Science.gov

Sample records for high intensity led

  1. Inhibition of enteric pathogens using integrated high intensity 405 nm LED on the surface of almonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The disinfecting properties of 405 nm light were investigated against Escherichia coli O157:H7, Salmonella, and their non-pathogenic surrogates inoculated onto the surface of almonds. High intensity monochromatic light was generated from an array of narrow-band 405 nm light emitting diodes (LED). Al...

  2. Inhibition of enteric pathogens and surrogates using integrated, high intensity 405nm led light on the surface of almonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The disinfecting properties of 405 nm light were investigated against Escherichia coli O157:H7, Salmonella, and their non-pathogenic surrogate bacteria on the surface of almonds. High intensity monochromatic blue light (MBL) was generated from an array of narrow-band 405 nm light-emitting diodes (LE...

  3. Multicolor, High Efficiency, Nanotextured LEDs

    SciTech Connect

    Jung Han; Arto Nurmikko

    2011-09-30

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and green for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) heteroepitaxy of nitrogen-polar LEDs on sapphire, (ii) heteroepitaxy of semipolar (11{bar 2}2) green LEDs on sapphire, (iii) synthesis of quantum-dot loaded nanoporous GaN that emits white light without phosphor conversion, (iv) demonstration of the highest quality semipolar (11{bar 2}2) GaN on sapphire using orientation-controlled epitaxy, (v) synthesis of nanoscale GaN and InGaN medium, and (vi) development of a novel liftoff process for manufacturing GaN thin-film vertical LEDs. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  4. Intensity estimation method of LED array for visible light communication

    NASA Astrophysics Data System (ADS)

    Ito, Takanori; Yendo, Tomohiro; Arai, Shintaro; Yamazato, Takaya; Okada, Hiraku; Fujii, Toshiaki

    2013-03-01

    This paper focuses on a road-to-vehicle visible light communication (VLC) system using LED traffic light as the transmitter and camera as the receiver. The traffic light is composed of a hundred of LEDs on two dimensional plain. In this system, data is sent as two dimensional brightness patterns by controlling each LED of the traffic light individually, and they are received as images by the camera. Here, there are problems that neighboring LEDs on the received image are merged due to less number of pixels in case that the receiver is distant from the transmitter, and/or due to blurring by defocus of the camera. Because of that, bit error rate (BER) increases due to recognition error of intensity of LEDs To solve the problem, we propose a method that estimates the intensity of LEDs by solving the inverse problem of communication channel characteristic from the transmitter to the receiver. The proposed method is evaluated by BER characteristics which are obtained by computer simulation and experiments. In the result, the proposed method can estimate with better accuracy than the conventional methods, especially in case that the received image is blurred a lot, and the number of pixels is small.

  5. Development of lighting system for hologram using high power LEDs

    NASA Astrophysics Data System (ADS)

    Baba, Junko; Yaeda, Asami; Asakawa, Hisashi; Shibuya, Takehisa; Wakaki, Moriaki

    2007-02-01

    Light emitting diode (LED) became popular rapidly by the appearance of blue LED. Three color (R, G, B) emitting LEDs are utilized for the image display system by the development of multi color emitting LED. White LEDs became to commercial base by combining blue or UV light sources for excitation and materials for fluorescence. White LEDs are prevailing for general lighting applications. A single tip with the power of 5W became line up for commercial market owing to the research for high intensity LEDs. As a result, LEDs are replacing the market of conventional incandescent lighting and even head lights of the automobile. In this study, we aim to fabricate the white and R, G, B lighting system using high brightness LEDs for the lighting of holograms instead of a conventional halogen lamp.

  6. High Power UV LED Industrial Curing Systems

    SciTech Connect

    Karlicek, Robert, F., Jr; Sargent, Robert

    2012-05-14

    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  7. High-power LED package requirements

    NASA Astrophysics Data System (ADS)

    Wall, Frank; Martin, Paul S.; Harbers, Gerard

    2004-01-01

    Power LEDs have evolved from simple indicators into illumination devices. For general lighting applications, where the objective is to light up an area, white LED arrays have been utilized to serve that function. Cost constraints will soon drive the industry to provide a discrete lighting solution. Early on, that will mean increasing the power densities while quantum efficiencies are addressed. For applications such as automotive headlamps & projection, where light needs to be tightly collimated, or controlled, arrays of die or LEDs will not be able to satisfy the requirements & limitations defined by etendue. Ultimately, whether a luminaire requires a small source with high luminance, or light spread over a general area, economics will force the evolution of the illumination LED into a compact discrete high power package. How the customer interfaces with this new package should be an important element considered early on in the design cycle. If an LED footprint of adequate size is not provided, it may prove impossible for the customer, or end user, to get rid of the heat in a manner sufficient to prevent premature LED light output degradation. Therefore it is critical, for maintaining expected LED lifetime & light output, that thermal performance parameters be defined, by design, at the system level, which includes heat sinking methods & interface materials or methdology.

  8. LED intense headband light source for fingerprint analysis

    DOEpatents

    Villa-Aleman, Eliel

    2005-03-08

    A portable, lightweight and high-intensity light source for detecting and analyzing fingerprints during field investigation. On-site field analysis requires long hours of mobile analysis. In one embodiment, the present invention comprises a plurality of light emitting diodes; a power source; and a personal attachment means; wherein the light emitting diodes are powered by the power source, and wherein the power source and the light emitting diodes are attached to the personal attachment means to produce a personal light source for on-site analysis of latent fingerprints. The present invention is available for other applications as well.

  9. White LED with High Package Extraction Efficiency

    SciTech Connect

    Yi Zheng; Matthew Stough

    2008-09-30

    The goal of this project is to develop a high efficiency phosphor converting (white) Light Emitting Diode (pcLED) 1-Watt package through an increase in package extraction efficiency. A transparent/translucent monolithic phosphor is proposed to replace the powdered phosphor to reduce the scattering caused by phosphor particles. Additionally, a multi-layer thin film selectively reflecting filter is proposed between blue LED die and phosphor layer to recover inward yellow emission. At the end of the project we expect to recycle approximately 50% of the unrecovered backward light in current package construction, and develop a pcLED device with 80 lm/W{sub e} using our technology improvements and commercially available chip/package source. The success of the project will benefit luminous efficacy of white LEDs by increasing package extraction efficiency. In most phosphor-converting white LEDs, the white color is obtained by combining a blue LED die (or chip) with a powdered phosphor layer. The phosphor partially absorbs the blue light from the LED die and converts it into a broad green-yellow emission. The mixture of the transmitted blue light and green-yellow light emerging gives white light. There are two major drawbacks for current pcLEDs in terms of package extraction efficiency. The first is light scattering caused by phosphor particles. When the blue photons from the chip strike the phosphor particles, some blue light will be scattered by phosphor particles. Converted yellow emission photons are also scattered. A portion of scattered light is in the backward direction toward the die. The amount of this backward light varies and depends in part on the particle size of phosphors. The other drawback is that yellow emission from phosphor powders is isotropic. Although some backward light can be recovered by the reflector in current LED packages, there is still a portion of backward light that will be absorbed inside the package and further converted to heat. Heat

  10. High-power LEDs for plant cultivation

    NASA Astrophysics Data System (ADS)

    Tamulaitis, Gintautas; Duchovskis, Pavelas; Bliznikas, Zenius; Breive, Kestutis; Ulinskaite, Raimonda; Brazaityte, Ausra; Novickovas, Algirdas; Zukauskas, Arturas; Shur, Michael S.

    2004-10-01

    We report on high-power solid-state lighting facility for cultivation of greenhouse vegetables and on the results of the study of control of photosynthetic activity and growth morphology of radish and lettuce imposed by variation of the spectral composition of illumination. Experimental lighting modules (useful area of 0.22 m2) were designed based on 4 types of high-power light-emitting diodes (LEDs) with emission peaked in red at the wavelengths of 660 nm and 640 nm (predominantly absorbed by chlorophyll a and b for photosynthesis, respectively), in blue at 455 nm (phototropic function), and in far-red at 735 nm (important for photomorphology). Morphological characteristics, chlorophyll and phytohormone concentrations in radish and lettuce grown in phytotron chambers under lighting with different spectral composition of the LED-based illuminator and under illumination by high pressure sodium lamps with an equivalent photosynthetic photon flux density were compared. A well-balanced solid-state lighting was found to enhance production of green mass and to ensure healthy morphogenesis of plants compared to those grown using conventional lighting. We observed that the plant morphology and concentrations of morphologically active phytohormones is strongly affected by the spectral composition of light in the red region. Commercial application of the LED-based illumination for large-scale plant cultivation is discussed. This technology is favorable from the point of view of energy consumption, controllable growth, and food safety but is hindered by high cost of the LEDs. Large scale manufacturing of high-power red AlInGaP-based LEDs emitting at 650 nm and a further decrease of the photon price for the LEDs emitting in the vicinity of the absorption peak of chlorophylls have to be achieved to promote horticulture applications.

  11. Optical design of a high-power LED-based solar simulator

    NASA Astrophysics Data System (ADS)

    Toro-Betancur, Veronica; Velásquez-López, Alejandro; Velásquez, David; Acevedo-Gómez, David

    2016-04-01

    The optical design of a High-Power LED based Solar Simulator was made in order to reach the AM1.5G spectrum standards. An optical model of the light emitted by the LEDs was made and used for spectral intensities calculations and the light intensity uniformity was optimized. A class AAA solar simulator was designed using a hexagonal LED distribution.

  12. High intensity hadron accelerators

    SciTech Connect

    Teng, L.C.

    1989-05-01

    This rapporteur report consists mainly of two parts. Part I is an abridged review of the status of all High Intensity Hadron Accelerator projects in the world in semi-tabulated form for quick reference and comparison. Part II is a brief discussion of the salient features of the different technologies involved. The discussion is based mainly on my personal experiences and opinions, tempered, I hope, by the discussions I participated in in the various parallel sessions of the workshop. In addition, appended at the end is my evaluation and expression of the merits of high intensity hadron accelerators as research facilities for nuclear and particle physics.

  13. High performance RGB LED backlight in high temperature environment

    NASA Astrophysics Data System (ADS)

    Grabski, Grzegorz; Gurr, Walter; Green, John

    2008-04-01

    The Aerospace and Defense display industry is in the midst of converting light the sources used in AMLCD backlighting technology from fluorescent lamps to LEDs. Although challenging, the fluorescent backlighting technology delivered good product in high end applications. LEDs, however, have the promise of even greater efficiency and lower cost. The history of LED backlighting is short and very dynamic; expectations are high and promises are many. It appears that for engineers developing backlights for high performance displays life has not become easier with the change of the technology. This paper will discuss just one of many challenges engineer's face: operation of LED backlights in high temperature environments. It will present experimental data showing several advantages of the RGB LED technology over other lamp technologies for high performance commercial and military application.

  14. High Performance Green LEDs by Homoepitaxial

    SciTech Connect

    Wetzel, Christian; Schubert, E Fred

    2009-11-22

    This work's objective was the development of processes to double or triple the light output power from green and deep green (525 - 555 nm) AlGaInN light emitting diode (LED) dies within 3 years in reference to the Lumileds Luxeon II. The project paid particular effort to all aspects of the internal generation efficiency of light. LEDs in this spectral region show the highest potential for significant performance boosts and enable the realization of phosphor-free white LEDs comprised by red-green-blue LED modules. Such modules will perform at and outperform the efficacy target projections for white-light LED systems in the Department of Energy's accelerated roadmap of the SSL initiative.

  15. LED module with high index lens

    DOEpatents

    Bierhuizen, Serge J.; Wang, Nanze Patrick; Eng, Gregory W.; Sun, Decai; Wei, Yajun

    2016-07-05

    An array of housings with housing bodies and lenses is molded, or an array of housing bodies is molded and bonded with lenses to form an array of housings with housing bodies and lenses. Light-emitting diodes (LEDs) are attached to the housings in the array. An array of metal pads may be bonded to the back of the array or insert molded with the housing array to form bond pads on the back of the housings. The array is singulated to form individual LED modules.

  16. LEDs on curved ceramic substrate with primary optics for modification of luminous intensity

    NASA Astrophysics Data System (ADS)

    Wei, An-Chi; Sze, Jyh-Rou; Chern, Jyh-Long

    2011-10-01

    Unlike the conventional LED luminary with a planar substrate and only the forward emission, the proposed LED luminary with a curved ceramic substrate can perform both the forward and the backward emissions. Assembled with the proper primary optics, an illustrated LED bulb has been designed, fabricated and measured. The measured luminous intensity of the LED bulb has shown the backward emission and designed distribution with the beam-angle of 133°. To broaden the application areas, such a LED bulb on a curved substrate has been modularized as a streetlight. The measured results of the proposed streetlight have shown that the beam angle of the luminous intensity and the luminaire efficiency are 132° and 86%, respectively. Meanwhile, its luminous characteristics also fit the standard for lighting design of urban roads.asei.c

  17. High intensity proton synchrotrons

    NASA Astrophysics Data System (ADS)

    Craddock, M. K.

    1986-10-01

    Strong initiatives are being pursued in a number of countries for the construction of ``kaon factory'' synchrotrons capable of producing 100 times more intense proton beams than those available now from machines such as the Brookhaven AGS and CERN PS. Such machines would yield equivalent increases in the fluxes of secondary particles (kaons, pions, muons, antiprotons, hyperons and neutrinos of all varieties)—or cleaner beams for a smaller increase in flux—opening new avenues to various fundamental questions in both particle and nuclear physics. Major areas of investigation would be rare decay modes, CP violation, meson and hadron spectroscopy, antinucleon interactions, neutrino scattering and oscillations, and hypernuclear properties. Experience with the pion factories has already shown how high beam intensities make it possible to explore the ``precision frontier'' with results complementary to those achievable at the ``energy frontier''. This paper will describe proposals for upgrading and AGS and for building kaon factories in Canada, Europe, Japan and the United States, emphasizing the novel aspects of accelerator design required to achieve the desired performance (typically 100 μA at 30 GeV).

  18. Design method for automotive high-beam LED optics

    NASA Astrophysics Data System (ADS)

    Byzov, Egor V.; Moiseev, Mikhail A.; Doskolovich, Leonid L.; Kazanskiy, Nikolay L.

    2015-09-01

    New analytical method for the calculation of the LED secondary optics for automotive high-beam lamps is presented. Automotive headlamps should illuminate the road and the curb at the distance of 100-150 meters and create a bright, flat, relatively powerful light beam. To generate intensity distribution of this kind we propose to use TIR optical element (collimator working on the total internal reflection principle) with array of microlenses (optical corrector) on the upper surface. TIR part of the optical element enables reflection of the side rays to the front direction and provides a collimated beam which incidents on the microrelief. Microrelief, in its turn, dissipates the light flux in horizontal direction to meet the requirements of the Regulations 112, 113 and to provide well-illuminated area across the road in the far field. As an example, we computed and simulated the optical element with the diameter of 33 millimeters and the height of 22 millimeters. Simulation data shows that three illuminating modules including Cree XP-G2 LED and lens allow generating an appropriate intensity distribution for the class D of UNECE Regulations.

  19. Lensless transport-of-intensity phase microscopy and tomography with a color LED matrix

    NASA Astrophysics Data System (ADS)

    Zuo, Chao; Sun, Jiasong; Zhang, Jialin; Hu, Yan; Chen, Qian

    2015-07-01

    We demonstrate lens-less quantitative phase microscopy and diffraction tomography based on a compact on-chip platform, using only a CMOS image sensor and a programmable color LED array. Based on multi-wavelength transport-of- intensity phase retrieval and multi-angle illumination diffraction tomography, this platform offers high quality, depth resolved images with a lateral resolution of ˜3.7μm and an axial resolution of ˜5μm, over wide large imaging FOV of 24mm2. The resolution and FOV can be further improved by using a larger image sensors with small pixels straightforwardly. This compact, low-cost, robust, portable platform with a decent imaging performance may offer a cost-effective tool for telemedicine needs, or for reducing health care costs for point-of-care diagnostics in resource-limited environments.

  20. High power LEDs and the organization of light

    NASA Astrophysics Data System (ADS)

    Paolini, Steve; Harbers, Gerard

    2006-02-01

    High-power Light Emitting Diodes (LEDs) were introduced in the market in 1998 by Lumileds. High-power LEDs have unique properties, very different from conventional light sources, creating never before possible solutions available to lighting designers. In this paper we will give an update on these devices and discuss the main benefits of LEDs compared to more traditional light sources. We will show that the benefits of high-power LEDs also relate to the organization of light they emit. Comparisons of more and less organized light sources as well as applications for highpower LEDs will be discussed.

  1. Advanced packaging methods for high-power LED modules

    NASA Astrophysics Data System (ADS)

    Jordan, Rafael C.; Weber, Constanze; Ehrhardt, Christian; Wilke, Martin

    2014-02-01

    LED luminaires are already beyond retrofit systems, which are limited in heat dissipation due to the old fitting standards. Actual LED luminaries are based on new LED packages and modules. Heat dissipation through the first and second level interconnect is a key issue for a successful LED package. Therefore the impact of known bonding technologies as gluing and soldering and new technologies like sintering and transient liquid phase soldering were analyzed and compared. A realized hermetic high power LED package will be shown as example. The used new techniques result in a module extremely stable against further assembly processes and harsh operating conditions.

  2. High Efficiency Driving Electronics for General Illumination LED Luminaires

    SciTech Connect

    Upadhyay, Anand

    2012-10-31

    New generation of standalone LED driver platforms developed, which are more efficient These LED Drivers are more efficient (≥90%), smaller in size ( 0.15 in3/watt), lower in cost ( 12 cents/watt in high volumes in millions of units). And these products are very reliable having an operating life of over 50,000 hours. This technology will enable growth of LED light sources in the use. This will also help in energy saving and reducing total life cycle cost of LED units. Two topologies selected for next generation of LED drivers: 1) Value engineered single stage Flyback topology. This is suitable for low powered LED drivers up to 50W power. 2) Two stage boost power factor correction (PFC) plus LLC half bridge platform for higher powers. This topology is suitable for 40W to 300W LED drivers. Three new product platforms were developed to cover a wide range of LED drivers: 1) 120V 40W LED driver, 2) Intellivolt 75W LED driver, & 3) Intellivolt 150W LED driver. These are standalone LED drivers for rugged outdoor lighting applications. Based on these platforms number of products are developed and successfully introduced in the market place meeting key performance, size and cost goals.

  3. LED light engine concept with ultra-high scalable luminance

    NASA Astrophysics Data System (ADS)

    Hoelen, Christoph; de Boer, Dick; Bruls, Dominique; van der Eyden, Joost; Koole, Rolf; Li, Yun; Mirsadeghi, Mo; Vanbroekhoven, Vincent; Van den Bergh, John-John; Van de Voorde, Patrick

    2016-03-01

    Although LEDs have been introduced successfully in many general lighting applications during the past decade, high brightness light source applications are still suffering from the limited luminance of LEDs. High power LEDs are generally limited in luminance to ca 100 Mnit (108 lm/m2sr) or less, while dedicated devices for projection may achieve luminance values up to ca 300 Mnit with phosphor converted green. In particular for high luminous flux applications with limited étendue, like in front projection systems, only very modest luminous flux values in the beam can be achieved with LEDs compared to systems based on discharge lamps. In this paper we introduce a light engine concept based on a light converter rod pumped with blue LEDs that breaks through the étendue and brightness limits of LEDs, enabling LED light source luminance values that are more than 4 times higher than what can be achieved with LEDs so far. In LED front projection systems, green LEDs are the main limiting factor. With our green light emitting modules, peak luminance values well above 1.2 Gnit have been achieved, enabling doubling of the screen brightness of LED based DLP projection systems, and even more when this technology is applied to other colors as well. This light source concept, introduced as the ColorSpark High Lumen Density (HLD) LED technology, enables a breakthrough in the performance of LED-based light engines not only for projection, where >2700 ANSI lm was demonstrated, but for a wide variety of high brightness applications.

  4. HIGH LIFE: High altitude fatalities led to pulse oximetry.

    PubMed

    Severinghaus, John W

    2016-01-15

    In 1875, Paul Bert linked high altitude danger to the low partial pressure of oxygen when 2 of 3 French balloonists died euphorically at about 8,600 m altitude. World War I fatal crashes of high altitude fighter pilots led to a century of efforts to use oximetry to warn pilots. The carotid body, discovered in 1932 to be the hypoxia detector, led to most current physiologic understanding of the body's respiratory responses to hypoxia and CO2. The author describes some of his UCSF group's work: In 1963, we reported both the brain's ventral medullary near-surface CO2 (and pH) chemosensors and the role of cerebrospinal fluid in acclimatization to altitude. In 1966, we reported the effect of altitude on cerebral blood flow and later the changes of carotid body sensitivity at altitude and the differences in natives of high altitude. In 1973, pulse oximetry was invented when Japanese biophysicist Takuo Aoyagi read and applied to pulses a largely forgotten 35-year-old discovery by English medical student J. R. Squire of a method of computing oxygen saturation from red and infrared light passing through both perfused and blanched tissue. PMID:26251514

  5. High-Modulation-Speed LEDs Based on III-Nitride

    NASA Astrophysics Data System (ADS)

    Chen, Hong

    III-nitride InGaN light-emitting diodes (LEDs) enable wide range of applications in solid-state lighting, full-color displays, and high-speed visible-light communication. Conventional InGaN quantum well LEDs grown on polar c-plane substrate suffer from quantum confined Stark effect due to the large internal polarization-related fields, leading to a reduced radiative recombination rate and device efficiency, which limits the performance of InGaN LEDs in high-speed communication applications. To circumvent these negative effects, non-trivial-cavity designs such as flip-chip LEDs, metallic grating coated LEDs are proposed. This oral defense will show the works on the high-modulation-speed LEDs from basic ideas to applications. Fundamental principles such as rate equations for LEDs/laser diodes (LDs), plasmonic effects, Purcell effects will be briefly introduced. For applications, the modal properties of flip-chip LEDs are solved by implementing finite difference method in order to study the modulation response. The emission properties of highly polarized InGaN LEDs coated by metallic gratings are also investigated by finite difference time domain method.

  6. High-luminance LEDs replace incandescent lamps in new applications

    NASA Astrophysics Data System (ADS)

    Evans, David L.

    1997-04-01

    The advent of high luminance AlInGaP and InGaN LED technologies has prompted the use of LED devices in new applications formally illuminated by incandescent lamps. The luminous efficiencies of these new LED technologies equals or exceeds that attainable with incandescent sources, with reliability factors that far exceed those of incandescent sources. The need for a highly efficient, dependable, and cost effective replacement for incandescent lamps is being fulfilled with high luminance LED lamps. This paper briefly described some of the new applications incorporating high luminance LED lamps, traffic signals and roadway signs for traffic management, automotive exterior lighting, active matrix and full color displays for commercial advertising, and commercial aircraft panel lighting and military aircraft NVG compatible lighting.

  7. Acute LED irradiation does not change the anaerobic capacity and time to exhaustion during a high-intensity running effort: a double-blind, crossover, and placebo-controlled study : Effects of LED irradiation on anaerobic capacity and performance in running.

    PubMed

    Malta, Elvis De Souza; De Poli, Rodrigo Araujo Bonetti; Brisola, Gabriel Motta Pinheiro; Milioni, Fabio; Miyagi, Willian Eiji; Machado, Fabiana Andrade; Zagatto, Alessandro Moura

    2016-09-01

    The purpose of this study was to investigate the acute effects of photobiomodulation therapy using cluster light-emitting diodes (LEDT; 104 diodes) (wavelength 660 and 850 nm; energy density 1.5 and 4.5 J/cm(2); energy 60 J at each point; total energy delivered 600 J) on alternative maximal accumulated oxygen deficit (MAODALT) and time to exhaustion, during a high-intensity running effort. Fifteen moderately active and healthy males (age 25.1 ± 4.4 years) underwent a graded exercise test and two supramaximal exhaustive efforts at 115 % of the intensity associated with maximal oxygen uptake performed after acute LEDT or placebo irradiation in a double-blind, crossover, and placebo-controlled study design. The MAODALT was assumed as the sum of both oxygen equivalents estimated from the glycolytic and phosphagen metabolism pathways during each supramaximal effort. For the statistical analysis, a paired t test was used to determine differences between the treatments. The significance level was assumed as 95 %. In addition, a qualitative analysis was used to determine the magnitude of differences between groups. No significant differences were found for the values of oxygen equivalents from each energetic metabolism (P ≥ 0.28), for MAODALT values between the LEDT and placebo conditions (P ≥ 0.27), or for time to exhaustion (P = 0.80), except for the respiratory exchange ratio (P = 0.01). The magnitude-based inference of effect size reported only a possibly negative effect of photobiomodulation on MAODALT when expressed in units relative to body mass and on the glycolysis pathway (26 %). In summary, LEDT after a high-intensity running effort did not alter the MAODALT, metabolic energy pathways, or high-intensity running performance. PMID:27384042

  8. Comparative study of laser and LED systems of low intensity applied to tendon healing

    NASA Astrophysics Data System (ADS)

    Bastos, J. L. N.; Lizarelli, R. F. Z.; Parizotto, N. A.

    2009-09-01

    The aim of this study was to compare the effects of Low-intensity Laser Therapy (LILT) and Light Emitting Diode Therapy (LEDT) of low intensity on the treatment of lesioned Achilles tendon of rats. The experimental model consisted of a partial mechanical lesion on the right Achilles tendon deep portion of 90 rats. One hour after the lesion, the injured animals received applications of laser/LED (685, 830/630, 880 nm), and the same procedure was repeated at 24-h intervals, for 10 days. The healing process and deposition of collagen were evaluated based on a polarization microscopy analysis of the alignment and organization of collagen bundles, through the birefringence (optical retardation-OR). The results showed a real efficiency of treatments based on LEDT and confirmed that LILT seems to be effective on healing process. Although absence of coherence of LED light, tendon healing treatment with this feature was satisfactory and can certainly replace treatments based on laser light applications. Applications of infrared laser at 830 nm and LED 880 nm were more efficient when the aim is a good organization, aggregation, and alignment of the collagen bundles on tendon healing. However, more research is needed for a safety and more efficient determination of a protocol with LED.

  9. Low Cost Lithography Tool for High Brightness LED Manufacturing

    SciTech Connect

    Andrew Hawryluk; Emily True

    2012-06-30

    The objective of this activity was to address the need for improved manufacturing tools for LEDs. Improvements include lower cost (both capital equipment cost reductions and cost-ofownership reductions), better automation and better yields. To meet the DOE objective of $1- 2/kilolumen, it will be necessary to develop these highly automated manufacturing tools. Lithography is used extensively in the fabrication of high-brightness LEDs, but the tools used to date are not scalable to high-volume manufacturing. This activity addressed the LED lithography process. During R&D and low volume manufacturing, most LED companies use contact-printers. However, several industries have shown that these printers are incompatible with high volume manufacturing and the LED industry needs to evolve to projection steppers. The need for projection lithography tools for LED manufacturing is identified in the Solid State Lighting Manufacturing Roadmap Draft, June 2009. The Roadmap states that Projection tools are needed by 2011. This work will modify a stepper, originally designed for semiconductor manufacturing, for use in LED manufacturing. This work addresses improvements to yield, material handling, automation and throughput for LED manufacturing while reducing the capital equipment cost.

  10. Primary optics for efficient high-brightness LED colour mixing

    NASA Astrophysics Data System (ADS)

    Cvetkovic, A.; Mohedano, R.; Dross, O.; Hernandez, M.; Benítez, P.; Miñano, J. C.; Vilaplana, J.; Chaves, J.

    2012-10-01

    In SSL general illumination, there is a clear trend to high flux packages with higher efficiency and higher CRI addressed with the use of multiple color chips and phosphors. However, such light sources require the optics provide color mixing, both in the near-field and far-field. This design problem is specially challenging for collimated luminaries, in which diffusers (which dramatically reduce the brightness) cannot be applied without enlarging the exit aperture too much. In this work we present first injection molded prototypes of a novel primary shell-shaped optics that have microlenses on both sides to provide Köhler integration. This shell is design so when it is placed on top of an inhomogeneous multichip Lambertian LED, creates a highly homogeneous virtual source (i.e, spatially and angularly mixed), also Lambertian, which is located in the same position with only small increment of the size (about 10-20%, so the average brightness is similar to the brightness of the source). This shell-mixer device is very versatile and permits now to use a lens or a reflector secondary optics to collimate the light as desired, without color separation effects. Experimental measurements have shown optical efficiency of the shell of 95%, and highly homogeneous angular intensity distribution of collimated beams, in good agreement with the ray-tracing simulations.

  11. High Intensity Lights

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Xenon arc lamps developed during the Apollo program by Streamlight, Inc. are the basis for commercial flashlights and emergency handlights. These are some of the brightest portable lights made. They throw a light some 50 times brighter than automobile high beams and are primarily used by police and military. The light penetrates fog and smoke and returns less back-scatter light. They are operated on portable power packs as boat and auto batteries. An infrared model produces totally invisible light for covert surveillance.

  12. LED white lights with high CRI and high luminous efficacy

    NASA Astrophysics Data System (ADS)

    He, Guoxing; Zheng, Lihong; Yan, Huafeng

    2010-11-01

    The models for spectra of a phosphor-coated white (p-W) LED and a white light LED cluster are developed based on the principle of additive color mixture. The simulation results show that p-W LEDs consisting of a blue chip (450nm), green phosphor (507 nm), yellow phosphor (580 nm) and red phosphor (655 nm) could realize color rendering indices (CRIs) above 97.7 and special CRIs of R1 to R14 above 91.1, but luminous efficacies of radiation (LERs) below 250.3 lm/W, that white/red clusters consisting of red LEDs and p-W LEDs with a blue chip (450nm), green (507 nm) and yellow (580 nm) phosphors could realize given color temperature white light with CRIs above 97.9 and special CRIs of R1 to R14 above 89.6, as well as LERs above 296.3 lm/W, and that a neutral-white /red//blue cluster consisting of blue LEDs (465 nm), red LEDs (628 nm) and neutral-white LEDs with a blue chip (452 nm), green (530 nm) and yellow (586 nm) phosphors could realize CCT tunable white lights with CRIs above 97.9 and special CRIs of R1 to R14 above 89.6, as well as LER above 296.3 lm/W.

  13. Effect of blue LED light intensity on carotenoid accumulation in citrus juice sacs.

    PubMed

    Zhang, Lancui; Ma, Gang; Yamawaki, Kazuki; Ikoma, Yoshinori; Matsumoto, Hikaru; Yoshioka, Terutaka; Ohta, Satoshi; Kato, Masaya

    2015-09-01

    In the present study, the effects of blue LED light intensity on carotenoid accumulation and expression of genes related to carotenoid biosynthesis were investigated in the juice sacs of Satsuma mandarin (Citrus unshiu Marc.) and Valencia orange (Citrus sinensis Osbeck) in vitro. The results showed that 100 μmol m(-2)s(-1) blue LED light (100B) was effective for increasing carotenoid content, especially β-cryptoxanthin, in Satsuma mandarin after cultured in vitro for four weeks. In Valencia orange, in contrast, 50 μmol m(-2)s(-1) blue LED light (50B) treatment was effective for inducing carotenoid accumulation through increasing the contents of two major carotenoids, all-trans-violaxanthin and 9-cis-violaxanthin. In addition, gene expression results showed that the simultaneous increases in the expression of genes (CitPSY, CitPDS, CitZDS, CitLCYb2, and CitHYb) involved in producing β,β-xanthophylls were well consistent with the accumulation of β-cryptoxanthin in Satsuma mandarin under 100B, and violaxanthin in Valencia orange under 50B. The results presented herein contribute to further elucidating the regulatory mechanism of carotenoid accumulation by blue LED light. PMID:26432407

  14. Current State of the Art in High Brightness LEDs

    NASA Astrophysics Data System (ADS)

    Craford, George

    2007-03-01

    LED's have been commercially available since the 1960's. For many years they were used primarily for indicator applications. The remarkable increase in materials technology and efficiency that has been achieved since the early 1990's for AlInGaP red and amber LEDs, and InGaN green and blue LEDs, has enabled the penetration of markets such as outdoor display, signaling, and automotive brake light and turn signal applications. White LEDs, which are either blue LEDs combined with a phosphor, or a combination of red, green, and blue LEDs, are being used in emerging applications such as cell phone flash, television backlights, projection, and automotive headlights. In addition, to efficiency improvements these applications have required the development of higher power packages and, in some of these applications which are etendue limited, higher luminance devices. High power devices are commercially available which are capable of 140 lumens output and have an efficacy of around 70 lm/W for white emission. New package and chip technologies have been demonstrated which have a luminance of 38 mega nits (Mcd/m^2), approximately 50% more luminance than that of an automotive headlamp halogen bulb (˜25 mega nits). The recent progress in materials technology, packaging, and chip technology makes it clear that LED's will become important for general illumination applications. The rate of LED penetration of this market will depend upon continued increases in performance and lower costs as well as better control of the white spectral emission. Efficiency, current density, and costs are closely linked because the cost in dollars/lumen is inversely proportional to how many lumens can be realized from each unit of device area for a given device type. Performance as high as 138 lm/W, and over 40% wall plug efficiency, has been reported for low power research devices and over 90 lm/W for high power research devices. It is clear that high power commercial products with performance in

  15. A thermosyphon heat pipe cooler for high power LEDs cooling

    NASA Astrophysics Data System (ADS)

    Li, Ji; Tian, Wenkai; Lv, Lucang

    2016-08-01

    Light emitting diode (LED) cooling is facing the challenge of high heat flux more seriously with the increase of input power and diode density. The proposed unique thermosyphon heat pipe heat sink is particularly suitable for cooling of high power density LED chips and other electronics, which has a heat dissipation potential of up to 280 W within an area of 20 mm × 22 mm (>60 W/cm2) under natural air convection. Meanwhile, a thorough visualization investigation was carried out to explore the two phase flow characteristics in the proposed thermosyphon heat pipe. Implementing this novel thermosyphon heat pipe heat sink in the cooling of a commercial 100 W LED integrated chip, a very low apparent thermal resistance of 0.34 K/W was obtained under natural air convection with the aid of the enhanced boiling heat transfer at the evaporation side and the enhanced natural air convection at the condensation side.

  16. Harmonic generation at high intensities

    SciTech Connect

    Schafer, K.J.; Krause, J.L.; Kulander, K.C.

    1993-06-01

    Atomic electrons subject to intense laser fields can absorb many photons, leading either to multiphoton ionization or the emission of a single, energetic photon which can be a high multiple of the laser frequency. The latter process, high-order harmonic generation, has been observed experimentally using a range of laser wavelengths and intensities over the past several years. Harmonic generation spectra have a generic form: a steep decline for the low order harmonics, followed by a plateau extending to high harmonic order, and finally an abrupt cutoff beyond which no harmonics are discernible. During the plateau the harmonic production is a very weak function of the process order. Harmonic generation is a promising source of coherent, tunable radiation in the XUV to soft X-ray range which could have a variety of scientific and possibly technological applications. Its conversion from an interesting multiphoton phenomenon to a useful laboratory radiation source requires a complete understanding of both its microscopic and macroscopic aspects. We present some recent results on the response of single atoms at intensities relevant to the short pulse experiments. The calculations employ time-dependent methods, which we briefly review in the next section. Following that we discuss the behavior of the harmonics as a function of laser intensity. Two features are notable: the slow scaling of the harmonic intensities with laser intensity, and the rapid variation in the phase of the individual harmonics with respect to harmonic order. We then give a simple empirical formula that predicts the extent of the plateau for a given ionization potential, wavelength and intensity.

  17. Visible LED alternatives for high-radiance applications

    NASA Astrophysics Data System (ADS)

    Altendorf, Eric H.

    2003-07-01

    Laser diodes are used in high radiance applications, requiring spatially and angularly localized optical power, in order to minimize system size, cost, and power requirements. For applications requiring visible wavelengths (400nm to 700nm), AlInGaP laser diodes are utilized for wavelengths between 630nm and 650nm, and recently InGaN-based laser diodes spanning the violet to blue spectral range (400nm to 450nm) have become available, with longer wavelength devices being actively developed. It is not clear, however, when reliable laser diodes emitting in the green to yellow portion of the visible spectrum (>500nm) will be realized. In addition, single mode laser diodes required for high radiance applications typically exhibit speckle effects, are temperature sensitive, require non-linear drive electronics, and can be effected by optical feedback. High radiance LEDs with appropriate emitter dimensions can be used in place of laser diodes provided that moderate coherence and power levels are acceptable. This article examines the general dependencies of beam focusing, collimation, and coherence, on LED emitter size and radiance. Specific model examples are considered, using parameters consistent with typical laser diode collimating lenses. Edge emitting LEDs or EELEDs used for miniature scanned displays are described as high radiance LEDs suitable for other applications requiring collimation, partial coherence, or localized irradiance.

  18. Highly Efficient Small Form Factor LED Retrofit Lamp

    SciTech Connect

    Steven Allen; Fred Palmer; Ming Li

    2011-09-11

    This report summarizes work to develop a high efficiency LED-based MR16 lamp downlight at OSRAM SYLVANIA under US Department of Energy contract DE-EE0000611. A new multichip LED package, electronic driver, and reflector optic were developed for these lamps. At steady-state, the lamp luminous flux was 409 lumens (lm), luminous efficacy of 87 lumens per watt (LPW), CRI (Ra) of 87, and R9 of 85 at a correlated color temperature (CCT) of 3285K. The LED alone achieved 120 lumens per watt efficacy and 600 lumen flux output at 25 C. The driver had 90% electrical conversion efficiency while maintaining excellent power quality with power factor >0.90 at a power of only 5 watts. Compared to similar existing MR16 lamps using LED sources, these lamps had much higher efficacy and color quality. The objective of this work was to demonstrate a LED-based MR16 retrofit lamp for replacement of 35W halogen MR16 lamps having (1) luminous flux of 500 lumens, (2) luminous efficacy of 100 lumens per watt, (3) beam angle less than 40{sup o} and center beam candlepower of at least 1000 candelas, and (4) excellent color quality.

  19. Intensity of blue LED light: a potential stimulus for biomass and lipid content in fresh water microalgae Chlorella vulgaris.

    PubMed

    Atta, Madiha; Idris, Ani; Bukhari, Ataullah; Wahidin, Suzana

    2013-11-01

    Light quality and the intensity are key factors which render microalgae as a potential source of biodiesel. In this study the effects of various intensities of blue light and its photoperiods on the growth and lipid content of Chlorella vulgaris were investigated by using LED (Light Emitting Diode) in batch culture. C. vulgaris was grown for 13 days at three different light intensities (100, 200 and 300 μmol m(-2)s(-1)). Effect of three different light and dark regimes (12:12, 16:08 and 24:00 h Light:Dark) were investigated for each light intensity at 25°C culture temperature. Maximum lipid content (23.5%) was obtained due to high efficiency and deep penetration of 200 μmol m(-2)s(-1) of blue light (12:12 L:D) with improved specific growth (1.26 d(-1)) within reduced cultivation time of 8 days. White light could produce 20.9% lipid content in 10 days at 16:08 h L:D. PMID:24063820

  20. Etendue-preserving mixing and projection optics for high-luminance LEDs, applied to automotive headlamps.

    PubMed

    Cvetkovic, Aleksandra; Dross, Oliver; Chaves, Julio; Benitez, Pablo; Miñano, Juan C; Mohedano, Rubén

    2006-12-25

    By having a single optical element combine the light of several high luminance LEDs, a high luminance light source can be formed, with shape and emission characteristics adaptable to nearly all illumination problems. The illuminance distribution of this virtual source facilitates the generation of the desired intensity pattern via its imaging-stye projection into the far field. This projection is achieved by one refractive and one reflective freeform surface, both calculated simultaneously by the 3D SMS method, which is herein demonstrated for an LED automotive headlamp. PMID:19532196

  1. Digital controlling system to the set of high power LEDs

    NASA Astrophysics Data System (ADS)

    Gilewski, Marian; Gryko, Lukasz; Zajac, Andrzej

    2013-07-01

    In the paper is described the concept and architecture of the multi-channel control system for set of high-power LEDs. The broadband source of radiation for prototype illuminator is dedicated to the investigation of Low Level Laser Therapy procedures. The general scheme of the system, detailed schemes, control algorithm and its implementation description in FPGA structure is presented. The temperature conditions and the opportunity to work with a microcomputer are characterized.

  2. Monolayer graphene dispersion and radiative cooling for high power LED

    NASA Astrophysics Data System (ADS)

    Hsiao, Tun-Jen; Eyassu, Tsehaye; Henderson, Kimberly; Kim, Taesam; Lin, Chhiu-Tsu

    2013-10-01

    Molecular fan, a radiative cooling by thin film, has been developed and its application for compact electronic devices has been evaluated. The enhanced surface emissivity and heat dissipation efficiency of the molecular fan coating are shown to correlate with the quantization of lattice modes in active nanomaterials. The highly quantized G and 2D bands in graphene are achieved by our dispersion technique, and then incorporated in an organic-inorganic acrylate emulsion to form a coating assembly on heat sinks (for LED and CPU). This water-based dielectric layer coating has been formulated and applied on metal core printed circuit boards. The heat dissipation efficiency and breakdown voltage are evaluated by a temperature-monitoring system and a high-voltage breakdown tester. The molecular fan coating on heat dissipation units is able to decrease the equilibrium junction temperature by 29.1 ° C, while functioning as a dielectric layer with a high breakdown voltage (>5 kV). The heat dissipation performance of the molecular fan coating applied on LED devices shows that the coated 50 W LED gives an enhanced cooling of 20% at constant light brightness. The schematics of monolayer graphene dispersion, undispersed graphene platelet, and continuous graphene sheet are illustrated and discussed to explain the mechanisms of radiative cooling, radiative/non-radiative, and non-radiative heat re-accumulation.

  3. High-power UV-B LEDs with long lifetime

    NASA Astrophysics Data System (ADS)

    Rass, Jens; Kolbe, Tim; Lobo-Ploch, Neysha; Wernicke, Tim; Mehnke, Frank; Kuhn, Christian; Enslin, Johannes; Guttmann, Martin; Reich, Christoph; Mogilatenko, Anna; Glaab, Johannes; Stoelmacker, Christoph; Lapeyrade, Mickael; Einfeldt, Sven; Weyers, Markus; Kneissl, Michael

    2015-03-01

    UV light emitters in the UV-B spectral range between 280 nm and 320 nm are of great interest for applications such as phototherapy, gas sensing, plant growth lighting, and UV curing. In this paper we present high power UV-B LEDs grown by MOVPE on sapphire substrates. By optimizing the heterostructure design, growth parameters and processing technologies, significant progress was achieved with respect to internal efficiency, injection efficiency and light extraction. LED chips emitting at 310 nm with maximum output powers of up to 18 mW have been realized. Lifetime measurements show approximately 20% decrease in emission power after 1,000 operating hours at 100 mA and 5 mW output power and less than 30% after 3,500 hours of operation, thus indicating an L50 lifetime beyond 10,000 hours.

  4. Design of blue LEDs array with high optical power

    NASA Astrophysics Data System (ADS)

    Lu, Pengzhi; Yang, Hua; Xue, Bin; Xie, Haizhong; Li, Jing; Yi, Xiaoyan; Wang, Junxi; Wang, Guohong; Li, Jinmin

    2014-11-01

    In this paper, an array of blue LEDs with high optical power was presented and discussed. Optical of the novel design was completed with the help of running simulation in TracePro to predict the performance of the module. 36 Cree XP-E blue LEDs with a square reflector were used in the novel design. Optical simulation obtained from TracePro showed that the total optical power of the LED array could reach 16.83W. To verify the simulation results, Aluminum PCB, Copper PCB and Aluminum square reflector have been made respectively. Firstly, 36 Cree XP-E blue LEDs with small-pitch were fixed on each PCB, then; an Aluminum square reflector was assembled on each PCB. This optical module was installed on a radiator and tested. The optical output power of sample 1 used Aluminum PCB and Aluminum reflector and sample 2 used Copper PCB and Aluminum reflector was 8.126W and 9.445W at 2A, respectively. It could be observed that the optical output power of sample 2 was higher than that of sample 1. It could be attributed to the better thermal dispersion performance of Copper. In order to improve the light reflectivity and reduce the loss of light, ultrathin silver was coated on the Aluminum reflector by electron beam evaporation. The optical output power of sample 3 used Copper PCB and silver-plated Aluminum reflector was 12.541W at 2A. A uniform square spot with high optical power was obtained.

  5. High Intensity Polarized Electron Gun

    SciTech Connect

    Redwine, Robert P.

    2012-07-31

    The goal of the project was to investigate the possibility of building a very high intensity polarized electron gun for the Electron-Ion Collider. This development is crucial for the eRHIC project. The gun implements a large area cathode, ring-shaped laser beam and active cathode cooling. A polarized electron gun chamber with a large area cathode and active cathode cooling has been built and tested. A preparation chamber for cathode activation has been built and initial tests have been performed. Major parts for a load-lock chamber, where cathodes are loaded into the vacuum system, have been manufactured.

  6. Intensity of an oxygen saturation image improved using scanning NIR-LED light irradiation

    NASA Astrophysics Data System (ADS)

    Tsai, Hsin-Yi; Yang, Ching-Ching; Hung, Min-Wei; Huang, Kuo-Cheng

    2014-09-01

    A near-infrared (940 nm) image of skin tissue can be substantially enhanced using optical scanning technology (OST) that can reduce the scattering effect and remove the wrinkles or fine hair in the image. Using OST to create the skin tissue image ensured that the contour of blood vessels became more clear than that obtained from the divergent light source. In addition, the oxygen saturation of the blood vessels and tissues obtained using OST were approximately 98.65 and 93.17%, respectively, exhibiting an increase of more than 20% compared with that obtained using divergent light, and approached the value when measured using commercial pulse oximetry. Because the proposed method has a deep light penetration depth and high image intensity and resolution for oxygen saturation analysis, it is highly appropriate to be applied to future studies on diabetes and cardiovascular diseases.

  7. Diagnostics of High-Intensity-Discharges

    NASA Astrophysics Data System (ADS)

    Adler, Helmar G.

    1996-05-01

    High intensity light sources have come a long way since the introduction of high pressure discharges in mercury and later in sodium. The introduction of other species (e.g. metal halides) into the discharge chemistry led to marked improvements in light intensity (lumens per watt or LPW) and the appearance of the light output (color rendering index or CRI). Many of these improvements have been achieved through qualitative understanding of the discharge and good engineering. The accurate predictions of discharge behavior and spectral power distribution through HID-models remains a difficult and challenging goal for lighting scientists. Modelling of a real lamp is complicated due to the high pressures in the discharge, the geometric influences of the discharge vessel, and the interactions between fills, wall materials and electrodes. The simultaneous use of solid-, liquid-, gaseous- and plasma-state descriptions, including for example effects of radiation transport, becomes necessary. Spectroscopic measurements have been and are still of highest value, not only to determine practical parameters like LPW and CRI, but also to determine species distributions and temperatures, eventually as a function of location in the discharge and time. These measurements are necessary not only for the quantitative understanding of the discharge mechanisms, but also to serve as a testbed for all simulation efforts. This paper will focus on diagnostic possibilities and opportunities using imaging data acquisition systems.

  8. Color uniformity and data simulation in high-power RGB LED modules using different LED-chips arrays

    NASA Astrophysics Data System (ADS)

    Tu, Yan; Jin, Shangzhong; Wang, Yanhua; Dou, Liangliang

    2007-11-01

    The continuing research efforts in white light created by mixing red, green and blue light emitting diodes (RGB LED) will allow their applications in high quality lighting systems in the (near) future. There are still many issues to tackle in this kind of light source, for instance the color uniformity and the change of color-render property owing to the change of LED's temperature. In this paper we simulate the effects on color uniformity of the near-field light distribution due to different LED-chips arrays (at optimum packaging density for uniform irradiance) using High-Power RGB LED-chips. The results showing the color uniformity of near-field which can be achieved with different RGB LED-chips arrays are presented. Several configurations of RGB LED-chips arrays and relevant data for color variation are given respectively. An analysis of luminous efficacy of radiation (LER) and color rendering index (CRI) of this source is performed, which are affected by the peak wavelength, spectral width, and the output peak emission power ratio of LED-chips.

  9. High intensity portable fluorescent light

    NASA Technical Reports Server (NTRS)

    Kendall, F. B.

    1972-01-01

    Eight high intensity portable fluorescent lights were produced. Three prototype lights were also produced, two of which were subsequently updated to the physical and operational configuration of the qualification and flight units. Positioning of lamp apertures and reflectors in these lights is such that the light is concentrated and intensified in a specific pattern rather than widely diffused. Indium amalgam control of mercury vapor pressure in the lamp gives high output at lamp ambient temperatures up to 105 C. A small amount of amalgam applied to each electrode stem helps to obtain fast warm-up. Shrinking a Teflon sleeve on the tube and potting metal caps on each end of the lamp minimizes dispersion of mercury vapor and glass particles in the event of accidental lamp breakage. Operation at 20 kHz allows the lamps to consume more power than at low frequency, thus increasing their light output and raising their efficiency. When used to expose color photographic film, light from the lamps produces results approximately equal to sunlight.

  10. High performance, LED powered, waveguide based total internal reflection microscopy

    NASA Astrophysics Data System (ADS)

    Ramachandran, Srinivasan; Cohen, Daniel A.; Quist, Arjan P.; Lal, Ratnesh

    2013-07-01

    Total internal reflection fluorescence (TIRF) microscopy is a rapidly expanding optical technique with excellent surface sensitivity and limited background fluorescence. Commercially available TIRF systems are either objective based that employ expensive special high numerical aperture (NA) objectives or prism based that restrict integrating other modalities of investigation for structure-function analysis. Both techniques result in uneven illumination of the field of view and require training and experience in optics. Here we describe a novel, inexpensive, LED powered, waveguide based TIRF system that could be used as an add-on module to any standard fluorescence microscope even with low NA objectives. This system requires no alignment, illuminates the entire field evenly, and allows switching between epifluorescence/TIRF/bright field modes without adjustments or objective replacements. The simple design allows integration with other imaging systems, including atomic force microscopy (AFM), for probing complex biological systems at their native nanoscale regimes.

  11. Highly sensitive Fourier transform spectroscopy with LED sources

    NASA Astrophysics Data System (ADS)

    Serdyukov, V. I.; Sinitsa, L. N.; Vasil'chenko, S. S.

    2013-08-01

    It is shown that the use of high luminance LED emitters as a light source for Fourier transform spectrometers permits to enhance their threshold sensitivity in the visible range by orders of magnitude. Using a 2.5 W Edixeon EDEI-1LS3 emitter in the range of 11,350-11,700 cm-1 as a light source for the spectrometer with a 60-cm multipass cell during a 24-h measurement time, we have achieved a signal-to-noise ratio of 4.5 × 104 which corresponds to the minimal detectable absorption coefficient of 1.2 × 10-8 cm-1. Such enhanced sensitivity spectrometer has been used to measure the transition frequencies of CO2 vibrational bands 00051-00001 and 01151-01101 in the range of 11,400-11,500 cm-1.

  12. High Intensity Accelerator and Neutron Source in China

    SciTech Connect

    Guan Xialing; Wei, J.; Loong Chun

    2011-06-28

    High intensity Accelerator is being studied all over world for numerous applications, which includes the waste transmutation, spallation neutron source and material irradiation facilities. The R/D activities of the technology of High intensity accelerator are also developed in China for some year, and have some good facilities around China. This paper will reports the status of some high intensity accelerators and neutron source in China, which including ADS/RFQ; CARR; CSNS; PKUNIFTY and CPHS. This paper will emphatically report the Compact Pulsed Hadron Source (CPHS) led by the Department of Engineering Physics of Tsinghua University in Beijing, China.

  13. High intensity protons in RHIC

    SciTech Connect

    Montag, C.; Ahrens, L.; Blaskiewicz, M.; Brennan, J. M.; Drees, K. A.; Fischer, W.; Huang, H.; Minty, M.; Robert-Demolaize, G.; Thieberger, P.; Yip, K.

    2012-01-05

    During the 2012 summer shutdown a pair of electron lenses will be installed in RHIC, allowing the beam-beam parameter to be increased by roughly 50 percent. To realize the corresponding luminosity increase bunch intensities have to be increased by 50 percent, to 2.5 {center_dot} 10{sup 11} protons per bunch. We list the various RHIC subsystems that are most affected by this increase, and propose beam studies to ensure their readiness. The proton luminosity in RHIC is presently limited by the beam-beam effect. To overcome this limitation, electron lenses will be installed in IR10. With the help of these devices, the headon beam-beam kick experienced during proton-proton collisions will be partially compensated, allowing for a larger beam-beam tuneshift at these collision points, and therefore increasing the luminosity. This will be accomplished by increasing the proton bunch intensity from the presently achieved 1.65 {center_dot} 10{sup 11} protons per bunch in 109 bunches per beam to 2.5 {center_dot} 10{sup 11}, thus roughly doubling the luminosity. In a further upgrade we aim for bunch intensities up to 3 {center_dot} 10{sup 11} protons per bunch. With RHIC originally being designed for a bunch intensity of 1 {center_dot} 10{sup 11} protons per bunch in 56 bunches, this six-fold increase in the total beam intensity by far exceeds the design parameters of the machine, and therefore potentially of its subsystems. In this note, we present a list of major subsystems that are of potential concern regarding this intensity upgrade, show their demonstrated performance at present intensities, and propose measures and beam experiments to study their readiness for the projected future intensities.

  14. Reliability test and failure analysis of high power LED packages

    NASA Astrophysics Data System (ADS)

    Zhaohui, Chen; Qin, Zhang; Kai, Wang; Xiaobing, Luo; Sheng, Liu

    2011-01-01

    A new type application specific light emitting diode (LED) package (ASLP) with freeform polycarbonate lens for street lighting is developed, whose manufacturing processes are compatible with a typical LED packaging process. The reliability test methods and failure criterions from different vendors are reviewed and compared. It is found that test methods and failure criterions are quite different. The rapid reliability assessment standards are urgently needed for the LED industry. 85 °C/85 RH with 700 mA is used to test our LED modules with three other vendors for 1000 h, showing no visible degradation in optical performance for our modules, with two other vendors showing significant degradation. Some failure analysis methods such as C-SAM, Nano X-ray CT and optical microscope are used for LED packages. Some failure mechanisms such as delaminations and cracks are detected in the LED packages after the accelerated reliability testing. The finite element simulation method is helpful for the failure analysis and design of the reliability of the LED packaging. One example is used to show one currently used module in industry is vulnerable and may not easily pass the harsh thermal cycle testing.

  15. High-efficiency trichromatic LED backlight for mobile LCDs

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Ha; Park, Moo Youn; Kim, Jin-Jong; Kim, Heedong; Jun, Joo-Hee; Park, Jae-Hyuk; Cho, Sung-Min; Lee, Dong-Woo; Hwang, Soo Ryong; Jeong, Ho-Seop

    2006-02-01

    Trichromatic LED backlights render higher color gamut and panel transmittance to the liquid crystal displays (LCDs) than yellow phosphor-converted white LED backlights can possibly do at their best. In realization, however, several technical challenges arise, such as color mixing, minimizing the total number of chips, and maintaining the color balance. We designed and demonstrated a backlight unit for 2.2 inch TFT LCD using two RGB 3-chip LEDs to assess the feasibility and the technical hurdles to overcome. The average brightness of the backlight is 2509cd/m2 at the input power of 200mW. The power efficiency is lower than but comparable to commercially available white LED backlights. The color gamut of the LC panel is increased from 53% to 78% when its conventional white LED backlight is replaced by the trichromatic LED backlight. Panel transmittance is expected to be enhanced as well by about 8%. The ambient temperature change was found to be the most significant cause of the color shift of the trichromatic LED backlight. The forward bias voltage can be used in the feedback, since it changes linearly with temperature.

  16. Evaluation of a Peer-Led, Low-Intensity Physical Activity Program for Older Adults

    ERIC Educational Resources Information Center

    Werner, Danilea; Teufel, James; Brown, Stephen L.

    2014-01-01

    Background: Physical inactivity is a primary contributor to decreasing functional physical fitness and increasing chronic disease in older adults. Purpose: This study assessed the health-related benefits of ExerStart for Lay Leaders, a 20-week, community based, peer-led, low-impact exercise program for older adults. ExerStart focuses on aerobic…

  17. High CRI phosphor blends for near-UV LED lamps

    NASA Astrophysics Data System (ADS)

    Radkov, Emil; Setlur, Anant; Brown, Zena; Reginelli, James

    2004-10-01

    Currently, the highest color rendering index (CRI) value obtained in commercially available LED devices is around 90. This falls short of the CRI values typical for incandescent lamps (defined at 100). Similarly, the commercially available LEDs for higher color temperature have CRI values of 65-85, well below the theoretical maximum of 100. New phosphor blends are proposed for use with LED chips emitting in the 350-450 nm range. The application of such blends can afford CRI values greater than 95, over the entire range of color temperatures of interest for general illumination (2500K - 8000K). In some cases, the CRI values approach the theoretical maximum of 100. LED based lamps with a steady state performance of 23 LPW and 25 lumens per chip at 3000K, with a general CRI (Ra) of 97 and a mean CRI (R1-R14) of 96 are demonstrated.

  18. High-output LED-based light engine for profile lighting fixtures with high color uniformity using freeform reflectors.

    PubMed

    Gadegaard, Jesper; Jensen, Thøger Kari; Jørgensen, Dennis Thykjær; Kristensen, Peter Kjær; Søndergaard, Thomas; Pedersen, Thomas Garm; Pedersen, Kjeld

    2016-02-20

    In the stage lighting and entertainment market, light engines (LEs) for lighting fixtures are often based on high-intensity discharge (HID) bulbs. Switching to LED-based light engines gives possibilities for fast switching, additive color mixing, a longer lifetime, and potentially, more energy-efficient systems. The lumen output of a single LED is still not sufficient to replace an HID source in high-output profile fixtures, but combining multiple LEDs can create an LE with a similar output, but with added complexity. This paper presents the results of modeling and testing such a light engine. Custom ray-tracing software was used to design a high-output red, green and blue LED-based light engine with twelve CBT-90 LEDs using a dual-reflector principle. The simulated optical system efficiency was 0.626 with a perfect (R=1) reflector coating for light delivered on a target surface through the entire optical system. A profile lighting fixture prototype was created, and provided an output of 6744 lumen and an efficiency of 0.412. The lower efficiency was mainly due to a non-optimal reflector coating, and the optimized design is expected to reach a significantly higher efficiency. PMID:26906589

  19. Design of multisegmented freeform lens for LED fishing/working lamp with high efficiency.

    PubMed

    Lai, Min-Feng; Anh, Nguyen Doan Quoc; Gao, Jia-Zhi; Ma, Hsin-Yi; Lee, Hsiao-Yi

    2015-10-01

    A novel LED fishing/working light is proposed to enhance the lighting efficiency of a fishing boat. The study is focused on the freeform secondary lens design so as to create a lamp that attracts fish and sheds light on the deck for the crew's work. The experimental results show that the proposed multisegmented freeform lens can deliver the proposed aim, giving 3 times as much illuminating power as the traditional high-intensity discharge fishing lamp does with the same input of electrical power. PMID:26479667

  20. High-performance LED luminaire for sports hall

    NASA Astrophysics Data System (ADS)

    Lee, Xuan-Hao; Yang, Jin-Tsung; Chien, Wei-Ting; Chang, Jung-Hsuan; Lo, Yi-Chien; Lin, Che-Chu; Sun, Ching-Cherng

    2015-09-01

    In this paper, we present a luminaire design with anti-glare and energy-saving effects for sports hall. Compared with traditional lamps using in a badminton court, the average illuminance on the ground of the proposed LED luminaire is enhanced about 300%. Besides, the uniformity is obviously enhanced and improved. The switch-on speed of lighting in sports hall is greatly reduced from 5-10 minutes to 1 second. The simulation analysis and the corresponding experiment results are demonstrated.

  1. High Efficacy Green LEDs by Polarization Controlled MOVPE

    SciTech Connect

    Wetzel, Christian

    2013-03-31

    Amazing performance in GaInN/GaN based LEDs has become possible by advanced epitaxial growth on a wide variety of substrates over the last decade. An immediate push towards product development and worldwide competition for market share have effectively reduced production cost and generated substantial primary energy savings on a worldwide scale. At all times of the development, this economic pressure forced very fundamental decisions that would shape huge industrial investment. One of those major aspects is the choice of epitaxial growth substrate. The natural questions are to what extend a decision for a certain substrate will limit the ultimate performance and to what extent, the choice of a currently more expensive substrate such as native GaN could overcome any of the remaining performance limitations. Therefore, this project has set out to explore what performance characteristic could be achieved under the utilization of bulk GaN substrate. Our work was guided by the hypotheses that line defects such as threading dislocations in the active region should be avoided and the huge piezoelectric polarization needs to be attenuated – if not turned off – for higher performing LEDs, particularly in the longer wavelength green and deep green portions of the visible spectrum. At their relatively lower performance level, deep green LEDs are a stronger indicator of relative performance improvements and seem particular sensitive to the challenges at hand.

  2. Light-Emitting Diodes (LED) for Primary Animal Habitat Lighting in Highly Controlled Environments

    NASA Technical Reports Server (NTRS)

    Winget, C. M.; Syrkin, N.; Heeke, D.; Mele, G.; Holley, D. C.; Dalton, Bonnie P. (Technical Monitor)

    1996-01-01

    Significant alterations in Biological Clock responses have been reported following sidereal time changes (e.g., Jet-lag), and exposure to microgravity (e.g., daytime sleepiness). Additionally, light reduces circulating melatonin (spectral specificity greatest between 450-500 nm). It was hypothesized that LEDs can replace the current light sources used in zero gravity and terrestrial research laboratories because of their small size, low mass, low energy consumption and long functional life. This report evaluates the capacity of LEDs to entrain the circadian system of rats as judged by measurement of overt behavioral circadian rhythms (activity, feeding, drinking). These data were collected in highly controlled environments similar to the shuttle Animal Enclosure Modules. Two groups were compared: control - animals exposed to standard cool-white fluorescent lights, and test - animals exposed to LEDs with a spectral power distribution matching the fluorescent lights. Gross locomotor activity, feeding and drinking frequencies were continuously monitored and stored at 10 minute intervals. Animals were exposed to the following photoperiods: 28 days of 12L:12D, 19 days of 24L:0D and 16 days of 12L:12D. Light intensities tested varied between 0.1 to 100 lux. Rats received food and water ad libitum, and temperature and humidity were controlled throughout the study. The general health status of all rats was acceptable for each day of this study. No incidents of aggressive behavior were observed. Growth, locomotor activity, food and water consumption were comparable for all groups of animals, i.e, the circadian characteristics of the animals under these conditions were comparable. These results indicate that LED arrays are as effective in maintaining circadian rhythm stability as the commonly used cool-white fluorescent light sources. LEDs with their flexible spectrum, low energy requirements and minimal heat production have advantages for some chronopharmacology studies and

  3. Nanoscale carrier injectors for high luminescence Si-based LEDs

    NASA Astrophysics Data System (ADS)

    Piccolo, G.; Kovalgin, A. Y.; Schmitz, J.

    2012-08-01

    In this paper we present the increased light emission for Si p-i-n light emitting diodes (LEDs) by geometrical scaling of the injector size for p- and n- type carriers. Simulations and electrical and optical characteristics of our realized devices support our findings. Reducing the injector size decreases the leakage of minority carriers in the injector regions, availing more carriers for effective radiative recombination in the intrinsic volume of the device. A comparison is made between reference large-scale and nano-size injector p-i-n diodes.

  4. Comparative Evaluation of the Effects of Light Intensities and Curing Cycles of QTH, and LED Lights on Microleakage of Class V Composite Restorations

    PubMed Central

    Chandurkar, Anshu M; Metgud, Sandeep S; Yakub, Shaikh Shoeb; Kalburge, Vaishali J; Biradar, Basawaraj C

    2014-01-01

    Background: The purpose of this study was to evaluate the effects of light intensity and curing cycles of QTH and LED lights on the microleakage of Class V composite restorations. Materials and Methods:Eighty freshly extracted human maxillary premolars were used for this study. Standardized Class V cavities were prepared and they were restored with microhybrid resin composite. According to the curing protocol, the teeth were then divided into 4 groups (n=20): QTH curing (standard and soft start modes), and LED (standard and soft start modes) irradiations. Microleakage was evaluated by immersion of the samples in 50% silver nitrate solution. The samples were then sectioned, evaluated under a stereomicroscope, and scored for microleakage. Results: The results of the present in-vitro study showed mean dye leakage scores of 1.9, 1.2, 1.45 and 0.90 for Group I (QTH-Standard mode), Group II (QTH-Soft Start mode), Group III (LED-Standard mode) and Group IV (LED-Soft Start mode) respectively. Conclusion: It was thus concluded that the soft start polymerization showed a highly significant difference as compared to the standard curing modes of QTH and LED lights, respectively. PMID:24783142

  5. High Intensity Polarized Electron Sources

    NASA Astrophysics Data System (ADS)

    Poelker, M.; Adderley, P.; Brittian, J.; Clark, J.; Grames, J.; Hansknecht, J.; McCarter, J.; Stutzman, M. L.; Suleiman, R.; Surles-Law, K.

    2008-02-01

    During the 1990s, at numerous facilities world wide, extensive R&D devoted to constructing reliable GaAs photoguns helped ensure successful accelerator-based nuclear and high-energy physics programs using spin polarized electron beams. Today, polarized electron source technology is considered mature, with most GaAs photoguns meeting accelerator and experiment beam specifications in a relatively trouble-free manner. Proposals for new collider facilities however, require electron beams with parameters beyond today's state-of-the-art and serve to renew interest in conducting polarized electron source R&D. And at CEBAF/Jefferson Lab, there is an immediate pressing need to prepare for new experiments that require considerably more beam current than before. One experiment in particular—Q-weak, a parity violation experiment that will look for physics beyond the Standard Model—requires 180 uA average current at polarization >80% for a duration of one year, with run-averaged helicity correlated current asymmetry less than 0.1 ppm. Neighboring halls will continue taking beam during Q-weak, pushing the total average beam current from the gun beyond 300 uA. This workshop contribution describes R&D at Jefferson Lab, dedicated toward extending the operating current of polarized electron sources to meet the requirements of high current experiments at CEBAF and to better appreciate the technological challenges of new accelerators, particularly high average current machines like eRHIC that require at least 25 mA at high polarization.

  6. High-Intensity Proton Accelerator

    SciTech Connect

    Jay L. Hirshfield

    2011-12-27

    Analysis is presented for an eight-cavity proton cyclotron accelerator that could have advantages as compared with other accelerators because of its potentially high acceleration gradient. The high gradient is possible since protons orbit in a sequence of TE111 rotating mode cavities of equally diminishing frequencies with path lengths during acceleration that greatly exceed the cavity lengths. As the cavities operate at sequential harmonics of a basic repetition frequency, phase synchronism can be maintained over a relatively wide injection phase window without undue beam emittance growth. It is shown that use of radial vanes can allow cavity designs with significantly smaller radii, as compared with simple cylindrical cavities. Preliminary beam transport studies show that acceptable extraction and focusing of a proton beam after cyclic motion in this accelerator should be possible. Progress is also reported on design and tests of a four-cavity electron counterpart accelerator for experiments to study effects on beam quality arising from variations injection phase window width. This device is powered by four 500-MW pulsed amplifiers at 1500, 1800, 2100, and 2400 MHz that provide phase synchronous outputs, since they are driven from a with harmonics derived from a phase-locked 300 MHz source.

  7. Hazards from High Intensity Lamps and Arcs

    NASA Technical Reports Server (NTRS)

    Sliney, D. H.

    1970-01-01

    The principal occupational health problem generally associated with high intensity arc lamps results from exposure of the eye and skin to ultraviolet radiation. Occasionally, the chorioretinal burns are of concern. The eye is generally more susceptible than the skin to injury from high intensity optical radiation sources whether ultraviolet, visible or infrared. Recent developments in technology have shown that some high intensity optical radiation sources which have output parameters greatly different from those encountered in the natural environment present a serious chorioretinal burn hazard.

  8. High Intensity Radiated Fields (HIRF) project plan

    NASA Astrophysics Data System (ADS)

    Glynn, Michael S.; Blair, Jerry T.; Hintze, M. Marx

    1991-09-01

    Addressed here is the Federal Aviation Administration's approach to High Intensity Radiated Fields (HIRF) affecting the aviation community. Near- and far-term tasks are described. Deliverables, program management, scheduling, and cost issues are discussed.

  9. Highly-efficient, tunable green, phosphor-converted LEDs using a long-pass dichroic filter and a series of orthosilicate phosphors for tri-color white LEDs.

    PubMed

    Oh, Ji Hye; Oh, Jeong Rok; Park, Hoo Keun; Sung, Yeon-Goog; Do, Young Rag

    2012-01-01

    This study introduces a long-pass dichroic filter (LPDF) on top of a phosphor-converted LED (pc-LED) packing associated with each corresponding tunable orthosilicate ((Ba,Sr)2SiO4:Eu) phosphor in order to fabricate tunable green pc-LEDs. These LPDF-capped green pc-LEDs provide luminous efficacies between 143–173 lm/W at 60 mA in a wavelength range between 515 and 560 nm. These tunable green pc-LEDs can replace green semiconductor-type III-V LEDs, which present challenges with respect to generating high luminous efficacy. We also introduce the highly-efficient tunable green pc-LEDs into tri-color white LED systems that combine an InGaN blue LED and green/red full down-converted pc-LEDs. The effect of peak wavelength in the tunable green pc-LEDs on the optical properties of a tri-color package white LED is analyzed to determine the proper wavelength of green color for tri-color white LEDs. The tri-color white LED provides excellent luminous efficacy (81.5–109 lm/W) and a good color rendering index (64–87) at 6500 K of correlated color temperature (CCT) with the peak wavelength of green pc-LEDs. The luminous efficacy of the LPDF-capped green monochromatic pc-LED and tri-color package with tunable green pc-LEDs can be increased by improving the external quantum efficiency of blue LEDs and the conversion efficiency of green pc-LEDs. PMID:22379669

  10. Near-ultraviolet LED of the External Quantum Efficiency Over 45% and its Application to High-color Rendering Phosphor Conversion White LEDs

    NASA Astrophysics Data System (ADS)

    Sakuta, Hiroaki; Fukui, Takeshi; Miyachi, Tsutomu; Kamon, Kunihito; Hayashi, Hideki; Nakamura, Nobutaka; Uchida, Yuji; Kurai, Satoshi; Taguchi, Tsunemasa

    Highly luminous efficiency and color rendering index (CRI) of 70 lm/W and 95 under low correlated color temperature (CCT) of 3177 K has been obtained by phosphor conversion (PC) white light-emitting diodes (LEDs) using near-ultra violet (n-UV) LEDs with the external quantum efficiency (EQE) of 46.7%. The homogeneous spatial color uniformity on chromaticity of PC white LEDs excited by n-UV LEDs are particularly adequate to the general lighting applications.

  11. A Psychologist-Led Educational Intervention Results in a Sustained Reduction in Neonatal Intensive Care Unit Infections

    PubMed Central

    Van Rostenberghe, Hans; Short, Jacki; Ramli, Noraida; Geok, Tan Beng; Subramaniam, Sivasangari; Che Yaakob, Che Anuar; Othman, Azizah; Ibrahim, Nor Rosidah; Ho, Jacqueline; Mohamed, Zeehaida; Hasan, Habsah

    2014-01-01

    Even though in the corporate world psychological science has been widely used, the formal use of evidence-based psychology in important areas of clinical medicine has been scanty at best. It was the aim of this study to determine the efficacy of a psychologist-led 2-week nurse educator training on the infection rate in the neonatal intensive care unit (NICU). Materials and methods: In 2007, six senior neonatal nurses underwent a training course focusing on the retrieval of evidence and knowledge of psychological principles that would allow them to share the evidence in such a way that evidence is effectively brought into practice. The course was led by a psychologist. The nurses created and delivered their own teaching modules, all focused on infection control. The rates of bacteremia, 2 years prior to intervention were analyzed and compared with the rate following the intervention for 3 years. Results: The immediate output of the course included three teaching modules: hand washing, sterile procedures, and general measures to control infection. These modules were subsequently administered to the NICU nurses in regular structured continuous nursing education sessions. The psychological techniques taught in the course were applied. Bacteremia in the NICU significantly decreased in the year of the course and the subsequent years when compared to previous years (from more than 17 in 2005 and 2006 to less than 10 per 100 admissions to the NICU in 2008 and 2009). Conclusion: This study suggests that a psychologist-led course, followed by a structured CNE can lead to a sustainable reduction in infection rates in a NICU. PMID:25478550

  12. High Efficiency LED Lamp for Solid-State Lighting

    SciTech Connect

    James Ibbetson

    2006-12-31

    This report contains a summary of technical achievements during a three-year project to demonstrate high efficiency, solid-state lamps based on gallium nitride/silicon carbide light-emitting diodes. Novel chip designs and fabrication processes are described for a new type of nitride light-emitting diode with the potential for very high efficiency. This work resulted in the demonstration of blue light-emitting diodes in the one watt class that achieved up to 495 mW of light output at 350 mA drive current, corresponding to quantum and wall plug efficiencies of 51% and 45%, respectively. When combined with a phosphor in Cree's 7090 XLamp package, these advanced blue-emitting devices resulted in white light-emitting diodes whose efficacy exceeded 85 lumens per watt. In addition, up to 1040 lumens at greater than 85 lumens per watt was achieved by combining multiple devices to make a compact white lamp module with high optical efficiency.

  13. Reflectors with directional-mixed reflection properties for application in luminaries with high-power LED diodes

    NASA Astrophysics Data System (ADS)

    Zaremba, Krzysztof

    2008-06-01

    Application of directional-mixed reflectors results in a luminance decrease of the apparent image of light emitting diodes (LEDs), which is advantageous as far as glare reduction is concerned. On the other hand, reflectors have a negative impact on luminous intensity curves of the luminaries. This work analyzes an impact of surfaces with directional-mixed reflection properties in a mirror reflector designed for a luminary equipped with high-power LEDs. We present an algorithm used to determine the shape of the reflector of the surface with small scattering, where the axis twist angle for a parabolic reflector varies in a predefined range and follows a power function.

  14. Arrays of microscopic organic LEDs for high-resolution optogenetics

    PubMed Central

    Steude, Anja; Witts, Emily C.; Miles, Gareth B.; Gather, Malte C.

    2016-01-01

    Optogenetics is a paradigm-changing new method to study and manipulate the behavior of cells with light. Following major advances of the used genetic constructs over the last decade, the light sources required for optogenetic control are now receiving increased attention. We report a novel optogenetic illumination platform based on high-density arrays of microscopic organic light-emitting diodes (OLEDs). Because of the small dimensions of each array element (6 × 9 μm2) and the use of ultrathin device encapsulation, these arrays enable illumination of cells with unprecedented spatiotemporal resolution. We show that adherent eukaryotic cells readily proliferate on these arrays, and we demonstrate specific light-induced control of the ionic current across the membrane of individual live cells expressing different optogenetic constructs. Our work paves the way for the use of OLEDs for cell-specific optogenetic control in cultured neuronal networks and for acute brain slices, or as implants in vivo. PMID:27386540

  15. Transparent composite electrode for high-efficiency polymer LEDs

    NASA Astrophysics Data System (ADS)

    Li, Lu; Yu, Zhibin; Liang, Jiajie; Chang, Chia-Hao; Hu, Weili; Pei, Qibing

    2012-09-01

    Polymer composite electrodes based on silver nanowires or carbon nanotubes have been prepared with transparency and surface conductivity approaching those of ITO/glass and better than ITO/PET. The conductive surface has an average roughness less than 10 nm, better than ITO/glass. Depending on the polymer matrix selected, the composite electrodes can be made rigid, flexible like polycarbonate, or stretchable like a rubber. Various polymer light emitting diodes,light emitting electrochemical cells and polymer solar cells have been fabricated using the composite electrode as anode, exhibiting electroluminescent efficiencies generally higher than control devices fabricated on ITO/glass. These polymer light emitting devices are all highly flexible and can be bent to less than 3 mm radius without loss of performance. With further modification of the composite electrodes, we have also demonstrated stretchable OLEDs wherein the emissive area can be elongated by as much as 50%.

  16. Arrays of microscopic organic LEDs for high-resolution optogenetics.

    PubMed

    Steude, Anja; Witts, Emily C; Miles, Gareth B; Gather, Malte C

    2016-05-01

    Optogenetics is a paradigm-changing new method to study and manipulate the behavior of cells with light. Following major advances of the used genetic constructs over the last decade, the light sources required for optogenetic control are now receiving increased attention. We report a novel optogenetic illumination platform based on high-density arrays of microscopic organic light-emitting diodes (OLEDs). Because of the small dimensions of each array element (6 × 9 μm(2)) and the use of ultrathin device encapsulation, these arrays enable illumination of cells with unprecedented spatiotemporal resolution. We show that adherent eukaryotic cells readily proliferate on these arrays, and we demonstrate specific light-induced control of the ionic current across the membrane of individual live cells expressing different optogenetic constructs. Our work paves the way for the use of OLEDs for cell-specific optogenetic control in cultured neuronal networks and for acute brain slices, or as implants in vivo. PMID:27386540

  17. Evaluation of an LED (Light-Emitting Diode) high-mounted signal lamp

    NASA Astrophysics Data System (ADS)

    Olson, P. L.

    1987-02-01

    Two studies are described evaluating high-mounted stoplights using light-emitting diodes (LEDs) compared with conventional incandescent units. The first of these studies obtained ratings from subjects who drove one car and followed another car that was equipped with the test lamps. The results indicate that the subjects generally preferred the LEDs to the conventional lamp. The second study was a laboratory evaluation of the attention-getting capabilities of LED and incandescent stoplights. Under all conditions tested subjects responded faster to the LED units. The response time advantage for the LED units increased with more difficult viewing conditions, such as high levels of illumination and long viewing distance. The results of these investigations are discussed in terms of the applicability of the LED technology to high mounted stoplights on motor vehicles.

  18. Advanced modeling of high intensity accelerators

    SciTech Connect

    Ryne, R.D.; Habib, S.; Wangler, T.P.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goals of this project were three-fold: (1) to develop a new capability, based on high performance (parallel) computers, to perform large scale simulations of high intensity accelerators; (2) to apply this capability to modeling high intensity accelerators under design at LANL; and (3) to use this new capability to improve the understanding of the physics of intense charge particle beams, especially in regard to the issue of beam halo formation. All of these goals were met. In particular, the authors introduced split-operator methods as a powerful and efficient means to simulate intense beams in the presence of rapidly varying accelerating and focusing fields. They then applied these methods to develop scaleable, parallel beam dynamics codes for modeling intense beams in linacs, and in the process they implemented a new three-dimensional space charge algorithm. They also used the codes to study a number of beam dynamics issues related to the Accelerator Production of Tritium (APT) project, and in the process performed the largest simulations to date for any accelerator design project. Finally, they used the new modeling capability to provide direction and validation to beam physics studies, helping to identify beam mismatch as a major source of halo formation in high intensity accelerators. This LDRD project ultimately benefited not only LANL but also the US accelerator community since, by promoting expertise in high performance computing and advancing the state-of-the-art in accelerator simulation, its accomplishments helped lead to approval of a new DOE Grand Challenge in Computational Accelerator Physics.

  19. Fundamental Physics Explored with High Intensity Laser

    NASA Astrophysics Data System (ADS)

    Tajima, T.; Homma, K.

    2012-10-01

    Over the last century the method of particle acceleration to high energies has become the prime approach to explore the fundamental nature of matter in laboratory. It appears that the latest search of the contemporary accelerator based on the colliders shows a sign of saturation (or at least a slow-down) in increasing its energy and other necessary parameters to extend this frontier. We suggest two pronged approach enabled by the recent progress in high intensity lasers. First we envision the laser-driven plasma accelerator may be able to extend the reach of the collider. For this approach to bear fruit, we need to develop the technology of high averaged power laser in addition to the high intensity. For this we mention that the latest research effort of ICAN is an encouraging sign. In addition to this, we now introduce the concept of the noncollider paradigm in exploring fundamental physics with high intensity (and large energy) lasers. One of the examples we mention is the laser wakefield acceleration (LWFA) far beyond TeV without large luminosity. If we relax or do not require the large luminosity necessary for colliders, but solely in ultrahigh energy frontier, we are still capable of exploring such a fundamental issue. Given such a high energetic particle source and high-intensity laser fields simultaneously, we expect to be able to access new aspects on the matter and the vacuum structure from fundamental physical point of views. LWFA naturally exploits the nonlinear optical effects in the plasma when it becomes of relativistic intensity. Normally nonlinear optical effects are discussed based upon polarization susceptibility of matter to external fields. We suggest application of this concept even to the vacuum structure as a new kind of order parameter to discuss vacuum-originating phenomena at semimacroscopic scales. This viewpoint unifies the following observables with the unprecedented experimental environment we envision; the dispersion relation of

  20. Case Study on Combination of Fluorescent Materials for White LED to Obtain High Color Rendering Indexes

    NASA Astrophysics Data System (ADS)

    Nayama, Shunsuke; Itoh, Kunio

    This letter reports on white-LED with high color rendering property. We realized the white-LED whose average Color Rendering Index (CRI) is as high as 94.2 by applying the commercial Red, Yellow, Green and Blue phosphors to near ultraviolet-LED. So far as we know, this value is the highest ever attained in white-LED around the color temperature of 5500[K]. In order to realize the good Ra (average CRI), we made a CRI simulator and simulated the spectrum distribution of white-LED with good Ra. The spectrum distribution obtained by this simulation was proved to be very useful as a landmark for realizing a prototype white-LED with good Ra.

  1. High-brightness low-power consumption microLED arrays

    NASA Astrophysics Data System (ADS)

    Bonar, James R.; Valentine, Gareth J.; Gong, Zheng; Small, James; Gorton, Steve

    2016-03-01

    microLED arrays are a route to providing emissive displays with high brightness and low power consumption performance. In this talk we will discuss results pertaining to sub 10 μm LED pixels, the challenges posed and performance achieved in forming microLED arrays. In particular, pixel pitch, backplane capabilities and colourisation. The applications which can benefit from this approach will also be discussed.

  2. Rapidly pulsed, high intensity, incoherent light source

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.; Brandhorst, H. W., Jr. (Inventor)

    1974-01-01

    A rapid pulsing, high intensity, incoherent light is produced by selectively energizing a plurality of discharge lamps with a triggering circuit. Each lamp is connected to a capacitor, and a power supply is electrically connected to all but one of the capacitors. This last named capacitor is electrically connected to a discharge lamp which is connected to the triggering circuit.

  3. Progress toward achieving high power and high efficiency semipolar LEDs and their characterization

    NASA Astrophysics Data System (ADS)

    Zhong, Hong

    Performance of current commercially available wurtzite nitride based light-emitting diodes (LEDs), grown along the polar (0001) c-plane orientation, is limited by the presence of polarization-related electric fields inside multi-quantum wells (MQWs). The discontinuities in both spontaneous and piezoelectric polarization at the heterointerfaces result in internal electric fields in the quantum wells. These electric fields cause carrier separation [quantum confined Stark effect (QCSE)] and reduce the radiative recombination rate within the quantum wells. One approach to reduce and possibly eliminate the polarization-related effects is to grow III-nitride devices on crystal planes that are inclined with respect to the c-axis, i.e., on semipolar planes. In this dissertation, metalorganic chemical vapor deposition (MOCVD) has been employed for the homoepitaxial growth of GaN based LEDs on semipolar orientations. As a consequence of growing on high-quality bulk GaN substrates, the LEDs have significantly reduced threading dislocation and stacking fault densities, resulting in remarkable improvements in EQE and output power. High efficiency semipolar (1011) violet-blue and blue LEDs have been demonstrated without any intentional effort to enhance the light extraction from those devices. Optimizations of epitaxial structures have led to increased output power and external quantum efficiency. A silicone encapsulated single quantum well blue LED with peak wavelength of 444 nm with output power of 24.3 mW, external quantum efficiency of 43% and luminous efficacy of 75 lm/W (with phosphorescent coating) at 20 mA has been demonstrated. Polarization fields in strained (1011) and (112¯2) InGaN quantum wells have been experimentally determined through bias-dependent optical studies. Our results show that the polarization field flips its direction in semipolar InGaN quantum wells with large inclination angles (i.e. around 60°). This suggests that there exists a polarization

  4. The NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Williams, Reuben A.

    1997-01-01

    High Intensity Radiated Fields (HIRF) are the result of a multitude of intentional and nonintentional electromagnetic sources that currently exists in the world. Many of today's digital systems are susceptible to electronic upset if subjected to certain electromagnetic environments (EME). Modern aerospace designers and manufacturers increasingly rely on sophisticated digital electronic systems to provide critical flight control in both military, commercial, and general aviation aircraft. In an effort to understand and emulate the undesired environment that high energy RF provides modern electronics, the Electromagnetics Research Branch (ERB) of the Flight Electronics and Technology Division (FETD) conducts research on RF and microwave measurement methods related to the understanding of HIRF. In the High Intensity Radiated Fields Laboratory, the effects of high energy radiating electromagnetic fields on avionics and electronic systems are tested and studied.

  5. Design of high-efficient freeform LED lens for road illumination

    NASA Astrophysics Data System (ADS)

    Moiseev, Mikhail A.; Doskolovich, Leonid L.; Kazanskiy, Nikolay L.

    2011-10-01

    The evolution of lighting devices based on light-emitting diodes (LEDs) leads to increase of energy efficiency of such devices and, as a partial case, increase of light efficiency of LED optics. The conventional LED optics with the only freeform refractive surface cannot provide high light efficiency for street- and road-illumination applications. The reason is the performance limitations of the refractive surface in terms of ray rotation. Exploiting the total internal reflection effect, we devised a novel design of LED optics allowing to reach the value of light efficiency up to 80%-90%. This paper details the work principle of our LED optics design and the methods of its surfaces computation. The simulation results show that the proposed LED secondary optics design provides light efficiency by 15.5% more than the conventional LED optics in the case of uniformly illuminated region with size of 40 meters by 8 meters. The usage of the proposed novel LED optics design makes possible to reduce the number of LED chips that are used in modern road lamps and, as a consequence, to reduce the power consumption of road lamps. Still, such optical elements have to be made and tested with real LED sources.

  6. High quality GaN-based LED epitaxial layers grown in a homemade MOCVD system

    NASA Astrophysics Data System (ADS)

    Haibo, Yin; Xiaoliang, Wang; Junxue, Ran; Guoxin, Hu; Lu, Zhang; Hongling, Xiao; Jing, Li; Jinmin, Li

    2011-03-01

    A homemade 7 × 2 inch MOCVD system is presented. With this system, high quality GaN epitaxial layers, InGaN/GaN multi-quantum wells and blue LED structural epitaxial layers have been successfully grown. The non-uniformity of undoped GaN epitaxial layers is as low as 2.86%. Using the LED structural epitaxial layers, blue LED chips with area of 350 × 350 μm2 were fabricated. Under 20 mA injection current, the optical output power of the blue LED is 8.62 mW.

  7. AGS RESONANT EXTRACTION WITH HIGH INTENSITY BEAMS.

    SciTech Connect

    AHRENS,L.; BROWN,K.; GLENN,J.W.; ROSER,T.; TSOUPAS,N.; VANASSELT,W.

    1999-03-29

    The Brookhaven AGS third integer resonant extraction system allows the AGS to provide high quality, high intensity 25.5 GeV/c proton beams simultaneously to four target stations and as many as 8 experiments. With the increasing intensities (over 7 x 10{sup 13} protons/pulse) and associated longer spill periods (2.4 to 3 seconds long), we continue to run with low losses and high quality low modulation continuous current beams.[1] Learning to extract and transport these higher intensity beams has required a process of careful modeling and experimentation. We have had to learn how to correct for various instabilities and how to better match extraction and the transport lines to the higher emittance beams being accelerated in the AGS. Techniques employed include ''RF'' methods to smooth out momentum distributions and fine structure. We will present results of detailed multi-particle tracking modeling studies which enabled us to develop a clear understanding of beam loss mechanisms in the transport and extraction process. We will report on our status, experiences, and the present understanding of the intensity limitations imposed by resonant extraction and transport to fixed target stations.

  8. Beam diagnostics for high intensity hadron accelerators

    NASA Astrophysics Data System (ADS)

    Ausset, Patrick; Gardès, Daniel

    2007-07-01

    High intensity hadron beam accelerators have been recently proposed and developed either for the production of high intensity secondary beams for Nuclear and Particle Physics research (EURISOL, SPIRAL2, FAIR), or Applied Physics in the field of Accelerator Driven System and waste transmutation (EUROTRANS). For these applications, high power Linear Accelerator (LINAC) are planned to produce and accelerate hadron beams up to 1 GeV. Both commissioning and operation of these accelerators require dedicated beam instrumentation able to monitor and characterize on line as completely as possible the produced beams having a power in the range of 1 MW. Beam current, transverse beam centroı¨d position and profiles and beam energy are the most important characteristics that have to be measured. Due to the high average power of the beam, nondestructive or at least minimally intercepting beam sensors are required. Beam instrumentation for IPHI (CEA/DSM and CNRS/IN2P3 collaboration) which is a high intensity proton (3 MeV, 100 mA, CW operation) injector initially designed to be a possible front end for this kind of LINAC is under realization. Beam diagnostics already under operation, developments in progress will be described and will introduce a more general description of high power beam instrumentation.

  9. Using Artificial Neural Networks Approach for the Color Enhance of High Power LEDs

    NASA Astrophysics Data System (ADS)

    Chen, Hsi-Chao; Wu, Guo-Yang; Yang, Chi-Hao; Chen, Peng-Ying; Lai, Mei-Jyun; Huang, Kuo-Ting

    2012-10-01

    High power light-emitting diodes (HP-LEDs) always are applied for energy-saving to replace the traditional light sources. HP-LEDs lighting has been regarded in the next generation lighting. In this study, the RGY colors enhance of whit LED lighting was researched and modulated by artificial neural network (ANN). An ANN model was used to investigate the correlated color temperature (CCT) and luminous flux (Lux) for the white LED enhanced with different power of single RYG LEDs. The starting color temperature of the white LED will be set at 7500K (D75 white light standard), then changed the voltage of the single LED of the red, green or yellow, respectively, to find the best tuning function for the color temperature and luminous efficiency. These results exhibited that changing the voltage of red LED had the broader color temperature from 7500 K to 1500 K than the range of green and yellow LEDs from 7500K to 8200K and 7500K to 4700K, respectively. Then, these experimental results were used as input data for the training model. After the learning model was completed, an analysis was used to obtain the internal representation of the color information by the responses of the individual chips of the three hidden units in the middle layer. Identification rate of data would be achieved to 100% by the neural network pattern-recognition tool. Anyway, the correlation coefficient could reach to 99% by the ANN fitting tool for the color enhancement.

  10. Ultra-high intensity laser plasma interactions

    NASA Astrophysics Data System (ADS)

    Langdon, A. Bruce; Hinkel, D. E.; Lasinski, Barbara F.; Still, C. H.

    1997-11-01

    In current studies of plasma interactions relevant to the fast ignitor concept,footnote M. Tabak, et al., Phys. Plasmas 1, 1626 (1994). an ultra-high intensity beam propagates through underdense, relativistically transparent, and then near solid density plasmas to create a channel. The ultra-high intensity beam propagates through this channel toward the compressed core where it creates hot electrons as it is absorbed. Three-dimensional fluid simulation(R. L. Berger et al), Phys. Fluids B, 2243 (1993). (with relativistic enhancements) studies of self-focusing in the underdense plasma will be reported and compared to PIC simulations in the same parameter regime. Beam structure near focus detracts from channel formation. Modeling in support of upcoming 100TW will be presented.

  11. Magnets for high intensity proton synchrotrons

    SciTech Connect

    Jean-Francois Ostiguy, Vladimir Kashikhine and Alexander Makarov

    2002-09-19

    Recently, there has been considerable interest at Fermilab for the Proton Driver, a future high intensity proton machine. Various scenarios are under consideration, including a superconducting linac. Each scenario present some special challenges. We describe here the magnets proposed in a recent study, the Proton Driver Study II, which assumes a conventional warm synchrotron, roughly of the size of the existing FNAL booster, but capable of delivering 380 kW at 8 GeV.

  12. Positron microanalysis with high intensity beams

    SciTech Connect

    Hulett, L.D. Jr.; Donohue, D.L.

    1990-01-01

    One of the more common applications for a high intensity slow positron facility will be microanalysis of solid materials. In the first section of this paper some examples are given of procedures that can be developed. Since most of the attendees of this workshop are experts in positron spectroscopy, comprehensive descriptions will be omitted. With the exception of positron emission microscopy, most of the procedures will be based on those already in common use with broad beams. The utility of the methods have all been demonstrated, but material scientists use very few of them because positron microbeams are not generally available. A high intensity positron facility will make microbeams easier to obtain and partially alleviate this situation. All microanalysis techniques listed below will have a common requirement, which is the ability to locate the microscopic detail or area of interest and to focus the positron beam exclusively on it. The last section of this paper is a suggestion of how a high intensity positron facility might be designed so as to have this capability built in. The method will involve locating the specimen by scanning it with the microbeam of positrons and inducing a secondary electron image that will immediately reveal whether or not the positron beam is striking the proper portion of the specimen. This scanning positron microscope' will be a somewhat prosaic analog of the conventional SEM. It will, however, be an indispensable utility that will enhance the practicality of positron microanalysis techniques. 6 refs., 1 fig.

  13. Accelerated life test for high-power white LED based on spectroradiometric measurement

    NASA Astrophysics Data System (ADS)

    Shen, Haiping; Pan, Jiangen; Feng, Huajun

    2008-03-01

    We implement an accelerated life test for the high-power white LEDs based on spectroradiometric measurement. The luminous flux degradation performances are investigated at both the rated current of 350mA and a higher current of 500mA. The average lifetime of the LEDs is 7057 hours at 350mA and 3508 hours at 500mA. The variations of the color of the white LEDs are studied. The color of the low quality white LEDs changes greatly, while the high quality white LEDs keep their color stable. The degradation performances of the chip and phosphor are studied separately. The quantum efficiency of the phosphor becomes lower from 350mA to 500mA current supply. The LED chip degrades faster than the phosphor during the 500mA high current aging. The luminous flux increase and the peak wavelength shift from 350mA to 500mA current supply are found to be useful lifetime indicating parameters that correlate well to the reliability of the high-power white LEDs.

  14. Light extraction technologies for high-efficiency GaInN-LED devices

    NASA Astrophysics Data System (ADS)

    Haerle, Volker; Hahn, Berthold; Kaiser, Stephan; Weimar, Andreas; Eisert, Dominik; Bader, Stefan; Ploessl, Andreas; Eberhard, Franz

    2003-07-01

    Data are presented for an GaInN based thinfilm LED. The LED is fabricated by transferring the epilayers with laser lift off from sapphire to a GaAs host substrate. In combination with efficient surface roughening and highly reflective p-mirror metallisation an extraction efficiency of 70% and wall plug efficiency of 24% at 460nm have been shown. The chips showed 12mW @ 20mA with a Voltage of 3.2V. The technology is scalable from small size LEDs to high current Chips and is being transferred to mass production.

  15. Spatially Resolved Thermal Analysis of High Power LEDs Using Thermoreflectance Microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Hexuan; Al-Hemyari, Kadhair; Yan, Susu; Summers, Joseph; Hudgings, Janice

    2012-02-01

    The efficiency, reliability, and lifetime of high power light emitting diodes (LEDs) depend critically on their operating temperature. The lateral temperature distribution is of particular importance with large area, high power LEDs as defects related to overheating in high power LEDs usually occur at a high rate at the surface. In this work, we present the use of lock-in thermoreflectance imaging to measure the spatially resolved surface thermal distribution of operating LEDs. This non-invasive thermography technique offers high spatial and thermal resolutions. We show that results of thermoreflectance surface temperature are quantitatively consistent with temperature measurements obtained using forward voltage bias and wavelength shift techniques. We demonstrate the power of spatially resolved thermoreflectance by imaging the highly non-uniform surface temperature distribution of an operating LED at high electrical bias power. We conclude that the non-uniform surface temperature distribution is resulted from non-uniformly distributed inject current and overheating at the contacts. We also investigate the thermal impact of encapsulating commercial LEDs with a plastic lens and silicone epoxy.

  16. Patient and Family Member-Led Research in the Intensive Care Unit: A Novel Approach to Patient-Centered Research

    PubMed Central

    Gill, Marlyn; Bagshaw, Sean M.; McKenzie, Emily; Oxland, Peter; Oswell, Donna; Boulton, Debbie; Niven, Daniel J.; Potestio, Melissa L.; Shklarov, Svetlana; Marlett, Nancy; Stelfox, Henry T.

    2016-01-01

    Introduction Engaging patients and family members as partners in research increases the relevance of study results and enhances patient-centered care; how to best engage patients and families in research is unknown. Methods We tested a novel research approach that engages and trains patients and family members as researchers to see if we could understand and describe the experiences of patients admitted to the intensive care unit (ICU) and their families. Former patients and family members conducted focus groups and interviews with patients (n = 11) and families of surviving (n = 14) and deceased (n = 7) patients from 13 ICUs in Alberta Canada, and analyzed data using conventional content analysis. Separate blinded qualitative researchers conducted an independent analysis. Results Participants described three phases in the patient/family “ICU journey”; admission to ICU, daily care in ICU, and post-ICU experience. Admission to ICU was characterized by family shock and disorientation with families needing the presence and support of a provider. Participants described five important elements of daily care: honoring the patient’s voice, the need to know, decision-making, medical care, and culture in ICU. The post-ICU experience was characterized by the challenges of the transition from ICU to a hospital ward and long-term effects of critical illness. These “ICU journey” experiences were described as integral to appropriate interactions with the care team and comfort and trust in the ICU, which were perceived as essential for a community of caring. Participants provided suggestions for improvement: 1) provide a dedicated family navigator, 2) increase provider awareness of the fragility of family trust, 3) improve provider communication skills, 4) improve the transition from ICU to hospital ward, and 5) inform patients about the long-term effects of critical illness. Analyses by independent qualitative researchers identified similar themes. Conclusions Patient

  17. High Efficiency m-plane LEDs on Low Defect Density Bulk GaN Substrates

    SciTech Connect

    David, Aurelien

    2012-10-15

    Solid-state lighting is a key technology for reduction of energy consumption in the US and worldwide. In principle, by replacing standard incandescent bulbs and other light sources with sources based on light-emitting diodes (LEDs), ultimate energy efficiency can be achieved. The efficiency of LEDs has improved tremendously over the past two decades, however further progress is required for solid- state lighting to reach its full potential. The ability of an LED at converting electricity to light is quantified by its internal quantum efficiency (IQE). The material of choice for visible LEDs is Gallium Nitride (GaN), which is at the basis of blue-emitting LEDs. A key factor limiting the performance of GaN LEDs is the so-called efficiency droop, whereby the IQE of the LED decreases significantly at high current density. Despite decades of research, efficiency droop remains a major issue. Since high-current operation is necessary for practical lighting applications, reducing droop is a major challenge for the scientific community and the LED industry. Our approach to solving the droop issue is the use of newly available low-defect-density bulk GaN non-polar substrates. In contrast to the standard foreign substrates (sapphire, silicon carbide, silicon) used in the industry, we have employed native bulk GaN substrates with very low defect density, thus ensuring exquisite material quality and high IQE. Whereas all commercial LEDs are grown along the c-plane crystal direction of GaN, we have used m-plane non-polar substrates; these drastically modify the physical properties of the LED and enable a reduction of droop. With this approach, we have demonstrated very high IQE performance and low droop. Our results focused on violet and blue LEDs. For these, we have demonstrated very high peak IQEs and current droops of 6% and 10% respectively (up to a high current density of 200A.cm-2). All these results were obtained under electrical operation. These high IQE and low droop

  18. High frame rate photoacoustic imaging using multiple wave-length LED array light source

    NASA Astrophysics Data System (ADS)

    Agano, Toshitaka; Sato, Naoto; Nakatsuka, Hitoshi; Kitagawa, Kazuo; Hanaoka, Takamitsu; Morisono, Koji; Shigeta, Yusuke; Tanaka, Chizuyo

    2016-03-01

    We have successfully imaged photoacoustic differences of light absorbance between two images acquired by different wave-length LED array light source. Compared to photoacoustic imaging system using conventional solid-state laser light source, LED light source can be driven at higher frequency pulses, so we were able to get the subtraction image at higher frame rate that calculated from two images which were captured at each wave-length LED light pulse timing. We developed LED array light source which is composed to have two different wave-length chips, so each wave-length light pulse can be controlled and emitted freely. Thus LED array light source can be composed as multiple selectable wavelength more than two, and a various combination of subtraction image may become available at high frame rate.

  19. A high efficiency and power factor, segmented linear constant current LED driver

    NASA Astrophysics Data System (ADS)

    Yongyuan, Li; Wei, Guo; Zhangming, Zhu

    2015-04-01

    A high efficiency, high power factor, and linear constant current LED driver based on adaptive segmented linear architecture is presented. When the input voltage varied, the proposed LED driver automatically switched over LED strings according to the segmented LED voltage drop, which increased the LED lighting time. The efficiency and power factor are improved, while the system design is simplified by this control scheme. Without the usage of electrolytic capacitor and magnetic components, the proposed driver possesses advantages of smaller size, longer lifetime and lower cost over others. The proposed driver is implemented in 0.8 μm 5 V/40 V HVCMOS process, which occupies an active area of 820 × 920 μm2. The measured results show that the average value of the internal reference voltage is 500 ± 7 mV, with a standard deviation of only 4.629 mV, thus LED current can be set accurately. Under 220 V root mean square 50 Hz utility voltage and the number ratio of the three LED strings being 47 : 17 : 16, the system can realize a high power factor of 0.974 and power conversion efficiency of 93.4%. Project supported by the National Natural Science Foundation of China (Nos. 61234002, 61322405, 61306044, 61376033).

  20. Spectral and luminous efficacy change of high-power LEDs under different dimming methods

    NASA Astrophysics Data System (ADS)

    Gu, Yimin; Narendran, Nadarajah; Dong, Tianming; Wu, Huiying

    2006-08-01

    Dimming is an important and necessary feature for light sources used in general lighting applications. An experimental study was conducted to quantify the spectral and luminous efficacy change of high-power colored and pc-white LEDs under continuous current reduction (CCR) and pulse-width modulation (PWM) dimming schemes. For InGaN-based blue, green, and pc-white LEDs, the peak wavelength shifts were in opposite directions for the two dimming schemes. The peak wavelength showed a blue shift with increased current, most likely due to band filling and QCSE dominated effects. InGaN LEDs exhibited red shifts with increased duty cycle, which is dominated by junction heat. AlInGaP red LEDs show mainly thermal-induced red shift with increased current or duty cycle. In addition, the luminous efficacy was always higher for the CCR dimming scheme at dimmed levels, irrespective of the LED type. Keywords: Light-emitting diodes (LEDs), white LEDs, mixed-color white LEDs, pulse-width modulation (PWM), continuous current reduction (CCR), peak wavelength shift, luminous efficacy

  1. Beam halo in high-intensity beams

    SciTech Connect

    Wangler, T.P. )

    1993-12-25

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. We describe what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. We present initial results from a study of beam entropy for an intense space-charge dominated beam.

  2. Beam halo in high-intensity beams

    SciTech Connect

    Wangler, T.P.

    1993-06-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam.

  3. Beam halo in high-intensity beams

    SciTech Connect

    Wangler, T.P.

    1993-01-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam.

  4. Ultrabroad linewidth orange-emitting nanowires LED for high CRI laser-based white lighting and gigahertz communications.

    PubMed

    Janjua, Bilal; Ng, Tien Khee; Zhao, Chao; Oubei, Hassan Makine; Shen, Chao; Prabaswara, Aditya; Alias, Mohd Sharizal; Alhamoud, Abdullah Ali; Alatawi, Abdullah Awaad; Albadri, Abdulrahman M; Alyamani, Ahmed Y; El-Desouki, Munir M; Ooi, Boon S

    2016-08-22

    Group-III-nitride laser diode (LD)-based solid-state lighting device has been demonstrated to be droop-free compared to light-emitting diodes (LEDs), and highly energy-efficient compared to that of the traditional incandescent and fluorescent white light systems. The YAG:Ce3+ phosphor used in LD-based solid-state lighting, however, is associated with rapid degradation issue. An alternate phosphor/LD architecture, which is capable of sustaining high temperature, high power density, while still intensity- and bandwidth-tunable for high color-quality remained unexplored. In this paper, we present for the first time, the proof-of-concept of the generation of high-quality white light using an InGaN-based orange nanowires (NWs) LED grown on silicon, in conjunction with a blue LD, and in place of the compound-phosphor. By changing the relative intensities of the ultrabroad linewidth orange and narrow-linewidth blue components, our LED/LD device architecture achieved correlated color temperature (CCT) ranging from 3000 K to above 6000K with color rendering index (CRI) values reaching 83.1, a value unsurpassed by the YAG-phosphor/blue-LD counterpart. The white-light wireless communications was implemented using the blue LD through on-off keying (OOK) modulation to obtain a data rate of 1.06 Gbps. We therefore achieved the best of both worlds when orange-emitting NWs LED are utilized as "active-phosphor", while blue LD is used for both color mixing and optical wireless communications. PMID:27557202

  5. Current development and patents on high-brightness white LED for illumination.

    PubMed

    Pang, Wen-Yuan; Lo, Ikai; Hsieh, Chia-Ho; Hsu, Yu-Chi; Chou, Ming-Chi; Shih, Cheng-Hung

    2010-01-01

    In this paper, we reviewed the current development and patents for the application of high-brightness and high-efficiency white light-emitting diode (LED). The high-efficiency GaN nanostructures, such as disk, pyramid, and rod were grown on LiAlO(2) substrate by plasma-assisted molecular-beam epitaxy, and a model was developed to demonstrate the growth of the GaN nanostructures. Based on the results, the GaN disk p-n junction was designed for the application of high brightness and high efficiency white LED. PMID:20214653

  6. The effects of student-led and teacher-led advance organizers on students' achievement and motivation of high school biology students

    NASA Astrophysics Data System (ADS)

    Hopkins, Melody Denise

    The purpose of this research study was to explore what effects student-led and teacher-led advance organizer's instruction had on students' achievement and motivation in a high school biology class. The study used three advance organizers - Venn diagrams, concept maps, and KWL charts. There was a total of 83 students who participated in this study, and were enrolled in four sections of high school biology. The students were divided into two groups using systematic matching and received different advance organizer's instruction. Two groups received student-led instruction using cooperative learning, whereas, the other two groups received teacher-led instruction. Each group received a pretest, Advance Organizer Motivation Survey, weekly advance organizer-based lessons and weekly advance organizer evaluations for six weeks, posttest, and Advance Organizer Motivation Survey. Pretest and posttest scores on the biology exam, weekly objective quizzes, and presurvey and postsurvey scores on the Advance Organizer Motivation Survey were collected. Statistical analyses found no overall statistically significant difference in achievement between groups. When looking at achievement results for redundant organizers it was found that the student-led group had a higher mean than the teacher-led group when working with concept maps. Furthermore, there was a statistically significant difference in students' motivation to learn and motivation to participate in student-led activities between groups. The student-led group reported higher motivation than the teacher-led group. In regard to motivation and kinds of advance organizers, Venn diagrams and concept maps showed a statistically significant difference between groups, with the student-led group possessing more motivated with those two kinds of advance organizers than the teacher-led group. Qualitative data were also collected through weekly advance organizer evaluations, Advance Organizer Motivation Survey, and focus groups. These

  7. High-power UV-LED degradation: Continuous and cycled working condition influence

    NASA Astrophysics Data System (ADS)

    Arques-Orobon, F. J.; Nuñez, N.; Vazquez, M.; Segura-Antunez, C.; González-Posadas, V.

    2015-09-01

    High-power (HP) UV-LEDs can replace UV lamps for real-time fluoro-sensing applications by allowing portable and autonomous systems. However, HP UV-LEDs are not a mature technology, and there are still open issues regarding their performance evolution over time. This paper presents a reliability study of 3 W UV-LEDs, with special focus on LED degradation for two working conditions: continuous and cycled (30 s ON and 30 s OFF). Accelerated life tests are developed to evaluate the influence of temperature and electrical working conditions in high-power LEDs degradation, being the predominant failure mechanism the degradation of the package. An analysis that includes dynamic thermal and optical HP UV-LED measurements has been performed. Static thermal and stress simulation analysis with the finite element method (FEM) identifies the causes of package degradation. Accelerated life test results prove that HP UV-LEDs working in cycled condition have a better performance than those working in continuous condition.

  8. High intensity, pulsed thermal neutron source

    DOEpatents

    Carpenter, J.M.

    1973-12-11

    This invention relates to a high intensity, pulsed thermal neutron source comprising a neutron-producing source which emits pulses of fast neutrons, a moderator block adjacent to the last neutron source, a reflector block which encases the fast neutron source and the moderator block and has a thermal neutron exit port extending therethrough from the moderator block, and a neutron energy- dependent decoupling reflector liner covering the interior surfaces of the thermal neutron exit port and surrounding all surfaces of the moderator block except the surface viewed by the thermal neutron exit port. (Official Gazette)

  9. High-efficiency isolated SEPIC converter with reduced conduction losses for LED displays

    NASA Astrophysics Data System (ADS)

    Choi, Woo-Young; Yang, Min-Kwon

    2014-11-01

    This paper proposes a high-efficiency isolated bridgeless single-ended primary inductor converter (SEPIC) for light-emitting-diode (LED) displays. The proposed isolated SEPIC converter can supply LED back-light power with reduced conduction losses. Switching power losses as well as conduction losses are reduced. The proposed converter is theoretically analysed. Experimental results based on a 28 V, 300 W back-light power are discussed to verify the performance of the proposed converter.

  10. Determining contrast sensitivity functions for monochromatic light emitted by high-brightness LEDs

    NASA Astrophysics Data System (ADS)

    Ramamurthy, Vasudha; Narendran, Nadarajah; Freyssinier, Jean Paul; Raghavan, Ramesh; Boyce, Peter

    2004-01-01

    Light-emitting diode (LED) technology is becoming the choice for many lighting applications that require monochromatic light. However, one potential problem with LED-based lighting systems is uneven luminance patterns. Having a uniform luminance distribution is more important in some applications. One example where LEDs are becoming a viable alternative and luminance uniformity is an important criterion is backlighted monochromatic signage. The question is how much uniformity is required for these applications. Presently, there is no accepted metric that quantifies luminance uniformity. A recent publication proposed a method based on digital image analysis to quantify beam quality of reflectorized halogen lamps. To be able to employ such a technique to analyze colored beams generated by LED systems, it is necessary to have contrast sensitivity functions (CSFs) for monochromatic light produced by LEDs. Several factors including the luminance, visual field size, and spectral power distribution of the light affect the CSFs. Although CSFs exist for a variety of light sources at visual fields ranging from 2 degrees to 20 degrees, CSFs do not exist for red, green, and blue light produced by high-brightness LEDs at 2-degree and 10-degree visual fields and at luminances typical for backlighted signage. Therefore, the goal of the study was to develop a family of CSFs for 2-degree and 10-degree visual fields illuminated by narrow-band LEDs at typical luminances seen in backlighted signs. The details of the experiment and the results are presented in this manuscript.

  11. High intensity discharge device containing oxytrihalides

    DOEpatents

    Lapatovich, W.P.; Keeffe, W.M.; Liebermann, R.W.; Maya, J.

    1987-06-09

    A fill composition for a high intensity discharge device including mercury, niobium oxytrihalide, and a molecular stabilization agent is provided. The molar ratio of niobium oxytrihalide to the molecular stabilization agent in the fill is in the range of from about 5:1 to about 7.5:1. Niobium oxytrihalide is present in the fill in sufficient amount to produce, by dissociation in the discharge, atomic niobium, niobium oxide, NbO, and niobium dioxide, NbO[sub 2], with the molar ratio of niobium-containing vapor species to mercury in the fill being in the range of from about 0.01:1 to about 0.50:1; and mercury pressure of about 1 to about 50 atmospheres at lamp operating temperature. There is also provided a high intensity discharge device comprising a sealed light-transmissive arc tube; the arc tube including the above-described fill; and an energizing means for producing an electric discharge within the arc tube. 7 figs.

  12. High intensity discharge device containing oxytrihalides

    DOEpatents

    Lapatovich, Walter P.; Keeffe, William M.; Liebermann, Richard W.; Maya, Jakob

    1987-01-01

    A fill composition for a high intensity discharge device including mercury, niobium oxytrihalide, and a molecular stabilization agent is provided. The molar ratio of niobium oxytrihalide to the molecular stabilization agent in the fill is in the range of from about 5:1 to about 7.5:1. Niobium oxytrihalide is present in the fill in sufficient amount to produce, by dissociation in the discharge, atomic niobium, niobium oxide, NbO, and niobium dioxide, NbO.sub.2, with the molar ratio of niobium-containing vapor species to mercury in the fill being in the range of from about 0.01:1 to about 0.50:1; and mercury pressure of about 1 to about 50 atmospheres at lamp operating temperature. There is also provided a high intensity discharge device comprising a sealed light-transmissive arc tube; the arc tube including the above-described fill; and an energizing means for producing an electric discharge within the arc tube.

  13. The High-efficiency LED Driver for Visible Light Communication Applications

    NASA Astrophysics Data System (ADS)

    Gong, Cihun-Siyong Alex; Lee, Yu-Chen; Lai, Jyun-Liang; Yu, Chueh-Hao; Huang, Li Ren; Yang, Chia-Yen

    2016-08-01

    This paper presents a LED driver for VLC. The main purpose is to solve the low data rate problem used to be in switching type LED driver. The GaN power device is proposed to replace the traditional silicon power device of switching LED driver for the purpose of increasing switching frequency of converter, thereby increasing the bandwidth of data transmission. To achieve high efficiency, the diode-connected GaN power transistor is utilized to replace the traditional ultrafast recovery diode used to be in switching type LED driver. This work has been experimentally evaluated on 350-mA output current. The results demonstrate that it supports the data of PWM dimming level encoded in the PPM scheme for VLC application. The experimental results also show that system’s efficiency of 80.8% can be achieved at 1-Mb/s data rate.

  14. Development of UV-LED Phosphor Coatings for High Efficiency Solid State Lighting

    SciTech Connect

    U. Happek

    2005-01-01

    The University of Georgia, in collaboration with GE Global Research, is investigating the relevant quenching mechanism of phosphor coatings used in white light devices based on UV LEDs in a focused eighteen month program. The final goal is the design of high-efficacy white UV-LEDs through improved and optimized phosphor coatings. At the end of the first year, we have reached a fundamental understanding of quenching processes in UV-LED phosphors and have observed severe quenching in standard devices under extreme operating conditions. Relationships are being established that describe the performance of the phosphor as a function of photon flux, temperature, and phosphor composition. These relationships will provide a road map for the design of efficient white light LEDs during the final six months of the project.

  15. Design and development of a high-power LED-pumped Ce:Nd:YAG laser.

    PubMed

    Villars, Brenden; Steven Hill, E; Durfee, Charles G

    2015-07-01

    By studying quasi-continuous wave (QCW) operation of a Ce:Nd:YAG solid-state laser directly pumped by LED arrays, we demonstrate the feasibility of direct-LED pumping as an alternative to direct-diode or flashlamp pumping. LEDs emitting either at 460 or 810 nm were used to pump an uncooled Ce:Nd:YAG laser rod (at 30-Hz repetition rate for tens of seconds). Pumping at 460 nm was made possible by the Ce(3+) co-dopant that enables transfer of excitations near to Nd(3+) ions in the YAG lattice. Comparison of these two pumping schemes has allowed for a thorough analysis of the performance and efficiency of this laser system. QCW output energies as high as 18 mJ/pulse are reported, which to the best of our knowledge is the highest output pulse energy achieved by an LED-pumped solid-state laser to date. PMID:26125364

  16. The High-efficiency LED Driver for Visible Light Communication Applications

    PubMed Central

    Gong, Cihun-Siyong Alex; Lee, Yu-Chen; Lai, Jyun-Liang; Yu, Chueh-Hao; Huang, Li Ren; Yang, Chia-Yen

    2016-01-01

    This paper presents a LED driver for VLC. The main purpose is to solve the low data rate problem used to be in switching type LED driver. The GaN power device is proposed to replace the traditional silicon power device of switching LED driver for the purpose of increasing switching frequency of converter, thereby increasing the bandwidth of data transmission. To achieve high efficiency, the diode-connected GaN power transistor is utilized to replace the traditional ultrafast recovery diode used to be in switching type LED driver. This work has been experimentally evaluated on 350-mA output current. The results demonstrate that it supports the data of PWM dimming level encoded in the PPM scheme for VLC application. The experimental results also show that system’s efficiency of 80.8% can be achieved at 1-Mb/s data rate. PMID:27498921

  17. The High-efficiency LED Driver for Visible Light Communication Applications.

    PubMed

    Gong, Cihun-Siyong Alex; Lee, Yu-Chen; Lai, Jyun-Liang; Yu, Chueh-Hao; Huang, Li Ren; Yang, Chia-Yen

    2016-01-01

    This paper presents a LED driver for VLC. The main purpose is to solve the low data rate problem used to be in switching type LED driver. The GaN power device is proposed to replace the traditional silicon power device of switching LED driver for the purpose of increasing switching frequency of converter, thereby increasing the bandwidth of data transmission. To achieve high efficiency, the diode-connected GaN power transistor is utilized to replace the traditional ultrafast recovery diode used to be in switching type LED driver. This work has been experimentally evaluated on 350-mA output current. The results demonstrate that it supports the data of PWM dimming level encoded in the PPM scheme for VLC application. The experimental results also show that system's efficiency of 80.8% can be achieved at 1-Mb/s data rate. PMID:27498921

  18. High-power, high-intensity laser propagation and interactions

    SciTech Connect

    Sprangle, Phillip; Hafizi, Bahman

    2014-05-15

    This paper presents overviews of a number of processes and applications associated with high-power, high-intensity lasers, and their interactions. These processes and applications include: free electron lasers, backward Raman amplification, atmospheric propagation of laser pulses, laser driven acceleration, atmospheric lasing, and remote detection of radioactivity. The interrelated physical mechanisms in the various processes are discussed.

  19. Advanced technologies for high-efficiency GaInN LEDs for solid state lighting

    NASA Astrophysics Data System (ADS)

    Harle, Volker; Hahn, Berthold; Baur, Johannes; Fehrer, Michael; Weimar, Andreas; Kaiser, Stephan; Eisert, Dominik; Eberhard, Franz; Plossl, Andreas; Bader, Stefan

    2004-01-01

    Solid state lighting has seen a rapid development over the last decade. They compete and even outperform light sources like incandescent bulbs and halogen lamps. LEDs are used in applications where brightness, power consumption, reliability and costs are key parameters as automotive, mobile and display applications. In the future LEDs will also enter the market of general lighting. For all of these new applications highly efficient, scalable and cost efficient technologies are required. These targets can be matched by SiC based flip chip LEDs which enable the design of high current chips with efficiencies of up to 28 lm/W in white solderable packages. An alternative approach is the implementation of thinfilm technology for GaInN. The LED is fabricated by transferring the epilayers with laser lift off from sapphire to a GaAs host substrate. In combination with efficient surface roughening and highly reflective p-mirror metalization an extraction efficiency of 70% and wall plug efficiency of 24% at 460 nm have been shown. The chips showed 16 mW @ 20 mA with a Voltage of 3.2 V. The technology is scalable from small size LEDs to high current Chips and is being transferred to mass production.

  20. Experimental study on high-power LEDs integrated with micro heat pipe

    NASA Astrophysics Data System (ADS)

    LI, Cong-ming; Zhou, Chuan-peng; Luo, Yi; Hamidnia, Mohammad; Wang, Xiao-dong; You, Bo

    2016-01-01

    Micro heat pipe (MHP) is applied to implement the efficient heat transfer of light emitting diode (LED) device. The fabrication of MHP is based on micro-electro-mechanical-system (MEMS) technique, 15 micro grooves were etched on one side of silicon (Si) substrate, which was then packaged with aluminum heat sink to form an MHP. On the other side of Si substrate, three LED chips were fixed by die bonding. Then experiments were performed to study the thermal performance of this LED device. The results show that the LED device with higher filling ratio is better when the input power is 1.0 W; with the increase of input power, the optimum filling ratio changes from 30% to 48%, and the time reaching stable state is reduced; when the input power is equal to 2.5 W, only the LED device with filling ratio of 48% can work normally. So integrating MHP into high-power LED device can implement the effective control of junction temperature.

  1. HIGH-INTENSITY, HIGH CHARGE-STATE HEAVY ION SOURCES

    SciTech Connect

    ALESSI,J.G.

    2004-08-16

    There are many accelerator applications for high intensity heavy ion sources, with recent needs including dc beams for RIA, and pulsed beams for injection into synchrotrons such as RHIC and LHC. The present status of sources producing high currents of high charge state heavy ions is reviewed. These sources include ECR, EBIS, and Laser ion sources. Benefits and limitations for these type sources are described. Possible future improvements in these sources are also mentioned.

  2. Nonlinear Mechanisms of Lesion Formation by High Intensity Focused Ultrasound

    NASA Astrophysics Data System (ADS)

    Khokhlova, V. A.; Bailey, M. R.; Reed, J.; Canney, M. S.; Kaczkowski, P. J.; Crum, L. A.

    2006-05-01

    Nonlinear mechanisms of lesion formation by high intensity focused ultrasound (HIFU) were investigated experimentally and numerically in a transparent polyacrylamide gel phantom. Numerical predictions were made with a finite-amplitude acoustic propagation model. A 2-MHz transducer of 42-mm diameter and 44.5-mm radius of curvature was operated above the cavitation threshold of the gel phantom at various peak acoustic powers and duty cycles. Acoustic waveforms were recorded in the gel by a fiber optic hydrophone. Bubble activity was detected actively by B-mode diagnostic imaging, passively by a remote focused hydrophone, and optically by CCD and high-speed cameras. Elevated static pressure was applied to suppress bubble activity and increase the boiling temperature, thus isolating the pure effect of acoustic nonlinearity. In overpressure experiment performed at 32 W acoustic power, both cavitation and nonlinear ultrasound propagation accelerated lesion inception and growth, but acoustic nonlinearity, which led to shock formation, played the dominant role. Rapid localized heating, particularly by increased absorption in the shocked wave, led to boiling and then to proximal growth and migration of the lesion even at low overpressure. At 90W acoustic power, boiling was observed and predicted in less than 50 ms.

  3. Applications of High Intensity Proton Accelerators

    NASA Astrophysics Data System (ADS)

    Raja, Rajendran; Mishra, Shekhar

    2010-06-01

    Superconducting radiofrequency linac development at Fermilab / S. D. Holmes -- Rare muon decay experiments / Y. Kuno -- Rare kaon decays / D. Bryman -- Muon collider / R. B. Palmer -- Neutrino factories / S. Geer -- ADS and its potential / J.-P. Revol -- ADS history in the USA / R. L. Sheffield and E. J. Pitcher -- Accelerator driven transmutation of waste: high power accelerator for the European ADS demonstrator / J. L. Biarrotte and T. Junquera -- Myrrha, technology development for the realisation of ADS in EU: current status & prospects for realisation / R. Fernandez ... [et al.] -- High intensity proton beam production with cyclotrons / J. Grillenberger and M. Seidel -- FFAG for high intensity proton accelerator / Y. Mori -- Kaon yields for 2 to 8 GeV proton beams / K. K. Gudima, N. V. Mokhov and S. I. Striganov -- Pion yield studies for proton driver beams of 2-8 GeV kinetic energy for stopped muon and low-energy muon decay experiments / S. I. Striganov -- J-Parc accelerator status and future plans / H. Kobayashi -- Simulation and verification of DPA in materials / N. V. Mokhov, I. L. Rakhno and S. I. Striganov -- Performance and operational experience of the CNGS facility / E. Gschwendtner -- Particle physics enabled with super-conducting RF technology - summary of working group 1 / D. Jaffe and R. Tschirhart -- Proton beam requirements for a neutrino factory and muon collider / M. S. Zisman -- Proton bunching options / R. B. Palmer -- CW SRF H linac as a proton driver for muon colliders and neutrino factories / M. Popovic, C. M. Ankenbrandt and R. P. Johnson -- Rapid cycling synchrotron option for Project X / W. Chou -- Linac-based proton driver for a neutrino factory / R. Garoby ... [et al.] -- Pion production for neutrino factories and muon colliders / N. V. Mokhov ... [et al.] -- Proton bunch compression strategies / V. Lebedev -- Accelerator test facility for muon collider and neutrino factory R&D / V. Shiltsev -- The superconducting RF linac for muon

  4. Energy-Efficient, High-Color-Rendering LED Lamps Using Oxyfluoride and Fluoride Phosphors

    SciTech Connect

    Setlur, A.; Radkov, E; Henderson, C; Her, J; Srivastava, A; Karkada, N; Kishore, M; Kumar, N; Aesram, D; et al.

    2010-01-01

    LED lamps using phosphor downconversion can be designed to replace incandescent or halogen sources with a 'warm-white' correlated color temperature (CCT) of 2700-3200 K and a color rendering index (CRI) greater than 90. However, these lamps have efficacies of {approx}70% of standard 'cool-white' LED packages (CCT = 4500-6000 K; CRI = 75-80). In this report, we describe structural and luminescence properties of fluoride and oxyfluoride phosphors, specifically a (Sr,Ca){sub 3}(Al,Si)O{sub 4}(F,O):Ce{sup 3+} yellow-green phosphor and a K{sub 2}TiF{sub 6}:Mn{sup 4+} red phosphor, that can reduce this gap and therefore meet the spectral and efficiency requirements for high-efficacy LED lighting. LED lamps with a warm-white color temperature (3088 K), high CRI (90), and an efficacy of {approx}82 lm/W are demonstrated using these phosphors. This efficacy is {approx}85% of comparable cool-white lamps using typical Y{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+}-based phosphors, significantly reducing the efficacy gap between warm-white and cool-white LED lamps that use phosphor downconversion.

  5. High intensity neutrino oscillation facilities in Europe

    NASA Astrophysics Data System (ADS)

    Edgecock, T. R.; Caretta, O.; Davenne, T.; Densam, C.; Fitton, M.; Kelliher, D.; Loveridge, P.; Machida, S.; Prior, C.; Rogers, C.; Rooney, M.; Thomason, J.; Wilcox, D.; Wildner, E.; Efthymiopoulos, I.; Garoby, R.; Gilardoni, S.; Hansen, C.; Benedetto, E.; Jensen, E.; Kosmicki, A.; Martini, M.; Osborne, J.; Prior, G.; Stora, T.; Melo Mendonca, T.; Vlachoudis, V.; Waaijer, C.; Cupial, P.; Chancé, A.; Longhin, A.; Payet, J.; Zito, M.; Baussan, E.; Bobeth, C.; Bouquerel, E.; Dracos, M.; Gaudiot, G.; Lepers, B.; Osswald, F.; Poussot, P.; Vassilopoulos, N.; Wurtz, J.; Zeter, V.; Bielski, J.; Kozien, M.; Lacny, L.; Skoczen, B.; Szybinski, B.; Ustrycka, A.; Wroblewski, A.; Marie-Jeanne, M.; Balint, P.; Fourel, C.; Giraud, J.; Jacob, J.; Lamy, T.; Latrasse, L.; Sortais, P.; Thuillier, T.; Mitrofanov, S.; Loiselet, M.; Keutgen, Th.; Delbar, Th.; Debray, F.; Trophine, C.; Veys, S.; Daversin, C.; Zorin, V.; Izotov, I.; Skalyga, V.; Burt, G.; Dexter, A. C.; Kravchuk, V. L.; Marchi, T.; Cinausero, M.; Gramegna, F.; De Angelis, G.; Prete, G.; Collazuol, G.; Laveder, M.; Mazzocco, M.; Mezzetto, M.; Signorini, C.; Vardaci, E.; Di Nitto, A.; Brondi, A.; La Rana, G.; Migliozzi, P.; Moro, R.; Palladino, V.; Gelli, N.; Berkovits, D.; Hass, M.; Hirsh, T. Y.; Schaumann, M.; Stahl, A.; Wehner, J.; Bross, A.; Kopp, J.; Neuffer, D.; Wands, R.; Bayes, R.; Laing, A.; Soler, P.; Agarwalla, S. K.; Cervera Villanueva, A.; Donini, A.; Ghosh, T.; Gómez Cadenas, J. J.; Hernández, P.; Martín-Albo, J.; Mena, O.; Burguet-Castell, J.; Agostino, L.; Buizza-Avanzini, M.; Marafini, M.; Patzak, T.; Tonazzo, A.; Duchesneau, D.; Mosca, L.; Bogomilov, M.; Karadzhov, Y.; Matev, R.; Tsenov, R.; Akhmedov, E.; Blennow, M.; Lindner, M.; Schwetz, T.; Fernández Martinez, E.; Maltoni, M.; Menéndez, J.; Giunti, C.; González García, M. C.; Salvado, J.; Coloma, P.; Huber, P.; Li, T.; López Pavón, J.; Orme, C.; Pascoli, S.; Meloni, D.; Tang, J.; Winter, W.; Ohlsson, T.; Zhang, H.; Scotto-Lavina, L.; Terranova, F.; Bonesini, M.; Tortora, L.; Alekou, A.; Aslaninejad, M.; Bontoiu, C.; Kurup, A.; Jenner, L. J.; Long, K.; Pasternak, J.; Pozimski, J.; Back, J. J.; Harrison, P.; Beard, K.; Bogacz, A.; Berg, J. S.; Stratakis, D.; Witte, H.; Snopok, P.; Bliss, N.; Cordwell, M.; Moss, A.; Pattalwar, S.; Apollonio, M.

    2013-02-01

    The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Fréjus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of μ+ and μ- beams in a storage ring. The far detector in this case is a 100 kt magnetized iron neutrino detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular He6 and Ne18, also stored in a ring. The far detector is also the MEMPHYS detector in the Fréjus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Based on this, it has determined the physics reach of each facility, in particular for the measurement of CP violation in the lepton sector, and estimated the cost of construction. These have demonstrated that the best facility to build is the Neutrino Factory. However, if a powerful proton driver is constructed for another purpose or if the MEMPHYS detector is built for astroparticle physics, the Super Beam also becomes very attractive.

  6. Numerical simulation and optimization of enhanced heat transfer for high power LED light

    NASA Astrophysics Data System (ADS)

    Ge, Pu; Peng, Xu; Houchao, Miao; Li, Zhang

    2013-07-01

    A mathematical model of high power LED lights heat transfer was established, in which heat transfer structure of heat pipe was simplified based on the equivalent thermal resistance network model, and numerically solved by using the CFD software, the steady state temperature distributions were obtained. The simulation results indicate that ambient air temperature, the number of heat pipe, the thickness of bond coating, and the size of radiator play important roles for LED chip temperature, however, the influence of copper sink thickness is negligible. The heat transfer structure was optimized based on these results, and the optimized structure can achieve a better balance between cost reducing and heat transfer enhancement.

  7. Analysis of a passive heat sink for temperature stabilization of high-power LED bulbs

    NASA Astrophysics Data System (ADS)

    Balvís, Eduardo; Bendaña, Ricardo; Michinel, Humberto; Fernández de Córdoba, Pedro; Paredes, Angel

    2015-04-01

    In this paper we present a numerical analysis and experimental measurements of the temperature stabilization of high-power LED chips that we have obtained by employing an aluminum passive heat sink, designed to be used in a compact light bulb configuration. We demonstrate that our system keeps the temperature of the LED chip well-below 70° C yielding long-term operation of the device. Our simulations have been performed for a low-cost device ready to install in public streetlights. The experimental measurements performed in different configurations show a nice agreement with the numerical calculations.

  8. Low-Cost Substrates for High-Performance Nanorod Array LEDs

    SciTech Connect

    Sands, Timothy; Stach, Eric; Garcia, Edwin

    2009-04-30

    The completed project, entitled Low-Cost Substrates for High-Performance Nanorod LEDs, targeted the goal of a phosphor-free nanorod-based white LED with IQE > 50% across the spectrum from 450 nm to 600 nm on metallized silicon substrates. The principal achievements of this project included: Demonstration of (In,Ga)N nanopyramid heterostructures by a conventional OMVPE process. Verification of complete filtering of threading dislocations to yield dislocation-free pyramidal heterostructures. Demonstration of electroluminescence with a peak wavelength of ~600 nm from an (In,Ga)N nanopyramid array LED. Development of a reflective ZrN/AlN buffer layer for epitaxial growth of GaN films and GaN nanopyramid arrays on (111)Si.

  9. High-power LED illumination system for photosynthetic research on potted plant canopies

    NASA Astrophysics Data System (ADS)

    Thestrup, Birgitte; Dam-Hansen, Carsten; Lund, Janni B.; Rosenqvist, Eva

    2008-02-01

    The high energy efficiency and radiant flux of high-power LED devices has lead to many new applications of LED lighting. Within the more production oriented applied plant research, there is a need for illumination systems that ensures a high irradiance, spectral control and homogeneous illumination of a large plant canopy to ensure reproducible results over long term measurements. A new high power LED illumination system is presented. It has been designed and developed for illumination of a plant canopy area of 60 x 80 cm2 in a climate chamber where photosynthesis of the whole canopy can be measured. The LED system extends the precise control of the chamber climate with computer control and long term stability of the irradiance and spectral composition of the illumination. High-power red and blue (at 455 and 639 nm) LED devices have been chosen that coincides with the absorption peaks of chlorophyll. The illumination system allows for a maximum irradiance of 6.3 W/cm2 corresponding to a photosynthetic photon flux density (PPFD) of 300 μmol m -2 s -1. The spectral composition of the light given by the ratio of blue photons compared to the total number of red and blue photons can be adjusted from 0-40 % keeping the irradiance at a constant level. Spectroradiometric 2D grid measurement at the plant top level shows homogeneity of +/- 5% of the irradiance and +/- 5% of the spectral distribution, over almost the entire canopy area. Initial experiments carried out on Chrysanthemum plants showing the dependence of the photosynthesis on blue light fraction is presented and discussed.

  10. Portable, high intensity isotopic neutron source provides increased experimental accuracy

    NASA Technical Reports Server (NTRS)

    Mohr, W. C.; Stewart, D. C.; Wahlgren, M. A.

    1968-01-01

    Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy.

  11. High-Intensity Sweeteners and Energy Balance

    PubMed Central

    Swithers, Susan E.; Martin, Ashley A.; Davidson, Terry L.

    2010-01-01

    Recent epidemiological evidence points to a link between a variety of negative health outcomes (e.g. metabolic syndrome, diabetes and cardiovascular disease) and the consumption of both calorically sweetened beverages and beverages sweetened with high-intensity, non-caloric sweeteners. Research on the possibility that non-nutritive sweeteners promote food intake, body weight gain, and metabolic disorders has been hindered by the lack of a physiologically-relevant model that describes the mechanistic basis for these outcomes. We have suggested that based on Pavlovian conditioning principles, consumption of non-nutritive sweeteners could result in sweet tastes no longer serving as consistent predictors of nutritive postingestive consequences. This dissociation between the sweet taste cues and the caloric consequences could lead to a decrease in the ability of sweet tastes to evoke physiological responses that serve to regulate energy balance. Using a rodent model, we have found that intake of foods or fluids containing non-nutritive sweeteners was accompanied by increased food intake, body weight gain, accumulation of body fat, and weaker caloric compensation, compared to consumption of foods and fluids containing glucose. Our research also provided evidence consistent with the hypothesis that these effects of consuming saccharin may be associated with a decrement in the ability of sweet taste to evoke thermic responses, and perhaps other physiological, cephalic phase, reflexes that are thought to help maintain energy balance. PMID:20060008

  12. High-intensity sweeteners and energy balance.

    PubMed

    Swithers, Susan E; Martin, Ashley A; Davidson, Terry L

    2010-04-26

    Recent epidemiological evidence points to a link between a variety of negative health outcomes (e.g. metabolic syndrome, diabetes and cardiovascular disease) and the consumption of both calorically sweetened beverages and beverages sweetened with high-intensity, non-caloric sweeteners. Research on the possibility that non-nutritive sweeteners promote food intake, body weight gain, and metabolic disorders has been hindered by the lack of a physiologically-relevant model that describes the mechanistic basis for these outcomes. We have suggested that based on Pavlovian conditioning principles, consumption of non-nutritive sweeteners could result in sweet tastes no longer serving as consistent predictors of nutritive postingestive consequences. This dissociation between the sweet taste cues and the caloric consequences could lead to a decrease in the ability of sweet tastes to evoke physiological responses that serve to regulate energy balance. Using a rodent model, we have found that intake of foods or fluids containing non-nutritive sweeteners was accompanied by increased food intake, body weight gain, accumulation of body fat, and weaker caloric compensation, compared to consumption of foods and fluids containing glucose. Our research also provided evidence consistent with the hypothesis that these effects of consuming saccharin may be associated with a decrement in the ability of sweet taste to evoke thermic responses, and perhaps other physiological, cephalic phase, reflexes that are thought to help maintain energy balance. PMID:20060008

  13. BEAM LOSS MECHANISMS IN HIGH INTENSITY LINACS

    SciTech Connect

    Plum, Michael A

    2012-01-01

    In the present operation of the Oak Ridge Spallation Neutron Source, 60-Hz, 825-us H beam pulses are accelerated to 910 MeV, and then compressed to less than a microsecond in the storage ring, to deliver 1 MW of beam power to the spallation target. The beam loss in the superconducting portion of the linac is higher than expected, and it has shown a surprising counter-intuitive correlation with quadrupole magnetic fields, with a loss minimum occurring when the quadrupoles are set to approximately half their design values. This behavior can now be explained by a recent set of experiments that show the beam loss is primarily due to intra-beam stripping. Beam halo is another important beam loss contributor, and collimation in the 2.5 MeV Medium Energy Beam Transport has proven to be an effective mitigation strategy. In this presentation, we will summarize these and other beam loss mechanisms that are important for high intensity linacs.

  14. Physics of intense, high energy radiation effects.

    SciTech Connect

    Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart

    2011-02-01

    This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic calculations, the

  15. High Color-Rendering-index Hybrid White LEDs Employing CdSe/ZnS Core/Shell Quantum Dots.

    PubMed

    Chang, Yajing; Sun, Dapeng; Zhang, Zhongping; Zhang, Yugang; Yao, Xudong; Jiang, Danlu; Yu, Yalan; Mi, Longfei; Chen, Lei; Zhong, Honghai; Jiang, Yang

    2016-01-01

    Hybrid white LEDs were constructed by leveraging a combination of CdSe/ZnS core/shell QDs and YAG: Ce³⁺ phosphors. The CdSe/ZnS core/shell QDs were synthesized by a two-step process in which CdSe QDs were first prepared via a hot-injection method, followed by ZnS coating through a facile single-molecular precursor approach. The resultant red-emitting CdSe/ZnS QDs showed decent fluorescent quantum yielding (36%). The resultant hybrid white LEDs--that based on CdSe/ZnS QDs and solid-state-reaction-processed YAG: Ce³⁺ phosphors--showed good luminescence properties, including bright warm light, a high color rendering index of 91.3, a low color temperature of 4965 K and a luminous efficiency of 44.22 lm/W. Moreover, increased luminous intensity has been observed in the presence of increased forward current without luminescence saturation, promising an ideal approach to construct warm-white LEDs with excellent color rendering properties. PMID:27398506

  16. High-speed analog achromatic intensity modulator.

    PubMed

    Stockley, J E; Sharp, G D; Doroski, D; Johnson, K M

    1994-05-15

    We report what is to our knowledge the first implementation of a broadband analog intensity modulator composed of two chiral smectic liquid-crystal half-wave retarders. A reflection-mode intensity modulator employing a single active device has also demonstrated achromatic transmission. A quantitative theory for chromatic compensation is presented. By optimum selection of liquid-crystal retardance and orientation, intensity transmission is uniform throughout the visible. The chiral smectic liquid-crystal devices used in the implementation are capable of switching in less than 20 micros. PMID:19844436

  17. Color and contrast sensitivity after glare from high-brightness LEDs

    NASA Astrophysics Data System (ADS)

    Reidenbach, H.-D.

    2008-02-01

    The color contrast capability was investigated for 3 volunteers with 7 specially developed test charts in red, green, blue, cyan, magenta, yellow and black as a reference, namely without and after glare from 4 colored high-brightness LEDs. Each subject completed 56 tests in order to check especially the ability to discriminate low contrast. It was found that a contrast decrease of one level is equivalent to an increase of about 4 s in the required identification time and in addition a delay time between about 14 s and 16 s has been measured at the beginning of the respective test as a result of the dazzling glare from an LED. In addition trials have been performed with 4 different pseudoisochromatic color plates designed by Ishihara for color vision. These plates have been used to determine temporary color deficiencies after an exposure from a high-brightness LED. For this purpose 40 volunteers have been included in a laboratory test. Color vision was impaired for periods between 27 s and 186 s depending on the applied color plate and respective LED color.

  18. High-power LEDs based on InGaAsP/InP heterostructures

    SciTech Connect

    Rakovics, V.; Imenkov, A. N.; Sherstnev, V. V.; Serebrennikova, O. Yu.; Il’inskaya, N. D.; Yakovlev, Yu. P.

    2014-12-15

    High-power light-emitting diodes (LEDs) with mesa diameters of 100, 200, and 300 μm are developed on the basis of InGaAsP/InP heterostructures. The mesas are close in shape to a truncated cone with a generatrix inclination angle of ∼45° in the vicinity of the active region of the LED, with a ring etched around the mesa serving as a reflector. The emission spectra and directivity patterns of these LEDs are studied in a wide range of current densities and it is shown that radiative recombination is dominant to a current density of ∼5000 A/cm{sup 2}, which makes these structures promising for the development of high-power LEDs. An emission power of ∼14 mW is obtained in the continuous-wave mode (I = 0.2 A, λ = 1.1 μm), and that of 77 mW, in the pulsed mode (I = 2 A, λ = 1.1 μm), which corresponds to external quantum efficiencies of 6.2 and 3.4%, respectively.

  19. Design and optimization of dielectric optical coatings for GaN based high bright LEDs

    NASA Astrophysics Data System (ADS)

    Wang, Xiaodong; Li, Yan; Yang, Hua; Yi, Xiaoyan; Wang, Liangchen; Wang, Guohong; Yang, Fuhua; Li, Jinmin

    2008-03-01

    Different types of dielectric optical coatings for GaN based high bright LEDs were designed and discussed. The optical coatings included the anti-reflection (AR) coating, high-reflection (HR) coating, and omni-directional high reflection coating. Main materials for the optical coatings were dielectric materials such as SiO II, Ta IIO 5 and Al IIO 3, which were different from the metallic reflector such as Ag usually used now. For the application of anti-reflection coating in GaN LEDs, it was introduced into the design of transparent electrodes with transparent materials such as ITO to form combined transparent electrodes. With the design of P, N transparent electrodes using the AR coating and ITO for GaN LEDs, the extraction efficiency was improved by about 15% experimentally. For the dielectric high-reflection coating, it has higher reflectivity and lower absorption than the metal reflector, and it was supposed to improve the extraction efficiency obviously. While the dielectric omni-directional reflection coating using dielectric materials was also designed and discussed in this article, since which was anticipated to improve the extraction efficiency furthermore. Using SiO II and Ta IIO 5, the average reflectivity of a design of all dielectric omni-directional high reflection coating on the sapphire surface was over 94%.

  20. High intensity ultrasound effects on meat brining.

    PubMed

    Cárcel, J A; Benedito, J; Bon, J; Mulet, A

    2007-08-01

    Pork loin (longissimus dorsi) samples of two different geometries, cylinders and slabs, were immersed in saturated NaCl brine for 45min under different conditions: without brine agitation (STAT), with brine agitation (AG) and with ultrasound application (US) at eight levels of ultrasonic intensity. Moisture content change and NaCl gain were considered in order to evaluate the difference in the brining treatments. No significant differences were found in moisture and NaCl content of samples treated under STAT conditions and AG conditions, while the influence of ultrasound on the mass transfer process during meat brining depended on the intensity applied. There was an ultrasonic intensity threshold above which the influence of ultrasound appeared. At the highest level of intensity studied, the water content of samples was significantly higher than the initial water content of meat. As regards NaCl transfer, once above the intensity threshold, the increase in the NaCl content was proportional to the applied ultrasonic intensity. Not statistically significant differences were found for sample geometry. PMID:22061236

  1. High-Efficiency Non-Polar GaN-Based LEDs

    SciTech Connect

    Paul Fini

    2010-11-30

    Inlustra Technologies with subcontractor U.C. Santa Barbara conducted a project with the principle goal of demonstrating high internal quantum efficiency blue (430 nm) and green (540nm) light emitting diodes (LEDs) on low-defect density non-polar GaN wafers. Inlustra pursued the fabrication of smooth thick a-plane and m-plane GaN films, as well as defect reduction techniques such as lateral epitaxial overgrowth (LEO) to uniformly lower dislocation density in these films. Limited free-standing wafers were produced as well. By the end of the reporting period, Inlustra had met its milestone of dislocation reduction to < 5 x 10{sup 6} cm{sup -2}. Stacking faults were still present in appreciable density ({approx} 1 x 10{sup 5} cm{sup -1}), but were not the primary focus of defect reduction since there have been no published studies establishing their detrimental effects on LED performance. Inlustra's LEO progress built a solid foundation upon which further commercial development of GaN substrates will occur. UCSB encountered multiple delays in its LED growth and fabrication efforts due to unavoidable facilities outages imposed by ongoing construction in an area adjacent to the metalorganic chemical vapor deposition (MOCVD) laboratory. This, combined with the large amount of ab initio optimization required for the MOCVD system used during the project, resulted in unsatisfactory LED progress. Although numerous blue-green photoluminescence results were obtained, only a few LED structures exhibited electroluminescence at appreciable levels. UCSB also conducting extensive modeling (led by Prof. Van de Walle) on the problem of non-radiative Auger recombination in GaN-based LED structures, which has been posited to contribute to LED efficiency 'droop' at elevated current density. Unlike previous modeling efforts, UCSB's approach was truly a first-principles ab initio methodology. Building on solid numerical foundations, the Auger recombination rates of In{sub x}Ga{sub 1-x

  2. Nurse-led intensive interventions improve adherence to continuous positive airway pressure therapy and quality of life in obstructive sleep apnea patients

    PubMed Central

    Chen, Xiaofen; Chen, Weiting; Hu, Weijie; Huang, Kui; Huang, Jing; Zhou, Yu

    2015-01-01

    Background Continuous positive airway pressure (CPAP) is widely recommended for the treatment of sleep apnea/hypopnea syndrome (SAHS), but its usage by patients is very low. The aim of this study was to assess intensive educational programs and nursing support for the improvement of CPAP use and outcomes in SAHS patients. Methods Eighty new SAHS patients were randomized to receive nurse-led intensive interventions or usual support at hospital and home. The main outcome measure was CPAP use; changes in sleeping, symptoms, mood, and quality of life were also assessed after 12 months of treatment. Results All outcome measures were improved after treatment in both groups. However, patients receiving intensive support with significantly higher CPAP use (higher daily CPAP usage by 2.2 hours/day) had greater improvements in SAHS symptoms and mood (P<0.05). The intervention group further showed an improvement in the Short Form-36 domains of mental and physical health (P<0.05). Conclusion The CPAP usage and quality of life can be significantly improved by nurse-led intensive program in obstructive sleep apnea patients. PMID:26648703

  3. [Analysis on the degradation of optical properties of high power white LED].

    PubMed

    Zhou, Zhou; Feng, Shi-Wei; Guo, Chun-Sheng; Zhang, Guang-Chen; Wu, Yan-Yan

    2012-10-01

    One watt white light emitting diodes (LEDs) were made by GaN-based blue light chips. The chips were coated by YAG phosphor and transparent silica gel. Current of 900 mA as electrical stress was carried on the LED samples and the optical properties of the samples were observed by measuring the main optical parameters during the aging test. After 4 200 hours of aging, the luminous flux rate of LEDs declined by a factor between 15% and 18%. Changes in I-V curves indicated the increase in leakage current, which were caused by the increase in defect density. Radiant flux of the blue light drawn from the spectrogram didn't decrease while the yellow light decreased obviously, which implies the degradation of conversion efficiency of YAG phosphor. Reasons for the increase in color temperature and keeping constant in color rendering index (CRI) were theoretically analyzed. The results of the experiment will provide a reference to the illumination applications of the high power white LED. PMID:23285849

  4. Effects of various LED light wavelengths and intensities on microalgae-based simultaneous biogas upgrading and digestate nutrient reduction process.

    PubMed

    Zhao, Yongjun; Wang, Juan; Zhang, Hui; Yan, Cheng; Zhang, Yuejin

    2013-05-01

    Biogas is a well-known, primary renewable energy source, but its utilizations are possible only after upgrading. The microalgae-based bag photo-bioreactor utilized in this research could effectively upgrade biogas and simultaneously reduce the nutrient content in digestate. Red light was determined as the optimal light wavelength for microalgae growth, biogas upgrading, and digestate nutrient reduction. In the range of moderate light intensities (i.e., 800, 1200, 1600, and 2000 μmol m(-2) s(-1)), higher light intensities achieved higher biogas upgrade and larger digestate nutrient reduction. Methane content attained the highest value of 92.74±3.56% (v/v). The highest chemical oxygen demand, total nitrogen, and total phosphorus reduction efficiency of digestate were 85.35±1.04%, 77.98±1.84%, and 73.03±2.14%, respectively. Considering the reduction and economic efficiencies of the carbon dioxide content of biogas and digestate nutrient as well as the biogas upgrading standard, the optimal light intensity range was determined to be from 1200 to 1600 μmol m(-2) s(-1). PMID:23567717

  5. Reflective optics design for an LED high beam headlamp of motorbikes.

    PubMed

    Ge, Peng; Wang, Xiang; Li, Yang; Wang, Hong

    2015-01-01

    We propose a reflective optics design for an LED motorbike high beam lamp. We set the measuring screen as an elliptical zone and divide it into many small lattices and divide the spatial angle of the LED source into many parts and make relationships between them. According to the conservation law of energy and the Snell's law, the reflector is generated by freeform optics design method. Then the optical system is simulated by Monte Carlo method using ASAP software. Light pattern of simulation could meet the standard. The high beam headlamp is finally fabricated and assembled into a physical object. Experiment results can fully comply with United Nations Economic Commission for Europe (ECE) vehicle regulations R113 revision 2 (Class C). PMID:25961073

  6. Proton shock acceleration using a high contrast high intensity laser

    NASA Astrophysics Data System (ADS)

    Gauthier, Maxence; Roedel, Christian; Kim, Jongjin; Aurand, Bastian; Curry, Chandra; Goede, Sebastian; Propp, Adrienne; Goyon, Clement; Pak, Art; Kerr, Shaun; Ramakrishna, Bhuvanesh; Ruby, John; William, Jackson; Glenzer, Siegfried

    2015-11-01

    Laser-driven proton acceleration is a field of intense research due to the interesting characteristics of this novel particle source including high brightness, high maximum energy, high laminarity, and short duration. Although the ion beam characteristics are promising for many future applications, such as in the medical field or hybrid accelerators, the ion beam generated using TNSA, the acceleration mechanism commonly achieved, still need to be significantly improved. Several new alternative mechanisms have been proposed such as collisionless shock acceleration (CSA) in order to produce a mono-energetic ion beam favorable for those applications. We report the first results of an experiment performed with the TITAN laser system (JLF, LLNL) dedicated to the study of CSA using a high intensity (5x1019W/cm2) high contrast ps laser pulse focused on 55 μm thick CH and CD targets. We show that the proton spectrum generated during the interaction exhibits high-energy mono-energetic features along the laser axis, characteristic of a shock mechanism.

  7. Intensity correlation of ionizing background at high redshifts

    NASA Technical Reports Server (NTRS)

    Zuo, Lin

    1993-01-01

    Intensity correlation of ionizing background at high redshifts is discussed. The intensity correlation function xi(sub j) and the absorption line equivalent width correlation xi(sub 1/W) are discussed.

  8. High-Power Warm-White Hybrid LED Package for Illumination

    SciTech Connect

    Soer, Wouter

    2013-09-19

    In this project, an integrated warm-white hybrid light engine was developed. The hybrid approach involves combining phosphor-converted off-white InGaN LEDs and direct-emitting red AlInGaP LEDs in a single light engine to achieve high efficacy together with high color rendering index. We developed and integrated technology improvements in InGaN and AlInGaP die technology, phosphor technology, package architecture and encapsulation, to realize a hybrid warm-white LED package with an efficacy of 140 lm/W at a correlated color temperature of 3000K and a color rendering index of 90, measured under representative operating conditions. This efficacy is 26% higher than the best warm-white LEDs of similar specification that are commercially available at the end of the project. Since the InGaN- and AlInGaP-based LEDs used in the hybrid engine show different behavior as a function of current and temperature, a control system needs to be in place to ensure a stable color point over all operating conditions. In this project, we developed an electronic control circuit that is fully integrated into the light engine in such a way that the module can simply be driven by a conventional single-channel driver. The integrated control circuit uses a switch-mode boost converter topology to control the LED drive currents based on the temperature and the input current of the light engine. A color control performance of 5 SDCM was demonstrated, and improvement to 3 SDCM is considered well within reach. The combination of high efficacy and ease of integration with existing single-channel drivers is expected to facilitate the adoption of the hybrid technology and accelerate the energy savings associated with solid-state lighting. In the product commercialization plan, downlights and indirect-lit troffers have been selected as the first target applications for this product concept. Fully functional integrated prototypes have been developed for both applications, and the business case

  9. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Not Available

    1990-01-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  10. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1990-10-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  11. High-performance epoxy casting resins for SMD-LED packaging

    NASA Astrophysics Data System (ADS)

    Bogner, Georg; Debray, Alexandra; Hoehn, Klaus

    2000-04-01

    In order to come up with high volume SMD-LED production encompassing 1.9 billion devices for current fiscal year we did basic exploratory work to establish structure-processing- property relations for robust epoxy casting resin packages with identical ppm level of one. Bisphenol A-based epoxy casting resins (DGEBA) with acidic ester modified Hexahydrophthalic anhydride (HHPA) hardeners using strictly controlled high-grade raw materials were formulated and thermally transferred to highly transparent polyester networks. For 1 mm thick samples transparency in the 400 to 800 nm region is above 90%. Thermal aging tests for 6 weeks at 120 degrees Celsius reveal only slight discoloration with a color distance of 2. To avoid significant light losses within the LED operating life of 100,000 hrs stress on mechanically sensitive light-emitting chips was reduced by matching glass transition temperature Tg and E-modulus to 115 degrees Celsius and 2,800 MPa, respectively. Total chloride content below 1,000 ppm imply low corrosion potential. Further, resin composition, epoxy-hardener mixing ratio as well as curing profile were adapted to materialize fast curing for demand quantities while introducing effective low stress moieties in the final structure. Low internal stress, superior thermal shock and crack resistance were derived from supreme fracture toughness: KIC and GIC values were 1.350 MPam1/2 and 560 J/m2. With favorable water absorption behavior LED-packages withstand all soldering processes including TTW (through the wave) soldering. Thus, SMD-LEDs fulfill electronic industry standard JEDEC LEVEL 2.

  12. Performances of BNL high-intensity synchrotrons

    SciTech Connect

    Weng, W.T.

    1998-03-01

    The AGS proton synchrotron was completed in 1960 with initial intensity in the 10 to the 10th power proton per pulse (ppp) range. Over the years, through many upgrades and improvements, the AGS now reached an intensity record of 6.3 {times} 10{sup 13} ppp, the highest world intensity record for a proton synchrotron on a single pulse basis. At the same time, the Booster reached 2.2 {times} 10{sup 13} ppp surpassing the design goal of 1.5 {times} 10{sup 13} ppp due to the introduction of second harmonic cavity during injection. The intensity limitation caused by space charge tune spread and its relationship to injection energy at 50 MeV, 200 MeV, and 1,500 MeV will be presented as well as many critical accelerator manipulations. BNL currently participates in the design of an accumulator ring for the SNS project at Oak Ridge. The status on the issues of halo formation, beam losses and collimation are also presented.

  13. A generalized approach to modeling radiation pattern measurement methods for high-power LEDs

    NASA Astrophysics Data System (ADS)

    Chang, Gao-Wei; Liao, Chia-Cheng; Chen, Yung-Chang

    2010-05-01

    The rapid growth of high-power light-emitting diode (LED) technologies has gained momentum in developing accurate tools and methods to measure performances of such products. For instance, it is widely recognized that confirming the photobiological safety is extremely important since the light of the high-power products may be shone directly into people's eyes. For many years, the international standard organizations, such as CIE, and researchers have been developing guidelines and/or improving methods for measuring the LED radiation patterns, respectively. However, the difficulties in LED measurements have been still highlighted by discrepancies in the experimental results among different laboratories. In this paper, we first propose a mathematical formulation for the existing approaches, such as those using two- and three-dimensional goniometers. Then, generalization of the measurement methods is presented to improve the system measurement accuracy, through making a connection between a predicted accuracy and the parameters of the optical setups (such as aperture size and working distance). To verify the effectiveness of our approach, the experiments are conducted to evaluate and compare the performances of the proposed approach. The measurement results indicate that our approach is consistent from theory to practice.

  14. Low-noise moisture meter with high-speed LED techniques

    NASA Astrophysics Data System (ADS)

    Aikio, Rami; Lindström, Hannu; Suopajärvi, Pekka; Malinen, Jouko; Mäntylä, Markku

    2010-04-01

    Near infrared (NIR) spectroscopy can provide inexpensive, rapid and contact-free chemical content measurements for on-line, hand-held and laboratory applications. Traditionally multiwavelength NIR analyzers are based on incandescent lamp light sources with rotating filter wheels, even though designs relying on lamp technology and moving parts mean larger size, require frequent maintenance and eventually limit measurement speed of the system. Today, optical power and available wavelength range of LEDs enable their use in chemical content analyzers. In this publication, a paper moisture meter with high speed LED techniques is presented. A prototype developed at VTT utilizes an extended InGaAs detector to measure diffuse reflection at four NIR wavelengths ranging from 1.2 to 2.1 μm. Source LED currents are amplitude modulated with fixed sinusoidal frequencies. Optical signals at each wavelength are demodulated from the detector signal using real-time digital lock-in detection method on an FPGA. Moisture content is calculated and displayed on the embedded platform. The design allows very high speed operation, where the result is updated every 1 ms. Performance of the prototype system was studied by measuring a set of known sealed paper samples. Paper moisture measurement accuracy was 0.14, repeatability 0.01 and 2σ noise 0.04 moisture percent. Laboratory tests showed that channel crosstalk after detection is below background noise level. The measured signal-to-noise ratios per channel were 70 - 85 dB when all LEDs were on. The overall performance equals the level of incandescent lamp based on-line moisture meters currently in use in paper mill and process automation. The developed system forms a good basis also for other content measurements.

  15. Degradation Physics of High Power LEDs in Outdoor Environment and the Role of Phosphor in the degradation process

    NASA Astrophysics Data System (ADS)

    Singh, Preetpal; Tan, Cher Ming

    2016-04-01

    A moisture- electrical – temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs without phosphor) and white LEDs (LEDs with phosphor) are found to be different, under both the power on (i.e. with 350 mA through each LED) and power off (i.e. without current supply) conditions. Difference in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed. The findings indicate that the proposed MET test is necessary for the LED industry in evaluating the reliability of LEDs under practical outdoor usage environment.

  16. Degradation Physics of High Power LEDs in Outdoor Environment and the Role of Phosphor in the degradation process.

    PubMed

    Singh, Preetpal; Tan, Cher Ming

    2016-01-01

    A moisture- electrical - temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs without phosphor) and white LEDs (LEDs with phosphor) are found to be different, under both the power on (i.e. with 350 mA through each LED) and power off (i.e. without current supply) conditions. Difference in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed. The findings indicate that the proposed MET test is necessary for the LED industry in evaluating the reliability of LEDs under practical outdoor usage environment. PMID:27052103

  17. Degradation Physics of High Power LEDs in Outdoor Environment and the Role of Phosphor in the degradation process

    PubMed Central

    Singh, Preetpal; Tan, Cher Ming

    2016-01-01

    A moisture- electrical – temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs without phosphor) and white LEDs (LEDs with phosphor) are found to be different, under both the power on (i.e. with 350 mA through each LED) and power off (i.e. without current supply) conditions. Difference in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed. The findings indicate that the proposed MET test is necessary for the LED industry in evaluating the reliability of LEDs under practical outdoor usage environment. PMID:27052103

  18. The design of a wireless batteryless biflash installation with high power LEDs

    NASA Astrophysics Data System (ADS)

    Cappelle, J.; De Geest, W.; Hanselaer, P.

    2011-05-01

    Adding flashlights at crosswalks may make these weak traffic points safer. Unfortunately plugging in traffic lights into the electrical grid is expensive and complex. This paper reports about the energetic, the electronic and the optical design and building of a wireless and batteryless biflash installation in the framework of a flemish SME supporting program. The energy is supplied by a small solar panel and is buffered by supercapacitors instead of batteries. This has the advantage of being maintenance free: the number of charge-discharge cycles is almost unlimited because there is no chemical reaction involved in the storage mechanism. On the other hand the limited energy storage capacity of supercapacitors requires a new approach for the system design. Based on the EN-12352 standard for warning light devices, all design choices were filled in to be as energy efficient as possible. The duty cycle and the light output of the high power led flashlights are minimized. The components for the electronic circuits for the led driver, the control and the RF communication are selected based on their energy consumption and power management techniques are implemented. A lot of energy is saved by making the biflash system active. The leds are only flashing on demand or at preprogrammed moments. A biflash installation is typically installed at both sides of a crosswalk. A call at one of the sides should result in flashing at both sides. To maintain the drag and drop principle, a wireless RF communication system is designed.

  19. Single-crystal phosphors for high-brightness white LEDs/LDs

    NASA Astrophysics Data System (ADS)

    Víllora, Encarnación G.; Arjoca, Stelian; Inomata, Daisuke; Shimamura, Kiyoshi

    2016-03-01

    White light-emitting diodes (wLEDs) are the new environmental friendly sources for general lighting purposes. For applications requiring a high-brightness, current wLEDs present overheating problems, which drastically decrease their emission efficiency, color quality and lifetime. This work gives an overview of the recent investigations on single-crystal phosphors (SCPs), which are proposed as novel alternative to conventional ceramic powder phosphors (CPPs). This totally new approach takes advantage of the superior properties of single-crystals in comparison with ceramic materials. SCPs exhibit an outstanding conversion efficiency and thermal stability up to 300°C. Furthermore, compared with encapsulated CPPs, SCPs possess a superior thermal conductivity, so that generated heat can be released efficiently. The conjunction of all these characteristics results in a low temperature rise of SCPs even under high blue irradiances, where conventional CPPs are overheated or even burned. Therefore, SCPs represent the ideal, long-demanded all-inorganic phosphors for high-brightness white light sources, especially those involving the use of high-density laser-diode beams.

  20. Recovery Act: Low-Cost, Highly Lambertian Reflector Composite For Improved LED Fixture Efficiency and Lifetime

    SciTech Connect

    Teather, Eric

    2013-02-15

    The overall objective of the program was to demonstrate a 98% or greater reflective, highly diffuse, low-cost composite material that significantly improves luminaire efficiency, is able to withstand 50,000 hours or greater luminaire operation under expected LED system thermal and environmental operating extremes and meets the cost targets required to be an effective commercial solution for the Solid State Lighting industry. This project met most of the goals defined and contributed to the understanding of high reflectance, white coatings. Research under this program increased the understanding of coatings development using particle size reduction techniques and preparation of coating solutions with a broad range of particle types. The research explored scale-up of coating systems and generated understanding of processing required for high volume manufacturing applications. The work demonstrated how coating formulation and application technique can translate to material durability and LED system lifetime. The research also demonstrated improvements in lighting efficiency to be gained using high reflectance white coatings.

  1. Salivary Cortisol Responses and Perceived Exertion during High Intensity and Low Intensity Bouts of Resistance Exercise

    PubMed Central

    McGuigan, Michael R.; Egan, Alison D.; Foster, Carl

    2004-01-01

    The purpose of this study was to measure the salivary cortisol response to different intensities of resistance exercise. In addition, we wanted to determine the reliability of the session rating of perceived exertion (RPE) scale to monitor resistance exercise intensity. Subjects (8 men, 9 women) completed 2 trials of acute resistance training bouts in a counterbalanced design. The high intensity resistance exercise protocol consisted of six, ten-repetition sets using 75% of one repetition maximum (RM) on a Smith machine squat and bench press exercise (12 sets total). The low intensity resistance exercise protocol consisted of three, ten-repetition sets at 30% of 1RM of the same exercises as the high intensity protocol. Both exercise bouts were performed with 2 minutes of rest between each exercise and sessions were repeated to test reliability of the measures. The order of the exercise bouts was randomized with least 72 hours between each session. Saliva samples were obtained immediately before, immediately after and 30 mins following each resistance exercise bout. RPE measures were obtained using Borg’s CR-10 scale following each set. Also, the session RPE for the entire exercise session was obtained 30 minutes following completion of the session. There was a significant 97% increase in the level of salivary cortisol immediately following the high intensity exercise session (P<0.05). There was also a significant difference in salivary cortisol of 145% between the low intensity and high intensity exercise session immediately post-exercise (P<0.05). The low intensity exercise did not result in any significant changes in cortisol levels. There was also a significant difference between the session RPE values for the different intensity levels (high intensity 7.1 vs. low intensity 1.9) (P<0.05). The intraclass correlation coefficient for the session RPE measure was 0.95. It was concluded that the session RPE method is a valid and reliable method of quantifying

  2. Light shield and cooling apparatus. [high intensity ultraviolet lamp

    NASA Technical Reports Server (NTRS)

    Meador, T. G., Jr. (Inventor)

    1974-01-01

    A light shield and cooling apparatus was developed for a high intensity ultraviolet lamp including water and high pressure air for cooling and additional apparatus for shielding the light and suppressing the high pressure air noise.

  3. Carrier capture efficiency in InGaN/GaN LEDs: Role of high temperature annealing

    SciTech Connect

    Vinattieri, A.; Batignani, F.; Bogani, F.; Meneghini, M.; Meneghesso, G.; Zanoni, E.; Zhu, D.; Humphreys, C. J.

    2014-02-21

    By means of time integrated (TI), time-resolved (TR) photoluminescence (PL) and PL excitation spectra, we investigate the role of an high temperature post-growth thermal annealing (TA) on a set of InGaN/GaN LED structures with different dislocation densities. We provide evidence of the nature of the radiative recombination from a wide distribution of non-interacting localised states and we show the beneficial effect of thermal annealing in reducing the contribution of non-radiative recombination in the well region.

  4. Study of high power white AC-LED based on the structure of composite bridge with SMD packaging

    NASA Astrophysics Data System (ADS)

    Wang, Zhibin; Gu, Yue; Xie, Shasha

    2010-10-01

    In this paper, a method of composite bridge structure packing with self-rectifier in the LED chips is introduced, based on the characteristics of PN junction of the high power LED. About dozens of low-power LED chips are pasted on the PCB boards which having good thermal conductivity in the form of bridge structure, regulating input voltage and current strength to make the LED chips at different bridge arms worked alternately by using of LED PN junction's own characteristics to achieve self-rectification. The copper cooling plates are sandwiched in the PCB boards to achieve for saving resource and improving brightness. During the work time, the LED flashes lights. Because of its feature of continuing light after power properties, the human eyes can not perceive the LED's flashing, their understanding on the light emitting is continuous.

  5. Aluminium plasma production at high laser intensity

    SciTech Connect

    Torrisi, L.; Cutroneo, M.

    2014-02-28

    Thick and thin films of Al targets were irradiated in vacuum with iodine laser at 1315 nm wavelength, 300 ps pulse duration at a maximum intensity of about 10{sup 16} W/cm{sup 2} by varying the pulse energy and focal position. The laser-generated plasma was monitored in forward and backward directions by using ion collectors, SiC detectors, Thomson parabola spectrometer, and X-ray streak camera. Ion emission shows maximum proton energy of about 4 MeV in self-focusing conditions and a maximum Al ion energy of about 50 MeV. An evaluation of the electric field driving ions in conditions of target normal sheath acceleration is given.

  6. A novel MOCVD reactor for growth of high-quality GaN-related LED layers

    NASA Astrophysics Data System (ADS)

    Hu, Shaolin; Liu, Sheng; Zhang, Zhi; Yan, Han; Gan, Zhiyin; Fang, Haisheng

    2015-04-01

    Gallium nitride (GaN), a direct bandgap semiconductor widely used in bright light-emitting diodes (LEDs), is mostly grown by metal-organic chemical vapor deposition (MOCVD) method. A good reactor design is critical for the production of high-quality GaN thin films. In this paper, we presented a novel buffered distributed spray (BDS) MOCVD reactor with vertical gas sprayers and horizontal gas inlets. Experiments based on a 36×2″ BDS reactor were conducted to examine influence of the process parameters, such as the operating pressure and the gas flow rate, on the growth efficiency and on the layer thickness uniformity. Transmission electron microscopy (TEM) and photoluminescence (PL) are further conducted to evaluate quality of the epitaxial layers and to check performance of the reactor. Results show that the proposed novel reactor is of high performance in growing high-quality thin films, including InGaN/GaN multiquantum wells (MQWs) structures.

  7. FLASH requirements for the high intensity radiated field electromagnetic environment

    NASA Astrophysics Data System (ADS)

    Murdock, John K.

    1995-05-01

    The worldwide proliferation of high intensity emitting sources and the more electric aircraft increase the intensity of the Electromagnetic Environment (EME) in which aircraft must operate. A FLASH program HIRF (High Intensity Radiated Field) EME requirement is derived to cover both commercial and military fixed and rotary wing aircraft. This requirement is derived from the radiated susceptibility requirement documents of both the FAA and U.S. military. Specific test data and analysis will show that we can meet this requirement.

  8. Terrain following of arbitrary surfaces using a high intensity LED proximity sensor

    SciTech Connect

    Baker, J.E.

    1992-01-01

    Many robotic operations, e.g., mapping, scanning, feature following, etc., require accurate surface following of arbitrary targets. This paper presents a versatile surface following and mapping system designed to promote hardware, software and application independence, modular development, and upward expandability. These goals are met by: a full, a priori specification of the hardware and software interfaces; a modular system architecture; and a hierarchical surface-data analysis method, permitting application specific tuning at each conceptual level of topological abstraction. This surface following system was fully designed and independently of any specific robotic host, then successfully integrated with and demonstrated on a completely a priori unknown, real-time robotic system. 7 refs.

  9. High-intensity beam collimation and targetry

    SciTech Connect

    Mokhov, N.V.; /Fermilab

    2006-11-01

    Principles, design criteria and realization of reliable collimation systems for the high-power accelerators and hadron colliders are described. Functionality of collimators as the key elements of the machine protection system are discussed along with the substantial progress on the crystal collimation front. The key issues are considered in design of high-power target systems and achieving their best performance. Simulation code requirements are presented.

  10. Charge Strippers of Heavy Ions for High Intensity Accelerators

    NASA Astrophysics Data System (ADS)

    Nolen, Jerry A.; Marti, Felix

    2014-02-01

    Charge strippers play a critical role in many high intensity heavy ion accelerators. Here we present some history of recent stripper technology development and indicate the capabilities and limitations of the various approaches. The properties of solid, gaseous, and liquid strippers are covered. In particular, the limitations of solid strippers for high intensity, high atomic number heavy ions and the unique features of helium gas and liquid lithium for high intensity applications are covered. The need for high quality simulation of stripper performance as important input for system optimization is explained and examples of the current simulation codes are given.

  11. Engineering Food Ingredients with High-Intensity Ultrasound

    NASA Astrophysics Data System (ADS)

    Weiss, Jochen; Kristbergsson, Kristberg; Kjartansson, Gunnar Thor

    The use of ultrasound in the food industry has increased in the last decades. Ultrasound has been used both to analyze food structure and composition at low ultrasonic intensities and high frequencies and to modify ingredients at high ultrasonic intensities and low frequencies. Application of the latter is referred to as high-intensity (power) ultrasonication and is generally carried out at frequencies of =0.1 MHz and ultrasonic intensities of 10-100 W cm-2. In the food industry, power ultrasonication has proved to be a highly effective food processing and preservation technology, and use of high-intensity ultrasound with or without heat may be used, for example, to denature enzymes, aid in the extraction of valuable compounds from plants and seeds, tenderize meat, and homogenize or disperse two-phase systems such as emulsions or suspensions (Mason et al., 1996).

  12. Dicing of high-power white LEDs in heat sinks with the water jet-guided laser

    NASA Astrophysics Data System (ADS)

    Mai, Tuan Anh; Housh, Roy; Brulé, Arnaud; Richerzhagen, Bernold

    2007-02-01

    High-brightness LEDs are compound semiconductor devices and distinguish themselves from conventional LEDs by their exceptional luminosity. Today they are increasingly used as light sources, replacing conventional incandescent and fluorescent lamp technologies. HB LEDs are difficult to manufacture, as they must be grown by sophisticated epitaxial growth techniques such as MOCVD. They are packaged like power semiconductors, using surface mount technology and thermal pads. After having been successfully applied to GaN scribing for side-emitting LEDs, the Laser MicroJet (R) is used today for cutting heat sinks of HB white LEDs. Due to the high-emitted light power, the generated heat must be dissipated through a heat sink. Materials typically employed are metals with high heat conductivity, notably CuW and molybdenum. Applying the Laser MicroJet (R) the achieved cutting quality in these metals is outstanding - smooth edges, no contamination, no burrs, no heat damage, no warping - all this at high speed.

  13. A compact high intensity cooler (CHIC)

    NASA Astrophysics Data System (ADS)

    Bland, T. J.; Niggemann, R. E.; Parekh, M. B.

    1983-07-01

    A unique heat exchanger has been developed with potential applications for cooling high power density electronics and perhaps high energy laser mirrors. The device was designed to absorb heat fluxes of approximately 50 w/sq cm (158,000 Btu/hr sq ft), with a low thermal resistance, a high surface temperature uniformity, and very low hydraulic pumping power. A stack of thin copper orifice plates and spacers was bonded together and arranged to provide liquid jet impingement heat transfer on successive plates. This configuration resulted in effective heat transfer coefficients, based on the prime surface, of about 85,000 w/sq m deg C (15,000 Btu/hr sq ft deg F) and 1.8 watts (0.002 hp) hydraulic power with liquid Freon 11 as coolant.

  14. Final focus system for high intensity beams

    SciTech Connect

    Henestroza, E.; Bieniosek, F.M.; Eylon, S.; Roy, P.K.; Yu, S.S.

    2003-05-01

    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. The NTX final focus system produces a converging beam at the entrance to the neutralized drift section where it focuses to a small spot. The final focus lattice consists of four pulsed quadrupole magnets. The main issues are the control of emittance growth due to high order fields from magnetic multipoles and image fields. We will present experimental results from NTX on beam envelope and phase space distributions, and compare these results with particle simulations using the particle-in-cell code WARP.

  15. Speckle-correlation imaging through highly scattering turbid media with LED illumination

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Dai, Weijia; Wu, Tengfei; Li, Huijuan; Wang, Lin

    2015-05-01

    We address an optical imaging method that allows imaging, which owing to the "memory-effect" for speckle correlations, through highly scattering turbid media with "Error Reduction - Hybid Input Ouput (ER-HIO)" algorithm. When light propagates through the opaque materials, such as white paint, paper or biological tissues, it will be scattered away due to the inhomogeneity of the refractive index. Multiple scattering of light in highly scattering media forms speckle field, which will greatly reduce the imaging depth and degrade the imaging quality. Some methods have been developed to solve this problem in recent years, including wavefront modulation method (WMM), transmission matrix method (TMM) and speckle correlations method (SCM). A novel approach is proposed to image through a highly scattering turbid medium, which combines speckle correlations method (SCM) with phase retrieval algorithm (PRA). Here, we show that, owing to the "optical memory effect" for speckle correlations, a single frame image of the speckle field, captured with a high performance detector, encodes sufficient information to image through highly scattering turbid media. Theoretical and experimental results show that, neither the light source, nor wave-front shaping is required in this method, and that the imaging can be easily realized here using just a simple optical system with the help of optical memory effect. Our method does not require coherent light source, which can be achieved with LED illumination, unlike previous approaches, and therefore is potentially suitable for more and more areas. Consequently, it will be beneficial to achieve imaging in currently inaccessible scenarios.

  16. An improved high intensity recycling helium-3 beam source

    SciTech Connect

    Hedgeland, H.; Kole, P. R.; Allison, W.; Ellis, J.; Jardine, A. P.

    2009-07-15

    We describe an improved high intensity, recycling, supersonic atomic beam source. Changes address several issues previously limiting performance and reliability of the apparatus, including the use of newly available vacuum pumps and modifications to the recycling system. We achieve a source intensity of 2.5x10{sup 19} atoms/s/sr, almost twice that previously achievable during recycling. Current limits on intensity are discussed.

  17. An improved high intensity recycling helium-3 beam source.

    PubMed

    Hedgeland, H; Kole, P R; Allison, W; Ellis, J; Jardine, A P

    2009-07-01

    We describe an improved high intensity, recycling, supersonic atomic beam source. Changes address several issues previously limiting performance and reliability of the apparatus, including the use of newly available vacuum pumps and modifications to the recycling system. We achieve a source intensity of 2.5 x 10(19) atoms/s/sr, almost twice that previously achievable during recycling. Current limits on intensity are discussed. PMID:19655995

  18. Leveraging the Power of Peer-Led Learning: Investigating Effects on STEM Performance in Urban High Schools

    ERIC Educational Resources Information Center

    Thomas, Ally S.; Bonner, Sarah M.; Everson, Howard T.; Somers, Jennifer A.

    2015-01-01

    The Peer Enabled Restructured Classroom (PERC) is an instructional innovation developed to address gaps in science, technology, engineering, and math (STEM) in urban high schools. The PERC model changes instruction from teacher led to peer led by bringing peer students into the classroom to lead small-group work. Our study sought to provide…

  19. High intensity anthropogenic sound damages fish ears

    NASA Astrophysics Data System (ADS)

    McCauley, Robert D.; Fewtrell, Jane; Popper, Arthur N.

    2003-01-01

    Marine petroleum exploration involves the repetitive use of high-energy noise sources, air-guns, that produce a short, sharp, low-frequency sound. Despite reports of behavioral responses of fishes and marine mammals to such noise, it is not known whether exposure to air-guns has the potential to damage the ears of aquatic vertebrates. It is shown here that the ears of fish exposed to an operating air-gun sustained extensive damage to their sensory epithelia that was apparent as ablated hair cells. The damage was regionally severe, with no evidence of repair or replacement of damaged sensory cells up to 58 days after air-gun exposure.

  20. Neutralized transport of high intensity beams

    SciTech Connect

    Henestroza, E.; Yu, S.S.; Eylon, S.; Roy, P.K.; Anders, A.; Sharp, W.; Efthimion, P.; Gilson, E.; Welch, D.; Rose, D.

    2003-05-01

    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. A converging ion beam at the exit of the final focus magnetic system is injected into a neutralized drift section. The neutralization is provided by a metal arc source and an RF plasma source. Effects of a ''plasma plug'', where electrons are extracted from a localized plasma in the upstream end of the drift section, and are then dragged along by the ion potential, as well as the ''volumetric plasma'', where neutralization is provided by the plasma laid down along the ion path, are both studied and their relative effects on the beam spot size are compared. Comparisons with 3-D PIC code predictions will also be presented.

  1. High precision digital control LED spot light source used to calibrate camera

    NASA Astrophysics Data System (ADS)

    Du, Boyu; Xu, Xiping; Liu, Yang

    2015-04-01

    This paper introduces a method of using LED point light source as the camera calibration light. According to the characteristics of the LED point light source, the constant current source is used to provide the necessary current and the illuminometer is used to measure the luminance of the LED point light source. The constant current source is controlled by ARM MCU and exchange data with the host computer though the mode of serial communications. The PC is used as the host computer, it adjust the current according to the luminance of the LED point light source until the luminance achieve the anticipated value. By experimental analysis, we found that the LED point light source can achieve the desired requirements as the calibration light source, and the accuracy is quite better that achieve the desired effect and it can adaptive control the luminance of LED well. The system is convenient and flexible, and its performance is stable and reliable.

  2. High-intensity drying processes: Impulse drying

    SciTech Connect

    Orloff, D.I.

    1989-05-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during manufacture of paper and similar web products. Impulse drying occurs when a wet paper web passes through a press nip where one of the rolls is heated to a very high temperature. Steam generated by contact with the hot roll expands and displaces water from the sheet in a very efficient manner. The energy required for water removal is much lower than that required for conventional evaporative drying. Tests have been completed that elucidate the unique displacement mechanism of water removal in the impulse drying process. A pilot roll press has been designed, installed and used to examine impulse drying under conditions that simulate commercial press conditions. The results of this earlier work have been reported in three previous reports. During this report period October, 1987 to September, 1988, the pilot press was equipped with a second impulse drying roll to facilitate studies of surface uniformity in impulse dried paper. Studies have also been completed which examine the origins of sheet delamination that has been been encountered during impulse drying of certain heavyweight paper grades, and which investigate approaches to prevent delamination in these grades. Finally, an experimental plan has been formalized to examine impulse drying of lightweight grades which are candidates for early commercialization. 7 refs., 30 figs., 3 tabs.

  3. High-intensity drying processes: Impulse drying

    SciTech Connect

    Orloff, D.I.

    1990-09-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during the manufacture of paper and similar web products. Impulse drying occurs when a wet paper web passes through a press nip in which one of the rolls is heated to a high temperature. A steam layer adjacent to the heated surface grows and displaces water from the sheet in a very efficient manner. The energy required for water removal is very much less than that required for conventional evaporative drying. Hence, it has been projected that wide commercialization of impulse drying would result in at least a 10% industry-wide energy saving. This report covers work completed between October, 1988 and September, 1989. During this period, pilot press trails demonstrated that newsprint as well as linerboard experience delamination. Hence, the major focus of the research was the resolution of the delamination problem. In order to document potential process improvements, measurement methods were developed to quantify sheet delamination. Using these methods, low thermal diffusivity ceramic roll surfaces were shown to extend the range of impulse drying operating conditions while avoiding sheet delamination. As compared to steel surfaces, ceramics were found to provide significantly higher water volume without inducing sheet delamination. 46 figs., 4 tabs.

  4. Light-intensity modulator withstands high heat fluxes

    NASA Technical Reports Server (NTRS)

    Maples, H. G.; Strass, H. K.

    1966-01-01

    Mechanism modulates and controls the intensity of luminous radiation in light beams associated with high-intensity heat flux. This modulator incorporates two fluid-cooled, externally grooved, contracting metal cylinders which when rotated about their longitudinal axes present a circular aperture of varying size depending on the degree of rotation.

  5. High intensity, argon ion laser-jet photochemistry

    NASA Astrophysics Data System (ADS)

    Wilson, R. Marshall; Schnapp, Karlyn A.; Hannemann, Klaus; Ho, Douglas M.; Memarian, Hamid R.; Azadnia, Ardeshir; Pinhas, Allan R.; Figley, Timothy M.

    A new technique for the study of high intensity solution photochemistry has been developed. With this laser-jet technique, a high velocity microjet is irradiated with the focussed output of an argon ion laser. Under these extremely high intensity conditions, photochemically generated transient species with suitable absorption properties are excited further and produce relatively large amounts of photoproducts which are not observed under low intensity conditions. The application of this laser-jet technique in the study of the photochemistry of radicals, biradicals, photoenols and the higher excited states of carbonyl and polycyclic aromatic compounds is described.

  6. ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS.

    SciTech Connect

    WEI,J.; MACEK,R.J.

    2002-04-14

    One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures.

  7. High Intensity heavy ion Accelerator Facility (HIAF) in China

    NASA Astrophysics Data System (ADS)

    Yang, J. C.; Xia, J. W.; Xiao, G. Q.; Xu, H. S.; Zhao, H. W.; Zhou, X. H.; Ma, X. W.; He, Y.; Ma, L. Z.; Gao, D. Q.; Meng, J.; Xu, Z.; Mao, R. S.; Zhang, W.; Wang, Y. Y.; Sun, L. T.; Yuan, Y. J.; Yuan, P.; Zhan, W. L.; Shi, J.; Chai, W. P.; Yin, D. Y.; Li, P.; Li, J.; Mao, L. J.; Zhang, J. Q.; Sheng, L. N.

    2013-12-01

    HIAF (High Intensity heavy ion Accelerator Facility), a new facility planned in China for heavy ion related researches, consists of two ion sources, a high intensity Heavy Ion Superconducting Linac (HISCL), a 45 Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage ring system. The key features of HIAF are unprecedented high pulse beam intensity and versatile operation mode. The HIAF project aims to expand nuclear and related researches into presently unreachable region and give scientists possibilities to conduct cutting-edge researches in these fields. The general description of the facility is given in this article with a focus on the accelerator design.

  8. Repeated high-intensity exercise in professional rugby union.

    PubMed

    Austin, Damien; Gabbett, Tim; Jenkins, David

    2011-07-01

    The aim of the present study was to describe the frequency, duration, and nature of repeated high-intensity exercise in Super 14 rugby union. Time-motion analysis was used during seven competition matches over the 2008 and 2009 Super 14 seasons; five players from each of four positional groups (front row forwards, back row forwards, inside backs, and outside backs) were assessed (20 players in total). A repeated high-intensity exercise bout was considered to involve three or more sprints, and/or tackles and/or scrum/ruck/maul activities within 21 s during the same passage of play. The range of repeated high-intensity exercise bouts for each group in a match was as follows: 11-18 for front row forwards, 11-21 for back row forwards, 13-18 for inside backs, and 2-11 for outside backs. The durations of the most intense repeated high-intensity exercise bouts for each position ranged from 53 s to 165 s and the minimum recovery periods between repeated high-intensity exercise bouts ranged from 25 s for the back row forwards to 64 s for the front row forwards. The present results show that repeated high-intensity exercise bouts vary in duration and activities relative to position but all players in a game will average at least 10 changes in activity in the most demanding bouts and complete at least one tackle and two sprints. The most intense periods of activity are likely to last as long as 120 s and as little as 25 s recovery may separate consecutive repeated high-intensity exercise bouts. The present findings can be used by coaches to prepare their players for the most demanding passages of play likely to be experienced in elite rugby union. PMID:21756130

  9. Space Station Live: High-Intensity Exercise in Space

    NASA Video Gallery

    NASA Public Affairs Officer Lori Meggs talks with SPRINT Principal Investigator Lori Ploutz-Snyder to learn more about this high-intensity exercise research taking place aboard the International Sp...

  10. Fundamental Studies and Development of III-N Visible LEDs for High-Power Solid-State Lighting Applications

    SciTech Connect

    Dupuis, Russell

    2012-02-29

    The goal of this program is to understand in a fundamental way the impact of strain, defects, polarization, and Stokes loss in relation to unique device structures upon the internal quantum efficiency (IQE) and efficiency droop (ED) of III-nitride (III-N) light-emitting diodes (LEDs) and to employ this understanding in the design and growth of high-efficiency LEDs capable of highly-reliable, high-current, high-power operation. This knowledge will be the basis for our advanced device epitaxial designs that lead to improved device performance. The primary approach we will employ is to exploit new scientific and engineering knowledge generated through the application of a set of unique advanced growth and characterization tools to develop new concepts in strain-, polarization-, and carrier dynamics-engineered and low-defect materials and device designs having reduced dislocations and improved carrier collection followed by efficient photon generation. We studied the effects of crystalline defect, polarizations, hole transport, electron-spillover, electron blocking layer, underlying layer below the multiplequantum- well active region, and developed high-efficiency and efficiency-droop-mitigated blue LEDs with a new LED epitaxial structures. We believe new LEDs developed in this program will make a breakthrough in the development of high-efficiency high-power visible III-N LEDs from violet to green spectral region.

  11. High brightness LEDs for general lighting applications Using the new ThinGaNTM-Technology

    NASA Astrophysics Data System (ADS)

    Haerle, V.; Hahn, B.; Kaiser, S.; Weimar, A.; Bader, S.; Eberhard, F.; Plössl, A.; Eisert, D.

    2004-09-01

    During the last years GaN-technology has proven to fulfill the requirements of solid state lighting. Lighting requirements are mainly driven by brightness, operation voltage and lifetime. Brigthness is determined by internal efficiency as well as extraction efficiency whereas the ohmic losses determining the operating voltage are dominated by series resistance and contact resistance. Both, brightness and voltage, strongly depend on the device structure as well as the chip design. SiC based [1, 2] as well as Sapphire based LEDs [3] have proven their capability for high brightness devices, still suffering from various compromises such as cost, ESD-stability, high series resistance etc.Recently OSRAM-OS has demonstrated its newly developed product line based on the so called ThinGaNTM technology, a true thinfilm approach that overcomes most of the compromises mentioned. The technology allows highest brightness levels at lowest operating voltage, is scalable and supports all wavelengths. The devices act as true surface emitters with a lambertian emission pattern.

  12. Generation of intense high-order vortex harmonics.

    PubMed

    Zhang, Xiaomei; Shen, Baifei; Shi, Yin; Wang, Xiaofeng; Zhang, Lingang; Wang, Wenpeng; Xu, Jiancai; Yi, Longqiong; Xu, Zhizhan

    2015-05-01

    This Letter presents for the first time a scheme to generate intense high-order optical vortices that carry orbital angular momentum in the extreme ultraviolet region based on relativistic harmonics from the surface of a solid target. In the three-dimensional particle-in-cell simulation, the high-order harmonics of the high-order vortex mode is generated in both reflected and transmitted light beams when a linearly polarized Laguerre-Gaussian laser pulse impinges on a solid foil. The azimuthal mode of the harmonics scales with its order. The intensity of the high-order vortex harmonics is close to the relativistic region, with the pulse duration down to attosecond scale. The obtained intense vortex beam possesses the combined properties of fine transversal structure due to the high-order mode and the fine longitudinal structure due to the short wavelength of the high-order harmonics. In addition to the application in high-resolution detection in both spatial and temporal scales, it also presents new opportunities in the intense vortex required fields, such as the inner shell ionization process and high energy twisted photons generation by Thomson scattering of such an intense vortex beam off relativistic electrons. PMID:25978234

  13. Fabrication of LED lighting goggle for surgical operation and approach toward high-color rendering performance

    NASA Astrophysics Data System (ADS)

    Kawakami, Yoichi; Shimada, Junichi; Fujita, Shigeo

    2001-12-01

    The first internal shunt operation in the left forearm has successfully been performed using the surgical lighting goggle composed of InGaN-yttrium aluminum garnet (YAG)-based white light emitting diode(LED) arrays. This system supplies a total luminous flux of about 200 lumen for several hours by driving with rechargeable Li-ion batteries. Further increase in luminous flux can be achieved by both the progress of emission efficiency of white LEDs and the development of dense packaging technique of LED chips. Moreover, the color rendering properties of white LEDs are inferior to the standard illuminant especially in violet, green and red spectral range. In this paper, several device structures are proposed for achieving power lighting and for higher color rendering properties. The key technology for power lighting is how to radiate the heat out of LED chips, and that for higher color rendering is how to add desired illumination-spectral-components to LEDs according to the application fields.

  14. Measurements of acoustic pressure at high amplitudes and intensities

    NASA Astrophysics Data System (ADS)

    Crum, L. A.; Bailey, M. R.; Kaczkowski, P.; McAteer, J. A.; Pishchalnikov, Y. A.; Sapozhnikov, O. A.

    2004-01-01

    In our research group, we desire measurements of the large pressure amplitudes generated by the shock waves used in shock wave lithotripsy (SWL) and the large acoustic intensities used in High Intensity Focused Ultrasound (HIFU). Conventional piezoelectric or PVDF hydrophones can not be used for such measurements as they are damaged either by cavitation, in SWL applications, or heat, in HIFU applications. In order to circumvent these difficulties, we have utilized optical fiber hydrophones in SWL that do not cavitate, and small glass probes and a scattering technique for measurements of large HIFU intensities. Descriptions of these techniques will be given as well as some typical data.

  15. Review of High-intensity Interval Training in Cardiac Rehabilitation.

    PubMed

    Ito, Shigenori; Mizoguchi, Tatsuya; Saeki, Tomoaki

    2016-01-01

    For the secondary prevention of cardiovascular disease, comprehensive cardiac rehabilitation is required. This involves optimal medical therapy, education on nutrition and exercise therapy, and smoking cessation. Of these, efficient exercise therapy is a key factor. A highly effective training protocol is therefore warranted, which requires a high rate of compliance. Although moderate-intensity continuous training has been the main training regimen recommended in cardiac rehabilitation guidelines, high-intensity interval training has been reported to be more effective in the clinical and experimental setting from the standpoint of peak oxygen uptake and central and peripheral adaptations. In this review, we illustrate the scientific evidence for high-intensity interval training. We then verify this evidence and discuss its significance and the remaining issues. PMID:27580530

  16. H- Ion Sources for High Intensity Proton Drivers

    SciTech Connect

    Johnson, Rolland Paul; Dudnikov, Vadim

    2015-02-20

    Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H+ and H- ion generation around 3 to 5 mA/cm2 per kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H- ion production efficiency, reliability and availability for pulsed operation as used in the ORNL Spallation Neutron Source . At low RF power, the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm2 per kW of RF power at 13.56 MHz. Initial cesiation of the SPS was performed by heating cesium chromate cartridges by discharge as was done in the very first versions of the SPS. A small oven to decompose cesium compounds and alloys was developed and tested. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power 1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with 4 kW RF power in the plasma and 250 Gauss longitudinal magnetic field. The ratio of electron current to negative ion current was improved from 30 to 2. Stable generation of H- beam without intensity degradation was demonstrated in the aluminum nitride (AlN) discharge chamber for 32 days at high discharge power in an RF SPS with an external antenna. Some modifications were made to improve the cooling and cesiation stability. The extracted collector current can be increased significantly by optimizing the longitudinal magnetic field in the discharge chamber. While this project demonstrated the advantages of the pulsed version of the SA RF SPS as an upgrade to the ORNL Spallation Neutron Source, it led to a possibility for upgrades to CW machines like the many cyclotrons used for commercial applications. Four appendices contain important details of the work carried out under this grant.

  17. High linearly polarized light emission from GaN-based LED with patterned dielectric/metal structures

    NASA Astrophysics Data System (ADS)

    Wang, Miao; Cao, Bing; Xu, Fuyang; Hu, Jingpei; Wang, Jianfeng; Xu, Ke; Wang, Chinhua

    2015-07-01

    We proposed and demonstrated an integrated high linearly polarized InGaN/GaN green LED grown on (0001) oriented sapphire with a structure of combined dielectric/metal wire grids (CDMWG). Both theoretical and experimental results show that the CDMWG can effectively loosen the requirement on the dimension of the grating, and the introduction of a low-refractive dielectric layer can further enhance both TMT and ER significantly for the GaN-type LED. An InGaN/ GaN green LED with an integrated CDMWG of 220 nm period has been fabricated, and a measured extinction ratio(ER) of higher than 20 dB and TMT of 65% within an angle of +/-40° is obtained directly from a InGaN/GaN LED.

  18. Acute plasma volume change with high-intensity sprint exercise.

    PubMed

    Bloomer, Richard J; Farney, Tyler M

    2013-10-01

    When exercise is of long duration or of moderate to high intensity, a decrease in plasma volume can be observed. This has been noted for both aerobic and resistance exercise, but few data are available with regard to high-intensity sprint exercise. We measured plasma volume before and after 3 different bouts of acute exercise, of varying intensity, and/or duration. On different days, men (n = 12; 21-35 years) performed aerobic cycle exercise (60 minutes at 70% heart rate reserve) and 2 different bouts of cycle sprints (five 60-second sprints at 100% maximum wattage obtained during graded exercise testing (GXT) and ten 15-second sprints at 200% maximum wattage obtained during GXT). Blood was collected before and 0, 30, and 60 minutes postexercise and analyzed for hematocrit and hemoglobin and plasma volume was calculated. Plasma volume decreased significantly for all exercise bouts (p < 0.05), with the greatest decrease noted 0 minute postexercise for both sprint bouts (∼19%) compared with aerobic exercise bouts (∼11%). By 30 minutes postexercise, plasma volume approached pre-exercise values. We conclude that acute bouts of exercise, in particular high-intensity sprint exercise, significantly decrease plasma volume during the immediate postexercise period. It is unknown what, if any negative implications these transient changes may have on exercise performance. Strength and conditioning professionals may aim to rehydrate athletes appropriately after high-intensity exercise bouts. PMID:23302756

  19. High color rendering white light-emitting-diode illuminator using the red-emitting Eu(2+)-activated CaZnOS phosphors excited by blue LED.

    PubMed

    Kuo, Te-Wen; Liu, Wei-Ren; Chen, Teng-Ming

    2010-04-12

    A red phosphor CaZnOS:Eu(2+) was synthesized by solid state reaction and has been evaluated as a candidate for white LEDs. For this material, the XRD, PL, PL excitation (PLE) and diffuse reflection spectra have also been investigated. CaZnOS:Eu(2+) reveals a broad absorption band and good color purity. By utilizing a mixture of red-emitting CaZnOS:Eu(2+), green-emitting (Ba,Sr)(2)SiO(4):Eu(2+) and yellow-emitting Y(3)Al(5)O(12):Ce(3+) as light converters, an intense white InGaN-based blue-LED (~460 nm) was fabricated to exhibit a high color-rendering index Ra of 85 at a correlated color temperature of 4870 K. Based on the results, we are currently evaluating the potential application of CaZnOS:Eu(2+) as a red-emitting blue-chip convertible phosphor. PMID:20588664

  20. Highly energy-efficient agricultural lighting by B+R LEDs with beam shaping using micro-lens diffuser

    NASA Astrophysics Data System (ADS)

    Lee, Xuan-Hao; Chang, Yu-Yu; Sun, Ching-Cherng

    2013-03-01

    This paper presents a high-performance LED agricultural luminaire that uses a beam-shaping diffuser to achieve high optical efficiency and energy saving. The agricultural luminaire performs an optical efficiency as high as 84.2%. The beam shaping effect also obtains irradiance uniformity of 1/2.56 and excellent spatial color uniformity. The enhancement ratio of optical utilization factor in the proposed agricultural luminaire is 360% in comparison with traditional lighting. Under the designed case, the total utilization factor, including optical utilization factor and spectral utilization factor, of the B+R LED lamp can save 86.1% of power consumption in comparison with compact fluorescent bulbs.

  1. Acoustic intensity near a high-powered military jet aircraft.

    PubMed

    Stout, Trevor A; Gee, Kent L; Neilsen, Tracianne B; Wall, Alan T; James, Michael M

    2015-07-01

    The spatial variation in vector acoustic intensity has been calculated between 100 and 3000 Hz near a high-performance military aircraft. With one engine of a tethered F-22A Raptor operating at military power, a tetrahedral intensity probe was moved to 27 locations in the geometric near and mid-fields to obtain the frequency-dependent intensity vector field. The angles of the maximum intensity region rotate from aft to sideline with increasing frequency, becoming less directional above 800 Hz. Between 100 and 400 Hz, which are principal radiation frequencies, the ray-traced dominant source region rapidly contracts and moves upstream, approaching nearly constant behavior by 1000 Hz. PMID:26233049

  2. Beam diagnostics at high-intensity storage rings

    SciTech Connect

    Plum, M.

    1993-11-01

    Beam diagnostics at high-intensity facilities feature their own special set of problems and characteristics. Issues peculiar to high-intensity storage rings include beam loss, beam halos, extraction efficiency, beam in the gap, clearing electrodes, and beam-profile measurement. The Los Alamos Proton Storage Ring (PSR) is a nice example of a high-intensity storage ring. The author discusses in some detail three diagnostic systems currently in use at the PSR: the beam-loss-monitor system, the electron-clearing system, and the beam-in-the-gap monitor. Much of the discussion is inspired by the problems that were encountered and the useful things learned while commissioning and developing the PSR. Another inspiration is the work on the next-generation neutron-spallation source, also known as the National Center for Neutron Research (NCNR).

  3. Beam diagnostics at high-intensity storage rings

    SciTech Connect

    Plum, M. )

    1994-10-10

    Beam diagnostics at high-intensity facilities feature their own special set of problems and characteristics, issues peculiar to high-intensity storage rings include beam loss, beam halos, extraction efficiency, beam in the gap, clearing electrodes, and beam-profile measurement. The Los Alamos Proton Storage Ring (PSR) is a nice example of a high-intensity storage ring. I will discuss in some detail three diagnostic systems currently in use at the PSR: the beam-loss-monitor system, the electron-clearing system, and the beam-in-the-gap monitor. Much of our discussion is inspired by the problems we have encountered and the useful things we have learned while commissioning and developing the PSR. Another inspiration is our work on the next-generation neutron-spallation source, also known as the National Center for Neutron Research (NCNR).

  4. High-resolution electroluminescent imaging of pressure distribution using a piezoelectric nanowire LED array

    NASA Astrophysics Data System (ADS)

    Pan, Caofeng; Dong, Lin; Zhu, Guang; Niu, Simiao; Yu, Ruomeng; Yang, Qing; Liu, Ying; Wang, Zhong Lin

    2013-09-01

    Emulation of the sensation of touch through high-resolution electronic means could become important in future generations of robotics and human-machine interfaces. Here, we demonstrate that a nanowire light-emitting diode-based pressure sensor array can map two-dimensional distributions of strain with an unprecedented spatial resolution of 2.7 µm, corresponding to a pixel density of 6,350 dpi. Each pixel is composed of a single n-ZnO nanowire/p-GaN light-emitting diode, the emission intensity of which depends on the local strain owing to the piezo-phototronic effect. A pressure map can be created by reading out, in parallel, the electroluminescent signal from all of the pixels with a time resolution of 90 ms. The device may represent a major step towards the digital imaging of mechanical signals by optical means, with potential applications in artificial skin, touchpad technology, personalized signatures, bio-imaging and optical microelectromechanical systems.

  5. Development of a High Irradiance LED Configuration for Small Field of View Motion Estimation of Fertilizer Particles

    PubMed Central

    Cool, Simon; Pieters, Jan G.; Mertens, Koen C.; Mora, Sergio; Cointault, Frédéric; Dubois, Julien; van de Gucht, Tim; Vangeyte, Jürgen

    2015-01-01

    Better characterization of the fertilizer spreading process, especially the fertilizer pattern distribution on the ground, requires an accurate measurement of individual particle properties and dynamics. Both 2D and 3D high speed imaging techniques have been developed for this purpose. To maximize the accuracy of the predictions, a specific illumination level is required. This paper describes the development of a high irradiance LED system for high speed motion estimation of fertilizer particles. A spectral sensitivity factor was used to select the optimal LED in relation to the used camera from a range of commercially available high power LEDs. A multiple objective genetic algorithm was used to find the optimal configuration of LEDs resulting in the most homogeneous irradiance in the target area. Simulations were carried out for different lenses and number of LEDs. The chosen configuration resulted in an average irradiance level of 452 W/m2 with coefficient of variation less than 2%. The algorithm proved superior and more flexible to other approaches reported in the literature and can be used for various other applications. PMID:26569261

  6. Development of a High Irradiance LED Configuration for Small Field of View Motion Estimation of Fertilizer Particles.

    PubMed

    Cool, Simon; Pieters, Jan G; Mertens, Koen C; Mora, Sergio; Cointault, Frédéric; Dubois, Julien; van de Gucht, Tim; Vangeyte, Jürgen

    2015-01-01

    Better characterization of the fertilizer spreading process, especially the fertilizer pattern distribution on the ground, requires an accurate measurement of individual particle properties and dynamics. Both 2D and 3D high speed imaging techniques have been developed for this purpose. To maximize the accuracy of the predictions, a specific illumination level is required. This paper describes the development of a high irradiance LED system for high speed motion estimation of fertilizer particles. A spectral sensitivity factor was used to select the optimal LED in relation to the used camera from a range of commercially available high power LEDs. A multiple objective genetic algorithm was used to find the optimal configuration of LEDs resulting in the most homogeneous irradiance in the target area. Simulations were carried out for different lenses and number of LEDs. The chosen configuration resulted in an average irradiance level of 452 W/m² with coefficient of variation less than 2%. The algorithm proved superior and more flexible to other approaches reported in the literature and can be used for various other applications. PMID:26569261

  7. A Portable, Low-Cost, LED Fluorimeter for Middle School, High School, and Undergraduate Chemistry Labs

    ERIC Educational Resources Information Center

    Wigton, Benjamin T.; Chohan, Balwant S.; McDonald, Cole; Johnson, Matt; Schunk, Doug; Kreuter, Rod; Sykes, Dan

    2011-01-01

    A low-cost portable fluorimeter was constructed using a 360 nm LED for excitation and a silicon photodiode for detection. The instrument is simple to operate and has been used to investigate fluorescent whitening agents extracted from various brands of paper, to determine the linear range and limit of detection of quinine in various commercial…

  8. Stability of glass versus plastics for transmissive high-power LED optics

    NASA Astrophysics Data System (ADS)

    Paßlick, C.; Hellwig, A.; Geyer, U.; Heßling, T.; Hübner, M. C.

    2014-09-01

    In the past, the major part of transmissive LED optics was made from injection molded polymers like PMMA or PC. Recent LED developments now show constantly increasing levels of luminous flux and energy densities, which restrict the usability of such polymer optics due to their limitations in thermal stability. Thermal simulations have shown that light guiding/mixing structures (rods) made from polymer materials can easily reach temperatures above their melting point due to the absorption characteristics. However, there is a great demand for such light rods from the automotive and entertainment industry and thus glass is becoming increasingly important as an optical material. Glass has typical transformation temperatures of hundreds of degrees Celsius and therefore withstands the conditions seen with LED without any problems. Square-shaped glass light guides show temperature advantages over round light rods, which are known for being able to produce caustics inside the material causing absorption and temperature hot spots, respectively. This paper presents some comparative thermal simulations by means of the Finite Element Method for a light conductor as an example and gives corresponding assistance for an appropriate material and light guide shape selection for highpower LED optics.

  9. Light-intensity and high-intensity interval training improve cardiometabolic health in rats.

    PubMed

    Batacan, Romeo B; Duncan, Mitch J; Dalbo, Vincent J; Connolly, Kylie J; Fenning, Andrew S

    2016-09-01

    Physical activity has the potential to reduce cardiometabolic risk factors but evaluation of different intensities of physical activity and the mechanisms behind their health effects still need to be fully established. This study examined the effects of sedentary behaviour, light-intensity training, and high-intensity interval training on biometric indices, glucose and lipid metabolism, inflammatory and oxidative stress markers, and vascular and cardiac function in adult rats. Rats (12 weeks old) were randomly assigned to 1 of 4 groups: control (CTL; no exercise), sedentary (SED; no exercise and housed in small cages to reduce activity), light-intensity trained (LIT; four 30-min exercise bouts/day at 8 m/min separated by 2-h rest period, 5 days/week), and high-intensity interval trained (HIIT, four 2.5-min work bouts/day at 50 m/min separated by 3-min rest periods, 5 days/week). After 12 weeks of intervention, SED had greater visceral fat accumulation (p < 0.01) and slower cardiac conduction (p = 0.04) compared with the CTL group. LIT and HIIT demonstrated beneficial changes in body weight, visceral and epididymal fat weight, glucose regulation, low-density lipoprotein cholesterol, total cholesterol, and mesenteric vessel contractile response compared with the CTL group (p < 0.05). LIT had significant improvements in insulin sensitivity and cardiac conduction compared with the CTL and SED groups whilst HIIT had significant improvements in systolic blood pressure and endothelium-independent vasodilation to aorta and mesenteric artery compared with the CTL group (p < 0.05). LIT and HIIT induce health benefits by improving traditional cardiometabolic risk factors. LIT improves cardiac health while HIIT promotes improvements in vascular health. PMID:27523646

  10. High Intensity Particle Physics at PW-class laser facilities

    NASA Astrophysics Data System (ADS)

    Bulanov, Stepan; Schroeder, Carl; Esarey, Eric; Esirkepov, Timur; Kando, Masaki; Rosanov, Nikolay; Korn, Georg; Bulanov, Sergey V.; Leemans, Wim P.

    2015-11-01

    The processes typical for high intensity particle physics, i.e., the interactions of charged particles with strong electromagnetic fields, have attracted considerable interest recently. Some of these processes, previously believed to be of theoretical interest only, are now becoming experimentally accessible. High intensity electromagnetic (EM) fields significantly modify the interactions of particles and EM fields, giving rise to the phenomena that are not encountered either in classical or perturbative quantum theory of these interactions. One of such phenomena is the radiation reaction, which radically influences the electron motion in an electromagnetic standing wave formed by two super-intense counter-propagating laser pulses. Depending on the laser intensity and wavelength, either classical or quantum mode of radiation reaction prevail, or both are strong. When radiation reaction dominates, electron motion evolves to limit cycles and strange attractors. This creates a new framework for high energy physics experiments on an interaction of energetic charged particle beams and colliding super-intense laser pulses. Work supported by U.S. DOE under Contract No. DE-AC02-05CH11231.

  11. Ion source and injection line for high intensity medical cyclotron

    SciTech Connect

    Jia, XianLu Guan, Fengping; Yao, Hongjuan; Zhang, TianJue; Yang, Jianjun; Song, Guofang; Ge, Tao; Qin, Jiuchang

    2014-02-15

    A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). An injection system based on the external H− ion source was used on CYCIAE-14 so as to provide high intensity beam, while most positron emission tomography cyclotrons adopt internal ion source. A beam intensity of 100 μA/14 MeV was extracted from the cyclotron with a small multi-cusp H− ion source (CIAE-CH-I type) and a short injection line, which the H− ion source of 3 mA/25 keV H− beam with emittance of 0.3π mm mrad and the injection line of with only 1.2 m from the extraction of ion source to the medial plane of the cyclotron. To increase the extracted beam intensity of the cyclotron, a new ion source (CIAE-CH-II type) of 9.1 mA was used, with maximum of 500 μA was achieved from the cyclotron. The design and test results of the ion source and injection line optimized for high intensity acceleration will be given in this paper.

  12. Validation of the Amsterdam Dynamic Facial Expression Set – Bath Intensity Variations (ADFES-BIV): A Set of Videos Expressing Low, Intermediate, and High Intensity Emotions

    PubMed Central

    Wingenbach, Tanja S. H.

    2016-01-01

    Most of the existing sets of facial expressions of emotion contain static photographs. While increasing demand for stimuli with enhanced ecological validity in facial emotion recognition research has led to the development of video stimuli, these typically involve full-blown (apex) expressions. However, variations of intensity in emotional facial expressions occur in real life social interactions, with low intensity expressions of emotions frequently occurring. The current study therefore developed and validated a set of video stimuli portraying three levels of intensity of emotional expressions, from low to high intensity. The videos were adapted from the Amsterdam Dynamic Facial Expression Set (ADFES) and termed the Bath Intensity Variations (ADFES-BIV). A healthy sample of 92 people recruited from the University of Bath community (41 male, 51 female) completed a facial emotion recognition task including expressions of 6 basic emotions (anger, happiness, disgust, fear, surprise, sadness) and 3 complex emotions (contempt, embarrassment, pride) that were expressed at three different intensities of expression and neutral. Accuracy scores (raw and unbiased (Hu) hit rates) were calculated, as well as response times. Accuracy rates above chance level of responding were found for all emotion categories, producing an overall raw hit rate of 69% for the ADFES-BIV. The three intensity levels were validated as distinct categories, with higher accuracies and faster responses to high intensity expressions than intermediate intensity expressions, which had higher accuracies and faster responses than low intensity expressions. To further validate the intensities, a second study with standardised display times was conducted replicating this pattern. The ADFES-BIV has greater ecological validity than many other emotion stimulus sets and allows for versatile applications in emotion research. It can be retrieved free of charge for research purposes from the corresponding author

  13. Validation of the Amsterdam Dynamic Facial Expression Set--Bath Intensity Variations (ADFES-BIV): A Set of Videos Expressing Low, Intermediate, and High Intensity Emotions.

    PubMed

    Wingenbach, Tanja S H; Ashwin, Chris; Brosnan, Mark

    2016-01-01

    Most of the existing sets of facial expressions of emotion contain static photographs. While increasing demand for stimuli with enhanced ecological validity in facial emotion recognition research has led to the development of video stimuli, these typically involve full-blown (apex) expressions. However, variations of intensity in emotional facial expressions occur in real life social interactions, with low intensity expressions of emotions frequently occurring. The current study therefore developed and validated a set of video stimuli portraying three levels of intensity of emotional expressions, from low to high intensity. The videos were adapted from the Amsterdam Dynamic Facial Expression Set (ADFES) and termed the Bath Intensity Variations (ADFES-BIV). A healthy sample of 92 people recruited from the University of Bath community (41 male, 51 female) completed a facial emotion recognition task including expressions of 6 basic emotions (anger, happiness, disgust, fear, surprise, sadness) and 3 complex emotions (contempt, embarrassment, pride) that were expressed at three different intensities of expression and neutral. Accuracy scores (raw and unbiased (Hu) hit rates) were calculated, as well as response times. Accuracy rates above chance level of responding were found for all emotion categories, producing an overall raw hit rate of 69% for the ADFES-BIV. The three intensity levels were validated as distinct categories, with higher accuracies and faster responses to high intensity expressions than intermediate intensity expressions, which had higher accuracies and faster responses than low intensity expressions. To further validate the intensities, a second study with standardised display times was conducted replicating this pattern. The ADFES-BIV has greater ecological validity than many other emotion stimulus sets and allows for versatile applications in emotion research. It can be retrieved free of charge for research purposes from the corresponding author

  14. Clinical applications of high-intensity focused ultrasound.

    PubMed

    She, W H; Cheung, T T; Jenkins, C R; Irwin, M G

    2016-08-01

    Ultrasound has been developed for therapeutic use in addition to its diagnostic ability. The use of focused ultrasound energy can offer a non-invasive method for tissue ablation, and can therefore be used to treat various solid tumours. High-intensity focused ultrasound is being increasingly used in the treatment of both primary and metastatic tumours as these can be precisely located for ablation. It has been shown to be particularly useful in the treatment of uterine fibroids, and various solid tumours including those of the pancreas and liver. High-intensity focused ultrasound is a valid treatment option for liver tumours in patients with significant medical co-morbidity who are at high risk for surgery or who have relatively poor liver function that may preclude hepatectomy. It has also been used as a form of bridging therapy while patients awaiting cadaveric donor liver transplantation. In this article, we outline the principles of high-intensity focused ultrasound and its clinical applications, including the management protocol development in the treatment of hepatocellular carcinoma in Hong Kong by performing a search on MEDLINE (OVID), EMBASE, and PubMed. The search of these databases ranged from the date of their establishment until December 2015. The search terms used were: high-intensity focused ultrasound, ultrasound, magnetic resonance imaging, liver tumour, hepatocellular carcinoma, pancreas, renal cell carcinoma, prostate cancer, breast cancer, fibroids, bone tumour, atrial fibrillation, glaucoma, Parkinson's disease, essential tremor, and neuropathic pain. PMID:27380753

  15. Thomson scattering in high-intensity chirped laser pulses

    NASA Astrophysics Data System (ADS)

    Holkundkar, Amol R.; Harvey, Chris; Marklund, Mattias

    2015-10-01

    We consider the Thomson scattering of an electron in an ultra-intense laser pulse. It is well known that at high laser intensities, the frequency and brilliance of the emitted radiation will be greatly reduced due to the electron losing energy before it reaches the peak field. In this work, we investigate the use of a small frequency chirp in the laser pulse in order to mitigate this effect of radiation reaction. It is found that the introduction of a negative chirp means the electron enters a high frequency region of the field while it still has a large proportion of its original energy. This results in a significant enhancement of the frequency and intensity of the emitted radiation as compared to the case without chirping.

  16. Thomson scattering in high-intensity chirped laser pulses

    SciTech Connect

    Holkundkar, Amol R.; Harvey, Chris Marklund, Mattias

    2015-10-15

    We consider the Thomson scattering of an electron in an ultra-intense laser pulse. It is well known that at high laser intensities, the frequency and brilliance of the emitted radiation will be greatly reduced due to the electron losing energy before it reaches the peak field. In this work, we investigate the use of a small frequency chirp in the laser pulse in order to mitigate this effect of radiation reaction. It is found that the introduction of a negative chirp means the electron enters a high frequency region of the field while it still has a large proportion of its original energy. This results in a significant enhancement of the frequency and intensity of the emitted radiation as compared to the case without chirping.

  17. Intensity fluctuations of ultrasonic scattering in a highly turbulent flow.

    PubMed

    Shen, C; Lemmin, U

    2000-05-01

    Aspects of ultrasound intensity fluctuations backscattered from additive microstructures in a turbulent flow have been investigated theoretically and experimentally for the conditions of a small insonified volume, a high sound frequency and strong turbulence. These conditions are typically found in high resolution Doppler sonar applications. An easily applicable expression for the auto-correlation of scattering intensity fluctuations is obtained by introducing open-channel turbulence theory, a semi-empirical scalar spectrum (including a Batchelor spectrum) and a Gaussian window function. Experiments carried out in a laboratory-clear water, open-channel flow for different turbulence levels verify the underlying assumptions. A good agreement is found with the predictions made with the above-derived expression. The feasibility of extracting flow information from the backscattered intensity fluctuations is discussed. PMID:10857575

  18. Short-pulse, high-intensity lasers at Los Alamos

    SciTech Connect

    Taylor, A.J.; Roberts, J.P.; Rodriguez, G.; Fulton, R.D.; Kyrala, G.A.; Schappert, G.T.

    1994-03-01

    Advances in ultrafast lasers and optical amplifiers have spurred the development of terawatt-class laser systems capable of delivering focal spot intensities approaching 10{sup 20} W/cm{sup 2}. At these extremely high intensities, the optical field strength is more than twenty times larger than the Bohr electric field, permitting investigations of the optical properties of matter in a previously unexplored regime. The authors describe two laser systems for high intensity laser interaction experiments: The first is a terawatt system based on amplification of femtosecond pulses in XeCl which yields 250 mJ in 275 fs and routinely produces intensifies on target in excess of 10{sup 18} W/cm{sup 2}. The second system is based on chirped pulse amplification of 100-fs pulses in Ti:sapphire.

  19. Degradation of blue AlGaN/InGaN/GaN LEDs subjected to high current pulses

    SciTech Connect

    Barton, D.L.; Zeller, J.; Phillips, B.S.; Chiu, P.C.; Askar, S.; Lee, D.S.; Osinski, M.; Malloy, K.J.

    1994-12-31

    Short-wavelength, visible-light emitting optoelectronic devices are needed for a wide range of commercial applications, including high-density optical data storage, full-color displays, and underwater communications. In 1994, high-brightness blue LEDs based on gallium nitride and related compounds (InGaN/AlGaN) were introduced by Nichia Chemical Industries. The Nichia diodes are 100 times brighter than the previously available SiC blue LEDs. Group-III nitrides combine a wide, direct bandgap with refractory properties and high physical strength. So far, no studies of degradation of GaN based LEDs have been reported. The authors study, reported in this paper, focuses on the performance of GaN LEDs under high electrical stress conditions. Their observations indicate that, in spite of a high defect density, which normally would have been fatal to other III-V devices, defects in group-III nitrides are not mobile even under high electrical stress. Defect tubes, however, can offer a preferential path for contact metals to electromigrate towards the p-n junction, eventually resulting in a short. The proposed mechanism of GaN diode degradation raises concern for prospects of reliable lasers in the group-III nitrides grown on sapphire.

  20. Drift tube suspension for high intensity linear accelerators

    DOEpatents

    Liska, Donald J.; Schamaun, Roger G.; Clark, Donald C.; Potter, R. Christopher; Frank, Joseph A.

    1982-01-01

    The disclosure relates to a drift tube suspension for high intensity linear accelerators. The system comprises a series of box-sections girders independently adjustably mounted on a linear accelerator. A plurality of drift tube holding stems are individually adjustably mounted on each girder.

  1. Drift tube suspension for high intensity linear accelerators

    DOEpatents

    Liska, D.J.; Schamaun, R.G.; Clark, D.C.; Potter, R.C.; Frank, J.A.

    1980-03-11

    The disclosure relates to a drift tube suspension for high intensity linear accelerators. The system comprises a series of box-sections girders independently adjustably mounted on a linear accelerator. A plurality of drift tube holding stems are individually adjustably mounted on each girder.

  2. High-Intensity Interval Training for Improving Postprandial Hyperglycemia

    ERIC Educational Resources Information Center

    Little, Jonathan P.; Francois, Monique E.

    2014-01-01

    High-intensity interval training (HIIT) has garnered attention in recent years as a time-efficient exercise option for improving cardiovascular and metabolic health. New research demonstrates that HIIT may be particularly effective for improving postprandial hyperglycemia in individuals with, or at risk for, type 2 diabetes (T2D). These findings…

  3. Nonlinear behavior in high-intensity discharge lamps

    NASA Astrophysics Data System (ADS)

    Baumann, Bernd; Schwieger, Joerg; Wolff, Marcus; Manders, Freddy; Suijker, Jos

    2016-06-01

    The light flicker problem of high intensity discharge lamps is studied numerically and experimentally. It is shown that in some respects the systems behave very similar to the forced Duffing oscillator with a softening spring. In particular, the jump phenomenon and hysteresis are observed in the simulations and in the experiments.

  4. Risking Intensity: Reading and Writing Poetry with High School Students.

    ERIC Educational Resources Information Center

    Michaels, Judith Rowe

    Aimed at junior and senior high school teachers and artists in residence, this book urges teachers and students to read and write poetry "as though their lives depended upon it," and to breathe life into classroom writing traditions that are not hands-on or intense. Each chapter is set in the classroom. Poems by students and teacher illustrate…

  5. Critical design issues of high intensity proton linacs

    SciTech Connect

    Lawrence, G.P.

    1994-08-01

    Medium-energy proton linear accelerators are being studied as drivers for spallation applications requiring large amounts of beam powder. Important design factors for such high-intensity linacs are reviewed, and issues and concerns specific to this unprecedented power regime are discussed.

  6. Semi-polar GaN materials technology for high IQE green LEDs.

    SciTech Connect

    Koleske, Daniel David; Lee, Stephen Roger; Crawford, Mary Hagerott; Coltrin, Michael Elliott; Fini, Paul

    2013-06-01

    The goal of this NETL funded program was to improve the IQE in green (and longer wavelength) nitride- based LEDs structures by using semi-polar GaN planar orientations for InGaN multiple quantum well (MQW) growth. These semi-polar orientations have the advantage of significantly reducing the piezoelectric fields that distort the QW band structure and decrease electron-hole overlap. In addition, semipolar surfaces potentially provide a more open surface bonding environment for indium incorporation, thus enabling higher indium concentrations in the InGaN MQW. The goal of the proposed work was to select the optimal semi-polar orientation and explore wafer miscuts around this orientation that produced the highest quantum efficiency LEDs. At the end of this program we had hoped to have MQWs active regions at 540 nm with an IQE of 50% and an EQE of 40%, which would be approximately twice the estimated current state-of-the-art.

  7. High efficiency GaN-based LEDs and lasers on SiC

    NASA Astrophysics Data System (ADS)

    Edmond, John; Abare, Amber; Bergman, Mike; Bharathan, Jayesh; Lee Bunker, Kristin; Emerson, Dave; Haberern, Kevin; Ibbetson, James; Leung, Michael; Russel, Phil; Slater, David

    2004-12-01

    Group III-nitride layers have been grown via metal-organic vapor-phase epitaxy (MOVPE) on single crystal-silicon carbide (SiC) substrates and fabricated into light-emitting diodes (LEDs) and laser diodes (LDs). Deep ultraviolet (UV) LEDs from 321 to 343 nm operating at 20 mA and 4.1 V exhibit an output of 0.2-2.9 mW, respectively, corresponding to an external quantum efficiency (EQE) of 0.26-4.0%. In the visible spectrum, an EQE of ˜47% was achieved in the blue at 455-460 nm corresponding to an output of 25.5 mW at 20 mA and 3.1 V. The value of EQE decreased to ˜30% at 395 nm (violet) and ˜22% at 535 nm (green). Interaction between defects and charge carriers is speculated to dominate the radiative recombination process at shorter wavelengths (<˜440 nm) whereas evidence is presented that piezoelectric polarization dominates at longer wavelengths, predominantly in the green. White LEDs have been fabricated using 24 mW blue chips via phosphor excitation and exhibit luminous efficacies of 78 lumens/W, which is considerably more efficient than standard incandescent bulbs. Continuous-wave (CW) LD operation from 348-410 nm, and pulsed operation as short as 343 nm were achieved.

  8. Piezoelectric field in highly stressed GaN-based LED on Si (1 1 1) substrate

    NASA Astrophysics Data System (ADS)

    Tawfik, Wael Z.; Hyun, Gil Yong; Ryu, Sang-Wan; Ha, June Seok; Lee, June Key

    2016-05-01

    Stress states in GaN epilayers grown on Si (1 1 1) and c-plane sapphire, and their effects on built-in piezoelectric field induced by compressive stress in InGaN/GaN multi-quantum well (MQW) light-emitting diodes (LEDs) were investigated using the electroreflectance (ER) spectroscopic technique. Relatively large tensile stress is observed in GaN epilayers grown on Si (1 1 1), while a small compressive stress appears in the film grown on c-plane sapphire. The InGaN/GaN MQWs of LED on c-plane sapphire substrate has a higher piezoelectric field than the MQWs of LEDs on Si (1 1 1) substrate by about 1.04 MV/cm. The large tensile stress due to lattice mismatch with Si (1 1 1) substrate is regarded as external stress. The external tensile stress from the Si substrate effectively compensates for the compressive stress developed in the active region of the InGaN/GaN MQWs, thus reducing the quantum-confined Stark effect (QCSE) by attenuating the piezoelectric polarization from the InGaN layer.

  9. Introduction of the moth-eye patterned sapphire substrate technology for cost-effective high-performance LEDs

    NASA Astrophysics Data System (ADS)

    Naniwae, K.; Mori, M.; Kondo, T.; Suzuki, A.; Kitano, T.; Kamiyama, S.; Iwaya, M.; Takeuchi, T.; Akasaki, I.

    2013-03-01

    The improvement of the performance and the reduction of the cost for LEDs using the moth-eye patterned sapphire substrate (MPSS) were investigated. TEM and CL observation results clearly show that the MPSS can provide a thinner GaN template of equal or higher quality than the micron scale patterned sapphire substrate (PSS) since the MPSS only has a submicron scale structure. A 3-μm-thick high quality GaN template on the MPSS with a dislocation density of 1.9×108 cm-2 has been demonstrated. The LEDs on MPSS with a 600 nm pitch show the highest light output among the evaluated LEDs on various types of substrates as it is 1.52 times higher than that on flat sapphire substrate (FSS) and 1.18 times higher than that on PSS. The pitch dependence of the light output improvement is in excellent agreement with that of the transmittance at GaN/sapphire interface simulated by the rigorous coupled wave analysis. As a result of comparisons for the GaN templates and LEDs on MPSS, PSS and FSS, it can be concluded that MPSS provides the most cost effective solution for high performance LED.

  10. Beta-alanine supplementation in high-intensity exercise.

    PubMed

    Harris, Roger C; Sale, Craig

    2012-01-01

    Glycolysis involves the oxidation of two neutral hydroxyl groups on each glycosyl (or glucosyl) unit metabolised, yielding two carboxylic acid groups. During low-intensity exercise these, along with the remainder of the carbon skeleton, are further oxidised to CO(2) and water. But during high-intensity exercise a major portion (and where blood flow is impaired, then most) is accumulated as lactate anions and H(+). The accumulation of H(+) has deleterious effects on muscle function, ultimately impairing force production and contributing to fatigue. Regulation of intracellular pH is achieved over time by export of H(+) out of the muscle, although physicochemical buffers in the muscle provide the first line of defence against H(+) accumulation. In order to be effective during high-intensity exercise, buffers need to be present in high concentrations in muscle and have pK(a)s within the intracellular exercise pH transit range. Carnosine (β-alanyl-L-histidine) is ideal for this role given that it occurs in millimolar concentrations within the skeletal muscle and has a pK(a) of 6.83. Carnosine is a cytoplasmic dipeptide formed by bonding histidine and β-alanine in a reaction catalysed by carnosine synthase, although it is the availability of β-alanine, obtained in small amounts from hepatic synthesis and potentially in greater amounts from the diet that is limiting to synthesis. Increasing muscle carnosine through increased dietary intake of β-alanine will increase the intracellular buffering capacity, which in turn might be expected to increase high-intensity exercise capacity and performance where this is pH limited. In this study we review the role of muscle carnosine as an H(+) buffer, the regulation of muscle carnosine by β-alanine, and the available evidence relating to the effects of β-alanine supplementation on muscle carnosine synthesis and the subsequent effects of this on high-intensity exercise capacity and performance. PMID:23075550

  11. High-intensity laser heating in liquids: Multiphoton absorption

    SciTech Connect

    Longtin, J.P.; Tien, C.L.

    1995-12-31

    At high laser intensities, otherwise transparent liquids can absorb strongly by the mechanism of multiphoton absorption, resulting in absorption and heating several orders of magnitude greater than classical, low-intensity mechanisms. The use of multiphoton absorption provides a new mechanism for strong, controlled energy deposition in liquids without bulk plasma formation, shock waves, liquid ejection, etc., which is of interest for many laser-liquid applications, including laser desorption of liquid films, laser particle removal, and laser water removal from microdevices. This work develops a microscopically based model of the heating during multiphoton absorption in liquids. The dependence on pulse duration, intensity, wavelength, repetition rate, and liquid properties is discussed. Pure water exposed to 266 nm laser radiation is investigated, and a novel heating mechanism for water is proposed that uses multiple-wavelength laser pulses.

  12. Accurate colorimetric feedback for RGB LED clusters

    NASA Astrophysics Data System (ADS)

    Man, Kwong; Ashdown, Ian

    2006-08-01

    We present an empirical model of LED emission spectra that is applicable to both InGaN and AlInGaP high-flux LEDs, and which accurately predicts their relative spectral power distributions over a wide range of LED junction temperatures. We further demonstrate with laboratory measurements that changes in LED spectral power distribution with temperature can be accurately predicted with first- or second-order equations. This provides the basis for a real-time colorimetric feedback system for RGB LED clusters that can maintain the chromaticity of white light at constant intensity to within +/-0.003 Δuv over a range of 45 degrees Celsius, and to within 0.01 Δuv when dimmed over an intensity range of 10:1.

  13. Radiation control in the intensive care unit for high intensity iridium-192 brain implants

    SciTech Connect

    Sewchand, W.; Drzymala, R.E.; Amin, P.P.; Salcman, M.; Salazar, O.M.

    1987-04-01

    A bedside lead cubicle was designed to minimize the radiation exposure of intensive care unit staff during routine interstitial brain irradiation by removable, high intensity iridium-192. The cubicle shields the patient without restricting intensive care routines. The design specifications were confirmed by exposure measurements around the shield with an implanted anthropomorphic phantom simulating the patient situation. The cubicle reduces the exposure rate around an implant patient by as much as 90%, with the exposure level not exceeding 0.1 mR/hour/mg of radium-equivalent /sup 192/Ir. Evaluation of data accumulated for the past 3 years has shown that the exposure levels of individual attending nurses are 0.12 to 0.36 mR/mg of radium-equivalent /sup 192/Ir per 12-hour shift. The corresponding range for entire nursing teams varies between 0.18 and 0.26. A radiation control index (exposure per mg of radium-equivalent /sup 192/Ir per nurse-hour) is thus defined for individual nurses and nursing teams; this index is a significant guide to the planning of nurse rotations for brain implant patients with various /sup 192/Ir loads. The bedside shield reduces exposure from /sup 192/Ir implants by a factor of about 20, as expected, and the exposure from the lower energy radioisotope iodine-125 is barely detectable.

  14. Analgesic effect of high intensity laser therapy in knee osteoarthritis.

    PubMed

    Stiglić-Rogoznica, Nives; Stamenković, Doris; Frlan-Vrgoc, Ljubinka; Avancini-Dobrović, Viviana; Vrbanić, Tea Schnurrer-Luke

    2011-09-01

    Knee osteoarthritis (KOA), the most common type of osteoarthritis (OA), is associated with pain and inflammation of the joint capsule, impaired muscular stabilization, reduced range of motion and functional disability. High-intensity laser therapy (HILT) involves higher-intensity laser radiation and causes minor and slow light absorption by chromophores. Light stimulation of the deep structures, due to high intensity laser therapy, activates cell metabolism through photochemical effect. The transmissions of pain stimulus are slowed down and result in a quick achievement of pain relief. The aim of our research was to investigate the prompt analgesic effect of HILT on patients with KOA. Knee radiographs were performed on all patients and consequently graded using the Kellgren-Lawrence grading scale (K/L). A group of 96 patients (75 female, 21 male, mean age 59.2) with K/L 2 and 3 were submitted to HILT therapy. Pain intensity was evaluated with visual analogue scale (VAS) before and after the treatment. HILT consisted in one daily application, over a period of ten days, using protocol wavelength, frequency and duration. The results showed statistically significant decrease in VAS after the treatment (p < 0.001). Considering these results, HILT enables prompt analgesic effects in KOA treatment. Therefore HILT is a reliable option in KOA physical therapy. PMID:22220431

  15. Anomalies in high-order harmonic generation at relativistic intensities

    SciTech Connect

    Teubner, U.; Foerster, E.; Pretzler, G.; Eidmann, K.; Witte, K.; Schlegel, Th.

    2003-01-01

    High-order harmonic generation from a solid target surface has been investigated using femtosecond laser pulses focused to intensities greater than 10{sup 18} W/cm{sup 2}. The experiments show that the harmonics are very intense, with a conversion efficiency that is one or two orders of magnitude larger than that of harmonics generated in gases. Beside the observation of presently the shortest wavelength harmonics from femtosecond-laser solid target interaction, i.e., down to 22 nm, an anomaly has been observed in the harmonic spectrum. In contrast to the expected well-known continuous 'roll off' of the high-harmonic orders, the harmonic intensity decreases with the increase of harmonic order, but in between shows minima which are significantly less intense than the neighboring harmonics. Furthermore, the order of the harmonic minima depend on target material. Additional calculations using numerical kinetic particle simulations and a simpler oscillating mirror model show that the physical origin of these modulations is an intricate interplay of resonance absorption and ponderomotive force which leads to a complex electron density profile evolution. Furthermore, this is emphasized by a spectral line analysis of the harmonics. In agreement with the theory, broad lines have been observed and, in particular for the harmonics in the minima, a complex interference structure is present.

  16. Generation of Ultra-high Intensity Laser Pulses

    SciTech Connect

    N.J. Fisch; V.M. Malkin

    2003-06-10

    Mainly due to the method of chirped pulse amplification, laser intensities have grown remarkably during recent years. However, the attaining of very much higher powers is limited by the material properties of gratings. These limitations might be overcome through the use of plasma, which is an ideal medium for processing very high power and very high total energy. A plasma can be irradiated by a long pump laser pulse, carrying significant energy, which is then quickly depleted in the plasma by a short counterpropagating pulse. This counterpropagating wave effect has already been employed in Raman amplifiers using gases or plasmas at low laser power. Of particular interest here are the new effects which enter in high power regimes. These new effects can be employed so that one high-energy optical system can be used like a flashlamp in what amounts to pumping the plasma, and a second low-power optical system can be used to extract quickly the energy from the plasma and focus it precisely. The combined system can be very compact. Thus, focused intensities more than 10{sup 25} W/cm{sup 2} can be contemplated using existing optical elements. These intensities are several orders of magnitude higher than what is currently available through chirped pump amplifiers.

  17. A high intensity positron beam at the Brookhaven reactor

    SciTech Connect

    Weber, M.; Lynn, K.G.; Roellig, L.O.; Mills, A.P. Jr.; Moodenbaugh, A.R.

    1987-01-01

    We describe a high intensity, low energy positron beam utilizing high specific activity /sup 64/Cu sources (870 Ci/g) produced in a reactor with high thermal neutron flux. Fast-to-slow moderation can be performed in a self moderation mode or with a transmission moderator. Slow positron rates up to 1.6 x 10/sup 8/ e/sup +//s with a half life of 12.8 h are calculated. Up to 1.0 x 10/sup 8/ e/sup +//s have been observed. New developments including a Ne moderator and an on-line isotope separation process are discussed. 21 refs., 9 figs.

  18. HELIOS: A high intensity chopper spectrometer at LANSCE

    SciTech Connect

    Mason, T.E.; Broholm, C.; Fultz, B.

    1998-12-31

    A proposal to construct a high intensity chopper spectrometer at LANSCE as part of the SPSS upgrade project is discussed. HELIOS will be optimized for science requiring high sensitivity neutron spectroscopy. This includes studies of phonon density of states in small polycrystalline samples, magnetic excitations in quantum magnets and highly correlated electron systems, as well as parametric studies (as a function of pressure, temperature, or magnetic field) of S(Q,{omega}). By employing a compact design together with the use of supermirror guide in the incident flight path the neutron flux at HELIOS will be significantly higher than any other comparable instrument now operating.

  19. BEAM HALO FORMATION IN HIGH-INTENSITY BEAMS.

    SciTech Connect

    FEDOTOV, A.V.

    2005-03-18

    Studies of beam halo became unavoidable feature of high-intensity machines where uncontrolled beam loss should be kept to extremely small level. For a well controlled stable beam such a loss is typically associated with the low density halo surrounding beam core. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation in a specific machine of interest. The dominant mechanisms are, in fact, different in linear accelerators, circular machines or Energy Recovering Linacs (ERL). In this paper, we summarize basic mechanisms of halo formation in high-intensity beams and discuss their application to various types of accelerators of interest, such as linacs, rings and ERL.

  20. High-Intensity Focused Ultrasound Therapy: an Overview for Radiologists

    PubMed Central

    Kim, Young-sun; Choi, Min Joo; Lim, Hyo Keun; Choi, Dongil

    2008-01-01

    High-intensity focused ultrasound therapy is a novel, emerging, therapeutic modality that uses ultrasound waves, propagated through tissue media, as carriers of energy. This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery. However, the application of this technology still has many drawbacks. It is expected that current obstacles to implementation will be resolved in the near future. In this review, we provide an overview of high-intensity focused ultrasound therapy from the basic physics to recent clinical studies with an interventional radiologist's perspective for the purpose of improving the general understanding of this cutting-edge technology as well as speculating on future developments. PMID:18682666

  1. Fermilab main injector: High intensity operation and beam loss control

    NASA Astrophysics Data System (ADS)

    Brown, Bruce C.; Adamson, Philip; Capista, David; Chou, Weiren; Kourbanis, Ioanis; Morris, Denton K.; Seiya, Kiyomi; Wu, Guan Hong; Yang, Ming-Jen

    2013-07-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at 400 kW beam power. Transmission was very high except for beam lost at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the improvements required to achieve high intensity, the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  2. High intensity muon beam source for neutrino beam experiments

    NASA Astrophysics Data System (ADS)

    Kamal Sayed, Hisham

    2015-09-01

    High intensity muon beams are essential for Muon accelerators like Neutrino Factories and Muon Colliders. In this study we report on a global optimization of the muon beam production and capture based on end-to-end simulations of the Muon Front End. The study includes the pion beam production target geometry, capture field profile, and forming muon beam into microbunches for further acceleration. The interplay between the transverse and longitudinal beam dynamics during the capture and transport of muon beam is evaluated and discussed. The goal of the optimization is to provide a set of design parameters that delivers high intensity muon beam that could be fit within the acceptance of a muon beam accelerator.

  3. Enhancement of vasorelaxation in hypertension following high-intensity exercise.

    PubMed

    Yang, Ai-Lun; Lo, Chia-Wen; Lee, Jen-Ting; Su, Chia-Ting

    2011-04-30

    Exercise can ameliorate vascular dysfunction in hypertension, but its underlying mechanism has not been explored thoroughly. We aimed to investigate whether the high-intensity exercise could enhance vasorelaxation mediated by insulin and insulin-like growth factor-1 (IGF-1) in hypertension. Sixteen-week-old spontaneously hypertensive rats were randomly divided into non-exercise sedentary (SHR) and high-intensity exercise (SHR+Ex) groups conducted by treadmill running at a speed of 30 m/ min until exhaustion. Age-matched Wistar-Kyoto rats (WKY) were used as the normotensive control group. Immediately after exercise, the agonist-induced vasorelaxation of aortas was evaluated in organ baths with or without endothelial denudation. Selective inhibitors were used to examine the roles of nitric oxide synthase (NOS) and phosphatidylinositol-3 kinase (PI3K) in the vasorelaxation. By adding superoxide dismutase (SOD), a superoxide scavenger, the role of superoxide production in the vasorelaxation was also clarified. We found that, the high-intensity exercise significantly (P < 0.05) induced higher vasorelaxant responses to insulin and IGF-1 in the SHR+Ex group than that in the SHR group; after endothelial denudation and pre-treatment of the PI3K inhibitor, NOS inhibitor, or SOD, vasorelaxant responses to insulin and IGF-1 became similar among three groups; the protein expression of insulin receptor, IGF-1 receptor, and endothelial NOS (eNOS) was significantly (P < 0.05) increased in the SHR+Ex group compared with the SHR group;] the relaxation to sodium nitroprusside, a NO donor, was not different among three groups. Our findings suggested that the high-intensity exercise ameliorated the insulin- and IGF-1-mediated vasorelaxation through the endothelium-dependent pathway, which was associated with the reduced level of superoxide production. PMID:21789889

  4. NUMERICAL METHODS FOR THE SIMULATION OF HIGH INTENSITY HADRON SYNCHROTRONS.

    SciTech Connect

    LUCCIO, A.; D'IMPERIO, N.; MALITSKY, N.

    2005-09-12

    Numerical algorithms for PIC simulation of beam dynamics in a high intensity synchrotron on a parallel computer are presented. We introduce numerical solvers of the Laplace-Poisson equation in the presence of walls, and algorithms to compute tunes and twiss functions in the presence of space charge forces. The working code for the simulation here presented is SIMBAD, that can be run as stand alone or as part of the UAL (Unified Accelerator Libraries) package.

  5. Spallation neutron source and other high intensity froton sources

    SciTech Connect

    Weiren Chou

    2003-02-06

    This lecture is an introduction to the design of a spallation neutron source and other high intensity proton sources. It discusses two different approaches: linac-based and synchrotron-based. The requirements and design concepts of each approach are presented. The advantages and disadvantages are compared. A brief review of existing machines and those under construction and proposed is also given. An R&D program is included in an appendix.

  6. Silicone rubber curing by high intensity infrared radiation

    SciTech Connect

    Huang, T.; Tsai, J.; Cherng, C.; Chen, J.

    1994-08-10

    A high-intensity (12 kW) and compact (80 cm) infrared heating oven for fast curing (12 seconds) of tube-like silicone rubber curing studies is reported. Quality inspection by DSC and DMA and results from pilot-scale curing oven all suggest that infrared heating provides a better way of vulcanization regarding to curing time, quality, cost, and spacing over conventional hot air heating. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  7. PULSED POWER APPLICATIONS IN HIGH INTENSITY PROTON RINGS.

    SciTech Connect

    ZHANG, S.Y.; SANDBERG, J.; ET AL.

    2005-05-16

    Pulsed power technology has been applied in particle accelerators and storage rings for over four decades. It is most commonly used in injection, extraction, beam manipulation, source, and focusing systems. These systems belong to the class of repetitive pulsed power. In this presentation, we review and discuss the history, present status, and future challenge of pulsed power applications in high intensity proton accelerators and storage rings.

  8. LED-based nondirectional infrared transceiver for high-speed indoor wireless data communication

    NASA Astrophysics Data System (ADS)

    Chen, George C. K.; New, Wei L.; Yao, Jianping; Venkateswarlu, Ronda

    2001-10-01

    A Line of Sight, non-directed transceiver system was designed and constructed. The transmitter is composed of two types of LEDs and are tilted at 60 degree(s) to achieve uniform light distribution up to 50 degrees across a plane. The receiver is composed of multiple silicon-pin-photodiodes, transimpedance amplifiers, bandpass filter and AGC, and has a half field of view of 60 degree. Software was written to design uniform distribution on a horizontal plane for non-directed line-of-sight system. Experimental testing was conducted in a room with size 3.4m x 5.1m x 2.6m and measured optical power shows close correspondence to the simulated power distribution. Non-return-to zero signal of certain test codes were transmitted at 34 Mbps, and collected signals indicate that the eye is widely open in the eye diagram.

  9. Low-cost high data rate white LED (WLED) transceiver development

    NASA Astrophysics Data System (ADS)

    Chan, Eric; Koshinz, Dennis; Krug, William; Hager, Harold

    2009-05-01

    Recently there has been strong interest in wireless white LED (WLED) communication link applications in airplanes and avionics platforms for size, weight, cost, and electromagnetic interference (EMI) reduction. Wireless WLED link has additional advantage of providing network security because the optical signal from WLED link is well confined within an airplane or avionics vehicle. In this paper we discuss and analyze commercial-off-he-shelf WLED design and color measurement results. An experimental implementation of a low cost WLED transceiver which shows error free freespace operation at 10Mb/s is successfully demonstrated. The feasibly of implementing free space optical link which meets both lighting and communication requirements using WLED array is analyzed by mathematical modeling using MATLAB simulation technique.

  10. Heat transparent high intensity high efficiency solar cell

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr. (Inventor)

    1982-01-01

    An improved solar cell design is described. A surface of each solar cell has a plurality of grooves. Each groove has a vertical face and a slanted face that is covered by a reflecting metal. Light rays are reflected from the slanted face through the vertical face where they traverse a photovoltaic junction. As the light rays travel to the slanted face of an adjacent groove, they again traverse the junction. The underside of the reflecting coating directs the light rays toward the opposite surface of solar cell as they traverse the junction again. When the light rays travel through the solar cell and reach the saw toothed grooves on the under side, the process of reflection and repeatedly traversing the junction again takes place. The light rays ultimately emerge from the solar cell. These solar cells are particularly useful at very high levels of insolation because the infrared or heat radiation passes through the cells without being appreciably absorbed to heat the cell.

  11. Employing low-temperature barriers to achieve strain-relaxed and high-performance GaN-based LEDs.

    PubMed

    Lin, Zhiting; Wang, Haiyan; Wang, Wenliang; Lin, Yunhao; Yang, Meijuan; Chen, Shuqi; Li, Guoqiang

    2016-05-30

    The epitaxial structure design of low-temperature barriers has been adopted to promote strain relaxation in multiple quantum well (MQWs) and achieve high-efficient GaN-based light-emitting diodes (LEDs). With these barriers, the relaxation value of wells increases from 0 to 4.59%. The strain-relaxed mechanism of low-temperature barriers is also discussed. The LED chip with the barriers grown at the TMIn flow of 75 sccm and the growth temperature of 830 °C has an optimal strain relaxation value of 1.53% in wells, and exhibits the largest light output power of 63.83 mW at the injection current of 65 mA, which is higher than that of conventional LED (51.89 mW) by 23%. In-depth studies reveal that the optimal low-temperature barriers remarkably promote the strain relaxation in wells without forming large density of crystalline defects. This achievement of high-efficiency LEDs sheds light on the future solid-state lighting applications. PMID:27410111

  12. High Intensity Interval- vs Moderate Intensity- Training for Improving Cardiometabolic Health in Overweight or Obese Males: A Randomized Controlled Trial

    PubMed Central

    Fisher, Gordon; Brown, Andrew W.; Bohan Brown, Michelle M.; Alcorn, Amy; Noles, Corey; Winwood, Leah; Resuehr, Holly; George, Brandon; Jeansonne, Madeline M.; Allison, David B.

    2015-01-01

    Purpose To compare the effects of six weeks of high intensity interval training (HIIT) vs continuous moderate intensity training (MIT) for improving body composition, insulin sensitivity (SI), blood pressure, blood lipids, and cardiovascular fitness in a cohort of sedentary overweight or obese young men. We hypothesized that HIIT would result in similar improvements in body composition, cardiovascular fitness, blood lipids, and SI as compared to the MIT group, despite requiring only one hour of activity per week compared to five hours per week for the MIT group. Methods 28 sedentary overweight or obese men (age, 20 ± 1.5 years, body mass index 29.5 ± 3.3 kg/m2) participated in a six week exercise treatment. Participants were randomly assigned to HIIT or MIT and evaluated at baseline and post-training. DXA was used to assess body composition, graded treadmill exercise test to measure cardiovascular fitness, oral glucose tolerance to measure SI, nuclear magnetic resonance spectroscopy to assess lipoprotein particles, and automatic auscultation to measure blood pressure. Results A greater improvement in VO2peak was observed in MIT compared to HIIT (11.1% vs 2.83%, P = 0.0185) in the complete-case analysis. No differences were seen in the intention to treat analysis, and no other group differences were observed. Both exercise conditions were associated with temporal improvements in % body fat, total cholesterol, medium VLDL, medium HDL, triglycerides, SI, and VO2peak (P < 0.05). Conclusion Participation in HIIT or MIT exercise training displayed: 1) improved SI, 2) reduced blood lipids, 3) decreased % body fat, and 4) improved cardiovascular fitness. While both exercise groups led to similar improvements for most cardiometabolic risk factors assessed, MIT led to a greater improvement in overall cardiovascular fitness. Overall, these observations suggest that a relatively short duration of either HIIT or MIT training may improve cardiometabolic risk factors in

  13. Radiation protection for an ultra-high intensity laser.

    PubMed

    Borne, F; Delacroix, D; Gelé, J M; Massé, D; Amiranoff, F

    2002-01-01

    Radiological characterisation of an experimental chamber and other areas of an ultra-high intensity laser facility (-terawatt) revealed significant levels of X ray, gamma and neutron radiation. Different techniques were used to detect and measure this radiation: TLD. photographic film, bubble detectors and germanium spectrometry. A test series of radiological measurements was made for 150 laser shots (300 femtoseconds) with energies in the 1 to 20 J range and a target illuminance of 10(19) W.cm2. Gamma dose equivalents in the vicinity of the chamber varied between 0.7 and 73 mSv. The dose equivalent due to the neutron component was evaluated to be 1% of the gamma dose equivalent. The amount of radiation generated depends on the laser energy and the nature of the target. No activation or contamination of the chamber or target holder were observed. Ultra-high intensity lasers are being extensively developed at the present time and the investigations performed demonstrate that it is necessary to take radiological risks into consideration in the design of ultra-high intensity laser facilities and to define personnel access conditions. PMID:12212903

  14. LED Update

    SciTech Connect

    Johnson, Mark L.; Gordon, Kelly L.

    2006-09-01

    This article, which will appear in RESIDENTIAL LIGHTING MAGAZINE, interviews PNNL's Kelly Gordon and presents the interview in question and answer format. The topic is a light emitting diode (LED) lighting also known as solid state lighting. Solid state lighting will be a new category in an energy efficient lighting fixture design competition called Lighting for Tomorrow sponsored by the US Department of Energy Emerging Technologies Office, the American Institute for Lighting, and the Consortium for Energy Efficiency. LED technology has been around since the ’60s, but it has been used mostly for indicator lights on electronics equipment. The big breakthrough was the development in the 1990s of blue LEDs which can be combined with the red and green LEDs that already existed to make white light. LEDs produce 25 to 40 lumens of light per watt of energy used, almost as much as a CFL (50 lumens per watt) and much more efficient than incandescent sources, which are around 15 lumens per watt. They are much longer lived and practical in harsh environments unsuitable for incandescent lighting. They are ready for niche applications now, like under-counter lighting and may be practical for additional applications as technological challenges are worked out and the technology is advancing in leaps and bounds.

  15. LED applications in biomedicine

    NASA Astrophysics Data System (ADS)

    Liu, Timon C.; Huang, Ping; Liu, Jiang; Yin, Jian-Ling; Fan, Guang-Han; Liu, Song-Hao

    2003-12-01

    Light-emitting diode (LED) technology has provided medicine with a new tool capable of delivering light deep into tissues of the body, at wavelengths which are biologically optimal for cancer treatment, wound healing and other clinical applications. In this paper, a simple review on the clinical use in therapeutic applications as well as in laboratory work of LEDs is given in view of low intensity laser irradiation effects in biomedicine.

  16. Transport of intense beams of highly charged ions

    NASA Astrophysics Data System (ADS)

    Winkler, M.; Gammino, S.; Ciavola, G.; Celona, L.; Spadtke, P.; Tinschert, K.

    2005-10-01

    The new generation of ion sources delivers beams with intensities of several mA. This requires a careful design of the analysing system and the low-energy beam transport (LEBT) from the source to the subsequent systems. At INFN-LNS, high intensity proton sources (TRIPS [L. Celona, G. Ciavola, S. Gammino et al ., Rev. Sci. Instrum. 75(5) 1423 (2004)], PM-TRIPS [G. Ciavola, L. Celona, S. Gammino et al ., Rev. Sci. Instrum. 75(5) 1453 (2004)]) as well as ECR ion sources for the production of highly charged high-intensity heavy ion beams are developed (SERSE [S. Gammino, G. Ciavola, L. Celona et al ., Rev. Sci. Instrum. 72(11) 4090 (2001), and references therein], GyroSERSE [S. Gammino et al ., Rev. Sci. Instrum. 75(5) 1637 (2004)], MS-ECRIS [G. Ciavola et al ., (2005), 11th Int. Conf. on Ion Sources, Caen, (in press)]). In this paper, we present ion-optical design studies of various LEBT systems for ion-sources devoted to the production of intense beams. Calculations were performed using the computer codes GIOS [H. Wollnik, J. Brezina and M. Berz, NIM A 258 (1987)], GICO [M. Berz, H.C. Hoffmann, and H. Wollnik, NIM A 258 (1987)], and TRANSPORT [K.L. Brown, F. Rothacker and D.C. Carey, SLAC-R-95-462, Fermilab-Pub-95/069, UC-414 (1995)]. Simulations take into account the expected phase space growth of the beam emittance due to space-charge effects and image aberrations introduced by the magnetic elements.

  17. Adaptations to high-intensity intermittent exercise in rodents.

    PubMed

    Bexfield, Nathan A; Parcell, Allen C; Nelson, W Bradley; Foote, Kristopher M; Mack, Gary W

    2009-09-01

    In humans, exercise-induced plasma volume (PV) expansion is typically associated with an increase in plasma albumin content, due in part to an increase in hepatic albumin synthesis. We tested the ability of a 12-day high-intensity intermittent exercise protocol to induce an increase in PV in rodents. Since albumin synthesis is transcriptionally regulated, we tested the hypothesis that exercise training would induce an increase in hepatic albumin gene expression. Fifty adult male Sprague-Dawley rats weighing between 245 and 350 g were randomly assigned to one of five groups: cage control (CC), sham exercise (sham), continuous moderate-intensity exercise training (MI), high-intensity intermittent exercise training (HI), or a single day of HI training (1-HI). Twenty-four hours after the last training session, rats were anesthetized. PV was determined, and the liver was removed, flash frozen, and stored for later analysis. Citrate synthase (CS) activity of the red quadriceps muscle, a marker of aerobic adaptation, increased with training (MI and HI) and in response to 1-HI (P < 0.05). We did not see a significant exercise-induced PV expansion as PV averaged 23.6 +/- 2.7 ml/kg body wt in the CC group and 26.6 +/- 1.3 ml/kg body wt in the HI group (P > 0.05). However, hepatic albumin mRNA expression, as determined by real-time PCR, increased 2.9 +/- 0.4- and 4.1 +/- 0.4-fold after MI and HI, respectively, compared with CC. A single bout of HI (1-HI) did not alter hepatic albumin mRNA expression. These data demonstrate an increase in both CS activity and hepatic albumin gene expression with 12 days of aerobic exercise training in the rodent with a rapid (within 24 h) adaptation in the skeletal muscle to high-intensity intermittent exercise. PMID:19608925

  18. LED lamp

    SciTech Connect

    Galvez, Miguel; Grossman, Kenneth; Betts, David

    2013-11-12

    There is herein described a lamp for providing white light comprising a plurality of light sources positioned on a substrate. Each of said light sources comprises a blue light emitting diode (LED) and a dome that substantially covers said LED. A first portion of said blue light from said LEDs is transmitted through said domes and a second portion of said blue light is converted into a red light by a first phosphor contained in said domes. A cover is disposed over all of said light sources that transmits at least a portion of said red and blue light emitted by said light sources. The cover contains a second phosphor that emits a yellow light in response to said blue light. The red, blue and yellow light combining to form the white light and the white light having a color rendering index (CRI) of at least about 80.

  19. Survey of proposed high intensity accelerators and their applications

    SciTech Connect

    Schriber, S.O.

    1994-09-01

    Many interesting applications are being considered for high intensity accelerators. Implications of the technology developments that are enhancing these opportunities, or making them possible, will be covered in context of the applications. Applications include those for research (in areas such as material science, biological sciences, nuclear and high energy physics), accelerator-driven transmutation technologies, defense, and medicine. Specific examples will be used to demonstrate the impact that technology development can have and how transfer of this technology to industry can have an impact in the consumer and commercial arenas. Technology Development in rf power, controls, beam optics, rf structures, magnets, injectors, and beam halos will be considered.

  20. High intensity line source for x-ray spectrometer calibration

    SciTech Connect

    Thoe, R.S.

    1986-06-01

    A high intensity electron-impact x-ray source using a one-dimensional Pierce lens has been built for the purpose of calibrating a bent crystal x-ray spectrometer. This source focuses up to 100 mA of 20-keV electrons to a line on a liquid-cooled anode. The line (which can serve as a virtual slit for the spectrometer) measures approximately 800 ..mu.. x 2 cm. The source is portable and therefore adaptable to numerous types of spectrometer applications. One particular application, the calibration of a high resolution (r = 10/sup 4/) time-resolved cyrstal spectrometer, will be discussed in detail.

  1. LEDs in automotive lighting

    NASA Astrophysics Data System (ADS)

    Eichhorn, Karsten

    2006-02-01

    Light emitting diodes (LED) are becoming more and more significant in interior and exterior automotive lighting. The long service life, energy and space savings, shock and vibration resistance and new styling potential are the main advantages of using LEDs in automotive applications. Today, most central high mounted stop lamps use LEDs. In rear combination lamps the number of LEDs in amber and red is increasing rapidly. This year, a first rear combination lamp using LEDs for all functionalities including the back-up lamp function was realized. In addition, first signal functions in headlamps using white High Power LEDs were launched onto the market. The long service life characteristic makes LEDs especially predestined for the DRL function combined with the position/parking light. Exterior automotive applications, including requirements and performance will be discussed and an outlook will be given on future scenarios.

  2. The different effects of high intensity interval training and moderate intensity interval training for weightlessness countermeasures

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Jie; Cheng, Tan; Zhi-Li, Li; Hui-juan, Wang; Wen-juan, Chen; Jianfeng, Zhang; Desheng, Wang; Dongbin, Niu; Qi, Zhao; Chengjia, Yang; Yanqing, Wang

    High intensity interval training (HIIT) has been demonstrated to improve performance in a relatively short training period. But the difference between high intensity interval training and moderate intensity interval training (MIIT) in simulated weightlessness still has not been well studied. This study sought to characterize the difference between 6 weeks high intensity interval training and moderate intensity interval training under reduced weight (RW) gait training device and zero-gravity locomotion system (ZLS). Twenty-three subjects (14M/4F, 32.5±4.5 years) volunteered to participate. They were divided into three groups, that were MITT (alternating 2 min at 40% VO _{2} peak and 2 min at 60% VO _{2} peak for 30min, five days per week) RW group (n=8), HITT (alternating 2 min at 40% VO _{2} peak and 2 min at 90% VO _{2} peak for 30min, three days per week) RW group (n=8) and HITT ZLS group (n=7). The Z-axis load used in RW group was 80% body weight (BW) and in ZLS was 100% BW. Cardiopulmonary function was measured before, after 4-week training and after 6-week training. Isokinetic knee extension-flexion test at 60(°) deg/s and 180(°) deg/s were performed before and after the 6-week training, and isometric knee extension-flexion test at 180(°) deg/s was also examined at the same time. It was found that the VO _{2} peaks, metabolic equivalent (MET), Speedmax and respiratory exchange ratio (RER) were significantly increased after 4 and 6-week training in all three groups and no significant group difference were detected. The peak torque at 60(°) deg/s for right knee flexion were significantly increased after 6 week-training in all three groups, and only in HITT RW group the total power at 60(°) deg/s for right knee flexion enhanced. The total power and average power at 60(°) deg/s for right knee extension decreased significantly after 6-week training in all three groups. The peak torque at 60(°) deg/s for right knee extension in MIIT RW group was

  3. High-intensity positron microprobe at Jefferson Lab

    SciTech Connect

    Golge, Serkan; Vlahovic, Branislav; Wojtsekhowski, Bogdan B.

    2014-06-19

    We present a conceptual design for a novel continuous wave electron-linac based high-intensity slow-positron production source with a projected intensity on the order of 1010 e+/s. Reaching this intensity in our design relies on the transport of positrons (T+ below 600 keV) from the electron-positron pair production converter target to a low-radiation and low-temperature area for moderation in a high-efficiency cryogenic rare gas moderator, solid Ne. The performance of the integrated beamline has been verified through computational studies. The computational results include Monte Carlo calculations of the optimized electron/positron beam energies, converter target thickness, synchronized raster system, transport of the beam from the converter target to the moderator, extraction of the beam from the channel, and moderation efficiency calculations. For the extraction of positrons from the magnetic channel a magnetic field terminator plug prototype has been built and experimental data on the effectiveness of this prototype are presented. The dissipation of the heat away from the converter target and radiation protection measures are also discussed.

  4. High-intensity positron microprobe at Jefferson Lab

    DOE PAGESBeta

    Golge, Serkan; Vlahovic, Branislav; Wojtsekhowski, Bogdan B.

    2014-06-19

    We present a conceptual design for a novel continuous wave electron-linac based high-intensity slow-positron production source with a projected intensity on the order of 1010 e+/s. Reaching this intensity in our design relies on the transport of positrons (T+ below 600 keV) from the electron-positron pair production converter target to a low-radiation and low-temperature area for moderation in a high-efficiency cryogenic rare gas moderator, solid Ne. The performance of the integrated beamline has been verified through computational studies. The computational results include Monte Carlo calculations of the optimized electron/positron beam energies, converter target thickness, synchronized raster system, transport of themore » beam from the converter target to the moderator, extraction of the beam from the channel, and moderation efficiency calculations. For the extraction of positrons from the magnetic channel a magnetic field terminator plug prototype has been built and experimental data on the effectiveness of this prototype are presented. The dissipation of the heat away from the converter target and radiation protection measures are also discussed.« less

  5. Resonant Auger Effect at High X-Ray Intensity

    SciTech Connect

    Rohringer, N; Santra, R

    2008-03-27

    The resonant Auger effect of atomic neon exposed to high-intensity x-ray radiation in resonance with the 1s {yields} 3p transition is discussed. High intensity here means that the x-ray peak intensity is sufficient ({approx} 10{sup 18} W/cm{sup 2}) to induce Rabi oscillations between the neon ground state and the 1s{sup -1}3p ({sup 1}P) state within the relaxation lifetime of the inner-shell vacancy. For the numerical analysis presented, an effective two-level model, including a description of the resonant Auger decay process, is employed. Both coherent and chaotic x-ray pulses are treated. The latter are used to simulate radiation from x-ray free-electron lasers based on the principle of self-amplified spontaneous emission. Observing x-ray-driven atomic population dynamics in the time domain is challenging for chaotic pulse ensembles. A more practical option for experiments using x-ray free-electron lasers is to measure the line profiles in the kinetic energy distribution of the resonant Auger electron. This provides information on both atomic population dynamics and x-ray pulse properties.

  6. Reducing, by pulse width modulation, the curing temperature of a prototype high-power LED light curing unit.

    PubMed

    Huang, Ta-Ko; Hung, Chun-Cheng; Tsai, Chi-Cheng

    2006-06-01

    Third-generation LEDs have high irradiance and efficiency, but the associated temperature rise is potentially hazardous to the pulp of teeth. We evaluated, during composite polymerization, the irradiance and temperature rise of a prototype high-power LED light curing unit (LCU) with optimal pulse width modulation (PWM), and then compared the results with four off-the-shelf high-power LCUs. A cavity was prepared in a tooth, and a composite resin layer was applied and cured. For each LCU, the irradiance and temperature changes at the pulp-dentin junction were measured. Microhardness (Vickers hardness) of cured composite samples was measured for each LCU. Our prototype had a final temperature of 36.4 +/- 1.3 degrees C and irradiance of 1,182 +/- 1 mW/cm2. The unit with the highest temperature had a temperature of 48.7 +/- 1.2 degrees C and an irradiance of 1,194 +/- 1 mW/cm2. Based on the results of the present study, it was shown that PWM technology reduced the curing temperature while retaining the polymerization effectiveness of a high-power LED LCU. PMID:16916235

  7. Short-pulse high intensity laser thin foil interaction

    NASA Astrophysics Data System (ADS)

    Audebert, Patrick

    2003-10-01

    The technology of ultrashort pulse laser generation has progressed to the point that optical pulses larger than 10 J, 300 fs duration or shorter are routinely produced. Such pulses can be focused to intensities exceeding 10^18 W/cm^2. With high contrast pulses, these focused intensities can be used to heat solid matter to high temperatures with minimal hydrodynamic expansion, producing an extremely high energy-density state of matter for a short period of time. This high density, high temperature plasma can be studied by x-ray spectroscopy. We have performed experiments on thin foils of different elements under well controlled conditions at the 100 Terawatt laser at LULI to study the characteristics X-ray emission of laser heated solids. To suppress the ASE effect, the laser was frequency doubled. S-polarized light with a peak intensity of 10^19W/cm^2 was used to minimize resonance absorption. To decrease the effect of longitudinal temperature gradients very thin (800 μ) aluminum foil targets were used. We have also studied the effect of radial gradient by limiting the measured x-ray emission zone using 50μ or 100μ pinhole on target. The spectra, in the range 7-8Å, were recorded using a conical crystal spectrometer coupled to a 800 fs resolution streak camera. A Fourier Domain Interferometry (FDI) of the back of the foil was also performed providing a measurement of the hydrodynamic expansion as function of time for each shot. To simulate the experiment, we used the 1D hydrodynamic code FILM with a given set of plasma parameter (ρ, Te) as initial conditions. The X-ray emission was calculated by post processing hydrodynamic results with a collisional-radiative model which uses super-configuration average atomic data. The simulation reproduces the main features of the experimental time resolved spectrum.

  8. High intensity accelerator for a wide range of applications

    NASA Astrophysics Data System (ADS)

    Conard, E. Milo

    1994-12-01

    When looking at commercial applications of accelerators from a market point of view, it appears that a common accelerator design could meet different users' needs. This would benefit both the manufacturer and the user by multiplying the number of machines sold, thus lowering their cost and improving their quality. These applications include: radioisotope production for medical imaging (positron emission tomography), industrial imaging and non-destructive testing (e.g. neutron radiography, explosive and drug detection in luggage or freight). This paper investigates the needs of the various applications and defines their common denominator to establish suitable specifications (type of particles, energy, intensity). Different accelerator types (cyclotrons, linear accelerators and electrostatic machines) are reviewed and compared on performance and estimated costs. A high intensity tandem accelerator design is studied in more detail as it seems the most appropriate candidate.

  9. Relative intensity noise in high speed microcavity laser

    NASA Astrophysics Data System (ADS)

    Tan, F.; Wu, M. K.; Liu, M.; Feng, M.; Holonyak, N.

    2013-09-01

    We have fabricated a high speed single mode microcavity laser of the form of oxide-confined vertical cavity surface emitting laser (VCSEL) and achieved an ultralow threshold current (ITH = 0.13 mA at 20 °C) with lasing wavelength at 837 nm. The optical spectrum of the microcavity VCSEL exhibits a mode spacing of 3.1 nm, which is corresponding to an optical modal cavity dimension of 2.5 μm. The device exhibits an enhanced modulation bandwidth of 22.6 GHz and a thermal noise limited laser intensity noise (electrical power spectral density of laser intensity noise below the thermal noise floor -174 dBm/Hz) as a consequence of low power laser operation and reduced mode competition in the microcavity.

  10. Free-field propagation of high intensity noise

    NASA Technical Reports Server (NTRS)

    Welz, Joseph P.; Mcdaniel, Oliver H.

    1990-01-01

    Observed spectral data from supersonic jet aircraft are known to contain much more high frequency energy than can be explained by linear acoustic propagation theory. It is believed that the high frequency energy is an effect of nonlinear distortion due to the extremely high acoustic levels generated by the jet engines. The objective, to measure acoustic waveform distortion for spherically diverging high intensity noise, was reached by using an electropneumatic acoustic source capable of generating sound pressure levels in the range of 140 to 160 decibels (re 20 micro Pa). The noise spectrum was shaped to represent the spectra generated by jet engines. Two microphones were used to capture the acoustic pressure waveform at different points along the propagation path in order to provide a direct measure of the waveform distortion as well as spectral distortion. A secondary objective was to determine that the observed distortion is an acoustic effect. To do this an existing computer prediction code that deals with nonlinear acoustic propagation was used on data representative of the measured data. The results clearly demonstrate that high intensity jet noise does shift the energy in the spectrum to the higher frequencies along the propagation path. In addition, the data from the computer model are in good agreement with the measurements, thus demonstrating that the waveform distortion can be accounted for with nonlinear acoustic theory.

  11. The development of a high intensity dance performance fitness test.

    PubMed

    Redding, Emma; Weller, Peter; Ehrenberg, Shantel; Irvine, Sarah; Quin, Edel; Rafferty, Sonia; Wyon, Matthew; Cox, Carol

    2009-01-01

    While there is currently a validated dance-specific exercise method of measuring aerobic fitness, no such test has been developed to measure high intensity capabilities in dance. The purpose of this study was to initiate an intermittent high intensity dance-specific fitness test. The test was designed to be able to observe changes in heart rate (HR), thereby allowing for a measurement of physical fitness at high intensities. Sixteen professional dancers (4 males and 12 females) volunteered to take part in this study. The fitness test protocol consists of movements that are representative of contemporary dance, and contains exercise and rest periods that mimic the intermittent nature of dance. The participants performed four trials. The physiological variables measured were HR (b.min(-1)) for each one minute bout of the four minute test for all trials, oxygen uptake (VO(2)) throughout the test, and end blood lactate (BLa mmol.L) for each trial. In addition, five of the participants undertook a maximal oxygen uptake treadmill test, and the scores obtained were compared with those from the dance test. Results show HR consistency across each one minute bout of the test and across each of the four trials of testing for all participants, indicating that the test is reliable. There was good reliability between bouts of each trial (typical error as % of CV = 1.5), intraclass "r" = 0.8, and good reliability between the four trials (typical error as % of CV = 2.1), intraclass "r" = 0.82. There were no significant differences between the maximal VO(2) and BLa scores established in the treadmill and dance tests, demonstrating validity. Thus, the results of this study indicate that the high intensity dance-specific test is a reliable and valid means of assessing and monitoring the cardiovascular fitness of dancers. The test allows dancers to be assessed within an environment that they are accustomed to (the studio), using a mode of exercise that is relevant (dance), and it is

  12. Design of LED freeform optical system for road lighting with high luminance/illuminance ratio.

    PubMed

    Feng, Zexin; Luo, Yi; Han, Yanjun

    2010-10-11

    A systematic method is proposed for designing an optical system for road lighting using an LED and a freeform lens that is optimized to produce a certain luminance distribution on the road surface. The proposed design method takes account of the luminance characteristics of the road surface, the energy efficiency of the system, the glare problem of the luminaire and the effects of four adjacent luminaries illuminating a single road surface. Firstly, the road surface illuminance with a polynomial of cosine functions along the road is optimized to maximize Q (the ratio of the average luminance to the average illuminance) as well as satisfying the lighting requirements provided by CIE. Then, a smooth freeform lens with this optimized illuminance is designed based on the variable separation method and the feedback modification method. Results show that, from two typical observer positions on the 2-lane C2 class road, luminaires with these freeform lenses can provide Q values of 7.90 × 10(-2) and 8.69 × 10(-2), the overall road surface luminance uniformity of 0.55 and 0.56, the longitudinal road surface luminance uniformity of 0.72 and 0.79, and the glare factors of 10.06% and 6.73% . PMID:20941103

  13. Thermal behavior of silicon-copper micro vapor chamber for high power LEDs

    NASA Astrophysics Data System (ADS)

    Luo, Yi; Li, Zhi-xin; Zhou, Chuan-peng; Wang, Xiao-dong; You, Bo

    2016-03-01

    Micro vapor chamber (MVC) for light emitting diodes (LEDs) can be designed and fabricated to enhance the heat dissipation efficiency and improve the reliability. In this paper, we used photoresist SU-8 and electroforming copper (Cu) to fabricate three kinds of wick structures, which are star, radiation and parallel ones, and the substrate is silicon with thickness of 0.5 mm. Electroforming Cu on silicon to make micro wick structure was a critical step, the ampere-hour factor was used, and accordingly the electroforming time was predicted. The composition of electroforming solution and parameters of electroforming were optimized too. After charging and packaging, thermal behavior tests were carried out to study the heat dissipation performance of MVCs. When the input power was 8 W, the parallel wick structure reached the equivalent temperature of 69.0 °C in 226 s, while the others were higher than that. The experimental results prove that the wick structures have significant influence on the heat transfer capability of MVCs.

  14. Optical and thermal properties of phosphors based on lead-silicate glass for high-power white LEDs

    NASA Astrophysics Data System (ADS)

    Shvaleva, M. A.; Tuzova, Yu. V.; Romanov, A. E.; Aseev, V. A.; Nikonorov, N. V.; Mynbaev, K. D.; Bugrov, V. E.

    2015-11-01

    A study is reported of the properties of a new phosphor material based on a highly refractive leadsilicate glass and microparticles of yttrium-aluminum garnet doped with cerium ions (YAG: Ce3+). The mass percentage fraction of YAG: Ce3+ microparticles in the material was varied from 50 to 90%. The optical properties of the phosphor were examined, as well as its thermal properties when used as a primary optical material in high-power light-emitting diode (LED) units. The results obtained reveal problems of excess heat removal from an LED structure, which appear on passing from phosphor binders based on silicone elastomers to glasses, and demonstrate that the phosphor developed in the study is promising for obtaining warm white light.

  15. Red emission generation through highly efficient energy transfer from Ce(3+) to Mn(2+) in CaO for warm white LEDs.

    PubMed

    Feng, Leyu; Hao, Zhendong; Zhang, Xia; Zhang, Liangliang; Pan, Guohui; Luo, Yongshi; Zhang, Ligong; Zhao, Haifeng; Zhang, Jiahua

    2016-01-28

    CaO:Ce(3+),Mn(2+) phosphors with various Mn(2+) concentrations were synthesized by a solid state reaction method. Efficient energy transfer from Ce(3+) to Mn(2+) was observed and it allows the emission color of CaO:Ce(3+),Mn(2+) to be continuously tuned from yellow (contributed by Ce(3+)) to red (by Mn(2+)) with an increase in Mn(2+) concentration and upon blue light excitation. The red emission becomes dominant when the Mn(2+) concentration is ≥0.014 with an energy transfer efficiency higher than 87% which can reach as high as 94% for a Mn(2+) concentration of only 0.02. A critical distance of 10.5 Å for the Ce(3+)-Mn(2+) energy transfer was determined. A faster decrease of Ce(3+) luminescence intensity in comparison with its lifetime was observed on increasing the Mn(2+) concentration. The analysis of this feature reveals that the Ce(3+) excitation energy can be completely transferred to Mn(2+) if the Ce(3+)-Mn(2+) distance is shorter than 7.6 Å. A warm white LED was fabricated through integrating an InGaN blue LED chip and a blend of two phosphors (YAG:Ce(3+) yellow phosphor and CaO:0.007Ce(3+),0.014Mn(2+) red phosphor) into a single package, which has CIE chromaticity coordinates of (x = 0.37, y = 0.35), a correlated color temperature of 3973 K and a color rendering index of 83.1. The results indicate that CaO:Ce(3+),Mn(2+) may serve as a potential red phosphor for blue LED based warm white LEDs. PMID:26678301

  16. Similar Responses of Circulating MicroRNAs to Acute High-Intensity Interval Exercise and Vigorous-Intensity Continuous Exercise

    PubMed Central

    Cui, Shu F.; Wang, Cheng; Yin, Xin; Tian, Dong; Lu, Qiu J.; Zhang, Chen Y.; Chen, Xi; Ma, Ji Z.

    2016-01-01

    High-intensity interval exercise (HIIE) has been reported to be more beneficial for physical adaptation than low-to-moderate exercise intensity. Recently, it is becoming increasingly evident that circulating miRNAs (c-miRNAs) may distinguish between specific stress signals imposed by variations in the duration, modality, and type of exercise. The aim of this study is to investigate whether or not HIIE is superior to vigorous-intensity continuous exercise (VICE), which is contributing to develop effective fitness assessment. Twenty-six young males were enrolled, and plasma samples were collected prior to exercise and immediately after HIIE or distance-matched VICE. The miRNA level profiles in HIIE were initially determined using TaqMan Low Density Array (TLDA). And the differentially miRNAs levels were validated by stem-loop quantitative reverse-transcription PCR (RT-qPCR). Furthermore, these selective c-miRNAs were measured for VICE. Our results showed that some muscle-related miRNAs levels in the plasma, such as miR-1, miR-133a, miR-133b, and miR-206 significantly increased following HIIE or VICE compared to those at rest (P < 0.05), and there was only a significant reduction in miR-1 level for HIIE compared to VICE (P < 0.05), while no significant differences were observed for other muscle-related miRNAs between both exercises (P > 0.05). In addition, some tissue-related or unknown original miRNA levels, such as miR-485-5p, miR-509-5p, miR-517a, miR-518f, miR-520f, miR-522, miR-553, and miR-888, also significantly increased (P < 0.05) in both exercises compared to rest. However, no significant differences were found between both exercises (P > 0.05). Overall, endurance exercise assessed in this study both led to significant increases in selective c-miRNAs of comparable magnitude, suggesting that both types of endurance exercise have general stress processes. Accordingly, the similar responses to both acute exercises likely indicate both exercises can be used

  17. Similar Responses of Circulating MicroRNAs to Acute High-Intensity Interval Exercise and Vigorous-Intensity Continuous Exercise.

    PubMed

    Cui, Shu F; Wang, Cheng; Yin, Xin; Tian, Dong; Lu, Qiu J; Zhang, Chen Y; Chen, Xi; Ma, Ji Z

    2016-01-01

    High-intensity interval exercise (HIIE) has been reported to be more beneficial for physical adaptation than low-to-moderate exercise intensity. Recently, it is becoming increasingly evident that circulating miRNAs (c-miRNAs) may distinguish between specific stress signals imposed by variations in the duration, modality, and type of exercise. The aim of this study is to investigate whether or not HIIE is superior to vigorous-intensity continuous exercise (VICE), which is contributing to develop effective fitness assessment. Twenty-six young males were enrolled, and plasma samples were collected prior to exercise and immediately after HIIE or distance-matched VICE. The miRNA level profiles in HIIE were initially determined using TaqMan Low Density Array (TLDA). And the differentially miRNAs levels were validated by stem-loop quantitative reverse-transcription PCR (RT-qPCR). Furthermore, these selective c-miRNAs were measured for VICE. Our results showed that some muscle-related miRNAs levels in the plasma, such as miR-1, miR-133a, miR-133b, and miR-206 significantly increased following HIIE or VICE compared to those at rest (P < 0.05), and there was only a significant reduction in miR-1 level for HIIE compared to VICE (P < 0.05), while no significant differences were observed for other muscle-related miRNAs between both exercises (P > 0.05). In addition, some tissue-related or unknown original miRNA levels, such as miR-485-5p, miR-509-5p, miR-517a, miR-518f, miR-520f, miR-522, miR-553, and miR-888, also significantly increased (P < 0.05) in both exercises compared to rest. However, no significant differences were found between both exercises (P > 0.05). Overall, endurance exercise assessed in this study both led to significant increases in selective c-miRNAs of comparable magnitude, suggesting that both types of endurance exercise have general stress processes. Accordingly, the similar responses to both acute exercises likely indicate both exercises can be used

  18. Molecular Ionization at High Intensities: Characterizing OPA Laser Pulses

    NASA Astrophysics Data System (ADS)

    McAcy, Collin; Karnemaat, Ryan; Marsh, Skyler; Foote, David; Uiterwaal, Cornelis

    2012-06-01

    Ultrashort laser pulses have long been the primary instruments of probing and analyzing intense-field molecular dynamics on femtosecond timescales. In particular, processes involving resonance-enhanced multiphoton ionization (REMPI) have provided insight into ionization and dissociation dynamics. Typically the scope of REMPI is limited by the laser properties; namely, REMPI is limited by the transition energies accessible by an integer number of photons. However, the ability to tune the energies of these photons adds flexibility to the available resonances and, for longer wavelengths, makes tunneling the dominant ionization process. Optical parametric amplification (OPA) provides these changes, but the nonlinear processes required for OPA could have complicating effects on pulse duration and focusability, distorting beam quality and compromising experiments. We present the parametric amplification of 800-nm, 50-fs laser pulses in a TOPAS-C system: we use autocorrelation, power measurements, and knife-edging techniques to determine output pulse duration, intensity, and focal characteristics as a function of wavelength. We also report on the effects such changes will have on the practicality of various techniques requiring high-intensity processes.

  19. A Peer-Led High School Transition Program Increases Graduation Rates among Latino Males

    ERIC Educational Resources Information Center

    Johnson, Valerie L.; Simon, Patricia; Mun, Eun-Young

    2014-01-01

    The authors investigated the impact of a manualized high school transition program, the Peer Group Connection (PGC) program, on the graduation rate at a low-income, Mid-Atlantic high school. The program utilized 12th-grade student peer leaders to create a supportive environment for incoming ninth-grade students. Results of a randomized control…

  20. Core-halo issues for a very high intensity beam

    SciTech Connect

    Nghiem, P. A. P.; Chauvin, N.; Uriot, D.

    2014-02-17

    The relevance of classical parameters like beam emittance and envelope used to describe a particle beam is questioned in case of a high intensity accelerator. In the presence of strong space charge effects that affect the beam differently following its density, the much less dense halo part behaves differently from the much denser core part. A method for precisely determining the core-halo limit is proposed, that allows characterizing the halo and the core independently. Results in 1D case are given and discussed. Expected developments extending the method to 2D, 4D, or 6D phase spaces are examined.

  1. High intensity positron beam and angular correlation experiments at Livermore

    SciTech Connect

    Howell, R.H.; Rosenberg, I.J.; Meyer, P.; Fluss, M.J.

    1985-03-01

    A positron beam apparatus that produces a variable energy positron beam with sufficient intensity to perform new positron experiments in an ultrahigh vacuum environment has been installed at the Lawrence Livermore 100 MeV electron linac. We have installed two large area position sensitive gamma-ray detectors to measure angular correlations in two dimensions and a separate highly collimated detector to measure positronium energy distributions by time-of-flight velocity determination. Data from measurements on single crystals of Cu will be described.

  2. Beam instrumentation for future high intense hadron accelerators at Fermilab

    SciTech Connect

    Wendt, M.; Hu, M.; Tassotto, G.; Thurman-Keup, R.; Scarpine, V.; Shin, S.; Zagel, J.; /Fermilab

    2008-08-01

    High intensity hadron beams of up to 2 MW beam power are a key element of new proposed experimental facilities at Fermilab. Project X, which includes a SCRF 8 GeV H{sup -} linac, will be the centerpiece of future HEP activities in the neutrino sector. After a short overview of this, and other proposed projects, we present the current status of the beam instrumentation activities at Fermilab with a few examples. With upgrades and improvements they can meet the requirements of the new beam facilities, however design and development of new instruments is needed, as shown by the prototype and conceptual examples in the last section.

  3. ELECTRON COUD DYNAMICS IN HIGH-INTENSITY RINGS.

    SciTech Connect

    WANG, L.; WEI, J.

    2005-05-16

    Electron cloud due to beam-induced multipacting is one of the main concerns for the high intensity. Electrons generated and accumulated inside the beam pipe form an ''electron cloud'' that interacts with the circulating charged particle beam. With sizeable amount of electrons, this interaction can cause beam instability, beam loss and emittance growth. At the same time, the vacuum pressure will rise due to electron desorption. This talk intends to provide an overview of the mechanism and dynamics of the typical electron multipacting in various magnetic fields and mitigation measures with different beams.

  4. CW high intensity non-scaling FFAG proton drivers

    SciTech Connect

    Johnstone, C.; Berz, M.; Makino, K.; Snopok, P.; /IIT, Chicago

    2011-04-01

    Accelerators are playing increasingly important roles in basic science, technology, and medicine including nuclear power, industrial irradiation, material science, and neutrino production. Proton and light-ion accelerators in particular have many research, energy and medical applications, providing one of the most effective treatments for many types of cancer. Ultra high-intensity and high-energy (GeV) proton drivers are a critical technology for accelerator-driven sub-critical reactors (ADS) and many HEP programs (Muon Collider). These high-intensity GeV-range proton drivers are particularly challenging, encountering duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotrons; a 10-20 MW proton driver is not presently considered technically achievable with conventional re-circulating accelerators. One, as-yet, unexplored re-circulating accelerator, the Fixed-field Alternating Gradient, or FFAG, is an attractive alternative to the cyclotron. Its strong focusing optics are expected to mitigate space charge effects, and a recent innovation in design has coupled stable tunes with isochronous orbits, making the FFAG capable of fixed-frequency, CW acceleration, as in the classical cyclotron. This paper reports on these new advances in FFAG accelerator technology and references advanced modeling tools for fixed-field accelerators developed for and unique to the code COSY INFINITY.

  5. Transcranial Clot Lysis Using High Intensity Focused Ultrasound

    NASA Astrophysics Data System (ADS)

    Hölscher, Thilo; Zadicario, Eyal; Fisher, David J.; Bradley, William G.

    2010-03-01

    Stroke is the third common cause of death worldwide. The majority of strokes are caused by sudden vessel occlusion, due to a blood clot. Vessel recanalization is the primary goal of all acute stroke treatment strategies. Initial data using ultrasound in combination with a therapeutic agent for clot lysis in stroke are promising. However, sound absorption and defocusing of the ultrasound beam occur during transskull insonation, limiting the efficiency of this approach to high extent. Using a transskull High Intensity Focused Ultrasound (HIFU) head system we were able to lyse blood clots within seconds and in absence of further lytic agents. We could show that any correction for the distortion might be negligible to focus the ultrasound beam after transskull insonation. The use of transskull HIFU for immediate clot lysis in the human brain without the need of further drugs and disregarding individual skull bone characteristics could become a successful strategy in early stroke treatment. Using magnetic resonance tomography for neuronavigation MRI Guided High Intensity Focused Ultrasound has the potential to open new avenues for therapeutic applications in the brain including Stroke, Intracranial Hemorrhages, Braintumors, Neurodegenerative Diseases, Thalamic Pain, BBB opening, and local drug delivery. First results in transcranial clot lysis will be presented in this paper.

  6. Nanoplasma Formation by High Intensity Hard X-rays

    PubMed Central

    Tachibana, T.; Jurek, Z.; Fukuzawa, H.; Motomura, K.; Nagaya, K.; Wada, S.; Johnsson, P.; Siano, M.; Mondal, S.; Ito, Y.; Kimura, M.; Sakai, T.; Matsunami, K.; Hayashita, H.; Kajikawa, J.; Liu, X.-J.; Robert, E.; Miron, C.; Feifel, R.; Marangos, J. P.; Tono, K.; Inubushi, Y.; Yabashi, M.; Son, S.-K.; Ziaja, B.; Yao, M.; Santra, R.; Ueda, K.

    2015-01-01

    Using electron spectroscopy, we have investigated nanoplasma formation from noble gas clusters exposed to high-intensity hard-x-ray pulses at ~5 keV. Our experiment was carried out at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility in Japan. Dedicated theoretical simulations were performed with the molecular dynamics tool XMDYN. We found that in this unprecedented wavelength regime nanoplasma formation is a highly indirect process. In the argon clusters investigated, nanoplasma is mainly formed through secondary electron cascading initiated by slow Auger electrons. Energy is distributed within the sample entirely through Auger processes and secondary electron cascading following photoabsorption, as in the hard x-ray regime there is no direct energy transfer from the field to the plasma. This plasma formation mechanism is specific to the hard-x-ray regime and may, thus, also be important for XFEL-based molecular imaging studies. In xenon clusters, photo- and Auger electrons contribute more significantly to the nanoplasma formation. Good agreement between experiment and simulations validates our modelling approach. This has wide-ranging implications for our ability to quantitatively predict the behavior of complex molecular systems irradiated by high-intensity hard x-rays. PMID:26077863

  7. High Intensity Focused Ultrasound Tumor Therapy System and Its Application

    NASA Astrophysics Data System (ADS)

    Sun, Fucheng; He, Ye; Li, Rui

    2007-05-01

    At the end of last century, a High Intensity Focused Ultrasound (HIFU) tumor therapy system was successfully developed and manufactured in China, which has been already applied to clinical therapy. This article aims to discuss the HIFU therapy system and its application. Detailed research includes the following: power amplifiers for high-power ultrasound, ultrasound transducers with large apertures, accurate 3-D mechanical drives, a software control system (both high-voltage control and low-voltage control), and the B-mode ultrasonic diagnostic equipment used for treatment monitoring. Research on the dosage of ultrasound required for tumour therapy in multiple human cases has made it possible to relate a dosage formula, presented in this paper, to other significant parameters such as the volume of thermal tumor solidification, the acoustic intensity (I), and the ultrasound emission time (tn). Moreover, the HIFU therapy system can be applied to the clinical treatment of both benign and malignant tumors in the pelvic and abdominal cavity, such as uterine fibroids, liver cancer and pancreatic carcinoma.

  8. Electrodeless HID lamp study. Final report. [High intensity discharge

    SciTech Connect

    Anderson, J.M.; Johnson, P.D.; Jones, C.E.; Rautenberg, T.H.

    1985-01-01

    High intensity discharge lamps excited by solenoidal electric fields (SEF/HID) were examined for their ability to give high brightness, high efficacy and good color. Frequency of operation was 13.56 MHz (ISM Band) and power to the lamp plasma ranged from about 400 to 1000 W. Radio frequency transformers with air cores and with air core complemented by ferrite material in the magnetic path were used to provide the voltage for excitation. Electrical properties of the matching network and the lamp plasma were measured or calculated and total light from the lamp was measured by an integrating sphere. Efficacies calculated from measurement were found to agree well with the positive column efficacies of conventional HID lamps containing only mercury, and with additives of sodium, thallium, and scandium iodide. Recommendations for future work are given.

  9. Student-Led Project Teams: Significance of Regulation Strategies in High- and Low-Performing Teams

    ERIC Educational Resources Information Center

    Ainsworth, Judith

    2016-01-01

    We studied group and individual co-regulatory and self-regulatory strategies of self-managed student project teams using data from intragroup peer evaluations and a postproject survey. We found that high team performers shared their research and knowledge with others, collaborated to advise and give constructive criticism, and demonstrated moral…

  10. The Effectiveness of Peer-Led FAS/FAE Prevention Presentations in Middle and High Schools

    ERIC Educational Resources Information Center

    Boulter, Lyn

    2007-01-01

    Pregnant women and women who might become pregnant, including middle school- and high school-age adolescents, continue to consume alcohol, placing themselves at risk of having a child with the effects of prenatal alcohol exposure. However, most prevention programs that attempt to increase public awareness and knowledge of FAS and related disorders…

  11. Challenges of PIC Simulations at High Laser Intensity

    NASA Astrophysics Data System (ADS)

    Luedtke, Scott V.; Arefiev, Alexey V.; Toncian, Toma; Hegelich, Bjorn Manuel

    2015-11-01

    New lasers with very high intensity pulses (I >1022 W/cm2) are being commissioned to explore new regimes of laser-matter interactions. These lasers require accurate particle-in-cell (PIC) simulations, which may require new computational approaches to efficiently produce physically accurate results. We examine the constraints on PIC simulations at high field intensity imposed by both the particle pusher and field solver. As proposed by Arefiev, et al. (Physics of Plasmas 22, 013103 (2015)), we implement adaptive sub-cycling in the Boris pusher of the EPOCH code and demonstrate its effectiveness in efficiently reducing errors from the pusher. It is well know that the use of a finite-difference scheme also modifies the electromagnetic wave dispersion relation. We examine the effect of the resulting discrepancy in the phase velocity on electron acceleration, and demonstrate that relatively small errors in the phase velocity lead to substantial changes in the electron energy gain from the laser pulse. We discuss the corresponding conditions for the field solver. These results are relevant to direct laser acceleration and underdense ionization experiments. This work was supported by NNSA cooperative agreement DE-NA0002008, the Defense Advanced Research Projects Agency's PULSE program (12-63-PULSE-FP014) and the Air Force Office of Scientific Research (FA9550-14-1-0045).

  12. High-intensity inspiratory muscle training in COPD.

    PubMed

    Hill, K; Jenkins, S C; Philippe, D L; Cecins, N; Shepherd, K L; Green, D J; Hillman, D R; Eastwood, P R

    2006-06-01

    The aim of the present study was to investigate the effects of an interval-based high-intensity inspiratory muscle training (H-IMT) programme on inspiratory muscle function, exercise capacity, dyspnoea and health-related quality of life (QoL) in subjects with chronic obstructive pulmonary disease. A double-blind randomised controlled trial was performed. Sixteen subjects (11 males, mean forced expiratory volume in one second (FEV(1)) 37.4+/-12.5%) underwent H-IMT performed at the highest tolerable inspiratory threshold load (increasing to 101% of baseline maximum inspiratory pressure). Seventeen subjects (11 males, mean FEV(1 )36.5+/-11.5%) underwent sham inspiratory muscle training (S-IMT) at 10% of maximum inspiratory pressure. Training took place three times a week for 8 weeks and was fully supervised. Pre- and post-training measurements of lung function, maximum inspiratory pressure, maximum threshold pressure, exercise capacity, dyspnoea and QoL (Chronic Respiratory Disease Questionnaire; CRDQ) were obtained. H-IMT increased maximum inspiratory pressure by 29%, maximum threshold pressure by 56%, 6-min walk distance by 27 m, and improved dyspnoea and fatigue (CRDQ) by 1.4 and 0.9 points per item, respectively. These changes were significantly greater than any seen following S-IMT. In conclusion, high-intensity inspiratory muscle training improves inspiratory muscle function in subjects with moderate-to-severe chronic obstructive pulmonary disease, yielding meaningful reductions in dyspnoea and fatigue. PMID:16772388

  13. Photodetachment of H- from intense, short, high-frequency pulses

    NASA Astrophysics Data System (ADS)

    Shao, Hua-Chieh; Robicheaux, F.

    2016-05-01

    We study the photodetachment of an electron from the hydrogen anion due to short, high-frequency laser pulses by numerically solving the time-dependent Schrödinger equation. Simulations are performed to investigate the dependence of the photoelectron spectra on the duration, chirp, and intensity of the pulses. Specifically, we concentrate on the low-energy distributions in the spectra that result from the Raman transitions of the broadband pulses. Contrary to the one-photon ionization, the low-energy distribution maintains a similar width as the laser bandwidth is expanded by chirping the pulses. In addition, we study the transitions of the ionization dynamics from the perturbative to strong-field regime. At high intensities, the positions of the net one- and two-photon absorption peaks in the spectrum shifts and the peaks split to multiple subpeaks because of the multiphoton effects. Moreover, although the one- and two-photon peaks and low-energy distribution exhibit saturation of the ionization yields, the latter shows relatively mild saturation. This work has been supported by DOE under Award No. DE-SC0012193.

  14. Free-field propagation of high intensity noise. [supersonic jets

    NASA Technical Reports Server (NTRS)

    Mcdaniel, O. H.; Roth, S. D.; Welz, J. P.

    1981-01-01

    Research on high intensity (finite amplitude) acoustic waves shows that nonlinear distortion effects generally result in a shift of energy to higher frequencies. The higher intensities associated with supersonic jets would therefore indicate that high frequency enhancement of the spectrum should occur, resulting in the differences observed between subsonic and supersonic jets. A 10,000 acoustic watt source installed in an anechoic chamber generates sound levels such that acoustic shocks are readily observable. Dual frequency excitation of the source produces a strong parametric effect with a difference frequency comparable in level to the primary frequency. The test set up and recording equipment being used to determine the finite amplitude noise representative of an actual supersonic jet are described as well as the development of a computer program based on Burger's equation. The spectra of 1/2 octave band, 1 kHz sine wave, and dual frequency input and output are presented in graphs along with waveforms at Z = .025, 0.1, and 1.0.

  15. Photodetachment of H- from intense, short, high-frequency pulses

    NASA Astrophysics Data System (ADS)

    Shao, Hua-Chieh; Robicheaux, F.

    2016-05-01

    We study the photodetachment of an electron from the hydrogen anion due to short, high-frequency laser pulses by numerically solving the time-dependent Schrödinger equation. Simulations are performed to investigate the dependence of the photoelectron spectra on the duration, chirp, and intensity of the pulses. Specifically, we concentrate on the low-energy distributions in the spectra that result from the Raman transitions of the broadband pulses. Contrary to one-photon ionization, the low-energy distribution maintains an almost constant width as the laser bandwidth is expanded by chirping the pulses. In addition, we study the transitions of the ionization dynamics from the perturbative to the strong-field regime. At high intensities, the positions of the net one- and two-photon absorption peaks in the spectrum shift and the peaks split to multiple subpeaks due to multiphoton effects. Moreover, although the one- and two-photon peaks and low-energy distribution exhibit saturation of the ionization yields, the low-energy distribution shows relatively mild saturation.

  16. Formation of a high intensity low energy positron string

    NASA Astrophysics Data System (ADS)

    Donets, E. D.; Donets, E. E.; Syresin, E. M.; Itahashi, T.; Dubinov, A. E.

    2004-05-01

    The possibility of a high intensity low energy positron beam production is discussed. The proposed Positron String Trap (PST) is based on the principles and technology of the Electron String Ion Source (ESIS) developed in JINR during the last decade. A linear version of ESIS has been used successfully for the production of intense highly charged ion beams of various elements. Now the Tubular Electron String Ion Source (TESIS) concept is under study and this opens really new promising possibilities in physics and technology. In this report, we discuss the application of the tubular-type trap for the storage of positrons cooled to the cryogenic temperatures of 0.05 meV. It is intended that the positron flux at the energy of 1-5 eV, produced by the external source, is injected into the Tubular Positron Trap which has a similar construction as the TESIS. Then the low energy positrons are captured in the PST Penning trap and are cooled down because of their synchrotron radiation in the strong (5-10 T) applied magnetic field. It is expected that the proposed PST should permit storing and cooling to cryogenic temperature of up to 5×109 positrons. The accumulated cooled positrons can be used further for various physics applications, for example, antihydrogen production.

  17. System and method that suppresses intensity fluctuations for free space high-speed optical communication

    DOEpatents

    Berman, Gennady P.; Bishop, Alan R.; Nguyen, Dinh C.; Chernobrod, Boris M.; Gorshkov, Vacheslav N.

    2009-10-13

    A high-speed (Gbps), free space optical communication system is based on spectral encoding of radiation from a wide band light source, such as a laser. By using partially coherent laser beams in combination with a relatively slow photosensor, scintillations can be suppressed by orders of magnitude for distances of more than 10 km. To suppress the intensity fluctuations due to atmospheric turbulence, a source with partial transverse coherence in combination with slow response time photodetector is used. Information is encoded in the spectral domain of a wideband optical source by modulation of spectral amplitudes. A non-coherent light source with wide spectrum (an LED, for example) may be used for high-speed communication over short (less than about a mile) distances.

  18. High repetition rate relativistic electron beam generation from intense laser solid interactions

    NASA Astrophysics Data System (ADS)

    Batson, Thomas; Nees, John; Hou, Bixue; Thomas, Alexander; Krushelnick, Karl

    2014-10-01

    Relativistic electron beams have wide-ranging applications in medicine, materials science, and homeland security. Recent advances in short pulse laser technology have enabled the production of very high focused intensities at kHz rep rates. Consequently this has led to the generation of high flux sources of relativistic electrons - which is a necessary characteristic of these laser plasma sources for any potential application. In our experiments, through the generation of a plasma by focusing a 5 × 1018 W/cm2, 500 Hz, Ti:Sapphire laser pulse onto a fused silica target, we have measured electrons ejected from the target surface having energies in excess of an MeV. The spectrum of these electrons, as well as the spatial divergence of the resulting beam, was also measured with respect to incident laser angle, prepulse timing and focusing conditions. The experimental results are compared to particle in cell simulations.

  19. Ultra-High Intensity Magnetic Field Generation in Dense Plasma

    SciTech Connect

    Fisch, Nathaniel J

    2014-01-08

    I. Grant Objective The main objective of this grant proposal was to explore the efficient generation of intense currents. Whereasthefficient generation of electric current in low-­energy-­density plasma has occupied the attention of the magnetic fusion community for several decades, scant attention has been paid to carrying over to high-­energy-­density plasma the ideas for steady-­state current drive developed for low-­energy-­density plasma, or, for that matter, to inventing new methodologies for generating electric current in high-­energy-­density plasma. What we proposed to do was to identify new mechanisms to accomplish current generation, and to assess the operation, physics, and engineering basis of new forms of current drive in regimes appropriate for new fusion concepts.

  20. High-Intensity Focused Ultrasound Treatment for Advanced Pancreatic Cancer

    PubMed Central

    Zhou, Yufeng

    2014-01-01

    Pancreatic cancer is under high mortality but has few effective treatment modalities. High-intensity focused ultrasound (HIFU) is becoming an emerging approach of noninvasively ablating solid tumor in clinics. A variety of solid tumors have been tried on thousands of patients in the last fifteen years with great success. The principle, mechanism, and clinical outcome of HIFU were introduced first. All 3022 clinical cases of HIFU treatment for the advanced pancreatic cancer alone or in combination with chemotherapy or radiotherapy in 241 published papers were reviewed and summarized for its efficacy, pain relief, clinical benefit rate, survival, Karnofsky performance scale (KPS) score, changes in tumor size, occurrence of echogenicity, serum level, diagnostic assessment of outcome, and associated complications. Immune response induced by HIFU ablation may become an effective way of cancer treatment. Comments for a better outcome and current challenges of HIFU technology are also covered. PMID:25053938

  1. Characteristics of High Staff Intensive Medicare Psychiatric Inpatients

    PubMed Central

    Cromwell, Jerry; Maier, Jan; Gage, Barbara; Drozd, Edward; Osber, Deborah; Richter, Erin; Greenwald, Leslie; Goldman, Howard

    2004-01-01

    Previous analyses of the costs of Medicare psychiatric inpatients have been limited by the use of claims and provider cost reports that fail to quantify differences in patient characteristics and routine costs. This article uses new primary data from 66 psychiatric inpatient units in 40 facilities nationwide to measure the times staff spend in therapeutic and other activities caring for Medicare patients. Patient days are divided into two groups of very high and low staff intensity and patient characteristics compared in each group. Results identify key patient characteristics associated with high staffing days, including old age, dementia and cognitive impairment, severe psychiatric diagnosis, deficits in activities of daily living (ADLs), and assaultive or agitated behaviors. Policy implications and suggested enhancements are made with regard to the proposed CMS case-mix classification system based on claims data alone. PMID:15776703

  2. Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries

    SciTech Connect

    Cooper, Kristie L.; Wang, Anbo; Pickrell, Gary R.

    2006-11-14

    This report summarizes technical progress during the program “Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries”, performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The objective of this program was to use technology recently invented at Virginia Tech to develop and demonstrate the application of self-calibrating optical fiber temperature and pressure sensors to several key energy-intensive industries where conventional, commercially available sensors exhibit greatly abbreviated lifetimes due primarily to environmental degradation. A number of significant technologies were developed under this program, including • a laser bonded silica high temperature fiber sensor with a high temperature capability up to 700°C and a frequency response up to 150 kHz, • the world’s smallest fiber Fabry-Perot high temperature pressure sensor (125 x 20 μm) with 700°C capability, • UV-induced intrinsic Fabry-Perot interferometric sensors for distributed measurement, • a single crystal sapphire fiber-based sensor with a temperature capability up to 1600°C. These technologies have been well demonstrated and laboratory tested. Our work plan included conducting major field tests of these technologies at EPRI, Corning, Pratt & Whitney, and Global Energy; field validation of the technology is critical to ensuring its usefulness to U.S. industries. Unfortunately, due to budget cuts, DOE was unable to follow through with its funding commitment to support Energy Efficiency Science Initiative projects and this final phase was eliminated.

  3. Recent developments for high-intensity proton linacs

    SciTech Connect

    Wangler, T.P.; Garnett, R.W.; Gray, E.R.; Nath, S.

    1996-04-01

    High-intensity proton linacs are being proposed for new projects around the world, especially for tritium production, and for pulsed spallation neutron sources. Typical requirements for these linacs include peak beam current of about 100 mA, and final energies of 1 GeV and higher, APT, a tritium production linac, requires cw operation to obtain sufficient average tritium production linac, requires cw operation to obtain sufficient average beam power, and H{sup +} ion sources appear capable of providing the required current and emittances. The pulsed spallation neutron source requires a linac as an injector to one or more accumulator rings, and favors the use of an H{sup minus} beam to allow charge-exchange injection into the rings. For both applications high availability is demanded; the fraction of scheduled beam time for actual production must be 75% or more. Such a high availability requires low beam-loss to avoid radioactivation of the accelerator, and to allow hands-on maintenance that will keep the mean repair and maintenance times short. To keep the accelerator activation sufficiently low, the beam loss should not exceed about 0.1 to 1.0 nA/m, except perhaps for a few localized places, where special design adaptations could be made. The requirement of such small beam losses at such a high intensity presents a new beam physics challenge. This challenge will require greater understanding of the beam distribution, including the low- density beam halo, which is believed to be responsible for most of the beam losses. Furthermore, it will be necessary to choose the apertures so the beam losses will be acceptably low, and because large aperture size is generally accompanied by an economic penalty resulting from reduced power efficiency, an optimized choice of the aperture will be desirable.

  4. Production of high intensity Beta beams at the ISOLDE facility

    NASA Astrophysics Data System (ADS)

    Hodák, Rastislav; Stora, Thierry; Mendonça, Tania M.

    2011-12-01

    We discuss a design study devoted to a construction of the Beta beams facility at CERN, a next generation European facility aiming for a production of pure and collimated ultra-relativistic beam of electron (anti)neutrinos with help of accelerated β-decaying radioactive ions circulating in a storage decay ring. This high intense source of (anti)neutrinos directed towards a remote underground neutrino detector will allow to measure neutrino oscillations with high accuracy offering a unique chance for establishing a value of the β13 mixing angle and CP violating phase. Recently, a significant progress have been achieved on the conceptual design of high power targets required for a production and an extraction of two baseline isotopes, 6He and 18Ne, at the unexampled rate of several 1013 ions/s. There is a possibility to produce these isotopes using the so-called Isotope Separation On Line (ISOL) method at the ISOLDE facility (CERN). The 6He production is realized by taking advantage of the 9Be(n,α)6He reaction and with help of spallation neutrons and porous BeO target material. The production of 18Ne through the 19F(p,2n)18Ne reaction at required intensities is even more challenging. Currently, a molten salt (NaF) loop target is proposed for a production of high rate of 18Ne required for the Beta beams project. The progress on the design study associated with new data and plans for future is briefly presented.

  5. Extremely high current density over 1000 A/cm2 operation in M-GaN LEDs on bulk GaN substrates with low-efficiency droop

    NASA Astrophysics Data System (ADS)

    Yokogawa, Toshiya; Inoue, Akira

    2014-02-01

    A high current density over 1000 A/cm2 operation in small chip size m-plane GaN-LED has been successfully demonstrated. The LED with chip size 450 × 450 μm2 has emitted 1353 mW in light output power and 39.2% in external quantum efficiency (EQE) at 1000 A/cm2 (1134 mA). The m-plane GaN-LED has showed asymmetric radiation characteristics. The radiation patterns are controlled by the surface of LED package, the height of LED chip, and striped texture on top m-plane surface.

  6. Plasmas and Short-Pulse, High-Intensity Lasers

    NASA Astrophysics Data System (ADS)

    Clark, Thomas

    1999-11-01

    Many of the applications of short-pulse, high-intensity laser systems, including coherent UV and X-ray generation, compact particle accelerators, and non-perturbative nonlinear optics as well as the study of laser-matter interaction physics, require large intensity-interaction length products. In recent years, plasma structures resulting from the hydrodynamic evolution of laser-produced plasma filaments have proven to be attractive media for guiding pulses with peak powers approaching the terawatt level over lengths many times the vacuum Rayleigh range. The hydrodynamics of plasma waveguides have been characterized using time- and space-resolved interferometry measurements of electron density profiles. The laser-driven ionization and heating phase of the plasma filament creation is followed by hot electron driven plasma expansion. Density profiles suitable for optical guiding develop within the first few hundred picoseconds after plasma creation, during which rapid cooling occurs. At longer times the plasma expansion closely follows that of a cylindrical blast wave, with further cooling due to expansion work. The observed guided intensity profiles of end-coupled and tunnel-coupled pulses compare favorably with calculations of the quasi-bound waveguide modes based on the measured electron density profiles. Time- and space-resolved electron density measurements of a laser-driven concentric implosion were also performed. The implosion is the result of the interaction of a second laser pulse with an existing plasma waveguide. The two-pulse absorption and ionization significantly exceed that due to a single pulse of the same total energy. The author would like to acknowledge the significant contributions of Prof. Howard M. Milchberg to the work being presented.

  7. Design Aspects of Focal Beams From High-Intensity Arrays

    PubMed Central

    Stephens, Douglas N.; Kruse, Dustin E.; Qin, Shengping; Ferrara, Katherine W.

    2011-01-01

    As the applications of ultrasonic thermal therapies expand, the design of the high-intensity array must address both the energy delivery of the main beam and the character and relevance of off-target beam energy. We simulate the acoustic field performance of a selected set of circular arrays organized by array format, including flat versus curved arrays, periodic versus random arrays, and center void diameter variations. Performance metrics are based on the −3-dB focal main lobe (FML) positioning range, axial grating lobe (AGL) temperatures, and side lobe levels. Using finite-element analysis, we evaluate the relative heating of the FML and the AGLs. All arrays have a maximum diameter of 100λ, with element count ranging from 64 to 1024 and continuous wave frequency of 1.5 MHz. First, we show that a 50% spherical annulus produces focus beam side lobes which decay as a function of lateral distance at nearly 87% of the exponential rate of a full aperture. Second, for the arrays studied, the efficiency of power delivery over the −3-dB focus positioning range for spherical arrays is at least 2-fold greater than for flat arrays; the 256-element case shows a 5-fold advantage for the spherical array. Third, AGL heating can be significant as the focal target is moved to its distal half-intensity depth from the natural focus. Increasing the element count of a randomized array to 256 elements decreases the AGL-to-FML heating ratio to 0.12 at the distal half-intensity depth. Further increases in element count yield modest improvements. A 49% improvement in the AGL-to-peak heating ratio is predicted by using the Sumanaweera spiral element pattern with randomization. PMID:21859578

  8. NASA's New High Intensity Solar Environment Test Capability

    NASA Technical Reports Server (NTRS)

    Schneider, Todd A.; Vaughn, Jason A.; Wright, Kenneth H.

    2012-01-01

    Across the world, new spaceflight missions are being designed and executed that will place spacecraft and instruments into challenging environments throughout the solar system. To aid in the successful completion of these new missions, NASA has developed a new flexible space environment test platform. The High Intensity Solar Environment Test (HISET) capability located at NASA fs Marshall Space Flight Center provides scientists and engineers with the means to test spacecraft materials and systems in a wide range of solar wind and solar photon environments. Featuring a solar simulator capable of delivering approximately 1 MW/m2 of broad spectrum radiation at maximum power, HISET provides a means to test systems or components that could explore the solar corona. The solar simulator consists of three high-power Xenon arc lamps that can be operated independently over a range of power to meet test requirements; i.e., the lamp power can be greatly reduced to simulate the solar intensity at several AU. Integral to the HISET capability are charged particle sources that can provide a solar wind (electron and proton) environment. Used individually or in combination, the charged particle sources can provide fluxes ranging from a few nA/cm2 to 100s of nA/cm2 over an energy range of 50 eV to 100 keV for electrons and 100 eV to 30 keV for protons. Anchored by a high vacuum facility equipped with a liquid nitrogen cold shroud for radiative cooling scenarios, HISET is able to accommodate samples as large as 1 meter in diameter. In this poster, details of the HISET capability will be presented, including the wide ]ranging configurability of the system.

  9. HIGH INTENSITY EFFECTS IN THE SNS ACCUMULATOR RING

    SciTech Connect

    Holmes, Jeffrey A; Cousineau, Sarah M; Danilov, Viatcheslav; Plum, Michael A; Shishlo, Andrei P

    2008-01-01

    Currently operating at 0.5 MW beam power on target, the Spallation Neutron Source (SNS) is already the world's most powerful pulsed neutron source. However, we are only one third of the way to full power. As we ramp toward full power, the control of the beam and beam loss in the ring will be critical. In addition to practical considerations, such as choice of operating point, painting scheme, RF bunching, and beam scattering, it may be necessary to understand and mitigate collective effects due to space charge, impedances, and electron clouds. At each stage of the power ramp-up, we use all available resources to understand and to minimize beam losses. From the standpoint of beam dynamics, the losses observed so far under normal operating conditions have not involved collective phenomena. We are now entering the intensity regime in which this may change. In dedicated high intensity beam studies, we have already observed resistive wall, extraction kicker impedance-driven, and electron cloud activities. The analysis and simulation of this data are important ongoing activities at SNS. This paper discusses the status of this work, as well as other considerations necessary to the successful full power operation of SNS.

  10. Blood coagulation using High Intensity Focused Ultrasound (HIFU)

    NASA Astrophysics Data System (ADS)

    Nguyen, Phuc V.; Oh, Junghwan; Kang, Hyun Wook

    2014-03-01

    High Intensity Focused Ultrasound (HIFU) technology provides a feasible method of achieving thermal coagulation during surgical procedures. One of the potential clinical benefits of HIFU can induce immediate hemostasis without suturing. The objective of this study was to investigate the efficiency of a HIFU system for blood coagulation on severe vascular injury. ngHIFU treatment was implemented immediately after bleeding in artery. The ultrasound probe was made of piezoelectric material, generating a central frequency of 2.0 MHz as well as an ellipsoidal focal spot of 2 mm in lateral dimension and 10 mm in axial dimension. Acoustic coagulation was employed on a perfused chicken artery model in vitro. A surgical incision (1 to 2 mm long) was made with a scapel on the arterial wall, and heparinized autologous blood was made to leak out from the incision with a syringe pump. A total of 5 femoral artery incisions was treated with the HIFU beam. The intensity of 4500 W/cm2 at the focus was applied for all treatments. Complete hemostasis was achieved in all treatments, along with the treatment times of 25 to 50 seconds. The estimated intraoperative blood loss was from 2 to 5 mL. The proposed HIFU system may provide an effective method for immediate blood coagulation for arteries and veins in clinical applications.

  11. High intensity ion beam injection into the 88-inch cyclotron

    SciTech Connect

    Wutte, Daniela; Clark, Dave J.; Laune, Bernard; Leitner,Matthaeus A.; Lyneis, Claude M.

    2000-05-31

    Low cross section experiments to produce super-heavyelements have increased the demand for high intensity heavy ion beams atenergies of about 5 MeV/nucleon at the 88-Inch Cyclotron at the LawrenceBerkeley National Laboratory. Therefore, efforts are underway to increasethe overall ion beam transmission through the axial injection line andthe cyclotron. The ion beam emittance has been measured for various ionmasses and charge states. Beam transport simulations including spacecharge effects were performed for both of the injection line and the ionsource extraction. The relatively low nominal injection voltage of 10 kVwas found to be the main factor for ion beam losses, because of beam blowup due to space charge forces at higher intensities. Consequently,experiments and simulations have been performed at higherinjectionenergies, and it was demonstrated that the ion beams could still becentered in the cyclotron at these energies. Therefore, the new injectorion source VENUS and its ion beam transport system (currently underconstruction at the 88-Inch Cyclotron) are designed for extractionvoltages up to 30 kV.

  12. Synthesis of the phase pure Ba3Si6O12N2:Eu2+ green phosphor and its application in high color rendition white LEDs.

    PubMed

    Li, Wanyuan; Xie, Rong-Jun; Zhou, Tianliang; Liu, Lihong; Zhu, Yuejin

    2014-04-28

    The promising green oxynitride phosphor, Ba3Si6O12N2:Eu(2+), was synthesized at 1350 °C for 5 hours under a reducing N2/H2 (5%) atmosphere by using the solid-state reaction method. The phase purity was investigated by varying the nominal compositions, and the pure phase was achieved by carefully controlling the Si/Ba and O/Ba ratios. The phosphor displayed a broad excitation band spanning from the ultraviolet (UV) to the blue spectral region, and showed a single symmetrical emission band peaking at 525 nm with a full width at half maximum (FWHM) of ∼ 68 nm. The as-prepared green phosphor exhibited a small thermal quenching, which remained 90% of the initial emission intensity when measured at 200 °C. The internal and external quantum efficiencies measured under 450 nm excitation were 68 and 38%, respectively. Color temperature-tunable white LEDs with a high color rendering index of Ra = 88-94 were attained by combining the prepared green phosphor and a red phosphor Sr2Si5N8:Eu(2+) with a blue LED chip. PMID:24557497

  13. Proceedings of the third ICFA mini-workshop on high intensity, high brightness hadron accelerators

    SciTech Connect

    Roser, T.

    1997-11-01

    The third mini-workshop on high intensity, high brightness hadron accelerators was held at Brookhaven National Laboratory on May 7-9, 1997 and had about 30 participants. The workshop focussed on rf and longitudinal dynamics issues relevant to intense and/or bright hadron synchrotrons. A plenary session was followed by four sessions on particular topics. This document contains copies of the viewgraphs used as well as summaries written by the session chairs.

  14. Highly efficient low color temperature organic LED using blend carrier modulation layer

    NASA Astrophysics Data System (ADS)

    Hsieh, Yao-Ching; Chen, Szu-Hao; Shen, Shih-Ming; Wang, Ching-Chiun; Chen, Chien-Chih; Jou, Jwo-Huei

    2012-10-01

    Color temperature (CT) of light has great effect on human physiology and psychology, and low CT light, minimizing melatonin suppression and decreasing the risk of breast, colorectal, and prostate cancer. We demonstrates the incorporation of a blend carrier modulation interlayer (CML) between emissive layers to improve the device performance of low CT organic light emitting diodes, which exhibits an external quantum efficiency of 22.7% and 36 lm W-1 (54 cd A-1) with 1880 K at 100 cd m-2, or 20.8% and 29 lm W-1 (50 cd A-1) with 1940 K at 1000 cd m-2. The result shows a CT much lower than that of incandescent bulbs, which is 2500 K with 15 lmW-1 efficiency, and even as low as that of candles, which is 2000 K with 0.1 lmW-1. The high efficiency of the proposed device may be attributed to its CML, which helps effectively distribute the entering carriers into the available recombination zones.

  15. An Electroless-Ag Reflector Developed for High-Brightness White LEDs

    NASA Astrophysics Data System (ADS)

    Liu, W. C.; Chung, T. Y.; Chen, Y. H.; Hsiao, C. Y.; Lin, C. P.; Liu, C. Y.

    2014-12-01

    This study was conducted to investigate the reflectivity and the reflectivity stability of the electroless (Ag) metallization of reflectors used in high-brightness white GaN light-emitting diode packages. Two main reflector metallization schemes were studied: (1) electroless-Ag/electroless-pure-Pd/electroless-Ni plating and (2) electroless-Ag/electroless-Pd(P)/electroless-Ni plating. The reflectivity achieved using all reflector-metallization schemes was >85% in the visible range. However, in the electroless-Ag/electroless-pure-Pd/electroless-Ni reflector, reflectivity exhibited substantial thermal degradation; this was because of two principal factors: (1) the change in the surface morphology of the electroless-Ag surface grains; and (2) the alloying effect on the Ag layer exerted by the interdiffusion occurring with the underlying Pd layer. In this study, P was added to the Pd layer, and the thermal degradation of the annealed electroless-Ag/electroless-Pd(P)/electroless-Ni reflector was measured to be less than that of the electroless-Ag/electroless-pure-Pd/electroless-Ni reflector. The P content retarded the interdiffusion between the Ag and Pd(P) layers and preserved the faceted surface of the electroless-Ag layer, which enhanced the stability of the reflectivity of the electroless-Ag reflector. Furthermore, increasing the thickness of the electroless-Ag layer reduced the amount of Pd diffusing through the Ag layer, which helped retain the reflectivity of the Ag surface.

  16. High Pressure CPT Signals using Intensity Modulated Light

    NASA Astrophysics Data System (ADS)

    Post, Amber; Jau, Yuan-Yu; Miron, Eli; Romalis, Michael; Kuzma, Nicholas; Happer, William

    2004-05-01

    Coherent Population Trapping (CPT) is a promising technique for use in miniature atomic clocks, since it uses modulated light to detect clock resonances rather than microwaves. This method typically uses frequency-modulated light to probe cells with low buffer gas pressure, in which the ground-state hyperfine structure is clearly resolved. However, conventional frequency-modulated CPT fails at the higher pressures needed to inhibit wall collisions in miniature cells. We present theory and supporting experimental results of high-pressure CPT signals using intensity-modulated light. Circularly polarized light tuned to the Rb D1 line traps most of the atoms in the F=2, m_F=2, where the microwave ``end resonance"^2 is excited. We will show experimental data and briefly discuss linewidth broadening mechanisms. 2 Y.-Y. Jau, A. B. Post, N. N. Kuzma, et al., Phys. Rev. Lett. (in press, 2004).

  17. High intensity neutrino source superconducting solenoid cyrostat design

    SciTech Connect

    Page, T.M.; Nicol, T.H.; Feher, S.; Terechkine, I.; Tompkins, J.; /Fermilab

    2006-06-01

    Fermi National Accelerator Laboratory (FNAL) is involved in the development of a 100 MeV superconducting linac. This linac is part of the High Intensity Neutrino Source (HINS) R&D Program. The initial beam acceleration in the front end section of the linac is achieved using room temperature spoke cavities, each of which is combined with a superconducting focusing solenoid. These solenoid magnets are cooled with liquid helium at 4.5K, operate at 250 A and have a maximum magnetic field strength of 7.5 T. The solenoid cryostat will house the helium vessel, suspension system, thermal shield, multilayer insulation, power leads, instrumentation, a vacuum vessel and cryogenic distribution lines. This paper discusses the requirements and detailed design of these superconducting solenoid cryostats.

  18. High Intensity, Pulsed, D-D Neutron Generator

    NASA Astrophysics Data System (ADS)

    Williams, D. L.; Vainionpaa, J. H.; Jones, G.; Piestrup, M. A.; Gary, C. K.; Harris, J. L.; Fuller, M. J.; Cremer, J. T.; Ludewigt, B. A.; Kwan, J. W.; Reijonen, J.; Leung, K.-N.; Gough, R. A.

    2009-03-01

    Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. These single-beam generators are capable of producing up to 1010 n/s. Previously, Adelphi and LBNL have demonstrated these generators' applications in fast neutron radiography, Prompt Gamma Neutron Activation Analysis (PGNAA) and Neutron Activation Analysis (NAA). Together with an inexpensive compact moderator, these high-output neutron generators extend useful applications to home laboratory operations.

  19. High Intensity, Pulsed, D-D Neutron Generator

    SciTech Connect

    Williams, D. L.; Vainionpaa, J. H.; Jones, G.; Piestrup, M. A.; Gary, C. K.; Harris, J. L.; Fuller, M. J.; Cremer, J. T.; Ludewigt, Bernhard A.; Kwan, J. W.; Reijonen, J.; Leung, K.-N.; Gough, R. A.

    2008-08-01

    Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. These single-beam generators are capable of producing up to 1E10 n/s. Previously, Adelphi and LBNL have demonstrated these generators' applications in fast neutron radiography, Prompt Gamma Neutron Activation Analysis (PGNAA) and Neutron Activation Analysis (NAA). Together with an inexpensive compact moderator, these high-output neutron generators extend useful applications to home laboratory operations.

  20. A Plasma Lens for High Intensity Laser Focusing

    SciTech Connect

    Fang, F.; Clayton, C. E.; Marsh, K. A.; Joshi, C.; Lopes, N. C.; Ito, H.

    2006-11-27

    A plasma lens based on a short hydrogen-filled alumina capillary discharge is experimentally characterized. For a plasma length of about 5mm, the focal length, measured from the plasma entrance, was {approx} 11 to 8mm for on axis densities of {approx} 2.5 to 5 x 1018cm-3, respectively. The plasma temperature away from the walls of the 1/2mm diameter capillary was estimated to be {approx} 8eV indicating that the plasma is fully ionized. Such a lens should thus be suitable for focusing very high intensity pulses. Comparisons of the measured focusing strength to that predicted by a first-order fluid model [N. A. Bobrova, et al., Phys. Rev. E 65, 016407 (2002)] shows reasonable agreement given that some of the observed plasma parameters are not predicted by this model.

  1. S-76 rotorcraft high intensity radiated fields. Test plan

    NASA Astrophysics Data System (ADS)

    Blair, Jerry T.; Brooks, Steve M.; Barnes, Ken A.

    1991-07-01

    Concern over the effects of High Intensity Radiated Fields (HIRF) on civil and military aircraft has increased over the past 10 years. The increase is due to several factors which affect the safe flight of all fixed-wing and rotorcraft. Previous flight-critical mechanical controls are being replaced by electronic computer-driven controls; manufacturers are increasing the use of composite materials in the fabrication of new aircraft; and frequency ranges and output power levels of commercial and military transmitters have significantly increased. While much HIRF susceptibility information has been collected, the data are proprietary and have not been released. To address the HIRF concerns and begin development of a releasable HIRF data base, the FAA Technical Center, has implemented a HIRF research program. As part of that program, a HIRF test was performed on a Sikorsky S-76 Helicopter. The purpose, approach, and initial findings of the S-76 HIRF test are addressed.

  2. Comparison of Two High Intensity Acoustic Test Facilities

    NASA Astrophysics Data System (ADS)

    Launay, A.; Tadao Sakita, M.; Kim, Youngkey K.

    2004-08-01

    In two different countries, at the same period of time, the institutes in charge of the development of space activities have decided to extend their satellite integration and test center, and to implement a reverberant acoustic chamber. In Brazil the INPE laboratory (LIT : Laboratorio de Integracao e Testes) and in South Korea the KARI laboratory (SITC : Satellite Integration and Test Center) started their projects in July 2000 for the RATF (Reverberant Acoustic Test Facility) and in May 2001 for the HIAC (High Intensity Acoustic Chamber) respectively, writing the technical specifications. The kick-off meetings took place in December 2000 and in February 2002 and the opening ceremonies in December 19, 2002 in Brazil and in August 22, 2003 in Korea. This paper compares the two projects in terms of design choices, manufacturing processes, equipment installed and technical final characteristics.

  3. Ion acceleration using high-contrast ultra-intense lasers

    NASA Astrophysics Data System (ADS)

    Fuchs, J.; Antici, P.; D'Humières, E.; Lefebvre, E.; Borghesi, M.; Brambrink, E.; Cecchetti, C.; Toncian, T.; Pépin, H.; Audebert, P.

    2006-06-01

    We have compared the acceleration of high-energy ions from the rear-surface of thin foils for various contrast conditions of the ultra-intense laser pulse irradiating the targets. The experiments were performed using the LULI 100 TW facility. We used Al targets of variable thicknesses and the laser pulse contrast ratio ahead of the main pulse was varied using either a fast Pockels cell or a single or double plasma mirror. The latter was installed at an intermediate field position, in between the focusing optics and the target, so that its effect was optimized. By improving with these two methods the laser pulse contrast, we have observed that we could significantly reduce the thickness of the target used for proton acceleration and at the same time increase both the cut-off energy of the accelerated protons and the energy conversion efficiency of the process.

  4. Optimal conditions for tissue perforation using high intensity focused ultrasound

    NASA Astrophysics Data System (ADS)

    Mochizuki, Takashi; Kihara, Taizo; Ogawa, Kouji; Tanabe, Ryoko; Yosizawa, Shin; Umemura, Shin-ichiro; Kakimoto, Takashi; Yamashita, Hiromasa; Chiba, Toshio

    2012-10-01

    To perforate tissue lying deep part in body, a large size transducer was assembled by combining four spherical-shaped transducers, and the optimal conditions for tissue perforation have studied using ventricle muscle of chicken as a target. The ex vivo experiments showed that ventricle muscle was successfully perforated both when it was exposed to High Intensity Focused Ultrasound (HIFU) directly and when it was exposed to HIFU through atrial muscle layer. Moreover, it was shown that calculated acoustic power distributions are well similar to the perforation patterns, and that the acoustic energy distributes very complexly near the focus. Lastly, perforation on the living rabbit bladder wall was demonstrated as a preliminary in vivo experiment.

  5. [High-intensity interval training for young athletes].

    PubMed

    Engel, Florian Azad; Sperlich, Billy

    2014-06-01

    A computer-based literature research during July 2013 using the electronic databases PubMed, MEDLINE, SPORTDiscus and Web of Science was performed to assess the effect of the high intensity interval training (HIIT) on sport performance in healthy children and adolescents. Studies examining the effect of HIIT on aerobic and anaerobic performance pre and post to HIIT-Interventions in children and adolescents (9-18 years) were included. The results indicate increased aerobic and anaerobic performance following two or three HIIT sessions per week for a period of five to ten weeks, additional to normal training. Results regarding long term effects following HIIT have not been documented so far. In addition, due to the physiological characteris-tics during HIIT protocols improved fatigue resistance has been demonstrated in children as compared to adults, which may be interpreted as a prerequisite for the applicability of HIIT in children. PMID:24733304

  6. High-intensity cyclotron for the IsoDAR experiment

    NASA Astrophysics Data System (ADS)

    Campo, D.; IsoDAR Collaboration

    2015-03-01

    The IsoDAR experiment is the MIT proposal to investigate about several neutrino properties, in order to explain some anomalies experimentally observed. It requires 10mA of proton beam at the energy of 60MeV to produce a high-intensity electron antineutrino flux from the production and the decay of 8Li: it is an ambitious goal for the accelerator design, due also to the fact that the machine has to be placed near a neutrino detector, like KAMLAND or WATCHMAN, located in underground sites. A compact cyclotron able to accelerate H2+ molecule beam up to energy of 60MeV/amu is under study. The critical issues of this machine concern the beam injection due to the effects of space charge, the efficiency of the beam extraction and the technical solutions needed to the machine assembly. Here, the innovative solutions and the preliminary results achieved by the IsoDAR team are discussed.

  7. High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

    NASA Astrophysics Data System (ADS)

    Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

    2014-09-01

    This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

  8. Nitrate supplementation and high-intensity performance in competitive cyclists.

    PubMed

    Hoon, Matthew W; Hopkins, William G; Jones, Andrew M; Martin, David T; Halson, Shona L; West, Nicholas P; Johnson, Nathan A; Burke, Louise M

    2014-09-01

    Consumption of inorganic nitrate (NO3(-)) is known to enhance endurance exercise performance in recreationally trained subjects. Here we report the effect on a high-intensity performance task in national-level cyclists. The performance test consisted of 2 cycle ergometer time trials of 4 min duration with 75 min between trials. In a randomized crossover design, 26 cyclists performed the test under the following 4 conditions (each separated by a 6-day washout): consumption of 70 mL of nitrate-rich beetroot juice at 150 min or 75 min before the first time trial, addition of a 35 mL "top-up dose" following the first time trial in the 150 min condition, and consumption of a placebo. A linear mixed model with adjustments for learning effects and athlete fitness (peak incremental power) was used to estimate effects on mean power, with probabilistic inferences based on a smallest important effect of 1.0%. Peak plasma nitrite (NO2(-)) concentration was greatest when nitrate was taken 75 min before the first time trial. Relative to placebo, the mean effect of all 3 nitrate treatments was unclear in the first time trial (1.3%, 90% confidence limits: ±1.7%), but possibly harmful in the second time trial (-0.3%, ±1.6%). Differences between nitrate treatments were unclear, as was the estimate of any consistent individual response to the treatments. Allowing for sampling uncertainty, the effect of nitrate on performance was less than previous studies. Under the conditions of our experiment, nitrate supplementation may be ineffective in facilitating high-intensity exercise in competitive athletes. PMID:24951296

  9. Frequency conversion of high-intensity, femtosecond laser pulses

    SciTech Connect

    Banks, P S

    1997-06-01

    Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated

  10. LED flicker pulsing

    NASA Astrophysics Data System (ADS)

    Johnson, Mark A.; Cote, Paul J.

    2001-08-01

    There is need to replace hazardous radioluminescent light sources with a means of illumination that is environmentally friendly. This paper describes an electronic source that was developed as a potential candidate to replace low intensity tritium in a military system. It employs an LED for illumination and a 3-volt coin cell battery as a power source. This new light source is electronically invisible, requires minimal maintenance, and provides the lowest practical illumination to preclude detection by optical means. The low intensity requires that the LED be driven at DC current levels resulting in poor luminous efficiency. Therefore, in an effort to maximize battery life, the LED is pulsed into a more optically efficient mode of operation. However, conventional pulsing techniques are not employed because of concerns the electronics could be identified by conspicuous power spectral density (PSD) components in the electromagnetic spectrum generated by a pulsed LED. Therefore, flicker noise concepts have been employed to efficiently drive the LED while generating a virtually undetectable spectral signature. Although ideally the pulse durations, magnitudes, and spacings should be random, a significant reduction in conspicuous PSD components can be achieved when imposing practical constraints. The dominant components of the power spectrum are significantly reduced using fixed pulse durations and magnitudes while varying only the pulse spacing. The mean duty cycle is set to provide the same effective illumination as DC operation while generating a PSD normally associated with natural phenomena.

  11. Operation of the Proto-MPEX High Intensity Plasma Source

    NASA Astrophysics Data System (ADS)

    Caughman, J. B. O.; Goulding, R. H.; Biewer, T. M.; Bigelow, T. S.; Campbell, I. H.; Diem, S. J.; Martin, E. H.; Pesavento, P. V.; Rapp, J.; Ray, H. B.; Shaw, G. C.; Showers, M. A.; Luo, G.-N.

    2015-11-01

    The Prototype Materials Plasma Experiment (Proto-MPEX) is a linear high-intensity rf plasma source that combines a high-density helicon plasma generator with electron and ion heating sections. It is being used to study the physics of heating over-dense plasmas in a linear configuration. The helicon plasma is produced by coupling 13.56 MHz rf power at levels up to 100 kW. Microwaves at 28 GHz (~ 150 kW) are coupled to the electrons in the over-dense helicon plasma via Electron Bernstein Waves (EBW). Ion cyclotron heating (~ 30 kW) will be via a magnetic beach approach. Plasma diagnostics include Thomson Scattering and a retarding field energy analyzer near the target, while a microwave interferometer and double-Langmuir probes are used to determine plasma parameters elsewhere in the system. Filterscopes are being used to measure D-alpha emission and He line ratios at multiple locations, and IR cameras image the target plates to determine heat deposition. High plasma densities in the helicon region have been produced in He (>3x1019/m3) and D (>1.5x1019/m3) , and operation with on-axis magnetic field strength >1 T has been demonstrated. Details of the experimental results and future plans for studying plasma surface/RF antenna interactions will be presented. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  12. Nanobiotechnology promotes noninvasive high-intensity focused ultrasound cancer surgery.

    PubMed

    Chen, Yu; Chen, Hangrong; Shi, Jianlin

    2015-01-01

    The successful cancer eradication in a noninvasive manner is the ultimate objective in the fight against cancer. As a "bloodless scalpel," high-intensity focused ultrasound (HIFU) is regarded as one of the most promising and representative noninvasive therapeutic modalities for cancer surgery. However, large-scale clinical applications of HIFU are still in their infancy because of critical efficiency and safety issues which remain to be solved. Fortunately, recently developed nanobiotechnology provides an alternative efficient approach to improve such important issues in HIFU, especially for cancer therapy. This Research News presents the very recent exciting progresses on the elaborate design and fabrication of organic, inorganic, and organic/inorganic hybrid nanoparticles for enhancing the HIFU ablation efficiency against tumor tissues. It is highly expected that this Research News can arouse more extensive research enthusiasm on the development of functional nanomaterials for highly efficient HIFU-based synergistic therapy, which will give a promising noninvasive therapeutic modality for the successful cancer therapy with minimal damage to surrounding normal tissues, due to the noninvasive and site-specific therapeutic features of HIFU. PMID:24898413

  13. Heavy Ion High Intensity Upgrade of the GSI UNILAC

    SciTech Connect

    Barth, W.; Dahl, L.; Galonska, M.; Glatz, J.; Groening, L.; Hollinger, R.; Richter, S.; Yaramyshev, S.

    2005-06-08

    For the future Facility for Antiproton and Ion Research (FAIR) at Darmstadt the present GSI-accelerator complex, consisting of the linear accelerator UNILAC and the heavy ion synchrotron SIS 18, is foreseen to serve as U28+-injector for up to 1012 particles/s. After a new High Current Injector (HSI) was installed, many different ion species were accelerated in the UNILAC for physics experiments. In 2001 a high energy physics experiment used up to 2{center_dot}109 uranium ions per SIS 18-spill (U73+) while a MEVVA ion source was in routine operation for the first time. In the past two years, different hardware measures and careful fine tuning in all sections of the UNILAC resulted in an increase of the beam intensity to 9.5{center_dot}1010 U27+-ions per 100 {mu}s or 1.5{center_dot}1010 U73+-ions per 100 {mu}s. The contribution reports results of beam measurements during the high current operation with argon and uranium beams (pulse beam power up to 0.5 MW). One of the major tasks was to optimize the beam matching to the Alvarez-DTL. In addition further upgrades, including improved beam diagnostics, are described, which allow to fill the SIS 18 up to its space charge limit (SCL) of 2.7{center_dot}1011 U28+-ions per cycle.

  14. [Research on the Highly Stable White LED with CdSe/ZnS Quantum Dot as Light Conversion Layer].

    PubMed

    Cao, Jin; Zhou, Jie; Xie, Jing-weil; Chen, An-ping; Zhang, Xuel; Yin, Lu-qiao; Zhang, Jian-hua

    2016-02-01

    In accordance with the one-step synthesis, in this paper, we synthesized 510, 550 and 630 nm three emission peaks CdSe/ZnS core-shell quantum dots with high stability and high quantum yield whose quantum yield were 82%, 98% and 97%. We used the quantum dot material to replace the phosphor material, and mixed QDs with the silicone uniformly, then dispersed the QDs/silicone composites onto the blue InGaN LEDs to fabricate the QDs-WLEDs. By successively adding different colors of quantum dots for the preparation of quantum dot light converting layer, We investigated that how does the ratio of the three kind of quantum dots whose peaks were 510, 550 and 630 nm effect on the properties of the white LED devices. This paper also studied the mechanism of energy conversion between different colors of quantum dots. We also utilized the mechanism that the quantum dots effect on the white spectrum and color coordinates; we got the results of the optimization of the white device and the ratio of three-color quantum dots. The results show that when the quantum dot ratio is 24:7:10, white LED devices with high stability and high efficiency can be obtained, in the current range of 20-200 mA, the range of color temperature is from 4 607 to 5 920 K, the CIE-1931 coordinates is from (0.355 1,0.348 3) to (0.323 4, 0.336 1), the color rendering index is from 77. 6 to 84. 2, and the highest power efficiency of the devices achieves to 31.69 lm · W⁻¹ @ 20 mA. In addition, in order to further investigate the reason of stable device performance, We studied the effects of time, temperature, UV treatment on the stability of CdSe/ZnS QDs/silicone light conversion material, the results show that the excellent stability of the devices attributes to the stability of the one-step synthesis of core-shell structure of the quantum dot material, the final optimized device is a low-power high-quality white light source and the device has good application prospects in the field of standard white

  15. Resonant high-order harmonic generation from plasma ablation: Laser intensity dependence of the harmonic intensity and phase

    SciTech Connect

    Milosevic, D. B.

    2010-02-15

    Experimentally observed strong enhancement of a single high-order harmonic in harmonic generation from low-ionized laser plasma ablation is explained as resonant harmonic generation. The resonant harmonic intensity increases regularly with the increase of the laser intensity, while the phase of the resonant harmonic is almost independent of the laser intensity. This is in sharp contrast with the usual plateau and cutoff harmonics, the intensity of which exhibits wild oscillations while its phase changes rapidly with the laser intensity. The temporal profile of a group of harmonics, which includes the resonant harmonic, has the form of a broad peak in each laser-field half cycle. These characteristics of resonant harmonics can have an important application in attoscience. We illustrate our results using examples of Sn and Sb plasmas.

  16. Interaction of High Intensity Electromagnetic Waves with Plasmas

    SciTech Connect

    G. Shvets

    2008-10-03

    The focus of our work during the duration of this grant was on the following areas: (a) the fundamental plasma physics of intense laser-plasma interactions, including the nonlinear excitation of plasma waves for accelerator applications, as well as the recently discovered by us phenomenon of the relativistic bi-stability of relativistic plasma waves driven by a laser beatwave; (b) interaction of high power microwave beams with magnetized plasma, including some of the recently discovered by us phenomena such as the Undulator Induced Transparency (UIT) as well as the new approaches to dynamic manipulation of microwave pulses; (c) investigations of the multi-color laser pulse interactions in the plasma, including the recently discovered by us phenomenon of Electromagnetic Cascading (EC) and the effect of the EC of three-dimensional dynamics of laser pulses (enhanced/suppressed selffocusing etc.); (d) interaction of high-current electron beams with the ambient plasma in the context of Fast Ignitor (FI) physics, with the emphasis on the nonlinear dynamics of the Weibel instability and beam filamentation.

  17. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1993-02-01

    The QUEGS facility at MURR has produced a number of new results and demonstrated the range of potential applications of high resolution, high intensity Moessbauer scattering. This work has been carried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and other systems, manuscripts submitted on alkali halides (Phys. Rev. B) and accurate Moessbauer lineshape measurements (Phys. Rev. C), and manuscripts in preparation on glycerol, NiAl and Moessbauer spectra obtained by modulating a scattering crystal. Recently, new collaborations have been initiated which will substantially enhance our efforts. These are with W. Steiner (Vienna), G. Coddens (Saclay), and R. D. Taylor (Los Alamos). Steiner is experienced with Fe-57 Moessbauer scattering, while Coddens specializes in quasielastic neutron scattering; both of these areas naturally complement our work. R. D. Taylor has pioneered Moessbauer spectroscopy from the time of its discovery and has already made important contributions to our study of lattice dynamics and superconductivity for lead alloyed with small quantities of tin. At the same time, a significant instrument upgrade is underway, funded in part by the DOE-URIP program.

  18. Complete recovery time after exhaustion in high-intensity work.

    PubMed

    Wu, Hsin-Chieh; Hsu, Wen-Hsin; Chen, Toly

    2005-05-15

    This study was aimed to investigate complete recovery time (CRT) after exhaustion in high-intensity work. Twenty-four subjects were divided into two groups based on the cardiorespiratory capability index, which was measured in a maximum capacity test. Each subject then performed two cycling tests (at 60% and 70% maximum working capacity). The subject continued cycling until exhaustion in each test and then sat recovering until he/she no longer felt fatigue or until the oxygen uptake (VO2) and heart rate (HR) returned to their baselines, whichever was longer. The results indicated that HR required the longest time to recover and, consequently, HR data were adopted to set the CRT. The CRT was significantly correlated with the cardiorespiratory capability index and the relative workload indices: RVO2 and RHR. The RVO2 was the average elevation in VO2 during work from the resting level as a percentage of maximum VO2 reserve. The RHR's definition was similar to that of RVO2. Based on the obtained CRT-prediction model, the CRT for a high-cardiorespiratory-capability person was 20.8, 22.1, 23.4, and 24.7 min at 50%, 60%, 70%, and 80% RHR levels, respectively. These suggested CRT values should be increased by 10 min for a low-cardiorespiratory-capability person. PMID:16087501

  19. An Investigation of High Intensity Focused Ultrasound Thrombolysis

    NASA Astrophysics Data System (ADS)

    Wright, Cameron; Hynynen, Kullervo; Goertz, David

    2011-09-01

    Investigations into high intensity focused ultrasound (HIFU) thrombolysis in vitro and in vivo in a rabbit femoral artery thrombus model were performed. A 1.51 MHz focused transducer was used to treat clots with pulse lengths of 1-10 ms, acoustic powers of 1-300 W and exposure durations of 5-20 s. Our measurements indicate the creation of acoustic radiation force induced clot displacements are insufficient to mechanically fractionate clots, despite reaching displacements >100 μm. Only under the presence of inertial cavitation was HIFU able to disrupt clots. Cavitation thresholds of 160 W in vitro and 215 W in vivo were observed. In vitro, clots insonified at powers above the cavitation threshold eroded regions up to 2.5× the transducer beam width. Successful recanalization in vivo occurred in 5/20 cases for 1ms pulses at powers >215 W. 10 ms pulses created high incidences of symptomatic bleeding while 1 ms pulses did not. These results demonstrate treatment feasibility in vivo, although further work is required to understand the influence of different acoustic parameters on treatment outcome.

  20. H- Ion Sources for High Intensity Proton Drivers

    SciTech Connect

    Dudnikov, Vadim; Johnson, Rolland P.; Stockli, Martin P; Welton, Robert F; Dudnikova, Galina

    2010-01-01

    Spallation neutron source user facilities require reliable, intense beams of protons. The technique of H- charge exchange injection into a storage ring or synchrotron can provide the needed beam currents, but may be limited by the ion sources that have currents and reliability that do not meet future requirements and emittances that are too large for efficient acceleration. In this project we are developing an H- source which will synthesize the most important developments in the field of negative ion sources to provide high current, small emittance, good lifetime, high reliability, and power efficiency. We describe planned modifications to the present external antenna source at SNS that involve: 1) replacing the present 2 MHz plasma-forming solenoid antenna with a 60 MHz saddle-type antenna and 2) replacing the permanent multicusp magnet with a weaker electromagnet, in order to increase the plasma density near the outlet aperture. The SNS test stand will then be used to verify simulations of this approach that indicate significant improvements in H- output current and efficiency, where lower RF power will allow higher duty factor, longer source lifetime, and/or better reliability.

  1. Intense Laser Ionization and Acceleration of Electrons in Highly-Charged Ions Using Vortex Laser Beams

    NASA Astrophysics Data System (ADS)

    Pi, Liang-Wen; Vikartofsky, Andrew; Starace, Anthony F.

    2016-05-01

    Recent advances in laser technology have led to the development of high-power petawatt lasers, making possible laser intensities of the order of 1022 W /cm2 . An electron in a highly-charged ion can be ionized in a laser field at its peak intensity and swiftly accelerated to GeV energies. Our prior investigation of laser acceleration of electrons using linearly-polarized Gaussian beams (with zero orbital angular momentum) has revealed that the final-state energies and ejection angles of the electrons depend on the initial target ion positions relative to the laser focus. We report here recent simulations of laser ionization and acceleration of electrons using linearly-polarized vortex laser beams (i.e., Laguerre-Gaussian beams), which carry orbital angular momentum and can spin microscopic objects. These simulations show that the inherent spiral phase structure of the vortex beams leads to improved final-state energy and ejection angle distributions of the electrons. This work is supported in part by DOE, Office of Science, Division of Chemical Sciences, Geosciences, and Biosciences, under Grant No. DE-FG02-96ER14646.

  2. Depth-specific optogenetic control in vivo with a scalable, high-density μLED neural probe.

    PubMed

    Scharf, Robert; Tsunematsu, Tomomi; McAlinden, Niall; Dawson, Martin D; Sakata, Shuzo; Mathieson, Keith

    2016-01-01

    Controlling neural circuits is a powerful approach to uncover a causal link between neural activity and behaviour. Optogenetics has been widely adopted by the neuroscience community as it offers cell-type-specific perturbation with millisecond precision. However, these studies require light delivery in complex patterns with cellular-scale resolution, while covering a large volume of tissue at depth in vivo. Here we describe a novel high-density silicon-based microscale light-emitting diode (μLED) array, consisting of up to ninety-six 25 μm-diameter μLEDs emitting at a wavelength of 450 nm with a peak irradiance of 400 mW/mm(2). A width of 100 μm, tapering to a 1 μm point, and a 40 μm thickness help minimise tissue damage during insertion. Thermal properties permit a set of optogenetic operating regimes, with ~0.5 °C average temperature increase. We demonstrate depth-dependent activation of mouse neocortical neurons in vivo, offering an inexpensive novel tool for the precise manipulation of neural activity. PMID:27334849

  3. Depth-specific optogenetic control in vivo with a scalable, high-density μLED neural probe

    PubMed Central

    Scharf, Robert; Tsunematsu, Tomomi; McAlinden, Niall; Dawson, Martin D.; Sakata, Shuzo; Mathieson, Keith

    2016-01-01

    Controlling neural circuits is a powerful approach to uncover a causal link between neural activity and behaviour. Optogenetics has been widely adopted by the neuroscience community as it offers cell-type-specific perturbation with millisecond precision. However, these studies require light delivery in complex patterns with cellular-scale resolution, while covering a large volume of tissue at depth in vivo. Here we describe a novel high-density silicon-based microscale light-emitting diode (μLED) array, consisting of up to ninety-six 25 μm-diameter μLEDs emitting at a wavelength of 450 nm with a peak irradiance of 400 mW/mm2. A width of 100 μm, tapering to a 1 μm point, and a 40 μm thickness help minimise tissue damage during insertion. Thermal properties permit a set of optogenetic operating regimes, with ~0.5 °C average temperature increase. We demonstrate depth-dependent activation of mouse neocortical neurons in vivo, offering an inexpensive novel tool for the precise manipulation of neural activity. PMID:27334849

  4. Depth-specific optogenetic control in vivo with a scalable, high-density μLED neural probe

    NASA Astrophysics Data System (ADS)

    Scharf, Robert; Tsunematsu, Tomomi; McAlinden, Niall; Dawson, Martin D.; Sakata, Shuzo; Mathieson, Keith

    2016-06-01

    Controlling neural circuits is a powerful approach to uncover a causal link between neural activity and behaviour. Optogenetics has been widely adopted by the neuroscience community as it offers cell-type-specific perturbation with millisecond precision. However, these studies require light delivery in complex patterns with cellular-scale resolution, while covering a large volume of tissue at depth in vivo. Here we describe a novel high-density silicon-based microscale light-emitting diode (μLED) array, consisting of up to ninety-six 25 μm-diameter μLEDs emitting at a wavelength of 450 nm with a peak irradiance of 400 mW/mm2. A width of 100 μm, tapering to a 1 μm point, and a 40 μm thickness help minimise tissue damage during insertion. Thermal properties permit a set of optogenetic operating regimes, with ~0.5 °C average temperature increase. We demonstrate depth-dependent activation of mouse neocortical neurons in vivo, offering an inexpensive novel tool for the precise manipulation of neural activity.

  5. Remote Sensing Tertiary Education Meets High Intensity Interval Training

    NASA Astrophysics Data System (ADS)

    Joyce, K. E.; White, B.

    2015-04-01

    Enduring a traditional lecture is the tertiary education equivalent of a long, slow, jog. There are certainly some educational benefits if the student is able to maintain concentration, but they are just as likely to get caught napping and fall off the back end of the treadmill. Alternatively, a pre-choreographed interactive workshop style class requires students to continually engage with the materials. Appropriately timed breaks or intervals allow students to recover briefly before being increasingly challenged throughout the class. Using an introductory remote sensing class at Charles Darwin University, this case study presents a transition from the traditional stand and deliver style lecture to an active student-led learning experience. The class is taught at undergraduate and postgraduate levels, with both on-campus as well as online distance learning students. Based on the concept that active engagement in learning materials promotes 'stickiness' of subject matter, the remote sensing class was re-designed to encourage an active style of learning. Critically, class content was reviewed to identify the key learning outcomes for the students. This resulted in a necessary sacrifice of topic range for depth of understanding. Graduates of the class reported high levels of enthusiasm for the materials, and the style in which the class was taught. This paper details a number of techniques that were used to engage students in active and problem based learning throughout the semester. It suggests a number of freely available tools that academics in remote sensing and related fields can readily incorporate into their teaching portfolios. Moreover, it shows how simple it can be to provide a far more enjoyable and effective learning experience for students than the one dimensional lecture.

  6. Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective

    NASA Technical Reports Server (NTRS)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

  7. Beam experiments towards high-intensity beams in RHIC

    SciTech Connect

    Montag C.; Ahrens, L.; Brennan, J.M.; Blaskiewicz, M.; Drees, A.; Fischer, W.; Hayes, T.; Huang, H.; Mernick, K.; Robert-Demolaize, G.; Smith, K.; Than, R.; Thieberger, P.; Yip, K.; Zeno, K.; Zhang, S.Y.

    2012-05-20

    Proton bunch intensities in RHIC are planned to be increased from 2 {center_dot} 10{sup 11} to 3 {center_dot} 10{sup 11} protons per bunch to increase the luminosity, together with head-on beam-beam compensation using electron lenses. To study the feasibility of the intensity increase, beam experiments are being performed. Recent experimental results are presented.

  8. A methodology for assessing high intensity RF effects in aircraft

    SciTech Connect

    Zacharias, R.A.; Avalle, C.A.; Kunz, K.S.; Molau, N.E.; Pennock, S.T.; Poggio, A.J.; Sharpe, R.M.

    1993-07-01

    Optical components have an inherent immunity to the electromagnetic interference (EMI) associated with High Intensity Radiated Fields (HIRF). The optical technology embodied in Fly-by-Light (FBL) might therefore minimize the effects of HIRF on digitally controlled systems while providing lifetime immunity to signal EMI. This is one of the primary motivations for developing FBL systems for aircraft. FBL has the potential to greatly simplify EMI certification by enabling technically acceptable laboratory tests of subsystems, as opposed to expensive full airplane tests. In this paper the authors describe a methodology for assessing EMI effects on FBL aircraft that reduces or potentially eliminates the need for full airplane tests. This methodology is based on comparing the applied EMI stress--the level of interference signal that arrives at a unit under test--versus the EMI strength of the unit--the interference level it can withstand without upset. This approach allows one to use computer models and/or low power coupling measurement and similarity (to other previously tested aircraft) to determine the stress applied to installed subsystems, and to use benchtop cable injection tests and/or mode stirred chamber radiated tests to determine the strength of the subsystem.

  9. Fast Acting Optical Forces From Far Detuned, High Intensity Light

    NASA Astrophysics Data System (ADS)

    Corder, Christopher; Arnold, Brian; Hua, Xiang; Metcalf, Harold

    2015-05-01

    We are exploring fast acting, strong optical forces from standing wave light fields with high intensity and large detuning δ >> γ , where γ is the transition linewidth. We observe these fast acting forces on a time scale of a few times the excited state lifetime τ ≡ 1 / γ thus an atom may experience at most one or two spontaneous emission events. The dipole force is typically considered when the Rabi frequency Ω << δ , but we use Ω ~ δ so the usual approximations break down because a significant excited state population can occur, even for our short interaction times that limit spontaneous emission. Our experiment measures the transverse velocity distribution of a beam of 23S He after a chosen interaction time with a perpendicular standing wave detuned from the 23S -->33P transition near 389 nm. The distribution shows velocity resonance effects that persist over a large range of Ω. We also simulate the experiment numerically using the Optical Bloch Equations and the results are consistent with our measurements. Supported by ONR and Dept. of Education GAANN

  10. High intensity ultrasound modified ovalbumin: Structure, interface and gelation properties.

    PubMed

    Xiong, Wenfei; Wang, Yuntao; Zhang, Chunlan; Wan, Jiawei; Shah, Bakht Ramin; Pei, Yaqiong; Zhou, Bin; Li, Jin; Li, Bin

    2016-07-01

    Influence of high intensity ultrasound (HIUS) on the structure and properties of ovalbumin (OVA) were investigated. It was found that the subunits and secondary structure of OVA did not change significantly with HIUS treatment from the electrophoretic patterns and circular dichroism (CD) spectrum. The amount of free sulfhydryl groups increased and intrinsic fluorescence spectra analysis indicated changes in the tertiary structure and partial unfold of OVA after sonication increased. Compared with the untreated OVA, HIUS treatment increased the emulsifying activity and foaming ability, and decreased interface tension (oil-water and air-water interface), which due to the increased surface hydrophobicity and decreased the surface net charge in OVA, while the emulsifying and foaming stability had no remarkable differences. The increased particle size may be attributed to formation of protein aggregates. Moreover, the gelation temperatures of HIUS-treated samples were higher than the untreated OVA according to the temperature sweep model rheology, and this effect was consistent with the increased in surface hydrophobicity for ultrasound treated OVA. These changes in functional properties of OVA would promote its application in food industry. PMID:26964953

  11. The WARP Code: Modeling High Intensity Ion Beams

    SciTech Connect

    Grote, D P; Friedman, A; Vay, J L; Haber, I

    2004-12-09

    The Warp code, developed for heavy-ion driven inertial fusion energy studies, is used to model high intensity ion (and electron) beams. Significant capability has been incorporated in Warp, allowing nearly all sections of an accelerator to be modeled, beginning with the source. Warp has as its core an explicit, three-dimensional, particle-in-cell model. Alongside this is a rich set of tools for describing the applied fields of the accelerator lattice, and embedded conducting surfaces (which are captured at sub-grid resolution). Also incorporated are models with reduced dimensionality: an axisymmetric model and a transverse ''slice'' model. The code takes advantage of modern programming techniques, including object orientation, parallelism, and scripting (via Python). It is at the forefront in the use of the computational technique of adaptive mesh refinement, which has been particularly successful in the area of diode and injector modeling, both steady-state and time-dependent. In the presentation, some of the major aspects of Warp will be overviewed, especially those that could be useful in modeling ECR sources. Warp has been benchmarked against both theory and experiment. Recent results will be presented showing good agreement of Warp with experimental results from the STS500 injector test stand. Additional information can be found on the web page http://hif.lbl.gov/theory/WARP{_}summary.html.

  12. S-76 high intensity radiated fields, volume 1

    NASA Astrophysics Data System (ADS)

    Blair, Jerry

    1993-10-01

    The Federal Aviation Administration (FAA) Technical Center sponsored a series of High Intensity Radiated Fields (HIRF) test on a Sikorsky S-76 rotorcraft. The project was conducted to evaluate the practicality of performing aircraft level HIRF tests, determine the effects of HIRF on a specific rotorcraft with the potential to obtain information on rotorcraft in general, and evaluate the effects of exposure to real world HIRF emitters. HIRF ground and flight tests were conducted to achieve the objective of the project. Site calibration (SCAL) measurements were made in the test area to determine the levels at which the S-76 would be irradiated when placed in the test area. Ground tests consisted of Low Level Swept Coupling (LLSC) and Low Level Swept Fields (LLSF) tests. The flight tests were flown directly into the main beam of a variety of pulsed and continuous wave (CW) transmitters including the Over the Horizon Back Scatter (OTHB), PAVE PAWS, ASR-9, FPS-65, and FPS-16 radars. Results of the S-76 tests added credibility to the existence of HIRF as a flight safety hazard. In the evaluation of the emitters, the flight tests showed repeatable instances where exposure resulted in instrumentation disruptions. It should be noted that all the observed disruptions were of a non-critical nature.

  13. S-76 high intensity radiated fields, volume 3

    NASA Astrophysics Data System (ADS)

    Blair, Jerry

    1993-10-01

    The Federal Aviation Administration (FAA) Technical Center sponsored a series of High Intensity Radiated Fields (HIRF) tests on a Sikorsky S-76 rotorcraft. The project was conducted to evaluate the practically of performing aircraft level HIRF tests, determine the effects of HIRF on a specific rotorcraft with the potential to obtain information on rotorcraft in general, and evaluate the effects of exposure to 'real world' HIRF emitters. HIRF ground and flight tests were conducted to achieve the objective of the project. Site calibration (SCAL) measurements were made in the test area to determine the levels at which the S-76 would be irradiated when placed in the test area. Ground tests consisted of Low Level Swept Coupling (LLSC) and Low Level Swept Fields (LLSF) tests. The flight tests were flown directly into the main beam of a variety of pulsed and continuous wave (CW) transmitters including the Over the Horizon Back Scatter (OTHB), PAVE PAWS, ASR-9, FPS-65, and FPS-16 radars. Results of the S-76 tests added credibility to the existence of HIRF as a flight safety hazard. In the evaluation of the emitters, the flight tests showed repeatable instances where exposure resulted in instrumentation disruptions. It should however be noted that all the observed disruptions were of a non-critical nature.

  14. S-76 high intensity radiated fields, volume 2

    NASA Astrophysics Data System (ADS)

    Blair, Jerry

    1993-10-01

    The Federal Aviation Administration (FAA) Technical Center sponsored a series of High Intensity Radiated Fields (HIRF) test on a Sikorsky S-76 rotorcraft. The project was conducted to evaluate the practically of performing aircraft level HIRF tests, determine the effects of HIRF on a specific rotorcraft with the potential to obtain information on rotorcraft in general, and evaluate the effects of exposure to real world HIRF emitters. HIRF ground and flight tests were conducted to achieve the objective of the project. Site calibration (SCAL) measurements were made in the test area to determine the levels at which the S-76 would be irradiated when placed in the test area. Ground tests consisted of Low Level Swept Coupling (LLSC) and Low Level Swept Fields (LLSF) tests. The flight tests were flown directly into the main beam of a variety of pulsed and continuous wave (CW) transmitters including the Over the Horizon Back Scatter (OTHB), PAVE PAWS, ASR-9, FPS-65, and FPS-16 radars. Results of the S-76 tests added credibility to the existence of HIRF as a flight safety hazard. In the evaluation of the emitters, the flight tests showed repeatable instances where exposure resulted in instrumentation disruptions. It should be noted that all the observed disruptions were of a non-critical nature.

  15. High intensity focused ultrasound in clinical tumor ablation

    PubMed Central

    Zhou, Yu-Feng

    2011-01-01

    Recent advances in high intensity focused ultrasound (HIFU), which was developed in the 1940s as a viable thermal tissue ablation approach, have increased its popularity. In clinics, HIFU has been applied to treat a variety of solid malignant tumors in a well-defined volume, including the pancreas, liver, prostate, breast, uterine fibroids, and soft-tissue sarcomas. In comparison to conventional tumor/cancer treatment modalities, such as open surgery, radio- and chemo-therapy, HIFU has the advantages of non-invasion, non-ionization, and fewer complications after treatment. Over 100 000 cases have been treated throughout the world with great success. The fundamental principles of HIFU ablation are coagulative thermal necrosis due to the absorption of ultrasound energy during transmission in tissue and the induced cavitation damage. This paper reviews the clinical outcomes of HIFU ablation for applicable cancers, and then summarizes the recommendations for a satisfactory HIFU treatment according to clinical experience. In addition, the current challenges in HIFU for engineers and physicians are also included. More recent horizons have broadened the application of HIFU in tumor treatment, such as HIFU-mediated drug delivery, vessel occlusion, and soft tissue erosion (“histotripsy”). In summary, HIFU is likely to play a significant role in the future oncology practice. PMID:21603311

  16. Treatment of Acne Scars With High Intensity Focused Radio Frequency.

    PubMed

    Ibrahimi, Omar A; Weiss, Robert A; Weiss, Margaret A; Halvorson, Christian R; Mayoral, Flor; Ross, E Victor; Cohen, Joel L

    2015-09-01

    In this multi-site case series, the efficacy of high intensity focused radiofrequency (RF) delivered to the dermis was evaluated for treating acne scars. A novel delivery system that uses insulated microneedles to deliver a desired thermal effect to multiple depths of the dermis while sparing the epidermis from RF injury was used. Four (4) healthy subjects from four different practices were evaluated and used in this case report. The subjects were treated between 3 or 4 times depending on the severity of the acne scars presented. The depth of thermal delivery was adjusted before each pass and all subjects received at a minimum, three passes to the treated area. Before and after photographs along with adverse effects were recorded. The theory behind the use of insulated needles with the active RF delivery at the distal tip is to allow for significant thermal injury to several layers of the dermis while avoiding thermal injury to the epidermis. This case report demonstrates significant improvement on acne scars and that all skin types should be safely treatable with minimum downtime realized. PMID:26355629

  17. Treatment of glaucoma with high intensity focused ultrasound.

    PubMed

    Aptel, Florent; Lafon, Cyril

    2015-05-01

    Glaucoma is a common disease mainly due to an increase in pressure inside the eye, leading to a progressive destruction of the optic nerve, potentially to blindness. Intraocular pressure (IOP) is the result of a balance between production of liquid that fills the eye--aqueous humour--and its resorption. All treatments for glaucoma aim to reduce IOP and can therefore have two mechanisms of action: reducing aqueous humour production by the partial destruction or medical inhibition of the ciliary body--the anatomical structure responsible for production of aqueous humour--or facilitating the evacuation of aqueous humour from the eye. Several physical methods can be used to destroy the ciliary body, e.g. laser, cryotherapy, microwave. All these methods have two major drawbacks: they are non-selective for the organ to be treated and they have an unpredictable dose–effect relationship. High intensity focused ultrasound (HIFU) can be used to coagulate the ciliary body and avoid these drawbacks. A commercially available device was marketed in the 1980s, but later abandoned, essentially for technical reasons. A smaller circular device using miniaturised transducers was recently developed and proposed for clinical practice. Experimental studies have shown selective coagulation necrosis of the treated ciliary body. The first three clinical trials in humans have shown that this device was well tolerated and allowed a significant, predictable and sustained reduction of IOP. The aim of this contribution is to present a summary of the work concerning the use of HIFU to treat glaucoma. PMID:25524084

  18. Spectroscopic imaging of metal halide high-intensity discharge lamps

    NASA Astrophysics Data System (ADS)

    Bonvallet, Geoffrey A.

    The body of this work consists of three main research projects. An optical- and near-ultraviolet-wavelength absorption study sought to determine absolute densities of ground and excited level Sc atoms, ground level Sc + ions, and ground level Na atoms in a commercial 250 W metal halide high intensity discharge lamp during operation. These measurements also allowed the determination of the arc temperature and absolute electron density as functions of radius. Through infrared emission spectroscopy, relative densities of sodium and scandium were determined as functions of radius. Using the absolute densities gained from the optical experiment, these relative densities were calibrated. In addition, direct observation of the infrared emission allowed us to characterize the infrared power losses of the lamp. When considered as a fraction of the overall power consumption, the near-infrared spectral power losses were not substantial enough to warrant thorough investigation of their reduction in these lamps. The third project was an attempt to develop a portable x-ray diagnostic experiment. Two-dimensional spatial maps of the lamps were analyzed to determine absolute elemental mercury densities and the arc temperature as a function of radius. Two methods were used to improve the calibration of the density measurements and to correct for the spread in x-ray energy: known solutions of mercury in nitric acid, and an arc lamp which was uniformly heated to evaporate the mercury content. Although many complexities arose in this experiment, its goal was successfully completed.

  19. White LED performance

    NASA Astrophysics Data System (ADS)

    Gu, Yimin; Narendran, Nadarajah; Freyssinier, Jean Paul

    2004-10-01

    Two life tests were conducted to compare the effects of drive current and ambient temperature on the degradation rate of 5 mm and high-flux white LEDs. Tests of 5 mm white LED arrays showed that junction temperature increases produced by drive current had a greater effect on the rate of light output degradation than junction temperature increases from ambient heat. A preliminary test of high-flux white LEDs showed the opposite effect, with junction temperature increases from ambient heat leading to a faster depreciation. However, a second life test is necessary to verify this finding. The dissimilarity in temperature effect among 5 mm and high-flux LEDs is likely caused by packaging differences between the two device types.

  20. AlGaN UV LED and Photodiodes Radiation Hardness and Space Qualifications and Their Applications in Space Science and High Energy Density Physics

    SciTech Connect

    Sun, K. X.

    2011-05-31

    This presentation provides an overview of robust, radiation hard AlGaN optoelectronic devices and their applications in space exploration & high energy density physics. Particularly, deep UV LED and deep UV photodiodes are discussed with regard to their applications, radiation hardness and space qualification. AC charge management of UV LED satellite payload instruments, which were to be launched in late 2012, is covered.

  1. Effects of High Intensity Focused Ultrasound on the Brain

    NASA Astrophysics Data System (ADS)

    Vykhodtseva, Natalia; McDannold, Nathan; Hynynen, Kullervo

    2007-05-01

    Bio-effects in the brain resulting from short focused ultrasound (FUS) pulses (1-10 ms, PRF=0.5, 1.0, and 2.0 Hz, frequency=1.63 MHz) at high acoustic power (up to 700W) were examined. Fifty-seven locations were targeted through a craniotomy in the brains of 11 rabbits. Temperature rise was measured with MRI-based thermometry. The animals were sacrificed 4 h or 48 h after sonications for histological evaluations. A range of effects was observed: (1) Vascular changes (vasoconstriction/occlusion). (2) Homogenization of tissue. (3) Concentric circular lesions; (4) Hemorrhagic lesions similar to what was described earlier as inertial cavitation effects. Overall, the type of damage correlated with the acoustical power, with substantial overlapping among categories. Vascular changes were found at ˜140-180W, the thresholds for homogenized tissue and hemorrhagic lesions were approximately 200W and 350W, respectively. Some of these effects might be exploited for new therapies. Vascular occlusion might also be exploited for therapy; the lesions with homogenized tissue may suggest a new mechanism for non-thermal tissue ablation; small ones for ophthalmology and for functional neurosurgery (if produced in nerve tracts). The mechanism for this effect is unknown, but with the acoustic intensities used, non-linear absorption, strong radiation forces and microbubble activity were likely to have been present. MRI-based temperature changes suggest that thermal effects were probably not responsible for these lesions, as the average focal temperature (approximately 47°C) was slightly below the threshold for thermal damage. The overlap between types of tissue effects for a given acoustic intensity indicates that a method to guide such cavitation-based therapies is needed. MRI was promising in some ways — we can detect where the effects were happening and whether or not cavitation occurred. While the artifacts in temperature mappings will make temperature measurements problematic

  2. Zernike polynomials for photometric characterization of LEDs

    NASA Astrophysics Data System (ADS)

    Velázquez, J. L.; Ferrero, A.; Pons, A.; Campos, J.; Hernanz, M. L.

    2016-02-01

    We propose a method based on Zernike polynomials to characterize photometric quantities and descriptors of light emitting diodes (LEDs) from measurements of the angular distribution of the luminous intensity, such as total luminous flux, BA, inhomogeneity, anisotropy, direction of the optical axis and Lambertianity of the source. The performance of this method was experimentally tested for 18 high-power LEDs from different manufacturers and with different photometric characteristics. A small set of Zernike coefficients can be used to calculate all the mentioned photometric quantities and descriptors. For applications not requiring a great accuracy such as those of lighting design, the angular distribution of the luminous intensity of most of the studied LEDs can be interpolated with only two Zernike polynomials.

  3. High intensity ultrasound transducer used in gene transfection

    NASA Astrophysics Data System (ADS)

    Morrison, Kyle P.; Keilman, George W.; Noble, Misty L.; Brayman, Andrew A.; Miao, Carol H.

    2012-11-01

    This paper describes a novel therapeutic high intensity non-focused ultrasound (HIU) transducer designed with uniform pressure distribution to aid in accelerated gene transfer in large animal liver tissues in vivo. The underlying HIU transducer was used to initiate homogeneous cavitation throughout the tissue while delivering up to 2.7 MPa at 1.1 MHz across its radiating surface. The HIU transducer was built into a 6 cm diameter x 1.3 cm tall housing ergonomically designed to avoid collateral damage to the surrounding anatomy during dynamic motion. The ultrasound (US) radiation was applied in a 'paintbrush-like' manner to the surface of the liver. The layers and geometry of the transducer were carefully selected to maximize the active diameter (5.74 cm), maximize the electrical to acoustic conversion efficiency (85%) to achieve 2.7 MPa of peak negative pressure, maximize the frequency operating band at the fundamental resonance to within a power transfer delta of 1 dB, and reduce the pressure delta to within 2 dB across the radiating surface. For maximum peak voltage into the transducer, a high performance piezoceramic was chosen and a DC bias circuit was built integral to the system. An apodized two element annular pattern was made from a single piezoceramic element, resulting in significant pressure uniformity enhancement. In addition to using apodization for pressure uniformity, a proprietary multi-layered structure was used to improve efficiency while sustaining an operating band from 900 kHz to 1.3 MHz. The resultant operating band allowed for dithering techniques using frequency modulation. The underlying HIU transducer for use in large animals enhances gene expression up to 6300-fold.

  4. HIGH ENERGY DENSITY PHYSICS EXPERIMENTS WITH INTENSE HEAVY ION BEAMS

    SciTech Connect

    Henestroza, E.; Leitner, M.; Logan, B.G.; More, R.M.; Roy, P.K.; Ni, P.; Seidl, P.A.; Waldron, W.L.; Barnard, J.J.

    2010-03-16

    The US heavy ion fusion science program has developed techniques for heating ion-beam-driven warm dense matter (WDM) targets. The WDM conditions are to be achieved by combined longitudinal and transverse space-charge neutralized drift compression of the ion beam to provide a hot spot on the target with a beam spot size of about 1 mm, and pulse length about 1-2 ns. As a technique for heating volumetric samples of matter to high energy density, intense beams of heavy ions are capable of delivering precise and uniform beam energy deposition dE/dx, in a relatively large sample size, and the ability to heat any solid-phase target material. Initial experiments use a 0.3 MeV K+ beam (below the Bragg peak) from the NDCX-I accelerator. Future plans include target experiments using the NDCX-II accelerator, which is designed to heat targets at the Bragg peak using a 3-6 MeV lithium ion beam. The range of the beams in solid matter targets is about 1 micron, which can be lengthened by using porous targets at reduced density. We have completed the fabrication of a new experimental target chamber facility for WDM experiments, and implemented initial target diagnostics to be used for the first target experiments in NDCX-1. The target chamber has been installed on the NDCX-I beamline. The target diagnostics include a fast multi-channel optical pyrometer, optical streak camera, VISAR, and high-speed gated cameras. Initial WDM experiments will heat targets by compressed NDCX-I beams and will explore measurement of temperature and other target parameters. Experiments are planned in areas such as dense electronegative targets, porous target homogenization and two-phase equation of state.

  5. HIGH ENERGY DENSITY PHYSICS EXPERIMENTS WITH INTENSE HEAVY ION BEAMS

    SciTech Connect

    Bieniosek, F.M.; Henestroza, E.; Leitner, M.; Logan, B.G.; More, R.M.; Roy, P.K.; Ni, P.; Seidl, P.A.; Waldron, W.L.; Barnard, J.J.

    2008-08-01

    The US heavy ion fusion science program has developed techniques for heating ion-beam-driven warm dense matter (WDM) targets. The WDM conditions are to be achieved by combined longitudinal and transverse space-charge neutralized drift compression of the ion beam to provide a hot spot on the target with a beam spot size of about 1 mm, and pulse length about 1-2 ns. As a technique for heating volumetric samples of matter to high energy density, intense beams of heavy ions are capable of delivering precise and uniform beam energy deposition dE/dx, in a relatively large sample size, and the ability to heat any solid-phase target material. Initial experiments use a 0.3 MeV K+ beam (below the Bragg peak) from the NDCX-I accelerator. Future plans include target experiments using the NDCX-II accelerator, which is designed to heat targets at the Bragg peak using a 3-6 MeV lithium ion beam. The range of the beams in solid matter targets is about 1 micron, which can be lengthened by using porous targets at reduced density. We have completed the fabrication of a new experimental target chamber facility for WDM experiments, and implemented initial target diagnostics to be used for the first target experiments in NDCX-1. The target chamber has been installed on the NDCX-I beamline. The target diagnostics include a fast multi-channel optical pyrometer, optical streak camera, VISAR, and high-speed gated cameras. Initial WDM experiments will heat targets by compressed NDCX-I beams and will explore measurement of temperature and other target parameters. Experiments are planned in areas such as dense electronegative targets, porous target homogenization and two-phase equation of state.

  6. Tools and techniques for estimating high intensity RF effects

    SciTech Connect

    Zacharias, R.; Pennock, S.; Poggio, A.; Ray, S.

    1991-07-01

    With the ever-increasing dependence of modern aircraft on sophisticated avionics and electronic controls, the need to assure aircraft survivatality when exposed to high Intensity RF (HIRF) signals has become of great Interest. Advisory regulation is currently being proposed which would require testing and/or analysis to assure RF hardness of installed flight critical and flight essential equipment. While full-aircraft, full-threat testing may be the most thorough manner to assure survivability, it is not generally practical in loins of cost. Various combinations of limited full-aircraft testing, box-level testing, modeling, and analysis are also being considered as methods to achieve compliance. Modeling, analysis, and low power measurements may hold the key to making full-system survivability estimates at reasonable cost. In this paper we will describe some of the tools and techniques we use for estimating and measuring coupling and component disturbance. A finite difference time domain modeling code, TSAR, used to predict coupling will be described. This code has the capability to quickly generate a mesh model to represent the test object. Some recent applications as well as the advantages and limitations of using such a code will be described. We will also describe some of the facilities and techniques we have developed for making low power coupling measurements and for making direct injection test measurements of device disturbance. Some scaling laws for coupling and device effects will be presented. A method to extrapolate these low-power test results to high-power full-system effects will be presented.

  7. Rain simulation studies for high-intensity acoustic nose cavities

    NASA Astrophysics Data System (ADS)

    Clayton, R. M.; Cho, Y. I.; Shakkottai, P.; Back, L. H.

    1988-03-01

    Unarmed plastic projectiles can be equipped with small axisymmetric cavities for the generation of intense tones that are useful in training maneuvers. Attention is presently given to the simulation of rainfall in an airstream and the effect of rain droplet impingement on the nose of projectiles, and especially to any penetration or accumulation of water at the base of the cavity that might increase the fundamental cavity frequency and/or reduce the intensity of sound production during rain conditions.

  8. Performance of a constructed wetland treating intensive shrimp aquaculture wastewater under high hydraulic loading rate.

    PubMed

    Lin, Ying-Feng; Jing, Shuh-Ren; Lee, Der-Yuan; Chang, Yih-Feng; Chen, Yi-Ming; Shih, Kai-Chung

    2005-04-01

    A water treatment unit, mainly consisting of free water surface (FWS) and subsurface flow (SF) constructed wetland cells, was integrated into a commercial-scale recirculating aquaculture system for intensive shrimp culture. This study investigated performance of the treatment wetlands for controlling water quality. The results showed that the FWS-SF cells effectively removed total suspended solids (55-66%), 5-day biochemical oxygen demand (37-54%), total ammonia (64-66%) and nitrite (83-94%) from the recirculating water under high hydraulic loading rates (1.57-1.95 m/day). This led to a water quality that was suitable for shrimp culture and effluent that always satisfied the discharge standards. The area ratios of wetlands to culture tank being demonstrated (0.43) and calculated (0.096) in this study were both significantly lower than the reported values. Accordingly, a constructed wetland was technically and economically feasible for managing water quality of an intensive aquaculture system. PMID:15620586

  9. Method of making a high intensity solar cell

    SciTech Connect

    Sater, B. L.

    1985-05-14

    A method of manufacturing a high intensity edge illuminated solar cell is provided which comprises the following steps. A semiconductor substrate is formed having first, second and third essentially parallel layers having impurity doped semiconductor material and arranged in that order with the first and third layers terminating in opposing essentially parallel first and second major surfaces. The second layer is of a first type conductivity and the first layer is an opposite second type conductivity so as to define a PN junction between the first and second layers and which junction is essentially parallel to the first and second major surfaces. The third layer is of the first type conductivity but is of greater impurity concentration than that of the second layer for providing a built-in electrostatic drift field to enhance minority carrier movement toward the PN junction. The junction of the second and third layers is essentially parallel to the PN junction. First and second ohmic contact layers are applied on the first and second major surfaces respectively so as to provide electrical contacts thereon. The substrate is separated along separating planes into segments. These separating planes provide major working surfaces extending between the first and second major surfaces. The major working surfaces each contain a plurality of edge surfaces of the first, second and third impurity doped semiconductor material. The major working surfaces of each segment are prepared by passivating the edge surfaces of the first, second and third impurity doped material. At least one of the major working surfaces serves to receive incident radiation and thereby it serves as an operating surface. An accumulation layer is incorporated at the operating surface containing the first type conductivity semiconductor material to provide thereat a drift field to minimize minority carrier recombination at the operating surface.

  10. Development of a High Intensity Focused Ultrasound (HIFU) Hydrophone System

    NASA Astrophysics Data System (ADS)

    Schafer, Mark E.; Gessert, James

    2009-04-01

    The growing clinical use of High Intensity Focused Ultrasound (HIFU) has driven a need for reliable, reproducible measurements of HIFU acoustic fields. We have previously presented data on a reflective scatterer approach, incorporating several novel features for improved bandwidth, reliability, and reproducibility [Proc. 2005 IEEE Ultrasonics Symposium, 1739-1742]. We now report on several design improvements which have increase the signal to noise ratio of the system, and potentially reduced the cost of implementation. For the scattering element, we now use an artificial sapphire material to provide a more uniform radiating surface. The receiver is a segmented, truncated spherical structure with a 10 cm radius; the scattering element is positioned at the center of the sphere. The receiver is made from 25 micron thick, biaxially stretched PVDF, with a Pt-Au electrode on the front surface. In the new design, a specialized backing material provides the stiffness required to maintain structural stability, while at the same time providing both electrical shielding and ultrasonic absorption. Compared with the previous version, the new receiver design has improved the noise performance by 8-12 dB; the new scattering sphere has reduced the scattering loss by another 14 dB, producing an effective sensitivity of -298 dB re 1 microVolt/Pa. The design trade-off still involves receiver sensitivity with effective spot size, and signal distortion from the scatter structure. However, the reduced cost and improved repeatability of the new scatter approach makes the overall design more robust for routine waveform measurements of HIFU systems.

  11. Glass Strengthening via High-Intensity Plasma-Arc Heating

    SciTech Connect

    Wereszczak, Andrew A; Harper, David C; Duty, Chad E; Patel, P

    2010-01-01

    The use of a high-intensity plasma-arc lamp was used to irradiate the surface of soda-lime silicate glass tiles to determine if an increase in strength could be achieved. The lamp had a power density of 3500 W/cm2, a processing area of 1 cm x 10 cm, irradiated near-infrared heating at a wavelength between 0.2 1.4 m, and was controlled to unidirectionally sweep across 50-mm-square tiles at a constant speed of 8 mm/s. Ring-on-ring (RoR) equibiaxial flexure and 4 pt uni-directional flexure testings of entire tiles were used to measure and compare failure stress distributions of treated and untreated glass. Even with non-optimized processing conditions, RoR failure stress increased by approximately 25% and the 4 pt bend failure stress increased by approximately 65%. Strengthening was due to a fire-polishing-like mechanism. The arc-lamp heat-treatment caused the location of the strength-limiting flaws in the 4-pt-bend tiles to change; namely, failure initiation occurred on the gage section surface for the treated glass whereas it occurred at a gage section edge for the untreated. Arc-lamp heat-treatment is attractive not only because it provides strengthening, but because it can (non-contact) process large amounts of glass quickly and inexpensively, and is a process that either a glass manufacturer or end-user can readily employ.

  12. Development of a High Intensity Focused Ultrasound (HIFU) Hydrophone System

    SciTech Connect

    Schafer, Mark E.; Gessert, James

    2009-04-14

    The growing clinical use of High Intensity Focused Ultrasound (HIFU) has driven a need for reliable, reproducible measurements of HIFU acoustic fields. We have previously presented data on a reflective scatterer approach, incorporating several novel features for improved bandwidth, reliability, and reproducibility [Proc. 2005 IEEE Ultrasonics Symposium, 1739-1742]. We now report on several design improvements which have increase the signal to noise ratio of the system, and potentially reduced the cost of implementation. For the scattering element, we now use an artificial sapphire material to provide a more uniform radiating surface. The receiver is a segmented, truncated spherical structure with a 10 cm radius; the scattering element is positioned at the center of the sphere. The receiver is made from 25 micron thick, biaxially stretched PVDF, with a Pt-Au electrode on the front surface. In the new design, a specialized backing material provides the stiffness required to maintain structural stability, while at the same time providing both electrical shielding and ultrasonic absorption. Compared with the previous version, the new receiver design has improved the noise performance by 8-12 dB; the new scattering sphere has reduced the scattering loss by another 14 dB, producing an effective sensitivity of -298 dB re 1 microVolt/Pa. The design trade-off still involves receiver sensitivity with effective spot size, and signal distortion from the scatter structure. However, the reduced cost and improved repeatability of the new scatter approach makes the overall design more robust for routine waveform measurements of HIFU systems.

  13. High Intensity Focused Ultrasound induced Gene Activation in Solid Tumors

    NASA Astrophysics Data System (ADS)

    Liu, Yunbo; Kon, Takashi; Li, Chuanyuan; Zhong, Pei

    2006-05-01

    In this work, the feasibility of using high intensity focused ultrasound (HIFU) to activate trans-gene expression in a mouse tumor model was investigated. 4T1 cancer cells were implanted subcutaneously in the hind limbs of Balb/C mice and adenovirus luciferase gene vectors under the control of heat shock protein 70B promoter (Adeno-hsp70B-Luc) were injected intratumoraly for gene transfection. One day following the virus injection, the transfected tumors were heated to a peak temperature of 55, 65, 75, and 85°C, respectively, in 10s at multiple sites around the center of the tumor using a HIFU transducer operated at either 1.1-MHz (fundamental) or 3.3-MHz (3rd harmonic) frequency. Inducible luciferase gene expression was found to vary from 15-fold to 120-fold of the control group following 1.1-MHz HIFU exposure. The maximum gene activation was produced at a peak temperature of 65˜75°C one day following HIFU exposure and decayed gradually to baseline level within 7 days. The inducible gene activation produced by 3.3-MHz HIFU exposure (75°C-10s) was found to be comparable to that produced by hyperthermia (42°C-30min). Altogether, these results demonstrate the feasibility of using HIFU as a simple and versatile physical means to regulate trans-gene expression in vivo. This unique feature may be explored in the future for a synergistic combination of HIFU-induced thermal ablation with heat-induced gene therapy for improved cancer therapy.

  14. HIGH-SPEED BICHROMATIC INSPECTION OF WHEAT KERNELS FOR MOLD AND COLOR CLASS USING HIGH-POWER PULSED LEDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High-speed optical sorting of seeds in commercial processing is routinely practiced for removal of discolored seeds, seeds from volunteer plants, and non-seed objects. Sorters are conventionally based on monochromatic or bichromatic light from broad wavebands in the visible and near-infrared region...

  15. High-Intensity Training and Salivary Immunoglobulin A Responses in Professional Top-Level Soccer Players: Effect of Training Intensity.

    PubMed

    Owen, Adam L; Wong, Del P; Dunlop, Gordon; Groussard, Carole; Kebsi, Wiem; Dellal, Alexandre; Morgans, Ryland; Zouhal, Hassane

    2016-09-01

    Owen, AL, Wong, DP, Dunlop, G, Groussard, C, Kebsi, W, Dellal, A, Morgans, R, and Zouhal, H. High-intensity training and salivary immunoglobulin A responses in professional top-level soccer players: Effect of training intensity. J Strength Cond Res 30(9): 2460-2469, 2016-This study aimed (a) to test the hypothesis that salivary immunoglobulin A (s-IgA) would vary with training intensity sessions (low-intensity [LI] vs. high-intensity sessions [HI]) during a traditional training program divided into 4 training periods and (b) to identify key variables (e.g., GPS data, rating of perceived exertion [RPE], and training duration), which could affect s-IgA. Saliva samples of 10 elite professional soccer players were collected (a) before the investigation started to establish the baseline level and (b) before and after each 4 training sessions (LI vs. HI). Training intensity was monitored as internal (through heart rate responses and RPE) and external (through GPS) loads. High-intensity sessions were associated with higher external load (GPS) and with higher RPE. Baseline and pretraining s-IgA did not differ between the 4 training sessions both for HI and LI. Post-training s-IgA were not different (in absolute value and in percentage of change) between HI and LI sessions at the first 3 periods. However, at the fourth period, s-IgA concentration for HI session was significantly lower (p ≤ 0.05) than the LI session. The percentage change between s-IgA post-training and s-IgA baseline concentrations differ significantly (p ≤ 0.05) between HI and LI training sessions. Significant correlations between s-IgA and training intensity were also noted. High-intensity soccer training sessions might cause a significant decrease in s-IgA values during the postexercise window as compared with LI sessions. This study encourages coaches to monitor s-IgA in routine, particularly during HI training periods, to take precautions to avoid upper respiratory tract infection in highly trained

  16. High efficiency quantum dot and organic LEDs with a back-cavity and a high index substrate

    NASA Astrophysics Data System (ADS)

    Liang, Haowen; Luo, Zhenyue; Zhu, Ruidong; Dong, Yajie; Lee, Jiun-Haw; Zhou, Jianying; Wu, Shin-Tson

    2016-04-01

    We report a back-cavity design to enhance the optical efficiency of a quantum dot light-emitting diode (QLED) or an organic light-emitting diode (OLED) for display and lighting applications. Our simulation results show that the back-cavity design exhibits two major advantages: (1) the transparent electrode helps to increase the transmittance of backward light despite using a semi-transparent metal electrode, and (2) the thickness of the low index optical buffer layer can be optimized to modify the proportion of each optical channel. The proposed back-cavity also helps to lower the refractive index of the high-index substrate from ~2.0 to ~1.8 for achieving high optical efficiency. Finally, the introduced back-cavity does not degrade the color performance of the QLED/OLED.

  17. 21 CFR 1040.30 - High-intensity mercury vapor discharge lamps.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false High-intensity mercury vapor discharge lamps. 1040...-intensity mercury vapor discharge lamps. (a) Applicability. The provisions of this section apply to any high-intensity mercury vapor discharge lamp that is designed, intended, or promoted for illumination purposes...

  18. 21 CFR 1040.30 - High-intensity mercury vapor discharge lamps.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false High-intensity mercury vapor discharge lamps. 1040...-intensity mercury vapor discharge lamps. (a) Applicability. The provisions of this section apply to any high-intensity mercury vapor discharge lamp that is designed, intended, or promoted for illumination purposes...

  19. 21 CFR 1040.30 - High-intensity mercury vapor discharge lamps.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false High-intensity mercury vapor discharge lamps. 1040...-intensity mercury vapor discharge lamps. (a) Applicability. The provisions of this section apply to any high-intensity mercury vapor discharge lamp that is designed, intended, or promoted for illumination purposes...

  20. Scaling to Ultra-High Intensities by High-Energy Petawatt Beam Combining

    SciTech Connect

    Siders, C W; Jovanovic, I; Crane, J; Rushford, M; Lucianetti, A; Barty, C J

    2006-06-23

    The output pulse energy from a single-aperture high-energy laser amplifier (e.g. fusion lasers such as NIF and LMJ) are critically limited by a number of factors including optical damage, which places an upper bound on the operating fluence; parasitic gain, which limits together with manufacturing costs the maximum aperture size to {approx} 40-cm; and non-linear phase effects which limits the peak intensity. For 20-ns narrow band pulses down to transform-limited sub-picosecond pulses, these limiters combine to yield 10-kJ to 1-kJ maximum pulse energies with up to petawatt peak power. For example, the Advanced Radiographic Capability (ARC) project at NIF is designed to provide kilo-Joule pulses from 0.75-ps to 50-ps, with peak focused intensity above 10{sup 19} W/cm{sup 2}. Using such a high-energy petawatt (HEPW) beamline as a modular unit, they discuss large-scale architectures for coherently combining multiple HEPW pulses from independent apertures, called CAPE (Coherent Addition of Pulses for Energy), to significantly increase the peak achievable focused intensity. Importantly, the maximum intensity achievable with CAPE increases non-linearly. Clearly, the total integrated energy grows linearly with the number of apertures N used. However, as CAPE combines beams in the focal plane by increasing the angular convergence to focus (i.e. the f-number decreases), the foal spot diameter scales inversely with N. Hence the peak intensity scales as N{sup 2}. Using design estimates for the focal spot size and output pulse energy (limited by damage fluence on the final compressor gratings) versus compressed pulse duration in the ARC system, Figure 2 shows the scaled focal spot intensity and total energy for various CAPE configurations from 1,2,4, ..., up to 192 total beams. They see from the fixture that the peak intensity for event modest 8 to 16 beam combinations reaches the 10{sup 21} to 10{sup 22} W/cm{sup 2} regime. With greater number of apertures, or with

  1. Large area LED package

    NASA Astrophysics Data System (ADS)

    Goullon, L.; Jordan, R.; Braun, T.; Bauer, J.; Becker, F.; Hutter, M.; Schneider-Ramelow, M.; Lang, K.-D.

    2015-03-01

    Solid state lighting using LED-dies is a rapidly growing market. LED-dies with the needed increasing luminous flux per chip area produce a lot of heat. Therefore an appropriate thermal management is required for general lighting with LEDdies. One way to avoid overheating and shorter lifetime is the use of many small LED-dies on a large area heat sink (down to 70 μm edge length), so that heat can spread into a large area while at the same time light also appears on a larger area. The handling with such small LED-dies is very difficult because they are too small to be picked with common equipment. Therefore a new concept called collective transfer bonding using a temporary carrier chip was developed. A further benefit of this new technology is the high precision assembly as well as the plane parallel assembly of the LED-dies which is necessary for wire bonding. It has been shown that hundred functional LED-dies were transferred and soldered at the same time. After the assembly a cost effective established PCB-technology was applied to produce a large-area light source consisting of many small LED-dies and electrically connected on a PCB-substrate. The top contacts of the LED-dies were realized by laminating an adhesive copper sheet followed by LDI structuring as known from PCB-via-technology. This assembly can be completed by adding converting and light forming optical elements. In summary two technologies based on standard SMD and PCB technology have been developed for panel level LED packaging up to 610x 457 mm2 area size.

  2. Effectiveness of a nurse-led intensive home-visitation programme for first-time teenage mothers (Building Blocks): a pragmatic randomised controlled trial

    PubMed Central

    Robling, Michael; Bekkers, Marie-Jet; Bell, Kerry; Butler, Christopher C; Cannings-John, Rebecca; Channon, Sue; Martin, Belen Corbacho; Gregory, John W; Hood, Kerry; Kemp, Alison; Kenkre, Joyce; Montgomery, Alan A; Moody, Gwenllian; Owen-Jones, Eleri; Pickett, Kate; Richardson, Gerry; Roberts, Zoë E S; Ronaldson, Sarah; Sanders, Julia; Stamuli, Eugena; Torgerson, David

    2016-01-01

    Summary Background Many countries now offer support to teenage mothers to help them to achieve long-term socioeconomic stability and to give a successful start to their children. The Family Nurse Partnership (FNP) is a licensed intensive home-visiting intervention developed in the USA and introduced into practice in England that involves up to 64 structured home visits from early pregnancy until the child's second birthday by specially recruited and trained family nurses. We aimed to assess the effectiveness of giving the programme to teenage first-time mothers on infant and maternal outcomes up to 24 months after birth. Methods We did a pragmatic, non-blinded, randomised controlled, parallel-group trial in community midwifery settings at 18 partnerships between local authorities and primary and secondary care organisations in England. Eligible participants were nulliparous and aged 19 years or younger, and were recruited at less than 25 weeks' gestation. Field-based researchers randomly allocated mothers (1:1) via remote randomisation (telephone and web) to FNP plus usual care (publicly funded health and social care) or to usual care alone. Allocation was stratified by site and minimised by gestation (<16 weeks vs ≥16 weeks), smoking status (yes vs no), and preferred language of data collection (English vs non-English). Mothers and assessors (local researchers at baseline and 24 months' follow-up) were not masked to group allocation, but telephone interviewers were blinded. Primary endpoints were biomarker-calibrated self-reported tobacco use by the mother at late pregnancy, birthweight of the baby, the proportion of women with a second pregnancy within 24 months post-partum, and emergency attendances and hospital admissions for the child within 24 months post-partum. Analyses were by intention to treat. This trial is registered with ISRCTN, number ISRCTN23019866. Findings Between June 16, 2009, and July 28, 2010, we screened 3251 women. After enrolment, 823

  3. Experimental and numerical study of high intensity argon cluster beams

    SciTech Connect

    Korobeishchikov, N. G.; Kalyada, V. V.; Shmakov, A. A.; Zarvin, A. E.; Skovorodko, P. A.

    2014-12-09

    Experimental and numerical investigations of expansion of argon with homogeneous condensation in supersonic conical nozzle and in free jet behind it were carried out. Optimal parameters (stagnation pressure, nozzle-skimmer distance) for the formation of cluster beam with maximum intensity were determined. Two available models for nonequilibrium nucleation were tested. The numerical results are in satisfactory agreement with the measured data.

  4. Experimental Research at the Intensity Frontier in High Energy Physics

    SciTech Connect

    Marshak, Marvin L.

    2014-06-30

    This Final Report describes DOE-supported Intensity Frontier research by the University of Minnesota during the interval April 1, 2011 to March 31, 2014. Primary activities included the MINOS, NOvA and LBNE Experiments and Heavy Quark studies at BES III.

  5. Ultrashort pulse high intensity laser illumination of a simple metal

    NASA Astrophysics Data System (ADS)

    Milchberg, H. M.; Freeman, R. R.; Davey, S. C.

    1988-10-01

    We have observed the self-reflection of intense, sub-picosecond 308 nm light pulse incident on a planar Al target and have inferred the electrical conductivity of solid density Al. The pulse lengths were sufficiently short that no significant expansion of the target occurred during the measurement.

  6. Investigation of the Frohlich hypothesis with high intensity terahertz radiation

    NASA Astrophysics Data System (ADS)

    Weightman, Peter

    2014-03-01

    This article provides an update to recent reviews of the Frohlich hypothesis that biological organisation is facilitated by the creation of coherent excited states driven by a flow of free energy provided by metabolic processes and mediated by molecular motions in the terahertz range. Sources of intense terahertz radiation have the potential to test this hypothesis since if it is true the growth and development of sensitive systems such as stem cells should be influenced by irradiation with intense terahertz radiation. A brief survey of recent work shows that it is not yet possible to make an assessment of the validity of the Frohlich hypothesis. Under some conditions a variety of cell types respond to irradiation with intense THz radiation in ways that involve changes in the activity of their DNA. In other experiments very intense and prolonged THz radiation has no measureable effect on the behavior of very sensitive systems such as stem cells. The wide variation in experimental conditions makes it impossible to draw any conclusions as to characteristics of THz radiation that will induce a response in living cells. It is possible that in environments suitable for their maintenance and growth cells are capable of compensating for any effects caused by exposure to THz radiation up to some currently unknown level of THz peak power.

  7. LED luminaire with controlled light distribution

    NASA Astrophysics Data System (ADS)

    Schertler, Donald J.; Sales, Tasso R. M.; Chakmakjian, Stephen; Morris, G. Michael

    2006-08-01

    Unless coupled with some collimating optics, LED sources generally scatter with wide-angle Lambertian intensity profiles. The luminous output of such sources is not amenable to control and redistribution in an efficient manner. In this work we present the design and manufacturing of structures that are able to collect virtually all light from Lambertian LED sources and direct it towards diffusers engineered to illuminate specific regions of space in a controlled fashion. The resulting "engineered luminaire" is thus capable of highly efficient light control and can be applied to a wide variety of illumination situations such as general and architectural lighting.

  8. Max Tech and Beyond: High-Intensity Discharge Lamps

    SciTech Connect

    Scholand, Michael

    2012-04-01

    High-intensity discharge (HID) lamps are most often found in industrial and commercial applications, and are the light source of choice in street and area lighting, and sports stadium illumination. HID lamps are produced in three types - mercury vapor (MV), high pressure sodium (HPS) and metal halide (MH). Of these, MV and MH are considered white-light sources (although the MV exhibits poor color rendering) and HPS produces a yellow-orange color light. A fourth lamp, low-pressure sodium (LPS), is not a HID lamp by definition, but it is used in similar applications and thus is often grouped with HID lamps. With the notable exception of MV which is comparatively inefficient and in decline in the US from both a sales and installed stock point of view; HPS, LPS and MH all have efficacies over 100 lumens per watt. The figure below presents the efficacy trends over time for commercially available HID lamps and LPS, starting with MV and LPS in 1930's followed by the development of HPS and MH in the 1960's. In HID lamps, light is generated by creating an electric arc between two electrodes in an arc tube. The particles in the arc are partially ionized, making them electrically conductive, and a light-emitting 'plasma' is created. This arc occurs within the arc tube, which for most HID lamps is enclosed within an evacuated outer bulb that thermally isolates and protects the hot arc tube from the surroundings. Unlike a fluorescent lamp that produces visible light through down-converting UV light with phosphors, the arc itself is the light source in an HID lamp, emitting visible radiation that is characteristic of the elements present in the plasma. Thus, the mixture of elements included in the arc tube is one critical factor determining the quality of the light emitted from the lamp, including its correlated color temperature (CCT) and color rendering index (CRI). Similar to fluorescent lamps, HID lamps require a ballast to start and maintain stable operating conditions, and

  9. Neurological applications of transcranial high intensity focused ultrasound.

    PubMed

    Wang, Tony R; Dallapiazza, Rob; Elias, W Jeff

    2015-05-01

    Advances in transcranial MRI-guided focused ultrasound have renewed interest in lesioning procedures in functional neurosurgery with a potential role in the treatment of neurological conditions such as chronic pain, brain tumours, movement disorders and psychiatric diseases. While the use of transcranial MRI-guided focused ultrasound represents a new innovation in neurosurgery, ultrasound has been used in neurosurgery for almost 60 years. This paper reviews the major historical milestones that have led to modern transcranial focused ultrasound and discusses current and evolving applications of ultrasound in the brain. PMID:25703389

  10. Ammonium hydroxide modulated synthesis of high-quality fluorescent carbon dots for white LEDs with excellent color rendering properties.

    PubMed

    Wang, Shengda; Zhu, Zhifeng; Chang, Yajing; Wang, Hui; Yuan, Nan; Li, Guopeng; Yu, Dabin; Jiang, Yang

    2016-07-22

    A novel type of aqueous fluorescent carbon dot (CD) was synthesized using citric acid as the only carbon source via an ammonium hydroxide modulated method, providing a blue color gamut. The amino group is considered to be the key factor in the high fluorescence of CDs and a model is established to investigate the mechanism of fluorescence. In addition, white light-emitting diodes (WLEDs) are fabricated by utilizing the prepared CDs and rare earth luminescent materials (SrSi2O2N2:Eu and Sr2Si5N8:Eu) as color conversion layers and UV-LED chips as the excitation light source. The WLEDs produce bright white light with attractive color rendering properties including a color rendering index of up to 95.1, a CIE coordinate of (0.33, 0.37), and a T c of 5447 K under a 100 mA driven current, indicating that the CDs are promising in the field of optoelectronic devices. PMID:27276359

  11. Ammonium hydroxide modulated synthesis of high-quality fluorescent carbon dots for white LEDs with excellent color rendering properties

    NASA Astrophysics Data System (ADS)

    Wang, Shengda; Zhu, Zhifeng; Chang, Yajing; Wang, Hui; Yuan, Nan; Li, Guopeng; Yu, Dabin; Jiang, Yang

    2016-07-01

    A novel type of aqueous fluorescent carbon dot (CD) was synthesized using citric acid as the only carbon source via an ammonium hydroxide modulated method, providing a blue color gamut. The amino group is considered to be the key factor in the high fluorescence of CDs and a model is established to investigate the mechanism of fluorescence. In addition, white light-emitting diodes (WLEDs) are fabricated by utilizing the prepared CDs and rare earth luminescent materials (SrSi2O2N2:Eu and Sr2Si5N8:Eu) as color conversion layers and UV-LED chips as the excitation light source. The WLEDs produce bright white light with attractive color rendering properties including a color rendering index of up to 95.1, a CIE coordinate of (0.33, 0.37), and a T c of 5447 K under a 100 mA driven current, indicating that the CDs are promising in the field of optoelectronic devices.

  12. Intensive land use in the Swedish mountains between AD 800 and 1200 led to deforestation and ecosystem transformation with long-lasting effects.

    PubMed

    Östlund, Lars; Hörnberg, Greger; DeLuca, Thomas H; Liedgren, Lars; Wikström, Peder; Zackrisson, Olle; Josefsson, Torbjörn

    2015-10-01

    Anthropogenic deforestation has shaped ecosystems worldwide. In subarctic ecosystems, primarily inhabited by native peoples, deforestation is generally considered to be mainly associated with the industrial period. Here we examined mechanisms underlying deforestation a thousand years ago in a high-mountain valley with settlement artifacts located in subarctic Scandinavia. Using the Heureka Forestry Decision Support System, we modeled pre-settlement conditions and effects of tree cutting on forest cover. To examine lack of regeneration and present nutrient status, we analyzed soil nitrogen. We found that tree cutting could have deforested the valley within some hundred years. Overexploitation left the soil depleted beyond the capacity of re-establishment of trees. We suggest that pre-historical deforestation has occurred also in subarctic ecosystems and that ecosystem boundaries were especially vulnerable to this process. This study improves our understanding of mechanisms behind human-induced ecosystem transformations and tree-line changes, and of the concept of wilderness in the Scandinavian mountain range. PMID:25678026

  13. Volumetric intensity dependence on the formation of molecular and atomic ions within a high intensity laser focus.

    PubMed

    Robson, Lynne; Ledingham, Kenneth W D; McKenna, Paul; McCanny, Thomas; Shimizu, Seiji; Yang, Jiamin M; Wahlström, Claes-Göran; Lopez-Martens, Rodrigo; Varju, Katalin; Johnsson, Per; Mauritsson, Johan

    2005-01-01

    The mechanism of atomic and molecular ionization in intense, ultra-short laser fields is a subject which continues to receive considerable attention. An inherent difficulty with techniques involving the tight focus of a laser beam is the continuous distribution of intensities contained within the focus, which can vary over several orders of magnitude. The present study adopts time of flight mass spectrometry coupled with a high intensity (8 x 10(15) Wcm(-2)), ultra-short (20 fs) pulse laser in order to investigate the ionization and dissociation of the aromatic molecule benzene-d1 (C(6)H(5)D) as a function of intensity within a focused laser beam, by scanning the laser focus in the direction of propagation, while detecting ions produced only in a "thin" slice (400 and 800 microm) of the focus. The resultant TOF mass spectra varies significantly, highlighting the dependence on the range of specific intensities accessed and their volumetric weightings on the ionization/dissociation pathways accessed. PMID:15653366

  14. The TEA CO2-Lasers with High Output Emission Intensity

    NASA Astrophysics Data System (ADS)

    Panchenko, Yu. N.; Losev, V. F.; Puchikin, А. V.; Jun, Yao

    2014-03-01

    TEA CO2-lasers generating short pulse radiation and operating in a pulse-periodic mode with the repetition rate up to 10 Hz have been developed. It is shown that the addition of nitrogen up to 8% in the mixture of molecular gases СО2:H2 = 500:50 at a total pressure of P = 0.6 bar enhances the peak emission power maintaining the temporary pulse shape. An output beam intensity of 12.3 MW/cm2 was obtained for the 30 ns pulse at a laser efficiency of 2.8%. In a compact TEA СО2-laser with an active medium volume of 6 cm3, a beam with an output intensity of 24 MW/cm2 at pulse duration of 70 ns was obtained.

  15. Extreme light. An intense pursuit of fundamental high energy physics

    NASA Astrophysics Data System (ADS)

    Mourou, Gérard; Wheeler, Jonathan A.; Tajima, Toshiki

    2015-09-01

    By the compression of petawatt pulses to multi-exawatt, a new route for the generation of Schwinger intensities capable of producing highenergy radiation and particle beams with extremely short time structure down to the attosecond-zeptosecond regime is being presented. Far from the traditional laser investigation in the eV regime, this laser-based approach offers a new paradigm to investigate the structure of vacuum and applications to subatomic physics.

  16. Laser Injection Optics for High-Intensity Transmission in Multimode Fibers

    SciTech Connect

    SETCHELL,ROBERT E.

    2000-08-29

    An increasing number of applications are requiring fiber transmission of high-intensity laser pulses. The authors particular interests have led them to examine carefully the fiber transmission of Q-switched pulses from multimode Nd:YAG lasers at their fundamental wavelength. The maximum pulse energy that can be transmitted through a particular fiber is limited by the onset of laser-induced breakdown and damage mechanisms. Laser breakdown at the fiber entrance face is often the first limiting process to be encountered, but other mechanisms can result in catastrophic damage at either fiber face, within the initial entry segment of the fiber, and at other internal sites along the fiber path. In the course of their studies they have examined a number of factors that govern the relative importance of different mechanisms, including laser characteristics, the design and alignment of injection optics, fiber end-face preparation, and fiber routing. The present study emphasizes the important criteria for injection optics in high-intensity fiber transmission, and illustrates the opportunities that now exist for innovative designs of optics to meet these criteria. The consideration of diffractive optics to achieve desired injection criteria began in 1993, and they have evaluated a progression of designs since that time. In the present study, two recent designs for injection optics are compared by testing a sufficient number of fibers with each design to establish statistics for the onset of laser-induced breakdown and damage. In this testing they attempted to hold constant other factors that can influence damage statistics. Both designs performed well, although one was less successful in meeting all injection criteria and consequently showed a susceptibility to a particular damage process.

  17. Application of the Speed-Duration Relationship to Normalize the Intensity of High-Intensity Interval Training

    PubMed Central

    Ferguson, Carrie; Wilson, John; Birch, Karen M.; Kemi, Ole J.

    2013-01-01

    The tolerable duration of continuous high-intensity exercise is determined by the hyperbolic Speed-tolerable duration (S-tLIM) relationship. However, application of the S-tLIM relationship to normalize the intensity of High-Intensity Interval Training (HIIT) has yet to be considered, with this the aim of present study. Subjects completed a ramp-incremental test, and series of 4 constant-speed tests to determine the S-tLIM relationship. A sub-group of subjects (n = 8) then repeated 4 min bouts of exercise at the speeds predicted to induce intolerance at 4 min (WR4), 6 min (WR6) and 8 min (WR8), interspersed with bouts of 4 min recovery, to the point of exercise intolerance (fixed WR HIIT) on different days, with the aim of establishing the work rate that could be sustained for 960 s (i.e. 4×4 min). A sub-group of subjects (n = 6) also completed 4 bouts of exercise interspersed with 4 min recovery, with each bout continued to the point of exercise intolerance (maximal HIIT) to determine the appropriate protocol for maximizing the amount of high-intensity work that can be completed during 4×4 min HIIT. For fixed WR HIIT tLIM of HIIT sessions was 399±81 s for WR4, 892±181 s for WR6 and 1517±346 s for WR8, with total exercise durations all significantly different from each other (P<0.050). For maximal HIIT, there was no difference in tLIM of each of the 4 bouts (Bout 1: 229±27 s; Bout 2: 262±37 s; Bout 3: 235±49 s; Bout 4: 235±53 s; P>0.050). However, there was significantly less high-intensity work completed during bouts 2 (153.5±40. 9 m), 3 (136.9±38.9 m), and 4 (136.7±39.3 m), compared with bout 1 (264.9±58.7 m; P>0.050). These data establish that WR6 provides the appropriate work rate to normalize the intensity of HIIT between subjects. Maximal HIIT provides a protocol which allows the relative contribution of the work rate profile to physiological adaptations to be considered during alternative intensity-matched HIIT protocols. PMID:24244266

  18. Effects of different light wavelengths from LEDs on oxidative stress and apoptosis in olive flounder (Paralichthys olivaceus) at high water temperatures.

    PubMed

    Kim, Bong-Seok; Jung, Seo Jin; Choi, Young Jae; Kim, Na Na; Choi, Cheol Young; Kim, Jae-Woo

    2016-08-01

    We investigated how different light spectra affect thermal stress in olive flounder (Paralichthys olivaceus), using light emitting diodes (LEDs; blue, 450 nm; green, 530 nm; red, 630 nm) at two intensities (0.3 and 0.5 W/m(2)) at relatively high water temperatures (25 and 30 °C, compared to a control condition of 20 °C). We measured the expression and activity of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), and the levels of plasma hydrogen peroxide (H2O2) and lipid peroxidation (LPO). Furthermore, the levels and mRNA expression of caspase-3 were measured, and terminal transferase dUTP nick end labeling (TUNEL) assays of liver and comet assays were performed. The expression and activity of antioxidant enzymes, as well as plasma H2O2 and LPO levels were significantly higher after exposure to high temperatures, and significantly lower after exposure to green and blue light. Caspase-3 levels and mRNA expression showed a similar pattern. The TUNEL assay showed that apoptosis markedly increased at higher water temperatures, compared with the 20 °C control. In contrast, green light irradiation decreased apoptosis rate. Furthermore, the comet assays showed that nuclear DNA damage was caused by thermal stress, and that green light irradiation played a role in partially preventing this damage. Overall, these results suggest that light with green and blue wavelengths can reduce both high temperature-induced oxidative stress and apoptosis, and that particularly green light is efficient for this. Therefore, green light can play a role in protecting in olive flounder from thermal stress damage. PMID:27320868

  19. Commissioning the new high power rf system for the AGS with high intensity beam

    SciTech Connect

    Brennan, J.M.; Ciardullo, D.J.; Deng, D.P; Hayes, T.; Onillon, E.; Otis, A.; Sanders, R.T.; Zaltsman, A.

    1994-08-01

    A new high power rf system has been installed in the AGS in order to raise the beam loading limit to beyond 6 {times} 10{sup 13} protons per pulse. The old system was limited to 2.2 {times} 10{sup l3} ppp by: available real power, multi-loop instability, and transient beam loading during batch filling from the Booster. The key components of the new system are: new power amplifiers in the tunnel using the Thomson-CSF TH573 300kW tetrode, rf feedback around the power stage, and reduction of the 10 cavities` R/Q by 1.8 by additional gap capacitors. Commissioning of the new rf system with high intensity beam is described. The intensity goal for the 1994 running period is 4 {times} 10{sup 13} ppp. To date, 3.7 {times} 10{sup 13} ppp has been achieved.

  20. The effect of progressive high-intensity inspiratory muscle training and fixed high-intensity inspiratory muscle training on the asymmetry of diaphragm thickness in stroke patients

    PubMed Central

    Jung, Ju-hyeon; Kim, Nan-soo

    2015-01-01

    [Purpose] This study investigated the effects of progressive load and fixed load high-intensity inspiratory muscle training on the asymmetry of diaphragm thickness in stroke patients. [Subjects] Twenty-one stroke patients were assigned to one of three groups: progressive load high-intensity inspiratory muscle training (n = 8), fixed load high-intensity inspiratory muscle training (n = 6), and controls (n = 7). [Methods] The progressive load and fixed load high-intensity inspiratory muscle training participants undertook an exercise program for 20 minutes, three times weekly, for 6 weeks. After each session, diaphragm thickness was measured using ultrasonography. The diaphragm asymmetry ratio and diaphragm thickening ratio were standardized using a formula. [Results] After intervention, the diaphragm asymmetry ratio significantly differed among the three groups, and the diaphragm asymmetry ratio significantly increased in the control group. A significant increase was identified in the diaphragm thickening ratio within the progressive load and fixed load high-intensity inspiratory muscle training groups. [Conclusion] Progressive load and fixed load high-intensity inspiratory muscle training decreased the asymmetry of diaphragm thickness in stroke patients; this effect, in turn, increased the diaphragm thickening ratio in stroke patients. The two interventions examined here should be selectively applied to individuals in the clinical field. PMID:26644689

  1. Recent progress and future prospect of high-performance near-UV based white LEDs: from ECO lighting to medical application

    NASA Astrophysics Data System (ADS)

    Taguchi, Tsunemasa

    2009-08-01

    Near ultraviolet (n-UV) LED-based white light source (LS) can provide the excellent illuminant properties that show high-luminous efficacy (Le>80 lm/W) of radiation and high-color rendering index (CRI or Ra>99). Recent progress and future advantages of the n-UV white LED technology on the basis of our direct flip-chip bonding and stacked multi-layer structure methods will be described. Particularly, the fabrication process, and electrical and illuminant properties in the low-correlated color temperature (CCT or Tc~3452K) white LED with a high-luminous flux (~500 lm/PKG) are discussed, and its lighting and medical applications such as ecological street lighting and gastrointestinal digestive endoscope will be introduced. Furthermore, a color tunable white LS which is composed of multi-phosphor conversion LEDs and its characterization are described. Differences on the quality of light between the n-UV white LED and the conventional blue-YAG white LED will be clarified.

  2. Intensity Mapping of Molecular Gas at High Redshift

    NASA Astrophysics Data System (ADS)

    Bower, Geoffrey; Keating, Garrett; Marrone, Dan; DeBoer, David; Chang, Tzu-Ching; Chen, Ming-Tang; Jiang, Homin; Koch, Patrick; Kubo, Derek; Li, Chao-Te; Lin, K. Y.; Srinivasan, Ranjani; Darling, Jeremy

    2015-08-01

    The origin and evolution of structure in the Universe is one of the major challenges of observational astronomy. How and when did the first stars and galaxies form? How does baryonic structure trace the underlying dark matter? A multi-wavelength, multi-tool approach is necessary to provide the complete story or the evolution of structure in the Universe. Intensity mapping, which relies on the ability to detect many objects at once through their integrated emission rather than direct detection of individual objects, is a critical part of this mosaic. Intensity mapping provides a window on lower luminosity objects that cannot be detected individually but that collectively drive important processes. In particular, our understanding of the molecular gas component of massive galaxies is being revolutionized by ALMA and EVLA but the population of smaller, star-forming galaxies, which provide the bulk of star formation cannot be individually probed by these instruments.In this talk, I will summarize two intensity mapping experiments to detect molecular gas through the carbon monoxide (CO) rotational transition. We are currently completing sensitive observations with the Sunyaev-Zel'dovic Array (SZA) telescope at a wavelength of 1 cm that are sensitive to emission at redshifts 2.3 to 3.3. The SZA experiments sets strong limits on models for the CO emission and demonstrates the ability to reject foregrounds and telescope systematics in very deep integrations. I also describe the development of an intensity mapping capability for the Y.T. Lee Array, a 13-element interferometer located on Mauna Loa. In its first phase, this project focuses on detection of CO at redshifts 2.3 - 3.3 with detection via power spectrum and cross-correlation with other surveys. The project includes a major technical upgrade, a new digital correlator and IF electronics component to be deployed in 2015/2016. The Y.T. Lee Array observations will be more sensitive and extend to larger angular scales

  3. Driving Down HB-LED Costs. Implementation of Process Simulation Tools and Temperature Control Methods of High Yield MOCVD Growth

    SciTech Connect

    Quinn, William

    2012-04-30

    The overall objective of this multi-faceted program is to develop epitaxial growth systems that meet a goal of 75% (4X) cost reduction in the epitaxy phase of HB-LED manufacture. A 75% reduction in yielded epitaxy cost is necessary in order to achieve the cost goals for widespread penetration of HB-LED's into back-lighting units (BLU) for LCD panels and ultimately for solid-state lighting (SSL). To do this, the program will address significant improvements in overall equipment Cost of Ownership, or CoO. CoO is a model that includes all costs associated with the epitaxy portion of production. These aspects include cost of yield, capital cost, operational costs, and maintenance costs. We divide the program into three phases where later phases will incorporate the gains of prior phases. Phase one activities are enabling technologies. In collaboration with Sandia National Laboratories we develop a Fluent-compatible chemistry predictive model and a set of mid-infrared and near-ultraviolet pyrometer monitoring tools. Where previously the modeling of the reactor dynamics were studied within FLUENT alone, here, FLUENT and Chemkin are integrated into a comprehensive model of fluid dynamics and the most advanced transport equations developed for Chemkin. Specifically, the Chemkin model offered the key reaction terms for gas-phase nucleation, a key consideration in the optimization of the MOCVD process. This new predictive model is used to design new MOCVD reactors with optimized growth conditions and the newly developed pyrometers are used monitor and control the MOCVD process temperature to within 0.5°C run-to-run and within each wafer. This portion of the grant is in collaboration with partners at Sandia National Laboratories. Phase two activities are continuous improvement projects which extend the current reactor platform along the lines of improved operational efficiency, improved systems control for throughput, and carrier modifications for increased yield

  4. Nakagami imaging for detecting thermal lesions induced by high-intensity focused ultrasound in tissue.

    PubMed

    Rangraz, Parisa; Behnam, Hamid; Tavakkoli, Jahan

    2014-01-01

    High-intensity focused ultrasound induces focalized tissue coagulation by increasing the tissue temperature in a tight focal region. Several methods have been proposed to monitor high-intensity focused ultrasound-induced thermal lesions. Currently, ultrasound imaging techniques that are clinically used for monitoring high-intensity focused ultrasound treatment are standard pulse-echo B-mode ultrasound imaging, ultrasound temperature estimation, and elastography-based methods. On the contrary, the efficacy of two-dimensional Nakagami parametric imaging based on the distribution of the ultrasound backscattered signals to quantify properties of soft tissue has recently been evaluated. In this study, ultrasound radio frequency echo signals from ex vivo tissue samples were acquired before and after high-intensity focused ultrasound exposures and then their Nakagami parameter and scaling parameter of Nakagami distribution were estimated. These parameters were used to detect high-intensity focused ultrasound-induced thermal lesions. Also, the effects of changing the acoustic power of the high-intensity focused ultrasound transducer on the Nakagami parameters were studied. The results obtained suggest that the Nakagami distribution's scaling and Nakagami parameters can effectively be used to detect high-intensity focused ultrasound-induced thermal lesions in tissue ex vivo. These parameters can also be used to understand the degree of change in tissue caused by high-intensity focused ultrasound exposures, which could be interpreted as a measure of degree of variability in scatterer concentration in various parts of the high-intensity focused ultrasound lesion. PMID:24264647

  5. Effect of electrophotographic processes on print quality in LED printers

    NASA Astrophysics Data System (ADS)

    Wyhof, John R.

    1990-08-01

    The advantage of LED electrophotographic page printers is closely linked to the the process parameters of the printer. The electrical and mechanical processes and material properties were analyzed with respect to the affect on the print quality. Most critical to the print quality for the LED array printer is the constancy of the light intensity since the elements in the array are each independent light sources. It was found that the spot size can change significantly if the light intensity varies. Halftone printing uses the spot size to space size ratio to create the grayscale. The light intensity variation between elements can be 20 in non-compensated LED head arrays. If the need for light intensity compensation can be eliminated then a significant cost reduction in the LED head can be achieved. However the parameters of the basic electrophotographic processes must be carefully selected to assure a constant spot size and optimum print quality. The development method toner properties and the portion of the photoreceptor discharge curve used have the strongest influence on the spot size and halftone print quality. Transfer fusing and mechanical parameters have minimal effect. 1. LED PRINTING PROCESS The advantages of the LED printing process for high speed electrophotographic printers are well known. 1 Recently several printer manufacturers have introduced electrophotographic LED printers in the lower speed range. When compared to the scanning laser beam or liquid crystal

  6. Towards phasing using high X-ray intensity.

    PubMed

    Galli, Lorenzo; Son, Sang-Kil; Barends, Thomas R M; White, Thomas A; Barty, Anton; Botha, Sabine; Boutet, Sébastien; Caleman, Carl; Doak, R Bruce; Nanao, Max H; Nass, Karol; Shoeman, Robert L; Timneanu, Nicusor; Santra, Robin; Schlichting, Ilme; Chapman, Henry N

    2015-11-01

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential 'bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed. PMID:26594370

  7. Towards phasing using high X-ray intensity

    DOE PAGESBeta

    Galli, Lorenzo; Son, Sang -Kil; Barends, Thomas R. M.; White, Thomas A.; Barty, Anton; Botha, Sabine; Boutet, Sébastien; Caleman, Carl; Doak, R. Bruce; Nanao, Max H.; et al

    2015-09-30

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential `bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. In conclusion, a pattern sorting schememore » is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.« less

  8. High intensity proton acceleration at the Brookhaven AGS -- An update

    SciTech Connect

    Ahrens, L.; Alessi, J.; Blaskiewicz, M.

    1997-07-01

    The AGS accelerator complex is into its third year of 60+ {times} 10{sup 12} (teraproton = Tp) per cycle operation. The hardware making up the complex as configured in 1997 is briefly mentioned. The present level of accelerator performance is discussed. This includes beam transfer efficiencies at each step in the acceleration process, i.e. losses; which are a serious issue at this intensity level. Progress made in understanding beam behavior at the Linac-to-Booster (LtB) injection, at the Booster-to-AGS (BtA) transfer as well as across the 450 ms AGS accumulation porch is presented. The state of transition crossing, with the gamma-tr jump is described. Coherent effects including those driven by space charge are important at all of these steps.

  9. Towards phasing using high X-ray intensity

    PubMed Central

    Galli, Lorenzo; Son, Sang-Kil; Barends, Thomas R. M.; White, Thomas A.; Barty, Anton; Botha, Sabine; Boutet, Sébastien; Caleman, Carl; Doak, R. Bruce; Nanao, Max H.; Nass, Karol; Shoeman, Robert L.; Timneanu, Nicusor; Santra, Robin; Schlichting, Ilme; Chapman, Henry N.

    2015-01-01

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential ‘bleaching’ of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed. PMID:26594370

  10. HIGH INTENSITY LOW-ENERGY POSITRON SOURCE AT JEFFERSON

    SciTech Connect

    Serkan Golge, Bogdan Wojtsekhowski, Branislav Vlahovic

    2012-07-01

    We present a novel concept of a low-energy e{sup +} source with projected intensity on the order of 10{sup 10} slow e{sup +}/s. The key components of this concept are a continuous wave e{sup -} beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of e{sup +} into a field-free area through a magnetic plug for moderation in a cryogenic solid. Components were designed in the framework of GEANT4-based (G4beamline) Monte Carlo simulation and TOSCA magnetic field calculation codes. Experimental data to demonstrate the effectiveness of the magnetic plug is presented.

  11. Towards phasing using high X-ray intensity

    SciTech Connect

    Galli, Lorenzo; Son, Sang-Kil; Barends, Thomas R. M.; White, Thomas A.; Barty, Anton; Botha, Sabine; Boutet, Sébastien; Caleman, Carl; Doak, R. Bruce; Nanao, Max H.; Nass, Karol; Shoeman, Robert L.; Timneanu, Nicusor; Santra, Robin; Schlichting, Ilme; Chapman, Henry N.

    2015-09-30

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential `bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.

  12. Towards phasing using high X-ray intensity

    SciTech Connect

    Galli, Lorenzo; Son, Sang -Kil; Barends, Thomas R. M.; White, Thomas A.; Barty, Anton; Botha, Sabine; Boutet, Sébastien; Caleman, Carl; Doak, R. Bruce; Nanao, Max H.; Nass, Karol; Shoeman, Robert L.; Timneanu, Nicusor; Santra, Robin; Schlichting, Ilme; Chapman, Henry N.

    2015-09-30

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential `bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. In conclusion, a pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.

  13. Laser imprint suppression using high-Z layers at high foot intensities

    NASA Astrophysics Data System (ADS)

    Karasik, Max; Aglitskiy, Y.; Serlin, V.; Weaver, J. L.; Bates, J. W.; Phillips, L. S.

    2006-10-01

    Laser imprint experiments are carried out on the Nike KrF laser with induced spatial incoherence (ISI) smoothing. Most of the imprint occurs during the initial low-intensity (``foot'') part of the pulse, which is necessary to compress the target to achieve high gain. It has been found previously that a thin high-Z overcoat on the laser side of the target can be effective in suppressing imprint [S. P. Obenschain et al. Phys. Plasmas 9, 2234 (2002)]. The present experiments are designed to extend this method to higher foot intensities (˜10^13 W/cm^2), approaching those of the current high gain pellet designs. Measurements of Raleigh-Taylor (RT) amplified areal mass non-uniformity are made by face-on x-ray radiography using Bragg reflection from a curved crystal coupled to an x-ray streak camera. X-ray flux from the high-Z layer is monitored using absolutely calibrated time-resolved x-ray spectrometers. Simultaneous side-on radiography using a curved crystal allows target trajectory measurement for comparison with simulations. The effect of the high-Z layers of varying thicknesses on ISI imprint as well as re-imposed ripple growth will be presented for two different materials (Au and Pd). This work is supported by US DOE/NNSA.

  14. LEDs for Efficient Energy

    ERIC Educational Resources Information Center

    Guerin, David A.

    1978-01-01

    Light-emitting diodes (LEDs) are described and three classroom experiments are given, one to prove the, low power requirements and efficiency of LEDs, an LED on-off detector circuit, and the third an LED photoelectric smoke detector. (BB)

  15. High-intensity exercise causes greater irisin response compared with low-intensity exercise under similar energy consumption.

    PubMed

    Tsuchiya, Yoshifumi; Ando, Daisuke; Goto, Kazushige; Kiuchi, Masataka; Yamakita, Mitsuya; Koyama, Katsuhiro

    2014-01-01

    Irisin is mainly released from skeletal muscle (myocytes) and promotes thermogenesis by browning of the white adipose tissue. Although exercise has been shown to increase irisin concentration in blood and myocytes via up-regulation peroxisome proliferator receptor γ coactivator-1α (PGC-1α) expression, the influence of exercise intensity on irisin secretion remains unclear. Therefore, we determined circulating irisin responses following a single bout of running at different intensities. Six sedentary males underwent treadmill running under two different conditions: a low-intensity (40% of VO2max) exercise trial (LIE) or a high-intensity (80% of VO2max) exercise trial (HIE). The exercises in LIE and HIE were lasted for 20 and 40 min, respectively. All subjects underwent the two trials on separate days, and a randomized cross-over design was used. Blood samples were collected before (Pre) and immediately after exercise, at 3, 6, and 19 h after exercise. Energy consumption during exercise did not significantly differ between the two trials. HIE significantly increased blood lactate and serum lactate dehydrogenase levels (P < 0.05). Compared with pre-exercise levels, the irisin concentrations were elevated at 6 h (18% increase) and 19 h (23% increase) after HIE, but significantly decreased after LIE. The relative irisin concentrations (compared with pre-exercise levels) were significantly greater in HIE than in LIE immediately after exercise, and at 6 and 19 h after exercise (P < 0.05). These findings suggest that irisin secretion after acute running exercise is affected by exercise intensity, independent of energy consumption. PMID:24910199

  16. Denali Geographic 2012 : A University led scientific field experience for High School students at the Alaska Summer Research Academy

    NASA Astrophysics Data System (ADS)

    Shipman, J. S.; Webley, P. W.; Burke, S.; Chebul, E.; Dempsey, A.; Hastings, H.; Terry, R.; Drake, J.

    2012-12-01

    The Alaska Summer Research Academy (ASRA) annually provides the opportunity for ~150 exceptional high school students to engage in scientific exploration at the university level. In July 2012, University of Alaska Fairbanks instructors led a two-week long ASRA module, called 'Denali Geographic', where eight student participants from across the USA and Canada learned how to observe changes in the natural world and design their own experiments for a field expedition to Denali National Park and Preserve, with assistance from the National Park Service. Each student designed an experiment/observational project prior to the expedition to investigate changes across the expanse of the park. Projects included wildlife documentation; scat and track observations; soil ph and moisture with elevation and vegetation changes; wildflowers species distribution; waterborne insect populations; atmospheric pressure and temperature variations; construction of sustainable buildings to minimize human impact on the park; and park geology comparisons between outcrop and distal stream deposits. The students learned how to design experiments, purchase supplies needed to conduct the work, and select good locations in which to sample in the park. Students used equipment such as GPS to mark field locations; a range finder to determine distance from wildlife; a hygrometer for temperature and pressure; nets and sorting equipments to analyze insects; and the preparation of Plaster of Paris for creating casts of animal tracks. All observations were documented in their field notebooks and blog entries made to share their experiences. Day excursions as part of the module included Poker Flats Research Range, where students learned about the use of unmanned aerial vehicles in scientific exploration; Alaska Volcano Observatory, where students learned about volcanic hazards in Alaska and the North Pacific; Chena Hot Springs and the Ice Museum, where students learned about thermal imaging using a Forward

  17. High frequency intensity fluctuations: Comparison of theory with experiment

    NASA Astrophysics Data System (ADS)

    Lutz, Steven D.; Bradley, David L.; Culver, R. Lee

    2003-10-01

    Amplitude fluctuations were measured during August 2002 near San Diego using 20 and 40 kHz cw and fm signals. Source-receiver separation was 1 km; source depths were 10 m to 67 m; receiver hydrophone depths were 44 m to 217 m. A 15-element chain of CTD sensors was towed to measure horizontal temperature and salinity variation with 1m resolution. Theory exists explaining the relationship between amplitude fluctuations and acoustic frequency, source-receiver separation, and index of refraction patch size in the ocean [e.g., Flatte et al., Sound Transmission Through a Fluctuating Ocean (Cambridge Press, 1979); Uscinsky et al., ``Intensity Fluctuations. Part 1: Theory,'' J. Acoust. Soc. Am. 74 (1983)]. However, the amplitude fluctuations we observe are much lower than that predicted by theory [J. Acoust. Soc. Am. 113, 2333 (2003)]. Our frequencies are 1 to 2 orders of magnitude higher than those used in the experiments upon which the theory is based and our propagation ranges are considerable shorter 1 km versus many km. Results will be discussed from a more detailed analysis of the ray path locations within the water column activity (Langmuir cell formation and internal wave passage).

  18. A plasma generator utilizing the high intensity ASTROMAG magnets

    NASA Technical Reports Server (NTRS)

    Sullivan, James D.; Post, R. S.; Lane, B. G.; Tarrh, J. M.

    1986-01-01

    The magnet configuration for the proposed particle astrophysics magnet facility (ASTROMAG) on the space station includes a cusp magnetic field with an intensity of a few tesla. With these large magnets (or others) located in the outer ionosphere, many quite interesting and unique plasma physics experiments become possible. First there are studies utilizing the magnet alone to examine the supersonic, sub-Alfvenic interaction with the ambient medium; the scale length for the magnet perturbation is approx. 20 m. The magnetic field geometry when combined with the Earth's and their relative motion will give rise to a host of plasma phenomena: ring nulls, x-points, ion-acoustic and lower-hybrid shocks, electron heating (possible shuttle glow without a surface) launching of Alfvenwaves, etc. Second, active experiments are possible for a controlled study of fundamental plasma phenomena. A controlled variable species plasma can be made by using an RF ion source; use of two soft iron rings placed about the line cusp would give an adequate resonance zone (ECH or ICH) and a confining volume suitable for gas efficiency. The emanating plasma can be used to study free expansion of plasma along and across field lines (polar wind), plasma flows around the space platform, turbulent mixing in the wake region, long wavelength spectrum of convecting modes, plasma-dust interactions, etc.

  19. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  20. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  1. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  2. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  3. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  4. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  5. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  6. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  7. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  8. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  9. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  10. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  11. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  12. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  13. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  14. Effect of Short-Term, High-Intensity Exercise on Anaerobic Threshold in Women.

    ERIC Educational Resources Information Center

    Evans, Blanche W.

    This study investigated the effects of a six-week, high-intensity cycling program on anaerobic threshold (AT) in ten women. Subjects trained four days a week using high-intensity interval-type cycle exercises. Workouts included six 4-minute intervals cycling at 85 percent maximal oxygen uptake (VO sub 2 max), separated by 3-minute intervals of…

  15. Color temperature tunable white light LED system

    NASA Astrophysics Data System (ADS)

    Speier, Ingo; Salsbury, Marc

    2006-08-01

    Efficient white light LED systems with continuously tunable color temperature (CT) over a range of 3000 K to 6500 K are reviewed. Typically, white light sources have a fixed CT and color rendering index (CRI). White light with user-specified color temperatures is currently generated by solid-state systems with red green blue ("R/G/B"), red green blue amber ("R/G/B/A"), and warm white cool white ("WW/CW") LED combinations, but their performance is suboptimal for architectural lighting applications. We propose and discuss an LED module with a combination of warm white, green and blue ("WW/G/B") LEDs. In this scenario, the white LEDs have fixed intensity, while the blue and green LED intensities are adjusted to shift the LED module chromaticity along the blackbody locus. We also propose and discuss an LED module with a combination of red, green, blue, and cool white ("R/G/B/CW") LEDs. The white LEDs still have a fixed intensity, while the intensities of the red, green, and blue LEDs are again adjusted to shift the LED module chromaticity along the blackbody locus. The white LEDs ensure that an improved CRI is maintained in comparison to a simple "R/G/B" solution.

  16. Experimental observation of anomalous high harmonics at low intensities

    NASA Astrophysics Data System (ADS)

    Valentin, C.; Kazamias, S.; Douillet, D.; Grillon, G.; Lefrou, T.; Augé, F.; Sebban, S.; Balcou, P.

    A variety of complex phenomena occurs when an ultra-short laser pulse interacts with atoms in the 1013 W/cm2 range: non-sequential ionisation, electron recollision, and Freeman resonances. We show that high-harmonic spectra obtained experimentally in this parameter range also display anomalous features, which are difficult to understand in the framework of the three-step, semiclassical model. The results of a systematic study of these high harmonics generated in argon, xenon, and krypton are presented. From the experimental curves, complex high-order harmonic generation phenomena are discussed.

  17. Laboratory Astrophysics Using High Intensity Particle and Photon Beams

    SciTech Connect

    Chen, Pisin

    2001-12-12

    History has shown that the symbiosis between direct observations and laboratory studies is instrumental in the progress of astrophysics. Recent years have seen growing interests in the laboratory investigation of astrophysical phenomena that can be addressed by high densities and advancement of technologies in lasers as well as high-energy particle beams. We will give examples on how frontier phenomena such as black holes, supernovae, gamma ray bursts, ultra high-energy cosmic rays, etc., can be investigated in the laboratory setting. Finally, we describe a possible laboratory astrophysics facility to be developed at SLAC.

  18. Laboratory Astrophysics Using High Intensity Particle and Photon Beams

    SciTech Connect

    Chen, Pisin

    2009-12-12

    History has shown that the symbiosis between direct observations and laboratory studies is instrumental in the progress of astrophysics. Recent years have seen growing interests in the laboratory investigation of astrophysical phenomena that can be addressed by high densities and advancement of technologies in lasers as well as high-energy particle beams. We will give examples on how frontier phenomena such as black holes, supernovae, gamma ray bursts, ultra high-energy cosmic rays, etc., can be investigated in the laboratory setting. Finally, we describe a possible laboratory astrophysics facility to be developed at SLAC.

  19. Non-invasive transcranial brain ablation with high-intensity focused ultrasound.

    PubMed

    Jenne, Jürgen W

    2015-01-01

    The idea to ablate brain tissue with high-intensity focused ultrasound (HIFU) in a highly precise and localized manner is relatively old. For HIFU tissue ablation, ultrasound (US) waves are concentrated to a focal point. Due to US absorption, the focal area will be heated and consequently thermally destroyed. The spatial accuracy of the non-invasive procedure and the sharp delineation of the induced tissue lesions have led to the term 'focused ultrasound surgery' (FUS). The major obstacle for HIFU ablation in the brain is the skull bone, which absorbs most of the US energy and disturbs the focused US field. The development of large-sized phased array US transducers and adaptive focusing techniques based on computed tomography images have allowed these difficulties to be overcome. With the combination of FUS and MR-imaging and MR-thermometry (MR-guided Focused Ultrasound Surgery, MRgFUS), real-time therapy guidance and control has been established. The safety, feasibility and effectiveness of transcranial MRgFUS were investigated in four initial clinical studies including 4 to 15 patients each. In the first study, which dealt with the treatment of inoperable recurrent glioblastoma, MR was used to monitor localized tissue heating, but no tissue ablation was possible due to technical restrictions of the treatment setup. With improved equipment, the precise induction of thermal lesions in the target area was achieved in studies on neuropathic pain and essential tremor. An instantaneous and persistent significant improvement of disease symptoms was observed in most patients. However, there were serious adverse effects in two cases, where intracranial hemorrhages appeared due to the induction of cavitation. Based on these encouraging clinical results, more extensive clinical studies have been initiated. Transcranial MRgFUS is a fast-growing field of neurological research with high clinical potential. PMID:25531666

  20. High-intensity attosecond high-order harmonic generation driven by a synthesized laser field

    SciTech Connect

    Zeng Zhinan; Li Ruxin; Xie Xinhua; Xu Zhizhan

    2004-11-01

    The scheme of high-intensity attosecond high-order harmonic generation driven by a synthesized laser field is proposed. The synthesized laser field is obtained by an appropriate superposition of a few-cycle laser pulse and a relatively long pulse of several tens of femtoseconds. Calculated results show that the intensity of the attosecond high-order harmonic pulse in helium driven by the synthesized laser field with a 8.8x10{sup 13} W/cm{sup 2}/5 fs laser pulse and a 3.51x10{sup 14} W/cm{sup 2}/50 fs laser pulse is several orders of magnitude higher than that driven by a single 8.8x10{sup 13} W/cm{sup 2}/5 fs laser pulse, and it is even stronger than that driven by a single 7.9x10{sup 14} W/cm{sup 2}/5 fs laser pulse, although the single and the synthesized pulses have the same peak electric-field strength.

  1. The study towards high intensity high charge state laser ion sources.

    PubMed

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible. PMID:24593615

  2. High-time resolution and size-segregated elemental composition in high-intensity pyrotechnic exposures.

    PubMed

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F; Lucarelli, Franco; Nava, Silvia; Chiari, Massimo; Calzolai, Giulia

    2012-11-30

    Typical of festivals in Eastern Spain, mascletàs are high-intensity pyrotechnic events where thousands of firecrackers are burnt in an intense, rapid episode that generates short-lived heavy aerosol clouds. High temporal resolution and size distribution characterisation of aerosol components were performed to evaluate the effects of the brief (<30 min) and acute exposure on the spectators present. Very high concentrations of firework specific elements, especially in the fine fraction, were reached during mascletàs, with values of about 500 μg/m(3) for K and 300 μg/m(3) for Cl. Sr, Al, Mg, Ba, Cu, Co, Zn, and Pb concentration increase factors of more than 100 (1000 for Sr and Ba) were observed in the fine fraction with respect to background levels. Crustal origin elements, like Ca, Fe, Si, Ti, also showed an important concentration rise (~10 times above background levels) but this is due to dust resuspension by pyrotechnic explosions. The crustal components are mainly in the coarse mode (>90% elemental mass), between 2 and 3 μm. Most firework related metals are concentrated in the submicrometric region (>80%) with a trimodal size distribution. This may be interesting to epidemiologists given the toxic effects that such fine, metal-rich particles can have on human health. PMID:23026448

  3. Liquid lithium target as a high intensity, high energy neutron source

    DOEpatents

    Parkin, Don M.; Dudey, Norman D.

    1976-01-01

    This invention provides a target jet for charged particles. In one embodiment the charged particles are high energy deuterons that bombard the target jet to produce high intensity, high energy neutrons. To this end, deuterons in a vacuum container bombard an endlessly circulating, free-falling, sheet-shaped, copiously flowing, liquid lithium jet that gushes by gravity from a rectangular cross-section vent on the inside of the container means to form a moving web in contact with the inside wall of the vacuum container. The neutrons are produced via break-up of the beam in the target by stripping, spallation and compound nuclear reactions in which the projectiles (deuterons) interact with the target (Li) to produce excited nuclei, which then "boil off" or evaporate a neutron.

  4. High-output LED based on p-n Al(x)Ga(1-x)As(Si) structures of varying composition

    NASA Astrophysics Data System (ADS)

    Bednarskii, V. V.; Gaft, A. E.; Kovalenko, V. F.; Lisovenko, V. D.; Litvin, A. A.

    Factors affecting the emission output of p-n GaAs(Si) structures are investigated. It is found that increasing the p-layer thickness, doping with isovalent indium impurity, and decreasing the GaAs substrate thickness and electron concentration result in increased emission intensity. It is demonstrated that a further increase in the emission power of p-n Al(x)Ga(1-x)As(Si, In) structures (up to 7-8 mW) for a LED current of 100 mA) can be achieved by creating a surface microrelief and applying an antireflection anodic oxide coating to the mesa structures.

  5. Monolithically Integrated μLEDs on Silicon Neural Probes for High-Resolution Optogenetic Studies in Behaving Animals.

    PubMed

    Wu, Fan; Stark, Eran; Ku, Pei-Cheng; Wise, Kensall D; Buzsáki, György; Yoon, Euisik

    2015-12-16

    We report a scalable method to monolithically integrate microscopic light emitting diodes (μLEDs) and recording sites onto silicon neural probes for optogenetic applications in neuroscience. Each μLED and recording site has dimensions similar to a pyramidal neuron soma, providing confined emission and electrophysiological recording of action potentials and local field activity. We fabricated and implanted the four-shank probes, each integrated with 12 μLEDs and 32 recording sites, into the CA1 pyramidal layer of anesthetized and freely moving mice. Spikes were robustly induced by 60 nW light power, and fast population oscillations were induced at the microwatt range. To demonstrate the spatiotemporal precision of parallel stimulation and recording, we achieved independent control of distinct cells ∼ 50 μm apart and of differential somato-dendritic compartments of single neurons. The scalability and spatiotemporal resolution of this monolithic optogenetic tool provides versatility and precision for cellular-level circuit analysis in deep structures of intact, freely moving animals. PMID:26627311

  6. Spatial shaping of intense femtosecond beams for the generation of high-energy attosecond pulses

    NASA Astrophysics Data System (ADS)

    Constant, E.; Dubrouil, A.; Hort, O.; Petit, S.; Descamps, D.; Mével, E.

    2012-04-01

    We generate high-order harmonics with a spatially shaped TW laser beam. We present and analyse in detail a new approach for shaping an intense laser field to a flat-top intensity profile near focus. We show that this approach is well adapted for high harmonic generation with high-energy fundamental pulses and highlight the possibilities for generating high-energy attosecond pulses.

  7. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    SciTech Connect

    Not Available

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

  8. Device for providing high-intensity ion or electron beam

    DOEpatents

    McClanahan, Edwin D.; Moss, Ronald W.

    1977-01-01

    A thin film of a low-thermionic-work-function material is maintained on the cathode of a device for producing a high-current, low-pressure gas discharge by means of sputter deposition from an auxiliary electrode. The auxiliary electrode includes a surface with a low-work-function material, such as thorium, uranium, plutonium or one of the rare earth elements, facing the cathode but at a disposition and electrical potential so as to extract ions from the gas discharge and sputter the low-work-function material onto the cathode. By continuously replenishing the cathode film, high thermionic emissions and ion plasmas can be realized and maintained over extended operating periods.

  9. Intensities of high-energy cosmic rays at Mount Kanbala

    NASA Technical Reports Server (NTRS)

    Ren, J. R.; Kuang, H. H.; Huo, A. X.; Lu, S. L.; Su, S.; Wang, Y. X.; Xue, Y. G.; Wang, C. R.; He, M.; Zhang, N. J.

    1985-01-01

    The energy spectra of atmospheric cosmic rays at Mt. Kanbala (520 g/sq cm.) are measured with emulsion chambers. The power indexes of the spectra are values of about 2.0 for both gamma-rays and hadrons. Those fluxes are consistent with the ones expected from the model of primary cosmic rays with heavy nuclei of high content in the energy around 10 to the 15th power eV.

  10. High-Intensity High-order Harmonics Generated from Low-Density Plasma

    SciTech Connect

    Ozaki, T.; Bom, L. B. Elouga; Abdul-Hadi, J.; Ganeev, R. A.; Haessler, S.; Salieres, P.

    2009-07-25

    We study the generation of high-order harmonics from lowly ionized plasma, using the 10 TW, 10 Hz laser of the Advanced Laser Light Source (ALLS). We perform detailed studies on the enhancement of a single order of the high-order harmonic spectrum generated in plasma using the fundamental and second harmonic of the ALLS beam line. We observe quasi-monochromatic harmonics for various targets, including Mn, Cr, Sn, and In. We identify most of the ionic/neutral transitions responsible for the enhancement, which all have strong oscillator strengths. We demonstrate intensity enhancements of the 13th, 17th, 29th, and 33rd harmonics from these targets using the 800 nm pump laser and varying its chirp. We also characterized the attosecond nature of such plasma harmonics, measuring attosecond pulse trains with 360 as duration for chromium plasma, using the technique of 'Reconstruction of Attosecond Beating by Interference of Two-photon Transitions'(RABBIT). These results show that plasma harmonics are intense source of ultrashort coherent soft x-rays.

  11. A Highly intense DC muon source, MuSIC and muon CLFV search

    NASA Astrophysics Data System (ADS)

    Hino, Y.; Kuno, Y.; Sato, A.; Sakamoto, H.; Matsumoto, Y.; Tran, N. H.; Hashim, I. H.; Fukuda, M.; Hayashida, Y.; Ogitsu, T.; Yamamoto, A.; Yoshida, M.

    2014-08-01

    MuSIC is a new muon facility, which provides the world's highest intense muon beam with continuous time structure at Research Center of Nuclear Physics (RCNP), Osaka University. It's intensity is designed to be 108 muons per second with only 0.4 kW proton beam. Such a high intense muon beam is very important for searches of rare decay processes, for example search for the muon to electron conversion.

  12. High-order harmonics from bow wave caustics driven by a high-intensity laser

    NASA Astrophysics Data System (ADS)

    Esirkepov, T. Zh.; Pirozhkov, A. S.; Kando, M.; Gallegos, P.; Ahmed, H.; Ragozin, E. N.; Faenov, A. Ya.; Pikuz, T. A.; Kawachi, T.; Sagisaka, A.; Koga, J. K.; Coury, M.; Green, J.; Foster, P.; Brenner, C.; Dromey, B.; Symes, D. R.; Mori, M.; Kawase, K.; Kameshima, T.; Fukuda, Y.; Chen, L. M.; Daito, I.; Ogura, K.; Hayashi, Y.; Kotaki, H.; Kiriyama, H.; Okada, H.; Nishimori, N.; Imazono, T.; Kondo, K.; Kimura, T.; Tajima, T.; Daido, H.; Rajeev, P.; Mckenna, P.; Borghesi, M.; Neely, D.; Kato, Y.; Bulanov, S. V.

    2012-07-01

    We propose a new mechanism of high-order harmonic generation during an interaction of a high-intensity laser pulse with underdense plasma. A tightly focused laser pulse creates a cavity in plasma pushing electrons aside and exciting the wake wave and the bow wave. At the joint of the cavity wall and the bow wave boundary, an annular spike of electron density is formed. This spike surrounds the cavity and moves together with the laser pulse. Collective motion of electrons in the spike driven by the laser field generates high-order harmonics. A strong localization of the electron spike, its robustness to oscillations imposed by the laser field and, consequently, its ability to produce high-order harmonics is explained by catastrophe theory. The proposed mechanism explains the experimental observations of high-order harmonics with the 9 TW J-KAREN laser (JAEA, Japan) and the 120 TW Astra Gemini laser (CLF RAL, UK) [A. S. Pirozhkov, et al., arXiv:1004.4514 (2010); A. S. Pirozhkov et al, AIP Proceedings, this volume]. The theory is corroborated by high-resolution two-and three-dimensional particle-in-cell simulations.

  13. Impact of High-intensity Intermittent and Moderate-intensity Continuous Exercise on Autonomic Modulation in Young Men.

    PubMed

    Cabral-Santos, C; Giacon, T R; Campos, E Z; Gerosa-Neto, J; Rodrigues, B; Vanderlei, L C M; Lira, F S

    2016-06-01

    The aim of this study was to compare heart rate variability (HRV) recovery after two iso-volume (5 km) exercises performed at different intensities. 14 subjects volunteered (25.17±5.08 years; 74.7±6.28 kg; 175±0.05 cm; 59.56±5.15 mL·kg(-1)·min(-1)) and after determination of peak oxygen uptake (VO2Peak) and the speed associated with VO2Peak (sVO2Peak), the subjects completed 2 random experimental trials: high-intensity exercise (HIE - 1:1 at 100% sVO2Peak), and moderate-intensity continuous exercise (MIE - 70% sVO2Peak). HRV and RR intervals were monitored before, during and after the exercise sessions together with, the HRV analysis in the frequency domains (high-frequency - HF: 0.15 to 0.4 Hz and low-frequency - LF: 0.04 to 0.15 Hz components) and the ratio between them (LF/HF). Statistical analysis comparisons between moments and between HIE and MIE were performed using a mixed model. Both exercise sessions modified LFlog, HFlog, and LF/HF (F=16.54, F=19.32 and F=5.17, p<0.05, respectively). A group effect was also found for LFlog (F=23.91, p<0.05), and HFlog (F=57.55, p< 0.05). LF/HF returned to resting value 15 min after MIE exercise and 20 min after HIE exercise. This means that the heavy domain (aerobic and anaerobic threshold) induces dissimilar autonomic modification in physically active subjects. Both HIE and MIE modify HRV, and generally HIE delays parasympathetic autonomic modulation recovery after iso-volume exercise. PMID:26951480

  14. High-intensity drying processes-impulse drying. Yearly report

    SciTech Connect

    Orloff, D.I.

    1991-06-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during the manufacture of paper and similar web products. impulse drying occurs when a wet paper web passes through a press nip in which one of the rolls is heated to a high temperature. A steam layer adjacent to the heated surface grows and displaces water from the sheet in a very efficient manner. The energy required for water removal is very much less than that required for conventional evaporative drying. To eliminate sheet delamination, low thermal mass ceramic press roll coatings were developed to reduce heat transfer to the sheet, while maintaining high heat flux during early stages of the process. In so doing, most of the transferred energy is used to form steam that displaces liquid water, rather than in excessively heating the sheet. During this period, a prototype ceramic coating was developed and its impulse drying performance was compared to that of steel surfaces. It was observed that ceramic platens can be operated at higher temperatures and pressures resulting in improved water removal and physical properties without inducing sheet delamination. Heat flux measurement techniques were developed to provide a mechanistic explanation for the superior performance of the prototype. The work confirmed that the prototype ceramic coating is more energy efficient than the steel surface.

  15. High-intensity drying processes-impulse drying

    SciTech Connect

    Orloff, D.I.

    1991-06-01

    Impulse drying is an innovative process for drying paper that holds great promise for reducing the energy consumed during the manufacture of paper and similar web products. impulse drying occurs when a wet paper web passes through a press nip in which one of the rolls is heated to a high temperature. A steam layer adjacent to the heated surface grows and displaces water from the sheet in a very efficient manner. The energy required for water removal is very much less than that required for conventional evaporative drying. To eliminate sheet delamination, low thermal mass ceramic press roll coatings were developed to reduce heat transfer to the sheet, while maintaining high heat flux during early stages of the process. In so doing, most of the transferred energy is used to form steam that displaces liquid water, rather than in excessively heating the sheet. During this period, a prototype ceramic coating was developed and its impulse drying performance was compared to that of steel surfaces. It was observed that ceramic platens can be operated at higher temperatures and pressures resulting in improved water removal and physical properties without inducing sheet delamination. Heat flux measurement techniques were developed to provide a mechanistic explanation for the superior performance of the prototype. The work confirmed that the prototype ceramic coating is more energy efficient than the steel surface.

  16. Data intensive high energy physics analysis in a distributed cloud

    NASA Astrophysics Data System (ADS)

    Charbonneau, A.; Agarwal, A.; Anderson, M.; Armstrong, P.; Fransham, K.; Gable, I.; Harris, D.; Impey, R.; Leavett-Brown, C.; Paterson, M.; Podaima, W.; Sobie, R. J.; Vliet, M.

    2012-02-01

    We show that distributed Infrastructure-as-a-Service (IaaS) compute clouds can be effectively used for the analysis of high energy physics data. We have designed a distributed cloud system that works with any application using large input data sets requiring a high throughput computing environment. The system uses IaaS-enabled science and commercial clusters in Canada and the United States. We describe the process in which a user prepares an analysis virtual machine (VM) and submits batch jobs to a central scheduler. The system boots the user-specific VM on one of the IaaS clouds, runs the jobs and returns the output to the user. The user application accesses a central database for calibration data during the execution of the application. Similarly, the data is located in a central location and streamed by the running application. The system can easily run one hundred simultaneous jobs in an efficient manner and should scale to many hundreds and possibly thousands of user jobs.

  17. Constant Light Output Ballasting For High Intensity Discharge Lamps

    NASA Astrophysics Data System (ADS)

    Donkin, Adrian

    1988-02-01

    Since the commercial introduction some twenty years ago of HMI* (Hydragyrum-mercury, Medium, Iodide) type lamps, as a source intended primarily for floodlighting applications, their attraction as a cinematographic light source has been apparent due to their largely desirable characteristics. Use in this field has been restricted due to the absolute requirement for an alternating current supply - with a sine wave supply frame rates are limited to a sub-multiple of the supply frequency with the supply frequency phase locked to the camera frame rate. This has effectively barred metal halide HID lighting from use in high speed photography. The general characteristics of metal halide HID lamps are presented alongside a sample of other light sources. An electronic ballast which has been proven to 12000 Watts in the motion picture industry is then described which overcomes the limitations of the conventional magnetic ballast - the square wave output of the electronic ballast theoretically allows the use of any camera frame rate/shutter angle combination. Finally the suitability of luminaires for high speed photography is discussed.

  18. Experimental study of a high intensity radio-frequency cooler

    NASA Astrophysics Data System (ADS)

    Boussaid, Ramzi; Ban, G.; Cam, J. F.

    2015-07-01

    Within the framework of the DESIR/SPIRAL-2 project, a radio-frequency quadrupole cooler named SHIRaC has been studied. SHIRaC is a key device of SPIRAL-2, designed to enhance the beam quality required by DESIR. The preliminary study and development of this device has been carried out at Laboratoire de Physique Corpusculaire de CAEN (LPC Caen), France. The goal of this paper is to present the experimental studies conducted on a SHIRaC prototype. The main peculiarity of this cooler is its efficient handling and cooling of ion beams with currents going up as high as 1 μ A which has never before been achieved in any of the previous coolers. Much effort has been made lately into these studies for development of appropriate optics, vacuum and rf systems which allow cooling of beams of large emittance (˜80 π mm mrad ) and high current. The dependencies of SHIRaC's transmission and the cooled beam parameters in terms of geometrical transverse emittance and the longitudinal energy spread have also been discussed. Investigation of beam purity at optimum cooling condition has also been done. Results from the experiments indicate that an emittance reduction of less than 2.5 π mm mrad and a longitudinal energy spread reduction of less than 4 eV are obtained with more than 70% of ion transmission. The emittance is at expected values whereas the energy spread is not.

  19. The possible ocular hazards of LED dental illumination applications.

    PubMed

    Stamatacos, Catherine; Harrison, Janet L

    2013-01-01

    The use of high-intensity illumination via Light-Emitting Diode (LED) headlamps is gaining in popularity with dentists and student dentists. Practitioners are using LED headlamps together with magnifying loupes, overhead LED illumination and fiber-optic dental handpieces for long periods of time. Although most manufacturers of these LED illuminators advertise that their devices emit "white" light, these still consist of two spectral bands--the blue spectral band, with its peak at 445 nm, and the green with its peak at 555 nm. While manufacturers suggest that their devices emit "white" light, spectral components of LED lights from different companies are significantly different. Dental headlamp manufacturers strive to create a white LED, and they advertise that this type of light emitted from their product offers bright white-light illumination. However, the manufacturing of a white LED light is done through selection of a white LED-type based on the peak blue strength in combination with the green peak strength and thus creating a beam-forming optic, which determines the beam quality. Some LED illuminators have a strong blue-light component versus the green-light component. Blue-light is highly energized and is close in the color spectrum to ultraviolet-light. The hazards of retinal damage with the use of high-intensity blue-lights has been well-documented. There is limited research regarding the possible ocular hazards of usage of high-intensity illuminating LED devices. Furthermore, the authors have found little research, standards, or guidelines examining the possible safety issues regarding the unique dental practice setting consisting of the combined use of LED illumination systems. Another unexamined component is the effect of high-intensity light reflective glare and magnification back to the practitioner's eyes due to the use of water during dental procedures. Based on the result of Dr. Janet Harrison's observations of beginning dental students in a

  20. The possible ocular hazards of LED dental illumination applications.

    PubMed

    Stamatacos, Catherine; Harrison, Janet L

    2014-04-01

    The use of high-intensity illumination via Light-Emitting Diode (LED) headlamps is gaining in popularity with dentists and student dentists. Practitioners are using LED headlamps together with magnifying loupes, overhead LED illumination and fiber-optic dental handpieces for long periods of time. Although most manufacturers of these LED illuminators advertise that their devices emit "white" light, these still consist of two spectral bands - the blue spectral band, with its peak at 445 nm, and the green with its peak at 555 nm. While manufacturers suggest that their devices emit "white" light, spectral components of LED lights from different companies are significantly different. Dental headlamp manufacturers strive to create a white LED, and they advertise that this type of light emitted from their product offers bright white-light illumination. However, the manufacturing of a white LED light is done through selection of a white LED-type based on the peak blue strength in combination with the green peak strength and thus creating a beam-forming optic, which determines the beam quality. Some LED illuminators have a strong blue-light component versus the green-light component. Blue-light is highly energized and is close in the color spectrum to ultraviolet-light. The hazards of retinal damage with the use of high-intensity blue-lights has been well-documented. There is limited research regarding the possible ocular hazards of usage of high-intensity illuminating LED devices. Furthermore, the authors have found little research, standards, or guidelines examining the possible safety issues regarding the unique dental practice setting consisting of the combined use of LED illumination systems. Another unexamined component is the effect of high-intensity light reflective glare and magnification back to the practitioner's eyes due to the use of water during dental procedures. Based on the result of Dr. Janet Harrison's observations of beginning dental students in a

  1. High-intensity xenon pulse light source for fluorescence excitation

    NASA Astrophysics Data System (ADS)

    Miyamoto, Makoto; Ueno, Kazuo

    1997-05-01

    A newly developed 60W xenon flash lamp, L6604 and L6605, achieves the goals of longer operating life, higher output, and improved light stability. It operates at 2 Joules per flash input energy with approximately a 4 microsecond flash duration. The stability achieved is 2-3 percent peak-to-peak during a lifetime of 5 X 10e7 flashes, which is almost double that of conventional xenon flash lamps. This newly developed xenon flashlamp should serve as an excellent light source for analytical cytology and other fluorescence instruments. It can function as a high output, stable excitation light source for conventional fluorescence or delayed luminescence with a CCD. Besides providing powerful and stable illumination for absorption analysis of cells on slides, this lamp eliminates the optical artifacts associated with vibration of the stage which often limit throughput. This paper will describe in detail performance improvements obtained from this newly developed xenon flash lamp.

  2. Tools and techniques for estimating high intensity RF effects

    NASA Technical Reports Server (NTRS)

    Zacharias, Richard L.; Pennock, Steve T.; Poggio, Andrew J.; Ray, Scott L.

    1992-01-01

    Tools and techniques for estimating and measuring coupling and component disturbance for avionics and electronic controls are described. A finite-difference-time-domain (FD-TD) modeling code, TSAR, used to predict coupling is described. This code can quickly generate a mesh model to represent the test object. Some recent applications as well as the advantages and limitations of using such a code are described. Facilities and techniques for making low-power coupling measurements and for making direct injection test measurements of device disturbance are also described. Some scaling laws for coupling and device effects are presented. A method for extrapolating these low-power test results to high-power full-system effects are presented.

  3. Generating long sequences of high-intensity femtosecond pulses.

    PubMed

    Bitter, M; Milner, V

    2016-02-01

    We present an approach to creating pulse sequences extending beyond 150 ps in duration, comprised of 100 μJ femtosecond pulses. A quarter of the pulse train is produced by a high-resolution pulse shaper, which allows full controllability over the timing of each pulse. Two nested Michelson interferometers follow to quadruple the pulse number and the sequence duration. To boost the pulse energy, the long train is sent through a multipass Ti:sapphire amplifier, followed by an external compressor. A periodic sequence of 84 pulses of 120 fs width and an average pulse energy of 107 μJ, separated by 2 ps, is demonstrated as a proof of principle. PMID:26836087

  4. Study of a final focus system for high intensity beams

    SciTech Connect

    Henestroza, Enrique; Eylon, Shmuel; Roy, Prabir K.; Yu, Simon S.; Bieniosek, Frank M.; Shuman, Derek B.; Waldron, William L.

    2004-06-01

    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. The final focus scenario in an HIF driver consists of several large aperture quadrupole magnets followed by a drift section in which the beam space charge is neutralized by a plasma. This beam is required to hit a millimeter-sized target spot at the end of the drift section. The objective of the NTX experiments and associated theory and simulations is to study the various physical mechanisms that determine the final spot size (radius r{sub s}) at a given distance (f) from the end of the last quadrupole. In a fusion driver, f is the standoff distance required to keep the chamber wall and superconducting magnets properly protected. The NTX final quadrupole focusing system produces a converging beam at the entrance to the neutralized drift section where it focuses to a small spot. The final spot is determined by the conditions of the beam entering the quadrupole section, the beam dynamics in the magnetic lattice, and the plasma neutralization dynamics in the drift section. The main issues are the control of emittance growth due to high order fields from magnetic multipoles and image fields. In this paper, we will describe the theoretical and experimental aspects of the beam dynamics in the quadrupole lattice, and how these physical effects influence the final beam size. In particular, we present theoretical and experimental results on the dependence of final spot size on geometric aberrations and perveance.

  5. Is Moderate Intensity Exercise Training Combined with High Intensity Interval Training More Effective at Improving Cardiorespiratory Fitness than Moderate Intensity Exercise Training Alone?

    PubMed Central

    Roxburgh, Brendon H.; Nolan, Paul B.; Weatherwax, Ryan M.; Dalleck, Lance C.

    2014-01-01

    The purpose of this study was to compare the effectiveness of either continuous moderate intensity exercise training (CMIET) alone vs. CMIET combined with a single weekly bout of high intensity interval training (HIIT) on cardiorespiratory fitness. Twenty nine sedentary participants (36.3 ± 6.9 yrs) at moderate risk of cardiovascular disease were recruited for 12 weeks of exercise training on a treadmill and cycle ergometer. Participants were randomised into three groups: CMIET + HIIT (n = 7; 8-12 x 60 sec at 100% VO2max, 150 sec active recovery), CMIET (n = 6; 30 min at 45-60% oxygen consumption reserve (VO2R)) and a sedentary control group (n = 7). Participants in the CMIET + HIIT group performed a single weekly bout of HIIT and four weekly sessions of CMIET, whilst the CMIET group performed five weekly CMIET sessions. Probabilistic magnitude-based inferences were determined to assess the likelihood that the true value of the effect represents substantial change. Relative VO2max increased by 10.1% (benefit possible relative to control) in in the CMIET + HIIT group (32.7 ± 9.2 to 36.0 ± 11.5 mL·kg-1·min-1) and 3.9% (benefit possible relative to control) in the CMIET group (33.2 ± 4.0 to 34.5 ± 6.1 mL·kg-1·min-1), whilst there was a 5.7% decrease in the control group (30.0 ± 4.6 to 28.3 ± 6.5 mL·kg-1·min-1). It was ‘unclear’ if a clinically significant difference existed between the effect of CMIET + HIIT and CMIET on the change in VO2max. Both exercising groups showed clinically meaningful improvements in VO2max. Nevertheless, it remains ‘unclear’ whether one type of exercise training regimen elicits a superior improvement in cardiorespiratory fitness relative to its counterpart. Key Points Both continuous moderate intensity exercise training (CMIET) alone and CMIET combined with a single weekly bout of high intensity interval training (CMIET + HIIT) elicit ‘possibly beneficial’ clinically meaningful improvements in cardiorespiratory

  6. High-Intensity Plasma Glass Melter Final Technical Report

    SciTech Connect

    Gonterman, J. Ronald; Weinstein, Michael A.

    2006-10-27

    frits. Exploratory melts of non-glassy materials, such as wollastonite, zirconium silicate, and alumino-silicate melts were successfully done indicating that plasma melting has potential application beyond glass. Experimental results were generated that show the high quality of plasma-melted fiberglass compositions, such as E-glass, can result in good fiberizing performance. Fiberizing performance and tensile strength data were achieved during the project to support this conclusion. High seed counts are a feature of the current lab scale melter and must be dealt with via other means, since fining work was outside the scope of this project.

  7. New approach to color calibration of high fidelity color digital camera by using unique wide gamut color generator based on LED diodes

    NASA Astrophysics Data System (ADS)

    Kretkowski, M.; Shimodaira, Y.; Jabłoński, R.

    2008-11-01

    Development of a high accuracy color reproduction system requires certain instrumentation and reference for color calibration. Our research led to development of a high fidelity color digital camera with implemented filters that realize the color matching functions. The output signal returns XYZ values which provide absolute description of color. In order to produce XYZ output a mathematical conversion must be applied to CCD output values introducing a conversion matrix. The conversion matrix coefficients are calculated by using a color reference with known XYZ values and corresponding output signals from the CCD sensor under each filter acquisition from a certain amount of color samples. The most important feature of the camera is its ability to acquire colors from the complete theoretically visible color gamut due to implemented filters. However market available color references such as various color checkers are enclosed within HDTV gamut, which is insufficient for calibration in the whole operating color range. This led to development of a unique color reference based on LED diodes called the LED Color Generator (LED CG). It is capable of displaying colors in a wide color gamut estimated by chromaticity coordinates of 12 primary colors. The total amount of colors possible to produce is 25512. The biggest advantage is a possibility of displaying colors with desired spectral distribution (with certain approximations) due to multiple primary colors it consists. The average color difference obtained for test colors was found to be ▵E~0.78 for calibration with LED CG. The result is much better and repetitive in comparison with the Macbeth ColorCheckerTM which typically gives ▵E~1.2 and in the best case ▵E~0.83 with specially developed techniques.

  8. Improvement of high-voltage staircase drive circuit waveform for high-intensity therapeutic ultrasound

    NASA Astrophysics Data System (ADS)

    Tamano, Satoshi; Jimbo, Hayato; Azuma, Takashi; Yoshizawa, Shin; Fujiwara, Keisuke; Itani, Kazunori; Umemura, Shin-Ichiro

    2016-07-01

    Recently, in the treatment of diseases such as cancer, noninvasive or low-invasive modality, such as high-intensity focused ultrasound (HIFU), has been put into practice as an alternative to open surgery. HIFU induces thermal ablation of the target tissue to be treated. To improve the efficiency of HIFU, we have proposed a “triggered-HIFU” technique, which uses the combination of a short-duration, high-voltage transmission and a long-duration, medium-voltage transmission. In this method, the transmission device must endure high peak voltage for the former and the high time-average power for the latter. The triggered-HIFU sequence requires electronic scanning of the HIFU focus to maximize its thermal efficiency. Therefore, the transmission device must drive an array transducer with the number of elements on the order of a hundred or more, which requires that each part of the device that drives each element must be compact. The purpose of this work is to propose and construct such a transmission device by improving the staircase drive circuit, which we previously proposed. The main point of improvement is that both N and P MOSFETs are provided for each staircase voltage level instead of only one of them. Compared with the previous ultrasonic transmission circuit, high-voltage spikes were significantly reduced, the power consumption was decreased by 26.7%, and the transmission circuit temperature rise was decreased by 14.5 °C in the triggered-HIFU heating mode.

  9. High Energy K(alpha) Radiography Using High-intensity, Short-pulse Lasers

    SciTech Connect

    Park, H; Izumi, N; Key, M H; King, J A; Koch, J A; Landen, O L; Patel, P K; Price, D F; Remington, B A; Robey, H F; Snavely, R A; Tabak, M; Town, R J; Wickersham, J E; Stoeckl, C; Storm, M; Theobald, W; Chambers, D M; Eagelton, R; Goldsack, T; Clarke, R J; Heathcote, R; Giraldez, E; Nikroo, A; Steinman, D A; Stephens, R B; Zhang, B B

    2005-11-16

    We have performed experiments using Callisto, the Vulcan 100 TW and the Vulcan Petawatt high intensity lasers to understand the characteristics of high energy, K{alpha} x-ray sources and to implement workable radiography solutions at 20-100 keV. Our measurements show that the K{alpha} size from a simple foil target is larger than 60 {micro}m, far larger than the experiment resolution requirement. The total K{alpha} yield is independent of target thicknesses verifying that refluxing plays a major role in photon generation. Smaller radiating volumes emit brighter K{alpha} radiation. 1-D radiography experiments using small-edge-on foils resolved 10 {micro}m features with high contrast. We tested a variety of small volume 2-D point sources such as cones, wires, and embedded wires, measuring photon yields and comparing our measurements with predictions from hybrid-PIC LSP simulations. In addition to high-energy, high-resolution backlighters, future experiments will also need imaging detectors and diagnostic tools that are workable in the 20-100 keV energy range. An initial look at some of these detector issues is also presented.

  10. Retinal damage induced by commercial light emitting diodes (LEDs).

    PubMed

    Jaadane, Imene; Boulenguez, Pierre; Chahory, Sabine; Carré, Samuel; Savoldelli, Michèle; Jonet, Laurent; Behar-Cohen, Francine; Martinsons, Christophe; Torriglia, Alicia

    2015-07-01

    Spectra of "white LEDs" are characterized by an intense emission in the blue region of the visible spectrum, absent in daylight spectra. This blue component and the high intensity of emission are the main sources of concern about the health risks of LEDs with respect to their toxicity to the eye and the retina. The aim of our study was to elucidate the role of blue light from LEDs in retinal damage. Commercially available white LEDs and four different blue LEDs (507, 473, 467, and 449nm) were used for exposure experiments on Wistar rats. Immunohistochemical stain, transmission electron microscopy, and Western blot were used to exam the retinas. We evaluated LED-induced retinal cell damage by studying oxidative stress, stress response pathways, and the identification of cell death pathways. LED light caused a state of suffering of the retina with oxidative damage and retinal injury. We observed a loss of photoreceptors and the activation of caspase-independent apoptosis, necroptosis, and necrosis. A wavelength dependence of the effects was observed. Phototoxicity of LEDs on the retina is characterized by a strong damage of photoreceptors and by the induction of necrosis. PMID:25863264

  11. Diffraction Gratings for High-Intensity Laser Applications

    SciTech Connect

    Britten, J

    2008-01-23

    The scattering of light into wavelength-dependent discrete directions (orders) by a device exhibiting a periodic modulation of a physical attribute on a spatial scale similar to the wavelength of light has been the subject of study for over 200 years. Such a device is called a diffraction grating. Practical applications of diffraction gratings, mainly for spectroscopy, have been around for over 100 years. The importance of diffraction gratings in spectroscopy for the measurement of myriad properties of matter can hardly be overestimated. Since the advent of coherent light sources (lasers) in the 1960's, applications of diffraction gratings in spectroscopy have further exploded. Lasers have opened a vast application space for gratings, and apace, gratings have enabled entirely new classes of laser systems. Excellent reviews of the history, fundamental properties, applications and manufacturing techniques of diffraction gratings up to the time of their publication can be found in the books by Hutley (1) and more recently Loewen and Popov (2). The limited scope of this chapter can hardly do justice to such a comprehensive subject, so the focus here will be narrowly limited to characteristics required for gratings suitable for high-power laser applications, and methods to fabricate them. A particular area of emphasis will be on maximally-efficient large-aperture gratings for short-pulse laser generation.

  12. Computational aspects in high intensity ultrasonic surgery planning.

    PubMed

    Pulkkinen, A; Hynynen, K

    2010-01-01

    Therapeutic ultrasound treatment planning is discussed and computational aspects regarding it are reviewed. Nonlinear ultrasound simulations were solved with a combined frequency domain Rayleigh and KZK model. Ultrasonic simulations were combined with thermal simulations and were used to compute heating of muscle tissue in vivo for four different focused ultrasound transducers. The simulations were compared with measurements and good agreement was found for large F-number transducers. However, at F# 1.9 the simulated rate of temperature rise was approximately a factor of 2 higher than the measured ones. The power levels used with the F# 1 transducer were too low to show any nonlinearity. The simulations were used to investigate the importance of nonlinarities generated in the coupling water, and also the importance of including skin in the simulations. Ignoring either of these in the model would lead to larger errors. Most notably, the nonlinearities generated in the water can enhance the focal temperature by more than 100%. The simulations also demonstrated that pulsed high power sonications may provide an opportunity to significantly (up to a factor of 3) reduce the treatment time. In conclusion, nonlinear propagation can play an important role in shaping the energy distribution during a focused ultrasound treatment and it should not be ignored in planning. However, the current simulation methods are accurate only with relatively large F-numbers and better models need to be developed for sharply focused transducers. PMID:19740625

  13. The high intensity solar cell: Key to low cost photovoltaic power

    NASA Technical Reports Server (NTRS)

    Sater, B. L.; Goradia, C.

    1975-01-01

    The design considerations and performance characteristics of the 'high intensity' (HI) solar cell are presented. A high intensity solar system was analyzed to determine its cost effectiveness and to assess the benefits of further improving HI cell efficiency. It is shown that residential sized systems can be produced at less than $1000/kW peak electric power. Due to their superior high intensity performance characteristics compared to the conventional and VMJ cells, HI cells and light concentrators may be the key to low cost photovoltaic power.

  14. A 3 Ghz photoelectron gun for high beam intensity

    SciTech Connect

    Bossart, R.; Braun, H.; Dehler, M.

    1995-12-31

    The CLIC Test Facility (CTF) for new accelerator structures of the proposed Compact Linear Collider (CLIC) is to be equipped with a new RF gun containing a laser driven photocathode. The new 3 GHz gun with photocathode shall produce a bunch train of 48 electron bunches of 25 nC charge each with a bunch length of 8 - 15 ps fwhm. The new RF gun consists of 2{1/2} cells and accelerates the beam to an energy of 7 MeV with a peak field gradient Ez = 100 MV/m. The strong space charge forces at low beam energy caused by the high charge density of the electron bunches must be contained by radial and longitudinal RF focusing in the RF gun. Radial RF focusing is applied by a conical backplane around the photocathode in the first cell where the electrons have a low energy. Longitudinal RF focusing is obtained by varying the length of each of the three cells of the gun. The total electric charge of the bunch train exceeds 1{mu}C and causes strong beam loading to the RF structures so that the stored energy is reduced to half of the unloaded RF energy. The RF gun under construction is being optimized by MAFIA beam simulations for an injector assembly comprising a second accelerating RF structure of 4 cells and an intermediate solenoid magnet correcting the beam divergence of the 2{1/2} cell gun. The scheme with two accelerating RF sections will provide a linear energy increase along the bunch suitable for further compression of the bunch length in a magnetic chicane.

  15. High-intensity, high-brightness polarized and unpolarized beam production in charge-exchange collisions

    SciTech Connect

    Zelenski, A.; Ritter, J.; Zubets, V.; Steski, D.; Atoian, G.; Davydenko, V.; Ivanov, A.; Kolmogorov, A.

    2011-03-28

    Basic limitations on the high-intensity H{sup -} ion beam production were experimentally studied in charge-exchange collisions of the neutral atomic hydrogen beam in the Na-vapour jet ionizer cell. These studies are the part of the polarized source upgrade (to 10 mA peak current and 85% polarization) project for RHIC. In the source the atomic hydrogen beam of a 5-10 keV energy and total (equivalent) current up to 5 A is produced by neutralization of proton beam in pulsed hydrogen gas target. Formation of the proton beam (from the surface of the plasma emitter with a low transverse ion temperature {approx}0.2 eV) is produced by four-electrode spherical multi-aperture ion-optical system with geometrical focusing. The hydrogen atomic beam intensity up to 1.0 A/cm{sup 2} (equivalent) was obtained in the Na-jet ionizer aperture of a 2.0 cm diameter. At the first stage of the experiment H-beam with 36 mA current, 5 keV energy and {approx}1.0 cm {center_dot} mrad normalized emittance was obtained using the flat grids and magnetic focusing.

  16. Conceptual design of a high-intensity positron source for the Advanced Neutron Source

    SciTech Connect

    Hulett, L.D.; Eberle, C.C.

    1994-12-01

    The Advanced Neutron Source (ANS) is a planned new basic and applied research facility based on a powerful steady-state research reactor that provides neutrons for measurements and experiments in the fields of materials science and engineering, biology, chemistry, materials analysis, and nuclear science. The useful neutron flux will be at least five times more than is available in the world`s best existing reactor facility. Construction of the ANS provides a unique opportunity to build a positron spectroscopy facility (PSF) with very-high-intensity beams based on the radioactive decay of a positron-generating isotope. The estimated maximum beam current is 1000 to 5000 times higher than that available at the world`s best existing positron research facility. Such an improvement in beam capability, coupled with complementary detectors, will reduce experiment durations from months to less than one hour while simultaneously improving output resolution. This facility will remove the existing barriers to the routine use of positron-based analytical techniques and will be a giant step toward realization of the full potential of the application of positron spectroscopy to materials science. The ANS PSF is based on a batch cycle process using {sup 64}Cu isotope as the positron emitter and represents the status of the design at the end of last year. Recent work not included in this report, has led to a proposal for placing the laboratory space for the positron experiments outside the ANS containment; however, the design of the positron source is not changed by that relocation. Hydraulic and pneumatic flight tubes transport the source material between the reactor and the positron source where the beam is generated and conditioned. The beam is then transported through a beam pipe to one of several available detectors. The design presented here includes all systems necessary to support the positron source, but the beam pipe and detectors have not been addressed yet.

  17. End-face preparation methods for high-intensity fiber applications

    SciTech Connect

    Setchell, R.E.

    1997-10-01

    High laser intensities are being transmitted through optical fibers in a growing number of applications. The author`s interest in laser initiation of explosives has led him to examine the transmission of Q-switched, Nd:YAG laser pulses through step-index, multimode, fused-silica fibers for a number of years. A common limiting process is a plasma-forming breakdown occurring at the fiber entrance face. The breakdown threshold at this face depends on the surface characteristics that result from the particular method of end-face preparation. In previous studies he examined entrance-face breakdown thresholds for several different mechanical polishing schedules, and also for several schedules of CO{sub 2}-laser conditioning following mechanical polishing. In the present study he examined three end-face preparation methods that were based on the recent availability of exceptionally good cleaved surfaces for the fibers of interest. Using test procedures similar to those in past studies, he examined the cleaved fibers directly, fibers with cleaved surfaces that were subsequently flame polished, and fibers with cleaved surfaces that were subsequently conditioned with a CO{sub 2} laser. All of these preparation methods resulted in fibers that showed a broader range of entrance-face breakdown conditions than found in past studies, together with a susceptibility to subsurface exit-face damage. By introducing additional cleaning steps with the cleaved surfaces, he was able to reduce the variability in breakdown thresholds observed after subsequent CO{sub 2}-laser conditioning. A consistent location of exit-face damage sites indicates that subsurface fracturing occurs during the cleaving process, and that the subsequent end-face processing steps were not effective in mitigating damage at these sites. Threshold energies for entrance-face breakdown are also affected by the relation between incident laser energy and the resulting peak local fluence at this surface.

  18. Lymphocyte Redox Imbalance and Reduced Proliferation after a Single Session of High Intensity Interval Exercise

    PubMed Central

    Tossige-Gomes, Rosalina; Costa, Karine Beatriz; Ottone, Vinícius de Oliveira; Magalhães, Flávio de Castro; Amorim, Fabiano Trigueiro; Rocha-Vieira, Etel

    2016-01-01

    This study investigated whether an acute session of high-intensity interval training (HIIT) is sufficient to alter lymphocyte function and redox status. Sixteen young healthy men underwent a HIIT session on a cycloergometer, consisting of eight bouts of 1 min at 90–100% of peak power, with 75 seconds of active recovery at 30 W between bouts. Venous blood was collected before, immediately after, and 30 minutes after the HIIT session. In response to Staphylococcus aureus superantigen B (SEB) stimulation, lymphocyte proliferation decreased and the IL-2 concentration increased after the HIIT session. However, the HIIT session had no effect on lymphocyte proliferation or IL-2 response to phytohemagglutinin stimulation. The HIIT session also induced lymphocyte redox imbalance, characterized by an increase in the concentration of thiobarbituric acid reactive substances and a decrease in the activity of the antioxidant enzyme catalase. Lymphocyte viability was not affected by the HIIT session. The frequencies of CD25+ and CD69+ T helper and B lymphocytes in response to superantigen stimulation were lower after exercise, suggesting that superantigen-induced lymphocyte activation was reduced by HIIT. However, HIIT also led to a reduction in the frequency of CD4+ and CD19+ cells, so the frequencies of CD25+ and CD69+ cells within the CD4 and CD19 cell populations were not affected by HIIT. These data indicate that the reduced lymphocyte proliferation observed after HIIT is not due to reduced early lymphocyte activation by superantigen. Our findings show that an acute HIIT session promotes lymphocyte redox imbalance and reduces lymphocyte proliferation in response to superantigenic, but not to mitogenic stimulation. This observation cannot be explained by alteration of the early lymphocyte activation response to superantigen. The manner in which lymphocyte function modulation by an acute HIIT session can affect individual immunity and susceptibility to infection is important

  19. Lymphocyte Redox Imbalance and Reduced Proliferation after a Single Session of High Intensity Interval Exercise.

    PubMed

    Tossige-Gomes, Rosalina; Costa, Karine Beatriz; Ottone, Vinícius de Oliveira; Magalhães, Flávio de Castro; Amorim, Fabiano Trigueiro; Rocha-Vieira, Etel

    2016-01-01

    This study investigated whether an acute session of high-intensity interval training (HIIT) is sufficient to alter lymphocyte function and redox status. Sixteen young healthy men underwent a HIIT session on a cycloergometer, consisting of eight bouts of 1 min at 90-100% of peak power, with 75 seconds of active recovery at 30 W between bouts. Venous blood was collected before, immediately after, and 30 minutes after the HIIT session. In response to Staphylococcus aureus superantigen B (SEB) stimulation, lymphocyte proliferation decreased and the IL-2 concentration increased after the HIIT session. However, the HIIT session had no effect on lymphocyte proliferation or IL-2 response to phytohemagglutinin stimulation. The HIIT session also induced lymphocyte redox imbalance, characterized by an increase in the concentration of thiobarbituric acid reactive substances and a decrease in the activity of the antioxidant enzyme catalase. Lymphocyte viability was not affected by the HIIT session. The frequencies of CD25+ and CD69+ T helper and B lymphocytes in response to superantigen stimulation were lower after exercise, suggesting that superantigen-induced lymphocyte activation was reduced by HIIT. However, HIIT also led to a reduction in the frequency of CD4+ and CD19+ cells, so the frequencies of CD25+ and CD69+ cells within the CD4 and CD19 cell populations were not affected by HIIT. These data indicate that the reduced lymphocyte proliferation observed after HIIT is not due to reduced early lymphocyte activation by superantigen. Our findings show that an acute HIIT session promotes lymphocyte redox imbalance and reduces lymphocyte proliferation in response to superantigenic, but not to mitogenic stimulation. This observation cannot be explained by alteration of the early lymphocyte activation response to superantigen. The manner in which lymphocyte function modulation by an acute HIIT session can affect individual immunity and susceptibility to infection is important

  20. Research activities on high-intensity laser and high field physics at APRI-GIST

    NASA Astrophysics Data System (ADS)

    Jeong, Tae Moon

    2015-05-01

    The performance of a 0.1-Hz-repetition-rate, 30-fs, 1.5-PW Ti:sapphire laser which is using for research on high field physics in APRI-GIST is presented. The charged particles (electrons and protons) are accelerated and an efficient x-ray generation is demonstrated using the PW laser. Protons are accelerated up to 80 MeV when an ultra-thin polymer target is irradiated by a circularly-polarized PW laser pulse. Electrons are accelerated to multi-GeV level with a help of injector and accelerator scheme. In the relativistic harmonic generation experiment, the harmonic order is dramatically extended, by optimizing the intensity of pre-pulse level, up to 164th that corresponds to 4.9 nm in wavelength and the experimental results can be explained by the oscillatory flying mirror model. The upgrade of the PW laser to the multi-PW level is under way.

  1. Improved highly accurate localized motion imaging for monitoring high-intensity focused ultrasound therapy

    NASA Astrophysics Data System (ADS)

    Qu, Xiaolei; Azuma, Takashi; Sugiyama, Ryusuke; Kanazawa, Kengo; Seki, Mika; Sasaki, Akira; Takeuchi, Hideki; Fujiwara, Keisuke; Itani, Kazunori; Tamano, Satoshi; Takagi, Shu; Sakuma, Ichiro; Matsumoto, Yoichiro

    2016-07-01

    Visualizing an area subjected to high-intensity focused ultrasound (HIFU) therapy is necessary for controlling the amount of HIFU exposure. One of the promising monitoring methods is localized motion imaging (LMI), which estimates coagulation length by detecting the change in stiffness. In this study, we improved the accuracy of our previous LMI by dynamic cross-correlation window (DCCW) and maximum vibration amount (MVA) methods. The DCCW method was used to increase the accuracy of estimating vibration amplitude, and the MVA method was employed to increase signal–noise ratio of the decrease ratio at the coagulated area. The qualitative comparison of results indicated that the two proposed methods could suppress the effect of noise. Regarding the results of the quantitative comparison, coagulation length was estimated with higher accuracy by the improved LMI method, and the root-mean-square error (RMSE) was reduced from 2.51 to 1.69 mm.

  2. Comparison of different LED Packages

    NASA Astrophysics Data System (ADS)

    Dieker, Henning; Miesner, Christian; Püttjer, Dirk; Bachl, Bernhard

    2007-09-01

    In this paper different technologies for LED packaging are compared, focusing on Chip on Board (COB) and SMD technology. The package technology which is used depends on the LED application. A critical fact in LED technology is the thermal management, especially for high brightness LED applications because the thermal management is important for reliability, lifetime and electrooptical performance of the LED module. To design certain and long life LED applications knowledge of the heat flow from LEDs to the complete application is required. High sophisticated FEM simulations are indispensable for modern development of high power LED applications. We compare simulations of various substrate materials and packaging technologies simulated using FLOTHERM software. Thereby different substrates such as standard FR4, ceramic and metal core printed circuit boards are considered. For the verification of the simulated results and the testing of manufactured modules, advanced measurement tools are required. We show different ways to experimentally characterize the thermal behavior of LED modules. The thermal path is determined by the transient thermal analysis using the MicReD T3Ster analyzer. Afterwards it will be compared to the conventional method using thermocouples. The heat distribution over the module is investigated by an IR-Camera. We demonstrate and compare simulation and measurement results of Chip-on-Board (COB) and Sub-Mounted Devices (SMD) technology. The results reveal that for different applications certain packages are ideal.

  3. Design of high power LED-based UVA emission system and a photosensitive substance for clinical application in corneal radiation

    NASA Astrophysics Data System (ADS)

    Mota, Alessandro D.; Cestari, André M.; de Oliveira, André O.; Oliveira, Anselmo G.; Terruggi, Cristina H. B.; Rossi, Giuliano; Castro, Jarbas C.; Ligabô, João. P. B.; Ortega, Tiago A.; Rosa, Tiago

    2015-09-01

    This work presents an innovative cross-linking procedure to keratoconus treatment, a corneal disease. It includes the development of an ultraviolet controlled emission portable device based on LED source and a new formulation of a photosensitive drug called riboflavin. Thus new formulation improves drug administration by its transepithelial property. The UV reaction with riboflavin in corneal tissue leads to a modification of corneal collagen fibers, turning them more rigid and dense, and consequently restraining the advance of the disease. We present the control procedures to maintain UV output power stable up to 45mw/cm2, the optical architecture that leads to a homogeneous UV spot and the new formulation of Riboflavin.

  4. High-Intensity Interval Training as an Efficacious Alternative to Moderate-Intensity Continuous Training for Adults with Prediabetes

    PubMed Central

    Jung, Mary E.; Bourne, Jessica E.; Beauchamp, Mark R.; Robinson, Emily; Little, Jonathan P.

    2015-01-01

    Aims. High-intensity interval training (HIIT) leads to improvements in various markers of cardiometabolic health but adherence to HIIT following a supervised laboratory intervention has yet to be tested. We compared self-report and objective measures of physical activity after one month of independent exercise in individuals with prediabetes who were randomized to HIIT (n = 15) or traditional moderate-intensity continuous training (MICT, n = 17). Method. After completing 10 sessions of supervised training participants were asked to perform HIIT or MICT three times per week for four weeks. Results. Individuals in HIIT (89 ± 11%) adhered to their prescribed protocol to a greater extent than individuals in MICT (71 ± 31%) as determined by training logs completed over one-month follow-up (P = 0.05, Cohen's d = 0.75). Minutes spent in vigorous physical activity per week measured by accelerometer were higher in HIIT (24 ± 18) as compared to MICT (11 ± 10) at one-month follow-up (P = 0.049, Cohen's d = 0.92). Cardiorespiratory fitness and systolic blood pressure assessed at one-month follow-up were equally improved (P's < 0.05). Conclusions. This study provides preliminary evidence that individuals with prediabetes can adhere to HIIT over the short-term and do so at a level that is greater than MICT. PMID:25918728

  5. Intensive lifestyle intervention including high-intensity interval training program improves insulin resistance and fasting plasma glucose in obese patients☆

    PubMed Central

    Marquis-Gravel, Guillaume; Hayami, Douglas; Juneau, Martin; Nigam, Anil; Guilbeault, Valérie; Latour, Élise; Gayda, Mathieu

    2015-01-01

    Objectives To analyze the effects of a long-term intensive lifestyle intervention including high-intensity interval training (HIIT) and Mediterranean diet (MedD) counseling on glycemic control parameters, insulin resistance and β-cell function in obese subjects. Methods The glycemic control parameters (fasting plasma glucose, glycated hemoglobin), insulin resistance, and β-cell function of 72 obese subjects (54 women; mean age = 53 ± 9 years) were assessed at baseline and upon completion of a 9-month intensive lifestyle intervention program conducted at the cardiovascular prevention and rehabilitation center of the Montreal Heart Institute, from 2009 to 2012. The program included 2–3 weekly supervised exercise training sessions (HIIT and resistance exercise), combined to MedD counseling. Results Fasting plasma glucose (FPG) (mmol/L) (before: 5.5 ± 0.9; after: 5.2 ± 0.6; P < 0.0001), fasting insulin (pmol/L) (before: 98 ± 57; after: 82 ± 43; P = 0.003), and insulin resistance, as assessed by the HOMA-IR score (before: 3.6 ± 2.5; after: 2.8 ± 1.6; P = 0.0008) significantly improved, but not HbA1c (%) (before: 5.72 ± 0.55; after: 5.69 ± 0.39; P = 0.448), nor β-cell function (HOMA-β, %) (before: 149 ± 78; after: 144 ± 75; P = 0.58). Conclusion Following a 9-month intensive lifestyle intervention combining HIIT and MedD counseling, obese subjects experienced significant improvements of FPG and insulin resistance. This is the first study to expose the effects of a long-term program combining HIIT and MedD on glycemic control parameters among obese subjects. PMID:26844086

  6. LOW-COST LED LUMINAIRE FOR GENERAL ILLUMINATION

    SciTech Connect

    Lowes, Ted

    2014-07-31

    During this two-year Solid-State Lighting (SSL) Manufacturing R&D project Cree developed novel light emitting diode (LED) technologies contributing to a cost-optimized, efficient LED troffer luminaire platform emitting at ~3500K correlated color temperature (CCT) at a color rendering index (CRI) of >90. To successfully achieve program goals, Cree used a comprehensive approach to address cost reduction of the various optical, thermal and electrical subsystems in the luminaire without impacting performance. These developments built on Cree’s high- brightness, low-cost LED platforms to design a novel LED component architecture that will enable low-cost troffer luminaire designs with high total system efficacy. The project scope included cost reductions to nearly all major troffer subsystems as well as assembly costs. For example, no thermal management components were included in the troffer, owing to the optimized distribution of compact low- to mid-power LEDs. It is estimated that a significant manufacturing cost savings will result relative to Cree’s conventional troffers at the start of the project. A chief project accomplishment was the successful development of a new compact, high-efficacy LED component geometry with a broad far-field intensity distribution and even color point vs. emission angle. After further optimization and testing for production, the Cree XQ series of LEDs resulted. XQ LEDs are currently utilized in Cree’s AR series troffers, and they are being considered for use in other platforms. The XQ lens geometry influenced the independent development of Cree’s XB-E and XB-G high-voltage LEDs, which also have a broad intensity distribution at high efficacy, and are finding wide implementation in Cree’s omnidirectional A-lamps.

  7. High-Intensity Intermittent Exercise: Effect on Young People's Cardiometabolic Health and Cognition.

    PubMed

    Cooper, Simon B; Dring, Karah J; Nevill, Mary E

    2016-01-01

    With only a quarter of young people currently meeting physical activity guidelines, two key areas of concern are the effects of exercise on cardiometabolic health and cognition. Despite the fact that physical activity in young people is typically high intensity and intermittent in nature, much of the literature examines traditional endurance-type exercise. This review provides an update on the effects of high-intensity intermittent exercise on young people's cardiometabolic health and cognition. High-intensity intermittent exercise has acute beneficial effects on endothelial function and postprandial lipemia and chronic positive effects on weight management. In addition, there is emerging evidence regarding chronic benefits on the blood lipid profile, blood pressure, and proinflammatory and anti-inflammatory cytokines. Furthermore, emerging evidence suggests beneficial acute and chronic effects of high-intensity intermittent exercise on cognition. However, further research is required in both cardiometabolic health and cognition, particularly regarding the impact of school-based interventions in adolescents. PMID:27399821

  8. Photocathode fatigue of L-24 PM head due to high intensity light pulses

    SciTech Connect

    Bailey, K.F.

    1980-01-08

    The sensitivity of radiation detectors which utilizes photomultipliers was determined after exposing the multiplier phototubes to high intensity light pulses. Test results found that generally less than a 5% change was found. (FS)

  9. Transcranial MR-guided High Intensity Focused Ultrasound for Non-Invasive Functional Neurosurgery

    NASA Astrophysics Data System (ADS)

    Werner, Beat; Morel, Anne; Zadicario, Eyal; Jeanmonod, Daniel; Martin, Ernst

    2010-03-01

    While the development of transcranial MR-guided High Intensity Focused Ultrasound has been driven mainly by applications for tumor ablation this new intervention method is also very attractive for functional neurosurgery due to its non-invasiveness, the absence of ionizing radiation and the closed-loop intervention control by MRI. Here we provide preliminary data to demonstrate the clinical feasibility, safety and precision of non-invasive functional neurosurgery by transcranial MR-guided High Intensity Focused Ultrasound.

  10. Narrowing of the emission angle in high-intensity Compton scattering

    NASA Astrophysics Data System (ADS)

    Harvey, C. N.; Gonoskov, A.; Marklund, M.; Wallin, E.

    2016-02-01

    We consider the emission spectrum of high-energy electrons in an intense laser field. At high intensities (a0˜200 ) we find that the QED theory predicts a narrower angular spread of emissions than the classical theory. This is due to the classical theory overestimating the energy loss of the particles, resulting in them becoming more susceptible to reflection in the laser pulse.

  11. High Intensity Laser Therapy (HILT) versus TENS and NSAIDs in low back pain: clinical study

    NASA Astrophysics Data System (ADS)

    Zati, Allesandro; Fortuna, Damiano; Valent, A.; Filippi, M. V.; Bilotta, Teresa W.

    2004-09-01

    Low back pain, caused by lumbar disc herniation, is prevalently treated with a conservative approach. In this study we valued the efficacy of High Intensity Laser Therapy (HILT), compared with accepted therapies such as TENS and NSAIDs. Laser therapy obtained similar results in the short term, but better clinical effect over time than TENS and NSAIDs. In conclusion high intensity laser therapy appears to be a interesting new treatment, worthy of further research.

  12. Pubic Bone Osteomyelitis after Salvage High-Intensity Focused Ultrasound for Prostate Cancer

    PubMed Central

    Robison, Christopher M.; Gor, Ronak A.; Metro, Michael J.

    2014-01-01

    High-intensity focused ultrasound can be used for the primary treatment of prostate cancer and biochemical recurrence after radical prostatectomy or radiation. Complications of high-intensity focused ultrasound include urinary retention, urethral stenosis, stress incontinence, urinary tract infections, dysuria, impotence, and rarely, rectourethral or rectovesicular fistula. We describe a patient presenting with urinary retention, urinary tract infections and intermittent stress incontinence, later found to be associated with pubic bone osteomyelitis stemming from a prostatopubic fistula. PMID:24917777

  13. How broadband speech may avoid neural firing rate saturation at high intensities and maintain intelligibility

    PubMed Central

    Bashford, James A.; Warren, Richard M.; Lenz, Peter W.

    2015-01-01

    Three experiments examined the intelligibility enhancement produced when noise bands flank high intensity rectangular band speech. When white noise flankers were added to the speech individually at a low spectrum level (−30 dB relative to the speech) only the higher frequency flanker produced a significant intelligibility increase (i.e., recovery from intelligibility rollover). However, the lower-frequency flanking noise did produce an equivalent intelligibility increase when its spectrum level was increased by 10 dB. This asymmetrical intensity requirement, and other results, support previous suggestions that intelligibility loss at high intensities is reduced by lateral inhibition in the cochlear nuclei. PMID:25920887

  14. Short-term high-intensity interval and moderate-intensity continuous training reduce leukocyte TLR4 in inactive adults at elevated risk of type 2 diabetes.

    PubMed

    Robinson, Emily; Durrer, Cody; Simtchouk, Svetlana; Jung, Mary E; Bourne, Jessica E; Voth, Elizabeth; Little, Jonathan P

    2015-09-01

    Exercise can have anti-inflammatory effects in obesity, but the optimal type and intensity of exercise are not clear. This study compared short-term high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) in terms of improvement in cardiorespiratory fitness, markers of inflammation, and glucose control in previously inactive adults at elevated risk of developing type 2 diabetes. Thirty-nine inactive, overweight/obese adults (32 women) were randomly assigned to 10 sessions over 2 wk of progressive HIIT (n = 20, four to ten 1-min sessions at ∼90% peak heart rate, 1-min rest periods) or MICT (n = 19, 20-50 min at ∼65% peak heart rate). Before and 3 days after training, participants performed a peak O2 uptake test, and fasting blood samples were obtained. Both HIIT (1.8 ± 0.4 vs. 1.9 ± 0.4 l/min, pre vs. post) and MICT (1.8 ± 0.5 vs. 1.9 ± 0.5 l/min, pre vs. post) improved peak O2 uptake (P < 0.001) and lowered plasma fructosamine (P < 0.05). Toll-like receptor (TLR) 4 (TLR4) expression was reduced on lymphocytes and monocytes after both HIIT and MICT (P < 0.05) and on neutrophils after MICT (P < 0.01). TLR2 on lymphocytes was reduced after HIIT and MICT (P < 0.05). Plasma inflammatory cytokines were unchanged after training in both groups, but MICT led to a reduction in fasting plasma glucose (P < 0.05, 5.9 ± 1.0 vs. 5.6 ± 1.0 mmol/l, pre vs. post). Ten days of either HIIT or MICT can improve cardiorespiratory fitness and glucose control and lead to reductions in TLR2 and TLR4 expression. MICT, which involved a longer duration of exercise, may be superior for reducing fasting glucose. PMID:26139217

  15. Short-term high-intensity interval and moderate-intensity continuous training reduce leukocyte TLR4 in inactive adults at elevated risk of type 2 diabetes

    PubMed Central

    Robinson, Emily; Durrer, Cody; Simtchouk, Svetlana; Jung, Mary E.; Bourne, Jessica E.; Voth, Elizabeth

    2015-01-01

    Exercise can have anti-inflammatory effects in obesity, but the optimal type and intensity of exercise are not clear. This study compared short-term high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) in terms of improvement in cardiorespiratory fitness, markers of inflammation, and glucose control in previously inactive adults at elevated risk of developing type 2 diabetes. Thirty-nine inactive, overweight/obese adults (32 women) were randomly assigned to 10 sessions over 2 wk of progressive HIIT (n = 20, four to ten 1-min sessions at ∼90% peak heart rate, 1-min rest periods) or MICT (n = 19, 20-50 min at ∼65% peak heart rate). Before and 3 days after training, participants performed a peak O2 uptake test, and fasting blood samples were obtained. Both HIIT (1.8 ± 0.4 vs. 1.9 ± 0.4 l/min, pre vs. post) and MICT (1.8 ± 0.5 vs. 1.9 ± 0.5 l/min, pre vs. post) improved peak O2 uptake (P < 0.001) and lowered plasma fructosamine (P < 0.05). Toll-like receptor (TLR) 4 (TLR4) expression was reduced on lymphocytes and monocytes after both HIIT and MICT (P < 0.05) and on neutrophils after MICT (P < 0.01). TLR2 on lymphocytes was reduced after HIIT and MICT (P < 0.05). Plasma inflammatory cytokines were unchanged after training in both groups, but MICT led to a reduction in fasting plasma glucose (P < 0.05, 5.9 ± 1.0 vs. 5.6 ± 1.0 mmol/l, pre vs. post). Ten days of either HIIT or MICT can improve cardiorespiratory fitness and glucose control and lead to reductions in TLR2 and TLR4 expression. MICT, which involved a longer duration of exercise, may be superior for reducing fasting glucose. PMID:26139217

  16. High-efficiency blue LEDs with thin AlGaN interlayers in InGaN/GaN MQWs grown on Si (111) substrates

    NASA Astrophysics Data System (ADS)

    Kimura, Shigeya; Yoshida, Hisashi; Ito, Toshihide; Okada, Aoi; Uesugi, Kenjiro; Nunoue, Shinya

    2016-02-01

    We demonstrate high-efficiency blue light-emitting diodes (LEDs) with thin AlGaN interlayers in InGaN/GaN multiquantum wells (MQWs) grown on Si (111) substrates. The peak external quantum efficiency (EQE) ηEQE of 82% at room temperature and the hot/cold factor (HCF) of 94% have been obtained by using the functional thin AlGaN interlayers in the MQWs in addition to reducing threading dislocation densities (TDDs) in the blue LEDs. An HCF is defined as ηEQE(85°C)/ηEQE(25°C). The blue LED structures were grown by metal-organic chemical vapor deposition on Si (111) substrates. The MQWs applied as an active layer have 8- pairs of InGaN/AlyGa1-yN/GaN (0<=y<=1) heterostructures. Thinfilm LEDs were fabricated by removing the Si (111) substrates from the grown layers. It is observed by high-resolution transmission electron microscopy and three-dimensional atom probe analysis that the 1 nm-thick AlyGa1-yN interlayers, whose Al content is y=0.3 or less, are continuously formed. EQE and the HCFs of the LEDs with thin Al0.15Ga0.85N interlayers are enhanced compared with those of the samples without the interlayers in the low-current-density region. We consider that the enhancement is due to both the reduction of the nonradiative recombination centers and the increase of the radiative recombination rate mediated by the strain-induced hole carriers indicated by the simulation of the energy band diagram.

  17. Preliminary results on high-total-dose testing of semiconductor photonic sources: a comparison of VCSELs and resonant-cavity LEDs

    NASA Astrophysics Data System (ADS)

    Berghmans, Francis; Coenen, Simon; Brichard, Benoit; Vos, Frans; Decreton, Marc C.; Verschaffelt, Guy; de la Fuente, Alexis; Veretennicoff, Irina P.; Thienpont, Hugo; Bockstaele, Ronny; Bienstman, Peter; Sys, Carl; Dhoedt, Bart; Moerman, Ingrid; Baets, Roel G.; Van Daele, Peter; Jonsson, Jan

    1998-10-01

    Low-power consumption, high efficiency and high bandwidth surface emitting semiconductor optical sources are critical elements in the development of future photonic systems for space and civil nuclear applications. In this paper, we report on preliminary high total dose experiments performed on two types of recently developed microcavity emitters: VCSELs and microcavity (or resonant cavity) LEDs. We gamma irradiated a total of twelve commercially available packaged VCSELs and two home-made flip-chipped 2 X 2 microcavity LED arrays. For doses between 5(DOT)106 Gy and 1.3(DOT)107 Gy the VCSELs show a threshold current increase lower than 20% and an output power decrease lower than 10%. These values are even smaller if the VCSEL is operated at a higher temperature. At a dose of 3.14(DOT)107 Gy, one VCSEL still showed satisfactory operation. The microcavity LEDs suffered from a burn-in after radiation but recovered quickly when biased. Their output power decrease is comparable to that of the VCSELs, while their quantum efficiency is not much affected. The specifications of both types of devices are not substantially altered by high gamma doses and can therefore be considered for application in enhanced radiation environments.

  18. Functional Analysis in Long-Term Operation of High Power UV-LEDs in Continuous Fluoro-Sensing Systems for Hydrocarbon Pollution.

    PubMed

    Arques-Orobon, Francisco Jose; Nuñez, Neftali; Vazquez, Manuel; Gonzalez-Posadas, Vicente

    2016-01-01

    This work analyzes the long-term functionality of HP (High-power) UV-LEDs (Ultraviolet Light Emitting Diodes) as the exciting light source in non-contact, continuous 24/7 real-time fluoro-sensing pollutant identification in inland water. Fluorescence is an effective alternative in the detection and identification of hydrocarbons. The HP UV-LEDs are more advantageous than classical light sources (xenon and mercury lamps) and helps in the development of a low cost, non-contact, and compact system for continuous real-time fieldwork. This work analyzes the wavelength, output optical power, and the effects of viscosity, temperature of the water pollutants, and the functional consistency for long-term HP UV-LED working operation. To accomplish the latter, an analysis of the influence of two types 365 nm HP UV-LEDs degradation under two continuous real-system working mode conditions was done, by temperature Accelerated Life Tests (ALTs). These tests estimate the mean life under continuous working conditions of 6200 h and for cycled working conditions (30 s ON & 30 s OFF) of 66,000 h, over 7 years of 24/7 operating life of hydrocarbon pollution monitoring. In addition, the durability in the face of the internal and external parameter system variations is evaluated. PMID:26927113

  19. Functional Analysis in Long-Term Operation of High Power UV-LEDs in Continuous Fluoro-Sensing Systems for Hydrocarbon Pollution

    PubMed Central

    Arques-Orobon, Francisco Jose; Nuñez, Neftali; Vazquez, Manuel; Gonzalez-Posadas, Vicente

    2016-01-01

    This work analyzes the long-term functionality of HP (High-power) UV-LEDs (Ultraviolet Light Emitting Diodes) as the exciting light source in non-contact, continuous 24/7 real-time fluoro-sensing pollutant identification in inland water. Fluorescence is an effective alternative in the detection and identification of hydrocarbons. The HP UV-LEDs are more advantageous than classical light sources (xenon and mercury lamps) and helps in the development of a low cost, non-contact, and compact system for continuous real-time fieldwork. This work analyzes the wavelength, output optical power, and the effects of viscosity, temperature of the water pollutants, and the functional consistency for long-term HP UV-LED working operation. To accomplish the latter, an analysis of the influence of two types 365 nm HP UV-LEDs degradation under two continuous real-system working mode conditions was done, by temperature Accelerated Life Tests (ALTs). These tests estimate the mean life under continuous working conditions of 6200 h and for cycled working conditions (30 s ON & 30 s OFF) of 66,000 h, over 7 years of 24/7 operating life of hydrocarbon pollution monitoring. In addition, the durability in the face of the internal and external parameter system variations is evaluated. PMID:26927113

  20. High-Performance Simultaneous Two-Photon Absorption Upconverted Stimulated Single-Component Sr2V2O7 Phosphor for White LEDs

    NASA Astrophysics Data System (ADS)

    Pan, Hong; Zhang, Lei; Jin, Long; Zhang, Binbin; Yang, Weiqing

    2015-10-01

    Notwithstanding the wide use of white light-emitting diodes (w-LEDs), conventionally consisting of multiple emitting components, some inevitable issues still exist nowadays, such as the intrinsic color balance, device complexity, and high cost associated with such multiple emitting components. We have synthesized simultaneous two-photon absorption upconverted stimulated single-component Sr2V2O7 phosphor for use in w-LEDs. Due to the photon avalanche upconversion, the as-grown phosphor exhibits an enhanced photoluminescence spectrum in the range of 400 nm to 650 nm for white light when excited by red light at 693 nm. Moreover, when evenly dispersed in polyethylene glycol dispersant, the as-grown phosphor simultaneously produced strong visible white light when using an excitation wavelength λ ex of 693 nm, suggesting a possible route to produce w-LEDs by using red chips as an excellent substitute for traditional w-LEDs with multiple emitting components based on rare-earth metals. Finally, density functional calculations were performed using the generalized gradient approximation to study the electronic structure of Sr2V2O7 crystal. A reasonable model is proposed to explain the two-photon absorption luminescence mechanism.