafaely, Boaz; Park, Munhum

2004-05-01

Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.

Handheld directional reflectometer: an angular imaging device to measure BRDF and HDR in real time

NASA Astrophysics Data System (ADS)

Mattison, Phillip R.; Dombrowski, Mark S.; Lorenz, James M.; Davis, Keith J.; Mann, Harley C.; Johnson, Philip; Foos, Bryan

1998-10-01

Many applications require quantitative measurements of surface light scattering, including quality control on production lines, inspection of painted surfaces, inspection of field repairs, etc. Instruments for measuring surface scattering typically fall into two main categories, namely bidirectional reflectometers, which measure the angular distribution of scattering, and hemispherical directional reflectometers, which measure the total scattering into the hemisphere above the surface. Measurement of the bi-directional reflectance distribution function (BRDF) gives the greatest insight into how light is scattered from a surface. Measurements of BRDF, however, are typically very lengthy measurements taken by moving a source and detector to map the scattering. Since BRDF has four angular degrees of freedom, such measurements can require hours to days to complete. Instruments for measuring BRDF are also typically laboratory devices, although a field- portable bi-directional reflectometer does exist. Hemispherical directional reflectance (HDR) is a much easier measurement to make, although care must be taken to use the proper methodology when measuring at wavelengths beyond 10 micrometer, since integrating spheres (typically used to make such measurements) are very energy inefficient and lose their integrating properties at very long wavelengths. A few field- portable hemispherical directional reflectometers do exist, but typically measure HDR only at near-normal angles. Boeing Defense and Space Group and Surface Optics Corporation, under a contract from the Air Force Research Laboratory, have developed a new hand-held instrument capable of measuring both BRDF and HDR using a unique, patented angular imaging technique. A combination of an hemi-ellipsoidal mirror and an additional lens translate the angular scatter from a surface into a two-dimensional spatial distribution, which is recorded by an imaging array. This configuration fully maps the scattering from a half-hemisphere above the surface with more than 30,000 angularly-resolved points and update rates to 60 measurements per second. The instrument then computes HDR from the measured BDR. For ease of use, the instrument can also compare both the BRDF and HDR to preset limits, generating a Pass/Fail indicator for HDR and a high-acceptable-low image display of BRDF. Beam incidence elevation is variable from normal incidence ((theta) equals 0 degrees) to 5 degrees off grazing ((theta) equals 85 degrees), while scattering is measured to nearly 90 degrees off normal. Such capability is extremely important for any application requiring knowledge of surface appearance at oblique viewing angles. The current instrument operates over the range of 3 micrometer to 12 micrometer, with extension into the visible band possible.

Applications of low altitude photogrammetry for morphometry, displacements, and landform modeling

NASA Astrophysics Data System (ADS)

Gomez, F. G.; Polun, S. G.; Hickcox, K.; Miles, C.; Delisle, C.; Beem, J. R.

2016-12-01

Low-altitude aerial surveying is emerging as a tool that greatly improves the ease and efficiency of measuring landforms for quantitative geomorphic analyses. High-resolution, close-range photogrammetry produces dense, 3-dimensional point clouds that facilitate the construction of digital surface models, as well as a potential means of classifying ground targets using spatial structure. This study presents results from recent applications of UAS-based photogrammetry, including high resolution surface morphometry of a lava flow, repeat-pass applications to mass movements, and fault scarp degradation modeling. Depending upon the desired photographic resolution and the platform/payload flown, aerial photos are typically acquired at altitudes of 40 - 100 meters above the ground surface. In all cases, high-precision ground control points are key for accurate (and repeatable) orientation - relying on low-precision GPS coordinates (whether on the ground or geotags in the aerial photos) typically results in substantial rotations (tilt) of the reference frame. Using common ground control points between repeat surveys results in matching point clouds with RMS residuals better than 10 cm. In arid regions, the point cloud is used to assess lava flow surface roughness using multi-scale measurements of point cloud dimensionality. For the landslide study, the point cloud provides a basis for assessing possible displacements. In addition, the high resolution orthophotos facilitate mapping of fractures and their growth. For neotectonic applications, we compare fault scarp modeling results from UAV-derived point clouds versus field-based surveys (kinematic GPS and electronic distance measurements). In summary, there is a wide ranging toolbox of low-altitude aerial platforms becoming available for field geoscientists. In many instances, these tools will present convenience and reduced cost compared with the effort and expense to contract acquisitions of aerial imagery.

Mechanochemical Synthesis of Carbon Fluorides

DTIC Science & Technology

2011-02-16

REPORT DOCUMENTATION PAGE Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 Form Approved OMB No. 0704-0188 The public reporting burden...Wishvender K. Behl APPROVED FOR PUBLIC RELEASE • Li/ CFx batteries are being developed to replace the currently fielded BA5590 and 5390 primary batteries...Li/ CFx batteries have twice the specific energy and energy density of Li/SO2 batteries. • This chemistry, typically used for applications at 1000

Design and Application of a Larval Fish Trap

DTIC Science & Technology

1994-05-01

Sedimentation processes should be grouped into the broad categories of *local’ and *general" processes. Local processes are those occurring over a relatively...in terms of group symbols and typical group nanie, by a field expedient procedure that uses the USCS. Soils possessing characteristics of two groups ...are designated by combinations of group symbols. For example, a GW-GC soil is a well- graded gravel-sand mixture with clay binder. A wetland soil may

Transport of Space Environment Electrons: A Simplified Rapid-Analysis Computational Procedure

NASA Technical Reports Server (NTRS)

Nealy, John E.; Anderson, Brooke M.; Cucinotta, Francis A.; Wilson, John W.; Katz, Robert; Chang, C. K.

2002-01-01

A computational procedure for describing transport of electrons in condensed media has been formulated for application to effects and exposures from spectral distributions typical of electrons trapped in planetary magnetic fields. The procedure is based on earlier parameterizations established from numerous electron beam experiments. New parameterizations have been derived that logically extend the domain of application to low molecular weight (high hydrogen content) materials and higher energies (approximately 50 MeV). The production and transport of high energy photons (bremsstrahlung) generated in the electron transport processes have also been modeled using tabulated values of photon production cross sections. A primary purpose for developing the procedure has been to provide a means for rapidly performing numerous repetitive calculations essential for electron radiation exposure assessments for complex space structures. Several favorable comparisons have been made with previous calculations for typical space environment spectra, which have indicated that accuracy has not been substantially compromised at the expense of computational speed.

Is an Apple Magnetic: Magnetic Response of Everyday Materials Supporting Views About the Nature of Science

NASA Astrophysics Data System (ADS)

Laumann, Daniel

2017-03-01

Magnetism and its various applications are essential for our daily life and for many technological developments. The term magnetism is almost always used as a synonym for ferromagnetism. However, the magnetic properties of the elements of the periodic table indicate that the vast majority of elements are not ferromagnetic, but rather, diamagnetic or paramagnetic. Typically, only ferromagnetism is discussed in classrooms, which can create a distorted picture. This article supplies the further development of an experiment demonstrating the dia- and paramagnetic properties with an electronic balance and a neodymium magnet. It focuses on an investigation of ordinary materials that occur in pupils' everyday environment. The experiment is applicable both for a quantitative measurement of the magnetic (volume) susceptibility χV and can serve as a phenomenological approach to dia- and paramagnetism. Moreover, it encourages a discussion about typical beliefs regarding the nature of science, comparing the behavior of common objects in weak and in strong magnetic fields.

Lessons Learned from Six Decades of Radio Polarimetry

NASA Astrophysics Data System (ADS)

Wiesemeyer, Helmut; Güsten, R.; Kreysa, E.; Menten, K. M.; Morris, D.; Paubert, G.; Pillai, T.; Sievers, A.; Thum, C.

2018-01-01

The characterization of polarized emission from continuum radiation and spectral lines across large-scale galactic and extragalactic fields is a typical application of single-dish telescopes, from radio to far-infrared wavelengths. Despite its high analytical value, in many cases polarimetry was added to the design specifications of telescopes and their frontends only in advanced development stages. While in some situations the instrumental contamination of the Stokes parameters can be corrected, this becomes increasingly difficult for extended fields. This contribution summarizes the current situation at mm/submm telescopes. Strategies for post-observing polarization calibration are presented as well as methods to optimize the components in the beam path.

Application Research of Fault Tree Analysis in Grid Communication System Corrective Maintenance

NASA Astrophysics Data System (ADS)

Wang, Jian; Yang, Zhenwei; Kang, Mei

2018-01-01

This paper attempts to apply the fault tree analysis method to the corrective maintenance field of grid communication system. Through the establishment of the fault tree model of typical system and the engineering experience, the fault tree analysis theory is used to analyze the fault tree model, which contains the field of structural function, probability importance and so on. The results show that the fault tree analysis can realize fast positioning and well repairing of the system. Meanwhile, it finds that the analysis method of fault tree has some guiding significance to the reliability researching and upgrading f the system.

On the theory of hysteretic magnetostriction of soft ferrogels

NASA Astrophysics Data System (ADS)

Zubarev, Andrey; Chirikov, Dmitry; Stepanov, Gennady; Borin, Dmitry; Lopez-Lopez, M. T.

2018-05-01

The paper deals with theoretical study of hysteretic magnetostriction of soft ferrogels - composite materials, consisting of the micron-sized magnetizable particles embedded into gel matrices. It is supposed that initially, before application of an external magnetic field, the particles are homogeneously and isotropically distributed in an elastic matrix. The theoretical explanation of the hysteresis phenomena is based on the conception that, under the field action, the particles rearrange into the linear chain-like aggregates. The typical length of the chains is determined by the competition between the force of magnetic attraction of the particles and the force of elastic deformation of the matrix.

Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images.

PubMed

Watson, Jeffrey R; Gainer, Christian F; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G Michael; Anton, Rein; Romanowski, Marek

2015-10-01

Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures.

Modulating the band gap of a boron nitride bilayer with an external electric field for photocatalyst

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

Tang, Y. R.; Cao, J. X., E-mail: jxcao@xtu.edu.cn; Zhang, Y.

2016-05-21

By virtue of first principle calculations, we propose an approach to reduce the band gap of layered semiconductors through the application of external electric fields for photocatalysis. As a typical example, the band gap of a boron nitride (BN) bilayer was reduced in the range from 4.45 eV to 0.3 eV by varying the external electric field strength. More interestingly, it is found that the uppermost valence band and the lowest conduction band are dominated by the N-p{sub z} and B-p{sub z} from different layers of the BN sheet, which suggests a wonderful photoexcited electron and hole separation system for photocatalysis. Ourmore » results imply that the strong external electric field can present an abrupt polarized surface.« less

Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images

NASA Astrophysics Data System (ADS)

Watson, Jeffrey R.; Gainer, Christian F.; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G. Michael, Jr.; Anton, Rein; Romanowski, Marek

2015-10-01

Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures.

An Experimental Study of the Effects of A Rotating Magnetic Field on Electrically Conducting Aqueous Solutions

NASA Technical Reports Server (NTRS)

Ramachandran Narayanan; Mazuruk, Konstantin

1998-01-01

The use of a rotating magnetic field for stirring metallic melts has been a commonly adopted practice for a fairly long period. The elegance of the technique stems from its non-intrusive nature and the intense stirring it can produce in an electrically conducting medium. A further application of the method in recent times has been in the area of crystal growth from melts (e.g. germanium). The latter experiments have been mainly research oriented in order to understand the basic physics of the process and to establish norms for optimizing such a technique for the commercial production of crystals. When adapted for crystal growth applications, the rotating magnetic field is used to induce a slow flow or rotation in the melt which in effect significantly curtails temperature field oscillations in the melt. These oscillations are known to cause dopant striations and thereby inhomogeneities in the grown crystal that essentially degrades the crystal quality. The applied field strength is typically of the order of milli-Teslas with a frequency range between 50-400 Hz. In this investigation, we report findings from experiments that explore the feasibility of applying a rotating magnetic field to aqueous salt solutions, that are characterized by conductivities that are several orders of magnitude smaller than semi-conductor melts. The aim is to study the induced magnetic field and consequently the induced flow in such in application. Detailed flow field description obtained through non-intrusive particle displacement tracking will be reported along with an analytical assessment of the results. It is anticipated that the obtained results will facilitate in establishing a parameter range over which the technique can be applied to obtain a desired flow field distribution. This method can find applicability in the growth of crystals from aqueous solutions and give an experimenter another controllable parameter towards improving the quality of the grown crystal.

Gravitational Thermodynamics for Interstellar Gas and Weakly Degenerate Quantum Gas

NASA Astrophysics Data System (ADS)

Zhu, Ding Yu; Shen, Jian Qi

2016-03-01

The temperature distribution of an ideal gas in gravitational fields has been identified as a longstanding problem in thermodynamics and statistical physics. According to the principle of entropy increase (i.e., the principle of maximum entropy), we apply a variational principle to the thermodynamical entropy functional of an ideal gas and establish a relationship between temperature gradient and gravitational field strength. As an illustrative example, the temperature and density distributions of an ideal gas in two simple but typical gravitational fields (i.e., a uniform gravitational field and an inverse-square gravitational field) are considered on the basis of entropic and hydrostatic equilibrium conditions. The effect of temperature inhomogeneity in gravitational fields is also addressed for a weakly degenerate quantum gas (e.g., Fermi and Bose gas). The present gravitational thermodynamics of a gas would have potential applications in quantum fluids, e.g., Bose-Einstein condensates in Earth’s gravitational field and the temperature fluctuation spectrum in cosmic microwave background radiation.

MoS2‐Based Nanocomposites for Electrochemical Energy Storage

PubMed Central

Wang, Tianyi; Chen, Shuangqiang; Xue, Huaiguo

2016-01-01

Typical layered transition‐metal chalcogenide materials, in particular layered molybdenum disulfide (MoS2) nanocomposites, have attracted increasing attention in recent years due to their excellent chemical and physical properties in various research fieldsHere, a general overview of synthetic MoS2 based nanocomposites via different preparation approaches and their applications in energy storage devices (Li‐ion battery, Na‐ion battery, and supercapacitor) is presented. The relationship between morphologies and the electrochemical performances of MoS2‐based nanocomposites in the three typical and promising rechargeable systems is also discussed. Finally, perspectives on major challenges and opportunities faced by MoS2‐based materials to address the practical problems of MoS2‐based materials are presented. PMID:28251051

MAGMA: analysis of two-channel microarrays made easy.

PubMed

Rehrauer, Hubert; Zoller, Stefan; Schlapbach, Ralph

2007-07-01

The web application MAGMA provides a simple and intuitive interface to identify differentially expressed genes from two-channel microarray data. While the underlying algorithms are not superior to those of similar web applications, MAGMA is particularly user friendly and can be used without prior training. The user interface guides the novice user through the most typical microarray analysis workflow consisting of data upload, annotation, normalization and statistical analysis. It automatically generates R-scripts that document MAGMA's entire data processing steps, thereby allowing the user to regenerate all results in his local R installation. The implementation of MAGMA follows the model-view-controller design pattern that strictly separates the R-based statistical data processing, the web-representation and the application logic. This modular design makes the application flexible and easily extendible by experts in one of the fields: statistical microarray analysis, web design or software development. State-of-the-art Java Server Faces technology was used to generate the web interface and to perform user input processing. MAGMA's object-oriented modular framework makes it easily extendible and applicable to other fields and demonstrates that modern Java technology is also suitable for rather small and concise academic projects. MAGMA is freely available at www.magma-fgcz.uzh.ch.

Field dissipation and risk assessment of typical personal care products TCC, TCS, AHTN and HHCB in biosolid-amended soils.

PubMed

Chen, Feng; Ying, Guang-Guo; Ma, Yi-Bing; Chen, Zhi-Feng; Lai, Hua-Jie; Peng, Feng-Jiao

2014-02-01

The antimicrobial agents triclocarban (TCC) and triclosan (TCS) and synthetic musks AHTN (Tonalide) and HHCB (Galaxolide) are widely used in many personal care products. These compounds may release into the soil environment through biosolid application to agricultural land and potentially affect soil organisms. This paper aimed to investigate accumulation, dissipation and potential risks of TCC, TCS, AHTN and HHCB in biosolid-amended soils of the three field trial sites (Zhejiang, Hunan and Shandong) with three treatments (CK: control without biosolid application, T1: single biosolid application, T2: repeated biosolid application every year). The one-year monitoring results showed that biosolids application could lead to accumulation of these four chemicals in the biosolid-amended soils, with the residual concentrations in the following order: TCC>TCS>AHTN>HHCB. Dissipation of TCC, TCS, AHTN and HHCB in the biosolid-amended soils followed the first-order kinetics model. Half-lives for TCC, TCS, AHTN and HHCB under the field conditions of Shandong site were 191, 258, 336 and 900 days for T1, and 51, 106, 159 and 83 days for T2, respectively. Repeated applications of biosolid led to accumulation of these personal care products and result in higher ecological risks. Based on the residual levels in the trial sites and limited toxicity data, high risks to soil organisms are expected for TCC and TCS, while low-medium risks for AHTN and HHCB. © 2013.

Comparison of greenhouse gas emissions from rice paddy fields under different nitrogen fertilization loads in Chongming Island, Eastern China.

PubMed

Zhang, Xianxian; Yin, Shan; Li, Yinsheng; Zhuang, Honglei; Li, Changsheng; Liu, Chunjiang

2014-02-15

Rice is one of the major crops of southern China and Southeast Asia. Rice paddies are one of the largest agricultural greenhouse gas (GHG) sources in this region because of the application of large quantities of nitrogen (N) fertilizers to the plants. In particular, the production of methane (CH4) is a concern. Investigating a reasonable amount of fertilizers to apply to plants is essential to maintaining high yields while reducing GHG emissions. In this study, three levels of fertilizer application [high (300 kg N/ha), moderate (210 kg N/ha), and low (150 kg N/ha)] were designed to examine the effects of variation in N fertilizer application rate on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from the paddy fields in Chongming Island, Shanghai, China. The high level (300 kg N/ha) represented the typical practice adopted by the local farmers in the area. Maximum amounts of CH4 and N2O fluxes were observed upon high-level fertilizer application in the plots. Cumulative N2O emissions of 23.09, 40.10, and 71.08 mg N2O/m(2) were observed over the growing season in 2011 under the low-, moderate-, and high-level applications plots, respectively. The field data also indicated that soil temperatures at 5 and 10 cm soil depths significantly affected soil respiration; the relationship between Rs and soil temperature in this study could be described by an exponential model. Our study showed that reducing the high rate of fertilizer application is a feasible way of attenuating the global-warming potential while maintaining the optimum yield for the studied paddy fields. Copyright © 2013 Elsevier B.V. All rights reserved.

Information driving force and its application in agent-based modeling

NASA Astrophysics Data System (ADS)

Chen, Ting-Ting; Zheng, Bo; Li, Yan; Jiang, Xiong-Fei

2018-04-01

Exploring the scientific impact of online big-data has attracted much attention of researchers from different fields in recent years. Complex financial systems are typical open systems profoundly influenced by the external information. Based on the large-scale data in the public media and stock markets, we first define an information driving force, and analyze how it affects the complex financial system. The information driving force is observed to be asymmetric in the bull and bear market states. As an application, we then propose an agent-based model driven by the information driving force. Especially, all the key parameters are determined from the empirical analysis rather than from statistical fitting of the simulation results. With our model, both the stationary properties and non-stationary dynamic behaviors are simulated. Considering the mean-field effect of the external information, we also propose a few-body model to simulate the financial market in the laboratory.

The ePLAS code for Ignition Studies

NASA Astrophysics Data System (ADS)

Faehl, R. J.; Mason, R. J.; Kirkpatrick, R. C.

2012-10-01

The ePLAS code is a multi-fluid/PIC hybrid developing self-consistent E & B-fields by the Implicit Moment Method for stable calculations of high density plasma problems with voids on the electron Courant time scale. See: http://www.researchapplicationscorp.com. Here, we outline typical applications to: 1) short pulse driven electron transport along void (or high Z) insulated wires, and 2) the 2D development of shock ignition pressure peaks with B-fields. We outline the code's recent inclusion of SESAME EOS data, a DT/DD burn capability, a new option for K-alpha imaging of modeling output, and demonstrate a foil expansion tracked with either fluid or particle ions. Also, we describe a new super-hybrid extension of our implicit solver that permits full target dynamics studies on the ion Courant scale. Finally, we will touch on the very recent application of ePLAS to possible non-local/kinetic hydro effects NIF capsules.

The effect of poultry manure application rate and AlCl(3) treatment on bacterial fecal indicators in runoff.

PubMed

Brooks, J P; Adeli, A; McLaughlin, M R; Miles, D M

2012-12-01

Increasing costs associated with inorganic fertilizer have led to widespread use of broiler litter. Proper land application, typically limiting nutrient loss, is essential to protect surface water. This study was designed to evaluate litter-borne microbial runoff (heterotrophic plate count bacteria, staphylococci, Escherichia coli, enterococci, and Clostridium perfringens) while applying typical nutrient-control methods. Field studies were conducted in which plots with high and low litter rates, inorganic fertilizer, AlCl(3)-treated litter, and controls were rained on five times using a rain generator. Overall, microbial runoff from poultry litter applied plots was consistently greater (2-5 log(10) plot(-1)) than controls. No appreciable effect on microbial runoff was noted from variable litter application rate or AlCl(3) treatments, though rain event, not time, significantly affected runoff load. C. perfringens and staphylococci runoff were consistently associated with poultry litter application, during early rain events, while other indicators were unreliable. Large microbial runoff pulses were observed, ranging from 10(2) to 10(10) CFU plot(-1); however, only a small fraction of litter-borne microbes were recoverable in runoff. This study indicated that microbial runoff from litter-applied plots can be substantial, and that methods intended to reduce nutrient losses do not necessarily reduce microbial runoff.

Numerical solution of the Navier-Stokes equations about three-dimensional configurations: A survey

NASA Technical Reports Server (NTRS)

Holst, Terry L.

1987-01-01

The numerical solution of the Navier-Stokes equations about three-dimensional configurations is reviewed. Formulational and computational requirements for the various Navier-Stokes approaches are examined for typical problems including the viscous flow field solution about a complete aerospace vehicle. Recent computed results, with experimental comparisons when available, are presented to highlight the presentation. The future of Navier-Stokes applications in three-dimensions is seen to be rapidly expanding across a broad front including internal and external flows, and flows across the entire speed regime from incompressible to hypersonic applications. Prospects for the future are described and recommendations for areas of concentrated research are indicated.

Digital Image Correlation Engine

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

Turner, Dan; Crozier, Paul; Reu, Phil

DICe is an open source digital image correlation (DIC) tool intended for use as a module in an external application or as a standalone analysis code. It's primary capability is computing full-field displacements and strains from sequences of digital These images are typically of a material sample undergoing a materials characterization experiment, but DICe is also useful for other applications (for example, trajectory tracking). DICe is machine portable (Windows, Linux and Mac) and can be effectively deployed on a high performance computing platform. Capabilities from DICe can be invoked through a library interface, via source code integration of DICe classesmore » or through a graphical user interface.« less

COPASI and its applications in biotechnology.

PubMed

Bergmann, Frank T; Hoops, Stefan; Klahn, Brian; Kummer, Ursula; Mendes, Pedro; Pahle, Jürgen; Sahle, Sven

2017-11-10

COPASI is software used for the creation, modification, simulation and computational analysis of kinetic models in various fields. It is open-source, available for all major platforms and provides a user-friendly graphical user interface, but is also controllable via the command line and scripting languages. These are likely reasons for its wide acceptance. We begin this review with a short introduction describing the general approaches and techniques used in computational modeling in the biosciences. Next we introduce the COPASI package, and its capabilities, before looking at typical applications of COPASI in biotechnology. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Modeling Longitudinal Data Containing Non-Normal Within Subject Errors

NASA Technical Reports Server (NTRS)

Feiveson, Alan; Glenn, Nancy L.

2013-01-01

The mission of the National Aeronautics and Space Administration’s (NASA) human research program is to advance safe human spaceflight. This involves conducting experiments, collecting data, and analyzing data. The data are longitudinal and result from a relatively few number of subjects; typically 10 – 20. A longitudinal study refers to an investigation where participant outcomes and possibly treatments are collected at multiple follow-up times. Standard statistical designs such as mean regression with random effects and mixed–effects regression are inadequate for such data because the population is typically not approximately normally distributed. Hence, more advanced data analysis methods are necessary. This research focuses on four such methods for longitudinal data analysis: the recently proposed linear quantile mixed models (lqmm) by Geraci and Bottai (2013), quantile regression, multilevel mixed–effects linear regression, and robust regression. This research also provides computational algorithms for longitudinal data that scientists can directly use for human spaceflight and other longitudinal data applications, then presents statistical evidence that verifies which method is best for specific situations. This advances the study of longitudinal data in a broad range of applications including applications in the sciences, technology, engineering and mathematics fields.

Chemically reacting supersonic flow calculation using an assumed PDF model

NASA Technical Reports Server (NTRS)

Farshchi, M.

1990-01-01

This work is motivated by the need to develop accurate models for chemically reacting compressible turbulent flow fields that are present in a typical supersonic combustion ramjet (SCRAMJET) engine. In this paper the development of a new assumed probability density function (PDF) reaction model for supersonic turbulent diffusion flames and its implementation into an efficient Navier-Stokes solver are discussed. The application of this model to a supersonic hydrogen-air flame will be considered.

Generation of three wide frequency bands within a single white-light cavity

NASA Astrophysics Data System (ADS)

Othman, Anas; Yevick, David; Al-Amri, M.

2018-04-01

We theoretically investigate the double-Λ scheme inside a Fabry-Pérot cavity employing a weak probe beam and two strong driving fields together with an incoherent pumping mechanism. By generating analytical expressions for the susceptibility and applying the white-light cavity conditions, we devise a procedure that reaches the white-light condition at a smaller gas density than the values typically cited in similar previous studies. Further, when the intensities of the two driving fields are equal, a single giant white band is obtained, while for unequal driving fields three white bands can be present in the cavity. Two additional techniques are then advanced for generating three white bands and a method is described for displacing the center frequency of the bands. Finally, some potential applications are suggested.

Radiation Protection

NASA Astrophysics Data System (ADS)

Grupen, Claus

Radiation protection is a very important aspect for the application of particle detectors in many different fields, like high energy physics, medicine, materials science, oil and mineral exploration, and arts, to name a few. The knowledge of radiation units, the experience with shielding, and information on biological effects of radiation are vital for scientists handling radioactive sources or operating accelerators or X-ray equipment. This article describes the modern radiation units and their conversions to older units which are still in use in many countries. Typical radiation sources and detectors used in the field of radiation protection are presented. The legal regulations in nearly all countries follow closely the recommendations of the International Commission on Radiological Protection (ICRP). Tables and diagrams with relevant information on the handling of radiation sources provide useful data for the researcher working in this field.

Multicore fibre photonic lanterns for precision radial velocity Science

NASA Astrophysics Data System (ADS)

Gris-Sánchez, Itandehui; Haynes, Dionne M.; Ehrlich, Katjana; Haynes, Roger; Birks, Tim A.

2018-04-01

Incomplete fibre scrambling and fibre modal noise can degrade high-precision spectroscopic applications (typically high spectral resolution and high signal to noise). For example, it can be the dominating error source for exoplanet finding spectrographs, limiting the maximum measurement precision possible with such facilities. This limitation is exacerbated in the next generation of infra-red based systems, as the number of modes supported by the fibre scales inversely with the wavelength squared and more modes typically equates to better scrambling. Substantial effort has been made by major research groups in this area to improve the fibre link performance by employing non-circular fibres, double scramblers, fibre shakers, and fibre stretchers. We present an original design of a multicore fibre (MCF) terminated with multimode photonic lantern ports. It is designed to act as a relay fibre with the coupling efficiency of a multimode fibre (MMF), modal stability similar to a single-mode fibre and low loss in a wide range of wavelengths (380 nm to 860 nm). It provides phase and amplitude scrambling to achieve a stable near field and far-field output illumination pattern despite input coupling variations, and low modal noise for increased stability for high signal-to-noise applications such as precision radial velocity (PRV) science. Preliminary results are presented for a 511-core MCF and compared with current state of the art octagonal fibre.

Albedo Neutron Dosimetry in a Deep Geological Disposal Repository for High-Level Nuclear Waste.

PubMed

Pang, Bo; Becker, Frank

2017-04-28

Albedo neutron dosemeter is the German official personal neutron dosemeter in mixed radiation fields where neutrons contribute to personal dose. In deep geological repositories for high-level nuclear waste, where neutrons can dominate the radiation field, it is of interest to investigate the performance of albedo neutron dosemeter in such facilities. In this study, the deep geological repository is represented by a shielding cask loaded with spent nuclear fuel placed inside a rock salt emplacement drift. Due to the backscattering of neutrons in the drift, issues concerning calibration of the dosemeter arise. Field-specific calibration of the albedo neutron dosemeter was hence performed with Monte Carlo simulations. In order to assess the applicability of the albedo neutron dosemeter in a deep geological repository over a long time scale, spent nuclear fuel with different ages of 50, 100 and 500 years were investigated. It was found out, that the neutron radiation field in a deep geological repository can be assigned to the application area 'N1' of the albedo neutron dosemeter, which is typical in reactors and accelerators with heavy shielding. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

PylotDB - A Database Management, Graphing, and Analysis Tool Written in Python

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

Barnette, Daniel W.

2012-01-04

PylotDB, written completely in Python, provides a user interface (UI) with which to interact with, analyze, graph data from, and manage open source databases such as MySQL. The UI mitigates the user having to know in-depth knowledge of the database application programming interface (API). PylotDB allows the user to generate various kinds of plots from user-selected data; generate statistical information on text as well as numerical fields; backup and restore databases; compare database tables across different databases as well as across different servers; extract information from any field to create new fields; generate, edit, and delete databases, tables, and fields;more » generate or read into a table CSV data; and similar operations. Since much of the database information is brought under control of the Python computer language, PylotDB is not intended for huge databases for which MySQL and Oracle, for example, are better suited. PylotDB is better suited for smaller databases that might be typically needed in a small research group situation. PylotDB can also be used as a learning tool for database applications in general.« less

An approach for detecting five typical vegetation types on the Chinese Loess Plateau using Landsat TM data.

PubMed

Wang, Zhi-Jie; Jiao, Ju-Ying; Lei, Bo; Su, Yuan

2015-09-01

Remote sensing can provide large-scale spatial data for the detection of vegetation types. In this study, two shortwave infrared spectral bands (TM5 and TM7) and one visible spectral band (TM3) of Landsat 5 TM data were used to detect five typical vegetation types (communities dominated by Bothriochloa ischaemum, Artemisia gmelinii, Hippophae rhamnoides, Robinia pseudoacacia, and Quercus liaotungensis) using 270 field survey data in the Yanhe watershed on the Loess Plateau. The relationships between 200 field data points and their corresponding radiance reflectance were analyzed, and the equation termed the vegetation type index (VTI) was generated. The VTI values of five vegetation types were calculated, and the accuracy was tested using the remaining 70 field data points. The applicability of VTI was also tested by the distribution of vegetation type of two small watersheds in the Yanhe watershed and field sample data collected from other regions (Ziwuling Region, Huangling County, and Luochuan County) on the Loess Plateau. The results showed that the VTI can effectively detect the five vegetation types with an average accuracy exceeding 80 % and a representativeness above 85 %. As a new approach for monitoring vegetation types using remote sensing at a larger regional scale, VTI can play an important role in the assessment of vegetation restoration and in the investigation of the spatial distribution and community diversity of vegetation on the Loess Plateau.

3D polarisation speckle as a demonstration of tensor version of the van Cittert-Zernike theorem for stochastic electromagnetic beams

NASA Astrophysics Data System (ADS)

Ma, Ning; Zhao, Juan; Hanson, Steen G.; Takeda, Mitsuo; Wang, Wei

2016-10-01

Laser speckle has received extensive studies of its basic properties and associated applications. In the majority of research on speckle phenomena, the random optical field has been treated as a scalar optical field, and the main interest has been concentrated on their statistical properties and applications of its intensity distribution. Recently, statistical properties of random electric vector fields referred to as Polarization Speckle have come to attract new interest because of their importance in a variety of areas with practical applications such as biomedical optics and optical metrology. Statistical phenomena of random electric vector fields have close relevance to the theories of speckles, polarization and coherence theory. In this paper, we investigate the correlation tensor for stochastic electromagnetic fields modulated by a depolarizer consisting of a rough-surfaced retardation plate. Under the assumption that the microstructure of the scattering surface on the depolarizer is as fine as to be unresolvable in our observation region, we have derived a relationship between the polarization matrix/coherency matrix for the modulated electric fields behind the rough-surfaced retardation plate and the coherence matrix under the free space geometry. This relation is regarded as entirely analogous to the van Cittert-Zernike theorem of classical coherence theory. Within the paraxial approximation as represented by the ABCD-matrix formalism, the three-dimensional structure of the generated polarization speckle is investigated based on the correlation tensor, indicating a typical carrot structure with a much longer axial dimension than the extent in its transverse dimension.

Arbitrary magnetic field gradient waveform correction using an impulse response based pre-equalization technique.

PubMed

Goora, Frédéric G; Colpitts, Bruce G; Balcom, Bruce J

2014-01-01

The time-varying magnetic fields used in magnetic resonance applications result in the induction of eddy currents on conductive structures in the vicinity of both the sample under investigation and the gradient coils. These eddy currents typically result in undesired degradations of image quality for MRI applications. Their ubiquitous nature has resulted in the development of various approaches to characterize and minimize their impact on image quality. This paper outlines a method that utilizes the magnetic field gradient waveform monitor method to directly measure the temporal evolution of the magnetic field gradient from a step-like input function and extracts the system impulse response. With the basic assumption that the gradient system is sufficiently linear and time invariant to permit system theory analysis, the impulse response is used to determine a pre-equalized (optimized) input waveform that provides a desired gradient response at the output of the system. An algorithm has been developed that calculates a pre-equalized waveform that may be accurately reproduced by the amplifier (is physically realizable) and accounts for system limitations including system bandwidth, amplifier slew rate capabilities, and noise inherent in the initial measurement. Significant improvements in magnetic field gradient waveform fidelity after pre-equalization have been realized and are summarized. Copyright © 2013 Elsevier Inc. All rights reserved.

Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images

PubMed Central

Watson, Jeffrey R.; Gainer, Christian F.; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G. Michael; Anton, Rein; Romanowski, Marek

2015-01-01

Abstract. Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures. PMID:26440760

Thermophotovoltaic systems for civilian and industrial applications in Japan

NASA Astrophysics Data System (ADS)

Yugami, Hiroo; Sasa, Hiromi; Yamaguchi, Masafumi

2003-05-01

The potential market for thermophotovoltaic (TPV) applications has been studied for civilian and industrial sectors in Japan. Comparing the performance of gas engines or turbines, as well as the underdeveloped power generation technologies such as fuel cells or chemical batteries, we have discussed the feasible application field of TPV systems to compete with those power generations. From the point of view of applicability for TPV systems in Japan, portable generators, co-generation systems and solar power plants are selected for our system analysis. The cost and performance targets of TPV systems for co-generation are also discussed by assuming a typical daily profile of electricity and hot water demands in Japanese homes. A progress report on the recent TPV research activities is given as well as a feasibility study concerning such TPV systems in Japan.

Faster sensitivity and non-antimonite permanent photoresist for MEMS

NASA Astrophysics Data System (ADS)

Misumi, Koichi; Saito, Koji; Yamanouchi, Atsushi; Senzaki, Takahiro; Okui, Toshiki; Honma, Hideo

2006-03-01

Micro Electro Mechanical Systems (MEMS) is a three-dimensional micro-fabrication technology based on photolithography. The fields of application are extensive and wide-ranging. Among the applications, those that have already acquired a large market include acceleration sensors for airbags of automobiles, pressure sensors for engine control, inkjet printer heads and thin film magnetic heads. The market is expected to further expand in the optic and biology-related fields in the future. In the MEMS field, the packaging accounts for the cost, and it is difficult to standardize due to the low production volume of highly specific technology application. A typical application in the MEMS process would be to conduct plating and etching (Deep RIE) through an intermediate layer of photoresist patterns, but there are cases where the photoresist itself is left therein as a permanent film. A photoresist composed of epoxy resin as the main component can form the permanent film through a catalyst of the optical cationic polymerizating initiator. In general, the optical cationic polymerizating initiator is of onium salt with antimonite as the anion group due to the nature of the hardening rate or the exposure energy. This paper presents the development status of a high sensitivity permanent photoresist made of epoxy resin as the main component with non-antimonite optical cationic polymerizating initiator with concerns to the impact to the environment and material for packaging.

Standard Practices for Usage of Inductive Magnetic Field Probes with Application to Electric Propulsion Testing

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Hill, Carrie S.

2013-01-01

Inductive magnetic field probes (also known as B-dot probes and sometimes as B-probes or magnetic probes) are useful for performing measurements in electric space thrusters and various plasma accelerator applications where a time-varying magnetic field is present. Magnetic field probes have proven to be a mainstay in diagnosing plasma thrusters where changes occur rapidly with respect to time, providing the means to measure the magnetic fields produced by time-varying currents and even an indirect measure of the plasma current density through the application of Ampère's law. Examples of applications where this measurement technique has been employed include pulsed plasma thrusters and quasi-steady magnetoplasmadynamic thrusters. The Electric Propulsion Technical Committee (EPTC) of the American Institute of Aeronautics and Astronautics (AIAA) was asked to assemble a Committee on Standards (CoS) for Electric Propulsion Testing. The assembled CoS was tasked with developing Standards and Recommended Practices for various diagnostic techniques used in the evaluation of plasma thrusters. These include measurements that can yield either global information related to a thruster and its performance or detailed, local data related to the specific physical processes occurring in the plasma. This paper presents a summary of the standard, describing the preferred methods for fabrication, calibration, and usage of inductive magnetic field probes for use in diagnosing plasma thrusters. Inductive magnetic field probes (also called B-dot probes throughout this document) are commonly used in electric propulsion (EP) research and testing to measure unsteady magnetic fields produced by time-varying currents. The B-dot probe is relatively simple in construction, and requires minimal cost, making it a low-cost technique that is readily accessible to most researchers. While relatively simple, the design of a B-dot probe is not trivial and there are many opportunities for errors in probe construction, calibration, and usage, and in the post-processing of data that is produced by the probe. There are typically several ways in which each of these steps can be approached, and different applications may require more or less vigorous attention to various issues.

Wide dynamic range enrichment method of semiconducting single-walled carbon nanotubes with weak field centrifugation

NASA Astrophysics Data System (ADS)

Reis, Wieland G.; Tomović, Željko; Weitz, R. Thomas; Krupke, Ralph; Mikhael, Jules

2017-03-01

The potential of single-walled carbon nanotubes (SWCNTs) to outperform silicon in electronic application was finally enabled through selective separation of semiconducting nanotubes from the as-synthesized statistical mix with polymeric dispersants. Such separation methods provide typically high semiconducting purity samples with narrow diameter distribution, i.e. almost single chiralities. But for a wide range of applications high purity mixtures of small and large diameters are sufficient or even required. Here we proof that weak field centrifugation is a diameter independent method for enrichment of semiconducting nanotubes. We show that the non-selective and strong adsorption of polyarylether dispersants on nanostructured carbon surfaces enables simple separation of diverse raw materials with different SWCNT diameter. In addition and for the first time, we demonstrate that increased temperature enables higher purity separation. Furthermore we show that the mode of action behind this electronic enrichment is strongly connected to both colloidal stability and protonation. By giving simple access to electronically sorted SWCNTs of any diameter, the wide dynamic range of weak field centrifugation can provide economical relevance to SWCNTs.

ATS-6 - UCLA fluxgate magnetometer

NASA Technical Reports Server (NTRS)

Mcpherron, R. L.; Coleman, P. J., Jr.; Snare, R. C.

1975-01-01

A summary of the design of the University of California at Los Angeles' fluxgate magnetometer is presented. Instrument noise in the bandwidth 0.001 to 1.0 Hz is of order 85 m gamma. The DC field of the spacecraft transverse to the earth-pointing axis is 1.0 + or - 21 gamma in the X direction and -2.4 + or - 1.3 gamma in the Y direction. The spacecraft field parallel to this axis is less than 5 gamma. The small spacecraft field has made possible studies of the macroscopic field not previously possible at synchronous orbit. At the 96 W longitude of Applications Technology Satellite-6 (ATS-6), the earth's field is typically inclined 30 deg to the dipole axis at local noon. Most perturbations of the field are due to substorms. These consist of a rotation in the meridian to a more radial field followed by a subsequent rotation back. The rotation back is normally accompanied by transient variations in the azimuthal field. The exact timing of these perturbations is a function of satellite location and the details of substorm development.

High-performance magnetic field sensor based on superconducting quantum interference filters

NASA Astrophysics Data System (ADS)

Caputo, P.; Oppenländer, J.; Häussler, Ch.; Tomes, J.; Friesch, A.; Träuble, T.; Schopohl, N.

2004-08-01

We have developed an absolute magnetic field sensor using a superconducting quantum interference filter (SQIF) made of high-Tc grain-boundary Josephson junctions. The device shows the typical magnetic-field-dependent voltage response V(B ), which is a sharp deltalike dip in the vicinity of zero-magnetic field. When the SQIF is cooled with magnetic shield, and then the shield is removed, the presence of the ambient magnetic field induces a shift of the dip position from B0≈0 to a value B ≈B1, which is about the average value of the Earth's magnetic field, at our latitude. When the SQIF is cooled in the ambient field without shielding, the dip is first found at B ≈B1, and the further shielding of the SQIF results in a shift of the dip towards B0≈0. The low hysteresis observed in the sequence of experiments (less than 5% of B1) makes SQIFs suitable for high precision measurements of the absolute magnetic field. The experimental results are discussed in view of potential applications of high-Tc SQIFs in magnetometry.

Broadband Achromatic Telecentric Lens

NASA Technical Reports Server (NTRS)

Mouroulis, Pantazis

2007-01-01

A new type of lens design features broadband achromatic performance as well as telecentricity, using a minimum number of spherical elements. With appropriate modifications, the lens design form can be tailored to cover the range of response of the focal-plane array, from Si (400-1,000 nm) to InGaAs (400-1,700 or 2,100 nm) or InSb/HgCdTe reaching to 2,500 nm. For reference, lenses typically are achromatized over the visible wavelength range of 480-650 nm. In remote sensing applications, there is a need for broadband achromatic telescopes, normally satisfied with mirror-based systems. However, mirror systems are not always feasible due to size or geometry restrictions. They also require expensive aspheric surfaces. Non-obscured mirror systems can be difficult to align and have a limited (essentially one-dimensional) field of view. Centrally obscured types have a two-dimensional but very limited field in addition to the obscuration. Telecentricity is a highly desirable property for matching typical spectrometer types, as well as for reducing the variation of the angle of incidence and cross-talk on the detector for simple camera types. This rotationally symmetric telescope with no obscuration and using spherical surfaces and selected glass types fills a need in the range of short focal lengths. It can be used as a compact front unit for a matched spectrometer, as an ultra-broadband camera objective lens, or as the optics of an integrated camera/spectrometer in which the wavelength information is obtained by the use of strip or linear variable filters on the focal plane array. This kind of camera and spectrometer system can find applications in remote sensing, as well as in-situ applications for geological mapping and characterization of minerals, ecological studies, and target detection and identification through spectral signatures. Commercially, the lens can be used in quality-control applications via spectral analysis. The lens design is based on the rear landscape lens with the aperture stop in front of all elements. This allows sufficient room for telecentricity in addition to making the stop easily accessible. The crucial design features are the use of a doublet with an ultra-low dispersion glass (fluorite or S-FPL53), and the use of a strong negative element, which enables flat field and telecentricity in conjunction with the last (field lens) element. The field lens also can be designed to be in contact with the array, a feature that is desirable in some applications. The lens has a 20deg field of view, for a 50-mm focal length, and is corrected over the range of wavelengths of 450-2,300 nm. Transverse color, which is the most pernicious aberration for spectroscopic work, is controlled at the level of 1 m or below at 0.7 m field and 5 m at full field. The maximum chief ray angle is less than 1.7 , providing good telecentricity. An additional feature of this lens is that it is made exclusively with glasses that provide good transmission up to 2,300 nm and even some transmission to 2,500 nm; thus, the lens can be used in applications that cover the entire solar-reflected spectrum. Alternative realizations are possible that provide enhanced resolution and even less transverse color over a narrower wavelength range.

Micromechanics thermal stress analysis of composites for space structure applications

NASA Technical Reports Server (NTRS)

Bowles, David E.

1991-01-01

This paper presents results from a finite element micromechanics analysis of thermally induced stresses in composites at cryogenic temperatures typical of spacecraft operating environments. The influence of microstructural geometry, constituent and interphase properties, and laminate orientation were investigated. Stress field results indicated that significant matrix stresses occur in composites exposed to typical spacecraft thermal excursions; these stresses varied with laminate orientation and circumferential position around the fiber. The major difference in the predicted response of unidirectional and multidirectional laminates was the presence of tensile radial stresses, at the fiber/matrix interface, in multidirectional laminates with off-axis ply angles greater than 15 deg. The predicted damage initiation temperatures and modes were in good agreement with experimental data for both low (207 GPa) and high (517 GPa) modulus carbon fiber/epoxy composites.

In Support of a National Treatment Evaluation Study.

PubMed

Brown, Barry S; Flynn, Patrick M

2015-01-01

Argument is made for the importance of conducting a national treatment evaluation to permit understanding of the nature and effectiveness of typical treatment programming. Only through such study can we hope to learn areas of success and failure of normative programming relative to population characteristics and treatment strategies, and the extent to which research-based initiatives have been adopted by the field. That information is central to efforts to draw up a research agenda appropriate to the needs of clients and the staffs responsible for their treatment, and to clarify and respond to gaps in the application of potentially useful treatment components. In spite of such need, our understanding of typical treatment programming and of its effectiveness is based on data collected from a treatment cohort of 20 years ago, although patterns of drug use, characteristics of clients, and the treatment components available have all undergone substantial change. The responsibility taken to provide such information to the field, once seen as a central task of research, needs to be reasserted to strengthen and support our treatment efforts.

Separation of heavy metals: Removal from industrial wastewaters and contaminated soil

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

Peters, R.W.; Shem, L.

1993-01-01

This paper reviews the applicable separation technologies relating to removal of heavy metals from solution and from soils in order to present the state-of-the-art in the field. Each technology is briefly described and typical operating conditions and technology performance are presented. Technologies described include chemical precipitation (including hydroxide, carbonate, or sulfide reagents), coagulation/flocculation, ion exchange, solvent extraction, extraction with chelating agents, complexation, electrochemical operation, cementation, membrane operations, evaporation, adsorption, solidification/stabilization, and vitrification. Several case histories are described, with a focus on waste reduction techniques and remediation of lead-contaminated soils. The paper concludes with a short discussion of important research needsmore » in the field.« less

Separation of heavy metals: Removal from industrial wastewaters and contaminated soil

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

Peters, R.W.; Shem, L.

1993-03-01

This paper reviews the applicable separation technologies relating to removal of heavy metals from solution and from soils in order to present the state-of-the-art in the field. Each technology is briefly described and typical operating conditions and technology performance are presented. Technologies described include chemical precipitation (including hydroxide, carbonate, or sulfide reagents), coagulation/flocculation, ion exchange, solvent extraction, extraction with chelating agents, complexation, electrochemical operation, cementation, membrane operations, evaporation, adsorption, solidification/stabilization, and vitrification. Several case histories are described, with a focus on waste reduction techniques and remediation of lead-contaminated soils. The paper concludes with a short discussion of important research needsmore » in the field.« less

The challenge of sCMOS image sensor technology to EMCCD

NASA Astrophysics Data System (ADS)

Chang, Weijing; Dai, Fang; Na, Qiyue

2018-02-01

In the field of low illumination image sensor, the noise of the latest scientific-grade CMOS image sensor is close to EMCCD, and the industry thinks it has the potential to compete and even replace EMCCD. Therefore we selected several typical sCMOS and EMCCD image sensors and cameras to compare their performance parameters. The results show that the signal-to-noise ratio of sCMOS is close to EMCCD, and the other parameters are superior. But signal-to-noise ratio is very important for low illumination imaging, and the actual imaging results of sCMOS is not ideal. EMCCD is still the first choice in the high-performance application field.

Study of rainfall-induced landslide: a review

NASA Astrophysics Data System (ADS)

Tohari, A.

2018-02-01

Rainfall-induced landslides pose a substantial risk to people and infrastructure. For this reason, there have been numerous studies to understand the landslide mechanism. Most of them were performed on the numerical analysis and laboratory experiment. This paper presents a review of existing research on field hydrological condition of soil slopes leading to the initiation of rainfall-induced landslide. Existing methods to study field hydrological response of slopes are first reviewed, emphasizing their limitations and suitability of application. The typical hydrological response profiles in the slope are then discussed. Subsequently, some significant findings on hydrological condition leading to rainfall-induced landslides are summarized and discussed. Finally, several research topics are recommended for future study.

An Analysis of Once-per-revolution Oscillating Aerodynamic Thrust Loads on Single-Rotation Propellers on Tractor Airplanes at Zero Yaw

NASA Technical Reports Server (NTRS)

Rogallo, Vernon L; Yaggy, Paul F; Mccloud, John L , III

1956-01-01

A simplified procedure is shown for calculating the once-per-revolution oscillating aerodynamic thrust loads on propellers of tractor airplanes at zero yaw. The only flow field information required for the application of the procedure is a knowledge of the upflow angles at the horizontal center line of the propeller disk. Methods are presented whereby these angles may be computed without recourse to experimental survey of the flow field. The loads computed by the simplified procedure are compared with those computed by a more rigorous method and the procedure is applied to several airplane configurations which are believed typical of current designs. The results are generally satisfactory.

Recent Advances in Liquid Metal Manipulation toward Soft Robotics and Biotechnologies.

PubMed

Yu, Yue; Miyako, Eijiro

2018-04-06

Interest has grown significantly in the field of soft robotics, which seeks to develop machinery capable of duplicating the elastic and rheological properties of typically polymeric or elastomeric biological tissues and organs. As a result of a number of unique properties, gallium-based liquid metals (LMs) are emerging as materials used in the forefront of soft robotics research. Finding methods to enable the sophisticated manipulation of LMs will be essential for further progress in the field. This review provides a critical discussion of the manipulation of LMs and on important biotechnological applications of LMs including microfluidics, healthcare devices, biomaterials, and nanomedicines. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulating and discussion on surface plasmon typical optical properties of patterned periodic metallic nanostructures

NASA Astrophysics Data System (ADS)

Liu, Runhan; Yuan, Ying; Long, Huabao; Peng, Sha; Wei, Dong; Zhang, Xinyu; Wang, Haiwei; Xie, Changsheng

2018-02-01

The intense surface plasmons (SPs) can be generated by patterned metal nano-structure arrays, through coupling incident light onto the functioned metal surface, so as to construct highly constrained surface electromagnetic modes. Therefore, a localized micro-nano-field array with a highly compressed surface electron distribution, can also be shaped and even nano-focused over the surface, which will lead to a lot of special physical effects such as anti-reflection effect, and thus indicate many new potential applications in the field of nano-photonics and -optoelectronics. In this paper, several typical patterned sub-wavelength metal nano-structure arrays were designed according to the process, in which common silicon wafer was employed as the substrate material and aluminum as the metal film with different structural size and arrangement circle. In addition, by adjusting the dielectric constant of metal material appropriately, the power control effect on metallic nanostructure was simulated. The key properties such as the excitation intensity of the surface plasmons were studied by simulating the reflectivity characteristic curves and the electric field distribution of the nanostructure excited by incident infrared beams. It is found that the angle of corners, the arrangement cycle and the metal material properties of the patterned nano-structures can be utilized as key factors to control the excitation intensity of surface plasmons.

Integrable perturbed magnetic fields in toroidal geometry: An exact analytical flux surface label for large aspect ratio

NASA Astrophysics Data System (ADS)

Kallinikos, N.; Isliker, H.; Vlahos, L.; Meletlidou, E.

2014-06-01

An analytical description of magnetic islands is presented for the typical case of a single perturbation mode introduced to tokamak plasma equilibrium in the large aspect ratio approximation. Following the Hamiltonian structure directly in terms of toroidal coordinates, the well known integrability of this system is exploited, laying out a precise and practical way for determining the island topology features, as required in various applications, through an analytical and exact flux surface label.

Microchip Capillary Electrophoresis with Electrochemical Detection for Monitoring Environmental Pollutants

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

Chen, Gang; Lin, Yuehe; Wang, Joseph

2006-01-15

This invited paper reviews recent advances and the key strategies in microchip capillary electrophoresis (CE) with electrochemical detection (ECD) for separating and detecting a variety of environmental pollutants. The subjects covered include the fabrication of microfluidic chips, sample pretreatments, ECD, typical applications of microchip CE with ECD in environmental analysis, and future prospects. It is expected that microchip CE-ECD will become a powerful tool in the environmental field and will lead to the creation of truly portable devices.

Field and Laboratory Application of a Gas Chromatograph Low Thermal Mass Resistively Heated Column System in Detecting Traditional and Non-Traditional Chemical Warfare Agents Using Solid Phase Micro-Extraction

DTIC Science & Technology

2005-02-01

followed by extensive sample preparation procedures that are performed in a laboratory. Analysis is typically conducted by injecting a liquid or gas sample...Alfentanil, Remifentanil , Sufentanil, and Carfentanil) in a laboratory. (5) Quantitatively determine a maximum temperature ramping rate at which the LTM...RHT Column combined with a GC-MS can separate and analyze a mixture of non- traditional CWAs (i.e. Fentanyl, Alfentanil, Remifentanil , Sufentanil

Development of mathematical techniques for the assimilation of remote sensing data into atmospheric models

NASA Technical Reports Server (NTRS)

Seinfeld, J. H. (Principal Investigator)

1982-01-01

The problem of the assimilation of remote sensing data into mathematical models of atmospheric pollutant species was investigated. The data assimilation problem is posed in terms of the matching of spatially integrated species burden measurements to the predicted three-dimensional concentration fields from atmospheric diffusion models. General conditions were derived for the reconstructability of atmospheric concentration distributions from data typical of remote sensing applications, and a computational algorithm (filter) for the processing of remote sensing data was developed.

Development of mathematical techniques for the assimilation of remote sensing data into atmospheric models

NASA Technical Reports Server (NTRS)

Seinfeld, J. H. (Principal Investigator)

1982-01-01

The problem of the assimilation of remote sensing data into mathematical models of atmospheric pollutant species was investigated. The problem is posed in terms of the matching of spatially integrated species burden measurements to the predicted three dimensional concentration fields from atmospheric diffusion models. General conditions are derived for the "reconstructability' of atmospheric concentration distributions from data typical of remote sensing applications, and a computational algorithm (filter) for the processing of remote sensing data is developed.

Integrable perturbed magnetic fields in toroidal geometry: An exact analytical flux surface label for large aspect ratio

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

Kallinikos, N.; Isliker, H.; Vlahos, L.

2014-06-15

An analytical description of magnetic islands is presented for the typical case of a single perturbation mode introduced to tokamak plasma equilibrium in the large aspect ratio approximation. Following the Hamiltonian structure directly in terms of toroidal coordinates, the well known integrability of this system is exploited, laying out a precise and practical way for determining the island topology features, as required in various applications, through an analytical and exact flux surface label.

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

Buechler, Elizabeth D.; Pallin, Simon B.; Boudreaux, Philip R.

The indoor air temperature and relative humidity in residential buildings significantly affect material moisture durability, HVAC system performance, and occupant comfort. Therefore, indoor climate data is generally required to define boundary conditions in numerical models that evaluate envelope durability and equipment performance. However, indoor climate data obtained from field studies is influenced by weather, occupant behavior and internal loads, and is generally unrepresentative of the residential building stock. Likewise, whole-building simulation models typically neglect stochastic variables and yield deterministic results that are applicable to only a single home in a specific climate. The

Bialgebra deformations and algebras of trees

NASA Technical Reports Server (NTRS)

Grossman, Robert; Radford, David

1991-01-01

Let A denote a bialgebra over a field k and let A sub t = A((t)) denote the ring of formal power series with coefficients in A. Assume that A is also isomorphic to a free, associative algebra over k. A simple construction is given which makes A sub t a bialgebra deformation of A. In typical applications, A sub t is neither commutative nor cocommutative. In the terminology of Drinfeld, (1987), A sub t is a quantum group. This construction yields quantum groups associated with families of trees.

Projection lenses for high-resolution ablation with excimer lasers: high-performance, wide-field and high-UV laser power

NASA Astrophysics Data System (ADS)

Schlichting, Johannes; Winkler, Kerstin; Koerner, Lienhard; Schletterer, Thomas; Burghardt, Berthold; Kahlert, Hans-Juergen

2000-10-01

The productive and accurate ablation of microstructures demands the precise imaging of a mask pattern onto the substrate under work. The job can be done with high performance wide field lenses as a key component of ablation equipment. The image field has dimensions of 20 to 30 mm. Typical dimensions and accuracy of the microstructures are in the order of some microns. On the other hand, the working depth of focus (DOF) has to be in the order of some 10 microns to be successful on drilling through 20 to 50 μm substrates. All these features have to be reached under the conditions of high power laser UV light. Some design principles for such systems are applied, such as optimum number of elements, minimum tolerance sensitivity, material restrictions for the lens elements as well as mechanical parts (mounting), restrictions of possible power densities on lens surfaces (including ghosts), matched quality for the manufactures system. The special applications require appropriate performance criteria for theoretical calculation and measurements, which allow to conclude the performance of the application. The base is wave front calculation and measurement (using Shack- Hartmann sensor) in UV. Derived criteria are calculated and compared with application results.

Development of micronic GMR-magnetoresistive sensors for non-destructive sensing applications (Presentation Recording)

NASA Astrophysics Data System (ADS)

Jaffrès, Henri; LeMaitre, Yves; Collin, Sophie; Nguyen Vandau, Frédéric; Sergeeva-Chollet, Natalia; Decitre, Jean-Marc

2015-09-01

We will present our last development of GMR-based magnetic sensors devoted to sensing application for non-destructive control application. In these first realizations, we have chosen a so-called shape anisotropy - exchange biased strategy to fulfill the field-sensing criteria in the μT range in devices made of micronic single elements. Our devices realized by optical lithography, and whose typical sizes range from 150 μm x 150 μm to 500 μm x 500 μm elements, are made of trilayers GMR-based technology and consist of several circuitries of GMR elements of different lengths, widths and gaps. To obtain a full sensing linearity and reversibility requiring a perpendicular magnetic arrangement between both sensitive and hard layer, the magnetization of the latter have been hardened by pinning it with an antiferromagnetic material. The specific geometry of the design have been engineered in order to optimize the magnetic response of the soft layer via the different magnetic torques exerted on it essentially played by the dipolar fields or shape anisotropy, and the external magnetic field to detect. The smaller dimensions in width and in gap are then respectively of 2 μm and 3 μm to benefit of the full shape anisotropy formatting the magnetic response.

Cyclododecane exposure in the field of conservation and restoration of art objects.

PubMed

Vernez, David; Wognin, Barthélémy; Tomicic, Catherine; Plateel, Gregory; Charrière, Nicole; Bruhin, Stefanie

2011-04-01

Recent work practices in the conservation and restoration involve the use of cyclododecane (CDD, CAS 294-62-2) to protect fragile artifacts during their handling or transportation. Little is known about its toxicity, and no previous exposure has been reported. A short field investigation was conducted to characterize the exposure conditions to both CDD vapors and aerosols. Measurements were conducted in the laboratory of conservation and restoration of the archeological service in Bern (Switzerland). Three indoor and four outdoor typical work situations, either during brush or spray gun applications, were investigated. Measurements were performed on charcoal adsorbent tube and analyzed by a gas chromatograph equipped with a flame ionization detector. Measurements have been conducted during both brush and spray gun applications. Indoor exposures were of 0.75-15.5 mg/m(3), while outdoors exposures were 19.5-53.9 mg/m(3). Exposures appear to be extremely localized due to both physicochemical properties and application methods of the CDD. Vapor exposure increases dramatically with the confinement of the workplace. Preventive measures should be undertaken to limit as much as possible these exposures. Field work in confined areas (ditches, underground) is of particular concern. CDD-coated artifacts or materials should be stored in ventilated areas to avoid delayed exposures.

Space charge effects on the current-voltage characteristics of gated field emitter arrays

NASA Astrophysics Data System (ADS)

Jensen, K. L.; Kodis, M. A.; Murphy, R. A.; Zaidman, E. G.

1997-07-01

Microfabricated field emitter arrays (FEAs) can provide the very high electron current densities required for rf amplifier applications, typically on the order of 100 A/cm2. Determining the dependence of emission current on gate voltage is important for the prediction of emitter performance for device applications. Field emitters use high applied fields to extract current, and therefore, unlike thermionic emitters, the current densities can exceed 103A/cm2 when averaged over an array. At such high current densities, space charge effects (i.e., the influence of charge between cathode and collector on emission) affect the emission process or initiate conditions which can lead to failure mechanisms for field emitters. A simple model of a field emitter will be used to calculate the one-dimensional space charge effects on the emission characteristics by examining two components: charge between the gate and anode, which leads to Child's law, and charge within the FEA unit cell, which gives rise to a field suppression effect which can exist for a single field emitter. The predictions of the analytical model are compared with recent experimental measurements designed to assess space charge effects and predict the onset of gate current. It is shown that negative convexity on a Fowler-Nordheim plot of Ianode(Vgate) data can be explained in terms of field depression at the emitter tip in addition to reflection of electrons by a virtual cathode created when the anode field is insufficient to extract all of the current; in particular, the effects present within the unit cell constitute a newly described effect.

[Preliminary application of scripting in RayStation TPS system].

PubMed

Zhang, Jianying; Sun, Jing; Wang, Yun

2013-07-01

Discussing the basic application of scripting in RayStation TPS system. On the RayStation 3.0 Platform, the programming methods and the points should be considered during basic scripting application were explored with the help of utility scripts. The typical planning problems in the field of beam arrangement and plan outputting were used as examples by ironprthon language. The necessary properties and the functions of patient object for script writing can be extracted from RayStation system. With the help of NET controls, planning functions such as the interactive parameter input, treatment planning control and the extract of the plan have been realized by scripts. With the help of demo scripts, scripts can be developed in RayStation, as well as the system performance can be upgraded.

Enhanced Denitrification in Roadside Ditches with Bioreactors

NASA Astrophysics Data System (ADS)

Pluer, W.; Schneider, R.; Walter, M. T.

2016-12-01

Nitrate (NO3) pollution remains a water quality problem in agriculture-dominated watersheds despite decades of research and concerted efforts. Excess NO3 causes eutrophication in estuarine and marine ecosystems far downstream of the pollution source. Denitrification reduces NO3 to inert dinitrogen gas; this process occurs naturally in saturated areas of the landscape but this rate cannot keep up with the runoff rate due to fertilizer and manure applications. Researchers developed denitrifying bioreactors as a solution to encourage denitrification at the field level. Denitrifying bioreactors remove NO3 at a significantly higher rate (>2 g N m-2 d-1) than natural systems such as wetlands (<0.5 g N m-2 d-1). Most current designs of denitrifying bioreactors necessitate connection with tile drainage as the inflow source of water and NO3. It also requires a portion of farmland (typically <1% of field area is needed) which farmers can be reluctant to relinquish. Meanwhile, road ditches commonly run along agricultural fields, channeling runoff and NO3 to surface water. Because the ditches are designed to avoid flooding, they channel water rapidly and minimize time and contact with soil microbes for denitrification (denitrification rates in ditches are typically <0.1 g N m-2 d-1). Modified denitrifying bioreactors placed in road ditches could provide high NO3 removal in already marginal land, especially at baseflow conditions. A pilot study of this shows instantaneous NO3 removal rates up to 110 g N m-2 d-1 in the first year. Continued results similar to this pilot study and wider application could significantly increase ditch denitrification and help mitigate NO3 pollution.

Magnetic-field-controlled negative differential conductance in scanning tunneling spectroscopy of graphene npn junction resonators

NASA Astrophysics Data System (ADS)

Li, Si-Yu; Liu, Haiwen; Qiao, Jia-Bin; Jiang, Hua; He, Lin

2018-03-01

Negative differential conductance (NDC), characterized by the decreasing current with increasing voltage, has attracted continuous attention for its various novel applications. The NDC typically exists in a certain range of bias voltages for a selected system and controlling the regions of NDC in curves of current versus voltage (I -V ) is experimentally challenging. Here, we demonstrate a magnetic-field-controlled NDC in scanning tunneling spectroscopy of graphene npn junction resonators. The magnetic field not only can switch on and off the NDC, but also can continuously tune the regions of the NDC in the I -V curves. In the graphene npn junction resonators, magnetic fields generate sharp and pronounced Landau-level peaks with the help of the Klein tunneling of massless Dirac fermions. A tip of scanning tunneling microscope induces a relatively shift of the Landau levels in graphene beneath the tip. Tunneling between the misaligned Landau levels results in the magnetic-field-controlled NDC.

Study of magnetic resonance with parametric modulation in a potassium vapor cell

NASA Astrophysics Data System (ADS)

Zhang, Rui; Wang, Zhiguo; Peng, Xiang; Li, Wenhao; Li, Songjian; Guo, Hong; Cream Team

2017-04-01

A typical magnetic-resonance scheme employs a static bias magnetic field and an orthogonal driving magnetic field oscillating at the Larmor frequency, at which the atomic polarization precesses around the static magnetic field. We demonstrate in a potassium vapor cell the variations of the resonance condition and the spin precession dynamics resulting from the parametric modulation of the bias field, which are in well agreement with theoretical predictions from the Bloch equation. We show that, the driving magnetic field with the frequency detuned by different harmonics of the parametric modulation frequency can lead to resonance as well. Also, a series of frequency sidebands centered at the driving frequency and spaced by the parametric modulation frequency can be observed in the precession of the atomic polarization. These effects could be used in different atomic magnetometry applications. This work is supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 61225003) and the National Natural Science Foundation of China (Grant Nos. 61531003 and 61571018).

A high-resolution full-field range imaging system

NASA Astrophysics Data System (ADS)

Carnegie, D. A.; Cree, M. J.; Dorrington, A. A.

2005-08-01

There exist a number of applications where the range to all objects in a field of view needs to be obtained. Specific examples include obstacle avoidance for autonomous mobile robots, process automation in assembly factories, surface profiling for shape analysis, and surveying. Ranging systems can be typically characterized as being either laser scanning systems where a laser point is sequentially scanned over a scene or a full-field acquisition where the range to every point in the image is simultaneously obtained. The former offers advantages in terms of range resolution, while the latter tend to be faster and involve no moving parts. We present a system for determining the range to any object within a camera's field of view, at the speed of a full-field system and the range resolution of some point laser scans. Initial results obtained have a centimeter range resolution for a 10 second acquisition time. Modifications to the existing system are discussed that should provide faster results with submillimeter resolution.

Plasma rotation by electric and magnetic fields in a discharge cylinder

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.; Hong, S. H.

1977-01-01

A theoretical model for an electric discharge consisting of a spatially diverging plasma sustained electrically between a small ring cathode and a larger ring anode in a cylindrical chamber with an axial magnetic field is developed to study the rotation of the discharge plasma in the crossed electric and magnetic fields. The associated boundary-value problem for the coupled partial differential equations which describe the electric potential and the plasma velocity fields is solved in closed form. The electric field, current density, and velocity distributions are discussed in terms of the Hartmann number and the Hall coefficient. As a result of Lorentz forces, the plasma rotates with speeds as high as 1 million cm/sec around its axis of symmetry at typical conditions. As an application, it is noted that rotating discharges of this type could be used to develop a high-density plasma-ultracentrifuge driven by j x B forces, in which the lighter (heavier) ion and atom components would be enriched in (off) the center of the discharge cylinder.

Confinement-induced InAs/GaSb heterojunction electron-hole bilayer tunneling field-effect transistor

NASA Astrophysics Data System (ADS)

Padilla, J. L.; Medina-Bailon, C.; Alper, C.; Gamiz, F.; Ionescu, A. M.

2018-04-01

Electron-Hole Bilayer Tunneling Field-Effect Transistors are typically based on band-to-band tunneling processes between two layers of opposite charge carriers where tunneling directions and gate-induced electric fields are mostly aligned (so-called line tunneling). However, the presence of intense electric fields associated with the band bending required to trigger interband tunneling, along with strong confinement effects, has made these types of devices to be regarded as theoretically appealing but technologically impracticable. In this work, we propose an InAs/GaSb heterostructure configuration that, although challenging in terms of process flow design and fabrication, could be envisaged for alleviating the electric fields inside the channel, whereas, at the same time, making quantum confinement become the mechanism that closes the broken gap allowing the device to switch between OFF and ON states. The utilization of induced doping prevents the harmful effect of band tails on the device performance. Simulation results lead to extremely steep slope characteristics endorsing its potential interest for ultralow power applications.

A rapid boundary integral equation technique for protein electrostatics

NASA Astrophysics Data System (ADS)

Grandison, Scott; Penfold, Robert; Vanden-Broeck, Jean-Marc

2007-06-01

A new boundary integral formulation is proposed for the solution of electrostatic field problems involving piecewise uniform dielectric continua. Direct Coulomb contributions to the total potential are treated exactly and Green's theorem is applied only to the residual reaction field generated by surface polarisation charge induced at dielectric boundaries. The implementation shows significantly improved numerical stability over alternative schemes involving the total field or its surface normal derivatives. Although strictly respecting the electrostatic boundary conditions, the partitioned scheme does introduce a jump artefact at the interface. Comparison against analytic results in canonical geometries, however, demonstrates that simple interpolation near the boundary is a cheap and effective way to circumvent this characteristic in typical applications. The new scheme is tested in a naive model to successfully predict the ground state orientation of biomolecular aggregates comprising the soybean storage protein, glycinin.

A Portable FTIR Analyser for Field Measurements of Trace Gases and their Isotopologues: CO2, CH4, N2O, CO, del13C in CO2 and delD in water vapour

NASA Astrophysics Data System (ADS)

Griffith, D. W.; Bryant, G. R.; Deutscher, N. M.; Wilson, S. R.; Kettlewell, G.; Riggenbach, M.

2007-12-01

We describe a portable Fourier Transform InfraRed (FTIR) analyser capable of simultaneous high precision analysis of CO2, CH4, N2O and CO in air, as well as δ13C in CO2 and δD in water vapour. The instrument is based on a commercial 1 cm-1 resolution FTIR spectrometer fitted with a mid-IR globar source, 26 m multipass White cell and thermoelectrically-cooled MCT detector operating between 2000 and 7500 cm-1. Air is passed through the cell and analysed in real time without any pre-treatment except for (optional) drying. An inlet selection manifold allows automated sequential analysis of samples from one or more inlet lines, with typical measurement times of 1-10 minutes per sample. The spectrometer, inlet sampling sequence, real-time quantitative spectrum analysis, data logging and display are all under the control of a single program running on a laptop PC, and can be left unattended for continuous measurements over periods of weeks to months. Selected spectral regions of typically 100-200 cm-1 width are analysed by a least squares fitting technique to retrieve concentrations of trace gases, 13CO2 and HDO. Typical precision is better than 0.1% without the need for calibration gases. Accuracy is similar if measurements are referenced to calibration standard gases. δ13C precision is typically around 0.1‰, and for δD it is 1‰. Applications of the analyser include clean and polluted air monitoring, tower-based flux measurements such as flux gradient or integrated horizontal flux measurements, automated soil chambers, and field-based measurements of isotopic fractionation in soil-plant-atmosphere systems. The simultaneous multi-component advantages can be exploited in tracer-type emission measurements, for example of CH4 from livestock using a co-released tracer gas and downwind measurement. We have also developed an open path variant especially suited to tracer release studies and measurements of NH3 emissions from agricultural sources. An illustrative selection of applications will be presented.

Microgravity Fluid Management Symposium

NASA Technical Reports Server (NTRS)

1987-01-01

The NASA Microgravity Fluid Management Symposium, held at the NASA Lewis Research Center, September 9 to 10, 1986, focused on future research in the microgravity fluid management field. The symposium allowed researchers and managers to review space applications that require fluid management technology, to present the current status of technology development, and to identify the technology developments required for future missions. The 19 papers covered three major categories: (1) fluid storage, acquisition, and transfer; (2) fluid management applications, i.e., space power and thermal management systems, and environmental control and life support systems; (3) project activities and insights including two descriptions of previous flight experiments and a summary of typical activities required during development of a shuttle flight experiment.

Flow visualization of discrete hole film cooling for gas turbine applications

NASA Technical Reports Server (NTRS)

Colladay, R. S.; Russell, L. M.

1975-01-01

Film injection from discrete holes in a three row staggered array with 5-diameter spacing is studied. The boundary layer thickness-to-hole diameter ratio and Reynolds number are typical of gas turbine film cooling applications. Two different injection locations are studied to evaluate the effect of boundary layer thickness on film penetration and mixing. Detailed streaklines showing the turbulent motion of the injected air are obtained by photographing neutrally buoyant helium filled soap bubbles which follow the flow field. The bubble streaklines passing downstream injection locations are clearly identifiable and can be traced back to their origin. Visualization of surface temperature patterns obtained from infrared photographs of a similar film cooled surface are also included.

Application of MOS-1 MESSR image to the investigation of wetlands in Poyang Lake

NASA Astrophysics Data System (ADS)

Chen, Shuisen; Li, Yan

1998-08-01

The lake beach and grass moor land is a kind of typical wetlands. The area varies greatly with season in Poyang Lake region. Moreover, the field investigation of wetlands is almost impossible as geographical features and difficulties in transportation. The notes address the potential role of remote sensing in the surveying of the lake beach and grass moor land. In particular, the notes reflect the characteristics relationships between MOS-1 MESSR image and the wetlands. The application results show that MOS-1 MESSR image is effective in surveying the wetland area variation and distribution (lake, river, grass moor, mud flat, sand beach, etc.). detecting lake base shape, and analyzing eco-environment surrounded.

Terahertz Scattering

NASA Astrophysics Data System (ADS)

Zurk, L. M.; Schecklman, S.

Terahertz (THz) Time Domain Spectroscopy (TDS) measurements have the unique ability to detect both the amplitude and phase of the electric field, simultaneously. This eliminates complications introduced by Kramers-Kronig relations typically used in near-infrared spectroscopy. Many materials of interest contain resonant features in their refractive indices in the far-infrared (THz) spectrum, while their packaging materials are generally transparent. Thus, an important application for THz TDS is the ability to see inside packaging materials and detect the material features of their contents. Such applications are promising for security screening (concealed drugs, explosives, etc.) in post offices and airports as well as for non-destructive evaluation (NDE) of products on an assembly line or tissue damage due to burns or cancer [1-6].

Electric Field Simulation of Surge Capacitors with Typical Defects

NASA Astrophysics Data System (ADS)

Zhang, Chenmeng; Mao, Yuxiang; Xie, Shijun; Zhang, Yu

2018-03-01

The electric field of power capacitors with different typical defects in DC working condition and impulse oscillation working condition is studied in this paper. According to the type and location of defects and considering the influence of space charge, two-dimensional models of surge capacitors with different typical defects are simulated based on ANSYS. The distribution of the electric field inside the capacitor is analyzed, and the concentration of electric field and its influence on the insulation performance are obtained. The results show that the type of defects, the location of defects and the space charge all affect the electric field distribution inside the capacitor in varying degrees. Especially the electric field distortion in the local area such as sharp corners and burrs is relatively larger, which increases the probability of partial discharge inside the surge capacitor.

Clinical application of adipose stem cells in plastic surgery.

PubMed

Kim, Yong-Jin; Jeong, Jae-Ho

2014-04-01

Adipose stem cells (ASCs) are a type of adult stem cells that share common characteristics with typical mesenchymal stem cells. In the last decade, ASCs have been shown to be a useful cell resource for tissue regeneration. The major role of regenerative medicine in this century is based on cell therapy in which ASCs hold a key position. Active research on this new type of adult stem cell has been ongoing and these cells now have several clinical applications, including fat grafting, overcoming wound healing difficulties, recovery from local tissue ischemia, and scar remodeling. The application of cultured cells will increase the efficiency of cell therapy. However, the use of cultured stem cells is strictly controlled by government regulation to ensure patient safety. Government regulation is a factor that can limit more versatile clinical application of ASCs. In this review, current clinical applications of ASCs in plastic surgery are introduced. Future stem cell applications in clinical field including culturing and banking of ASCs are also discussed in this review.

Clothianidin in agricultural soils and uptake into corn pollen and canola nectar after multiyear seed treatment applications

PubMed Central

Dyer, Dan G.; McConnell, Laura L.; Bondarenko, Svetlana; Allen, Richard; Heinemann, Oliver

2016-01-01

Abstract Limited data are available on the fate of clothianidin under realistic agricultural production conditions. The present study is the first large‐scale assessment of clothianidin residues in soil and bee‐relevant matrices from corn and canola fields after multiple years of seed‐treatment use. The average soil concentration from 50 Midwest US corn fields with 2 yr to 11 yr of planting clothianidin‐treated seeds was 7.0 ng/g, similar to predicted concentrations from a single planting of Poncho 250‐treated corn seeds (6.3 ng/g). The water‐extractable (i.e., plant‐bioavailable) clothianidin residues in soil were only 10% of total residues. Clothianidin concentrations in soil reached a plateau concentration (amount applied equals amount dissipated) in fields with 4 or more application years. Concentrations in corn pollen from these fields were low (mean: 1.8 ng/g) with no correlation to total years of use or soil concentrations. For canola, soil concentrations from 27 Canadian fields with 2 yr to 4 yr of seed treatment use (mean = 5.7 ng/g) were not correlated with use history, and plant bioavailability was 6% of clothianidin soil residues. Average canola nectar concentrations were 0.6 ng/g and not correlated to use history or soil concentrations. Under typical cropping practices, therefore, clothianidin residues are not accumulating significantly in soil, plant bioavailability of residues in soil is limited, and exposure to pollinators will not increase over time in fields receiving multiple applications of clothianidin. Environ Toxicol Chem 2016;35:311–321. © 2015 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC. PMID:26467536

Electron-Beam Diagnostic Methods for Hypersonic Flow Diagnostics

NASA Technical Reports Server (NTRS)

1994-01-01

The purpose of this work was the evaluation of the use of electron-bean fluorescence for flow measurements during hypersonic flight. Both analytical and numerical models were developed in this investigation to evaluate quantitatively flow field imaging concepts based upon the electron beam fluorescence technique for use in flight research and wind tunnel applications. Specific models were developed for: (1) fluorescence excitation/emission for nitrogen, (2) rotational fluorescence spectrum for nitrogen, (3) single and multiple scattering of electrons in a variable density medium, (4) spatial and spectral distribution of fluorescence, (5) measurement of rotational temperature and density, (6) optical filter design for fluorescence imaging, and (7) temperature accuracy and signal acquisition time requirements. Application of these models to a typical hypersonic wind tunnel flow is presented. In particular, the capability of simulating the fluorescence resulting from electron impact ionization in a variable density nitrogen or air flow provides the capability to evaluate the design of imaging instruments for flow field mapping. The result of this analysis is a recommendation that quantitative measurements of hypersonic flow fields using electron-bean fluorescence is a tractable method with electron beam energies of 100 keV. With lower electron energies, electron scattering increases with significant beam divergence which makes quantitative imaging difficult. The potential application of the analytical and numerical models developed in this work is in the design of a flow field imaging instrument for use in hypersonic wind tunnels or onboard a flight research vehicle.

Application of time-division-multiplexed lasers for measurements of gas temperature and CH4 and H2O concentrations at 30 kHz in a high-pressure combustor.

PubMed

Caswell, Andrew W; Kraetschmer, Thilo; Rein, Keith; Sanders, Scott T; Roy, Sukesh; Shouse, Dale T; Gord, James R

2010-09-10

Two time-division-multiplexed (TDM) sources based on fiber Bragg gratings were applied to monitor gas temperature, H(2)O mole fraction, and CH(4) mole fraction using line-of-sight absorption spectroscopy in a practical high-pressure gas turbine combustor test article. Collectively, the two sources cycle through 14 wavelengths in the 1329-1667 nm range every 33 μs. Although it is based on absorption spectroscopy, this sensing technology is fundamentally different from typical diode-laser-based absorption sensors and has many advantages. Specifically, the TDM lasers allow efficient, flexible acquisition of discrete-wavelength information over a wide spectral range at very high speeds (typically 30 kHz) and thereby provide a multiplicity of precise data at high speeds. For the present gas turbine application, the TDM source wavelengths were chosen using simulated temperature-difference spectra. This approach is used to select TDM wavelengths that are near the optimum values for precise temperature and species-concentration measurements. The application of TDM lasers for other measurements in high-pressure, turbulent reacting flows and for two-dimensional tomographic reconstruction of the temperature and species-concentration fields is also forecast.

Biosolids applied to agricultural land: Influence on structural and functional endpoints of soil fauna on a short- and long-term scale.

PubMed

Coors, Anja; Edwards, Mark; Lorenz, Pascale; Römbke, Jörg; Schmelz, Rüdiger M; Topp, Edward; Waszak, Karolina; Wilkes, Graham; Lapen, David R

2016-08-15

Biosolids have well-documented crop and soil benefits similar to other sources of organic amendment, but there is environmental concern due to biosolids-associated pollutants. The present study investigated two field sites that had received biosolids at commercial-scale rates in parallel to associated field sections which were managed similarly but without receiving biosolids (controls). The investigated endpoints were abundance and diversity of soil organisms (nematodes, enchytraeids and earthworms) and soil fauna feeding activity as measured by the bait lamina assay. Repeated sampling of one of the field sites following the only biosolids application demonstrated an enrichment effect typical for organic amendments, which was mostly exhausted after 44months. After an initial suppression, the proportion of free-living plant-parasitic nematodes tended to increase in the biosolids-amended soil over time. Yet, none of the endpoints at this site indicated significant negative effects resulting from the biosolids until 44months post application. In contrast to the repeatedly tilled first field site, the second one was left fallow after three biosolids applications, and was sampled 96months post last application. It was only at this field site that potential evidence for a long-term impact of biosolids was detected with regard to two endpoints: earthworm abundance and structure of the nematode assemblage. Agricultural management and correlation with abiotic soil parameters explained the observed difference in earthworm abundance. Yet, the development of a highly structured and mature nematode assemblage at the control but not at the biosolids-amended section of this fallow field could not be explained by such correlations nor by soil metal concentrations. Overall, the present study found only weak evidence for negative long-term impacts of biosolids applied at commercial rates on soil fauna. High-level community parameters such as the nematode structure index (SI) appeared more suitable to detect deleterious effects on soil fauna than simple abundance measurements. Copyright © 2016 Elsevier B.V. All rights reserved.

Rainfall-runoff of anthropogenic waste indicators from agricultural fields applied with municipal biosolids.

PubMed

Gray, James L; Borch, Thomas; Furlong, Edward T; Davis, Jessica G; Yager, Tracy J; Yang, Yun-Ya; Kolpin, Dana W

2017-02-15

The presence of anthropogenic contaminants such as antimicrobials, flame-retardants, and plasticizers in runoff from agricultural fields applied with municipal biosolids may pose a potential threat to the environment. This study assesses the potential for rainfall-induced runoff of 69 anthropogenic waste indicators (AWIs), widely found in household and industrial products, from biosolids amended field plots. The agricultural field containing the test plots was treated with biosolids for the first time immediately prior to this study. AWIs present in soil and biosolids were isolated by continuous liquid-liquid extraction and analyzed by full-scan gas chromatography/mass spectrometry. Results for 18 AWIs were not evaluated due to their presence in field blank QC samples, and another 34 did not have sufficient detection frequency in samples to analyze trends in data. A total of 17 AWIs, including 4-nonylphenol, triclosan, and tris(2-butoxyethyl)phosphate, were present in runoff with acceptable data quality and frequency for subsequent interpretation. Runoff samples were collected 5days prior to and 1, 9, and 35days after biosolids application. Of the 17 AWIs considered, 14 were not detected in pre-application samples, or their concentrations were much smaller than in the sample collected one day after application. A range of trends was observed for individual AWI concentrations (typically from 0.1 to 10μg/L) over the course of the study, depending on the combination of partitioning and degradation mechanisms affecting each compound most strongly. Overall, these results indicate that rainfall can mobilize anthropogenic contaminants from biosolids-amended agricultural fields, directly to surface waters and redistribute them to terrestrial sites away from the point of application via runoff. For 14 of 17 compounds examined, the potential for runoff remobilization during rainstorms persists even after three 100-year rainstorm-equivalent simulations and the passage of a month. Copyright © 2016. Published by Elsevier B.V.

Rainfall-runoff of anthropogenic waste indicators from agricultural fields applied with municipal biosolids

USGS Publications Warehouse

Gray, James L.; Borch, Thomas; Furlong, Edward T.; Davis, Jessica; Yager, Tracy; Yang, Yun-Ya; Kolpin, Dana W.

2017-01-01

The presence of anthropogenic contaminants such as antimicrobials, flame-retardants, and plasticizers in runoff from agricultural fields applied with municipal biosolids may pose a potential threat to the environment. This study assesses the potential for rainfall-induced runoff of 69 anthropogenic waste indicators (AWIs), widely found in household and industrial products, from biosolids amended field plots. The agricultural field containing the test plots was treated with biosolids for the first time immediately prior to this study. AWIs present in soil and biosolids were isolated by continuous liquid-liquid extraction and analyzed by full-scan gas chromatography/mass spectrometry. Results for 18 AWIs were not evaluated due to their presence in field blank QC samples, and another 34 did not have sufficient detection frequency in samples to analyze trends in data. A total of 17 AWIs, including 4-nonylphenol, triclosan, and tris(2-butoxyethyl)phosphate, were present in runoff with acceptable data quality and frequency for subsequent interpretation. Runoff samples were collected 5 days prior to and 1, 9, and 35 days after biosolids application. Of the 17 AWIs considered, 14 were not detected in pre-application samples, or their concentrations were much smaller than in the sample collected one day after application. A range of trends was observed for individual AWI concentrations (typically from 0.1 to 10 μg/L) over the course of the study, depending on the combination of partitioning and degradation mechanisms affecting each compound most strongly. Overall, these results indicate that rainfall can mobilize anthropogenic contaminants from biosolids-amended agricultural fields, directly to surface waters and redistribute them to terrestrial sites away from the point of application via runoff. For 14 of 17 compounds examined, the potential for runoff remobilization during rainstorms persists even after three 100-year rainstorm-equivalent simulations and the passage of a month.

Sediment environment of Port Valdez, Alaska: the effect of oil on this ecosystem

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

Feder, H.M.; Cheek, M.; Flanagan, P.

1976-07-01

The Port Valdez intertidal sediment system was studied for three years. Physical, geological, geochemical, hydrocarbon, and biological features were examined. Sediments were poorly sorted gravels to plastic clays, and had low amounts of organic matter. Bacterial numbers varied from site to site, and decreased in numbers with depth. Meiofauna consisted primarily of nematodes and harpacticoid copepods. Most meiofaunal species were restricted to the upper three centimeters throughout the year. Meiofaunal densities wre typically highest in summer and lowest in winter. Reproductive activities of copepods tended to be seasonal with only one species reproducing throughout the year. Bacterial populations were unaffectedmore » by single applications. It is concluded that oil is removed rapidly by tidal action. Three species of copepods exposed to oil in the field significantly increased in density in experimentally oiled plots. Uptake and release of added oil by intertidal sediments and the clam (Macoma balthica) were examined in the field. Petroleum was not detectable two months after application to sediments.« less

High-efficient light absorption of monolayer graphene via cylindrical dielectric arrays and the sensing application

NASA Astrophysics Data System (ADS)

Zhou, Peng; Zheng, Gaige

2018-04-01

The efficiency of graphene-based optoelectronic devices is typically limited by the poor absolute absorption of light. A hybrid structure of monolayer graphene with cylindrical titanium dioxide (TiO2) array and aluminum oxide (Al2O3) spacer layer on aluminum (Al) substrate has been proposed to enhance the absorption for two-dimensional (2D) materials. By combining dielectric array with metal substrate, the structure achieves multiple absorption peaks with near unity absorbance at near-infrared wavelengths due to the resonant effect of dielectric array. Completed monolayer graphene is utilized in the design without any demand of manufacture process to form the periodic patterns. Further analysis indicates that the near-field enhancement induced by surface modes gives rise to the high absorption. This favorable field enhancement and tunability of absorption not only open up new approaches to accelerate the light-graphene interaction, but also show great potential for practical applications in high-performance optoelectronic devices, such as modulators and sensors.

The ReaxFF reactive force-field: Development, applications, and future directions

DOE PAGES

Senftle, Thomas; Hong, Sungwook; Islam, Md Mahbubul; ...

2016-03-04

The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFFmore » method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. As a result, this article provides an overview of the development, application, and future directions of the ReaxFF method.« less

Particle flow within a transonic compressor rotor passage with application to laser-Doppler velocimetry

NASA Technical Reports Server (NTRS)

Maxwell, B. R.

1975-01-01

A theoretical analysis was conducted of the dynamic behavior of micron size particles moving in the three-dimensional flow field of a rotating transonic axial-flow air compressor rotor. The particle velocity lag and angular deviation relative to the gas were determined as functions of particle diameter, mass density and radial position. Particle size and density were varied over ranges selected to correspond to typical laser-Doppler velocimeter (LDV) flow field mapping applications. It was found that the particles move essentially on gas stream surfaces and that particle tracking is relatively insensitive to the rotor radial coordinate. Velocity lag and angular deviation increased whenever particle size or mass density increased, and particle tracking was more sensitive to a change in particle diameter than to a corresponding change in mass density. Results indicated that velocity and angular deviations generally less than 1 percent and 1 degree could be achieved with 1 gm/cc tracer particles with diameters of 1 micron or less.

Pesticides and their effects on wildlife

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

Driver, C.J.

1994-07-01

About 560 active ingredients are currently used as pesticides. Applications of these pesticides are made to agricultural lands and other areas inhabited by wildlife. Unfortunately, many agricultural-use pesticides also entail some measure of risk to organisms other than the pest species. Because testing of pesticides prior to registration cannot evaluate all the potential environmental-pesticide-wildlife/fish interactions, current methods of risk assessment do not always provide sufficient safety to nontarget organisms. This is evidenced by die-offs of fish and wildlife from applications of pesticides at environmentally {open_quotes}safe{close_quotes} rates, the linking of population declines of some species with agrochemical use, and observations ofmore » survival-threatening behavioral changes in laboratory and field animals exposed to typical field levels of pesticides. It is important to note, however, that the majority of pesticides, when properly applied, have not caused significant injury to wildlife. A brief summary of pesticide effects on wildlife and fish are presented for the common classes of pesticides in use today.« less

Tackling the challenges of fully immersive head-mounted AR devices

NASA Astrophysics Data System (ADS)

Singer, Wolfgang; Hillenbrand, Matthias; Münz, Holger

2017-11-01

The optical requirements of fully immersive head mounted AR devices are inherently determined by the human visual system. The etendue of the visual system is large. As a consequence, the requirements for fully immersive head-mounted AR devices exceeds almost any high end optical system. Two promising solutions to achieve the large etendue and their challenges are discussed. Head-mounted augmented reality devices have been developed for decades - mostly for application within aircrafts and in combination with a heavy and bulky helmet. The established head-up displays for applications within automotive vehicles typically utilize similar techniques. Recently, there is the vision of eyeglasses with included augmentation, offering a large field of view, and being unobtrusively all-day wearable. There seems to be no simple solution to reach the functional performance requirements. Known technical solutions paths seem to be a dead-end, and some seem to offer promising perspectives, however with severe limitations. As an alternative, unobtrusively all-day wearable devices with a significantly smaller field of view are already possible.

Retrieving Storm Electric Fields From Aircraft Field Mill Data. Part 2; Applications

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Mach, D. M.; Christian, H. J.; Stewart, M. F.; Bateman, M. G.

2005-01-01

The Lagrange multiplier theory and "pitch down method" developed in Part I of this study are applied to complete the calibration of a Citation aircraft that is instrumented with six field mill sensors. When side constraints related to average fields are used, the method performs well in computer simulations. For mill measurement errors of 1 V/m and a 5 V/m error in the mean fair weather field function, the 3-D storm electric field is retrieved to within an error of about 12%. A side constraint that involves estimating the detailed structure of the fair weather field was also tested using computer simulations. For mill measurement errors of 1 V/m, the method retrieves the 3-D storm field to within an error of about 8% if the fair weather field estimate is typically within 1 V/m of the true fair weather field. Using this side constraint and data from fair weather field maneuvers taken on 29 June 2001, the Citation aircraft was calibrated. The resulting calibration matrix was then used to retrieve storm electric fields during a Citation flight on 2 June 2001. The storm field results are encouraging and agree favorably with the results obtained from earlier calibration analyses that were based on iterative techniques.

Biomimetic multifunctional surfaces inspired from animals.

PubMed

Han, Zhiwu; Mu, Zhengzhi; Yin, Wei; Li, Wen; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

2016-08-01

Over millions of years, animals have evolved to a higher intelligent level for their environment. A large number of diverse surface structures on their bodies have been formed to adapt to the extremely harsh environment. Just like the structural diversity existed in plants, the same also applies true in animals. Firstly, this article provides an overview and discussion of the most common functional surface structures inspired from animals, such as drag reduction, noise reduction, anti-adhesion, anti-wear, anti-erosion, anti-fog, water capture, and optical surfaces. Then, some typical characteristics of morphologies, structures, and materials of the animal multifunctional surfaces were discussed. The adaptation of these surfaces to environmental conditions was also analyzed. It mainly focuses on the relationship between their surface functions and their surface structural characteristics. Afterwards, the multifunctional mechanisms or principles of these surfaces were discussed. Models of these structures were provided for the development of structure materials and machinery surfaces. At last, fabrication techniques and existing or potential technical applications inspired from biomimetic multifunctional surfaces in animals were also discussed. The application prospects of the biomimetic functional surfaces are very broad, such as civil field of self-cleaning textile fabrics and non-stick pots, ocean field of oil-water separation, sports field of swimming suits, space development field of lens arrays. Copyright © 2016 Elsevier B.V. All rights reserved.

Electric field stabilization of viscous liquid layers coating the underside of a surface

NASA Astrophysics Data System (ADS)

Anderson, Thomas G.; Cimpeanu, Radu; Papageorgiou, Demetrios T.; Petropoulos, Peter G.

2017-05-01

We investigate the electrostatic stabilization of a viscous thin film wetting the underside of a horizontal surface in the presence of an electric field applied parallel to the surface. The model includes the effect of bounding solid dielectric regions above and below the liquid-air system that are typically found in experiments. The competition between gravitational forces, surface tension, and the nonlocal effect of the applied electric field is captured analytically in the form of a nonlinear evolution equation. A semispectral solution strategy is employed to resolve the dynamics of the resulting partial differential equation. Furthermore, we conduct direct numerical simulations (DNS) of the Navier-Stokes equations using the volume-of-fluid methodology and assess the accuracy of the obtained solutions in the long-wave (thin-film) regime when varying the electric field strength from zero up to the point when complete stabilization occurs. We employ DNS to examine the limitations of the asymptotically derived behavior as the liquid layer thickness increases and find excellent agreement even beyond the regime of strict applicability of the asymptotic solution. Finally, the asymptotic and computational approaches are utilized to identify robust and efficient active control mechanisms allowing the manipulation of the fluid interface in light of engineering applications at small scales, such as mixing.

Laser heating of scanning probe tips for thermal near-field spectroscopy and imaging

NASA Astrophysics Data System (ADS)

O'Callahan, Brian T.; Raschke, Markus B.

2017-02-01

Spectroscopy and microscopy of the thermal near-field yield valuable insight into the mechanisms of resonant near-field heat transfer and Casimir and Casimir-Polder forces, as well as providing nanoscale spatial resolution for infrared vibrational spectroscopy. A heated scanning probe tip brought close to a sample surface can excite and probe the thermal near-field. Typically, tip temperature control is provided by resistive heating of the tip cantilever. However, this requires specialized tips with limited temperature range and temporal response. By focusing laser radiation onto AFM cantilevers, we achieve heating up to ˜1800 K, with millisecond thermal response time. We demonstrate application to thermal infrared near-field spectroscopy (TINS) by acquiring near-field spectra of the vibrational resonances of silicon carbide, hexagonal boron nitride, and polytetrafluoroethylene. We discuss the thermal response as a function of the incident excitation laser power and model the dominant cooling contributions. Our results provide a basis for laser heating as a viable approach for TINS, nanoscale thermal transport measurements, and thermal desorption nano-spectroscopy.

A Novel Method Of Gradient Forming and Fluid Manipulation in Reduced Gravity Environments

NASA Technical Reports Server (NTRS)

Ramachandran N.; Leslie, F.

1999-01-01

The use of magnetic fields to control the motion and position of non-conducting liquids has received growing interest in recent times. The possibility of using the forces exerted by a nonuniform magnetic field on a ferrofluid to not only achieve fluid manipulation but also to actively control fluid motion makes it an attractive candidate for applications such as heat transfer in space systems. Terrestrial heat transfer equipment often relies on the normal gravitational force to hold liquid in a desired position or to provide a buoyant force to enhance the heat transfer rate. The residual gravitational force present in a space environment may no longer serve these useful functions and other forces, such as surface tension, can play a significant role in determining heat transfer rates. Although typically overwhelmed by gravitational forces in terrestrial applications, the body force induced in a ferrofluid by a nonuniform magnetic field can help to achieve these objectives in a microgravity environment. This paper will address the fluid manipulation aspect and will comprise of results from model fluid experiments and numerical modeling of the problem. Results from a novel method of forming concentration gradients that are applicable to low gravity applications will be presented. The ground based experiments are specifically tailored to demonstrate the magnetic manipulation capability of a ferrofluid and show that gravitational effects can be countered in carefully designed systems. The development of governing equations for the system will be presented along with a sampling of numerical results.

Application of laser Doppler velocimeter to chemical vapor laser system

NASA Technical Reports Server (NTRS)

Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

1993-01-01

A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

Synthesis of Graphene-Based Sensors and Application on Detecting SF6 Decomposing Products: A Review

PubMed Central

Zhang, Xiaoxing; Cui, Hao; Gui, Yingang

2017-01-01

Graphene-based materials have aroused enormous focus on a wide range of engineering fields because of their unique structure. One of the most promising applications is gas adsorption and sensing. In electrical engineering, graphene-based sensors are also employed as detecting devices to estimate the operation status of gas insulated switchgear (GIS). This paper reviews the main synthesis methods of graphene, gas adsorption, and sensing mechanism of its based sensors, as well as their applications in detecting SF6 decomposing products, such as SO2, H2S, SO2F2, and SOF2, in GIS. Both theoretical and experimental researches on gas response of graphene-based sensors to these typical gases are summarized. Finally, the future research trend about graphene synthesis technique and relevant perspective are also given. PMID:28208836

Force-controlled inorganic crystallization lithography.

PubMed

Cheng, Chao-Min; LeDuc, Philip R

2006-09-20

Lithography plays a key role in integrated circuits, optics, information technology, biomedical applications, catalysis, and separation technologies. However, inorganic lithography techniques remain of limited utility for applications outside of the typical foci of integrated circuit manufacturing. In this communication, we have developed a novel stamping method that applies pressure on the upper surface of the stamp to regulate the dewetting process of the inorganic buffer and the evaporation rate of the solvent in this buffer between the substrate and the surface of the stamp. We focused on generating inorganic microstructures with specific locations and also on enabling the ability to pattern gradients during the crystallization of the inorganic salts. This approach utilized a combination of lithography with bottom-up growth and assembly of inorganic crystals. This work has potential applications in a variety of fields, including studying inorganic material patterning and small-scale fabrication technology.

Meta-Chirality: Fundamentals, Construction and Applications

PubMed Central

Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Guo, Yinghui; Gao, Ping; Luo, Xiangang

2017-01-01

Chiral metamaterials represent a special type of artificial structures that cannot be superposed to their mirror images. Due to the lack of mirror symmetry, cross-coupling between electric and magnetic fields exist in chiral mediums and present unique electromagnetic characters of circular dichroism and optical activity, which provide a new opportunity to tune polarization and realize negative refractive index. Chiral metamaterials have attracted great attentions in recent years and have given rise to a series of applications in polarization manipulation, imaging, chemical and biological detection, and nonlinear optics. Here we review the fundamental theory of chiral media and analyze the construction principles of some typical chiral metamaterials. Then, the progress in extrinsic chiral metamaterials, absorbing chiral metamaterials, and reconfigurable chiral metamaterials are summarized. In the last section, future trends in chiral metamaterials and application in nonlinear optics are introduced. PMID:28513560

Single-shot coherent diffraction imaging of microbunched relativistic electron beams for free-electron laser applications.

PubMed

Marinelli, A; Dunning, M; Weathersby, S; Hemsing, E; Xiang, D; Andonian, G; O'Shea, F; Miao, Jianwei; Hast, C; Rosenzweig, J B

2013-03-01

With the advent of coherent x rays provided by the x-ray free-electron laser (FEL), strong interest has been kindled in sophisticated diffraction imaging techniques. In this Letter, we exploit such techniques for the diagnosis of the density distribution of the intense electron beams typically utilized in an x-ray FEL itself. We have implemented this method by analyzing the far-field coherent transition radiation emitted by an inverse-FEL microbunched electron beam. This analysis utilizes an oversampling phase retrieval method on the transition radiation angular spectrum to reconstruct the transverse spatial distribution of the electron beam. This application of diffraction imaging represents a significant advance in electron beam physics, having critical applications to the diagnosis of high-brightness beams, as well as the collective microbunching instabilities afflicting these systems.

Interface Schottky barrier engineering via strain in metal-semiconductor composites

NASA Astrophysics Data System (ADS)

Ma, Xiangchao; Dai, Ying; Yu, Lin; Huang, Baibiao

2016-01-01

The interfacial carrier transfer property, which is dominated by the interface Schottky barrier height (SBH), plays a crucial role in determining the performance of metal-semiconductor heterostructures in a variety of applications. Therefore, artificially controlling the interface SBH is of great importance for their industrial applications. As a model system, the Au/TiO2 (001) heterostructure is studied using first-principles calculations and the tight-binding method in the present study. Our investigation demonstrates that strain can be an effective way to decrease the interface SBH and that the n-type SBH can be more effectively decreased than the p-type SBH. Astonishingly, strain affects the interface SBH mainly by changing the intrinsic properties of Au and TiO2, whereas the interfacial potential alignment is almost independent of strain due to two opposite effects, which are induced by strain at the interfacial region. These observed trends can be understood on the basis of the general free-electron gas model of typical metals, the tight-binding theory and the crystal-field theory, which suggest that similar trends may be generalized for many other metal-semiconductor heterostructures. Given the commonness and tunability of strain in typical heterostructures, we anticipate that the tunability of the interface SBH with strain described here can provide an alternative effective way for realizing more efficient applications of relevant heterostructures.The interfacial carrier transfer property, which is dominated by the interface Schottky barrier height (SBH), plays a crucial role in determining the performance of metal-semiconductor heterostructures in a variety of applications. Therefore, artificially controlling the interface SBH is of great importance for their industrial applications. As a model system, the Au/TiO2 (001) heterostructure is studied using first-principles calculations and the tight-binding method in the present study. Our investigation demonstrates that strain can be an effective way to decrease the interface SBH and that the n-type SBH can be more effectively decreased than the p-type SBH. Astonishingly, strain affects the interface SBH mainly by changing the intrinsic properties of Au and TiO2, whereas the interfacial potential alignment is almost independent of strain due to two opposite effects, which are induced by strain at the interfacial region. These observed trends can be understood on the basis of the general free-electron gas model of typical metals, the tight-binding theory and the crystal-field theory, which suggest that similar trends may be generalized for many other metal-semiconductor heterostructures. Given the commonness and tunability of strain in typical heterostructures, we anticipate that the tunability of the interface SBH with strain described here can provide an alternative effective way for realizing more efficient applications of relevant heterostructures. Electronic supplementary information (ESI) available: The changes of Au 5d DOS, valence bands of TiO2, the interfacial bond length and interfacial energy with strain, and the local DOS results for the change of SBH with strain. See DOI: 10.1039/c5nr05583k

Magnetometry of single ferromagnetic nanoparticles using magneto-optical indicator films with spatial amplification

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

Balk, Andrew L., E-mail: andrew.balk@nist.gov; Maryland NanoCenter, University of Maryland, College Park, Maryland 20742; Hangarter, Carlos

2015-03-16

We present a magneto-optical technique to spatially amplify and image fringe fields from single ferromagnetic nanorods. The fringe fields nucleate magnetic domains in a low-coercivity, perpendicularly magnetized indicator film, which are expanded by an applied out-of-plane field from the nanoscale to the microscale for measurement with polar Kerr microscopy. The nucleation location and therefore magnetic orientation of the sample nanorod are detected as spatially dependent field biases in locally measured hysteresis loops of the indicator film. We first discuss our method to fabricate the high-sensitivity indicator film with low energy argon ion irradiation. We then present a map of themore » amplified signal produced from a single nanorod as measured by the indicator film and compare it with a simultaneously obtained, unamplified fringe field map. The comparison demonstrates the advantage of the amplification mechanism and the capability of the technique to be performed with single-spot magneto-optical Kerr effect magnetometers. Our signal-to-noise ratio determines a minimum measureable particle diameter of tens of nanometers for typical transition metals. We finally use our method to obtain hysteresis loops from multiple nanorods in parallel. Our technique is unperturbed by applied in-plane fields for magnetic manipulation of nanoparticles, is robust against many common noise sources, and is applicable in a variety of test environments. We conclude with a discussion of the future optimization and application of our indicator film technique.« less

LANL* V1.0: a radiation belt drift shell model suitable for real-time and reanalysis applications

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

Koller, Josep; Reeves, Geoffrey D; Friedel, Reiner H W

2008-01-01

Space weather modeling, forecasts, and predictions, especially for the radiation belts in the inner magnetosphere, require detailed information about the Earth's magnetic field. Results depend on the magnetic field model and the L* (pron. L-star) values which are used to describe particle drift shells. Space wather models require integrating particle motions along trajectories that encircle the Earth. Numerical integration typically takes on the order of 10{sup 5} calls to a magnetic field model which makes the L* calculations very slow, in particular when using a dynamic and more accurate magnetic field model. Researchers currently tend to pick simplistic models overmore » more accurate ones but also risking large inaccuracies and even wrong conclusions. For example, magnetic field models affect the calculation of electron phase space density by applying adiabatic invariants including the drift shell value L*. We present here a new method using a surrogate model based on a neural network technique to replace the time consuming L* calculations made with modern magnetic field models. The advantage of surrogate models (or meta-models) is that they can compute the same output in a fraction of the time while adding only a marginal error. Our drift shell model LANL* (Los Alamos National Lab L-star) is based on L* calculation using the TSK03 model. The surrogate model has currently been tested and validated only for geosynchronous regions but the method is generally applicable to any satellite orbit. Computations with the new model are several million times faster compared to the standard integration method while adding less than 1% error. Currently, real-time applications for forecasting and even nowcasting inner magnetospheric space weather is limited partly due to the long computing time of accurate L* values. Without them, real-time applications are limited in accuracy. Reanalysis application of past conditions in the inner magnetosphere are used to understand physical processes and their effect. Without sufficiently accurate L* values, the interpretation of reanalysis results becomes difficult and uncertain. However, with a method that can calculate accurate L* values orders of magnitude faster, analyzing whole solar cycles worth of data suddenly becomes feasible.« less

Pair interactions of heavy vortices in quantum fluids

NASA Astrophysics Data System (ADS)

Pshenichnyuk, Ivan A.

2018-02-01

The dynamics of quantum vortex pairs carrying heavy doping matter trapped inside their cores is studied. The nonlinear classical matter field formalism is used to build a universal mathematical model of a heavy vortex applicable to different types of quantum mixtures. It is shown how the usual vortex dynamics typical for undoped pairs qualitatively changes when heavy dopants are used: heavy vortices with opposite topological charges (chiralities) attract each other, while vortices with the same charge are repelled. The force responsible for such behavior appears as a result of superposition of vortices velocity fields in the presence of doping substance and can be considered as a special realization of the Magnus effect. The force is evaluated quantitatively and its inverse proportionality to the distance is demonstrated. The mechanism described in this paper gives an example of how a light nonlinear classical field may realize repulsive and attractive interactions between embedded heavy impurities.

AmeriFlux US-KUT KUOM Turfgrass Field

DOE Data Explorer

McFadden, Joe [University of California, Santa Barbara

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-KUT KUOM Turfgrass Field. Site Description - The site was a low-maintenace lawn consisting of cool-season turfgrasses, typical of residential lawns or urban parks in the study area. It was mowed to a height of 70 mm approximately once per week with clippings left to decompose on the surface, was not irrigated, and received one application of inorganic N fertilizer per year. The surrounding suburban residential neighborhood experienced rapid residential development in the 1950s; prior to that time, farms and nurseries were the predominant land-use types. Note that the land management of the field site changed (removal of the turfgrass lawn and planting of trees) AFTER the flux study was completed--this means that imagery after 2009 does not show the land conditions during the flux study.

Electric field-induced reversible trapping of microtubules along metallic glass microwire electrodes

NASA Astrophysics Data System (ADS)

Kim, Kyongwan; Sikora, Aurélien; Nakayama, Koji S.; Umetsu, Mitsuo; Hwang, Wonmuk; Teizer, Winfried

2015-04-01

Microtubules are among bio-polymers providing vital functions in dynamic cellular processes. Artificial organization of these bio-polymers is a requirement for transferring their native functions into device applications. Using electrophoresis, we achieve an accumulation of microtubules along a metallic glass (Pd42.5Cu30Ni7.5P20) microwire in solution. According to an estimate based on migration velocities of microtubules approaching the wire, the electrophoretic mobility of microtubules is around 10-12 m2/Vs. This value is four orders of magnitude smaller than the typical mobility reported previously. Fluorescence microscopy at the individual-microtubule level shows microtubules aligning along the wire axis during the electric field-induced migration. Casein-treated electrodes are effective to reversibly release trapped microtubules upon removal of the external field. An additional result is the condensation of secondary filamentous structures from oriented microtubules.

Field dynamics inference via spectral density estimation

NASA Astrophysics Data System (ADS)

Frank, Philipp; Steininger, Theo; Enßlin, Torsten A.

2017-11-01

Stochastic differential equations are of utmost importance in various scientific and industrial areas. They are the natural description of dynamical processes whose precise equations of motion are either not known or too expensive to solve, e.g., when modeling Brownian motion. In some cases, the equations governing the dynamics of a physical system on macroscopic scales occur to be unknown since they typically cannot be deduced from general principles. In this work, we describe how the underlying laws of a stochastic process can be approximated by the spectral density of the corresponding process. Furthermore, we show how the density can be inferred from possibly very noisy and incomplete measurements of the dynamical field. Generally, inverse problems like these can be tackled with the help of Information Field Theory. For now, we restrict to linear and autonomous processes. To demonstrate its applicability, we employ our reconstruction algorithm on a time-series and spatiotemporal processes.

Sensitivity Kernels for the Cross-Convolution Measure: Eliminate the Source in Waveform Tomography

NASA Astrophysics Data System (ADS)

Menke, W. H.

2017-12-01

We use the adjoint method to derive sensitivity kernels for the cross-convolution measure, a goodness-of-fit criterion that is applicable to seismic data containing closely-spaced multiple arrivals, such as reverberating compressional waves and split shear waves. In addition to a general formulation, specific expressions for sensitivity with respect to density, Lamé parameter and shear modulus are derived for a isotropic elastic solid. As is typical of adjoint methods, the kernels depend upon an adjoint field, the source of which, in this case, is the reference displacement field, pre-multiplied by a matrix of cross-correlations of components of the observed field. We use a numerical simulation to evaluate the resolving power of a topographic inversion that employs the cross-convolution measure. The estimated resolving kernel shows is point-like, indicating that the cross-convolution measure will perform well in waveform tomography settings.

Field dynamics inference via spectral density estimation.

PubMed

Frank, Philipp; Steininger, Theo; Enßlin, Torsten A

2017-11-01

Stochastic differential equations are of utmost importance in various scientific and industrial areas. They are the natural description of dynamical processes whose precise equations of motion are either not known or too expensive to solve, e.g., when modeling Brownian motion. In some cases, the equations governing the dynamics of a physical system on macroscopic scales occur to be unknown since they typically cannot be deduced from general principles. In this work, we describe how the underlying laws of a stochastic process can be approximated by the spectral density of the corresponding process. Furthermore, we show how the density can be inferred from possibly very noisy and incomplete measurements of the dynamical field. Generally, inverse problems like these can be tackled with the help of Information Field Theory. For now, we restrict to linear and autonomous processes. To demonstrate its applicability, we employ our reconstruction algorithm on a time-series and spatiotemporal processes.

Development of an automated high-temperature valveless injection system for online gas chromatography

NASA Astrophysics Data System (ADS)

Kreisberg, N. M.; Worton, D. R.; Zhao, Y.; Isaacman, G.; Goldstein, A. H.; Hering, S. V.

2014-12-01

A reliable method of sample introduction is presented for online gas chromatography with a special application to in situ field portable atmospheric sampling instruments. A traditional multi-port valve is replaced with a valveless sample introduction interface that offers the advantage of long-term reliability and stable sample transfer efficiency. An engineering design model is presented and tested that allows customizing this pressure-switching-based device for other applications. Flow model accuracy is within measurement accuracy (1%) when parameters are tuned for an ambient-pressure detector and 15% accurate when applied to a vacuum-based detector. Laboratory comparisons made between the two methods of sample introduction using a thermal desorption aerosol gas chromatograph (TAG) show that the new interface has approximately 3 times greater reproducibility maintained over the equivalent of a week of continuous sampling. Field performance results for two versions of the valveless interface used in the in situ instrument demonstrate typically less than 2% week-1 response trending and a zero failure rate during field deployments ranging up to 4 weeks of continuous sampling. Extension of the valveless interface to dual collection cells is presented with less than 3% cell-to-cell carryover.

Development of an automated high-temperature valveless injection system for online gas chromatography

DOE PAGES

Kreisberg, N. M.; Worton, D. R.; Zhao, Y.; ...

2014-12-12

A reliable method of sample introduction is presented for online gas chromatography with a special application to in situ field portable atmospheric sampling instruments. A traditional multi-port valve is replaced with a valveless sample introduction interface that offers the advantage of long-term reliability and stable sample transfer efficiency. An engineering design model is presented and tested that allows customizing this pressure-switching-based device for other applications. Flow model accuracy is within measurement accuracy (1%) when parameters are tuned for an ambient-pressure detector and 15% accurate when applied to a vacuum-based detector. Laboratory comparisons made between the two methods of sample introductionmore » using a thermal desorption aerosol gas chromatograph (TAG) show that the new interface has approximately 3 times greater reproducibility maintained over the equivalent of a week of continuous sampling. Field performance results for two versions of the valveless interface used in the in situ instrument demonstrate typically less than 2% week -1 response trending and a zero failure rate during field deployments ranging up to 4 weeks of continuous sampling. Extension of the valveless interface to dual collection cells is presented with less than 3% cell-to-cell carryover.« less

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

Kreisberg, N. M.; Worton, D. R.; Zhao, Y.

A reliable method of sample introduction is presented for online gas chromatography with a special application to in situ field portable atmospheric sampling instruments. A traditional multi-port valve is replaced with a valveless sample introduction interface that offers the advantage of long-term reliability and stable sample transfer efficiency. An engineering design model is presented and tested that allows customizing this pressure-switching-based device for other applications. Flow model accuracy is within measurement accuracy (1%) when parameters are tuned for an ambient-pressure detector and 15% accurate when applied to a vacuum-based detector. Laboratory comparisons made between the two methods of sample introductionmore » using a thermal desorption aerosol gas chromatograph (TAG) show that the new interface has approximately 3 times greater reproducibility maintained over the equivalent of a week of continuous sampling. Field performance results for two versions of the valveless interface used in the in situ instrument demonstrate typically less than 2% week -1 response trending and a zero failure rate during field deployments ranging up to 4 weeks of continuous sampling. Extension of the valveless interface to dual collection cells is presented with less than 3% cell-to-cell carryover.« less

Proposed radiofrequency phased-array excitation scheme for homogenous and localized 7-Tesla whole-body imaging based on full-wave numerical simulations.

PubMed

Abraham, Roney; Ibrahim, Tamer S

2007-02-01

In this article, a radiofrequency (RF) excitation scheme for 7-Tesla (T) whole-body applications is derived and analyzed using the finite difference time domain (FDTD) method. Important features of the proposed excitation scheme and coil (a potential 7T whole-body transverse electromagnetic [TEM] resonator design), from both operational and electromagnetic perspectives, are discussed. The choice of the coil's operational mode is unconventional; instead of the typical "homogenous mode," we use a mode that provides a null field in the center of the coil at low-field applications. Using a 3D FDTD implementation of Maxwell's equations, we demonstrate that the whole-body 7T TEM coil (tuned to the aforementioned unconventional mode and excited in an optimized near-field, phased-array fashion) can potentially provide 1) homogenous whole-slice (demonstrated in three axial, sagittal, and coronal slices) and 2) 3D localized (demonstrated in the heart) excitations. As RF power was not considered as a part of the optimization in several cases, the significant improvements achieved by whole-slice RF excitation came at the cost of considerable increases in RF power requirements. Copyright (c) 2007 Wiley-Liss, Inc.

Evolution of Radial Electric Field due to RMP-induced density pump-out

NASA Astrophysics Data System (ADS)

Groebner, R. J.; Smith, S. P.; Evans, T. E.; Chen, X.; Paz-Soldan, C.; Burrell, K. H.; Nazikian, R.; Grierson, B. A.; Moyer, R. A.; Orlov, D.; Chrystal, C.; McKee, G. R.

2014-10-01

The time history of shear in the ExB field during application of resonant 3D magnetic perturbations (RMP) in DIII-D is studied with CER spectroscopy. Application of the RMP typically causes density pump-out and can ultimately lead to ELM suppression. Thus, understanding the origin of the density transport is an important issue for understanding ELM suppression by this technique. One hypothesis is that the RMP causes a reduction of ExB shear at the pedestal top, which then allows for an increase in density transport. The ExB shear is examined in a new experiment in which the RMP was varied by a small amount around the threshold for causing density pump-out. In and on top of the pedestal, Er is observed to become more positive coincident with density pumpout. Er and its shear are examined over a range of RMP fields to determine if there is a relation between these quantities and the magnitude of density pumpout. Work supported in part by the US DOE under DE-FC02-04ER54698, DE-AC02-09CH11466, DE-FG02-05ER54809, DE-FG02-89ER53296, and DE-FG02-08ER54999.

ALLTEM Multi-Axis Electromagnetic Induction System Demonstration and Validation

DTIC Science & Technology

2011-11-17

fencing that test the capabilities of the platform systems Recently the Open Field area was reconfigured to emulate typical impact area conditions. The...surveyed. • Open field (indirect fire) The indirect fire subarea contains only three munition types that could be typically found at an impact area...direct fire subarea contains only three munition types that could be typically found at an impact area of a direct fire weapons range. These are 25 mm

2G HTS wires made on 30 μm thick Hastelloy substrate

NASA Astrophysics Data System (ADS)

Sundaram, A.; Zhang, Y.; Knoll, A. R.; Abraimov, D.; Brownsey, P.; Kasahara, M.; Carota, G. M.; Nakasaki, R.; Cameron, J. B.; Schwab, G.; Hope, L. V.; Schmidt, R. M.; Kuraseko, H.; Fukushima, T.; Hazelton, D. W.

2016-10-01

REBCO (RE = rare earth) based high temperature superconducting (HTS) wires are now being utilized for the development of electric and electromagnetic devices for various industrial, scientific and medical applications. In the last several years, the increasing efforts in using the so-called second generation (2G) HTS wires for some of the applications require a further increase in their engineering current density (J e). The applications are those typically related to high magnetic fields where the higher J e of a REBCO wire, in addition to its higher irreversibility fields and higher mechanical strength, is already a major advantage over other superconducting wires. An effective way to increase the J e is to decrease the total thickness of a wire, for which using a thinner substrate becomes an obvious and attractive approach. By using our IBAD-MOCVD (ion beam assisted deposition-metal organic chemical vapor deposition) technology we have successfully made 2G HTS wires using a Hastelloy® C276 substrate that is only 30 μm in thickness. By using this thinner substrate instead of the typical 50 μm thick substrate and with a same critical current (I c), the J e of a wire can be increased by 30% to 45% depending on the copper stabilizer thickness. In this paper, we report the fabrication and characterization of the 2G HTS wires made on the 30 μm thick Hastelloy® C276 substrate. It was shown that with the optimization in the processing protocol, the surface of the thinner Hastelloy® C276 substrate can be readily electropolished to the quality needed for the deposition of the buffer stack. Same in the architecture as that on the standard 50 μm thick substrate, the buffer stack made on the 30 μm thick substrate showed an in-plane texture with a Δϕ of around 6.7° in the LaMnO3 cap layer. Low-temperature in-field transport measurement results suggest that the wires on the thinner substrate had achieved equivalent superconducting performance, most importantly the I c, as those on the 50 μm thick substrate. It is expected the 2G HTS wires made on the 30 μm thick Hastelloy® C276 substrate, the thinnest and with the highest J e to date, will greatly benefit such applications as high field magnets and high current cables.

Strategy for the development of a smart NDVI camera system for outdoor plant detection and agricultural embedded systems.

PubMed

Dworak, Volker; Selbeck, Joern; Dammer, Karl-Heinz; Hoffmann, Matthias; Zarezadeh, Ali Akbar; Bobda, Christophe

2013-01-24

The application of (smart) cameras for process control, mapping, and advanced imaging in agriculture has become an element of precision farming that facilitates the conservation of fertilizer, pesticides, and machine time. This technique additionally reduces the amount of energy required in terms of fuel. Although research activities have increased in this field, high camera prices reflect low adaptation to applications in all fields of agriculture. Smart, low-cost cameras adapted for agricultural applications can overcome this drawback. The normalized difference vegetation index (NDVI) for each image pixel is an applicable algorithm to discriminate plant information from the soil background enabled by a large difference in the reflectance between the near infrared (NIR) and the red channel optical frequency band. Two aligned charge coupled device (CCD) chips for the red and NIR channel are typically used, but they are expensive because of the precise optical alignment required. Therefore, much attention has been given to the development of alternative camera designs. In this study, the advantage of a smart one-chip camera design with NDVI image performance is demonstrated in terms of low cost and simplified design. The required assembly and pixel modifications are described, and new algorithms for establishing an enhanced NDVI image quality for data processing are discussed.

Application of hydrometallurgy techniques in quartz processing and purification: a review

NASA Astrophysics Data System (ADS)

Lin, Min; Lei, Shaomin; Pei, Zhenyu; Liu, Yuanyuan; Xia, Zhangjie; Xie, Feixiang

2018-04-01

Although there have been numerous studies on separation and purification of metallic minerals by hydrometallurgy techniques, applications of the chemical techniques in separation and purification of non-metallic minerals are rarely reported. This paper reviews disparate areas of study into processing and purification of quartz (typical non-metallic ore) in an attempt to summarize current work, as well as to suggest potential for future consolidation in the field. The review encompasses chemical techniques of the quartz processing including situations, progresses, leaching mechanism, scopes of application, advantages and drawbacks of micro-bioleaching, high temperature leaching, high temperature pressure leaching and catalyzed high temperature pressure leaching. Traditional leaching techniques including micro-bioleaching and high temperature leaching are unequal to demand of modern glass industry for quality of quartz concentrate because the quartz products has to be further processed. High temperature pressure leaching and catalyzed high temperature pressure leaching provide new ways to produce high-grade quartz sand with only one process and lower acid consumption. Furthermore, the catalyzed high temperature pressure leaching realizes effective purification of quartz with extremely low acid consumption (no using HF or any fluoride). It is proposed that, by integrating the different chemical processes of quartz processing and expounding leaching mechanisms and scopes of application, the research field as a monopolized industry would benefit.

Strategy for the Development of a Smart NDVI Camera System for Outdoor Plant Detection and Agricultural Embedded Systems

PubMed Central

Dworak, Volker; Selbeck, Joern; Dammer, Karl-Heinz; Hoffmann, Matthias; Zarezadeh, Ali Akbar; Bobda, Christophe

2013-01-01

The application of (smart) cameras for process control, mapping, and advanced imaging in agriculture has become an element of precision farming that facilitates the conservation of fertilizer, pesticides, and machine time. This technique additionally reduces the amount of energy required in terms of fuel. Although research activities have increased in this field, high camera prices reflect low adaptation to applications in all fields of agriculture. Smart, low-cost cameras adapted for agricultural applications can overcome this drawback. The normalized difference vegetation index (NDVI) for each image pixel is an applicable algorithm to discriminate plant information from the soil background enabled by a large difference in the reflectance between the near infrared (NIR) and the red channel optical frequency band. Two aligned charge coupled device (CCD) chips for the red and NIR channel are typically used, but they are expensive because of the precise optical alignment required. Therefore, much attention has been given to the development of alternative camera designs. In this study, the advantage of a smart one-chip camera design with NDVI image performance is demonstrated in terms of low cost and simplified design. The required assembly and pixel modifications are described, and new algorithms for establishing an enhanced NDVI image quality for data processing are discussed. PMID:23348037

Evaluation of metal-foil strain gages for cryogenic application in magnetic fields

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

Freynik, H.S. Jr.; Roach, D.R.; Deis, D.W.

1977-07-08

The requirement for the design and construction of large superconducting magnet systems for fusion research has raised a number of new questions regarding the properties of composite superconducting conductors. One of these, the effect of mechanical stress on the current-carrying capacity of Nb/sub 3/Sn, is of major importance in determining the feasibility of constructing large magnets with this material. A typical experiment for determining such data involves the measurement of critical current versus magnetic field while the conductor is being mechanically strained to various degrees. Techniques are well developed for the current and field measurements, but much less so formore » the accurate measurement of strain at liquid-helium temperature in a high magnetic field. A study was made of commercial, metal-foil strain gages for use under these conditions. The information developed can also be applied to the use of strain gages as diagnostic tools in superconducting magnets.« less

Comparative efficiency and driving range of light- and heavy-duty vehicles powered with biomass energy stored in liquid fuels or batteries

PubMed Central

Laser, Mark; Lynd, Lee R.

2014-01-01

This study addresses the question, “When using cellulosic biomass for vehicular transportation, which field-to-wheels pathway is more efficient: that using biofuels or that using bioelectricity?” In considering the question, the level of assumed technological maturity significantly affects the comparison, as does the intended transportation application. Results from the analysis indicate that for light-duty vehicles, over ranges typical in the United States today (e.g., 560–820 miles), field-to-wheels performance is similar, with some scenarios showing biofuel to be more efficient, and others indicating the two pathways to be essentially the same. Over the current range of heavy-duty vehicles, the field-to-wheels efficiency is higher for biofuels than for electrically powered vehicles. Accounting for technological advances and range, there is little basis to expect mature bioelectricity-powered vehicles to have greater field-to-wheels efficiency (e.g., kilometers per gigajoule biomass or per hectare) compared with mature biofuel-powered vehicles. PMID:24550477

Localization of incipient tip vortex cavitation using ray based matched field inversion method

NASA Astrophysics Data System (ADS)

Kim, Dongho; Seong, Woojae; Choo, Youngmin; Lee, Jeunghoon

2015-10-01

Cavitation of marine propeller is one of the main contributing factors of broadband radiated ship noise. In this research, an algorithm for the source localization of incipient vortex cavitation is suggested. Incipient cavitation is modeled as monopole type source and matched-field inversion method is applied to find the source position by comparing the spatial correlation between measured and replicated pressure fields at the receiver array. The accuracy of source localization is improved by broadband matched-field inversion technique that enhances correlation by incoherently averaging correlations of individual frequencies. Suggested localization algorithm is verified through known virtual source and model test conducted in Samsung ship model basin cavitation tunnel. It is found that suggested localization algorithm enables efficient localization of incipient tip vortex cavitation using a few pressure data measured on the outer hull above the propeller and practically applicable to the typically performed model scale experiment in a cavitation tunnel at the early design stage.

Precipitation-runoff relations and water-quality characteristics at edge-of-field stations, Discovery Farms and Pioneer Farm, Wisconsin, 2003-8

USGS Publications Warehouse

Stuntebeck, Todd D.; Komiskey, Matthew J.; Peppler, Marie C.; Owens, David W.; Frame, Dennis R.

2011-01-01

A cooperative study between the U.S. Geological Survey, the University of Wisconsin (UW)-Madison Discovery Farms program (Discovery Farms), and the UW-Platteville Pioneer Farm program (Pioneer Farm) was developed to identify typical ranges and magnitudes, temporal distributions, and principal factors affecting concentrations and yields of sediment, nutrients, and other selected constituents in runoff from agricultural fields. Hydrologic and water-quality data were collected year-round at 23 edge-of-field monitoring stations on 5 privately owned Discovery Farms and on Pioneer Farm during water years 2003-8. The studied farms represented landscapes, soils, and farming systems typical of livestock farms throughout southern Wisconsin. Each farm employed a variety of soil, nutrient, and water-conservation practices to help minimize sediment and nutrient losses from fields and to improve crop productivity. This report summarizes the precipitation-runoff relations and water-quality characteristics measured in edge-of-field runoff for 26 "farm years" (aggregate years of averaged station data from all 6 farms for varying monitoring periods). A relatively wide range of constituents typically found in agricultural runoff were measured: suspended sediment, phosphorus (total, particulate, dissolved reactive, and total dissolved), and nitrogen (total, nitrate plus nitrite, organic, ammonium, total Kjeldahl and total Kjeldahl-dissolved), chloride, total solids, total suspended solids, total volatile suspended solids, and total dissolved solids. Mean annual precipitation was 32.8 inches for the study period, about 3 percent less than the 30-year mean. Overall mean annual runoff was 2.55 inches per year (about 8 percent of precipitation) and the distribution was nearly equal between periods of frozen ground (54 percent) and unfrozen ground (46 percent). Mean monthly runoff was highest during two periods: February to March and May to June. Ninety percent of annual runoff occurred between January and the end of June. Event mean concentrations of suspended sediment in runoff during unfrozen-ground periods were significantly higher (p2= 0.92), indicating that the sources of nitrogen and phosphorus in runoff were likely similar. Analysis of runoff, concentration, and yield data on annual, monthly, and seasonal time scales, when combined with precipitation, soil moisture, soil temperature, and on-farm field-activity information, revealed conditions in which runoff was most likely. The analysis also revealed the effects that field conditions and the timing of field-management activities-most notably, manure applications and tillage-had on the quantity and quality of surface runoff from agricultural fields.

Adaptive pixel-super-resolved lensfree in-line digital holography for wide-field on-chip microscopy.

PubMed

Zhang, Jialin; Sun, Jiasong; Chen, Qian; Li, Jiaji; Zuo, Chao

2017-09-18

High-resolution wide field-of-view (FOV) microscopic imaging plays an essential role in various fields of biomedicine, engineering, and physical sciences. As an alternative to conventional lens-based scanning techniques, lensfree holography provides a new way to effectively bypass the intrinsical trade-off between the spatial resolution and FOV of conventional microscopes. Unfortunately, due to the limited sensor pixel-size, unpredictable disturbance during image acquisition, and sub-optimum solution to the phase retrieval problem, typical lensfree microscopes only produce compromised imaging quality in terms of lateral resolution and signal-to-noise ratio (SNR). Here, we propose an adaptive pixel-super-resolved lensfree imaging (APLI) method which can solve, or at least partially alleviate these limitations. Our approach addresses the pixel aliasing problem by Z-scanning only, without resorting to subpixel shifting or beam-angle manipulation. Automatic positional error correction algorithm and adaptive relaxation strategy are introduced to enhance the robustness and SNR of reconstruction significantly. Based on APLI, we perform full-FOV reconstruction of a USAF resolution target (~29.85 mm 2 ) and achieve half-pitch lateral resolution of 770 nm, surpassing 2.17 times of the theoretical Nyquist-Shannon sampling resolution limit imposed by the sensor pixel-size (1.67µm). Full-FOV imaging result of a typical dicot root is also provided to demonstrate its promising potential applications in biologic imaging.

Uncertainties in Air Exchange using Continuous-Injection, Long-Term Sampling Tracer-Gas Methods

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

Sherman, Max H.; Walker, Iain S.; Lunden, Melissa M.

2013-12-01

The PerFluorocarbon Tracer (PFT) method is a low-cost approach commonly used for measuring air exchange in buildings using tracer gases. It is a specific application of the more general Continuous-Injection, Long-Term Sampling (CILTS) method. The technique is widely used but there has been little work on understanding the uncertainties (both precision and bias) associated with its use, particularly given that it is typically deployed by untrained or lightly trained people to minimize experimental costs. In this article we will conduct a first-principles error analysis to estimate the uncertainties and then compare that analysis to CILTS measurements that were over-sampled, throughmore » the use of multiple tracers and emitter and sampler distribution patterns, in three houses. We find that the CILTS method can have an overall uncertainty of 10-15percent in ideal circumstances, but that even in highly controlled field experiments done by trained experimenters expected uncertainties are about 20percent. In addition, there are many field conditions (such as open windows) where CILTS is not likely to provide any quantitative data. Even avoiding the worst situations of assumption violations CILTS should be considered as having a something like a ?factor of two? uncertainty for the broad field trials that it is typically used in. We provide guidance on how to deploy CILTS and design the experiment to minimize uncertainties.« less

An evaluation of the state of time synchronization on leadership class supercomputers

DOE PAGES

Jones, Terry; Ostrouchov, George; Koenig, Gregory A.; ...

2017-10-09

We present a detailed examination of time agreement characteristics for nodes within extreme-scale parallel computers. Using a software tool we introduce in this paper, we quantify attributes of clock skew among nodes in three representative high-performance computers sited at three national laboratories. Our measurements detail the statistical properties of time agreement among nodes and how time agreement drifts over typical application execution durations. We discuss the implications of our measurements, why the current state of the field is inadequate, and propose strategies to address observed shortcomings.

Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data

DOE PAGES

Strait, E. J.; King, J. D.; Hanson, J. M.; ...

2016-08-11

An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric "3D" features of tokamak plasmas, with typical amplitudes ~10 -3 to 10 -5 of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Lastly, applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.

Novel quad-band terahertz metamaterial absorber based on single pattern U-shaped resonator

NASA Astrophysics Data System (ADS)

Wang, Ben-Xin; Wang, Gui-Zhen

2017-03-01

A novel quad-band terahertz metamaterial absorber using four different modes of single pattern resonator is demonstrated. Four obvious frequencies with near-perfect absorption are realized. Near-field distributions of the four modes are provided to reveal the physical picture of the multiple-band absorption. Unlike most previous quad-band absorbers that typically require four or more patterns, the designed absorber has only one resonant structure, which is simpler than previous works. The presented quad-band absorber has potential applications in biological sensing, medical imaging, and material detection.

Flow visualization of film cooling with spanwise injection from a small array of holes and compound-angle injection from a large array

NASA Technical Reports Server (NTRS)

Russell, L. M.

1978-01-01

Film injection from discrete holes in a smooth, flat plate was studied for two configurations: (1) spanwise injection through a four hole staggered array; and (2) compound angle injection through a 49 hole staggered array. The ratio of boundary layer thicknesses to hole diameter and the Reynolds number were typical of gas turbine film cooling applications. Streaklines showing the motion of the injected air were obtained by photographing small, neutrally buoyant, helium-filled soap bubbles that followed the flow field.

An evaluation of the state of time synchronization on leadership class supercomputers

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

Jones, Terry; Ostrouchov, George; Koenig, Gregory A.

We present a detailed examination of time agreement characteristics for nodes within extreme-scale parallel computers. Using a software tool we introduce in this paper, we quantify attributes of clock skew among nodes in three representative high-performance computers sited at three national laboratories. Our measurements detail the statistical properties of time agreement among nodes and how time agreement drifts over typical application execution durations. We discuss the implications of our measurements, why the current state of the field is inadequate, and propose strategies to address observed shortcomings.

How social impact assessment can contribute to conflict management

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

Prenzel, Paula V., E-mail: p.v.prenzel@student.rug.nl; Vanclay, Frank, E-mail: frank.vanclay@rug.nl

2014-02-15

The potential for conflict is omnipresent in all projects, and even in all human interactions, and conflict itself leads to many second-order social impacts. This article examines the contribution of the methodological approach used in social impact assessment (SIA) to conflict management. We view conflict as a process that has its own dynamic, and is to be expected in all situations. By using game theory (prisoner's dilemma), we describe and conceptualize this process and highlight the importance of communication in managing conflict. We demonstrate the potential use of SIA in preventing, managing and resolving conflict. Emphasis is placed on themore » participatory character of SIA and the role of public media. In contrast to existing literature, our focus is not restricted to the typical fields of study of SIA (e.g. environmental conflicts), but understands conflict itself as a field of application. In this sense, conflict-sensitive SIA can be understood both as an extension to the SIA tool kit and a broadening of the scope of SIA application. -- Highlights: • Conflict is omnipresent and creates both positive and negative social impacts. • Conflict itself represents a possible field of application for SIA. • Conflict escalation is a process that can be modeled in a game-theoretic framework. • There needs to be concerted effort to prevent escalation to avoid harmful outcomes. • Conflict-sensitive SIA can support conflict management and sustainable resolution.« less

Hybrid magnet devices for molecule manipulation and small scale high gradient-field applications

DOEpatents

Humphries, David E [El Cerrito, CA; Hong, Seok-Cheol [Seoul, KR; Cozzarelli, legal representative, Linda A.; Pollard, Martin J [El Cerrito, CA; Cozzarelli, Nicholas R [Berkeley, CA

2009-01-06

The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetizable molecular structures and targets. Also disclosed are hybrid magnetic tweezers able to exert approximately 1 nN of force to 4.5 .mu.m magnetic bead. The maximum force was experimentally measured to be .about.900 pN which is in good agreement with theoretical estimations and other measurements. In addition, a new analysis scheme that permits fast real-time position measurement in typical geometry of magnetic tweezers has been developed and described in detail.

Residential Fuel Cell Demonstration Handbook

NASA Astrophysics Data System (ADS)

Torrero, E.; McClelland, R.

2002-07-01

This report is a guide for rural electric cooperatives engaged in field testing of equipment and in assessing related application and market issues. Dispersed generation and its companion fuel cell technology have attracted increased interest by rural electric cooperatives and their customers. In addition, fuel cells are a particularly interesting source because their power quality, efficiency, and environmental benefits have now been coupled with major manufacturer development efforts. The overall effort is structured to measure the performance, durability, reliability, and maintainability of these systems, to identify promising types of applications and modes of operation, and to assess the related prospect for future use. In addition, technical successes and shortcomings will be identified by demonstration participants and manufacturers using real-world experience garnered under typical operating environments.

Statistical analysis of field data for aircraft warranties

NASA Astrophysics Data System (ADS)

Lakey, Mary J.

Air Force and Navy maintenance data collection systems were researched to determine their scientific applicability to the warranty process. New and unique algorithms were developed to extract failure distributions which were then used to characterize how selected families of equipment typically fails. Families of similar equipment were identified in terms of function, technology and failure patterns. Statistical analyses and applications such as goodness-of-fit test, maximum likelihood estimation and derivation of confidence intervals for the probability density function parameters were applied to characterize the distributions and their failure patterns. Statistical and reliability theory, with relevance to equipment design and operational failures were also determining factors in characterizing the failure patterns of the equipment families. Inferences about the families with relevance to warranty needs were then made.

Resolution requirements for aero-optical simulations

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

Mani, Ali; Wang Meng; Moin, Parviz

2008-11-10

Analytical criteria are developed to estimate the error of aero-optical computations due to inadequate spatial resolution of refractive index fields in high Reynolds number flow simulations. The unresolved turbulence structures are assumed to be locally isotropic and at low turbulent Mach number. Based on the Kolmogorov spectrum for the unresolved structures, the computational error of the optical path length is estimated and linked to the resulting error in the computed far-field optical irradiance. It is shown that in the high Reynolds number limit, for a given geometry and Mach number, the spatial resolution required to capture aero-optics within a pre-specifiedmore » error margin does not scale with Reynolds number. In typical aero-optical applications this resolution requirement is much lower than the resolution required for direct numerical simulation, and therefore, a typical large-eddy simulation can capture the aero-optical effects. The analysis is extended to complex turbulent flow simulations in which non-uniform grid spacings are used to better resolve the local turbulence structures. As a demonstration, the analysis is used to estimate the error of aero-optical computation for an optical beam passing through turbulent wake of flow over a cylinder.« less

Assessment of relevant factors and relationships concerning human dermal exposure to pesticides in greenhouse applications.

PubMed

Martínez Vidal, Jose L; Egea González, Francisco J; Garrido Frenich, Antonia; Martínez Galera, María; Aguilera, Pedro A; López Carrique, Enrique

2002-08-01

Principal component analysis (PCA) was applied to the gas chromatographic data obtained from 23 different greenhouse trials. This was used to establish which factors, including application technique (very small, small, medium and large drop-size), crop characteristics (short/tall, thin/dense) and pattern application of the operator (walking towards or away from the treated area) are relevant to the dermal exposure levels of greenhouse applicators. The results showed that the highest exposure by pesticides during field applications in greenhouses, in the climatic conditions and in the crop conditions typical of a southern European country, occurs on the lower legs and front thighs of the applicators. Similar results were obtained by hierarchical cluster analysis (HCA). Drop-size seems to be very important in determining total exposure, while height and density of crops have little influence on total exposure under the conditions of the present study. No pesticide type is a major factor in total exposure. The application of multiple regression analysis (MRA) allowed assessment of the relationships between the pesticide exposure of the less affected parts of the body with the most affected parts.

Laccase: microbial sources, production, purification, and potential biotechnological applications.

PubMed

Shraddha; Shekher, Ravi; Sehgal, Simran; Kamthania, Mohit; Kumar, Ajay

2011-01-01

Laccase belongs to the blue multicopper oxidases and participates in cross-linking of monomers, degradation of polymers, and ring cleavage of aromatic compounds. It is widely distributed in higher plants and fungi. It is present in Ascomycetes, Deuteromycetes and Basidiomycetes and abundant in lignin-degrading white-rot fungi. It is also used in the synthesis of organic substance, where typical substrates are amines and phenols, the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. In the recent years, these enzymes have gained application in the field of textile, pulp and paper, and food industry. Recently, it is also used in the design of biosensors, biofuel cells, as a medical diagnostics tool and bioremediation agent to clean up herbicides, pesticides and certain explosives in soil. Laccases have received attention of researchers in the last few decades due to their ability to oxidize both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants. It has been identified as the principal enzyme associated with cuticular hardening in insects. Two main forms have been found: laccase-1 and laccase-2. This paper reviews the occurrence, mode of action, general properties, production, applications, and immobilization of laccases within different industrial fields.

Effects of dried wastewater-treatment sludge application on ground-water quality in South Dade County, Florida

USGS Publications Warehouse

Howie, Barbara

1992-01-01

Four test fields in the south Dade agricultural area were studied to determine the effects of sludge application on ground-water quality. Two fields had been cultivated for 10 years or more, and two had not been farmed for at least 10 years. The fields were representative of the area's two soil types (Rockdale and Perrine marl) and two major crop types (row crops and groves). Before the application of sludge, wells upgradient of, within, and downgradient of each field were sampled for possible sludge contaminants at the end of wet and dry seasons. Municipal wastewater treatment sludge from the Dade County Water and Sewe Authority Department was then applied to the fields at varying application rates. The wells at each field were sampled over a 2-year period under different hydrologic conditions for possible sludge-related constituents (specific conductance, pH, alkalinity, nitrogen, phosphorus, total organic carbon, copper, iron, magnesium, manganese, potassium, zinc, arsenic, cadmium, chloride, chromium, lead, mercury, nickel, and sodium). Comparisons were made between water quality in the vicinity of the test fields and Florida Department of Environmental Regulation primary and secondary drinking-water regulations, an between water quality upgradient of, beneath, and downgradient of the fields. Comparisons between presludge and postsludge water quality did not indicate any improvement because of retention of agrichemicals by the sludge nor did they indicate any deterioration because of leaching from the sludge. Comparisons of water quality upgradient of the fields to water quality beneath and downgradient of the fields also did not indicate any changes related to sludge. Florida Department of Environmental Regulation primary and secondary drinking-water regulations wer exceeded at the Rockdale maximum-application field by mercury (9.5 ug/L (micrograms per liter)), and the Perrine marl maximum-application field by manganese (60 ug/L) and lead (85 ug/L), and at the Perrine marl row-crop field by mercury (5.2 ug/L). All other exceedances were either in presludge or upgradient samples, or they were for constituents or properties, such as iron and color, which typically exceed standards in native ground water. Acid-extractable and base-neutral compounds, volatile organic compounds, chlorophenoxy herbicides, organophosphorus insecticides, and organochlorine compounds were analyzed for one shallow well at each field twice annually. Those compounds that equaled or exceeded the detection limit after sludge was applied included benzene (0.3 and 1.2 ug/L), chloroform (0.2 and 0.3 ug/L), bis(2-Ethylhexyl)phthalate (29 and 42 ug/L), methylene chloride (14 ug/L), tolulene (0.2, 0.4, 0.5, 1.3, and 4.4 ug/L), 1, 1,1-trichloroethana (0.6 ug/L), trichloroethylene (0.3 ug/L), 2.4-D (0.01 ug/L), and xylene (0.3 ug/L). It ws not possible to ascertain the origin of these compounds becuase they are available from sources other than sludge.

MD simulation study of direct permeation of a nanoparticle across the cell membrane under an external electric field.

PubMed

Shimizu, Kenta; Nakamura, Hideya; Watano, Satoru

2016-06-09

Nanoparticles (NPs) have been attracting much attention for biomedical and pharmaceutical applications. In most of the applications, NPs are required to translocate across the cell membrane and to reach the cell cytosol. Experimental studies have reported that by applying an electric field NPs can directly permeate across the cell membrane without the confinement of NPs by endocytic vesicles. However, damage to the cell can often be a concern. Understanding of the mechanism underlying the direct permeation of NPs under an external electric field can greatly contribute to the realization of a technology for the direct delivery of NPs. Here we investigated the permeation of a cationic gold NP across a phospholipid bilayer under an external electric field using a coarse-grained molecular dynamics simulation. When an external electric field that is equal to the membrane breakdown intensity was applied, a typical NP delivery by electroporation was shown: the cationic gold NP directly permeated across a lipid bilayer without membrane wrapping of the NP, while a persistent transmembrane pore was formed. However, when a specific range of the electric field that is lower than the membrane breakdown intensity was applied, a unique permeation pathway was exhibited: the generated transmembrane pore immediately resealed after the direct permeation of NP. Furthermore, we found that the affinity of the NP for the membrane surface is a key for the self-resealing of the pore. Our finding suggests that by applying an electric field in a suitable range NPs can be directly delivered into the cell with less cellular damage.

Cone of Darkness: Finding Blank-sky Positions for Multi-object Wide-field Observations

NASA Astrophysics Data System (ADS)

Lorente, N. P. F.

2014-05-01

We present the Cone of Darkness, an application to automatically configure blank-sky positions for a series of stacked, wide-field observations, such as those carried out by the SAMI instrument on the Anglo-Australian Telescope (AAT). The Sydney-AAO Multi-object Integral field spectrograph (SAMI) uses a plug-plate to mount its 13×61 core imaging fibre bundles (hexabundles) in the optical plane at the telescope's prime focus. To make the most efficient use of each plug-plate, several observing fields are typically stacked to produce a single plate. When choosing blank-sky positions for the observations it is most effective to select these such that one set of 26 holes gives valid sky positions for all fields on the plate. However, when carried out manually this selection process is tedious and includes a significant risk of error. The Cone of Darkness software aims to provide uniform blank-sky position coverage over the field of observation, within the limits set by the distribution of target positions and the chosen input catalogs. This will then facilitate the production of the best representative median sky spectrum for use in sky subtraction. The application, written in C++, is configurable, making it usable for a range of instruments. Given the plate characteristics and the positions of target holes, the software segments the unallocated space on the plate and determines the position which best fits the uniform distribution requirement. This position is checked, for each field, against the selected catalog using a TAP ADQL search. The process is then repeated until the desired number of sky positions is attained.

Electromagnetic receiver with capacitive electrodes and triaxial induction coil for tunnel exploration

NASA Astrophysics Data System (ADS)

Kai, Chen; Sheng, Jin; Wang, Shun

2017-09-01

A new type of electromagnetic (EM) receiver has been developed by integrating four capacitive electrodes and a triaxial induction coil with an advanced data logger for tunnel exploration. The new EM receiver can conduct EM observations in tunnels, which is one of the principal goals of surface-tunnel-borehole EM detection for deep ore deposit mapping. The use of capacitive electrodes enables us to record the electrical field (E-field) signals from hard rock surfaces, which are high-resistance terrains. A compact triaxial induction coil integrates three independent induction coils for narrow-tunnel exploration applications. A low-time-drift-error clock source is developed for tunnel applications where GPS signals are unavailable. The three main components of our tunnel EM receiver are: (1) four capacitive electrodes for measuring the E-field signal without digging in hard rock regions; (2) a triaxial induction coil sensor for audio-frequency magnetotelluric and controlled-source audio-frequency magnetotelluric signal measurements; and (3) a data logger that allows us to record five-component MT signals with low noise levels, low time-drift-error for the clock source, and high dynamic range. The proposed tunnel EM receiver was successfully deployed in a mine that exhibited with typical noise characteristics. [Figure not available: see fulltext. Caption: The new EM receiver can conduct EM observations in tunnels, which is one of the principal goals of the surface-tunnel-borehole EM (STBEM) detection for deep ore deposit mapping. The use of a capacitive electrode enables us to record the electrical field (E-field) signals from hard rock surfaces. A compact triaxial induction coil integrated three induction coils, for narrow-tunnel applications.

Unmanned Aerial Vehicle Remote Sensing for Field-Based Crop Phenotyping: Current Status and Perspectives.

PubMed

Yang, Guijun; Liu, Jiangang; Zhao, Chunjiang; Li, Zhenhong; Huang, Yanbo; Yu, Haiyang; Xu, Bo; Yang, Xiaodong; Zhu, Dongmei; Zhang, Xiaoyan; Zhang, Ruyang; Feng, Haikuan; Zhao, Xiaoqing; Li, Zhenhai; Li, Heli; Yang, Hao

2017-01-01

Phenotyping plays an important role in crop science research; the accurate and rapid acquisition of phenotypic information of plants or cells in different environments is helpful for exploring the inheritance and expression patterns of the genome to determine the association of genomic and phenotypic information to increase the crop yield. Traditional methods for acquiring crop traits, such as plant height, leaf color, leaf area index (LAI), chlorophyll content, biomass and yield, rely on manual sampling, which is time-consuming and laborious. Unmanned aerial vehicle remote sensing platforms (UAV-RSPs) equipped with different sensors have recently become an important approach for fast and non-destructive high throughput phenotyping and have the advantage of flexible and convenient operation, on-demand access to data and high spatial resolution. UAV-RSPs are a powerful tool for studying phenomics and genomics. As the methods and applications for field phenotyping using UAVs to users who willing to derive phenotypic parameters from large fields and tests with the minimum effort on field work and getting highly reliable results are necessary, the current status and perspectives on the topic of UAV-RSPs for field-based phenotyping were reviewed based on the literature survey of crop phenotyping using UAV-RSPs in the Web of Science™ Core Collection database and cases study by NERCITA. The reference for the selection of UAV platforms and remote sensing sensors, the commonly adopted methods and typical applications for analyzing phenotypic traits by UAV-RSPs, and the challenge for crop phenotyping by UAV-RSPs were considered. The review can provide theoretical and technical support to promote the applications of UAV-RSPs for crop phenotyping.

Unmanned Aerial Vehicle Remote Sensing for Field-Based Crop Phenotyping: Current Status and Perspectives

PubMed Central

Yang, Guijun; Liu, Jiangang; Zhao, Chunjiang; Li, Zhenhong; Huang, Yanbo; Yu, Haiyang; Xu, Bo; Yang, Xiaodong; Zhu, Dongmei; Zhang, Xiaoyan; Zhang, Ruyang; Feng, Haikuan; Zhao, Xiaoqing; Li, Zhenhai; Li, Heli; Yang, Hao

2017-01-01

Phenotyping plays an important role in crop science research; the accurate and rapid acquisition of phenotypic information of plants or cells in different environments is helpful for exploring the inheritance and expression patterns of the genome to determine the association of genomic and phenotypic information to increase the crop yield. Traditional methods for acquiring crop traits, such as plant height, leaf color, leaf area index (LAI), chlorophyll content, biomass and yield, rely on manual sampling, which is time-consuming and laborious. Unmanned aerial vehicle remote sensing platforms (UAV-RSPs) equipped with different sensors have recently become an important approach for fast and non-destructive high throughput phenotyping and have the advantage of flexible and convenient operation, on-demand access to data and high spatial resolution. UAV-RSPs are a powerful tool for studying phenomics and genomics. As the methods and applications for field phenotyping using UAVs to users who willing to derive phenotypic parameters from large fields and tests with the minimum effort on field work and getting highly reliable results are necessary, the current status and perspectives on the topic of UAV-RSPs for field-based phenotyping were reviewed based on the literature survey of crop phenotyping using UAV-RSPs in the Web of Science™ Core Collection database and cases study by NERCITA. The reference for the selection of UAV platforms and remote sensing sensors, the commonly adopted methods and typical applications for analyzing phenotypic traits by UAV-RSPs, and the challenge for crop phenotyping by UAV-RSPs were considered. The review can provide theoretical and technical support to promote the applications of UAV-RSPs for crop phenotyping. PMID:28713402

Multiple spectator condensates from inflation

NASA Astrophysics Data System (ADS)

Hardwick, Robert J.

2018-05-01

We investigate the development of spectator (light test) field condensates due to their quantum fluctuations in a de Sitter inflationary background, making use of the stochastic formalism to describe the system. In this context, a condensate refers to the typical field value found after a coarse-graining using the Hubble scale H, which can be essential to seed the initial conditions required by various post-inflationary processes. We study models with multiple coupled spectators and for the first time we demonstrate that new forms of stationary solution exist (distinct from the standard exponential form) when the potential is asymmetric. Furthermore, we find a critical value for the inter-field coupling as a function of the number of fields above which the formation of stationary condensates collapses to H. Considering some simple two-field example potentials, we are also able to derive a lower limit on the coupling, below which the fluctuations are effectively decoupled, and the standard stationary variance formulae for each field separately can be trusted. These results are all numerically verified by a new publicly available python class (nfield) to solve the coupled Langevin equations over a large number of fields, realisations and timescales. Further applications of this new tool are also discussed.

Independent validation of Swarm Level 2 magnetic field products and `Quick Look' for Level 1b data

NASA Astrophysics Data System (ADS)

Beggan, Ciarán D.; Macmillan, Susan; Hamilton, Brian; Thomson, Alan W. P.

2013-11-01

Magnetic field models are produced on behalf of the European Space Agency (ESA) by an independent scientific consortium known as the Swarm Satellite Constellation Application and Research Facility (SCARF), through the Level 2 Processor (L2PS). The consortium primarily produces magnetic field models for the core, lithosphere, ionosphere and magnetosphere. Typically, for each magnetic product, two magnetic field models are produced in separate chains using complementary data selection and processing techniques. Hence, the magnetic field models from the complementary processing chains will be similar but not identical. The final step in the overall L2PS therefore involves inspection and validation of the magnetic field models against each other and against data from (semi-) independent sources (e.g. ground observatories). We describe the validation steps for each magnetic field product and the comparison against independent datasets, and we show examples of the output of the validation. In addition, the L2PS also produces a daily set of `Quick Look' output graphics and statistics to monitor the overall quality of Level 1b data issued by ESA. We describe the outputs of the `Quick Look' chain.

Sound-field reproduction in-room using optimal control techniques: simulations in the frequency domain.

PubMed

Gauthier, Philippe-Aubert; Berry, Alain; Woszczyk, Wieslaw

2005-02-01

This paper describes the simulations and results obtained when applying optimal control to progressive sound-field reproduction (mainly for audio applications) over an area using multiple monopole loudspeakers. The model simulates a reproduction system that operates either in free field or in a closed space approaching a typical listening room, and is based on optimal control in the frequency domain. This rather simple approach is chosen for the purpose of physical investigation, especially in terms of sensing microphones and reproduction loudspeakers configurations. Other issues of interest concern the comparison with wave-field synthesis and the control mechanisms. The results suggest that in-room reproduction of sound field using active control can be achieved with a residual normalized squared error significantly lower than open-loop wave-field synthesis in the same situation. Active reproduction techniques have the advantage of automatically compensating for the room's natural dynamics. For the considered cases, the simulations show that optimal control results are not sensitive (in terms of reproduction error) to wall absorption in the reproduction room. A special surrounding configuration of sensors is introduced for a sensor-free listening area in free field.

Maximum a posteriori resampling of noisy, spatially correlated data

NASA Astrophysics Data System (ADS)

Goff, John A.; Jenkins, Chris; Calder, Brian

2006-08-01

In any geologic application, noisy data are sources of consternation for researchers, inhibiting interpretability and marring images with unsightly and unrealistic artifacts. Filtering is the typical solution to dealing with noisy data. However, filtering commonly suffers from ad hoc (i.e., uncalibrated, ungoverned) application. We present here an alternative to filtering: a newly developed method for correcting noise in data by finding the "best" value given available information. The motivating rationale is that data points that are close to each other in space cannot differ by "too much," where "too much" is governed by the field covariance. Data with large uncertainties will frequently violate this condition and therefore ought to be corrected, or "resampled." Our solution for resampling is determined by the maximum of the a posteriori density function defined by the intersection of (1) the data error probability density function (pdf) and (2) the conditional pdf, determined by the geostatistical kriging algorithm applied to proximal data values. A maximum a posteriori solution can be computed sequentially going through all the data, but the solution depends on the order in which the data are examined. We approximate the global a posteriori solution by randomizing this order and taking the average. A test with a synthetic data set sampled from a known field demonstrates quantitatively and qualitatively the improvement provided by the maximum a posteriori resampling algorithm. The method is also applied to three marine geology/geophysics data examples, demonstrating the viability of the method for diverse applications: (1) three generations of bathymetric data on the New Jersey shelf with disparate data uncertainties; (2) mean grain size data from the Adriatic Sea, which is a combination of both analytic (low uncertainty) and word-based (higher uncertainty) sources; and (3) side-scan backscatter data from the Martha's Vineyard Coastal Observatory which are, as is typical for such data, affected by speckle noise. Compared to filtering, maximum a posteriori resampling provides an objective and optimal method for reducing noise, and better preservation of the statistical properties of the sampled field. The primary disadvantage is that maximum a posteriori resampling is a computationally expensive procedure.

Development of a micro nuclear magnetic resonance system

NASA Astrophysics Data System (ADS)

Goloshevsky, Artem

Application of Nuclear Magnetic Resonance (NMR) to on-line/in-line control of industrial processes is currently limited by equipment costs and requirements for installation. A superconducting magnet generating strong fields is the most expensive part of a typical NMR instrument. In industrial environments, fringe magnetic fields make accommodation of NMR instruments difficult. However, a portable, low-cost and low-field magnetic resonance system can be used in virtually any environment. Development of a number of hardware components for a portable, low-cost NMR instrument is reported in this dissertation. Chapter one provides a discussion on a miniaturized Helmholtz spiral radio-frequency (RF) coil (average diameter equal to 3.5 mm) and an NMR probe built around a capillary (outer diameter = 1.59 mm and inner diameter = 1.02 mm) for flow imaging. Experiments of NMR spectroscopy, static and dynamic (flow) imaging, conducted with the use of the miniaturized coil, are described. Chapter two presents a microfabricated package of two biaxial gradient coils and a Helmholtz RF coil. Planar configuration of discrete wires was used to create magnetic field gradients. Performance of the microfabricated gradient coils while imaging water flow compared well with a commercial gradient set of much larger size. Chapter three reports on flow imaging experiments with power law fluids (aqueous solutions of sodium salt of carboxymethyl cellulose (CMC)) of different viscosities, carried out in the NMR probe with the miniaturized RF coil and capillary. Viscosities of the CMC solutions were determined based on the curve fits of the velocity profiles and simultaneous measurements of the flow rates. The curve fits were carried out according to the power law model equations. The NMR viscosity measurements compared well with measurements of the same CMC samples, performed on a conventional rotational rheometer. A portable, home-built transceiver, designed for NMR applications utilizing a miniaturized RF coil, is described in chapter four. The maximum RF power, occurring in the transceiver, was 21.5 dBm. Two transistor-transistor logic (TTL) switches functioned as an active duplexer. A quadrature detection scheme was used. The transceiver, combined with a filter/amplifier module, data acquisition (DAQ and RF generating PC boards, was successfully tested in NMR spectroscopy experiments at low magnetic field. It was demonstrated that, starting with the RF probe, a typical, large size NMR instrument can be miniaturized without impairment to the quality of the data. Such an instrument will be readily used in many industrial process control applications (e.g. for analysis of material properties and identification of chemicals).

A FPGA implementation for linearly unmixing a hyperspectral image using OpenCL

NASA Astrophysics Data System (ADS)

Guerra, Raúl; López, Sebastián.; Sarmiento, Roberto

2017-10-01

Hyperspectral imaging systems provide images in which single pixels have information from across the electromagnetic spectrum of the scene under analysis. These systems divide the spectrum into many contiguos channels, which may be even out of the visible part of the spectra. The main advantage of the hyperspectral imaging technology is that certain objects leave unique fingerprints in the electromagnetic spectrum, known as spectral signatures, which allow to distinguish between different materials that may look like the same in a traditional RGB image. Accordingly, the most important hyperspectral imaging applications are related with distinguishing or identifying materials in a particular scene. In hyperspectral imaging applications under real-time constraints, the huge amount of information provided by the hyperspectral sensors has to be rapidly processed and analysed. For such purpose, parallel hardware devices, such as Field Programmable Gate Arrays (FPGAs) are typically used. However, developing hardware applications typically requires expertise in the specific targeted device, as well as in the tools and methodologies which can be used to perform the implementation of the desired algorithms in the specific device. In this scenario, the Open Computing Language (OpenCL) emerges as a very interesting solution in which a single high-level synthesis design language can be used to efficiently develop applications in multiple and different hardware devices. In this work, the Fast Algorithm for Linearly Unmixing Hyperspectral Images (FUN) has been implemented into a Bitware Stratix V Altera FPGA using OpenCL. The obtained results demonstrate the suitability of OpenCL as a viable design methodology for quickly creating efficient FPGAs designs for real-time hyperspectral imaging applications.

DGSA: A Matlab toolbox for distance-based generalized sensitivity analysis of geoscientific computer experiments

NASA Astrophysics Data System (ADS)

Park, Jihoon; Yang, Guang; Satija, Addy; Scheidt, Céline; Caers, Jef

2016-12-01

Sensitivity analysis plays an important role in geoscientific computer experiments, whether for forecasting, data assimilation or model calibration. In this paper we focus on an extension of a method of regionalized sensitivity analysis (RSA) to applications typical in the Earth Sciences. Such applications involve the building of large complex spatial models, the application of computationally extensive forward modeling codes and the integration of heterogeneous sources of model uncertainty. The aim of this paper is to be practical: 1) provide a Matlab code, 2) provide novel visualization methods to aid users in getting a better understanding in the sensitivity 3) provide a method based on kernel principal component analysis (KPCA) and self-organizing maps (SOM) to account for spatial uncertainty typical in Earth Science applications and 4) provide an illustration on a real field case where the above mentioned complexities present themselves. We present methods that extend the original RSA method in several ways. First we present the calculation of conditional effects, defined as the sensitivity of a parameter given a level of another parameters. Second, we show how this conditional effect can be used to choose nominal values or ranges to fix insensitive parameters aiming to minimally affect uncertainty in the response. Third, we develop a method based on KPCA and SOM to assign a rank to spatial models in order to calculate the sensitivity on spatial variability in the models. A large oil/gas reservoir case is used as illustration of these ideas.

Performance of new 400-MHz HTS power-driven magnet NMR technology on typical pharmaceutical API, cinacalcet HCl.

PubMed

Silva Elipe, Maria Victoria; Donovan, Neil; Krull, Robert; Pooke, Donald; Colson, Kimberly L

2018-04-17

After years towards higher field strength magnets, nuclear magnetic resonance (NMR) technology in commercial instruments in the past decade has expanded at low and high magnetic fields to take advantage of new opportunities. At lower field strengths, permanent magnets are well established, whereas for midrange and high field, developments utilize superconducting magnets cooled with cryogenic liquids. Recently, the desire to locate NMR spectrometers in nontypical NMR laboratories has created interest in the development of cryogen-free magnets. These magnets require no cryogenic maintenance, eliminating routine filling and large cryogen dewars in the facility. Risks of spontaneous quenches and safety concerns when working with cryogenic liquids are eliminated. The highest field commercially available cryogen-free NMR magnet previously reported was at 4.7 T in 2013. Here we tested a prototype cryogen-free 9.4-T power-driven high-temperature-superconducting (HTS) magnet mated to commercial NMR spectrometer electronics. We chose cinacalcet HCl, a typical active pharmaceutical ingredient, to evaluate its performance towards structure elucidation. Satisfactory standard 1D and 2D homonuclear and heteronuclear NMR results were obtained and compared with those from a standard 9.4-T cryogenically cooled superconducting NMR instrument. The results were similar between both systems with minor differences. Further comparison with different shims and probes in the HTS magnet system confirmed that the magnet homogeneity profile could be matched with commercially available NMR equipment for optimal results. We conclude that HTS magnet technology works well providing results comparable with those of standard instruments, leading us to investigate additional applications for this magnet technology outside a traditional NMR facility. Copyright © 2018 John Wiley & Sons, Ltd.

Electrospray ionization from nanopipette emitters with tip diameters of less than 100 nm.

PubMed

Yuill, Elizabeth M; Sa, Niya; Ray, Steven J; Hieftje, Gary M; Baker, Lane A

2013-09-17

Work presented here demonstrates application of nanopipettes pulled to orifice diameters of less than 100 nm as electrospray ionization emitters for mass spectrometry. Mass spectrometric analysis of a series of peptides and proteins electrosprayed from pulled-quartz capillary nanopipette emitters with internal diameters ranging from 37 to 70 nm is detailed. Overall, the use of nanopipette emitters causes a shift toward the production of ions of higher charge states and leads to a reduction in width of charge-state distribution as compared to typical nanospray conditions. Further, nanopipettes show improved S/N and the same signal precision as typical nanospray, despite the much smaller dimensions. As characterized by SEM images acquired before and after spray, nanopipettes are shown to be robust under conditions employed. Analytical calculations and numerical simulations are used to calculate the electric field at the emitter tip, which can be significant for the small diameter tips used.

Hardware Architecture Study for NASA's Space Software Defined Radios

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.; Scardelletti, Maximilian C.; Mortensen, Dale J.; Kacpura, Thomas J.; Andro, Monty; Smith, Carl; Liebetreu, John

2008-01-01

This study defines a hardware architecture approach for software defined radios to enable commonality among NASA space missions. The architecture accommodates a range of reconfigurable processing technologies including general purpose processors, digital signal processors, field programmable gate arrays (FPGAs), and application-specific integrated circuits (ASICs) in addition to flexible and tunable radio frequency (RF) front-ends to satisfy varying mission requirements. The hardware architecture consists of modules, radio functions, and and interfaces. The modules are a logical division of common radio functions that comprise a typical communication radio. This paper describes the architecture details, module definitions, and the typical functions on each module as well as the module interfaces. Trade-offs between component-based, custom architecture and a functional-based, open architecture are described. The architecture does not specify the internal physical implementation within each module, nor does the architecture mandate the standards or ratings of the hardware used to construct the radios.

Space Telecommunications Radio Systems (STRS) Hardware Architecture Standard: Release 1.0 Hardware Section

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.; Kacpura, Thomas J.; Smith, Carl R.; Liebetreu, John; Hill, Gary; Mortensen, Dale J.; Andro, Monty; Scardelletti, Maximilian C.; Farrington, Allen

2008-01-01

This report defines a hardware architecture approach for software-defined radios to enable commonality among NASA space missions. The architecture accommodates a range of reconfigurable processing technologies including general-purpose processors, digital signal processors, field programmable gate arrays, and application-specific integrated circuits (ASICs) in addition to flexible and tunable radiofrequency front ends to satisfy varying mission requirements. The hardware architecture consists of modules, radio functions, and interfaces. The modules are a logical division of common radio functions that compose a typical communication radio. This report describes the architecture details, the module definitions, the typical functions on each module, and the module interfaces. Tradeoffs between component-based, custom architecture and a functional-based, open architecture are described. The architecture does not specify a physical implementation internally on each module, nor does the architecture mandate the standards or ratings of the hardware used to construct the radios.

From empirical data to time-inhomogeneous continuous Markov processes.

PubMed

Lencastre, Pedro; Raischel, Frank; Rogers, Tim; Lind, Pedro G

2016-03-01

We present an approach for testing for the existence of continuous generators of discrete stochastic transition matrices. Typically, existing methods to ascertain the existence of continuous Markov processes are based on the assumption that only time-homogeneous generators exist. Here a systematic extension to time inhomogeneity is presented, based on new mathematical propositions incorporating necessary and sufficient conditions, which are then implemented computationally and applied to numerical data. A discussion concerning the bridging between rigorous mathematical results on the existence of generators to its computational implementation is presented. Our detection algorithm shows to be effective in more than 60% of tested matrices, typically 80% to 90%, and for those an estimate of the (nonhomogeneous) generator matrix follows. We also solve the embedding problem analytically for the particular case of three-dimensional circulant matrices. Finally, a discussion of possible applications of our framework to problems in different fields is briefly addressed.

SU-E-T-611: Effective Treatment Volume of the Small Size IORT Applicators

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

Krechetov, A.S.; ASK Physics, Mountain View, CA; Goer, D.A.

2014-06-01

Purpose Mobile electron linear accelerators are gaining more attention recently, providing a lower cost and simpler way to perform intraoperative treatment. However, the simplicity of the treatment process does not eliminate the need for proper attention to the technical aspects of the treatment. One of the potential pitfalls is incorrect selection of the appropriate applicator size to adequately cover the tumor bed to the prescription dose. When treating tumor beds in the pelvis, the largest applicator that fits into the pelvis is usually selected as there is concern about microscopic extension of the disease along the sidewalls of the pelvis.more » But when treating early stage breast tumors, there is a natural tendency to select an applicator as small as possible so as not to jeopardize cosmesis. Methods This investigation questions how much of the typical breast treatment volume gets adequate exposure and what is the correct strategy in selecting the proper applicator size. Actual data from isodose scans were analyzed. Results We found that typical treatment dose prescriptions can cover as much as 80% and as little as 20% of the nominal treatment volume depending on the applicator size and energy of the beam and whether the dose is prescribed to the 80 or 90% isodose level. Treatment volume is defined as a cylinder with diameter equal to applicator and height equal to the corresponding D80 or D90 depth. Conclusion If mobile linear accelerators are used, there can be significant amount of “cold volume” depending on the applicator size and this should be taken into account when selecting the applicator that is needed. Using too small of an applicator could result in significant under-dosing to the tissue at risk. Long-term clinical data demonstrates that selecting an adequate field size results in good ontological control as well as excellent cosmesis. Intraop Medical Corp was providing facilities and equipment for this research.« less

A generalized sound extrapolation method for turbulent flows

NASA Astrophysics Data System (ADS)

Zhong, Siyang; Zhang, Xin

2018-02-01

Sound extrapolation methods are often used to compute acoustic far-field directivities using near-field flow data in aeroacoustics applications. The results may be erroneous if the volume integrals are neglected (to save computational cost), while non-acoustic fluctuations are collected on the integration surfaces. In this work, we develop a new sound extrapolation method based on an acoustic analogy using Taylor's hypothesis (Taylor 1938 Proc. R. Soc. Lon. A 164, 476-490. (doi:10.1098/rspa.1938.0032)). Typically, a convection operator is used to filter out the acoustically inefficient components in the turbulent flows, and an acoustics dominant indirect variable Dcp‧ is solved. The sound pressure p' at the far field is computed from Dcp‧ based on the asymptotic properties of the Green's function. Validations results for benchmark problems with well-defined sources match well with the exact solutions. For aeroacoustics applications: the sound predictions by the aerofoil-gust interaction are close to those by an earlier method specially developed to remove the effect of vortical fluctuations (Zhong & Zhang 2017 J. Fluid Mech. 820, 424-450. (doi:10.1017/jfm.2017.219)); for the case of vortex shedding noise from a cylinder, the off-body predictions by the proposed method match well with the on-body Ffowcs-Williams and Hawkings result; different integration surfaces yield close predictions (of both spectra and far-field directivities) for a co-flowing jet case using an established direct numerical simulation database. The results suggest that the method may be a potential candidate for sound projection in aeroacoustics applications.

Conductivity of molten sodium chloride in an arbitrarily weak dc electric field.

PubMed

Delhommelle, Jerome; Cummings, Peter T; Petravic, Janka

2005-09-15

We use nonequilibrium molecular-dynamics (NEMD) simulations to characterize the response of a fluid subjected to an electric field. We focus on the response for very weak fields. Fields accessible by conventional NEMD methods are typically of the order of 10(9) V m(-1), i.e., several orders of magnitude larger than those typically used in experiments. Using the transient time-correlation function, we show how NEMD simulations can be extended to study systems subjected to a realistic dc electric field. We then apply this approach to study the response of molten sodium chloride for a wide range of dc electric fields.

An on/off Berry phase switch in circular graphene resonators

NASA Astrophysics Data System (ADS)

Ghahari, Fereshte; Walkup, Daniel; Gutiérrez, Christopher; Rodriguez-Nieva, Joaquin F.; Zhao, Yue; Wyrick, Jonathan; Natterer, Fabian D.; Cullen, William G.; Watanabe, Kenji; Taniguchi, Takashi; Levitov, Leonid S.; Zhitenev, Nikolai B.; Stroscio, Joseph A.

2017-05-01

The phase of a quantum state may not return to its original value after the system’s parameters cycle around a closed path; instead, the wave function may acquire a measurable phase difference called the Berry phase. Berry phases typically have been accessed through interference experiments. Here, we demonstrate an unusual Berry phase-induced spectroscopic feature: a sudden and large increase in the energy of angular-momentum states in circular graphene p-n junction resonators when a relatively small critical magnetic field is reached. This behavior results from turning on a π Berry phase associated with the topological properties of Dirac fermions in graphene. The Berry phase can be switched on and off with small magnetic field changes on the order of 10 millitesla, potentially enabling a variety of optoelectronic graphene device applications.

Electrically reversible cracks in an intermetallic film controlled by an electric field

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

Liu, Z. Q.; Liu, J. H.; Biegalski, M. D.

Cracks in solid-state materials are typically irreversible. We report electrically reversible opening and closing of nanoscale cracks in an intermetallic thin film grown on a ferroelectric substrate driven by a small electric field (~0.83 kV/cm). Accordingly, a nonvolatile colossal electroresistance on-off ratio of more than 10 8 is measured across the cracks in the intermetallic film at room temperature. Cracks are easily formed with low-frequency voltage cycling and remain stable when the device is operated at high frequency, which offers intriguing potential for next-generation high-frequency memory applications. Moreover, endurance testing demonstrates that the opening and closing of such cracks canmore » reach over 10 7 cycles under 10-μs pulses, without catastrophic failure of the film.« less

Electrically reversible cracks in an intermetallic film controlled by an electric field

DOE PAGES

Liu, Z. Q.; Liu, J. H.; Biegalski, M. D.; ...

2018-01-03

Cracks in solid-state materials are typically irreversible. We report electrically reversible opening and closing of nanoscale cracks in an intermetallic thin film grown on a ferroelectric substrate driven by a small electric field (~0.83 kV/cm). Accordingly, a nonvolatile colossal electroresistance on-off ratio of more than 10 8 is measured across the cracks in the intermetallic film at room temperature. Cracks are easily formed with low-frequency voltage cycling and remain stable when the device is operated at high frequency, which offers intriguing potential for next-generation high-frequency memory applications. Moreover, endurance testing demonstrates that the opening and closing of such cracks canmore » reach over 10 7 cycles under 10-μs pulses, without catastrophic failure of the film.« less

Anomalous electronic structure and magnetoresistance in TaAs2

NASA Astrophysics Data System (ADS)

Luo, Yongkang; McDonald, R. D.; Rosa, P. F. S.; Scott, B.; Wakeham, N.; Ghimire, N. J.; Bauer, E. D.; Thompson, J. D.; Ronning, F.

2016-06-01

The change in resistance of a material in a magnetic field reflects its electronic state. In metals with weakly- or non-interacting electrons, the resistance typically increases upon the application of a magnetic field. In contrast, negative magnetoresistance may appear under some circumstances, e.g., in metals with anisotropic Fermi surfaces or with spin-disorder scattering and semimetals with Dirac or Weyl electronic structures. Here we show that the non-magnetic semimetal TaAs2 possesses a very large negative magnetoresistance, with an unknown scattering mechanism. Density functional calculations find that TaAs2 is a new topological semimetal [ℤ2 invariant (0;111)] without Dirac dispersion, demonstrating that a negative magnetoresistance in non-magnetic semimetals cannot be attributed uniquely to the Adler-Bell-Jackiw chiral anomaly of bulk Dirac/Weyl fermions.

Anomalous electronic structure and magnetoresistance in TaAs2

PubMed Central

Luo, Yongkang; McDonald, R. D.; Rosa, P. F. S.; Scott, B.; Wakeham, N.; Ghimire, N. J.; Bauer, E. D.; Thompson, J. D.; Ronning, F.

2016-01-01

The change in resistance of a material in a magnetic field reflects its electronic state. In metals with weakly- or non-interacting electrons, the resistance typically increases upon the application of a magnetic field. In contrast, negative magnetoresistance may appear under some circumstances, e.g., in metals with anisotropic Fermi surfaces or with spin-disorder scattering and semimetals with Dirac or Weyl electronic structures. Here we show that the non-magnetic semimetal TaAs2 possesses a very large negative magnetoresistance, with an unknown scattering mechanism. Density functional calculations find that TaAs2 is a new topological semimetal [ℤ2 invariant (0;111)] without Dirac dispersion, demonstrating that a negative magnetoresistance in non-magnetic semimetals cannot be attributed uniquely to the Adler-Bell-Jackiw chiral anomaly of bulk Dirac/Weyl fermions. PMID:27271852

Resonant fluorescence for multilevel systems in intense nonmonochromatic fields: possibilities for applications in laser medicine

NASA Astrophysics Data System (ADS)

Karagodova, Tamara Y.

1999-03-01

The theory of resonant fluorescence of multilevel system in two monochromatic intense laser fields has been applied for investigating the temporal decay of magnetic sublevels of an atom. As for two-level system the triplet of resonant fluorescence is observed, for real atom being the multilevel system the multiplet of resonant fluorescence can be observed. The excitation spectra, defining the intensities of lines in the multiplet of resonant fluorescence, and shifts of components of spectra are shown. Typical temporal dependence of fluorescence intensity for magnetic sublevels of an atom having different relaxation constants is shown. The computer simulation of resonant fluorescence for simple systems can help to understand the regularities in temporal decay curves of atherosclerotic plaque, malignant tumor compared to normal surrounding tissue.

Label-free electrical detection of pyrophosphate generated from DNA polymerase reactions on field-effect devices.

PubMed

Credo, Grace M; Su, Xing; Wu, Kai; Elibol, Oguz H; Liu, David J; Reddy, Bobby; Tsai, Ta-Wei; Dorvel, Brian R; Daniels, Jonathan S; Bashir, Rashid; Varma, Madoo

2012-03-21

We introduce a label-free approach for sensing polymerase reactions on deoxyribonucleic acid (DNA) using a chelator-modified silicon-on-insulator field-effect transistor (SOI-FET) that exhibits selective and reversible electrical response to pyrophosphate anions. The chemical modification of the sensor surface was designed to include rolling-circle amplification (RCA) DNA colonies for locally enhanced pyrophosphate (PPi) signal generation and sensors with immobilized chelators for capture and surface-sensitive detection of diffusible reaction by-products. While detecting arrays of enzymatic base incorporation reactions is typically accomplished using optical fluorescence or chemiluminescence techniques, our results suggest that it is possible to develop scalable and portable PPi-specific sensors and platforms for broad biomedical applications such as DNA sequencing and microbe detection using surface-sensitive electrical readout techniques.

Pristine Metal-Organic Frameworks and their Composites for Energy Storage and Conversion.

PubMed

Liang, Zibin; Qu, Chong; Guo, Wenhan; Zou, Ruqiang; Xu, Qiang

2017-11-22

Metal-organic frameworks (MOFs), a new class of crystalline porous organic-inorganic hybrid materials, have recently attracted increasing interest in the field of energy storage and conversion. Herein, recent progress of MOFs and MOF composites for energy storage and conversion applications, including photochemical and electrochemical fuel production (hydrogen production and CO 2 reduction), water oxidation, supercapacitors, and Li-based batteries (Li-ion, Li-S, and Li-O 2 batteries), is summarized. Typical development strategies (e.g., incorporation of active components, design of smart morphologies, and judicious selection of organic linkers and metal nodes) of MOFs and MOF composites for particular energy storage and conversion applications are highlighted. A broad overview of recent progress is provided, which will hopefully promote the future development of MOFs and MOF composites for advanced energy storage and conversion applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

FBCOT: a fast block coding option for JPEG 2000

NASA Astrophysics Data System (ADS)

Taubman, David; Naman, Aous; Mathew, Reji

2017-09-01

Based on the EBCOT algorithm, JPEG 2000 finds application in many fields, including high performance scientific, geospatial and video coding applications. Beyond digital cinema, JPEG 2000 is also attractive for low-latency video communications. The main obstacle for some of these applications is the relatively high computational complexity of the block coder, especially at high bit-rates. This paper proposes a drop-in replacement for the JPEG 2000 block coding algorithm, achieving much higher encoding and decoding throughputs, with only modest loss in coding efficiency (typically < 0.5dB). The algorithm provides only limited quality/SNR scalability, but offers truly reversible transcoding to/from any standard JPEG 2000 block bit-stream. The proposed FAST block coder can be used with EBCOT's post-compression RD-optimization methodology, allowing a target compressed bit-rate to be achieved even at low latencies, leading to the name FBCOT (Fast Block Coding with Optimized Truncation).

Suppression and nonlinear excitation of parasitic modes in second harmonic gyrotrons operating in a very high order mode

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

Nusinovich, Gregory S.; Pu, Ruifeng; Granatstein, Victor L.

2015-07-06

In recent years, there was an active development of high-power, sub-terahertz (sub-THz) gyrotrons for numerous applications. For example, a 0.67 THz gyrotron delivering more than 200 kW with about 20% efficiency was developed. This record high efficiency was achieved because the gyrotron operated in a high-order TE{sub 31,8}-mode with the power of ohmic losses less than 10% of the power of outgoing radiation. That gyrotron operated at the fundamental cyclotron resonance, and a high magnetic field of about 27 T was created by a pulse solenoid. For numerous applications, it is beneficial to use gyrotrons at cyclotron harmonics which can operate inmore » available cryomagnets with fields not exceeding 15 T. However, typically, the gyrotron operation at harmonics faces severe competition from parasitic modes at the fundamental resonance. In the present paper, we consider a similar 0.67 THz gyrotron designed for operation in the same TE{sub 31,8}-mode, but at the second harmonic. We focus on two nonlinear effects typical for interaction between the fundamental and second harmonic modes, viz., the mode suppression and the nonlinear excitation of the mode at the fundamental harmonic by the second harmonic oscillations. Our study includes both the analytical theory and numerical simulations performed with the self-consistent code MAGY. The simulations show that stable second harmonic operation in the TE{sub 31,8} mode is possible with only modest sacrifice of efficiency and power.« less

Retrieving Storm Electric Fields from Aircrfaft Field Mill Data: Part II: Applications

NASA Technical Reports Server (NTRS)

Koshak, William; Mach, D. M.; Christian H. J.; Stewart, M. F.; Bateman M. G.

2006-01-01

The Lagrange multiplier theory developed in Part I of this study is applied to complete a relative calibration of a Citation aircraft that is instrumented with six field mill sensors. When side constraints related to average fields are used, the Lagrange multiplier method performs well in computer simulations. For mill measurement errors of 1 V m(sup -1) and a 5 V m(sup -1) error in the mean fair-weather field function, the 3D storm electric field is retrieved to within an error of about 12%. A side constraint that involves estimating the detailed structure of the fair-weather field was also tested using computer simulations. For mill measurement errors of 1 V m(sup -l), the method retrieves the 3D storm field to within an error of about 8% if the fair-weather field estimate is typically within 1 V m(sup -1) of the true fair-weather field. Using this type of side constraint and data from fair-weather field maneuvers taken on 29 June 2001, the Citation aircraft was calibrated. Absolute calibration was completed using the pitch down method developed in Part I, and conventional analyses. The resulting calibration matrices were then used to retrieve storm electric fields during a Citation flight on 2 June 2001. The storm field results are encouraging and agree favorably in many respects with results derived from earlier (iterative) techniques of calibration.

Astrobiology Research Experience for Undergraduates: An Interdisciplinary REU Program at the SETI Institute

NASA Astrophysics Data System (ADS)

Phillips, C. B.; Devore, E. K.

2009-12-01

The SETI Institute hosts a summer Astrobiology Research Experience for Undergraduates program for highly motivated students interested in astrobiology research. Students work with scientists at the SETI Institute and at the nearby NASA Ames Research Center on projects spanning the field of astrobiology from microbiology to planetary geology to astronomy and astrophysics. Each student is mentored by a scientist for his/her summer research project. As astrobiology is interdisciplinary, the first week includes a seminar series to provide a broad foundation in the field as the students begin their research projects. The 10-week program includes a week-long field trip to the SETI Institute’s Allen Telescope Array, located at the Hat Creek Radio Astronomy Observatory in Northern California, as well as a field experience at hydrothermal systems at nearby Lassen Volcanic National Park. Students also participate in local field trips to places like the California Academy of Sciences and other nearby locations of scientific interest, and attend seminars, lectures, and discussions on astrobiology. Students are also invited to attend events at nearby NASA Ames Research Center, which offers the opportunity to interact with other undergraduate and graduate students participating in NASA summer programs. At the end of the program, students write up and present their research projects, and mentors recommend some projects for submission to a national scientific conference, which the selected students will be funded to attend. The Astrobiology REU program emphasizes three main areas, which are listed in the table along with typical project themes. Each year, specific student research projects are described on the website, and students are asked to select the three that most interest them as a part of their applications. Applications are due in early February. Typically, 10 students apply for each available position. Students have been selected from colleges and universities national-wide, including community colleges. The Astrobiology REU program has served 4 classes of students, and is funded through summer of 2011. A total of 61 students have participated (12 in 2006, 17 in 2007, 17 in 2008, and 15 in 2009); all have successfully completed their internships. Of these students, 59% were women, and 21% were minorities. To date 18 students have gone on to graduate studies, in Master’s or PhD programs at schools including Harvard, UC Berkeley, UC Santa Cruz, Stanford, Univ. of Nebraska, and many others, in fields including astronomy, optical science, space life sciences, geology, physics, mechanical engineering, and molecular and cellular biology. The SETI Institute is a non-profit private scientific research institution located in California’s Silicon Valley. The Astrobiology REU program is supported by National Science Foundation Grant AST-0852095 with additional funding from NASA’s Astrobiology Institute, the SETI Institute and private donors.Main research areas and typical project themes

A photoelastic modulator-based birefringence imaging microscope for measuring biological specimens

NASA Astrophysics Data System (ADS)

Freudenthal, John; Leadbetter, Andy; Wolf, Jacob; Wang, Baoliang; Segal, Solomon

2014-11-01

The photoelastic modulator (PEM) has been applied to a variety of polarimetric measurements. However, nearly all such applications use point-measurements where each point (spot) on the sample is measured one at a time. The main challenge for employing the PEM in a camera-based imaging instrument is that the PEM modulates too fast for typical cameras. The PEM modulates at tens of KHz. To capture the specific polarization information that is carried on the modulation frequency of the PEM, the camera needs to be at least ten times faster. However, the typical frame rates of common cameras are only in the tens or hundreds frames per second. In this paper, we report a PEM-camera birefringence imaging microscope. We use the so-called stroboscopic illumination method to overcome the incompatibility of the high frequency of the PEM to the relatively slow frame rate of a camera. We trigger the LED light source using a field-programmable gate array (FPGA) in synchrony with the modulation of the PEM. We show the measurement results of several standard birefringent samples as a part of the instrument calibration. Furthermore, we show results observed in two birefringent biological specimens, a human skin tissue that contains collagen and a slice of mouse brain that contains bundles of myelinated axonal fibers. Novel applications of this PEM-based birefringence imaging microscope to both research communities and industrial applications are being tested.

High power microwave hazard facing smart ammunitions

NASA Astrophysics Data System (ADS)

Bohl, J.

1995-03-01

The battle field of the present and even more the one in future will be characterized by the use of weapon systems with a high degree of electronics, computers, and sensors, designed and built to keep not only the man out of the loop. But the higher the technology used for smart weapon systems, the more these systems are endangered by numerous sources of hazard. One of those sources is the threat caused by induced or natural electromagnetic fields. These threat factors can be generated by natural, civil and military environment. In principle there are two main applications which must be considered in military applications: Firstly, weapon systems, that is, high power microwave sources as well as intelligent electromagnetic radiation systems to defeat ammunition on the battle field and secondly, the hardening of the own smart ammunition systems and missiles against the interference sources created by the different types of electromagnetic fields. This report will discuss the possible electromagnetic coupling effects on smart ammunition and missiles and their typical interference caused on the electronics and sensor level. Real time 6-DOF simulations show the flight mission which may be compromised depending on the coupled electromagnetic fields. The German MOD has established a research program where smart ammunitions with different seeker systems are investigated in respect of the coupling effects on smart ammunition caused by high power microwaves. This program considers all available resources and know how in Germany. The systems are investigated by analytical, numerical, and experimental methods with passive and activated missiles.

Application of lab derived kinetic biodegradation parameters at the field scale

NASA Astrophysics Data System (ADS)

Schirmer, M.; Barker, J. F.; Butler, B. J.; Frind, E. O.

2003-04-01

Estimating the intrinsic remediation potential of an aquifer typically requires the accurate assessment of the biodegradation kinetics, the level of available electron acceptors and the flow field. Zero- and first-order degradation rates derived at the laboratory scale generally overpredict the rate of biodegradation when applied to the field scale, because limited electron acceptor availability and microbial growth are typically not considered. On the other hand, field estimated zero- and first-order rates are often not suitable to forecast plume development because they may be an oversimplification of the processes at the field scale and ignore several key processes, phenomena and characteristics of the aquifer. This study uses the numerical model BIO3D to link the laboratory and field scale by applying laboratory derived Monod kinetic degradation parameters to simulate a dissolved gasoline field experiment at Canadian Forces Base (CFB) Borden. All additional input parameters were derived from laboratory and field measurements or taken from the literature. The simulated results match the experimental results reasonably well without having to calibrate the model. An extensive sensitivity analysis was performed to estimate the influence of the most uncertain input parameters and to define the key controlling factors at the field scale. It is shown that the most uncertain input parameters have only a minor influence on the simulation results. Furthermore it is shown that the flow field, the amount of electron acceptor (oxygen) available and the Monod kinetic parameters have a significant influence on the simulated results. Under the field conditions modelled and the assumptions made for the simulations, it can be concluded that laboratory derived Monod kinetic parameters can adequately describe field scale degradation processes, if all controlling factors are incorporated in the field scale modelling that are not necessarily observed at the lab scale. In this way, there are no scale relationships to be found that link the laboratory and the field scale, accurately incorporating the additional processes, phenomena and characteristics, such as a) advective and dispersive transport of one or more contaminants, b) advective and dispersive transport and availability of electron acceptors, c) mass transfer limitations and d) spatial heterogeneities, at the larger scale and applying well defined lab scale parameters should accurately describe field scale processes.

Applications of nanotechnology in wastewater treatment--a review.

PubMed

Bora, Tanujjal; Dutta, Joydeep

2014-01-01

Water on Earth is a precious and finite resource, which is endlessly recycled in the water cycle. Water, whose physical, chemical, or biological properties have been altered due to the addition of contaminants such as organic/inorganic materials, pathogens, heavy metals or other toxins making it unsafe for the ecosystem, can be termed as wastewater. Various schemes have been adopted by industries across the world to treat wastewater prior to its release to the ecosystem, and several new concepts and technologies are fast replacing the traditional methods. This article briefly reviews the recent advances and application of nanotechnology for wastewater treatment. Nanomaterials typically have high reactivity and a high degree of functionalization, large specific surface area, size-dependent properties etc., which makes them suitable for applications in wastewater treatment and for water purification. In this article, the application of various nanomaterials such as metal nanoparticles, metal oxides, carbon compounds, zeolite, filtration membranes, etc., in the field of wastewater treatment is discussed.

IMS applications analysis

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

RODACY,PHILIP J.; REBER,STEPHEN D.; SIMONSON,ROBERT J.

This report examines the market potential of a miniature, hand-held Ion Mobility Spectrometer. Military and civilian markets are discussed, as well as applications in a variety of diverse fields. The strengths and weaknesses of competing technologies are discussed. An extensive Ion Mobility Spectrometry (IMS) bibliography is included. The conclusions drawn from this study are: (1) There are a number of competing technologies that are capable of detecting explosives, drugs, biological, or chemical agents. The IMS system currently represents the best available compromise regarding sensitivity, specificity, and portability. (2) The military market is not as large as the commercial market, butmore » the military services are more likely to invest R and D funds in the system. (3) Military applications should be addressed before commercial applications are addressed. (4) There is potentially a large commercial market for rugged, hand-held Ion Mobility Spectrometer systems. Commercial users typically do not invest R and D funds in this type of equipment rather, they wait for off-the-shelf availability.« less

Monte Carlo study of out-of-field exposure in carbon-ion radiotherapy with a passive beam: Organ doses in prostate cancer treatment.

PubMed

Yonai, Shunsuke; Matsufuji, Naruhiro; Akahane, Keiichi

2018-04-23

The aim of this work was to estimate typical dose equivalents to out-of-field organs during carbon-ion radiotherapy (CIRT) with a passive beam for prostate cancer treatment. Additionally, sensitivity analyses of organ doses for various beam parameters and phantom sizes were performed. Because the CIRT out-of-field dose depends on the beam parameters, the typical values of those parameters were determined from statistical data on the target properties of patients who received CIRT at the Heavy-Ion Medical Accelerator in Chiba (HIMAC). Using these typical beam-parameter values, out-of-field organ dose equivalents during CIRT for typical prostate treatment were estimated by Monte Carlo simulations using the Particle and Heavy-Ion Transport Code System (PHITS) and the ICRP reference phantom. The results showed that the dose decreased with distance from the target, ranging from 116 mSv in the testes to 7 mSv in the brain. The organ dose equivalents per treatment dose were lower than those either in 6-MV intensity-modulated radiotherapy or in brachytherapy with an Ir-192 source for organs within 40 cm of the target. Sensitivity analyses established that the differences from typical values were within ∼30% for all organs, except the sigmoid colon. The typical out-of-field organ dose equivalents during passive-beam CIRT were shown. The low sensitivity of the dose equivalent in organs farther than 20 cm from the target indicated that individual dose assessments required for retrospective epidemiological studies may be limited to organs around the target in cases of passive-beam CIRT for prostate cancer. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Supramolecular gel electrophoresis of large DNA fragments.

PubMed

Tazawa, Shohei; Kobayashi, Kazuhiro; Oyoshi, Takanori; Yamanaka, Masamichi

2017-10-01

Pulsed-field gel electrophoresis is a frequent technique used to separate exceptionally large DNA fragments. In a typical continuous field electrophoresis, it is challenging to separate DNA fragments larger than 20 kbp because they migrate at a comparable rate. To overcome this challenge, it is necessary to develop a novel matrix for the electrophoresis. Here, we describe the electrophoresis of large DNA fragments up to 166 kbp using a supramolecular gel matrix and a typical continuous field electrophoresis system. C 3 -symmetric tris-urea self-assembled into a supramolecular hydrogel in tris-boric acid-EDTA buffer, a typical buffer for DNA electrophoresis, and the supramolecular hydrogel was used as a matrix for electrophoresis to separate large DNA fragments. Three types of DNA marker, the λ-Hind III digest (2 to 23 kbp), Lambda DNA-Mono Cut Mix (10 to 49 kbp), and Marker 7 GT (10 to 165 kbp), were analyzed in this study. Large DNA fragments of greater than 100 kbp showed distinct mobility using a typical continuous field electrophoresis system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Time series analysis of contaminant transport in the subsurface: applications to conservative tracer and engineered nanomaterials.

PubMed

Bai, Chunmei; Li, Yusong

2014-08-01

Accurately predicting the transport of contaminants in the field is subject to multiple sources of uncertainty due to the variability of geological settings, the complexity of field measurements, and the scarcity of data. Such uncertainties can be amplified when modeling some emerging contaminants, such as engineered nanomaterials, when a fundamental understanding of their fate and transport is lacking. Typical field work includes collecting concentration at a certain location for an extended period of time, or measuring the movement of plume for an extended period time, which would result in a time series of observation data. This work presents an effort to evaluate the possibility of applying time series analysis, particularly, autoregressive integrated moving average (ARIMA) models, to forecast contaminant transport and distribution in the subsurface environment. ARIMA modeling was first assessed in terms of its capability to forecast tracer transport at two field sites, which had different levels of heterogeneity. After that, this study evaluated the applicability of ARIMA modeling to predict the transport of engineered nanomaterials at field sites, including field measured data of nanoscale zero valent iron and (nZVI) and numerically generated data for the transport of nano-fullerene aggregates (nC60). This proof-of-concept effort demonstrates the possibility of applying ARIMA to predict the contaminant transport in the subsurface environment. Like many other statistical models, ARIMA modeling is only descriptive and not explanatory. The limitation and the challenge associated with applying ARIMA modeling to contaminant transport in the subsurface are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Time series analysis of contaminant transport in the subsurface: Applications to conservative tracer and engineered nanomaterials

NASA Astrophysics Data System (ADS)

Bai, Chunmei; Li, Yusong

2014-08-01

Accurately predicting the transport of contaminants in the field is subject to multiple sources of uncertainty due to the variability of geological settings, the complexity of field measurements, and the scarcity of data. Such uncertainties can be amplified when modeling some emerging contaminants, such as engineered nanomaterials, when a fundamental understanding of their fate and transport is lacking. Typical field work includes collecting concentration at a certain location for an extended period of time, or measuring the movement of plume for an extended period time, which would result in a time series of observation data. This work presents an effort to evaluate the possibility of applying time series analysis, particularly, autoregressive integrated moving average (ARIMA) models, to forecast contaminant transport and distribution in the subsurface environment. ARIMA modeling was first assessed in terms of its capability to forecast tracer transport at two field sites, which had different levels of heterogeneity. After that, this study evaluated the applicability of ARIMA modeling to predict the transport of engineered nanomaterials at field sites, including field measured data of nanoscale zero valent iron and (nZVI) and numerically generated data for the transport of nano-fullerene aggregates (nC60). This proof-of-concept effort demonstrates the possibility of applying ARIMA to predict the contaminant transport in the subsurface environment. Like many other statistical models, ARIMA modeling is only descriptive and not explanatory. The limitation and the challenge associated with applying ARIMA modeling to contaminant transport in the subsurface are also discussed.

Field-Portable Pixel Super-Resolution Colour Microscope

PubMed Central

Greenbaum, Alon; Akbari, Najva; Feizi, Alborz; Luo, Wei; Ozcan, Aydogan

2013-01-01

Based on partially-coherent digital in-line holography, we report a field-portable microscope that can render lensfree colour images over a wide field-of-view of e.g., >20 mm2. This computational holographic microscope weighs less than 145 grams with dimensions smaller than 17×6×5 cm, making it especially suitable for field settings and point-of-care use. In this lensfree imaging design, we merged a colorization algorithm with a source shifting based multi-height pixel super-resolution technique to mitigate ‘rainbow’ like colour artefacts that are typical in holographic imaging. This image processing scheme is based on transforming the colour components of an RGB image into YUV colour space, which separates colour information from brightness component of an image. The resolution of our super-resolution colour microscope was characterized using a USAF test chart to confirm sub-micron spatial resolution, even for reconstructions that employ multi-height phase recovery to handle dense and connected objects. To further demonstrate the performance of this colour microscope Papanicolaou (Pap) smears were also successfully imaged. This field-portable and wide-field computational colour microscope could be useful for tele-medicine applications in resource poor settings. PMID:24086742

Stratigraphic traps 3

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

Foster, N.H.; Beaumont, E.A.

1992-01-01

This book reports on the Treatise of Petroleum Geology was conceived during a discussion held at the annual AAPG meeting in 1984 in San Antonio, Texas. With input form the Advisory Board of the Treatise of Petroleum Geology, the authors designed this set of publications to represent, to the degree possible, the cutting edge in petroleum exploration knowledge and application: the Reprint Series to provide useful and important published literature; the Atlas to comprise a collection of detailed field studies that illustrate the many ways oil and gas are trapped and to serve as a guide to the petroleum geologymore » of basins where these fields are found; and the Handbook as a professional explorationist's guide to the latest knowledge in the various areas of petroleum geology and related disciplines. The treatise Atlas is part of AAPG's long tradition of publishing field studies. Notable AAPG field study complications include Structure of Typical American Fields, published in 1929 and edited by Sidney Powers; and Memoir 30, Giant Fields of 1968-1978, published in 1981 and edited by Michel T. Halbouty. The Treatise Atlas continues that tradition but introduces a format designed for easier access to data.« less

Quasi-Static Magnetic Field Shielding Using Longitudinal Mu-Near-Zero Metamaterials.

PubMed

Lipworth, Guy; Ensworth, Joshua; Seetharam, Kushal; Lee, Jae Seung; Schmalenberg, Paul; Nomura, Tsuyoshi; Reynolds, Matthew S; Smith, David R; Urzhumov, Yaroslav

2015-08-03

The control of quasi-static magnetic fields is of considerable interest in applications including the reduction of electromagnetic interference (EMI), wireless power transfer (WPT), and magnetic resonance imaging (MRI). The shielding of static or quasi-static magnetic fields is typically accomplished through the use of inherently magnetic materials with large magnetic permeability, such as ferrites, used sometimes in combination with metallic sheets and/or active field cancellation. Ferrite materials, however, can be expensive, heavy and brittle. Inspired by recent demonstrations of epsilon-, mu- and index-near-zero metamaterials, here we show how a longitudinal mu-near-zero (LMNZ) layer can serve as a strong frequency-selective reflector of magnetic fields when operating in the near-field region of dipole-like sources. Experimental measurements with a fabricated LMNZ sheet constructed from an artificial magnetic conductor - formed from non-magnetic, conducting, metamaterial elements - confirm that the artificial structure provides significantly improved shielding as compared with a commercially available ferrite of the same size. Furthermore, we design a structure to shield simultaneously at the fundamental and first harmonic frequencies. Such frequency-selective behavior can be potentially useful for shielding electromagnetic sources that may also generate higher order harmonics, while leaving the transmission of other frequencies unaffected.

ACTIVE REGION FILAMENTS MIGHT HARBOR WEAK MAGNETIC FIELDS

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

Díaz Baso, C. J.; Martínez González, M. J.; Asensio Ramos, A., E-mail: cdiazbas@iac.es

Recent spectropolarimetric observations of active region filaments have revealed polarization profiles with signatures typical of the strong field Zeeman regime. The conspicuous absence in those observations of scattering polarization and Hanle effect signatures was then pointed out by some authors. This was interpreted as either a signature of mixed “turbulent” field components or as a result of optical thickness. In this article, we present a natural scenario to explain these Zeeman-only spectropolarimetric observations of active region (AR) filaments. We propose a two-component model, one on top of the other. Both components have horizontal fields, with the azimuth difference between themmore » being close to 90°. The component that lies lower in the atmosphere is permeated by a strong field of the order of 600 G, while the upper component has much weaker fields, of the order of 10 G. The ensuing scattering polarization signatures of the individual components have opposite signs, so its combination along the line of sight reduces—and even can cancel out—the Hanle signatures, giving rise to an apparent Zeeman-only profile. This model is also applicable to other chromospheric structures seen in absorption above ARs.« less

Field-portable pixel super-resolution colour microscope.

PubMed

Greenbaum, Alon; Akbari, Najva; Feizi, Alborz; Luo, Wei; Ozcan, Aydogan

2013-01-01

Based on partially-coherent digital in-line holography, we report a field-portable microscope that can render lensfree colour images over a wide field-of-view of e.g., >20 mm(2). This computational holographic microscope weighs less than 145 grams with dimensions smaller than 17×6×5 cm, making it especially suitable for field settings and point-of-care use. In this lensfree imaging design, we merged a colorization algorithm with a source shifting based multi-height pixel super-resolution technique to mitigate 'rainbow' like colour artefacts that are typical in holographic imaging. This image processing scheme is based on transforming the colour components of an RGB image into YUV colour space, which separates colour information from brightness component of an image. The resolution of our super-resolution colour microscope was characterized using a USAF test chart to confirm sub-micron spatial resolution, even for reconstructions that employ multi-height phase recovery to handle dense and connected objects. To further demonstrate the performance of this colour microscope Papanicolaou (Pap) smears were also successfully imaged. This field-portable and wide-field computational colour microscope could be useful for tele-medicine applications in resource poor settings.

Agricultural crop harvest progress monitoring by fully polarimetric synthetic aperture radar imagery

NASA Astrophysics Data System (ADS)

Yang, Hao; Zhao, Chunjiang; Yang, Guijun; Li, Zengyuan; Chen, Erxue; Yuan, Lin; Yang, Xiaodong; Xu, Xingang

2015-01-01

Dynamic mapping and monitoring of crop harvest on a large spatial scale will provide critical information for the formulation of optimal harvesting strategies. This study evaluates the feasibility of C-band polarimetric synthetic aperture radar (PolSAR) for monitoring the harvesting progress of oilseed rape (Brassica napus L.) fields. Five multitemporal, quad-pol Radarsat-2 images and one optical ZY-1 02C image were acquired over a farmland area in China during the 2013 growing season. Typical polarimetric signatures were obtained relying on polarimetric decomposition methods. Temporal evolutions of these signatures of harvested fields were compared with the ones of unharvested fields in the context of the entire growing cycle. Significant sensitivity was observed between the specific polarimetric parameters and the harvest status of oilseed rape fields. Based on this sensitivity, a new method that integrates two polarimetric features was devised to detect the harvest status of oilseed rape fields using a single image. The validation results are encouraging even for the harvested fields covered with high residues. This research demonstrates the capability of PolSAR remote sensing in crop harvest monitoring, which is a step toward more complex applications of PolSAR data in precision agriculture.

Taxonomic and ad hoc categorization within the two cerebral hemispheres.

PubMed

Shen, Yeshayahu; Aharoni, Bat-El; Mashal, Nira

2015-01-01

A typicality effect refers to categorization which is performed more quickly or more accurately for typical than for atypical members of a given category. Previous studies reported a typicality effect for category members presented in the left visual field/right hemisphere (RH), suggesting that the RH applies a similarity-based categorization strategy. However, findings regarding the typicality effect within the left hemisphere (LH) are less conclusive. The current study tested the pattern of typicality effects within each hemisphere for both taxonomic and ad hoc categories, using words presented to the left or right visual fields. Experiment 1 tested typical and atypical members of taxonomic categories as well as non-members, and Experiment 2 tested typical and atypical members of ad hoc categories as well as non-members. The results revealed a typicality effect in both hemispheres and in both types of categories. Furthermore, the RH categorized atypical stimuli more accurately than did the LH. Our findings suggest that both hemispheres rely on a similarity-based categorization strategy, but the coarse semantic coding of the RH seems to facilitate the categorization of atypical members.

The formation of Cr2O3 nanoclusters over graphene sheet and carbon nanotubes

NASA Astrophysics Data System (ADS)

Dabaghmanesh, Samira; Neek-Amal, Mehdi; Partoens, Bart; Neyts, Erik C.

2017-11-01

Carbon supported metal oxide nanoparticles hold promise for various future applications in diverse areas including spintronics, catalysis and biomedicine. These applications, however, typically depend on the structure and morphology of the nanoparticles. In this contribution, we employ classical molecular dynamic simulations based on a recently developed force field to study the structural properties of Cr2O3 nanoclusters over graphene and carbon nanotubes. We observe that Cr2O3 nanoclusters tend to aggregate over both freestanding graphene and carbon nanotubes and form larger nanoclusters. These large nanoclusters are characterized by their worm-like shape with a lattice constant similar to that of bulk Cr2O3. We also investigate the structural deformation induced in graphene due to the presence of Cr2O3 nanoclusters.

Recent Progress in Technologies for Tactile Sensors

PubMed Central

Sun, Xuguang; Xue, Ning; Li, Tong; Liu, Chang

2018-01-01

Over the last two decades, considerable scientific and technological efforts have been devoted to developing tactile sensing based on a variety of transducing mechanisms, with prospective applications in many fields such as human–machine interaction, intelligent robot tactile control and feedback, and tactile sensorized minimally invasive surgery. This paper starts with an introduction of human tactile systems, followed by a presentation of the basic demands of tactile sensors. State-of-the-art tactile sensors are reviewed in terms of their diverse sensing mechanisms, design consideration, and material selection. Subsequently, typical performances of the sensors, along with their advantages and disadvantages, are compared and analyzed. Two major potential applications of tactile sensing systems are discussed in detail. Lastly, we propose prospective research directions and market trends of tactile sensing systems. PMID:29565835

The review of various synthesis methods of barium titanate with the enhanced dielectric properties

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

More, S. P., E-mail: smitalomte@gmail.com; Topare, R. J., E-mail: r-topare@yahoo.com

2016-05-06

The Barium Titanate is a very well known dielectric ceramic belongs to perovskite structure. It has very wide applications in the field of electronic, electro ceramic, electromechanical and electro-optical applications. Barium Titanate has very high dielectric constant as well as low dielectric loss. Substituted dielectrics are one of the most important technological compounds in modern electro ceramics. Its electrical properties can be tuned flexibly by a simple substitution technique. This has encouraged researchers to select a typical cation to be substituted at cationic sites. In the present paper, the review of various synthesis methods of Barium Titanate compound with themore » effect of different dopants, the grain size on the dielectric properties at various temperatures is discussed.« less

Segmentation of human brain using structural MRI.

PubMed

Helms, Gunther

2016-04-01

Segmentation of human brain using structural MRI is a key step of processing in imaging neuroscience. The methods have undergone a rapid development in the past two decades and are now widely available. This non-technical review aims at providing an overview and basic understanding of the most common software. Starting with the basis of structural MRI contrast in brain and imaging protocols, the concepts of voxel-based and surface-based segmentation are discussed. Special emphasis is given to the typical contrast features and morphological constraints of cortical and sub-cortical grey matter. In addition to the use for voxel-based morphometry, basic applications in quantitative MRI, cortical thickness estimations, and atrophy measurements as well as assignment of cortical regions and deep brain nuclei are briefly discussed. Finally, some fields for clinical applications are given.

Motion artifact removal in FNIR spectroscopy for real-world applications

NASA Astrophysics Data System (ADS)

Devaraj, Ajit; Izzetoglu, Meltem; Izzetoglu, Kurtulus; Bunce, Scott C.; Li, Connie Y.; Onaral, Banu

2004-12-01

Near infrared spectroscopy as a neuroimaging modality is a recent development. Near infrared neuroimagers are typically safe, portable, relatively affordable and non-invasive. The ease of sensor setup and non-intrusiveness make functional near infrared (fNIR) imaging an ideal candidate for monitoring human cortical function in a wide range of real world situations. However optical signals are susceptible to motion-artifacts, hindering the application of fNIR in studies where subject mobility cannot be controlled. In this paper, we present a filtering framework for motion-artifact cancellation to facilitate the deployment of fNIR imaging in real-world scenarios. We simulate a generic field environment by having subjects walk on a treadmill while performing a cognitive task and demonstrate that measurements can be effectively cleaned of motion-artifacts.

Recent Progress in Technologies for Tactile Sensors.

PubMed

Chi, Cheng; Sun, Xuguang; Xue, Ning; Li, Tong; Liu, Chang

2018-03-22

Over the last two decades, considerable scientific and technological efforts have been devoted to developing tactile sensing based on a variety of transducing mechanisms, with prospective applications in many fields such as human-machine interaction, intelligent robot tactile control and feedback, and tactile sensorized minimally invasive surgery. This paper starts with an introduction of human tactile systems, followed by a presentation of the basic demands of tactile sensors. State-of-the-art tactile sensors are reviewed in terms of their diverse sensing mechanisms, design consideration, and material selection. Subsequently, typical performances of the sensors, along with their advantages and disadvantages, are compared and analyzed. Two major potential applications of tactile sensing systems are discussed in detail. Lastly, we propose prospective research directions and market trends of tactile sensing systems.

Toward more versatile and intuitive cortical brain machine interfaces

PubMed Central

Andersen, Richard A.; Kellis, Spencer; Klaes, Christian; Aflalo, Tyson

2015-01-01

Brain machine interfaces have great potential in neuroprosthetic applications to assist patients with brain injury and neurodegenerative diseases. One type of BMI is a cortical motor prosthetic which is used to assist paralyzed subjects. Motor prosthetics to date have typically used the motor cortex as a source of neural signals for controlling external devices. The review will focus on several new topics in the arena of cortical prosthetics. These include using 1) recordings from cortical areas outside motor cortex; 2) local field potentials (LFPs) as a source of recorded signals; 3) somatosensory feedback for more dexterous control of robotics; and 4) new decoding methods that work in concert to form an ecology of decode algorithms. These new advances hold promise in greatly accelerating the applicability and ease of operation of motor prosthetics. PMID:25247368

Maximum likelihood resampling of noisy, spatially correlated data

NASA Astrophysics Data System (ADS)

Goff, J.; Jenkins, C.

2005-12-01

In any geologic application, noisy data are sources of consternation for researchers, inhibiting interpretability and marring images with unsightly and unrealistic artifacts. Filtering is the typical solution to dealing with noisy data. However, filtering commonly suffers from ad hoc (i.e., uncalibrated, ungoverned) application, which runs the risk of erasing high variability components of the field in addition to the noise components. We present here an alternative to filtering: a newly developed methodology for correcting noise in data by finding the "best" value given the data value, its uncertainty, and the data values and uncertainties at proximal locations. The motivating rationale is that data points that are close to each other in space cannot differ by "too much", where how much is "too much" is governed by the field correlation properties. Data with large uncertainties will frequently violate this condition, and in such cases need to be corrected, or "resampled." The best solution for resampling is determined by the maximum of the likelihood function defined by the intersection of two probability density functions (pdf): (1) the data pdf, with mean and variance determined by the data value and square uncertainty, respectively, and (2) the geostatistical pdf, whose mean and variance are determined by the kriging algorithm applied to proximal data values. A Monte Carlo sampling of the data probability space eliminates non-uniqueness, and weights the solution toward data values with lower uncertainties. A test with a synthetic data set sampled from a known field demonstrates quantitatively and qualitatively the improvement provided by the maximum likelihood resampling algorithm. The method is also applied to three marine geology/geophysics data examples: (1) three generations of bathymetric data on the New Jersey shelf with disparate data uncertainties; (2) mean grain size data from the Adriatic Sea, which is combination of both analytic (low uncertainty) and word-based (higher uncertainty) sources; and (3) sidescan backscatter data from the Martha's Vineyard Coastal Observatory which are, as is typical for such data, affected by speckly noise.

Re-Verification of the IRHN57133SE and IRHN57250SE for Single Event Gate Rupture and Single Event Burnout

NASA Technical Reports Server (NTRS)

Scheick, Leif

2010-01-01

The vertical metal oxide semiconductor field-effect transistor (MOSFET) is a widely used power transistor onboard a spacecraft. The MOSFET is typically employed in power supplies and high current switching applications. Due to the inherent high electric fields in the device, power MOSFETs are sensitive to heavy ion irradiation and can fail catastrophically as a result of single event gate rupture (SEGR) or single event burnout (SEB). Manufacturers have designed radiation-hardened power MOSFETs for space applications. These radiation hardened devices are not immune to SEGR or SEB but, rather, can exhibit them at a much more damaging ion than their non-radiation hardened counterparts. See [1] through [5] for more information.This effort was to investigate the SEGR and SEB responses of two power MOSFETs from IR(the IRHN57133SE and the IRHN57250SE) that have recently been produced on a new fabrication line. These tests will serve as a limited verification of these parts, but it is acknowledged that further testing on the respective parts may be needed for some mission profiles.

Using IR spectroscopy to determine biodiesel conversion

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

Tirla, Cornelia; Dooling, Thomas; Smith, Rachel B.

This project’s aim was to develop a way to use Infrared (IR) Spectroscopy to determine the extent of the conversion of oil to biodiesel produced during a typical transesterification process. The most reliable method of biodiesel analysis is gas chromatography with flame ionization detector (GC-FID) analysis. This analysis is not ideal for the educational or field applications since it is time intensive and requires expensive, specialized equipment. The use of the FT-IR is faster and more affordable. A calibration curve was created by comparing data on the purity of biodiesel samples obtained from the GC-FID analysis to the ratio ofmore » the absorbances at 1197 cm -1 to 1166 cm -1 from the FT-IR spectrum. For field application, a similar method was developed using a portable IR spectrometer, the InfraSpecTM VFA-IR spectrometer. As a result, the data collected gave a good linear fit for % purity of the samples and can be used as a method for monitoring the conversion of different types of oils to biodiesel and determining the purity of biodiesel produced from oil.« less

Production of needle-type liquid-metal ion sources and their application in a scanning ion muscope

NASA Astrophysics Data System (ADS)

Knapp, Helmut; Rübesame, Detlef; Niedrig, Heinz

1991-07-01

A tungsten wire is electrochemically etched in NaOH to produce tip radii of 4-10 μm for use in liquid-metal ion sources (LMIS). To ensure complete wetting of the needle with the liquid metal (Sn, Ga), the needle has to be annealed at 800-1000°C by electron bombardment in a vacuum. It is then immediately dipped into the liquid metal in the same vacuum chamber. An anode prepared in this way is part of a triode system, followed by an octupole stigmator, an electrostatic einzel lens and the scanning unit. Upon application of a high voltage the liquid metal will form a Taylor cone at the needle tip. In the resulting high electrical field ions are extracted through field evaporation. Typical beam current and spot size values during scanning ion muscope (SIM) operation are 2.5 μA and 10 μm respectively. An Everhart-Thornley detector and a quadrupole mass spectrometer are available to allow analysis of secondary particles emitted from the target.

Engineering helimagnetism in MnSi thin films

NASA Astrophysics Data System (ADS)

Zhang, S. L.; Chalasani, R.; Baker, A. A.; Steinke, N.-J.; Figueroa, A. I.; Kohn, A.; van der Laan, G.; Hesjedal, T.

2016-01-01

Magnetic skyrmion materials have the great advantage of a robust topological magnetic structure, which makes them stable against the superparamagnetic effect and therefore a candidate for the next-generation of spintronic memory devices. Bulk MnSi, with an ordering temperature of 29.5 K, is a typical skyrmion system with a propagation vector periodicity of ˜18 nm. One crucial prerequisite for any kind of application, however, is the observation and precise control of skyrmions in thin films at room-temperature. Strain in epitaxial MnSi thin films is known to raise the transition temperature to 43 K. Here we show, using magnetometry and x-ray spectroscopy, that the transition temperature can be raised further through proximity coupling to a ferromagnetic layer. Similarly, the external field required to stabilize the helimagnetic phase is lowered. Transmission electron microscopy with element-sensitive detection is used to explore the structural origin of ferromagnetism in these Mn-doped substrates. Our work suggests that an artificial pinning layer, not limited to the MnSi/Si system, may enable room temperature, zero-field skyrmion thin-film systems, thereby opening the door to device applications.

Influence of Joule heating on current-induced domain wall depinning

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

Moretti, Simone, E-mail: simone.moretti@usal.es; Raposo, Victor; Martinez, Eduardo

2016-06-07

The domain wall depinning from a notch in a Permalloy nanostrip on top of a SiO{sub 2}/Si substrate is studied theoretically under application of static magnetic fields and the injection of short current pulses. The influence of Joule heating on current-induced domain wall depinning is explored self-consistently by coupling the magnetization dynamics in the ferromagnetic strip to the heat transport throughout the system. Our results indicate that Joule heating plays a remarkable role in these processes, resulting in a reduction in the critical depinning field and/or in a temporary destruction of the ferromagnetic order for typically injected current pulses. Inmore » agreement with experimental observations, similar pinning-depinning phase diagrams can be deduced for both current polarities when the Joule heating is taken into account. These observations, which are incompatible with the sole contribution of spin transfer torques, provide a deeper understanding of the physics underlying these processes and establish the real scope of the spin transfer torque. They are also relevant for technological applications based on current-induced domain-wall motion along soft strips.« less

Repair of full-thickness tendon injury using connective tissue progenitors efficiently derived from human embryonic stem cells and fetal tissues.

PubMed

Cohen, Shahar; Leshansky, Lucy; Zussman, Eyal; Burman, Michael; Srouji, Samer; Livne, Erella; Abramov, Natalie; Itskovitz-Eldor, Joseph

2010-10-01

The use of stem cells for tissue engineering (TE) encourages scientists to design new platforms in the field of regenerative and reconstructive medicine. Human embryonic stem cells (hESC) have been proposed to be an important cell source for cell-based TE applications as well as an exciting tool for investigating the fundamentals of human development. Here, we describe the efficient derivation of connective tissue progenitors (CTPs) from hESC lines and fetal tissues. The CTPs were significantly expanded and induced to generate tendon tissues in vitro, with ultrastructural characteristics and biomechanical properties typical of mature tendons. We describe a simple method for engineering tendon grafts that can successfully repair injured Achilles tendons and restore the ankle joint extension movement in mice. We also show the CTP's ability to differentiate into bone, cartilage, and fat both in vitro and in vivo. This study offers evidence for the possibility of using stem cell-derived engineered grafts to replace missing tissues, and sets a basic platform for future cell-based TE applications in the fields of orthopedics and reconstructive surgery.

Using IR spectroscopy to determine biodiesel conversion

DOE PAGES

Tirla, Cornelia; Dooling, Thomas; Smith, Rachel B.; ...

2013-01-01

This project’s aim was to develop a way to use Infrared (IR) Spectroscopy to determine the extent of the conversion of oil to biodiesel produced during a typical transesterification process. The most reliable method of biodiesel analysis is gas chromatography with flame ionization detector (GC-FID) analysis. This analysis is not ideal for the educational or field applications since it is time intensive and requires expensive, specialized equipment. The use of the FT-IR is faster and more affordable. A calibration curve was created by comparing data on the purity of biodiesel samples obtained from the GC-FID analysis to the ratio ofmore » the absorbances at 1197 cm -1 to 1166 cm -1 from the FT-IR spectrum. For field application, a similar method was developed using a portable IR spectrometer, the InfraSpecTM VFA-IR spectrometer. As a result, the data collected gave a good linear fit for % purity of the samples and can be used as a method for monitoring the conversion of different types of oils to biodiesel and determining the purity of biodiesel produced from oil.« less

Negative to positive crossover of the magnetoresistance in layered WS{sub 2}

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

Zhang, Yangwei; Ning, Honglie; Li, Yanan

2016-04-11

The discovery of graphene ignited intensive investigation of two-dimensional materials. A typical two-dimensional material, transition metal dichalcogenide (TMDC), attracts much attention because of its excellent performance in field effect transistor measurements and applications. Particularly, when TMDC reaches the dimension of a few layers, a wide range of electronic and optical properties can be detected that are in striking contrast to bulk samples. In this letter, we synthesized WS{sub 2} single-crystal nanoflakes using physical vapor deposition and carried out a series of measurements of the contact resistance and magnetoresistance. Focused ion beam (FIB) technology was applied to deposit Pt electrodes onmore » the WS{sub 2} flakes, and the FIB-deposited contacts exhibited linear electrical characteristics. Resistance versus temperature measurements showed similar Mott variable range hopping behavior in different magnetic fields. Additionally, a temperature-modulated negative-to-positive magnetoresistance transition was observed. Our work reveals the magnetotransport characteristics of WS{sub 2} flakes, which may stimulate further studies of the properties of TMDC and its corresponding electronic and optoelectronic applications.« less

Research on application of LADAR in ground vehicle recognition

NASA Astrophysics Data System (ADS)

Lan, Jinhui; Shen, Zhuoxun

2009-11-01

For the requirement of many practical applications in the field of military, the research of 3D target recognition is active. The representation that captures the salient attributes of a 3D target independent of the viewing angle will be especially useful to the automatic 3D target recognition system. This paper presents a new approach of image generation based on Laser Detection and Ranging (LADAR) data. Range image of target is obtained by transformation of point cloud. In order to extract features of different ground vehicle targets and to recognize targets, zernike moment properties of typical ground vehicle targets are researched in this paper. A technique of support vector machine is applied to the classification and recognition of target. The new method of image generation and feature representation has been applied to the outdoor experiments. Through outdoor experiments, it can be proven that the method of image generation is stability, the moments are effective to be used as features for recognition, and the LADAR can be applied to the field of 3D target recognition.

Performance evaluation of a distance learning program.

PubMed

Dailey, D J; Eno, K R; Brinkley, J F

1994-01-01

This paper presents a performance metric which uses a single number to characterize the response time for a non-deterministic client-server application operating over the Internet. When applied to a Macintosh-based distance learning application called the Digital Anatomist Browser, the metric allowed us to observe that "A typical student doing a typical mix of Browser commands on a typical data set will experience the same delay if they use a slow Macintosh on a local network or a fast Macintosh on the other side of the country accessing the data over the Internet." The methodology presented is applicable to other client-server applications that are rapidly appearing on the Internet.

Development and validation of a novel large field of view phantom and a software module for the quality assurance of geometric distortion in magnetic resonance imaging.

PubMed

Torfeh, Tarraf; Hammoud, Rabih; McGarry, Maeve; Al-Hammadi, Noora; Perkins, Gregory

2015-09-01

To develop and validate a large field of view phantom and quality assurance software tool for the assessment and characterization of geometric distortion in MRI scanners commissioned for radiation therapy planning. A purpose built phantom was developed consisting of 357 rods (6mm in diameter) of polymethyl-methacrylat separated by 20mm intervals, providing a three dimensional array of control points at known spatial locations covering a large field of view up to a diameter of 420mm. An in-house software module was developed to allow automatic geometric distortion assessment. This software module was validated against a virtual dataset of the phantom that reproduced the exact geometry of the physical phantom, but with known translational and rotational displacements and warping. For validation experiments, clinical MRI sequences were acquired with and without the application of a commercial 3D distortion correction algorithm (Gradwarp™). The software module was used to characterize and assess system-related geometric distortion in the sequences relative to a benchmark CT dataset, and the efficacy of the vendor geometric distortion correction algorithms (GDC) was also assessed. Results issued from the validation of the software against virtual images demonstrate the algorithm's ability to accurately calculate geometric distortion with sub-pixel precision by the extraction of rods and quantization of displacements. Geometric distortion was assessed for the typical sequences used in radiotherapy applications and over a clinically relevant 420mm field of view (FOV). As expected and towards the edges of the field of view (FOV), distortion increased with increasing FOV. For all assessed sequences, the vendor GDC was able to reduce the mean distortion to below 1mm over a field of view of 5, 10, 15 and 20cm radius respectively. Results issued from the application of the developed phantoms and algorithms demonstrate a high level of precision. The results indicate that this platform represents an important, robust and objective tool to perform routine quality assurance of MR-guided therapeutic applications, where spatial accuracy is paramount. Copyright © 2015 Elsevier Inc. All rights reserved.

Superconducting transition detectors for low-energy gamma-ray astrophysics

NASA Astrophysics Data System (ADS)

Kurfess, J. D.; Johnson, W. N.; Fritz, G. G.; Strickman, M. S.; Kinzer, R. L.; Jung, G.; Drukier, A. K.; Chmielowski, M.

1990-08-01

A program to investigate superconducting devices such as STDs for use in high-resolution Compton telescopes and coded-aperture detectors is presented. For higher energy applications, techniques are investigated with potential for scaling to large detectors, while also providing excellent energy and positional resolution. STDs are discussed, utilizing a uniform array of spherical granules tens of microns in diameter. The typical temperature-magnetic field phase for a low-temperature superconductor, the signal produced by the superconducting-normal transition in the 32-m diameter Sn granule, and the temperature history of an STD granule following heating by an ionizing particle are illustrated.

Parallelization and visual analysis of multidimensional fields: Application to ozone production, destruction, and transport in three dimensions

NASA Technical Reports Server (NTRS)

Schwan, Karsten

1994-01-01

Atmospheric modeling is a grand challenge problem for several reasons, including its inordinate computational requirements and its generation of large amounts of data concurrent with its use of very large data sets derived from measurement instruments like satellites. In addition, atmospheric models are typically run several times, on new data sets or to reprocess existing data sets, to investigate or reinvestigate specific chemical or physical processes occurring in the earth's atmosphere, to understand model fidelity with respect to observational data, or simply to experiment with specific model parameters or components.

Probabilistic modeling of the indoor climates of residential buildings using EnergyPlus

DOE PAGES

Buechler, Elizabeth D.; Pallin, Simon B.; Boudreaux, Philip R.; ...

2017-04-25

The indoor air temperature and relative humidity in residential buildings significantly affect material moisture durability, HVAC system performance, and occupant comfort. Therefore, indoor climate data is generally required to define boundary conditions in numerical models that evaluate envelope durability and equipment performance. However, indoor climate data obtained from field studies is influenced by weather, occupant behavior and internal loads, and is generally unrepresentative of the residential building stock. Likewise, whole-building simulation models typically neglect stochastic variables and yield deterministic results that are applicable to only a single home in a specific climate. The

The effects of sampling location and turbulence on discharge estimates in short converging turbine intakes

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

Romero-Gomez, P.; Harding, S. F.; Richmond, M. C.

2017-01-01

Standards provide recommendations for best practices when installing current meters to measure fluid flow in closed conduits. A central guideline requires the velocity distribution to be regular and the flow steady. Because of the nature of the short converging intakes typical of low-head hydroturbines, these assumptions may be invalid if current meters are intended to be used to estimate discharge. Usual concerns are (1) the effects of the number of devices, (2) the sampling location and (3) the high turbulence caused by blockage from submersible traveling screens usually deployed for safe downstream fish passage. These three effects were examined inmore » the present study by using 3D simulated flow fields in both steady-state and transient modes. In the process of describing an application at an existing hydroturbine intake at Ice Harbor Dam, the present work outlined the methods involved, which combined computational fluid dynamics, laboratory measurements in physical models of the hydroturbine, and current meter performance evaluations in experimental settings. The main conclusions in this specific application were that a steady-state flow field sufficed to determine the adequate number of meters and their location, and that both the transverse velocity and turbulence intensity had a small impact on estimate errors. However, while it may not be possible to extrapolate these findings to other field conditions and measuring devices, the study laid out a path to conduct similar assessments in other applications.« less

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

PubMed

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

2018-06-27

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

Micelles as Delivery Vehicles for Oligofluorene for Bioimaging

PubMed Central

Su, Fengyu; Alam, Ruhaniyah; Mei, Qian; Tian, Yanqing; Meldrum, Deirdre R.

2011-01-01

With the successful development of organic/polymeric light emitting diodes, many organic and polymeric fluorophores with high quantum efficiencies and optical stability were synthesized. However, most of these materials which have excellent optical properties are insoluble in water, limiting their applications in biological fields. Herein, we used micelles formed from an amino-group-containing poly(ε-caprolactone)-block-poly(ethylene glycol) (PCL-b-PEG-NH2) to incorporate a hydrophobic blue emitter oligofluorene (OF) to enable its application in biological conditions. Although OF is completely insoluble in water, it was successfully transferred into aqueous solutions with a good retention of its photophysical properties. OF exhibited a high quantum efficiency of 0.84 in a typical organic solvent of tetrahydrofuran (THF). In addition, OF also showed a good quantum efficiency of 0.46 after being encapsulated into micelles. Two cells lines, human glioblastoma (U87MG) and esophagus premalignant (CP-A), were used to study the cellular internalization of the OF incorporated micelles. Results showed that the hydrophobic OF was located in the cytoplasm, which was confirmed by co-staining the cells with nucleic acid specific SYTO 9, lysosome specific LysoTracker Red®, and mitochondria specific MitoTracker Red. MTT assay indicated non-toxicity of the OF-incorporated micelles. This study will broaden the application of hydrophobic functional organic compounds, oligomers, and polymers with good optical properties to enable their applications in biological research fields. PMID:21915324

Micelles as delivery vehicles for oligofluorene for bioimaging.

PubMed

Su, Fengyu; Alam, Ruhaniyah; Mei, Qian; Tian, Yanqing; Meldrum, Deirdre R

2011-01-01

With the successful development of organic/polymeric light emitting diodes, many organic and polymeric fluorophores with high quantum efficiencies and optical stability were synthesized. However, most of these materials which have excellent optical properties are insoluble in water, limiting their applications in biological fields. Herein, we used micelles formed from an amino-group-containing poly(ε-caprolactone)-block-poly(ethylene glycol) (PCL-b-PEG-NH(2)) to incorporate a hydrophobic blue emitter oligofluorene (OF) to enable its application in biological conditions. Although OF is completely insoluble in water, it was successfully transferred into aqueous solutions with a good retention of its photophysical properties. OF exhibited a high quantum efficiency of 0.84 in a typical organic solvent of tetrahydrofuran (THF). In addition, OF also showed a good quantum efficiency of 0.46 after being encapsulated into micelles. Two cells lines, human glioblastoma (U87MG) and esophagus premalignant (CP-A), were used to study the cellular internalization of the OF incorporated micelles. Results showed that the hydrophobic OF was located in the cytoplasm, which was confirmed by co-staining the cells with nucleic acid specific SYTO 9, lysosome specific LysoTracker Red®, and mitochondria specific MitoTracker Red. MTT assay indicated non-toxicity of the OF-incorporated micelles. This study will broaden the application of hydrophobic functional organic compounds, oligomers, and polymers with good optical properties to enable their applications in biological research fields.

Large area full-field optical coherence tomography using white light source

NASA Astrophysics Data System (ADS)

Chang, Shoude; Mao, Youxin; Sherif, Sherif; Flueraru, Costel

2007-06-01

Optical coherence tomography (OCT) is an emerging technology for high-resolution cross-sectional imaging of 3D structures. Not only could OCT extract the internal features of an object, but it could acquire the 3D profile of an object as well. Hence it has huge potentials for industrial applications. Owing to non-scanning along the X-Y axis, full-field OCT could be the simplest and most economic imaging system, especially for applications where the speed is critical. For an OCT system, the performance and cost basically depends on the light source being used. The broader the source bandwidth, the finer of the depth resolution that could be reached; the more power of the source, the better signal-to-noise ratio and the deeper of penetration the system achieves. A typical SLD (Superluminescent Diode) light source has a bandwidth of 15 nm and 10 mW optical power at a price around 6,000. However, a Halogen bulb having 50W power and 200nm bandwidth only costs less than 10. The design and implementation of a large-area, full-field OCT system using Halogen white-light source is described in the paper. The experimental results obtained from 3D shaping and multiple-layer tomographies are also presented.

Towards integrated pest management in red clover seed production.

PubMed

Lundin, Ola; Rundlöf, Maj; Smith, Henrik G; Bommarco, Riccardo

2012-10-01

The development of integrated pest management is hampered by lack of information on how insect pest abundances relate to yield losses, and how pests are affected by control measures. In this study, we develop integrated pest management tactics for Apion spp. weevils (Coleoptera: Brentidae) in seed production of red clover, Trifolium pratense L. We tested a method to forecast pest damage, quantified the relationship between pest abundance and yield, and evaluated chemical and biological pest control in 29 Swedish red clover fields in 2008 and 2011. Pest inflorescence abundance, which had a highly negative effect on yield, could be predicted with pan trap catches of adult pests. In 2008, chemical control with typically one application of pyrethroids was ineffective both in decreasing pest abundances and in increasing yields. In 2011, when chemical control included applications of the neonicotinoid thiacloprid, pest abundances decreased and yields increased considerably in treated field zones. A post hoc analysis indicated that using pyrethroids in addition to thiacloprid was largely redundant. Infestation rates by parasitoids was higher and reached average levels of around 40% in insecticide treated field zones in 2011, which is a level of interest for biological pest control. Based on the data presented, an economic threshold for chemical control is developed, and guidelines are provided on minimum effective chemical pest control.

Nanogap near-field thermophotovoltaics.

PubMed

Fiorino, Anthony; Zhu, Linxiao; Thompson, Dakotah; Mittapally, Rohith; Reddy, Pramod; Meyhofer, Edgar

2018-06-18

Conversion of heat to electricity via solid-state devices is of great interest and has led to intense research of thermoelectric materials 1,2 . Alternative approaches for solid-state heat-to-electricity conversion include thermophotovoltaic (TPV) systems where photons from a hot emitter traverse a vacuum gap and are absorbed by a photovoltaic (PV) cell to generate electrical power. In principle, such systems may also achieve higher efficiencies and offer more versatility in use. However, the typical temperature of the hot emitter remains too low (<1,000 K) to achieve a sufficient photon flux to the PV cell, limiting practical applications. Theoretical proposals 3-12 suggest that near-field (NF) effects 13-18 that arise in nanoscale gaps may be leveraged to increase the photon flux to the PV cell and significantly enhance the power output. Here, we describe functional NFTPV devices consisting of a microfabricated system and a custom-built nanopositioner and demonstrate an ~40-fold enhancement in the power output at nominally 60 nm gaps relative to the far field. We systematically characterize this enhancement over a range of gap sizes and emitter temperatures, and for PV cells with two different bandgap energies. We anticipate that this technology, once optimized, will be viable for waste heat recovery applications.

Drift-Free Indoor Navigation Using Simultaneous Localization and Mapping of the Ambient Heterogeneous Magnetic Field

NASA Astrophysics Data System (ADS)

Chow, J. C. K.

2017-09-01

In the absence of external reference position information (e.g. surveyed targets or Global Navigation Satellite Systems) Simultaneous Localization and Mapping (SLAM) has proven to be an effective method for indoor navigation. The positioning drift can be reduced with regular loop-closures and global relaxation as the backend, thus achieving a good balance between exploration and exploitation. Although vision-based systems like laser scanners are typically deployed for SLAM, these sensors are heavy, energy inefficient, and expensive, making them unattractive for wearables or smartphone applications. However, the concept of SLAM can be extended to non-optical systems such as magnetometers. Instead of matching features such as walls and furniture using some variation of the Iterative Closest Point algorithm, the local magnetic field can be matched to provide loop-closure and global trajectory updates in a Gaussian Process (GP) SLAM framework. With a MEMS-based inertial measurement unit providing a continuous trajectory, and the matching of locally distinct magnetic field maps, experimental results in this paper show that a drift-free navigation solution in an indoor environment with millimetre-level accuracy can be achieved. The GP-SLAM approach presented can be formulated as a maximum a posteriori estimation problem and it can naturally perform loop-detection, feature-to-feature distance minimization, global trajectory optimization, and magnetic field map estimation simultaneously. Spatially continuous features (i.e. smooth magnetic field signatures) are used instead of discrete feature correspondences (e.g. point-to-point) as in conventional vision-based SLAM. These position updates from the ambient magnetic field also provide enough information for calibrating the accelerometer bias and gyroscope bias in-use. The only restriction for this method is the need for magnetic disturbances (which is typically not an issue for indoor environments); however, no assumptions are required for the general motion of the sensor (e.g. static periods).

Wide gap active brazing of ceramic-to-metal-joints for high temperature applications

NASA Astrophysics Data System (ADS)

Bobzin, K.; Zhao, L.; Kopp, N.; Samadian Anavar, S.

2014-03-01

Applications like solid oxide fuel cells and sensors increasingly demand the possibility to braze ceramics to metals with a good resistance to high temperatures and oxidative atmospheres. Commonly used silver based active filler metals cannot fulfill these requirements, if application temperatures higher than 600°C occur. Au and Pd based active fillers are too expensive for many fields of use. As one possible solution nickel based active fillers were developed. Due to the high brazing temperatures and the low ductility of nickel based filler metals, the modification of standard nickel based filler metals were necessary to meet the requirements of above mentioned applications. To reduce thermally induced stresses wide brazing gaps and the addition of Al2O3 and WC particles to the filler metal were applied. In this study, the microstructure of the brazed joints and the thermo-chemical reactions between filler metal, active elements and WC particles were analyzed to understand the mechanism of the so called wide gap active brazing process. With regard to the behavior in typical application oxidation and thermal cycle tests were conducted as well as tensile tests.

Ultrasonic Microtransport

NASA Astrophysics Data System (ADS)

Moroney, Richard Morgan, III

We have observed numerous kinetic effects using ultrasonic flexural plate waves (FPWs) in 4mu -thick composite plates of low-stress silicon nitride, piezoelectric zinc oxide and aluminum. The wavelength is typically 100 mum, and the area 3 x 8 mm^2. A successful new surface micromachining fabrication process is presented here for the first time. FPWs have been used to move liquids and gasses with motion typically indicated by polysilicon blocks in air and polystyrene spheres in water; the velocity in air is 4.5 mm/s (with a zero-to-peak input of 3 V), and in water it is 100 mum/s (with an input of 7.8 V). Other observations include pumping of a liquid dye, and mixing near the FPW surface. All quantitative observations demonstrate that the kinetic effects of FPWs are proportional to the square of the wave amplitude. The amplitude for a typical device is 250 A at 9 V input; the power in a typical FPW is about 2 mW. The amplitude can be accurately measured using a laser diffraction technique. Experimental error is about +/-10%, and many of the results agree well with a simple theory to predict the FPW amplitude; extensions of the theory model the fluid loading of FPW devices, but experiment and theory disagree by about 15%. Pumping by flexural plate waves is an example of the phenomenon known as acoustic streaming. A common solution approach is the method of successive approximations, where the nonlinear equations are first linearized and solved. This "first-order" solution is then used to determine the inhomogeneous source terms in the linearized, "second -order" equations of motion. Theoretical predictions of streaming theory are in excellent agreement with experiment in the case where the FPW device contacts a half-space of fluid; predictions for flow in small channels encourage the development of integrated micropumps. Applications for microflow include thermal redistribution in integrated circuits and liquid movement in analytical instruments--particularly where a small dead volume is required. Capabilities of this technology and further applications are discussed. Microflow systems that integrate transport of fluids and solids with sensing, mixing and other useful tasks may become a new market-leading application for the sensor and actuator field.

Agricultural, domestic and handicraft folk uses of plants in the Tyrrhenian sector of Basilicata (Italy)

PubMed Central

Salerno, Giovanni; Guarrera, Paolo Maria; Caneva, Giulia

2005-01-01

Background Research was carried out into agricultural and domestic-handicraft uses in folk traditions in the Tyrrhenian sector of the Basilicata region (southern Italy), as it is typically representative of ethnobotanical applications in the Mediterranean area. From the point of view of furnishing a botanical support for the study of local "material culture" data was collected through field interviews of 49 informants, most of whom were farmers. Results The taxa cited are 60, belonging to 32 botanical families, of which 18 are employed for agricultural uses and 51 for domestic-handicraft folk uses. Data show a diffuse use of plants for many purposes, both in agricultural (present uses 14%; past uses 1%) and for domestic-handicraft use (present uses 40%; past uses 45%); most of the latter are now in decline. Conclusion 60 data look uncommon or typical of the places studied. Some domestic-handicraft folk uses are typical of southern Italy (e.g. the use of Ampelodesmos mauritanicus for making ties, ropes, torches, baskets or that of Acer neapolitanum for several uses). Other uses (e.g. that of Inula viscosa and Calamintha nepeta for peculiar brooms, and of Origanum heracleoticum for dyeing wool red) are previously unpublished. PMID:16270919

Amyloid β Enhances Typical Rodent Behavior While It Impairs Contextual Memory Consolidation.

PubMed

Salgado-Puga, Karla; Prado-Alcalá, Roberto A; Peña-Ortega, Fernando

2015-01-01

Alzheimer's disease (AD) is associated with an early hippocampal dysfunction, which is likely induced by an increase in soluble amyloid beta peptide (Aβ). This hippocampal failure contributes to the initial memory deficits observed both in patients and in AD animal models and possibly to the deterioration in activities of daily living (ADL). One typical rodent behavior that has been proposed as a hippocampus-dependent assessment model of ADL in mice and rats is burrowing. Despite the fact that AD transgenic mice show some evidence of reduced burrowing, it has not been yet determined whether or not Aβ can affect this typical rodent behavior and whether this alteration correlates with the well-known Aβ-induced memory impairment. Thus, the purpose of this study was to test whether or not Aβ affects burrowing while inducing hippocampus-dependent memory impairment. Surprisingly, our results show that intrahippocampal application of Aβ increases burrowing while inducing memory impairment. We consider that this Aβ-induced increase in burrowing might be associated with a mild anxiety state, which was revealed by increased freezing behavior in the open field, and conclude that Aβ-induced hippocampal dysfunction is reflected in the impairment of ADL and memory, through mechanisms yet to be determined.

Electro-optical effects in porous PET films filled with liquid crystal: new possibilities for fiber optics and THZ applications.

PubMed

Chopik, A; Pasechnik, S; Semerenko, D; Shmeliova, D; Dubtsov, A; Srivastava, A K; Chigrinov, V

2014-03-15

The results of investigation of electro-optical properties of porous polyethylene terephthalate films filled with a nematic liquid crystal (5 CB) are presented. It is established that the optical response of the samples on the applied voltage drastically depends on the frequency range. At low frequencies of applied electrical field (ffc) electric field induces an overall change in the light intensity, which is typical for an electro-optical response of a liquid crystal (LC) layer in a conventional "sandwich"-like cell. The dependences of critical frequency fc, threshold voltages, and characteristic times on a pore diameter d were established. The peculiarities of electro-optical effects can be explained in the framework of the approach which connects the variations of light intensity with the corresponding changes of the effective refractive index n(eff) of a composite LC media. The unusual behavior of the electro-optical response at low frequencies is assigned to the orienting action of the specific shear flow typical for electrokinetic phenomena in polar liquids.

High-harmonic generation by field enhanced femtosecond pulses in metal-sapphire nanostructure

PubMed Central

Han, Seunghwoi; Kim, Hyunwoong; Kim, Yong Woo; Kim, Young-Jin; Kim, Seungchul; Park, In-Yong; Kim, Seung-Woo

2016-01-01

Plasmonic high-harmonic generation (HHG) drew attention as a means of producing coherent extreme ultraviolet (EUV) radiation by taking advantage of field enhancement occurring in metallic nanostructures. Here a metal-sapphire nanostructure is devised to provide a solid tip as the HHG emitter, replacing commonly used gaseous atoms. The fabricated solid tip is made of monocrystalline sapphire surrounded by a gold thin-film layer, and intended to produce EUV harmonics by the inter- and intra-band oscillations of electrons driven by the incident laser. The metal-sapphire nanostructure enhances the incident laser field by means of surface plasmon polaritons, triggering HHG directly from moderate femtosecond pulses of ∼0.1 TW cm−2 intensities. The measured EUV spectra exhibit odd-order harmonics up to ∼60 nm wavelengths without the plasma atomic lines typically seen when using gaseous atoms as the HHG emitter. This experimental outcome confirms that the plasmonic HHG approach is a promising way to realize coherent EUV sources for nano-scale near-field applications in spectroscopy, microscopy, lithography and atto-second physics. PMID:27721374

A focusing reflectarray and its application in microwave virus sanitizer

NASA Astrophysics Data System (ADS)

Hung, Wan-Ting; Tung, Jen-Jung; Chen, Shih-Yuan

2014-10-01

In this paper, a focusing reflectarray based on the conductor-backed strip dipole unit cell is proposed and designed for use in the microwave virus sanitizer. Unlike traditional far-field antennas that form a planar phase front in a specified far-field direction, the focusing reflectarray is designed to coherently add the fields radiated from the feeding antenna at a predetermined focal point, typically within its radiating near-field region and to ensure adequate power density to inactivate the H3N2 virus sample. Furthermore, the focusing reflectarray has a simple and planar structure compared with conventional focusing antennas. Since the microwave resonant absorption frequency of the H3N2 virus is at about 8 GHz, an 8 × 8 focusing reflectarray is designed for operation at 8 GHz. A prototype antenna is then fabricated and used for H3N2 virus sanitization. It is demonstrated experimentally that the death rate of the H3N2 virus sample is up to 93%, verifying the feasibility of the microwave virus sanitizer as well as the proposed focusing reflectarray.

Collision Models for Particle Orbit Code on SSX

NASA Astrophysics Data System (ADS)

Fisher, M. W.; Dandurand, D.; Gray, T.; Brown, M. R.; Lukin, V. S.

2011-10-01

Coulomb collision models are being developed and incorporated into the Hamiltonian particle pushing code (PPC) for applications to the Swarthmore Spheromak eXperiment (SSX). A Monte Carlo model based on that of Takizuka and Abe [JCP 25, 205 (1977)] performs binary collisions between test particles and thermal plasma field particles randomly drawn from a stationary Maxwellian distribution. A field-based electrostatic fluctuation model scatters particles from a spatially uniform random distribution of positive and negative spherical potentials generated throughout the plasma volume. The number, radii, and amplitude of these potentials are chosen to mimic the correct particle diffusion statistics without the use of random particle draws or collision frequencies. An electromagnetic fluctuating field model will be presented, if available. These numerical collision models will be benchmarked against known analytical solutions, including beam diffusion rates and Spitzer resistivity, as well as each other. The resulting collisional particle orbit models will be used to simulate particle collection with electrostatic probes in the SSX wind tunnel, as well as particle confinement in typical SSX fields. This work has been supported by US DOE, NSF and ONR.

Graphene and graphene-like layered transition metal dichalcogenides in energy conversion and storage.

PubMed

Wang, Hua; Feng, Hongbin; Li, Jinghong

2014-06-12

Being confronted with the energy crisis and environmental problems, the exploration of clean and renewable energy materials as well as their devices are urgently demanded. Two-dimensional (2D) atomically-thick materials, graphene and grpahene-like layered transition metal dichalcogenides (TMDs), have showed vast potential as novel energy materials due to their unique physicochemical properties. In this Review, we outline the typical application of graphene and grpahene-like TMDs in energy conversion and storage fields, and hope to promote the development of 2D TMDs in this field through the analysis and comparisons with the relatively natural graphene. First, a brief introduction of electronic structures and basic properties of graphene and TMDs are presented. Then, we summarize the exciting progress of these materials made in both energy conversion and storage field including solar cells, electrocatalysis, supercapacitors and lithium ions batteries. Finally, the prospects and further developments in these exciting fields of graphene and graphene-like TMDs materials are also suggested. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Elimination of the Reaction Rate "Scale Effect": Application of the Lagrangian Reactive Particle-Tracking Method to Simulate Mixing-Limited, Field-Scale Biodegradation at the Schoolcraft (MI, USA) Site

NASA Astrophysics Data System (ADS)

Ding, Dong; Benson, David A.; Fernández-Garcia, Daniel; Henri, Christopher V.; Hyndman, David W.; Phanikumar, Mantha S.; Bolster, Diogo

2017-12-01

Measured (or empirically fitted) reaction rates at groundwater remediation sites are typically much lower than those found in the same material at the batch or laboratory scale. The reduced rates are commonly attributed to poorer mixing at the larger scales. A variety of methods have been proposed to account for this scaling effect in reactive transport. In this study, we use the Lagrangian particle-tracking and reaction (PTR) method to simulate a field bioremediation experiment at the Schoolcraft, MI site. A denitrifying bacterium, Pseudomonas Stutzeri strain KC (KC), was injected to the aquifer, along with sufficient substrate, to degrade the contaminant, carbon tetrachloride (CT), under anaerobic conditions. The PTR method simulates chemical reactions through probabilistic rules of particle collisions, interactions, and transformations to address the scale effect (lower apparent reaction rates for each level of upscaling, from batch to column to field scale). In contrast to a prior Eulerian reaction model, the PTR method is able to match the field-scale experiment using the rate coefficients obtained from batch experiments.

Scientific impact: opportunity and necessity.

PubMed

Cohen, Marlene Z; Alexander, Gregory L; Wyman, Jean F; Fahrenwald, Nancy L; Porock, Davina; Wurzbach, Mary E; Rawl, Susan M; Conn, Vicki S

2010-08-01

Recent National Institutes of Health changes have focused attention on the potential scientific impact of research projects. Research with the excellent potential to change subsequent science or health care practice may have high scientific impact. Only rigorous studies that address highly significant problems can generate change. Studies with high impact may stimulate new research approaches by changing understanding of a phenomenon, informing theory development, or creating new research methods that allow a field of science to move forward. Research with high impact can transition health care to more effective and efficient approaches. Studies with high impact may propel new policy developments. Research with high scientific impact typically has both immediate and sustained influence on the field of study. The article includes ideas to articulate potential scientific impact in grant applications as well as possible dissemination strategies to enlarge the impact of completed projects.

Electrochemical detection for microscale analytical systems: a review.

PubMed

Wang, Joseph

2002-02-11

As the field of chip-based microscale systems continues its rapid growth, there are urgent needs for developing compatible detection modes. Electrochemistry detection offers considerable promise for such microfluidic systems, with features that include remarkable sensitivity, inherent miniaturization and portability, independence of optical path length or sample turbidity, low cost, low-power requirements and high compatibility with advanced micromachining and microfabrication technologies. This paper highlights recent advances, directions and key strategies in controlled-potential electrochemical detectors for miniaturized analytical systems. Subjects covered include the design and integration of the electrochemical detection system, its requirements and operational principles, common electrode materials, derivatization reactions, electrical-field decouplers, typical applications and future prospects. It is expected that electrochemical detection will become a powerful tool for microscale analytical systems and will facilitate the creation of truly portable (and possibly disposable) devices.

Attosecond electron bunches from a nanofiber driven by Laguerre-Gaussian laser pulses.

PubMed

Hu, Li-Xiang; Yu, Tong-Pu; Sheng, Zheng-Ming; Vieira, Jorge; Zou, De-Bin; Yin, Yan; McKenna, Paul; Shao, Fu-Qiu

2018-05-08

Generation of attosecond bunches of energetic electrons offers significant potential from ultrafast physics to novel radiation sources. However, it is still a great challenge to stably produce such electron beams with lasers, since the typical subfemtosecond electron bunches from laser-plasma interactions either carry low beam charge, or propagate for only several tens of femtoseconds. Here we propose an all-optical scheme for generating dense attosecond electron bunches via the interaction of an intense Laguerre-Gaussian (LG) laser pulse with a nanofiber. The dense bunch train results from the unique field structure of a circularly polarized LG laser pulse, enabling each bunch to be phase-locked and accelerated forward with low divergence, high beam charge and large beam-angular-momentum. This paves the way for wide applications in various fields, e.g., ultrabrilliant attosecond x/γ-ray emission.

Dissipated power and induced velocity fields data of a micro single dielectric barrier discharge plasma actuator for active flow control☆

PubMed Central

Pescini, E.; Martínez, D.S.; De Giorgi, M.G.; Francioso, L.; Ficarella, A.

2015-01-01

In recent years, single dielectric barrier discharge (SDBD) plasma actuators have gained great interest among all the active flow control devices typically employed in aerospace and turbomachinery applications [1,2]. Compared with the macro SDBDs, the micro single dielectric barrier discharge (MSDBD) actuators showed a higher efficiency in conversion of input electrical power to delivered mechanical power [3,4]. This article provides data regarding the performances of a MSDBD plasma actuator [5,6]. The power dissipation values [5] and the experimental and numerical induced velocity fields [6] are provided. The present data support and enrich the research article entitled “Optimization of micro single dielectric barrier discharge plasma actuator models based on experimental velocity and body force fields” by Pescini et al. [6]. PMID:26425667

Error field penetration and locking to the backward propagating wave

DOE PAGES

Finn, John M.; Cole, Andrew J.; Brennan, Dylan P.

2015-12-30

In this letter we investigate error field penetration, or locking, behavior in plasmas having stable tearing modes with finite real frequencies w r in the plasma frame. In particular, we address the fact that locking can drive a significant equilibrium flow. We show that this occurs at a velocity slightly above v = w r/k, corresponding to the interaction with a backward propagating tearing mode in the plasma frame. Results are discussed for a few typical tearing mode regimes, including a new derivation showing that the existence of real frequencies occurs for viscoresistive tearing modes, in an analysis including themore » effects of pressure gradient, curvature and parallel dynamics. The general result of locking to a finite velocity flow is applicable to a wide range of tearing mode regimes, indeed any regime where real frequencies occur.« less

Laccase: Microbial Sources, Production, Purification, and Potential Biotechnological Applications

PubMed Central

Shraddha; Shekher, Ravi; Sehgal, Simran; Kamthania, Mohit; Kumar, Ajay

2011-01-01

Laccase belongs to the blue multicopper oxidases and participates in cross-linking of monomers, degradation of polymers, and ring cleavage of aromatic compounds. It is widely distributed in higher plants and fungi. It is present in Ascomycetes, Deuteromycetes and Basidiomycetes and abundant in lignin-degrading white-rot fungi. It is also used in the synthesis of organic substance, where typical substrates are amines and phenols, the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. In the recent years, these enzymes have gained application in the field of textile, pulp and paper, and food industry. Recently, it is also used in the design of biosensors, biofuel cells, as a medical diagnostics tool and bioremediation agent to clean up herbicides, pesticides and certain explosives in soil. Laccases have received attention of researchers in the last few decades due to their ability to oxidize both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants. It has been identified as the principal enzyme associated with cuticular hardening in insects. Two main forms have been found: laccase-1 and laccase-2. This paper reviews the occurrence, mode of action, general properties, production, applications, and immobilization of laccases within different industrial fields. PMID:21755038

Tunneling magnetoresistance sensor with pT level 1/f magnetic noise

NASA Astrophysics Data System (ADS)

Deak, James G.; Zhou, Zhimin; Shen, Weifeng

2017-05-01

Magnetoresistive devices are important components in a large number of commercial electronic products in a wide range of applications including industrial position sensors, automotive sensors, hard disk read heads, cell phone compasses, and solid state memories. These devices are commonly based on anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR), but over the past few years tunneling magnetoresistance (TMR) has been emerging in more applications. Here we focus on recent work that has enabled the development of TMR magnetic field sensors with 1/f noise of less than 100 pT/rtHz at 1 Hz. Of the commercially available sensors, the lowest noise devices have typically been AMR, but they generally have the largest die size. Based on this observation and modeling of experimental data size and geometry dependence, we find that there is an optimal design rule that produces minimum 1/f noise. This design rule requires maximizing the areal coverage of an on-chip flux concentrator, providing it with a minimum possible total gap width, and tightly packing the gaps with MTJ elements, which increases the effective volume and decreases the saturation field of the MTJ freelayers. When properly optimized using this rule, these sensors have noise below 60 pT/rtHz, and could possibly replace fluxgate magnetometers in some applications.

Design and market considerations for axial flux superconducting electric machine design

NASA Astrophysics Data System (ADS)

Ainslie, M. D.; George, A.; Shaw, R.; Dawson, L.; Winfield, A.; Steketee, M.; Stockley, S.

2014-05-01

In this paper, the authors investigate a number of design and market considerations for an axial flux superconducting electric machine design that uses high temperature superconductors. The axial flux machine design is assumed to utilise high temperature superconductors in both wire (stator winding) and bulk (rotor field) forms, to operate over a temperature range of 65-77 K, and to have a power output in the range from 10s of kW up to 1 MW (typical for axial flux machines), with approximately 2-3 T as the peak trapped field in the bulk superconductors. The authors firstly investigate the applicability of this type of machine as a generator in small- and medium-sized wind turbines, including the current and forecasted market and pricing for conventional turbines. Next, a study is also carried out on the machine's applicability as an in-wheel hub motor for electric vehicles. Some recommendations for future applications are made based on the outcome of these two studies. Finally, the cost of YBCO-based superconducting (2G HTS) wire is analysed with respect to competing wire technologies and compared with current conventional material costs and current wire costs for both 1G and 2G HTS are still too great to be economically feasible for such superconducting devices.

An analysis of using entomopathogenic nematodes against above-ground pests.

PubMed

Arthurs, S; Heinz, K M; Prasifka, J R

2004-08-01

Applications of entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae have traditionally been targeted against soil insects. Nonetheless, research over the last two decades highlights the potential of such agents against above-ground pests under certain circumstances. A general linear model was used to test for patterns in efficacy among 136 published trials with Steinernema carpocapsae Weiser, the most common species applied against foliar and other above-ground pests. The focus was on field and greenhouse assessments, rather than laboratory assays where relevant ecological barriers to infection are typically removed. The model showed differences in nematode treatment efficacy depending on the pests' target habitat (bore holes > cryptic foliage > exposed foliage) and trial location (greenhouse > field studies). Relative humidity and temperature during and up to 8 h post-application were also predicted to influence rates of nematode infection obtained. Conversely, spray adjuvants (both wetting agents and anti-desiccants) and nematode dosage applied (both concentration and use of consecutive applications 3-4 days apart) did not explain a significant amount of variance in nematode performance. With reference to case studies the model is used to discuss the relative importance of different factors on nematode efficacy and highlight priorities for workers considering using entomopathogenic nematodes to target pests in novel environments.

Niobium-germanium superconducting tapes for high-field magnet applications

NASA Technical Reports Server (NTRS)

Braginski, A. I.; Roland, G. W.; Daniel, M. R.; Woolam, J. A.

1977-01-01

A process of fabricating superconducting Nb3Ge tapes by chemical vapor deposition (CVD) has been developed and tapes up to 10 meters long fabricated. The typical properties achieved were: critical temperature T sub c = 20 K, upper critical field H sub c2 = 29 tesla at 4.2 K, and J sub c = 3 to 4 x 10 to the 8th power A m(-2) at 4.2 K, 18 tesla. The relative depression of T sub c and H sub c2 compared with the best thin film samples sputtered on sapphire was due to the presence of Nb5Ge3 second-phase particles used as flux pinning centers and to strains induced by thermal mixmatch with Hastelloy B tape substrates. A peculiar field dependence of flux pinning force that was observed in both CVD and sputtered Nb3Ge indicated a premature pin-breaking mechanism or a phase inhomogeneity. Directions of further optimization work were defined.

Light-efficient photography.

PubMed

Hasinoff, Samuel W; Kutulakos, Kiriakos N

2011-11-01

In this paper, we consider the problem of imaging a scene with a given depth of field at a given exposure level in the shortest amount of time possible. We show that by 1) collecting a sequence of photos and 2) controlling the aperture, focus, and exposure time of each photo individually, we can span the given depth of field in less total time than it takes to expose a single narrower-aperture photo. Using this as a starting point, we obtain two key results. First, for lenses with continuously variable apertures, we derive a closed-form solution for the globally optimal capture sequence, i.e., that collects light from the specified depth of field in the most efficient way possible. Second, for lenses with discrete apertures, we derive an integer programming problem whose solution is the optimal sequence. Our results are applicable to off-the-shelf cameras and typical photography conditions, and advocate the use of dense, wide-aperture photo sequences as a light-efficient alternative to single-shot, narrow-aperture photography.

Study on performance and flow field of an undershot cross-flow water turbine comprising different number of blades

NASA Astrophysics Data System (ADS)

Nishi, Yasuyuki; Hatano, Kentaro; Inagaki, Terumi

2017-10-01

Recently, small hydroelectric generators have gained attention as a further development in water turbine technology for ultra low head drops in open channels. The authors have evaluated the application of cross-flow water turbines in open channels as an undershot type after removing the casings and guide vanes to substantially simplify these water turbines. However, because undershot cross-flow water turbines are designed on the basis of cross-flow water turbine runners used in typical pipelines, it remains unclear whether the number of blades has an effect on the performance or flow fields. Thus, in this research, experiments and numerical analyses are employed to study the performance and flow fields of undershot cross-flow water turbines with varying number of blades. The findings show that the turbine output and torque are lower, the fluctuation is significantly higher, and the turbine efficiency is higher for runners with 8 blades as opposed to those with 24 blades.

Prediction of far-field wind turbine noise propagation with parabolic equation.

PubMed

Lee, Seongkyu; Lee, Dongjai; Honhoff, Saskia

2016-08-01

Sound propagation of wind farms is typically simulated by the use of engineering tools that are neglecting some atmospheric conditions and terrain effects. Wind and temperature profiles, however, can affect the propagation of sound and thus the perceived sound in the far field. A better understanding and application of those effects would allow a more optimized farm operation towards meeting noise regulations and optimizing energy yield. This paper presents the parabolic equation (PE) model development for accurate wind turbine noise propagation. The model is validated against analytic solutions for a uniform sound speed profile, benchmark problems for nonuniform sound speed profiles, and field sound test data for real environmental acoustics. It is shown that PE provides good agreement with the measured data, except upwind propagation cases in which turbulence scattering is important. Finally, the PE model uses computational fluid dynamics results as input to accurately predict sound propagation for complex flows such as wake flows. It is demonstrated that wake flows significantly modify the sound propagation characteristics.

Optical fiber nanoprobe preparation for near-field optical microscopy by chemical etching under surface tension and capillary action.

PubMed

Mondal, Samir K; Mitra, Anupam; Singh, Nahar; Sarkar, S N; Kapur, Pawan

2009-10-26

We propose a technique of chemical etching for fabrication of near perfect optical fiber nanoprobe (NNP). It uses photosensitive single mode optical fiber to etch in hydro fluoric (HF) acid solution. The difference in etching rate for cladding and photosensitive core in HF acid solution creates capillary ring along core-cladding boundary under a given condition. The capillary ring is filled with acid solution due to surface tension and capillary action. Finally it creates near perfect symmetric tip at the apex of the fiber as the height of the acid level in capillary ring decreases while width of the ring increases with continuous etching. Typical tip features are short taper length (approximately 4 microm), large cone angle (approximately 38 degrees ), and small probe tip dimension (<100 nm). A finite difference time domain (FDTD) analysis is also presented to compare near field optics of the NNP with conventional nanoprobe (CNP). The probe may be ideal for near field optical imaging and sensor applications.

Efficacy of insecticide residues on adult Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) mortality and injury in apple and peach orchards.

PubMed

Leskey, Tracy C; Short, Brent D; Lee, Doo-Hyung

2014-07-01

The primary threat from Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) originates from populations continuously dispersing from and among wild and cultivated hosts, so many individuals may not be directly sprayed with insecticides. Limited information exists regarding field-based residual activity of insecticides for management of H. halys in tree fruit. Thus, we conducted field-based bioassays in apple and peach orchards to evaluate residual activity of insecticides commonly applied against H. halys. Adults used in these trials were collected from wild and cultivated hosts less than one week prior to testing to more accurately reflect the susceptibility of wild H. halys populations in the field throughout the season. Significantly higher mortality rates of Halyomorpha halys were observed early in the growing season, when overwintered adults were prevalent, compared with populations present later in the growing season that included new generation adults. Significantly higher mortality was recorded for adults exposed to fresh insecticide applications compared with three- and seven-day old residues. Typically, the addition of an adjuvant did not enhance efficacy or residual activity of insecticides. Significantly fewer injury sites were recorded on apples treated with dinotefuran and fenpropathrin compared with the untreated apples for all residue ages. Overwintered Halyomorpha halys populations are easier to kill with insecticide applications than the first and second generation which are present in the field during the mid- to late-season. Residual activity of nearly all insecticides decreased significantly three days after application and adjuvants generally did not increase residual activity. These factors should be considered in developing season-long programs for management of this invasive species in tree fruit. © 2013 Society of Chemical Industry.

Energy dissipation of composite multifilamentary superconductors for high-current ramp-field magnet applications

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

Gung, C.Y.

1993-01-01

Energy dissipation, which is also called AC loss, of a composite multifilamentary superconducting wire is one of the most fundamental concerns in building a stable superconducting magnet. Characterization and reduction of AC losses are especially important in designing a superconducting magnet for generating transient magnetic fields. The goal of this thesis is to improve the understanding of AC-loss properties of superconducting wires developed for high-current ramp-field magnet applications. The major tasks include: (1) building an advanced AC-loss measurement system, (2) measuring AC losses of superconducting wires under simulated pulse magnet operations, (3) developing an analytical model for explaining the newmore » AC-loss properties found in the experiment, and (4) developing a computational methodology for comparing AC losses of a superconducting wire with those of a cable for a superconducting pulse magnet. A new experimental system using an isothermal calorimetric method was designed and constructed to measure the absolute AC losses in a composite superconductor. This unique experimental setup is capable of measuring AC losses of a brittle Nb{sub 3}Sn wire carrying high AC current in-phase with a large-amplitude pulse magnetic field. Improvements of the accuracy and the efficiency of this method are discussed. Three different types of composite wire have been measured: a Nb{sub 3}Sn modified jelly-roll (MJR) internal-tin wire used in a prototype ohmic heating coil, a Nb{sub 3}Sn internal-tin wire developed for a fusion reactor ohmic heating coil, and a NbTi wire developed for the magnets in a particle accelerator. The cross sectional constructions of these wires represent typical commercial wires manufactured for pulse magnet applications.« less

The mean magnetic field of the sun: Observations at Stanford

NASA Technical Reports Server (NTRS)

Scherrer, P. H.; Wilcox, J. M.; Svalgaard, L.; Duvall, T. L., Jr.; Dittmer, P. H.; Gustafson, E. K.

1977-01-01

A solar telescope was built at Stanford University to study the organization and evolution of large-scale solar magnetic fields and velocities. The observations are made using a Babcock-type magnetograph which is connected to a 22.9 m vertical Littrow spectrograph. Sun-as-a-star integrated light measurements of the mean solar magnetic field were made daily since May 1975. The typical mean field magnitude is about 0.15 gauss with typical measurement error less than 0.05 gauss. The mean field polarity pattern is essentially identical to the interplanetary magnetic field sector structure (seen near the earth with a 4 day lag). The differences in the observed structures can be understood in terms of a warped current sheet model.

Scanning magnetic tunnel junction microscope for high-resolution imaging of remanent magnetization fields

NASA Astrophysics Data System (ADS)

Lima, E. A.; Bruno, A. C.; Carvalho, H. R.; Weiss, B. P.

2014-10-01

Scanning magnetic microscopy is a new methodology for mapping magnetic fields with high spatial resolution and field sensitivity. An important goal has been to develop high-performance instruments that do not require cryogenic technology due to its high cost, complexity, and limitation on sensor-to-sample distance. Here we report the development of a low-cost scanning magnetic microscope based on commercial room-temperature magnetic tunnel junction (MTJ) sensors that typically achieves spatial resolution better than 7 µm. By comparing different bias and detection schemes, optimal performance was obtained when biasing the MTJ sensor with a modulated current at 1.0 kHz in a Wheatstone bridge configuration while using a lock-in amplifier in conjunction with a low-noise custom-made preamplifier. A precision horizontal (x-y) scanning stage comprising two coupled nanopositioners controls the position of the sample and a linear actuator adjusts the sensor-to-sample distance. We obtained magnetic field sensitivities better than 150 nT/Hz1/2 between 0.1 and 10 Hz, which is a critical frequency range for scanning magnetic microscopy. This corresponds to a magnetic moment sensitivity of 10-14 A m2, a factor of 100 better than achievable with typical commercial superconducting moment magnetometers. It also represents an improvement in sensitivity by a factor between 10 and 30 compared to similar scanning MTJ microscopes based on conventional bias-detection schemes. To demonstrate the capabilities of the instrument, two polished thin sections of representative geological samples were scanned along with a synthetic sample containing magnetic microparticles. The instrument is usable for a diversity of applications that require mapping of samples at room temperature to preserve magnetic properties or viability, including paleomagnetism and rock magnetism, nondestructive evaluation of materials, and biological assays.

Rapid, topology-based particle tracking for high-resolution measurements of large complex 3D motion fields.

PubMed

Patel, Mohak; Leggett, Susan E; Landauer, Alexander K; Wong, Ian Y; Franck, Christian

2018-04-03

Spatiotemporal tracking of tracer particles or objects of interest can reveal localized behaviors in biological and physical systems. However, existing tracking algorithms are most effective for relatively low numbers of particles that undergo displacements smaller than their typical interparticle separation distance. Here, we demonstrate a single particle tracking algorithm to reconstruct large complex motion fields with large particle numbers, orders of magnitude larger than previously tractably resolvable, thus opening the door for attaining very high Nyquist spatial frequency motion recovery in the images. Our key innovations are feature vectors that encode nearest neighbor positions, a rigorous outlier removal scheme, and an iterative deformation warping scheme. We test this technique for its accuracy and computational efficacy using synthetically and experimentally generated 3D particle images, including non-affine deformation fields in soft materials, complex fluid flows, and cell-generated deformations. We augment this algorithm with additional particle information (e.g., color, size, or shape) to further enhance tracking accuracy for high gradient and large displacement fields. These applications demonstrate that this versatile technique can rapidly track unprecedented numbers of particles to resolve large and complex motion fields in 2D and 3D images, particularly when spatial correlations exist.

A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms

NASA Astrophysics Data System (ADS)

Huo, Ming-Xia; Nie, Wei; Hutchinson, David A. W.; Kwek, Leong Chuan

2014-08-01

Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a ``hairline'' solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms.

PubMed

Huo, Ming-Xia; Nie, Wei; Hutchinson, David A W; Kwek, Leong Chuan

2014-08-08

Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a "hairline" solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

Electric-field induced spin accumulation in the Landau level states of topological insulator thin films

NASA Astrophysics Data System (ADS)

Siu, Zhuo Bin; Chowdhury, Debashree; Basu, Banasri; Jalil, Mansoor B. A.

2017-08-01

A topological insulator (TI) thin film differs from the more typically studied thick TI system in that the former has both a top and a bottom surface where the states localized at both surfaces can couple to one other across the finite thickness. An out-of-plane magnetic field leads to the formation of discrete Landau level states in the system, whereas an in-plane magnetization breaks the angular momentum symmetry of the system. In this work, we study the spin accumulation induced by the application of an in-plane electric field to the TI thin film system where the Landau level states and inter-surface coupling are simultaneously present. We show, via Kubo formula calculations, that the in-plane spin accumulation perpendicular to the magnetization due to the electric field vanishes for a TI thin film with symmetric top and bottom surfaces. A finite in-plane spin accumulation perpendicular to both the electric field and magnetization emerges upon applying either a differential magnetization coupling or a potential difference between the two film surfaces. This spin accumulation results from the breaking of the antisymmetry of the spin accumulation around the k-space equal-energy contours.

Shaping complex microwave fields in reverberating media with binary tunable metasurfaces

PubMed Central

Kaina, Nadège; Dupré, Matthieu; Lerosey, Geoffroy; Fink, Mathias

2014-01-01

In this article we propose to use electronically tunable metasurfaces as spatial microwave modulators. We demonstrate that like spatial light modulators, which have been recently proved to be ideal tools for controlling light propagation through multiple scattering media, spatial microwave modulators can efficiently shape in a passive way complex existing microwave fields in reverberating environments with a non-coherent energy feedback. Unlike in free space, we establish that a binary-only phase state tunable metasurface allows a very good control over the waves, owing to the random nature of the electromagnetic fields in these complex media. We prove in an everyday reverberating medium, that is, a typical office room, that a small spatial microwave modulator placed on the walls can passively increase the wireless transmission between two antennas by an order of magnitude, or on the contrary completely cancel it. Interestingly and contrary to free space, we show that this results in an isotropic shaped microwave field around the receiving antenna, which we attribute again to the reverberant nature of the propagation medium. We expect that spatial microwave modulators will be interesting tools for fundamental physics and will have applications in the field of wireless communications. PMID:25331498

Studies of the field-of-view resolution tradeoff in virtual-reality systems

NASA Technical Reports Server (NTRS)

Piantanida, Thomas P.; Boman, Duane; Larimer, James; Gille, Jennifer; Reed, Charles

1992-01-01

Most virtual-reality systems use LCD-based displays that achieve a large field-of-view at the expense of resolution. A typical display will consist of approximately 86,000 pixels uniformly distributed over an 80-degree by 60-degree image. Thus, each pixel subtends about 13 minutes of arc at the retina; about the same as the resolvable features of the 20/200 line of a Snellen Eye Chart. The low resolution of LCD-based systems limits task performance in some applications. We have examined target-detection performance in a low-resolution virtual world. Our synthesized three-dimensional virtual worlds consisted of target objects that could be positioned at a fixed distance from the viewer, but at random azimuth and constrained elevation. A virtual world could be bounded by chromatic walls or by wire-frame, or it could be unbounded. Viewers scanned these worlds and indicated by appropriate gestures when they had detected the target object. By manipulating the viewer's field size and the chromatic and luminance contrast of annuli surrounding the field-of-view, we were able to assess the effect of field size on the detection of virtual objects in low-resolution synthetic worlds.

Higher-order mode rf guns

NASA Astrophysics Data System (ADS)

Lewellen, John W.

2001-04-01

Traditional photocathode rf gun design is based around the use of TM0,1,0-mode cavities. This is typically done in the interest of obtaining the highest possible gradient per unit supplied rf power and for historical reasons. In a multicell, aperture-coupled photoinjector, however, the gun as a whole is produced from strongly coupled cavities oscillating in a π mode. This design requires very careful preparation and tuning, as the field balance and resonant frequencies are easily disturbed. Side-coupled designs are often avoided because of the dipole modes introduced into the cavity fields. This paper proposes the use of a single higher-order mode rf cavity in order to generate the desired on-axis fields. It is shown that the field experienced by a beam in a higher-order mode rf gun is initially very similar to traditional 1.5- or 2.5-cell π-mode gun fields, and projected performance in terms of beam quality is also comparable. The new design has the advantages of much greater ease of fabrication, immunity from coupled-cell effects, and simpler tuning procedures. Because of the gun geometry, the possibility also exists for improved temperature stabilization and cooling for high duty-cycle applications.

Superconductivity in two-dimensional NbSe2 field effect transistors

NASA Astrophysics Data System (ADS)

El-Bana, Mohammed S.; Wolverson, Daniel; Russo, Saverio; Balakrishnan, Geetha; Mck Paul, Don; Bending, Simon J.

2013-12-01

We describe investigations of superconductivity in few molecular layer NbSe2 field effect transistors. While devices fabricated from NbSe2 flakes less than eight molecular layers thick did not conduct, thicker flakes were superconducting with an onset Tc that was only slightly depressed from the bulk value for 2H-NbSe2 (7.2 K). The resistance typically showed a small, sharp high temperature transition followed by one or more broader transitions which usually ended in a wide tail to zero resistance at low temperatures. We speculate that these multiple resistive transitions are related to disorder in the layer stacking. The behavior of several flakes has been characterized as a function of temperature, applied field and back-gate voltage. We find that the conductance in the normal state and transition temperature depend weakly on the gate voltage, with both conductivity and Tc decreasing as the electron concentration is increased. The application of a perpendicular magnetic field allows the evolution of different resistive transitions to be tracked and values of the zero temperature upper critical field, Hc2(0), and coherence length, ξ(0), to be independently estimated. Our results are analyzed in terms of available theories for these phenomena.

Scaling and dimensional analysis of acoustic streaming jets

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

Moudjed, B.; Botton, V.; Henry, D.

2014-09-15

This paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of acoustic streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with amore » review of the former experimental investigations using similar configurations. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.« less

Evaluating Water Budget Closure Across Spatial Scales: An Observational Approach through Texas Water Observatory

NASA Astrophysics Data System (ADS)

Gaur, N.; Jaimes, A.; Vaughan, S.; Morgan, C.; Moore, G. W.; Miller, G. R.; Everett, M. E.; Lawing, M.; Mohanty, B.

2017-12-01

Applications varying from improving water conservation practices at the field scale to predicting global hydrology under a changing climate depend upon our ability to achieve water budget closure. 1) Prevalent heterogeneity in soils, geology and land-cover, 2) uncertainties in observations and 3) space-time scales of our control volume and available data are the main factors affecting the percentage of water budget closure that we can achieve. The Texas Water Observatory presents a unique opportunity to observe the major components of the water cycle (namely precipitation, evapotranspiration, root zone soil moisture, streamflow and groundwater) in varying eco-hydrological regions representative of the lower Brazos River basin at multiple scales. The soils in these regions comprise of heavy clays that swell and shrink to create complex preferential pathways in the sub-surface, thus, making the hydrology in this region difficult to quantify. This work evaluates the water budget of the region by varying the control volume in terms of 3 temporal (weekly, monthly and seasonal) and 3 different spatial scales. The spatial scales are 1) Point scale - that is typical for process understanding of water dynamics, 2) Eddy Covariance footprint scale - that is typical of most eco-hydrological applications at the field scale and, 3) Satellite footprint scale- that is typically used in regional and global hydrological analysis. We employed a simple water balance model to evaluate the water budget at all scales. The point scale water budget was assessed using direct observations from hydro-geo-thematically located observation locations within different eddy covariance footprints. At the eddy covariance footprint scale, the sub-surface of each eddy covariance footprint was intensively characterized using electromagnetic induction (EM 38) and the resultant data was used to calculate the inter-point variability to upscale the sub-surface storage while the satellite scale water budget was evaluated using SMAP satellite observations supplemented with reanalysis products. At the point scale, we found differences in sub-surface storage in the same land-cover depending on the landscape position of the observation point while land-cover significantly affected water budget at the larger scales.

Magnetotransport in magnetic nanostructures

NASA Astrophysics Data System (ADS)

Panchula, Alex F.

The unifying theme of this dissertation is the exploration of novel magnetic thin film materials to improve our understanding of spin-dependent transport in such materials, especially with regard to their use in the nascent field of spin based devices. Such devices, which rely on controlling the electron's spin rather than its charge as in conventional micro-electronics, may be important for applications in sensing, memory and computation. This dissertation covers research performed at the IBM Almaden Research Center between 2000 and 2003. One class of spin-based devices are magnetic tunnel junctions (MTJs), which display large changes in resistance in small magnetic fields. This tunneling magnetoresistance (TMR) is derived from changes in the relative alignment of the magnetic moments of thin ferromagnetic layers which are separated by thin insulating layers. The tunneling current spin polarization (TSP) determines the magnitude of the TMR. For typical transition-metal ferromagnets and their alloys the TSP is ˜50% although it is anticipated that half-metals should display nearly 100%. Confirming theoretical predictions, MTJs with electrodes of magnetite and a conventional ferromagnet such as a CoFe alloy, display an inverted TMR, consistent with negatively spin polarized magnetite electrodes. However, the magnitude of TSP of -48% at low temperatures, is not much larger than that exhibited by conventional 3d transition metal ferromagnets. At high temperatures, transport through the MTJ is dominated by tunneling across the alumina tunnel barrier, while at low temperatures the bulk properties of the magnetite dominates at low bias voltage. Another class of half-metals, the semi-heuslers exhibit low TSP, most likely due to surface disorder and, as revealed in this work, the possible formation of MnSb. The MnSb alloys studied in MTJs are found to behave as typical ferromagnets with a small positive TMR. Also considered are MTJs whose barriers are comprised of the wide band-gap semiconductors, ZnSe and Cr2O3. These low barrier height materials show typical tunneling behavior, although the TMR is lower than found for wide-gap insulators. Finally, the development of a high precision SQUID based voltmeter for application to low resistance devices with the current perpendicular to the plane of the materials is outlined.

Concept, design and analysis of a large format autostereoscopic display system

NASA Astrophysics Data System (ADS)

Knocke, F.; de Jongh, R.; Frömel, M.

2005-09-01

Autostereoscopic display devices with large visual field are of importance in a number of applications such as computer aided design projects, technical education, and military command systems. Typical requirements for such systems are, aside from the large visual field, a large viewing zone, a high level of image brightness, and an extended depth of field. Additional appliances such as specialized eyeglasses or head-trackers are disadvantageous for the aforementioned applications. We report on the design and prototyping of an autostereoscopic display system on the basis of projection-type one-step unidirectional holography. The prototype consists of a hologram holder, an illumination unit, and a special direction-selective screen. Reconstruction light is provided by a 2W frequency-doubled Nd:YVO4 laser. The production of stereoscopic hologram stripes on photopolymer is carried out on a special origination setup. The prototype has a screen size of 180cm × 90cm and provides a visual field of 29° when viewed from 3.6 meters. Due to the coherent reconstruction, a depth of field of several meters is achievable. Up to 18 hologram stripes can be arranged on the holder to permit a rapid switch between a series of motifs or views. Both computer generated image sequences and digital camera photos may serve as input frames. However, a comprehensive pre-distortion must be performed in order to account for optical distortion and several other geometrical factors. The corresponding computations are briefly summarized below. The performance of the system is analyzed, aspects of beam-shaping and mechanical design are discussed and photographs of early reconstructions are presented.

Demonstration Report, Munitions Management Projects, ESTCP Project MR-200809, ALLTEM Multi-Axis Electromagnetic Induction System Demonstration and Validation, Aberdeen Proving Ground Standardized UXO Technology Demonstration Site, Version 1.0

DTIC Science & Technology

2011-11-17

to emulate typical impact area conditions. The Open Field area is now divided into four subareas: Legacy, Indirect fire, Direct fire, and Challenge...that could be typically found at an impact area of an indirect fire weapons range. These are 81 mm and 60 mm mortars and 105 ALLTEM APG...munitions. • Open field (direct fire) The direct fire subarea contains only three munition types that could be typically found at an impact area of

Electric fields induced in the human body by time-varying magnetic field gradients in MRI: numerical calculations and correlation analysis.

PubMed

Bencsik, Martin; Bowtell, Richard; Bowley, Roger

2007-05-07

The spatial distributions of the electric fields induced in the human body by switched magnetic field gradients in MRI have been calculated numerically using the commercial software package, MAFIA, and the three-dimensional, HUGO body model that comprises 31 different tissue types. The variation of |J|, |E| and |B| resulting from exposure of the body model to magnetic fields generated by typical whole-body x-, y- and z-gradient coils has been analysed for three different body positions (head-, heart- and hips-centred). The magnetic field varied at 1 kHz, so as to produce a rate of change of gradient of 100 T m(-1) s(-1) at the centre of each coil. A highly heterogeneous pattern of induced electric field and current density was found to result from the smoothly varying magnetic field in all cases, with the largest induced electric fields resulting from application of the y-gradient, in agreement with previous studies. By applying simple statistical analysis to electromagnetic quantities within axial planes of the body model, it is shown that the induced electric field is strongly correlated to the local value of resistivity, and the induced current density exhibits even stronger correlation with the local conductivity. The local values of the switched magnetic field are however shown to bear little relation to the local values of the induced electric field or current density.

Exploring EBW conversion physics with applications to NSTX-U

NASA Astrophysics Data System (ADS)

Lopez, N. A.; Ram, A. K.; Poli, F. M.; Du Toit, E. J.

2017-10-01

Radiofrequency waves are commonly used on traditional tokamaks to assist plasma formation and to provide non-inductive heating and current drive (NI H&CD). Their applicability to spherical tokamaks (STs), however, is complicated by the latter's comparatively high densities and low field strengths. Electron Bernstein waves (EBW) are attractive for NI H&CD on STs because they do not experience a density cutoff and they damp strongly in the vicinity of cyclotron harmonics, even at low temperatures typical of startup. The excitation of EBWs using vacuum-launched electromagnetic waves requires a mode conversion that is highly sensitive to the choice of launch polarization and to local plasma parameters. Common theoretical models employ a 1D slab geometry to study such conversion processes; however, these models may be insufficient to describe the EBW conversion physics in STs, in which equilibria are typically strongly-shaped with large magnetic shear. We report our progress on a theoretical study of EBW conversion physics that emphasizes the inherent idiosyncrasies of the ST equilibrium. Additionally, using a recently developed OD2V kinetic model along with GENRAY simulations, we assess the EBW NI H&CD on NSTX-U using the OXB startup technique that has been developed on MAST. We then make recommendations regarding its implementation in future experimental campaigns.

Energy coupling in short pulse laser solid interactions and its impact for space debris removal.

PubMed

Neely, David; Allott, Ric; Bingham, Bob; Collier, John; Greenhalgh, Justin; Michaelis, Max; Phillips, Jonathan; Phipps, Claude R; McKenna, Paul

2014-11-01

Significant advances have been made over the last decade to improve the performance, efficiency, and contrast of high peak and average power laser systems, driven by their use in a wide variety of fields, from the industrial to the scientific. As the contrast of the lasers has improved, interactions with contrasts of 10¹² are now routinely undertaken. At such high contrasts, there is negligible preplasma formation and the ionized surface layer created by subpicosecond-duration pulses typically forms a highly reflective "plasma mirror" capable of reflecting between 70% and 90% of the incident energy. Although such interactions are of significant interest for applications such as harmonic source production and to enable the underlying physics to be studied, their low absorption can limit their usefulness for applications such as space debris removal.

Toward more versatile and intuitive cortical brain-machine interfaces.

PubMed

Andersen, Richard A; Kellis, Spencer; Klaes, Christian; Aflalo, Tyson

2014-09-22

Brain-machine interfaces have great potential for the development of neuroprosthetic applications to assist patients suffering from brain injury or neurodegenerative disease. One type of brain-machine interface is a cortical motor prosthetic, which is used to assist paralyzed subjects. Motor prosthetics to date have typically used the motor cortex as a source of neural signals for controlling external devices. The review will focus on several new topics in the arena of cortical prosthetics. These include using: recordings from cortical areas outside motor cortex; local field potentials as a source of recorded signals; somatosensory feedback for more dexterous control of robotics; and new decoding methods that work in concert to form an ecology of decode algorithms. These new advances promise to greatly accelerate the applicability and ease of operation of motor prosthetics. Copyright © 2014 Elsevier Ltd. All rights reserved.

TOPICAL REVIEW: Tribology of dental materials: a review

NASA Astrophysics Data System (ADS)

Zhou, Z. R.; Zheng, J.

2008-06-01

The application of tribology in dentistry is a growing and rapidly expanding field. Intensive research has been conducted to develop an understanding of dental tribology for successful design and selection of artificial dental materials. In this paper, the anatomy and function of human teeth is presented in brief, three types of current artificial dental materials are summarized, and their advantages and disadvantages, as well as typical clinical applications, are compared based on the literature. Possible tribological damage of tooth structure, which is induced by complex interfacial motion, and friction-wear test methods are reported. According to results obtained by the authors and from the literature, the main progress in the area of dental tribology on both natural teeth and artificial dental materials is reviewed. Problems and challenges are discussed and future research directions for dental tribology are recommended.

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

Nekkab, M., E-mail: mohammed-nekkab@yahoo.com; LESIMS laboratory, Physics Department, Faculty of Sciences, University of Setif 1, 19000 Setif; Kahoul, A.

The analytical methods based on X-ray fluorescence are advantageous for practical applications in a variety of fields including atomic physics, X-ray fluorescence surface chemical analysis and medical research and so the accurate fluorescence yields (ω{sub K}) are required for these applications. In this contribution we report a new parameters for calculation of K-shell fluorescence yields (ω{sub K}) of elements in the range of 11≤Z≤30. The experimental data are interpolated by using the famous analytical function (ω{sub k}/(1−ω{sub k})){sup 1/q} (were q=3, 3.5 and 4) vs Z to deduce the empirical K-shell fluorescence yields. A comparison is made between the resultsmore » of the procedures followed here and those theoretical and other semi-empirical fluorescence yield values. Reasonable agreement was typically obtained between our result and other works.« less

Iron Containing Metal-Organic Frameworks: Structure, Synthesis, and Applications in Environmental Remediation.

PubMed

Liu, Xiaocheng; Zhou, Yaoyu; Zhang, Jiachao; Tang, Lin; Luo, Lin; Zeng, Guangming

2017-06-21

Metal-organic frameworks (MOFs) with Fe content are gradually developing into an independent branch in environmental remediation, requiring economical, effective, low-toxicity strategies to the complete procedure. In this review, recent advancements in the structure, synthesis, and environmental application focusing on the mechanism are presented. The unique structure of novel design proposed specific characteristics of different iron-containing MOFs with potential innovation. Synthesis of typical MILs, NH 2 -MILs and MILs based materials reveal the basis and defect of the current method, indicating the optimal means for the actual requirements. The adsorption of various contamination with multiple interaction as well as the catalytic degradation over radicals or electron-hole pairs are reviewed. This review implied considerable prospects of iron-containing MOFs in the field of environment and a more comprehensive cognition into the challenges and potential improvement.

Design of an FMCW radar baseband signal processing system for automotive application.

PubMed

Lin, Jau-Jr; Li, Yuan-Ping; Hsu, Wei-Chiang; Lee, Ta-Sung

2016-01-01

For a typical FMCW automotive radar system, a new design of baseband signal processing architecture and algorithms is proposed to overcome the ghost targets and overlapping problems in the multi-target detection scenario. To satisfy the short measurement time constraint without increasing the RF front-end loading, a three-segment waveform with different slopes is utilized. By introducing a new pairing mechanism and a spatial filter design algorithm, the proposed detection architecture not only provides high accuracy and reliability, but also requires low pairing time and computational loading. This proposed baseband signal processing architecture and algorithms balance the performance and complexity, and are suitable to be implemented in a real automotive radar system. Field measurement results demonstrate that the proposed automotive radar signal processing system can perform well in a realistic application scenario.

Calculation of K-shell fluorescence yields for low-Z elements

NASA Astrophysics Data System (ADS)

Nekkab, M.; Kahoul, A.; Deghfel, B.; Aylikci, N. Küp; Aylikçi, V.

2015-03-01

The analytical methods based on X-ray fluorescence are advantageous for practical applications in a variety of fields including atomic physics, X-ray fluorescence surface chemical analysis and medical research and so the accurate fluorescence yields (ωK) are required for these applications. In this contribution we report a new parameters for calculation of K-shell fluorescence yields (ωK) of elements in the range of 11≤Z≤30. The experimental data are interpolated by using the famous analytical function (ωk/(1 -ωk)) 1 /q (were q=3, 3.5 and 4) vs Z to deduce the empirical K-shell fluorescence yields. A comparison is made between the results of the procedures followed here and those theoretical and other semi-empirical fluorescence yield values. Reasonable agreement was typically obtained between our result and other works.

Laser vibration sensing at Fraunhofer IOSB: review and applications

NASA Astrophysics Data System (ADS)

Lutzmann, Peter; Göhler, Benjamin; Hill, Chris A.; van Putten, Frank

2017-03-01

Laser vibrometry based on coherent detection allows noncontact measurements of small-amplitude vibration characteristics of objects. This technique, commonly using the Doppler effect, offers high potential for short-range civil applications and for medium- or long-range applications in defense and security. Most commercially available laser Doppler vibrometers are for short ranges (up to a few tens of meters) and use a single beam from a low-power HeNe laser source (λ=633 nm). Medium- or long-range applications need higher laser output power, and thus, appropriate vibrometers typically operate at 1.5, 2, or 10.6 μm to meet the laser safety regulations. Spatially resolved vibrational information can be obtained from an object by using scanning laser vibrometers. To reduce measuring time and to measure transient object movements and vibrational mode structures of objects, several approaches to multibeam laser Doppler vibrometry have been developed, and some of them are already commercially available for short ranges. We focus on applications in the field of defense and security, such as target classification and identification, including camouflaged or partly concealed targets, and the detection of buried land mines. Examples of civil medium-range applications are also given.

Estimating pathway-specific contributions to biodegradation in aquifers based on dual isotope analysis: theoretical analysis and reactive transport simulations.

PubMed

Centler, Florian; Heße, Falk; Thullner, Martin

2013-09-01

At field sites with varying redox conditions, different redox-specific microbial degradation pathways contribute to total contaminant degradation. The identification of pathway-specific contributions to total contaminant removal is of high practical relevance, yet difficult to achieve with current methods. Current stable-isotope-fractionation-based techniques focus on the identification of dominant biodegradation pathways under constant environmental conditions. We present an approach based on dual stable isotope data to estimate the individual contributions of two redox-specific pathways. We apply this approach to carbon and hydrogen isotope data obtained from reactive transport simulations of an organic contaminant plume in a two-dimensional aquifer cross section to test the applicability of the method. To take aspects typically encountered at field sites into account, additional simulations addressed the effects of transverse mixing, diffusion-induced stable-isotope fractionation, heterogeneities in the flow field, and mixing in sampling wells on isotope-based estimates for aerobic and anaerobic pathway contributions to total contaminant biodegradation. Results confirm the general applicability of the presented estimation method which is most accurate along the plume core and less accurate towards the fringe where flow paths receive contaminant mass and associated isotope signatures from the core by transverse dispersion. The presented method complements the stable-isotope-fractionation-based analysis toolbox. At field sites with varying redox conditions, it provides a means to identify the relative importance of individual, redox-specific degradation pathways. © 2013.

A new seamless, smooth, interior, absorptive finishing system

NASA Astrophysics Data System (ADS)

D'Antonio, Peter

2003-10-01

Government architecture typically employs classic forms of vaults, domes and other focusing or reflective shapes, usually created with hard materials like concrete and plaster. The use of conventional porous absorption is typically rejected as an acoustical surface material for aesthetic reasons. Hence, many of these new and existing facilities have compromised speech intelligibility and music quality. Acousticians have sought a field-applied, absorptive finishing system that resembles a smooth plaster or painted drywall surface, since the dawn of architectural acoustics. Some success has been achieved using sprayed cellulose or cementitious materials, but surface smoothness has been a challenge. A new approach utilizing a thin microporous layer of mineral particles applied over a mineral wool panel will be described. This material can be applied to almost any shape surface, internally pigmented to match almost any color and renovated. Because of these unique characteristics the new seamless, absorptive, finishing system is being specified for many new and renovated spaces. Application examples will be presented.

Reducing Field Distortion in Magnetic Resonance Imaging

NASA Technical Reports Server (NTRS)

Eom, Byeong Ho; Penanen, Konstantin; Hahn, Inseob

2010-01-01

A concept for a magnetic resonance imaging (MRI) system that would utilize a relatively weak magnetic field provides for several design features that differ significantly from the corresponding features of conventional MRI systems. Notable among these features are a magnetic-field configuration that reduces (relative to the conventional configuration) distortion and blurring of the image, the use of a superconducting quantum interference device (SQUID) magnetometer as the detector, and an imaging procedure suited for the unconventional field configuration and sensor. In a typical application of MRI, a radio-frequency pulse is used to excite precession of the magnetic moments of protons in an applied magnetic field, and the decaying precession is detected for a short time following the pulse. The precession occurs at a resonance frequency proportional to the strengths of the magnetic field and the proton magnetic moment. The magnetic field is configured to vary with position in a known way; hence, by virtue of the aforesaid proportionality, the resonance frequency varies with position in a known way. In other words, position is encoded as resonance frequency. MRI using magnetic fields weaker than those of conventional MRI offers several advantages, including cheaper and smaller equipment, greater compatibility with metallic objects, and higher image quality because of low susceptibility distortion and enhanced spin-lattice-relaxation- time contrast. SQUID MRI is being developed into a practical MRI method for applied magnetic flux densities of the order of only 100 T

Effect of atomic layer deposition temperature on the performance of top-down ZnO nanowire transistors

PubMed Central

2014-01-01

This paper studies the effect of atomic layer deposition (ALD) temperature on the performance of top-down ZnO nanowire transistors. Electrical characteristics are presented for 10-μm ZnO nanowire field-effect transistors (FETs) and for deposition temperatures in the range 120°C to 210°C. Well-behaved transistor output characteristics are obtained for all deposition temperatures. It is shown that the maximum field-effect mobility occurs for an ALD temperature of 190°C. This maximum field-effect mobility corresponds with a maximum Hall effect bulk mobility and with a ZnO film that is stoichiometric. The optimized transistors have a field-effect mobility of 10 cm2/V.s, which is approximately ten times higher than can typically be achieved in thin-film amorphous silicon transistors. Furthermore, simulations indicate that the drain current and field-effect mobility extraction are limited by the contact resistance. When the effects of contact resistance are de-embedded, a field-effect mobility of 129 cm2/V.s is obtained. This excellent result demonstrates the promise of top-down ZnO nanowire technology for a wide variety of applications such as high-performance thin-film electronics, flexible electronics, and biosensing. PMID:25276107

Design and performance of subgrade biogeochemical reactors.

PubMed

Gamlin, Jeff; Downey, Doug; Shearer, Brad; Favara, Paul

2017-12-15

Subgrade biogeochemical reactors (SBGRs), also commonly referred to as in situ bioreactors, are a unique technology for treatment of contaminant source areas and groundwater plume hot spots. SBGRs have most commonly been configured for enhanced reductive dechlorination (ERD) applications for chlorinated solvent treatment. However, they have also been designed for other contaminant classes using alternative treatment media. The SBGR technology typically consists of removal of contaminated soil via excavation or large-diameter augers, and backfill of the soil void with gravel and treatment amendments tailored to the target contaminant(s). In most cases SBGRs include installation of infiltration piping and a low-flow pumping system (typically solar-powered) to recirculate contaminated groundwater through the SBGR for treatment. SBGRs have been constructed in multiple configurations, including designs capable of meeting limited access restrictions at heavily industrialized sites, and at sites with restrictions on surface disturbance due to sensitive species or habitat issues. Typical performance results for ERD applications include 85 to 90 percent total molar reduction of chlorinated volatile organic compounds (CVOCs) near the SBGR and rapid clean-up of adjacent dissolved contaminant source areas. Based on a review of the literature and CH2M's field-scale results from over a dozen SBGRs with a least one year of performance data, important site-specific design considerations include: 1) hydraulic residence time should be long enough for sufficient treatment but not too long to create depressed pH and stagnant conditions (e.g., typically between 10 and 60 days), 2) reactor material should balance appropriate organic mulch as optimal bacterial growth media along with other organic additives that provide bioavailable organic carbon, 3) a variety of native bacteria are important to the treatment process, and 4) biologically mediated generation of iron sulfides along with addition of iron pyrite sands as an abiotic polishing step within the reactor has been observed to be an efficient treatment train for chlorinated solvent sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

TU-F-CAMPUS-T-04: An Evaluation of Out-Of-Field Doses for Electron Beams From Modern Varian and Elekta Linear Accelerators

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

Cardenas, C; Nitsch, P; Kudchadker, R

2015-06-15

Purpose: Accurately determining out-of-field doses when using electron beam radiotherapy is of importance when treating pregnant patients or patients with implanted electronic devices. Scattered doses outside of the applicator field in electron beams have not been broadly investigated, especially since manufacturers have taken different approaches in applicator designs. Methods: In this study, doses outside of the applicator field were measured for electron beams produced by a 10×10 applicator on two Varian 21iXs operating at 6, 9, 12, 16, and 20 MeV, a Varian TrueBeam operating at 6, 9, 12, 16, and 20 MeV, and an Elekta Versa HD operating atmore » 6, 9, 12 and 15 MeV. Peripheral dose profiles and percent depth doses were measured in a Wellhofer water phantom at 100 cm SSD with a Farmer ion chamber. Doses were compared to peripheral photon doses from AAPM’s Task Group #36 report. Results: Doses were highest for the highest electron energies. Doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. Substantial dose differences were observed between different accelerators; the Elekta accelerator had much higher doses than any Varian unit examined. Surprisingly, doses were often similar to, and could be much higher than, doses from photon therapy. Doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. Conclusion: The results of this study indicate that proper shielding may be very important when utilizing electron beams, particularly on a Versa HD, while treating pregnant patients or those with implanted electronic devices. Applying a water equivalent bolus of Emax(MeV)/4 thickness (cm) on the patient would reduce fetal dose drastically for all clinical energies and is a practical solution to manage the potentially high peripheral doses seen from modern electron beams. Funding from NIH Grant number: #CA180803.« less

Towards a theoretical clarification of biomimetics using conceptual tools from engineering design.

PubMed

Drack, M; Limpinsel, M; de Bruyn, G; Nebelsick, J H; Betz, O

2017-12-13

Many successful examples of biomimetic products are available, and most research efforts in this emerging field are directed towards the development of specific applications. The theoretical and conceptual underpinnings of the knowledge transfer between biologists, engineers and architects are, however, poorly investigated. The present article addresses this gap. We use a 'technomorphic' approach, i.e. the application of conceptual tools derived from engineering design, to better understand the processes operating during a typical biomimetic research project. This helps to elucidate the formal connections between functions, working principles and constructions (in a broad sense)-because the 'form-function-relationship' is a recurring issue in biology and engineering. The presented schema also serves as a conceptual framework that can be implemented for future biomimetic projects. The concepts of 'function' and 'working principle' are identified as the core elements in the biomimetic knowledge transfer towards applications. This schema not only facilitates the development of a common language in the emerging science of biomimetics, but also promotes the interdisciplinary dialogue among its subdisciplines.

Femtosecond Laser Fabrication of Monolithically Integrated Microfluidic Sensors in Glass

PubMed Central

He, Fei; Liao, Yang; Lin, Jintian; Song, Jiangxin; Qiao, Lingling; Cheng, Ya; Sugioka, Koji

2014-01-01

Femtosecond lasers have revolutionized the processing of materials, since their ultrashort pulse width and extremely high peak intensity allows high-quality micro- and nanofabrication of three-dimensional (3D) structures. This unique capability opens up a new route for fabrication of microfluidic sensors for biochemical applications. The present paper presents a comprehensive review of recent advancements in femtosecond laser processing of glass for a variety of microfluidic sensor applications. These include 3D integration of micro-/nanofluidic, optofluidic, electrofluidic, surface-enhanced Raman-scattering devices, in addition to fabrication of devices for microfluidic bioassays and lab-on-fiber sensors. This paper describes the unique characteristics of femtosecond laser processing and the basic concepts involved in femtosecond laser direct writing. Advanced spatiotemporal beam shaping methods are also discussed. Typical examples of microfluidic sensors fabricated using femtosecond lasers are then highlighted, and their applications in chemical and biological sensing are described. Finally, a summary of the technology is given and the outlook for further developments in this field is considered. PMID:25330047

Typical Applications of Airborne LIDAR Technolagy in Geological Investigation

NASA Astrophysics Data System (ADS)

Zheng, X.; Xiao, C.

2018-05-01

The technology of airborne light detection and ranging (LiDAR), also referred to as Airborne Laser Scanning, is widely used for high-resolution topographic data acquisition (even under forest cover) with sub-meter planimetric and vertical accuracy. This contribution constructs the real digital terrain model to provide the direct observation data for the landscape analysis in geological domains. Based on the advantage of LiDAR, the authors mainly deal with the applications of LiDAR data to such fields as surface land collapse, landslide and fault structure extraction. The review conclusion shows that airborne LiDAR technology is becoming an indispensable tool for above mentioned issues, especially in the local and large scale investigations of micro-topography. The technology not only can identify the surface collapse, landslide boundary and subtle faulted landform, but also be able to extract the filling parameters of collapsed surface, the geomorphic parameters of landslide stability evaluation and cracks. This technology has extensive prospect of applications in geological investigation.

Chemical Functionalization of Polysaccharides-Towards Biocompatible Hydrogels for Biomedical Applications.

PubMed

Kirschning, Andreas; Dibbert, Nick; Dräger, Gerald

2018-01-26

Hydrogels have emerged as a highly interdisciplinary topic as they play a significant role for a vast number of applications. They have been studied extensively as materials for contact lenses, wound dressing and as filler material in soft-tissue augmentation, in which classical polymer backbones such as hydroxyethylmethacrylate (HEMA) are typically employed. More recently, polysaccharides have received attention, particularly in the fields of regenerative medicine and tissue engineering, as ideal candidate materials for artificial extracellular matrices (ECM). The polysaccharides of choice are dextran, alginate, chitosan, hyaluronic acid and pullulan and in order to obtain suitable hydrogels from these polysaccharides, controlled chemical functionalization is of critical importance. This short review summarizes recent developments in the chemical derivatization of polysaccharides to pave the way for crosslinking and to decorate individual polysaccharide chains with bioactive ligands. The report covers convergent and divergent protocols for crosslinking, as well strategies for bisfunctionalization of polysaccharides. Additionally, information on biological properties and biomedical applications are covered. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coherent perfect absorbers: linear control of light with light

NASA Astrophysics Data System (ADS)

Baranov, Denis G.; Krasnok, Alex; Shegai, Timur; Alù, Andrea; Chong, Yidong

2017-12-01

The absorption of electromagnetic energy by a material is a phenomenon that underlies many applications, including molecular sensing, photocurrent generation and photodetection. Typically, the incident energy is delivered to the system through a single channel, for example, by a plane wave incident on one side of an absorber. However, absorption can be made much more efficient by exploiting wave interference. A coherent perfect absorber is a system in which the complete absorption of electromagnetic radiation is achieved by controlling the interference of multiple incident waves. Here, we review recent advances in the design and applications of such devices. We present the theoretical principles underlying the phenomenon of coherent perfect absorption and give an overview of the photonic structures in which it can be realized, including planar and guided-mode structures, graphene-based systems, parity-symmetric and time-symmetric structures, 3D structures and quantum-mechanical systems. We then discuss possible applications of coherent perfect absorption in nanophotonics, and, finally, we survey the perspectives for the future of this field.

Development and application of linear and nonlinear methods for interpretation of lightning strikes to in-flight aircraft

NASA Technical Reports Server (NTRS)

Rudolph, Terence; Perala, Rodney A.; Easterbrook, Calvin C.; Parker, Steven L.

1986-01-01

Since 1980, NASA has been collecting direct strike lightning data by flying an instrumented F-106B aircraft into thunderstorms. The continuing effort to interpret the measured data is reported here. Both linear and nonlinear finite difference modeling techniques are applied to the problem of lightning triggered by an aircraft in a thunderstorm. Five different aircraft are analyzed to determine the effect of aircraft size and shape on lightning triggering. The effect of lightning channel impedance on aircraft response is investigated. The particle environment in thunderstorms and electric field enhancements by typical ice particles is also investigated.

Rapid calibrated high-resolution hyperspectral imaging using tunable laser source

NASA Astrophysics Data System (ADS)

Nguyen, Lam K.; Margalith, Eli

2009-05-01

We present a novel hyperspectral imaging technique based on tunable laser technology. By replacing the broadband source and tunable filters of a typical NIR imaging instrument, several advantages are realized, including: high spectral resolution, highly variable field-of-views, fast scan-rates, high signal-to-noise ratio, and the ability to use optical fiber for efficient and flexible sample illumination. With this technique, high-resolution, calibrated hyperspectral images over the NIR range can be acquired in seconds. The performance of system features will be demonstrated on two example applications: detecting melamine contamination in wheat gluten and separating bovine protein from wheat protein in cattle feed.

A high-temperature superconducting Helmholtz probe for microscopy at 9.4 T.

PubMed

Hurlston, S E; Brey, W W; Suddarth, S A; Johnson, G A

1999-05-01

The design and operation of a high-temperature superconducting (HTS) probe for magnetic resonance microscopy (MRM) at 400 MHz are presented. The design of the probe includes a Helmholtz coil configuration and a stable open-cycle cooling mechanism. Characterization of coil operating parameters is presented to demonstrate the suitability of cryo-cooled coils for MRM. Specifically, the performance of the probe is evaluated by comparison of signal-to-noise (SNR) performance with that of a copper Helmholtz pair, analysis of B1 field homogeneity, and quantification of thermal stability. Images are presented to demonstrate the SNR advantage of the probe for typical MRM applications.

P2Y nucleotide receptors: promise of therapeutic applications.

PubMed

Jacobson, Kenneth A; Boeynaems, Jean-Marie

2010-07-01

Extracellular nucleotides, such as ATP and UTP, have distinct signaling roles through a class of G-protein-coupled receptors, termed P2Y. The receptor ligands are typically charged molecules of low bioavailability and stability in vivo. Recent progress in the development of selective agonists and antagonists for P2Y receptors and study of knockout mice have led to new drug concepts based on these receptors. The rapidly accelerating progress in this field has already resulted in drug candidates for cystic fibrosis, dry eye disease and thrombosis. On the horizon are novel treatments for cardiovascular diseases, inflammatory diseases and neurodegeneration. Published by Elsevier Ltd.

Streakline flow visualization of discrete-hole film cooling with normal, slanted, and compound angle injection

NASA Technical Reports Server (NTRS)

Colladay, R. S.; Russell, L. M.

1976-01-01

Film injection from discrete holes in a three-row, staggered array with five-diameter spacing was studied for three hole angles: (1) normal, (2) slanted 30 deg to the surface in the direction of the main stream, and (3) slanted 30 deg to the surface and 45 deg laterally to the main stream. The ratio of the boundary layer thickness-to-hole diameter and Reynolds number were typical of gas-turbine film-cooling applications. Detailed streaklines showing the turbulent motion of the injected air were obtained by photographing very small neutrally buoyant, helium-filled soap bubbles which follow the flow field.

Off-line data reduction

NASA Astrophysics Data System (ADS)

Gutowski, Marek W.

1992-12-01

Presented is a novel, heuristic algorithm, based on fuzzy set theory, allowing for significant off-line data reduction. Given the equidistant data, the algorithm discards some points while retaining others with their original values. The fraction of original data points retained is typically {1}/{6} of the initial value. The reduced data set preserves all the essential features of the input curve. It is possible to reconstruct the original information to high degree of precision by means of natural cubic splines, rational cubic splines or even linear interpolation. Main fields of application should be non-linear data fitting (substantial savings in CPU time) and graphics (storage space savings).

3D display for enhanced tele-operation and other applications

NASA Astrophysics Data System (ADS)

Edmondson, Richard; Pezzaniti, J. Larry; Vaden, Justin; Hyatt, Brian; Morris, James; Chenault, David; Bodenhamer, Andrew; Pettijohn, Bradley; Tchon, Joe; Barnidge, Tracy; Kaufman, Seth; Kingston, David; Newell, Scott

2010-04-01

In this paper, we report on the use of a 3D vision field upgrade kit for TALON robot consisting of a replacement flat panel stereoscopic display, and multiple stereo camera systems. An assessment of the system's use for robotic driving, manipulation, and surveillance operations was conducted. A replacement display, replacement mast camera with zoom, auto-focus, and variable convergence, and a replacement gripper camera with fixed focus and zoom comprise the upgrade kit. The stereo mast camera allows for improved driving and situational awareness as well as scene survey. The stereo gripper camera allows for improved manipulation in typical TALON missions.

Giant magnetic anisotropy of rare-earth adatoms and dimers adsorbed by graphene oxide.

PubMed

Zhang, Kai-Cheng; Li, Yong-Feng; Liu, Yong; Zhu, Yan; Shi, Li-Bin

2017-05-24

Nowadays, transition-metal adatoms and dimers with giant magnetic anisotropy have attracted much attention due to their potential applications in data storage, spintronics and quantum computations. Using density-functional calculations, we investigated the magnetic anisotropy of the rare-earth adatoms and dimers adsorbed by graphene oxide. Our calculations reveal that the adatoms of Tm, Er and Sm possess giant magnetic anisotropy, typically larger than 40 meV. When the dimers of (Tm,Er,Sm)-Ir are adsorbed onto graphene oxide, the magnetic anisotropy even exceeds 200 meV. The magnetic anisotropy can be tuned by the external electric field as well as the environment.

Increasing the information acquisition volume in iris recognition systems.

PubMed

Barwick, D Shane

2008-09-10

A significant hurdle for the widespread adoption of iris recognition in security applications is that the typically small imaging volume for eye placement results in systems that are not user friendly. Separable cubic phase plates at the lens pupil have been shown to ameliorate this disadvantage by increasing the depth of field. However, these phase masks have limitations on how efficiently they can capture the information-bearing spatial frequencies in iris images. The performance gains in information acquisition that can be achieved by more general, nonseparable phase masks is demonstrated. A detailed design method is presented, and simulations using representative designs allow for performance comparisons.

Application Site and Mosquito Age Influences Malathion- and Permethrin-Induced Mortality in Culex quinquefasciatus (Diptera: Culicidae).

PubMed

Aldridge, Robert L; Kaufman, Phillip E; Bloomquist, Jeffrey R; Gezan, Salvador A; Linthicum, Kenneth J

2017-11-07

Concentrations of malathion and permethrin typical in droplets generated from ultra-low-volume and low-volume applications used to control mosquito populations were evaluated for efficacy against multiple-aged Culex quinquefasciatus Say (Diptera: Culicidae), using a topical bioassay. Although insecticide droplets will impinge on many exoskeletal body regions and a range of ages of mosquitoes in a population, traditional mosquito topical bioassays focus pesticide application to the mesothoracic pleural or dorsal regions across an average mosquito age (e.g., 3-7 d). Our results document nonuniform insecticide sensitivity across body regions at ages not previously assessed in mosquitoes (teneral and 14-d old). We expect our findings to influence the topical bioassay process, illustrating the difference in mosquito body regions and ages that ultimately may explain insecticide effectiveness wherever droplets impinge upon the mosquito body during field control applications. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

A review on recent contribution of meshfree methods to structure and fracture mechanics applications.

PubMed

Daxini, S D; Prajapati, J M

2014-01-01

Meshfree methods are viewed as next generation computational techniques. With evident limitations of conventional grid based methods, like FEM, in dealing with problems of fracture mechanics, large deformation, and simulation of manufacturing processes, meshfree methods have gained much attention by researchers. A number of meshfree methods have been proposed till now for analyzing complex problems in various fields of engineering. Present work attempts to review recent developments and some earlier applications of well-known meshfree methods like EFG and MLPG to various types of structure mechanics and fracture mechanics applications like bending, buckling, free vibration analysis, sensitivity analysis and topology optimization, single and mixed mode crack problems, fatigue crack growth, and dynamic crack analysis and some typical applications like vibration of cracked structures, thermoelastic crack problems, and failure transition in impact problems. Due to complex nature of meshfree shape functions and evaluation of integrals in domain, meshless methods are computationally expensive as compared to conventional mesh based methods. Some improved versions of original meshfree methods and other techniques suggested by researchers to improve computational efficiency of meshfree methods are also reviewed here.

Visualisation of an nsPEF induced calcium wave using the genetically encoded calcium indicator GCaMP in U87 human glioblastoma cells.

PubMed

Carr, Lynn; Bardet, Sylvia M; Arnaud-Cormos, Delia; Leveque, Philippe; O'Connor, Rodney P

2018-02-01

Cytosolic, synthetic chemical calcium indicators are typically used to visualise the rapid increase in intracellular calcium ion concentration that follows nanosecond pulsed electric field (nsPEF) application. This study looks at the application of genetically encoded calcium indicators (GECIs) to investigate the spatiotemporal nature of nsPEF-induced calcium signals using fluorescent live cell imaging. Calcium responses to 44kV/cm, 10ns pulses were observed in U87-MG cells expressing either a plasma membrane targeted GECI (GCaMP5-G), or one cytosolically expressed (GCaMP6-S), and compared to the response of cells loaded with cytosolic or plasma membrane targeted chemical calcium indicators. Application of 100 pulses, to cells containing plasma membrane targeted indicators, revealed a wave of calcium across the cell initiating at the cathode side. A similar spatial wave was not observed with cytosolic indicators with mobile calcium buffering properties. The speed of the wave was related to pulse application frequency and it was not propagated by calcium induced calcium release. Copyright © 2017 Elsevier B.V. All rights reserved.

[Audiovisual telecommunication by multimedia technology in HNO medicine. ISDN--internet--ATM].

PubMed

Plinkert, P K; Plinkert, B; Kurek, R; Zenner, H P

2000-11-01

Telemedicine includes all medical activities in diagnosis, therapeutics, or social medicine undertaken by means of an electronic transfer medium, enabling the transmission of visual and acoustic information over long distances to doctors not personally present at the place of the requested consultation. Most experience with telemedicine applications has been gained in the field of diagnosis (teleconsultation, teleradiology, telepathology) and is expanding to quality control and quality assurance. Decisive for each form of application is its availability, practicability, cost, safety, and especially quality of audiovisual transmission. For telesurgical applications, particularly the use of minimally invasive techniques in otorhinolaryngology, head, and neck surgery, the high quality transmission of audiovisual data in real time is necessary. Rapid expansion and further developments in transmission technologies and networks in the last decade have created several technologies with increased quality and costs. In this paper, we tested different transmission media for audiovisual telecommunication--integrated services digital network (ISDN), Internet, and asynchronous transfer mode (ATM)--using real time video transmission of typical operations in otorhinolaryngology. Their applications, costs, and future perspectives are discussed.

Ultrafast Modulation and Switching of Quantum-Well Lasers using Terahertz Fields

NASA Technical Reports Server (NTRS)

Ning, Cun-Zheng; Hughes, S.; Citrin, D.; Saini, Subhash (Technical Monitor)

1998-01-01

Modulation and switching of semiconductor lasers are important for laser-based information technology. Typically the speed of modulation and switching is limited by interband processes such as stimulated and spontaneous recombinations which occur on a nanosecond time scale. This is why the diode laser modulation has been restricted to tens of GHz. Modulation at higher speed is highly desirable as the information technology enters into the so-called tera-era. In this paper, we study the possibility of utilizing THz-field-induced plasma heating to modulate quantum-well lasers. This is a timely study since, with the advancement of THz solid-state sources and free-electron lasers, THz physics and related technology is currently coming out of its infancy. The investigation of interplaying THz and optical fields is also of intruiging fundamental interest. First, we introduce theoretical plasma heating results for the quantum-well optical amplifier in the presense of an intense half-cycle THz pulse. The heated carrier distributions are then utilized to calculate the THz-pulse-induced change in refractive index and gain profile. Since the electron-hole-plasma is heated using intraband transitions, we circumvent the usual complications due to an overall change in density, and the nonlinear recovery is governed solely by the carrier-LO-phonon interactions, typically 5 ps for a complete recovery. This procedure implies THz and sub-THz switching and recovery rates, respectively; using either gain modulation or index modulation. Plasma heating via steady-state THz fields is also studied. Finally, numerical simulation of a coupled set of equations to investigate the THz modulation based on a simplified model for quantum-well lasers is presented. Our results show that a semiconductor laser can be modulated at up to 1 THz with little distortion with a THz field amplitude at the order of a few kV/cm. Laser responses to a change in THz frequency will be shown. Constraints, practicalities, and applications will be discussed.

Controlling thermal properties of dense gas fluidized beds for concentrated solar power by internal and external solids circulation

NASA Astrophysics Data System (ADS)

Ammendola, Paola; Bareschino, Piero; Chirone, Riccardo; Salatino, Piero; Solimene, Roberto

2017-06-01

Fluidization technology displays a long record of success stories, mostly related to applications to thermal and thermochemical processes, which are fostering extension to novel and relatively unexplored fields. Application of fluidized beds to collection and thermal storage of solar radiation in Concentrated Solar Power (CSP) is one of the most promising, a field which poses challenging issues and great opportunities to fluidization scientists and technologists. The potential of this growing field calls for reconsideration of some of the typical design and operation guidelines and criteria, with the goal of exploiting the inherently good thermal performances of gas-fluidized beds at their best. "Creative" and non-conventional design and operation of fluidized beds, like those based on internal and external solids circulation, may be beneficial to the enhancement of thermal diffusivity and surface-to-bed heat transfer, improving the potential for application in the very demanding context of CSP with thermal energy storage. This paper investigated: i) a fluidized bed configuration with an uneven distribution of the fluidizing gas to promote vortices in the scale of bed height (internal solids circulation); ii) a dual fluidized bed configuration characterized by an external solids circulation achieved by the operation of a riser and a bubbling fluidized bed. CFD simulations showed the hydrodynamics conditions under which the internal solids circulation was established. The hydrodynamic characterization of the external solids circulation was achieved by an experimental study carried out with different cold models. The dual fluidized bed system was optimized in terms of operating conditions and geometrical features of the connections between two fluidized beds.

Pacific Symposium on Biocomputing 2002/2003/2004

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

A.Keith Dunker

2004-10-26

Brief introduction to Pacific Symposium on Biocomputing The Pacific Symposium on Biocomputing is an international, multidisciplinary conference covering current research in the theory and the application of computational methods in problems of biological significance. Researchers from the United States, the Asian Pacific nations and around the world gather each year at PSB to exchange research results and discuss open issues in all aspects of computational biology. PSB provides a forum for work on databases, algorithms, interfaces, visualization, modeling and other computational methods, as applied to biological problems. The data-rich areas of molecular biology are emphasized. PSB is the only meetingmore » in the bioinformatics field with sessions defined dynamically each year in response to specific proposals from the participants. Sessions are organized by leaders in emerging areas to provide forums for publication and for discussion of research in biocomputing ''hot topics''. PSB therefore enables discussion of emerging methods and approaches in this rapidly changing field. PSB has been designated as one of the major meetings in this field by the recently established International Society for Computational Biology (see www.iscb.org). Papers and presentations are peer reviewed typically with 3 reviews per paper plus editorial oversight from the conference organizers. The accepted papers are published in an archival proceedings volume, which is indexed by PubMed, and electronically (see http://psb.stanford.edu/). Finally, given the tight schedule from submission of papers to their publication, typically 5 to 5 1/2 months, the PSB proceedings each year represents one of the most up-to-date surveys of current trends in bioinformatics.« less

Flow-induced vibration and fretting-wear damage in a moisture separator reheater

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

Pettigrew, M.J.; Taylor, C.E.; Fisher, N.J.

1996-12-01

Tube failures due to excessive flow-induced vibration were experienced in the tube bundles of moisture separator reheaters in a BWR nuclear station. This paper presents the results of a root cause analysis and covers recommendations for continued operation and for replacement tube bundles. The following tasks are discussed: tube failure analysis; flow velocity distribution calculations; flow-induced vibration analysis with particular emphasis on finned-tubes; fretting-wear testing of a tube and tube-support material combination under simulated operating conditions; field measurements of flow-induced vibration; and development of vibration specifications for replacement tube bundles. The effect of transient operating conditions and of other operationalmore » changes such as tube fouling were considered in the analysis. This paper outlines a typical field problem and illustrates the application of flow-induced vibration technology for the solution of a practical problem.« less

Review of the Functions of Archimedes’ Spiral Metallic Nanostructures

PubMed Central

Li, Zixiang; Zhang, Jingran; Guo, Kai; Shen, Fei; Zhou, Qingfeng; Zhou, Hongping

2017-01-01

Here, we have reviewed some typical plasmonic structures based on Archimedes’ spiral (AS) architectures, which can produce polarization-sensitive focusing phenomenon and generate plasmonic vortices (PVs) carrying controllable orbital angular momentum (OAM) because of the relation between the incident polarized states and the chiralities of the spiral structures. These features can be used to analyze different circular polarization states, which has been one of the rapidly developing researching topics in nanophotonics in recent years. Many investigations demonstrate that the multifunctional spiral-based plasmonic structures are excellent choices for chiral selection and generating the transmitted field with well-defined OAM. The circular polarization extinction ratio, as an evaluation criterion for the polarization selectivity of a designed structure, could be effectively improved by properly modulating the parameters of spiral structures. Such functional spiral plasmonic nanostructures are promising for applications in analyzing circular polarization light, full Stokes vector polarimetric sensors, near-field imaging, and so on. PMID:29165382

Poor Man's Virtual Camera: Real-Time Simultaneous Matting and Camera Pose Estimation.

PubMed

Szentandrasi, Istvan; Dubska, Marketa; Zacharias, Michal; Herout, Adam

2016-03-18

Today's film and advertisement production heavily uses computer graphics combined with living actors by chromakeying. The matchmoving process typically takes a considerable manual effort. Semi-automatic matchmoving tools exist as well, but they still work offline and require manual check-up and correction. In this article, we propose an instant matchmoving solution for green screen. It uses a recent technique of planar uniform marker fields. Our technique can be used in indie and professional filmmaking as a cheap and ultramobile virtual camera, and for shot prototyping and storyboard creation. The matchmoving technique based on marker fields of shades of green is very computationally efficient: we developed and present in the article a mobile application running at 33 FPS. Our technique is thus available to anyone with a smartphone at low cost and with easy setup, opening space for new levels of filmmakers' creative expression.

The Clinical Assessment in the Legal Field: An Empirical Study of Bias and Limitations in Forensic Expertise

PubMed Central

Iudici, Antonio; Salvini, Alessandro; Faccio, Elena; Castelnuovo, Gianluca

2015-01-01

According to the literature, psychological assessment in forensic contexts is one of the most controversial application areas for clinical psychology. This paper presents a review of systematic judgment errors in the forensic field. Forty-six psychological reports written by psychologists, court consultants, have been analyzed with content analysis to identify typical judgment errors related to the following areas: (a) distortions in the attribution of causality, (b) inferential errors, and (c) epistemological inconsistencies. Results indicated that systematic errors of judgment, usually referred also as “the man in the street,” are widely present in the forensic evaluations of specialist consultants. Clinical and practical implications are taken into account. This article could lead to significant benefits for clinical psychologists who want to deal with this sensitive issue and are interested in improving the quality of their contribution to the justice system. PMID:26648892

Application of text mining in the biomedical domain.

PubMed

Fleuren, Wilco W M; Alkema, Wynand

2015-03-01

In recent years the amount of experimental data that is produced in biomedical research and the number of papers that are being published in this field have grown rapidly. In order to keep up to date with developments in their field of interest and to interpret the outcome of experiments in light of all available literature, researchers turn more and more to the use of automated literature mining. As a consequence, text mining tools have evolved considerably in number and quality and nowadays can be used to address a variety of research questions ranging from de novo drug target discovery to enhanced biological interpretation of the results from high throughput experiments. In this paper we introduce the most important techniques that are used for a text mining and give an overview of the text mining tools that are currently being used and the type of problems they are typically applied for. Copyright © 2015 Elsevier Inc. All rights reserved.

Methods, Tools and Current Perspectives in Proteogenomics *

PubMed Central

Ruggles, Kelly V.; Krug, Karsten; Wang, Xiaojing; Clauser, Karl R.; Wang, Jing; Payne, Samuel H.; Fenyö, David; Zhang, Bing; Mani, D. R.

2017-01-01

With combined technological advancements in high-throughput next-generation sequencing and deep mass spectrometry-based proteomics, proteogenomics, i.e. the integrative analysis of proteomic and genomic data, has emerged as a new research field. Early efforts in the field were focused on improving protein identification using sample-specific genomic and transcriptomic sequencing data. More recently, integrative analysis of quantitative measurements from genomic and proteomic studies have identified novel insights into gene expression regulation, cell signaling, and disease. Many methods and tools have been developed or adapted to enable an array of integrative proteogenomic approaches and in this article, we systematically classify published methods and tools into four major categories, (1) Sequence-centric proteogenomics; (2) Analysis of proteogenomic relationships; (3) Integrative modeling of proteogenomic data; and (4) Data sharing and visualization. We provide a comprehensive review of methods and available tools in each category and highlight their typical applications. PMID:28456751

Anomalous electronic structure and magnetoresistance in TaAs 2

DOE PAGES

Luo, Yongkang; McDonald, R. D.; Rosa, P. F. S.; ...

2016-01-01

We report that the change in resistance of a material in a magnetic field reflects its electronic state. In metals with weakly- or non-interacting electrons, the resistance typically increases upon the application of a magnetic field. In contrast, negative magnetoresistance may appear under some circumstances, e.g., in metals with anisotropic Fermi surfaces or with spin-disorder scattering and semimetals with Dirac or Weyl electronic structures. Here we show that the non-magnetic semimetal TaAs 2 possesses a very large negative magnetoresistance, with an unknown scattering mechanism. In conclusion, density functional calculations find that TaAs 2 is a new topological semimetal [Z 2more » invariant (0;111)] without Dirac dispersion, demonstrating that a negative magnetoresistance in non-magnetic semimetals cannot be attributed uniquely to the Adler-Bell-Jackiw chiral anomaly of bulk Dirac/Weyl fermions.« less

Display challenges resulting from the use of wide field of view imaging devices

NASA Astrophysics Data System (ADS)

Petty, Gregory J.; Fulton, Jack; Nicholson, Gail; Seals, Ean

2012-06-01

As focal plane array technologies advance and imagers increase in resolution, display technology must outpace the imaging improvements in order to adequately represent the complete data collection. Typical display devices tend to have an aspect ratio similar to 4:3 or 16:9, however a breed of Wide Field of View (WFOV) imaging devices exist that skew from the norm with aspect ratios as high as 5:1. This particular quality, when coupled with a high spatial resolution, presents a unique challenge for display devices. Standard display devices must choose between resizing the image data to fit the display and displaying the image data in native resolution and truncating potentially important information. The problem compounds when considering the applications; WFOV high-situationalawareness imagers are sought for space-limited military vehicles. Tradeoffs between these issues are assessed to the image quality of the WFOV sensor.

Magnetization and magnetoresistance of common alloy wires used in cryogenic instrumentation.

PubMed

Abrecht, M; Adare, A; Ekin, J W

2007-04-01

We present magnetization and magnetoresistance data at liquid-helium and liquid-nitrogen temperatures for wire materials commonly used for instrumentation wiring of specimens, sensors, and heaters in cryogenic probes. The magnetic susceptibilities in Systeme International units at 4.2 K were found to be: Manganin 1.25x10(-2), Nichrome 5.6x10(-3), and phosphor bronze -3.3x10(-5), indicating that phosphor bronze is the most suitable for high-field applications. We also show the ferromagnetic hysteresis loop of Constantan wire at liquid-helium temperature. The magnetoresistance of these four wires was relatively small: the changes in resistance at 4 K due to a 10 T transverse magnetic field are -2.56% for Constantan, -2.83% for Manganin, +0.69% for Nichrome, and +4.5% for phosphor bronze, compared to about +188% for a typical copper wire under the same conditions.

Elemental, morphological, structural, optical, and magnetic properties of erbium doped ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Poornaprakash, B.; Chalapathi, U.; Purusottam Reddy, B.; Prabhakar Vattikuti, S. V.; Siva Pratap Reddy, M.; Park, Si-Hyun

2018-03-01

The sensible tuning of the structural, optical, and magnetic properties of ZnO nanoparticles (NPs) with suitable doping can enhance their applicability in diverse fields. In this study, we synthesized ZnO NPs with Er (0-4 at%) doping and their elemental, structural, optical, and magnetic properties were studied. Both field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) studies of the suspensions consist of hexagonal shaped NPs. All the prepared NPs exhibited hexagonal phase as demonstrated by powder x-ray diffraction studies. A blue shift was observed in the Er doped ZnO NPs compared to pure ZnO, indicating the increased optical bandgap. Vibrating sample magnetometer studies exhibited the pure ZnO NPs was typical diamagnetic feature whereas all the Er doped ZnO NPs were paramagnetic feature at 300 K. This is the first paramagnetic report on Er doped ZnO NPs.

SlideJ: An ImageJ plugin for automated processing of whole slide images.

PubMed

Della Mea, Vincenzo; Baroni, Giulia L; Pilutti, David; Di Loreto, Carla

2017-01-01

The digital slide, or Whole Slide Image, is a digital image, acquired with specific scanners, that represents a complete tissue sample or cytological specimen at microscopic level. While Whole Slide image analysis is recognized among the most interesting opportunities, the typical size of such images-up to Gpixels- can be very demanding in terms of memory requirements. Thus, while algorithms and tools for processing and analysis of single microscopic field images are available, Whole Slide images size makes the direct use of such tools prohibitive or impossible. In this work a plugin for ImageJ, named SlideJ, is proposed with the objective to seamlessly extend the application of image analysis algorithms implemented in ImageJ for single microscopic field images to a whole digital slide analysis. The plugin has been complemented by examples of macro in the ImageJ scripting language to demonstrate its use in concrete situations.

Magnetization and magnetoresistance of common alloy wires used in cryogenic instrumentation

NASA Astrophysics Data System (ADS)

Abrecht, M.; Adare, A.; Ekin, J. W.

2007-04-01

We present magnetization and magnetoresistance data at liquid-helium and liquid-nitrogen temperatures for wire materials commonly used for instrumentation wiring of specimens, sensors, and heaters in cryogenic probes. The magnetic susceptibilities in Systeme International units at 4.2 K were found to be: Manganin 1.25×10-2, Nichrome 5.6×10-3, and phosphor bronze -3.3×10-5, indicating that phosphor bronze is the most suitable for high-field applications. We also show the ferromagnetic hysteresis loop of Constantan wire at liquid-helium temperature. The magnetoresistance of these four wires was relatively small: the changes in resistance at 4 K due to a 10 T transverse magnetic field are -2.56% for Constantan, -2.83% for Manganin, +0.69% for Nichrome, and +4.5% for phosphor bronze, compared to about +188% for a typical copper wire under the same conditions.

SlideJ: An ImageJ plugin for automated processing of whole slide images

PubMed Central

Baroni, Giulia L.; Pilutti, David; Di Loreto, Carla

2017-01-01

The digital slide, or Whole Slide Image, is a digital image, acquired with specific scanners, that represents a complete tissue sample or cytological specimen at microscopic level. While Whole Slide image analysis is recognized among the most interesting opportunities, the typical size of such images—up to Gpixels- can be very demanding in terms of memory requirements. Thus, while algorithms and tools for processing and analysis of single microscopic field images are available, Whole Slide images size makes the direct use of such tools prohibitive or impossible. In this work a plugin for ImageJ, named SlideJ, is proposed with the objective to seamlessly extend the application of image analysis algorithms implemented in ImageJ for single microscopic field images to a whole digital slide analysis. The plugin has been complemented by examples of macro in the ImageJ scripting language to demonstrate its use in concrete situations. PMID:28683129

Electronic spin transport in gate-tunable black phosphorus spin valves

NASA Astrophysics Data System (ADS)

Liu, Jiawei; Avsar, Ahmet; Tan, Jun You; Oezyilmaz, Barbaros

High charge mobility, the electric field effect and small spin-orbit coupling make semiconducting black phosphorus (BP) a promising material for spintronics device applications requiring long spin distance spin communication with all rectification and amplification actions. Towards this, we study the all electrical spin injection, transport and detection under non-local spin valve geometry in fully encapsulated ultra-thin BP devices. We observe spin relaxation times as high as 4 ns, with spin relaxation lengths exceeding 6 μm. These values are an order of magnitude higher than what have been measured in typical graphene spin valve devices. Moreover, the spin transport depends strongly on charge carrier concentration and can be manipulated in a spin transistor-like manner by controlling electric field. This behaviour persists even at room temperature. Finally, we will show that similar to its electrical and optical properties, spin transport property is also strongly anisotropic.

Graphene Monoxide Bilayer As a High-Performance on/off Switching Media for Nanoelectronics.

PubMed

Woo, Jungwook; Yun, Kyung-Han; Chung, Yong-Chae

2016-04-27

The geometries and electronic characteristics of the graphene monoxide (GMO) bilayer are predicted via density functional theory (DFT) calculations. All the possible sequences of the GMO bilayer show the typical interlayer bonding characteristics of two-dimensional bilayer systems with a weak van der Waals interaction. The band gap energies of the GMO bilayers are predicted to be adequate for electronic device application, indicating slightly smaller energy gaps (0.418-0.448 eV) compared to the energy gap of the monolayer (0.536 eV). Above all, in light of the band gap engineering, the band gap of the GMO bilayer responds to the external electric field sensitively. As a result, a semiconductor-metal transition occurs at a small critical electric field (EC = 0.22-0.30 V/Å). It is therefore confirmed that the GMO bilayer is a strong candidate for nanoelectronics.

Tunable quasiparticle trapping in Meissner and vortex states of mesoscopic superconductors.

PubMed

Taupin, M; Khaymovich, I M; Meschke, M; Mel'nikov, A S; Pekola, J P

2016-03-16

Nowadays, superconductors serve in numerous applications, from high-field magnets to ultrasensitive detectors of radiation. Mesoscopic superconducting devices, referring to those with nanoscale dimensions, are in a special position as they are easily driven out of equilibrium under typical operating conditions. The out-of-equilibrium superconductors are characterized by non-equilibrium quasiparticles. These extra excitations can compromise the performance of mesoscopic devices by introducing, for example, leakage currents or decreased coherence time in quantum devices. By applying an external magnetic field, one can conveniently suppress or redistribute the population of excess quasiparticles. In this article, we present an experimental demonstration and a theoretical analysis of such effective control of quasiparticles, resulting in electron cooling both in the Meissner and vortex states of a mesoscopic superconductor. We introduce a theoretical model of quasiparticle dynamics, which is in quantitative agreement with the experimental data.

Tunable quasiparticle trapping in Meissner and vortex states of mesoscopic superconductors

PubMed Central

Taupin, M.; Khaymovich, I. M.; Meschke, M.; Mel'nikov, A. S.; Pekola, J. P.

2016-01-01

Nowadays, superconductors serve in numerous applications, from high-field magnets to ultrasensitive detectors of radiation. Mesoscopic superconducting devices, referring to those with nanoscale dimensions, are in a special position as they are easily driven out of equilibrium under typical operating conditions. The out-of-equilibrium superconductors are characterized by non-equilibrium quasiparticles. These extra excitations can compromise the performance of mesoscopic devices by introducing, for example, leakage currents or decreased coherence time in quantum devices. By applying an external magnetic field, one can conveniently suppress or redistribute the population of excess quasiparticles. In this article, we present an experimental demonstration and a theoretical analysis of such effective control of quasiparticles, resulting in electron cooling both in the Meissner and vortex states of a mesoscopic superconductor. We introduce a theoretical model of quasiparticle dynamics, which is in quantitative agreement with the experimental data. PMID:26980225

Model-based machine learning.

PubMed

Bishop, Christopher M

2013-02-13

Several decades of research in the field of machine learning have resulted in a multitude of different algorithms for solving a broad range of problems. To tackle a new application, a researcher typically tries to map their problem onto one of these existing methods, often influenced by their familiarity with specific algorithms and by the availability of corresponding software implementations. In this study, we describe an alternative methodology for applying machine learning, in which a bespoke solution is formulated for each new application. The solution is expressed through a compact modelling language, and the corresponding custom machine learning code is then generated automatically. This model-based approach offers several major advantages, including the opportunity to create highly tailored models for specific scenarios, as well as rapid prototyping and comparison of a range of alternative models. Furthermore, newcomers to the field of machine learning do not have to learn about the huge range of traditional methods, but instead can focus their attention on understanding a single modelling environment. In this study, we show how probabilistic graphical models, coupled with efficient inference algorithms, provide a very flexible foundation for model-based machine learning, and we outline a large-scale commercial application of this framework involving tens of millions of users. We also describe the concept of probabilistic programming as a powerful software environment for model-based machine learning, and we discuss a specific probabilistic programming language called Infer.NET, which has been widely used in practical applications.

Model-based machine learning

PubMed Central

Bishop, Christopher M.

2013-01-01

Several decades of research in the field of machine learning have resulted in a multitude of different algorithms for solving a broad range of problems. To tackle a new application, a researcher typically tries to map their problem onto one of these existing methods, often influenced by their familiarity with specific algorithms and by the availability of corresponding software implementations. In this study, we describe an alternative methodology for applying machine learning, in which a bespoke solution is formulated for each new application. The solution is expressed through a compact modelling language, and the corresponding custom machine learning code is then generated automatically. This model-based approach offers several major advantages, including the opportunity to create highly tailored models for specific scenarios, as well as rapid prototyping and comparison of a range of alternative models. Furthermore, newcomers to the field of machine learning do not have to learn about the huge range of traditional methods, but instead can focus their attention on understanding a single modelling environment. In this study, we show how probabilistic graphical models, coupled with efficient inference algorithms, provide a very flexible foundation for model-based machine learning, and we outline a large-scale commercial application of this framework involving tens of millions of users. We also describe the concept of probabilistic programming as a powerful software environment for model-based machine learning, and we discuss a specific probabilistic programming language called Infer.NET, which has been widely used in practical applications. PMID:23277612

A scale out approach towards neural induction of human induced pluripotent stem cells for neurodevelopmental toxicity studies.

PubMed

Miranda, Cláudia C; Fernandes, Tiago G; Pinto, Sandra N; Prieto, Manuel; Diogo, M Margarida; Cabral, Joaquim M S

2018-05-21

Stem cell's unique properties confer them a multitude of potential applications in the fields of cellular therapy, disease modelling and drug screening fields. In particular, the ability to differentiate neural progenitors (NP) from human induced pluripotent stem cells (hiPSCs) using chemically-defined conditions provides an opportunity to create a simple and straightforward culture platform for application in these fields. Here, we demonstrated that hiPSCs are capable of undergoing neural commitment inside microwells, forming characteristic neural structures resembling neural rosettes and further give rise to glial and neuronal cells. Furthermore, this platform can be applied towards the study of the effect of neurotoxic molecules that impair normal embryonic development. As a proof of concept, the neural teratogenic potential of the antiepileptic drug valproic acid (VPA) was analyzed. It was verified that exposure to VPA, close to typical dosage values (0.3 to 0.75 mM), led to a prevalence of NP structures over neuronal differentiation, as confirmed by analysis of the expression of neural cell adhesion molecule, as well as neural rosette number and morphology assessment. The methodology proposed herein for the generation and neural differentiation of hiPSC aggregates can potentially complement current toxicity tests such as the humanized embryonic stem cell test for the detection of teratogenic compounds that can interfere with normal embryonic development. Copyright © 2018 Elsevier B.V. All rights reserved.

Promise and progress in environmental genomics: a status report on the applications of gene expression-based microarray studies in ecologically relevant fish species.

PubMed

Hook, S E

2010-12-01

The advent of any new technology is typically met with great excitement. So it was a few years ago, when the combination of advances in sequencing technology and the development of microarray technology made measurements of global gene expression in ecologically relevant species possible. Many of the review papers published around that time promised that these new technologies would revolutionize environmental biology as they had revolutionized medicine and related fields. A few years have passed since these technological advancements have been made, and the use of microarray studies in non-model fish species has been adopted in many laboratories internationally. Has the relatively widespread adoption of this technology really revolutionized the fields of environmental biology, including ecotoxicology, aquaculture and ecology, as promised? Or have these studies merely become a novelty and a potential distraction for scientists addressing environmentally relevant questions? In this review, the promises made in early review papers, in particular about the advances that the use of microarrays would enable, are summarized; these claims are compared to the results of recent studies to determine whether the forecasted changes have materialized. Some applications, as discussed in the paper, have been realized and have led to advances in their field, others are still under development. © 2010 CSIRO. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.

Photo-conductive detection of continuous THz waves via manipulated ultrafast process in nanostructures

NASA Astrophysics Data System (ADS)

Moon, Kiwon; Lee, Eui Su; Lee, Il-Min; Park, Dong Woo; Park, Kyung Hyun

2018-01-01

Time-domain and frequency-domain terahertz (THz) spectroscopy systems often use materials fabricated with exotic and expensive methods that intentionally introduce defects to meet short carrier lifetime requirements. In this study, we demonstrate the development of a nano-photomixer that meets response speed requirements without using defect-incorporated, low-temperature-grown (LTG) semiconductors. Instead, we utilized a thin InGaAs layer grown on a semi-insulating InP substrate by metal-organic chemical vapor deposition (MOCVD) combined with nano-electrodes to manipulate local ultrafast photo-carrier dynamics via a carefully designed field-enhancement and plasmon effect. The developed nano-structured photomixer can detect continuous-wave THz radiation up to a frequency of 2 THz with a peak carrier collection efficiency of 5%, which is approximately 10 times better than the reference efficiency of 0.4%. The better efficiency results from the high carrier mobility of the MOCVD-grown InGaAs thin layer with the coincidence of near-field and plasmon-field distributions in the nano-structure. Our result not only provides a generally applicable methodology for manipulating ultrafast carrier dynamics by means of nano-photonic techniques to break the trade-off relation between the carrier lifetime and mobility in typical LTG semiconductors but also contributes to mass-producible photo-conductive THz detectors to facilitate the widespread application of THz technology.

Hydrogen molecules and chains in a superstrong magnetic field

NASA Technical Reports Server (NTRS)

Lai, Dong; Salpeter, Edwin E.; Shapiro, Stuart L.

1992-01-01

The electronic structures of hydrogen polymolecules H(n) (n = 2,3,4,...) is studied in a superstrong magnetic field (B greater than about 10 exp 12 G) typically found on the surface of a neutron star. Simple analytical scaling relations for several limiting cases (e.g., large n, high B field) are derived. The binding energies of H(n) molecules are numerically calculated for various magnetic-field strengths. For a given magnetic-field strength, the binding energy per atom in the H(n) molecules is found to approach a constant value as n increases. For typical field strengths of interest, energy saturation is essentially achieved once n exceeds 3 to 4. Also considered is the structure of negative H ions in a high magnetic field. For B about 10 exp 12 G, the dissociation energy of an atom in a hydrogen chain and the ionization potential of H(-) are smaller than the ionization potential of neutral atomic hydrogen.

Synthesis of In2O3 nanowire-decorated Ga2O3 nanobelt heterostructures and their electrical and field-emission properties.

PubMed

Lin, Jing; Huang, Yang; Bando, Yoshio; Tang, Chengchun; Li, Chun; Golberg, Dmitri

2010-04-27

We report on the synthesis of In2O3 nanowire-decorated Ga2O3 nanobelt heterostructures via a simple catalyst-free method. A typical heterostructure, where an In2O3 nanowire forms a sort of a "dorsal fin" on the Ga2O3 nanobelt, exhibits the T-shaped cross-section. The structure, electrical porperties, and field-emission properties of this material are systematically investigated. The heterostructures possess a typical n-type semiconducting behavior with enhanced conductivity. Field-emission measurements show that they have a low turn-on field (approximately 1.31 V/microm) and a high field-enhancement factor (over 4000). The excellent field-emission characteristics are attributed to their special geometry and good electrical properties. The present In2O3-decorated Ga2O3 heterostructures are envisaged to be decent field-emitters useful in advanced electronic and optoelectronic nanodevices.

Diode laser absorption sensors for gas-dynamic and combustion flows

NASA Technical Reports Server (NTRS)

Allen, M. G.

1998-01-01

Recent advances in room-temperature, near-IR and visible diode laser sources for tele-communication, high-speed computer networks, and optical data storage applications are enabling a new generation of gas-dynamic and combustion-flow sensors based on laser absorption spectroscopy. In addition to conventional species concentration and density measurements, spectroscopic techniques for temperature, velocity, pressure and mass flux have been demonstrated in laboratory, industrial and technical flows. Combined with fibreoptic distribution networks and ultrasensitive detection strategies, compact and portable sensors are now appearing for a variety of applications. In many cases, the superior spectroscopic quality of the new laser sources compared with earlier cryogenic, mid-IR devices is allowing increased sensitivity of trace species measurements, high-precision spectroscopy of major gas constituents, and stable, autonomous measurement systems. The purpose of this article is to review recent progress in this field and suggest likely directions for future research and development. The various laser-source technologies are briefly reviewed as they relate to sensor applications. Basic theory for laser absorption measurements of gas-dynamic properties is reviewed and special detection strategies for the weak near-IR and visible absorption spectra are described. Typical sensor configurations are described and compared for various application scenarios, ranging from laboratory research to automated field and airborne packages. Recent applications of gas-dynamic sensors for air flows and fluxes of trace atmospheric species are presented. Applications of gas-dynamic and combustion sensors to research and development of high-speed flows aeropropulsion engines, and combustion emissions monitoring are presented in detail, along with emerging flow control systems based on these new sensors. Finally, technology in nonlinear frequency conversion, UV laser materials, room-temperature mid-IR materials and broadly tunable multisection devices is reviewed to suggest new sensor possibilities.

Strain driven anisotropic magnetoresistance in antiferromagnetic La0.4Sr0.6MnO3 thin films

NASA Astrophysics Data System (ADS)

Ward, T. Zac; Wong, A. T.; Takamura, Yayoi; Herklotz, Andreas

2015-03-01

Antiferromagnets (AFM) are a promising alternative to ferromagnets (FM) in spintronic applications. The reason stems from the fact that at high data storage densities stray fields could destroy FM set states while AFMs would be relatively insensitive to this data corruption. This work presents the first ever example of antiferromagnetic La0.4Sr0.6MnO3 thin films stabilized in different strain states. Strain is found to drive different types of AFM ordering, and these variations in ordering type are shown to have a profound impact on both the magnitude and character of the materials' resistive response to magnetic field direction, or anisotropic magnetoresistance (AMR) behavior (one standard of spintronic suitability). The compressively strained film shows the highest recorded AMR response in an ohmic AFM device of 63%, while the tensile strained film shows a typical AFM AMR of 0.6%. These findings demonstrate the necessity of understanding electron ordering in AFM spintronic applications and provide a new benchmark for AMR response. This work was supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division.

Dynamic modelling and simulation of CSP plant based on supercritical carbon dioxide closed Brayton cycle

NASA Astrophysics Data System (ADS)

Hakkarainen, Elina; Sihvonen, Teemu; Lappalainen, Jari

2017-06-01

Supercritical carbon dioxide (sCO2) has recently gained a lot of interest as a working fluid in different power generation applications. For concentrated solar power (CSP) applications, sCO2 provides especially interesting option if it could be used both as the heat transfer fluid (HTF) in the solar field and as the working fluid in the power conversion unit. This work presents development of a dynamic model of CSP plant concept, in which sCO2 is used for extracting the solar heat in Linear Fresnel collector field, and directly applied as the working fluid in the recuperative Brayton cycle; these both in a single flow loop. We consider the dynamic model is capable to predict the system behavior in typical operational transients in a physically plausible way. The novel concept was tested through simulation cases under different weather conditions. The results suggest that the concept can be successfully controlled and operated in the supercritical region to generate electric power during the daytime, and perform start-up and shut down procedures in order to stay overnight in sub-critical conditions. Besides the normal daily operation, the control system was demonstrated to manage disturbances due to sudden irradiance changes.

Use of a night vision intensifier for direct visualization by eye of far-red and near-infrared fluorescence through an optical microscope.

PubMed

Siddiqi, M A; Kilduff, G M; Gearhart, J D

2003-11-01

We describe the design, construction and testing of a prototype device that allows the direct visualization by eye of far-red and near-infrared (NIR) fluorescence through an optical microscope. The device incorporates a gallium arsenide (GaAs) image intensifier, typically utilized in low-light or 'night vision' applications. The intensifier converts far-red and NIR light into electrons and then into green light, which is visible to the human eye. The prototype makes possible the direct, real-time viewing by eye of normally invisible far-red and NIR fluorescence from a wide variety of fluorophores, using the full field of view of the microscope to which it is applied. The high sensitivity of the image intensifier facilitates the viewing of a wide variety of photosensitive specimens, including live cells and embryos, at vastly reduced illumination levels in both fluorescence and bright-field microscopy. Modifications to the microscope are not required in order to use the prototype, which is fully compatible with all current fluorescence techniques. Refined versions of the prototype device will have broad research and clinical applications.

Improving Rice Modeling Success Rate with Ternary Non-structural Fertilizer Response Model.

PubMed

Li, Juan; Zhang, Mingqing; Chen, Fang; Yao, Baoquan

2018-06-13

Fertilizer response modelling is an important technical approach to realize metrological fertilization on rice. With the goal of solving the problems of a low success rate of a ternary quadratic polynomial model (TPFM) and to expand the model's applicability, this paper established a ternary non-structural fertilizer response model (TNFM) based on the experimental results from N, P and K fertilized rice fields. Our research results showed that the TNFM significantly improved the modelling success rate by addressing problems arising from setting the bias and multicollinearity in a TPFM. The results from 88 rice field trials in China indicated that the proportion of typical TNFMs that satisfy the general fertilizer response law of plant nutrition was 40.9%, while the analogous proportion of TPFMs was only 26.1%. The recommended fertilization showed a significant positive linear correlation between the two models, and the parameters N 0 , P 0 and K 0 that estimated the value of soil supplying nutrient equivalents can be used as better indicators of yield potential in plots where no N or P or K fertilizer was applied. The theoretical analysis showed that the new model has a higher fitting accuracy and a wider application range.

Kalman filter-based tracking of moving objects using linear ultrasonic sensor array for road vehicles

NASA Astrophysics Data System (ADS)

Li, Shengbo Eben; Li, Guofa; Yu, Jiaying; Liu, Chang; Cheng, Bo; Wang, Jianqiang; Li, Keqiang

2018-01-01

Detection and tracking of objects in the side-near-field has attracted much attention for the development of advanced driver assistance systems. This paper presents a cost-effective approach to track moving objects around vehicles using linearly arrayed ultrasonic sensors. To understand the detection characteristics of a single sensor, an empirical detection model was developed considering the shapes and surface materials of various detected objects. Eight sensors were arrayed linearly to expand the detection range for further application in traffic environment recognition. Two types of tracking algorithms, including an Extended Kalman filter (EKF) and an Unscented Kalman filter (UKF), for the sensor array were designed for dynamic object tracking. The ultrasonic sensor array was designed to have two types of fire sequences: mutual firing or serial firing. The effectiveness of the designed algorithms were verified in two typical driving scenarios: passing intersections with traffic sign poles or street lights, and overtaking another vehicle. Experimental results showed that both EKF and UKF had more precise tracking position and smaller RMSE (root mean square error) than a traditional triangular positioning method. The effectiveness also encourages the application of cost-effective ultrasonic sensors in the near-field environment perception in autonomous driving systems.

Dynamics of Cd, Cu and Pb added to soil through different kinds of sewage sludge.

PubMed

Torri, S I; Lavado, R S

2008-01-01

A greenhouse experiment was set up to study the distribution of Cd, Cu and Pb in three typical soils of the Pampas Region amended with sewage sludge. A sequential extraction procedure was used to obtain four operationally defined geochemical species: exchangeable, bound to organic matter, bound to carbonates, and residual. Two kinds of sewage sludge were used: pure sewage sludge and sewage sludge containing 30% DM of its own incinerated ash, at rates equivalent to a field application of 150 t DM ha(-1). Pots were maintained at 80% of field capacity through daily irrigation with distilled water. Soil samples were obtained on days 1, 60, 270 and 360, and then air-dried and passed through a 2 mm sieve for analysis. Results showed that sludge application increased the less available forms of Cd, Cu and Pb. The inorganic forms became the most prevalent forms for Cu and Pb, whereas Cd was only found in the residual fraction. The concentrations of OM-Cu and INOR-Cu in the amended soil samples were closely correlated with soil pH, whereas the chemical behavior of Cd and Pb did not depend on soil physico-chemical characteristics.

An Overview of Computational Aeroacoustic Modeling at NASA Langley

NASA Technical Reports Server (NTRS)

Lockard, David P.

2001-01-01

The use of computational techniques in the area of acoustics is known as computational aeroacoustics and has shown great promise in recent years. Although an ultimate goal is to use computational simulations as a virtual wind tunnel, the problem is so complex that blind applications of traditional algorithms are typically unable to produce acceptable results. The phenomena of interest are inherently unsteady and cover a wide range of frequencies and amplitudes. Nonetheless, with appropriate simplifications and special care to resolve specific phenomena, currently available methods can be used to solve important acoustic problems. These simulations can be used to complement experiments, and often give much more detailed information than can be obtained in a wind tunnel. The use of acoustic analogy methods to inexpensively determine far-field acoustics from near-field unsteadiness has greatly reduced the computational requirements. A few examples of current applications of computational aeroacoustics at NASA Langley are given. There remains a large class of problems that require more accurate and efficient methods. Research to develop more advanced methods that are able to handle the geometric complexity of realistic problems using block-structured and unstructured grids are highlighted.

The magnetic lead field theorem in the quasi-static approximation and its use for magnetoencephalography forward calculation in realistic volume conductors.

PubMed

Nolte, Guido

2003-11-21

The equation for the magnetic lead field for a given magnetoencephalography (MEG) channel is well known for arbitrary frequencies omega but is not directly applicable to MEG in the quasi-static approximation. In this paper we derive an equation for omega = 0 starting from the very definition of the lead field instead of using Helmholtz's reciprocity theorems. The results are (a) the transpose of the conductivity times the lead field is divergence-free, and (b) the lead field differs from the one in any other volume conductor by a gradient of a scalar function. Consequently, for a piecewise homogeneous and isotropic volume conductor, the lead field is always tangential at the outermost surface. Based on this theoretical result, we formulated a simple and fast method for the MEG forward calculation for one shell of arbitrary shape: we correct the corresponding lead field for a spherical volume conductor by a superposition of basis functions, gradients of harmonic functions constructed here from spherical harmonics, with coefficients fitted to the boundary conditions. The algorithm was tested for a prolate spheroid of realistic shape for which the analytical solution is known. For high order in the expansion, we found the solutions to be essentially exact and for reasonable accuracies much fewer multiplications are needed than in typical implementations of the boundary element methods. The generalization to more shells is straightforward.

Reconstruction of a Broadband Spectrum of Alfvenic Fluctuations

NASA Technical Reports Server (NTRS)

Vinas, Adolfo F.; Fuentes, Pablo S. M.; Araneda, Jaime A.; Maneva, Yana G.

2014-01-01

Alfvenic fluctuations in the solar wind exhibit a high degree of velocities and magnetic field correlations consistent with Alfven waves propagating away and toward the Sun. Two remarkable properties of these fluctuations are the tendencies to have either positive or negative magnetic helicity (-1 less than or equal to sigma(sub m) less than or equal to +1) associated with either left- or right- topological handedness of the fluctuations and to have a constant magnetic field magnitude. This paper provides, for the first time, a theoretical framework for reconstructing both the magnetic and velocity field fluctuations with a divergence-free magnetic field, with any specified power spectral index and normalized magnetic- and cross-helicity spectrum field fluctuations for any plasma species. The spectrum is constructed in the Fourier domain by imposing two conditions-a divergence-free magnetic field and the preservation of the sense of magnetic helicity in both spaces-as well as using Parseval's theorem for the conservation of energy between configuration and Fourier spaces. Applications to the one-dimensional spatial Alfvenic propagation are presented. The theoretical construction is in agreement with typical time series and power spectra properties observed in the solar wind. The theoretical ideas presented in this spectral reconstruction provide a foundation for more realistic simulations of plasma waves, solar wind turbulence, and the propagation of energetic particles in such fluctuating fields.

Functional gene diversity of soil microbial communities from five oil-contaminated fields in China.

PubMed

Liang, Yuting; Van Nostrand, Joy D; Deng, Ye; He, Zhili; Wu, Liyou; Zhang, Xu; Li, Guanghe; Zhou, Jizhong

2011-03-01

To compare microbial functional diversity in different oil-contaminated fields and to know the effects of oil contaminant and environmental factors, soil samples were taken from typical oil-contaminated fields located in five geographic regions of China. GeoChip, a high-throughput functional gene array, was used to evaluate the microbial functional genes involved in contaminant degradation and in other major biogeochemical/metabolic processes. Our results indicated that the overall microbial community structures were distinct in each oil-contaminated field, and samples were clustered by geographic locations. The organic contaminant degradation genes were most abundant in all samples and presented a similar pattern under oil contaminant stress among the five fields. In addition, alkane and aromatic hydrocarbon degradation genes such as monooxygenase and dioxygenase were detected in high abundance in the oil-contaminated fields. Canonical correspondence analysis indicated that the microbial functional patterns were highly correlated to the local environmental variables, such as oil contaminant concentration, nitrogen and phosphorus contents, salt and pH. Finally, a total of 59% of microbial community variation from GeoChip data can be explained by oil contamination, geographic location and soil geochemical parameters. This study provided insights into the in situ microbial functional structures in oil-contaminated fields and discerned the linkages between microbial communities and environmental variables, which is important to the application of bioremediation in oil-contaminated sites.

Functional gene diversity of soil microbial communities from five oil-contaminated fields in China

PubMed Central

Liang, Yuting; Van Nostrand, Joy D; Deng, Ye; He, Zhili; Wu, Liyou; Zhang, Xu; Li, Guanghe; Zhou, Jizhong

2011-01-01

To compare microbial functional diversity in different oil-contaminated fields and to know the effects of oil contaminant and environmental factors, soil samples were taken from typical oil-contaminated fields located in five geographic regions of China. GeoChip, a high-throughput functional gene array, was used to evaluate the microbial functional genes involved in contaminant degradation and in other major biogeochemical/metabolic processes. Our results indicated that the overall microbial community structures were distinct in each oil-contaminated field, and samples were clustered by geographic locations. The organic contaminant degradation genes were most abundant in all samples and presented a similar pattern under oil contaminant stress among the five fields. In addition, alkane and aromatic hydrocarbon degradation genes such as monooxygenase and dioxygenase were detected in high abundance in the oil-contaminated fields. Canonical correspondence analysis indicated that the microbial functional patterns were highly correlated to the local environmental variables, such as oil contaminant concentration, nitrogen and phosphorus contents, salt and pH. Finally, a total of 59% of microbial community variation from GeoChip data can be explained by oil contamination, geographic location and soil geochemical parameters. This study provided insights into the in situ microbial functional structures in oil-contaminated fields and discerned the linkages between microbial communities and environmental variables, which is important to the application of bioremediation in oil-contaminated sites. PMID:20861922

Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe1.64Ga0.36O3 oxide

NASA Astrophysics Data System (ADS)

Bhowmik, R. N.; Vijayasri, G.

2015-06-01

We have studied current-voltage (I-V) characteristics of α-Fe1.64Ga0.36O3, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔVP) 0.345(± 0.001) V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (˜500-700%), magnetoresistance (70-135 %) and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.

9. Southeast view interior, typical interior office, supervisor's office, room ...

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

9. Southeast view interior, typical interior office, supervisor's office, room 24A - Selfridge Field, Building No. 1050, Northwest corner of Doolittle Avenue & D Street; Harrison Township, Mount Clemens, Macomb County, MI

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms

NASA Astrophysics Data System (ADS)

Mirkovic, Djordje; Stepanian, Phillip M.; Kelly, Jeffrey F.; Chilson, Phillip B.

2016-10-01

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification.

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms

PubMed Central

Mirkovic, Djordje; Stepanian, Phillip M.; Kelly, Jeffrey F.; Chilson, Phillip B.

2016-01-01

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification. PMID:27762292

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms.

PubMed

Mirkovic, Djordje; Stepanian, Phillip M; Kelly, Jeffrey F; Chilson, Phillip B

2016-10-20

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification.

Virtual surgery in a (tele-)radiology framework.

PubMed

Glombitza, G; Evers, H; Hassfeld, S; Engelmann, U; Meinzer, H P

1999-09-01

This paper presents telemedicine as an extension of a teleradiology framework through tools for virtual surgery. To classify the described methods and applications, the research field of virtual reality (VR) is broadly reviewed. Differences with respect to technical equipment, methodological requirements and areas of application are pointed out. Desktop VR, augmented reality, and virtual reality are differentiated and discussed in some typical contexts of diagnostic support, surgical planning, therapeutic procedures, simulation and training. Visualization techniques are compared as a prerequisite for virtual reality and assigned to distinct levels of immersion. The advantage of a hybrid visualization kernel is emphasized with respect to the desktop VR applications that are subsequently shown. Moreover, software design aspects are considered by outlining functional openness in the architecture of the host system. Here, a teleradiology workstation was extended by dedicated tools for surgical planning through a plug-in mechanism. Examples of recent areas of application are introduced such as liver tumor resection planning, diagnostic support in heart surgery, and craniofacial surgery planning. In the future, surgical planning systems will become more important. They will benefit from improvements in image acquisition and communication, new image processing approaches, and techniques for data presentation. This will facilitate preoperative planning and intraoperative applications.

Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China, 2004-2010.

PubMed

Zhang, Xinyu; Xu, Zhiwei; Sun, Xiaomin; Dong, Wenyi; Ballantine, Deborah

2013-05-01

The nitrate-nitrogen (NO3(-)-N) concentrations from shallow groundwater wells situated in 29 of the Chinese Ecosystem Research Network field stations, representing typical agro- and forest ecosystems, were assessed using monitoring data collected between 2004 and 2010. Results from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater, and allow linkages between nitrate concentrations in groundwater and broad land use categories to be made. Results indicated that most of the NO3(-)-N concentrations in groundwater from the agro- and forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard: Quality Standard for Ground Water (< or = 20 mg/L). Over the study period, the average NO3(-)-N concentrations were significantly higher in agro-ecosystems (4.1 +/- 0.33 mg/L) than in forest ecosystems (0.5 +/- 0.04 mg/L). NO3(-)-N concentrations were relatively higher (> 10 mg N /L) in 10 of the 43 wells sampled in the agricultural ecosystems. These elevated concentrations occurred mainly in the Ansai, Yucheng, Linze, Fukang, Akesu, and Cele field sites, which were located in arid and semi-arid areas where irrigation rates are high. We suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.

Very Long Term Oxidation of Titanium Aluminides Investigated

NASA Technical Reports Server (NTRS)

Locci, Ivan E.; Brady, Michael P.; Smialek, James L.; Retallick, William B.

2000-01-01

Titanium aluminides (TiAl) are of great interest for intermediate-temperature (600 to 850 C) aerospace and power-generation applications because they offer significant weight savings over today's nickel alloys. TiAl alloys are being investigated for low-pressure turbine blade applications, exhaust nozzle components, and compressor cases in advanced subsonic and supersonic engines. Significant progress has been made in understanding the fundamental aspects of the oxidation behavior of binary TiAl alloys. However, most of this work has concentrated on short term (<1000 hr), high-temperature (900 to 1000 C) exposures. Also, there is not much data available in the literature regarding the oxidation behavior of the quaternary and higher order engineering alloys. This is especially true for the very long term, low-temperature conditions likely to be experienced during aerospace applications. An investigation at the NASA Glenn Research Center at Lewis Field was undertaken to characterize the long-term oxidation behavior of various model and advanced titanium aluminides for periods up to 7000 hr at 704 C in air using a high-resolution field emission scanning electron microscope. Also, a unique surface treatment technique developed to improve the oxidation resistance of TiAl was evaluated. The alloys included in this investigation are listed in the table. The table also shows typical alloy compositions and the specific weight changes and scale thickness measured for each alloy after exposure to 700 C for 7000 hr in air.

Integration of Kinect and Low-Cost Gnss for Outdoor Navigation

NASA Astrophysics Data System (ADS)

Pagliaria, D.; Pinto, L.; Reguzzoni, M.; Rossi, L.

2016-06-01

Since its launch on the market, Microsoft Kinect sensor has represented a great revolution in the field of low cost navigation, especially for indoor robotic applications. In fact, this system is endowed with a depth camera, as well as a visual RGB camera, at a cost of about 200. The characteristics and the potentiality of the Kinect sensor have been widely studied for indoor applications. The second generation of this sensor has been announced to be capable of acquiring data even outdoors, under direct sunlight. The task of navigating passing from an indoor to an outdoor environment (and vice versa) is very demanding because the sensors that work properly in one environment are typically unsuitable in the other one. In this sense the Kinect could represent an interesting device allowing bridging the navigation solution between outdoor and indoor. In this work the accuracy and the field of application of the new generation of Kinect sensor have been tested outdoor, considering different lighting conditions and the reflective properties of the emitted ray on different materials. Moreover, an integrated system with a low cost GNSS receiver has been studied, with the aim of taking advantage of the GNSS positioning when the satellite visibility conditions are good enough. A kinematic test has been performed outdoor by using a Kinect sensor and a GNSS receiver and it is here presented.

Patterning of polymer nanofiber meshes by electrospinning for biomedical applications

PubMed Central

Neves, Nuno M; Campos, Rui; Pedro, Adriano; Cunha, José; Macedo, Francisco; Reis, Rui L

2007-01-01

The end-product of the electrospinning process is typically a randomly aligned fiber mesh or membrane. This is a result of the electric field generated between the drop of polymer solution at the needle and the collector. The developed electric field causes the stretching of the fibers and their random deposition. By judicious selection of the collector architecture, it is thus possible to develop other morphologies on the nanofiber meshes. The aim of this work is to prepare fiber meshes using various patterned collectors with specific dimensions and designs and to evaluate how those patterns can affect the properties of the meshes relevant to biomedical applications. This study aims at verifying whether it is possible to control the architecture of the fiber meshes by tailoring the geometry of the collector. Three different metallic collector topographies are used to test this hypothesis. Electrospun nonwoven patterned meshes of polyethylene oxide (PEO) and poly(ε-capro-lactone) (PCL) were successfully prepared. Those fiber meshes were analyzed by scanning electron microscopy (SEM). Both mechanical properties of the meshes and cell contacting experiments were performed to test the effect of the produced patterns over the properties of the meshes relevant for biomedical applications. The present study will evaluate cell adhesion sensitivity to the patterns generated and the effect of those patterns on the tensile properties of the fiber meshes. PMID:18019842

Tissue engineering and regenerative medicine: manufacturing challenges.

PubMed

Williams, D J; Sebastine, I M

2005-12-01

Tissue engineering and regenerative medicine are interdisciplinary fields that apply principles of engineering and life sciences to develop biological substitutes, typically composed of biological and synthetic components, that restore, maintain or improve tissue function. Many tissue engineering technologies are still at a laboratory or pre-commercial scale. The short review paper describes the most significant manufacturing and bio-process challenges inherent in the commercialisation and exploitation of the exciting results emerging from the biological and clinical laboratories exploring tissue engineering and regenerative medicine. A three-generation road map of the industry has been used to structure a view of these challenges and to define where the manufacturing community can contribute to the commercial success of the products from these emerging fields. The first-generation industry is characterised by its demonstrated clinical applications and products in the marketplace, the second is characterised by emerging clinical applications, and the third generation is characterised by aspirational clinical applications. The paper focuses on the cost reduction requirement of the first generation of the industry to allow more market penetration and consequent patient impact. It indicates the technological requirements, for instance the creation of three-dimensional tissue structures, and value chain issues in the second generation of the industry. The third-generation industry challenges lie in fundamental biological and clinical science. The paper sets out a road map of these generations to identify areas for research.

Liquid crystal 'blue phases' with a wide temperature range.

PubMed

Coles, Harry J; Pivnenko, Mikhail N

2005-08-18

Liquid crystal 'blue phases' are highly fluid self-assembled three-dimensional cubic defect structures that exist over narrow temperature ranges in highly chiral liquid crystals. The characteristic period of these defects is of the order of the wavelength of visible light, and they give rise to vivid specular reflections that are controllable with external fields. Blue phases may be considered as examples of tuneable photonic crystals with many potential applications. The disadvantage of these materials, as predicted theoretically and proved experimentally, is that they have limited thermal stability: they exist over a small temperature range (0.5-2 degrees C) between isotropic and chiral nematic (N*) thermotropic phases, which limits their practical applicability. Here we report a generic family of liquid crystals that demonstrate an unusually broad body-centred cubic phase (BP I*) from 60 degrees C down to 16 degrees C. We prove this with optical texture analysis, selective reflection spectroscopy, Kössel diagrams and differential scanning calorimetry, and show, using a simple polarizer-free electro-optic cell, that the reflected colour is switched reversibly in applied electric fields over a wide colour range in typically 10 ms. We propose that the unusual behaviour of these blue phase materials is due to their dimeric molecular structure and their very high flexoelectric coefficients. This in turn sets out new theoretical challenges and potentially opens up new photonic applications.

Phase in Optical Image Processing

NASA Astrophysics Data System (ADS)

Naughton, Thomas J.

2010-04-01

The use of phase has a long standing history in optical image processing, with early milestones being in the field of pattern recognition, such as VanderLugt's practical construction technique for matched filters, and (implicitly) Goodman's joint Fourier transform correlator. In recent years, the flexibility afforded by phase-only spatial light modulators and digital holography, for example, has enabled many processing techniques based on the explicit encoding and decoding of phase. One application area concerns efficient numerical computations. Pushing phase measurement to its physical limits, designs employing the physical properties of phase have ranged from the sensible to the wonderful, in some cases making computationally easy problems easier to solve and in other cases addressing mathematics' most challenging computationally hard problems. Another application area is optical image encryption, in which, typically, a phase mask modulates the fractional Fourier transformed coefficients of a perturbed input image, and the phase of the inverse transform is then sensed as the encrypted image. The inherent linearity that makes the system so elegant mitigates against its use as an effective encryption technique, but we show how a combination of optical and digital techniques can restore confidence in that security. We conclude with the concept of digital hologram image processing, and applications of same that are uniquely suited to optical implementation, where the processing, recognition, or encryption step operates on full field information, such as that emanating from a coherently illuminated real-world three-dimensional object.

Facile morphology-controlled synthesis of nickel-coated graphite core-shell particles for excellent conducting performance of polymer-matrix composites and enhanced catalytic reduction of 4-nitrophenol

NASA Astrophysics Data System (ADS)

Bian, Juan; Lan, Fang; Wang, Yilong; Ren, Ke; Zhao, Suling; Li, Wei; Chen, Zhihong; Li, Jiangyu; Guan, Jianguo

2018-04-01

We have developed a novel seed-mediated growth method to fabricate nickel-coated graphite composite particles (GP@Ni-CPs) with controllable shell morphology by simply adjusting the concentration of sodium hydroxide ([NaOH]). The fabrication of two kinds of typical GP@Ni-CPs includes adsorption of Ni2+ via electrostatic attraction, sufficient heterogeneous nucleation of Ni atoms by an in situ reduction, and shell-controlled growth by regulating the kinetics of electroless Ni plating in turn. High [NaOH] results in fast kinetics of electroless plating, which causes heterogeneous nuclei to grow isotropically. After fast and uniform growth of Ni nuclei, GP@Ni-CPs with dense shells can be achieved. The first typical GP@Ni-CPs exhibit denser shells, smaller diameters and higher conductivities than the available commercial ones, indicating their important applications in the conducting of polymer-matrix composites. On the other hand, low [NaOH] favors slow kinetics. Thus, the reduction rate of Ni2+ slows down to a relatively low level so that electroless plating is dominated thermodynamically instead of kinetically, leading to an anisotropic crystalline growth of nuclei and finally to the formation of GP@Ni-CPs with nanoneedle-like shells. The second typical samples can effectively catalyze the reduction of p-nitrophenol into p-aminophenol with NaBH4 in comparison with commercial GP@Ni-CPs and RANEY® Ni, owing to the strong charge accumulation effect of needle-like Ni shells. This work proposes a model system for fundamental investigations and has important applications in the fields of electronic interconnection and catalysis.

Three-photon absorption process in organic dyes enhanced by surface plasmon resonance

NASA Astrophysics Data System (ADS)

Cohanoschi, Ion

2006-07-01

Multi-photon absorption processes have received significant attention from the scientific community during the last decade, mainly because of their potential applications in optical limiting, data storage and biomedical fields. Perhaps, one of the most investigated processes studied so far has been two-photon absorption (2PA). These investigations have resulted in successful applications in all the fields mentioned above. However, 2PA present some limitations in the biomedical field when pumping at typical 2PA wavelengths. In order to overcome these limitations, three-photon absorption (3PA) process has been proposed. However, 3PA in organic molecules has a disadvantage, typical values of sigma3' are small (10-81 cm6s 2/photon2), therefore, 3PA excitation requires high irradiances to induce the promotion of electrons from the ground state to the final excited state. To overcome this obstacle, specific molecules that exhibit large 3PA cross-section must be designed. Thus far, there is a lack of systematic studies that correlate 3PA processes with the molecular structure of organic compounds. In order to fill the existent gap in 3PA molecular engineering, in this dissertation we have investigated the structure/property relationship for a new family of fluorene derivatives with very high three-photon absorption cross-sections. We demonstrated that the symmetric intramolecular charge transfer as well as the pi-electron conjugation length enhances the 3PA cross-section of fluorene derivatives. In addition, we showed that the withdrawing electron character of the attractor groups in a pull-pull geometry proved greater 3PA cross-section. After looking for alternative ways to enhance the effective sigma 3' of organic molecules, we investigated the enhancement of two- and three-photon absorption processes by means of Surface Plasmon. We demonstrated an enhancement of the effective two- and three-photon absorption cross-section of an organic compound of 480 and 30 folds, respectively. We proved that the enhancement is a direct consequence of the electric field enhancement at a metal/buffer interface. Next, motivated by the demands for new materials with enhanced nonlinear optical properties, we studied the 3PA of Hematoporphyrin IX and J-aggregate supramolecular systems. As a result, we were able to propose the use of 3PA in photodynamic therapy using Photofrin, the only drug approved by the FDA for PDT.

Building a virtual ligand screening pipeline using free software: a survey.

PubMed

Glaab, Enrico

2016-03-01

Virtual screening, the search for bioactive compounds via computational methods, provides a wide range of opportunities to speed up drug development and reduce the associated risks and costs. While virtual screening is already a standard practice in pharmaceutical companies, its applications in preclinical academic research still remain under-exploited, in spite of an increasing availability of dedicated free databases and software tools. In this survey, an overview of recent developments in this field is presented, focusing on free software and data repositories for screening as alternatives to their commercial counterparts, and outlining how available resources can be interlinked into a comprehensive virtual screening pipeline using typical academic computing facilities. Finally, to facilitate the set-up of corresponding pipelines, a downloadable software system is provided, using platform virtualization to integrate pre-installed screening tools and scripts for reproducible application across different operating systems. © The Author 2015. Published by Oxford University Press.

Building a virtual ligand screening pipeline using free software: a survey

PubMed Central

2016-01-01

Virtual screening, the search for bioactive compounds via computational methods, provides a wide range of opportunities to speed up drug development and reduce the associated risks and costs. While virtual screening is already a standard practice in pharmaceutical companies, its applications in preclinical academic research still remain under-exploited, in spite of an increasing availability of dedicated free databases and software tools. In this survey, an overview of recent developments in this field is presented, focusing on free software and data repositories for screening as alternatives to their commercial counterparts, and outlining how available resources can be interlinked into a comprehensive virtual screening pipeline using typical academic computing facilities. Finally, to facilitate the set-up of corresponding pipelines, a downloadable software system is provided, using platform virtualization to integrate pre-installed screening tools and scripts for reproducible application across different operating systems. PMID:26094053

Smart Electrospun Nanofibers for Controlled Drug Release: Recent Advances and New Perspectives

PubMed Central

Weng, Lin; Xie, Jingwei

2017-01-01

In biological systems, chemical molecules or ions often release upon certain conditions, at a specific location, and over a desired period of time. Electrospun nanofibers that undergo alterations in the physicochemical characteristics corresponding to environmental changes have gained considerable interest for various applications. Inspired by biological systems, therapeutic molecules have been integrated with these smart electrospun nanofibers, presenting activation-modulated or feedback-regulated control of drug release. Compared to other materials like smart hydrogels, environment-responsive nanofiber-based drug delivery systems are relatively new but possess incomparable advantages due to their greater permeability, which allows shorter response time and more precise control over the release rate. In this article, we review the mechanisms of various environmental parameters functioning as stimuli to tailor the release rates of smart electrospun nanofibers. We also illustrate several typical examples in specific applications. We conclude this article with a discussion on perspectives and future possibilities in this field. PMID:25732665

Bottom-Up Engineering of Well-Defined 3D Microtissues Using Microplatforms and Biomedical Applications.

PubMed

Lee, Geon Hui; Lee, Jae Seo; Wang, Xiaohong; Lee, Sang Hoon

2016-01-07

During the last decades, the engineering of well-defined 3D tissues has attracted great attention because it provides in vivo mimicking environment and can be a building block for the engineering of bioartificial organs. In this Review, diverse engineering methods of 3D tissues using microscale devices are introduced. Recent progress of microtechnologies has enabled the development of microplatforms for bottom-up assembly of diverse shaped 3D tissues consisting of various cells. Micro hanging-drop plates, microfluidic chips, and arrayed microwells are the typical examples. The encapsulation of cells in hydrogel microspheres and microfibers allows the engineering of 3D microtissues with diverse shapes. Applications of 3D microtissues in biomedical fields are described, and the future direction of microplatform-based engineering of 3D micro-tissues is discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Literature Review: Theory and Application of In-Line Inspection Technologies for Oil and Gas Pipeline Girth Weld Defection

PubMed Central

Feng, Qingshan; Li, Rui; Nie, Baohua; Liu, Shucong; Zhao, Lianyu; Zhang, Hong

2016-01-01

Girth weld cracking is one of the main failure modes in oil and gas pipelines; girth weld cracking inspection has great economic and social significance for the intrinsic safety of pipelines. This paper introduces the typical girth weld defects of oil and gas pipelines and the common nondestructive testing methods, and systematically generalizes the progress in the studies on technical principles, signal analysis, defect sizing method and inspection reliability, etc., of magnetic flux leakage (MFL) inspection, liquid ultrasonic inspection, electromagnetic acoustic transducer (EMAT) inspection and remote field eddy current (RFDC) inspection for oil and gas pipeline girth weld defects. Additionally, it introduces the new technologies for composite ultrasonic, laser ultrasonic, and magnetostriction inspection, and provides reference for development and application of oil and gas pipeline girth weld defect in-line inspection technology. PMID:28036016

Graphene-based smart materials

NASA Astrophysics Data System (ADS)

Yu, Xiaowen; Cheng, Huhu; Zhang, Miao; Zhao, Yang; Qu, Liangti; Shi, Gaoquan

2017-09-01

The high specific surface area and the excellent mechanical, electrical, optical and thermal properties of graphene make it an attractive component for high-performance stimuli-responsive or 'smart' materials. Complementary to these inherent properties, functionalization or hybridization can substantially improve the performance of these materials. Typical graphene-based smart materials include mechanically exfoliated perfect graphene, chemical vapour deposited high-quality graphene, chemically modified graphene (for example, graphene oxide and reduced graphene oxide) and their macroscopic assemblies or composites. These materials are sensitive to a range of stimuli, including gas molecules or biomolecules, pH value, mechanical strain, electrical field, and thermal or optical excitation. In this Review, we outline different graphene-based smart materials and their potential applications in actuators, chemical or strain sensors, self-healing materials, photothermal therapy and controlled drug delivery. We also introduce the working mechanisms of graphene-based smart materials and discuss the challenges facing the realization of their practical applications.

Smart electrospun nanofibers for controlled drug release: recent advances and new perspectives.

PubMed

Weng, Lin; Xie, Jingwei

2015-01-01

In biological systems, chemical molecules or ions often release upon certain conditions, at a specific location, and over a desired period of time. Electrospun nanofibers that undergo alterations in the physicochemical characteristics corresponding to environmental changes have gained considerable interest for various applications. Inspired by biological systems, therapeutic molecules have been integrated with these smart electrospun nanofibers, presenting activation-modulated or feedback-regulated control of drug release. Compared to other materials like smart hydrogels, environment-responsive nanofiber-based drug delivery systems are relatively new but possess incomparable advantages due to their greater permeability, which allows shorter response time and more precise control over the release rate. In this article, we review the mechanisms of various environmental parameters functioning as stimuli to tailor the release rates of smart electrospun nanofibers. We also illustrate several typical examples in specific applications. We conclude this article with a discussion on perspectives and future possibilities in this field.

Microfiber Optical Sensors: A Review

PubMed Central

Lou, Jingyi; Wang, Yipei; Tong, Limin

2014-01-01

With diameter close to or below the wavelength of guided light and high index contrast between the fiber core and the surrounding, an optical microfiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, evanescent fields and waveguide dispersion. Among various microfiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, fast response, high flexibility and low optical power consumption. Here we review recent progress in microfiber optical sensors regarding their fabrication, waveguide properties and sensing applications. Typical microfiber-based sensing structures, including biconical tapers, optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, are summarized. Categorized by sensing structures, microfiber optical sensors for refractive index, concentration, temperature, humidity, strain and current measurement in gas or liquid environments are reviewed. Finally, we conclude with an outlook for challenges and opportunities of microfiber optical sensors. PMID:24670720

Game Theory for Wireless Sensor Networks: A Survey

PubMed Central

Shi, Hai-Yan; Wang, Wan-Liang; Kwok, Ngai-Ming; Chen, Sheng-Yong

2012-01-01

Game theory (GT) is a mathematical method that describes the phenomenon of conflict and cooperation between intelligent rational decision-makers. In particular, the theory has been proven very useful in the design of wireless sensor networks (WSNs). This article surveys the recent developments and findings of GT, its applications in WSNs, and provides the community a general view of this vibrant research area. We first introduce the typical formulation of GT in the WSN application domain. The roles of GT are described that include routing protocol design, topology control, power control and energy saving, packet forwarding, data collection, spectrum allocation, bandwidth allocation, quality of service control, coverage optimization, WSN security, and other sensor management tasks. Then, three variations of game theory are described, namely, the cooperative, non-cooperative, and repeated schemes. Finally, existing problems and future trends are identified for researchers and engineers in the field. PMID:23012533

Exploring methods to expedite the recording of CEST datasets using selective pulse excitation

NASA Astrophysics Data System (ADS)

Yuwen, Tairan; Bouvignies, Guillaume; Kay, Lewis E.

2018-07-01

Chemical Exchange Saturation Transfer (CEST) has emerged as a powerful tool for studies of biomolecular conformational exchange involving the interconversion between a major, visible conformer and one or more minor, invisible states. Applications typically entail recording a large number of 2D datasets, each of which differs in the position of a weak radio frequency field, so as to generate a CEST profile for each nucleus from which the chemical shifts of spins in the invisible state(s) are obtained. Here we compare a number of band-selective CEST schemes for speeding up the process using either DANTE or cosine-modulated excitation approaches. We show that while both are essentially identical for applications such as 15N CEST, in cases where the probed spins are dipolar or scalar coupled to other like spins there can be advantages for the cosine-excitation scheme.

Application Of Interferometry To Optical Components And Systems Evaluation

NASA Astrophysics Data System (ADS)

Houston, Joseph B., Jr.

1982-05-01

Interferometry provides opticians and lens designers with the ability to evaluate optical components and systems quantitatively. A variety of interferometers and interferometric test procedures have evolved over the past several decades. This evolution has stimulated an ever-increasing amount of interest in using a new generation of instrumentation and computer software for solving cost and schedule problems both in the shop and at field test sites. Optical engineers and their customers continue to gain confidence in their abilities to perform several operations such as assure component quality, analyze and optimize lens assemblies, and accurately predict end-item performance. In this paper, a set of typical test situations are addressed and some standard instrumentation is described, as a means of illustrating the special advantages of interferometric testing. Emphasis will be placed on the proper application of currently available hardware and some of the latest proven techniques.

Plasma-enhanced pulsed-laser deposition of single-crystalline M o2C ultrathin superconducting films

NASA Astrophysics Data System (ADS)

Zhang, Fan; Zhang, Zhi; Wang, Huichao; Chan, Cheuk Ho; Chan, Ngai Yui; Chen, Xin Xin; Dai, Ji-Yan

2017-08-01

Transition-metal carbides (TMCs) possess many intriguing properties and inspiring application potentials, and recently the study of a two-dimensional form of TMCs has attracted great attention. Herein, we report successful fabrication of continuous M o2C ultrathin single-crystalline films at 700 ∘C with an approach of plasma-enhanced pulsed-laser deposition. By sophisticated structural analyses, the M o2C films are characterized as single crystal with a rarely reported face-centered cubic structure. In further electrical transport measurements, superconductivity observed in the M o2C films demonstrates a typical two-dimensional feature, which is consistent with Berezinskii-Kosterlitz-Thouless transitions. Besides, large upper critical magnetic fields are discovered in this system. Our work offers an approach to grow large-area and high-quality TMCs at relatively low temperatures. This study may stimulate more related investigations on the synthesis, characterizations, and applications of two-dimensional TMCs.

Microwave assisted growth of nanorods vanadium dioxide VO2 (R): structural and electrical properties

NASA Astrophysics Data System (ADS)

Derkaoui, I.; Khenfouch, M.; Mothudi, B. M.; Moloi, S. J.; Zorkani, I.; Jorio, A.; Maaza, M.

2018-03-01

Nanostructured metal oxides have attracted a lot of attention recently owning to their unique structural advantages and demonstrated promising chemical and physical properties for various applications. In this study, we report the structural and electrical properties of vanadium dioxide VO2 (R) prepared via a single reaction microwave (SRC) synthesis. Our results are revealing that the components of VO2 (R) films have a rod-like shape with a uniform size distribution. The nanorods with very smooth and flat surfaces have a typical length of up to 2μm and a width of about several nanometers. The structural investigations reveal the high crystallinity of VO2 (R) ensuring good electrical contact and showing a high conductivity as a function of temperature. This synthesis method provides a new simple route to fabricate one-dimensional nanostructured metal oxides which is suitable for a large field of applications especially for smart windows.

Implementation of Multispectral Image Classification on a Remote Adaptive Computer

NASA Technical Reports Server (NTRS)

Figueiredo, Marco A.; Gloster, Clay S.; Stephens, Mark; Graves, Corey A.; Nakkar, Mouna

1999-01-01

As the demand for higher performance computers for the processing of remote sensing science algorithms increases, the need to investigate new computing paradigms its justified. Field Programmable Gate Arrays enable the implementation of algorithms at the hardware gate level, leading to orders of m a,gnitude performance increase over microprocessor based systems. The automatic classification of spaceborne multispectral images is an example of a computation intensive application, that, can benefit from implementation on an FPGA - based custom computing machine (adaptive or reconfigurable computer). A probabilistic neural network is used here to classify pixels of of a multispectral LANDSAT-2 image. The implementation described utilizes Java client/server application programs to access the adaptive computer from a remote site. Results verify that a remote hardware version of the algorithm (implemented on an adaptive computer) is significantly faster than a local software version of the same algorithm implemented on a typical general - purpose computer).

Measurements of magnetic spin excitations in Permalloy microstructures using nitrogen-vacancy magnetometry

NASA Astrophysics Data System (ADS)

Liu, H. J. Jason; Yoon, Seungha; McMichael, Robert

The magnetic properties of nitrogen-vacancy (NV) centers in diamond have enabled emerging applications in fields ranging from cell biology to quantum computing. An NV center is a lattice defect, which behaves like a spin-1 system. NV centers can be prepared in the mz = 0 state by excitation with green light, and the spin state can be detected by the center's fluorescence of red light. The Zeeman splitting of the mz = +/-1 state, combined with a spin coherence time that can approach 1 ms, makes the NV center a sensitive, atom-sized magnetometer. Recently, NV centers have been used to measure spin wave excitations and vortex core dynamics in a Permalloy microdisk. In this talk, we present current NV center measurements on Permalloy micro and nanostructures that build on previous work. Permalloy structures were fabricated on top of a microstrip antenna and the measurements were conducted on a home-built confocal microscope. Preliminary measurements show photoluminescence contrast of ~12% and field detectivity on the order of µT/Hz1/2. This allows for fine field mapping of stray magnetic fields produced by micro and nanostructures, which are typically a few milliteslas in magnitude. Maryland Nanocenter, University of Maryland.

Effects of land use on surface-water quality in the East Everglades, Dade County, Florida

USGS Publications Warehouse

Waller, Bradley G.

1982-01-01

Water-quality characteristics were determined at five developed areas in the East Everglades, Dade County, Florida, during the 1978 wet season (June through October). These areas are designated as: Coopertown; Chekika Hammock State Park; residential area; rock-plowed tomato field; and Cracker Jack Slough agricultural area. Data from the developed areas were compared with data from four baseline sites in undeveloped areas to determine the effects of land use on the surface-water quality. The rock-plowed tomato field was the only area where surface-water quality was affected. Water quality at this field is affected by agricultural activities and chemical applications as indicated by increased concentrations of orthophosphate, organic nitrogen, organic carbon, copper, manganese, mercury, and potassium. The remaining four areas of land use had water-quality characteristics typical of baseline sites in nearby Northeast Shark River Slough or Taylor Slough. Chemical analyses of soil indicated chlorinated-hydrocarbon insecticide residues at Coopertown and the two agricultural areas, Cracker Jack Slough and the rock-plowed tomato field. Trace elements in concentrations greater than base level occurred at both agricultural areas (manganese), Chekika Hammock State Park (manganese), and at Coopertown (lead and zinc). (USGS)

Characterization of Hard Piezoelectric Lead-Free Ceramics

PubMed Central

Zhang, Shujun; Lim, Jong Bong; Lee, Hyeong Jae; Shrout, Thomas R.

2010-01-01

K4CuNb8O23 doped K0.45Na0.55NbO3 (KNN-KCN) ferroelectric ceramics were found to exhibit asymmetrical polarization hysteresis loops, related to the development of an internal bias field. The internal bias field is believed to be the result of defect dipoles of acceptor ions and oxygen vacancies, which lead to piezoelectric “hardening” effect, by stabilizing and pinning of the domain wall motion. The dielectric loss for the hard lead-free piezoelectric ceramic was found to be 0.6%, with mechanical quality factors Q on the order of >1500. Furthermore, the piezoelectric properties were found to decrease and the coercive field increased, when compared with the undoped material, exhibiting a typical characteristic of “hard” behavior. The temperature usage range was limited by the polymorphic phase transition temperature, being 188°C. The full set of material constants was determined for the KNN-KCN materials. Compared with conventional hard PZT ceramics, the lead-free possessed lower dielectric and piezoelectric properties; however, comparable values of mechanical Q, dielectric loss, and coercive fields were obtained, making acceptor modified KNN based lead-free piezoelectric material promising for high-power applications, where lead-free materials are desirable. PMID:19686966

3D Field Modifications of Core Neutral Fueling In the EMC3-EIRENE Code

NASA Astrophysics Data System (ADS)

Waters, Ian; Frerichs, Heinke; Schmitz, Oliver; Ahn, Joon-Wook; Canal, Gustavo; Evans, Todd; Feng, Yuehe; Kaye, Stanley; Maingi, Rajesh; Soukhanovskii, Vsevolod

2017-10-01

The application of 3-D magnetic field perturbations to the edge plasmas of tokamaks has long been seen as a viable way to control damaging Edge Localized Modes (ELMs). These 3-D fields have also been correlated with a density drop in the core plasmas of tokamaks; known as `pump-out'. While pump-out is typically explained as the result of enhanced outward transport, degraded fueling of the core may also play a role. By altering the temperature and density of the plasma edge, 3-D fields will impact the distribution function of high energy neutral particles produced through ion-neutral energy exchange processes. Starved of the deeply penetrating neutral source, the core density will decrease. Numerical studies carried out with the EMC3-EIRENE code on National Spherical Tokamak eXperiment-Upgrade (NSTX-U) equilibria show that this change to core fueling by high energy neutrals may be a significant contributor to the overall particle balance in the NSTX-U tokamak: deep core (Ψ < 0.5) fueling from neutral ionization sources is decreased by 40-60% with RMPs. This work was funded by the US Department of Energy under Grant DE-SC0012315.

Broadband X-ray Imaging in the Near-Field Region of an Airblast Atomizer

NASA Astrophysics Data System (ADS)

Li, Danyu; Bothell, Julie; Morgan, Timothy; Heindel, Theodore

2017-11-01

The atomization process has a close connection to the efficiency of many spray applications. Examples include improved fuel atomization increasing the combustion efficiency of aircraft engines, or controlled droplet size and spray angle enhancing the quality and speed of the painting process. Therefore, it is vital to understand the physics of the atomization process, but the near-field region is typically optically dense and difficult to probe with laser-based or intrusive measurement techniques. In this project, broadband X-ray radiography and X-ray computed tomography (CT) imaging were performed in the near-field region of a canonical coaxial airblast atomizer. The X-ray absorption rate was enhanced by adding 20% by weight of Potassium Iodide to the liquid phase to increase image contrast. The radiographs provided an estimate of the liquid effective mean path length and spray angle at the nozzle exit for different flow conditions. The reconstructed CT images provided a 3D map of the time-average liquid spray distribution. X-ray imaging was used to quantify the changes in the near-field spray characteristics for various coaxial airblast atomizer flow conditions. Office of Naval Research.