WorldWideScience

Sample records for led structures based

  1. Palladium-based on-wafer electroluminescence studies of GaN-based LED structures

    Energy Technology Data Exchange (ETDEWEB)

    Salcianu, C.O.; Thrush, E.J.; Humphreys, C.J. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Plumb, R.G. [Centre for Photonic Systems, Department of Engineering, University of Cambridge, Cambridge CB3 0FD (United Kingdom); Boyd, A.R.; Rockenfeller, O.; Schmitz, D.; Heuken, M. [AIXTRON AG, Kackertstr. 15-17, 52072 Aachen (Germany)

    2008-07-01

    Electroluminescence (EL) testing of Light Emitting Diode (LED) structures is usually done at the chip level. Assessing the optical and electrical properties of LED structures at the wafer scale prior to their processing would improve the cost effectiveness of producing LED-lamps. A non-destructive method for studying the luminescence properties of the structure at the wafer-scale is photoluminescence (PL). However, the relationship between the on-wafer PL data and the final device EL can be less than straightforward (Y. H Aliyu et al., Meas. Sci. Technol. 8, 437 (1997)) as the two techniques employ different carrier injection mechanisms. This paper provides an overview of some different techniques in which palladium is used as a contact in order to obtain on-wafer electroluminescence information which could be used to screen wafers prior to processing into final devices. Quick mapping of the electrical and optical characteristics was performed using either palladium needle electrodes directly, or using the latter in conjunction with evaporated palladium contacts to inject both electrons and holes into the active region via the p-type capping layer of the structure. For comparison, indium was also used to make contact to the n-layer so that electrons could be directly injected into that layer. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Effectiveness of structured, hospital-based, nurse-led atrial fibrillation clinics

    DEFF Research Database (Denmark)

    Qvist, Ina; Hendriks, Jeroen M L; Møller, Dorthe S

    2016-01-01

    -led, structured hospital AF clinics with the outcomes of a randomised trial of the efficacy of a nurse-led AF clinic, with respect to a composite outcome of cardiovascular-related hospitalisation and death. METHODS: All patients were referred to the AF nurse specialist by cardiologists. The AF nurse specialist......OBJECTIVE: A previous randomised trial showed that structured, nurse-led atrial fibrillation (AF) care is superior to conventional AF care, although further research is needed to determine the outcomes of such care in a real-world setting. We compared the outcomes of patients in real-world, nurse....... The composite primary end point occurred with an incidence rate of 8.0 (95% CI 6.1 to 10.4) per 100 person-years in the real-world population and 8.3 (95% CI 6.3 to 10.9) per 100 person-years in the clinical trial, with a crude HR of 0.83 (95% CI 0.56 to 1.23). CONCLUSIONS: Structured, nurse-led, hospital...

  3. Goniometric characterization of LED based greenhouse lighting

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Corell, Dennis Dan

    2015-01-01

    This paper describes a demonstration of goniospectroradiometry for characterizations of new light emitting diode (LED) based luminaries for enhanced photosynthesis in greenhouses. It highlights the differences between measurement of the traditional high pressure sodium (HPS) luminaries and the LED...... based luminaries. The LED based luminaries are compared to traditional HPS luminaries; in terms of energy efficiency with regard to the photosynthetic photon flux, and the LED luminaries were found to be more effective than the HPS luminaries...

  4. Goniometric characterization of LED based greenhouse lighting

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Corell, Dennis Dan

    2015-01-01

    This paper describes a demonstration of goniospectroradiometry for characterizations of new light emitting diode (LED) based luminaries for enhanced photosynthesis in greenhouses. It highlights the differences between measurement of the traditional high pressure sodium (HPS) luminaries and the LED...

  5. Magnetic-mechanical-electrical-optical coupling effects in GaN-based LED/rare-earth terfenol-D structures.

    Science.gov (United States)

    Peng, Mingzeng; Zhang, Yan; Liu, Yudong; Song, Ming; Zhai, Junyi; Wang, Zhong Lin

    2014-10-22

    A multi-field coupling structure is designed and investigated, which combines GaN-based optoelectronic devices and Terfenol-D. The abundant coupling effects and multifunctionalities among magnetics, mechanics, electrics, and optics are investigated by a combination of non-magnetic GaN-based piezoelectronic optoelectronic characteristics and the giant magnetomechanical properties of Terfenol-D. A few potential new areas of studies are proposed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Recent Advances of Graphitic Carbon Nitride-Based Structures and Applications in Catalyst, Sensing, Imaging, and LEDs

    Science.gov (United States)

    Wang, Aiwu; Wang, Chundong; Fu, Li; Wong-Ng, Winnie; Lan, Yucheng

    2017-10-01

    The graphitic carbon nitride (g-C3N4) which is a two-dimensional conjugated polymer has drawn broad interdisciplinary attention as a low-cost, metal-free, and visible-light-responsive photocatalyst in the area of environmental remediation. The g-C3N4-based materials have excellent electronic band structures, electron-rich properties, basic surface functionalities, high physicochemical stabilities and are "earth-abundant." This review summarizes the latest progress related to the design and construction of g-C3N4-based materials and their applications including catalysis, sensing, imaging, and white-light-emitting diodes. An outlook on possible further developments in g-C3N4-based research for emerging properties and applications is also included.

  7. Preliminary investigations of piezoelectric based LED luminary

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Andersen, Michael A. E.; Meyer, Kaspar Sinding

    2011-01-01

    This paper presents a preliminary study of PT (Piezoelectric Transformer) based SMPS’s (Switch Mode Power Supplies) for LED luminary. The unique properties of PTs (efficiency, power density and EMI) make them highly suitable for this application. Power stage topologies, rectifiers circuits...

  8. LED structure with enhanced mirror reflectivity

    Science.gov (United States)

    Bergmann, Michael; Donofrio, Matthew; Heikman, Sten; Schneider, Kevin S; Haberern, Kevin W; Edmond, John A

    2014-04-01

    Embodiments of the present invention are generally related to LED chips having improved overall emission by reducing the light-absorbing effects of barrier layers adjacent mirror contacts. In one embodiment, a LED chip comprises one or more LEDs, with each LED having an active region, a first contact under the active region having a highly reflective mirror, and a barrier layer adjacent the mirror. The barrier layer is smaller than the mirror such that it does not extend beyond the periphery of the mirror. In another possible embodiment, an insulator is further provided, with the insulator adjacent the barrier layer and adjacent portions of the mirror not contacted by the active region or by the barrier layer. In yet another embodiment, a second contact is provided on the active region. In a further embodiment, the barrier layer is smaller than the mirror such that the periphery of the mirror is at least 40% free of the barrier layer, and the second contact is below the first contact and accessible from the bottom of the chip.

  9. Preliminary investigations of piezoelectric based LED luminary

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Andersen, Michael A. E.; Meyer, Kaspar Sinding

    2011-01-01

    This paper presents a preliminary study of PT (Piezoelectric Transformer) based SMPS’s (Switch Mode Power Supplies) for LED luminary. The unique properties of PTs (efficiency, power density and EMI) make them highly suitable for this application. Power stage topologies, rectifiers circuits, modul....... The prototype constitutes a light source equivalent to the 40 W incandescent bulb. Experimental results shows, that the prototype are capable of ZVS and dimming (the later trough use of burst mode control)....

  10. Luminaries-level structure improvement of LEDs for heat dissipation ...

    Indian Academy of Sciences (India)

    Heat dissipation enhancement of LED luminaries is of great significance to the large-scale application of LED. Luminaries-level structure improvement by the method of boring through-hole is adopted to intensify heat dissipation. Furthermore, the natural convection heat transfer process of LED luminaries is simulated by ...

  11. System Reliability for LED-Based Products

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J Lynn; Mills, Karmann; Lamvik, Michael; Yaga, Robert; Shepherd, Sarah D; Bittle, James; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy; Johnson, Cortina; Evans, Amy

    2014-04-07

    Results from accelerated life tests (ALT) on mass-produced commercially available 6” downlights are reported along with results from commercial LEDs. The luminaires capture many of the design features found in modern luminaires. In general, a systems perspective is required to understand the reliability of these devices since LED failure is rare. In contrast, components such as drivers, lenses, and reflector are more likely to impact luminaire reliability than LEDs.

  12. LED Virtual Simulation based on Web3D

    OpenAIRE

    Lilan Liu; Liu Han; Zhiqi Lin; Manping Li; Tao Yu

    2014-01-01

    Regarding to the high price and low market popularity of current LED indoor lighting products, a LED indoor lighting platform is proposed based on Web3D technology. The internet virtual reality technology is integrated and applied into the LED collaborative e-commerce website with Virtools. According to the characteristics of the LED indoor lighting products, this paper introduced the method to build encapsulated model and three characteristics of LED lighting: geometrical, optical and behavi...

  13. Luminaries-level structure improvement of LEDs for heat dissipation ...

    Indian Academy of Sciences (India)

    Furthermore, the natural convection heat transfer process of LED luminaries is simulated by computational fluid dynamics (CFD) model before and after the structural modification. As shown by computational results, boring through-hole is beneficial to develop bottomto-top natural convection, eliminate local circumfluence, ...

  14. Development of highly durable deep-ultraviolet AlGaN-based LED multichip array with hemispherical encapsulated structures using a selected resin through a detailed feasibility study

    Science.gov (United States)

    Nagai, Shoko; Yamada, Kiho; Hirano, Akira; Ippommatsu, Masamichi; Ito, Masahiro; Morishima, Naoki; Aosaki, Ko; Honda, Yoshio; Amano, Hiroshi; Akasaki, Isamu

    2016-08-01

    To replace mercury lamps with AlGaN-based deep-ultraviolet (DUV) LEDs, a simple and low-cost package with increased light extraction efficiency (LEE) is indispensable. Therefore, resin encapsulation is considered to be a key technology. However, the photochemical reactions induced by DUV light cause serious problems, and conventional resins cannot be used. In the former part of this study, a comparison of a silicone resin and fluorine polymers was carried out in terms of their suitability for encapsulation, and we concluded that only one of the fluorine polymers can be used for encapsulation. In the latter part, the endurance of encapsulation using the selected fluorine polymer was investigated, and we confirmed that the selected fluorine polymer can guarantee a lifetime of over 6,000 h at a wavelength of 265 nm. Furthermore, a 3 × 4 array module of encapsulated dies on a simple AlN submount was fabricated, demonstrating the possibility of W/cm2-class lighting.

  15. Integrated LED-based luminaire for general lighting

    Science.gov (United States)

    Dowling, Kevin J.; Lys, Ihor A.; Williamson, Ryan C.; Roberge, Brian; Roberts, Ron; Morgan, Frederick; Datta, Michael Jay; Mollnow, Tomas Jonathan

    2016-08-30

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  16. Integrated LED-based luminare for general lighting

    Science.gov (United States)

    Dowling, Kevin J.; Lys, Ihor A.; Roberge, Brian; Williamson, Ryan C.; Roberts, Ron; Datta, Michael; Mollnow, Tomas; Morgan, Frederick M.

    2013-03-05

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  17. Conduction-driven cooling of LED-based automotive LED lighting systems for abating local hot spots

    Science.gov (United States)

    Saati, Ferina; Arik, Mehmet

    2018-02-01

    Light-emitting diode (LED)-based automotive lighting systems pose unique challenges, such as dual-side packaging (front side for LEDs and back side for driver electronics circuit), size, harsh ambient, and cooling. Packaging for automotive lighting applications combining the advanced printed circuit board (PCB) technology with a multifunctional LED-based board is investigated with a focus on the effect of thermal conduction-based cooling for hot spot abatement. A baseline study with a flame retardant 4 technology, commonly known as FR4 PCB, is first compared with a metal-core PCB technology, both experimentally and computationally. The double-sided advanced PCB that houses both electronics and LEDs is then investigated computationally and experimentally compared with the baseline FR4 PCB. Computational models are first developed with a commercial computational fluid dynamics software and are followed by an advanced PCB technology based on embedded heat pipes, which is computationally and experimentally studied. Then, attention is turned to studying different heat pipe orientations and heat pipe placements on the board. Results show that conventional FR4-based light engines experience local hot spots (ΔT>50°C) while advanced PCB technology based on heat pipes and thermal spreaders eliminates these local hot spots (ΔT<10°C), leading to a higher lumen extraction with improved reliability. Finally, possible design options are presented with embedded heat pipe structures that further improve the PCB performance.

  18. A synthetic method of solar spectrum based on LED

    Science.gov (United States)

    Wang, Ji-qiang; Su, Shi; Zhang, Guo-yu; Zhang, Jian

    2017-10-01

    A synthetic method of solar spectrum which based on the spectral characteristics of the solar spectrum and LED, and the principle of arbitrary spectral synthesis was studied by using 14 kinds of LED with different central wavelengths.The LED and solar spectrum data were selected by Origin Software firstly, then calculated the total number of LED for each center band by the transformation relation between brightness and illumination and Least Squares Curve Fit in Matlab.Finally, the spectrum curve of AM1.5 standard solar spectrum was obtained. The results met the technical indexes of the solar spectrum matching with ±20% and the solar constant with >0.5.

  19. Improved power quality based high brightness LED lamp driver ...

    African Journals Online (AJOL)

    This paper deals with a power factor corrected (PFC) improved power quality based LED lamp driver. The proposed driver consists of a PFC Cuk DC-DC converter which operates in continuous conduction mode (CCM) to improve the power quality at input AC mains. The design, modeling and simulation of an 18W LED (six ...

  20. Progress in extremely high brightness LED-based light sources

    Science.gov (United States)

    Hoelen, Christoph; Antonis, Piet; de Boer, Dick; Koole, Rolf; Kadijk, Simon; Li, Yun; Vanbroekhoven, Vincent; Van De Voorde, Patrick

    2017-09-01

    Although the maximum brightness of LEDs has been increasing continuously during the past decade, their luminance is still far from what is required for multiple applications that still rely on the high brightness of discharge lamps. In particular for high brightness applications with limited étendue, e.g. front projection, only very modest luminance values in the beam can be achieved with LEDs compared to systems based on discharge lamps or lasers. With dedicated architectures, phosphor-converted green LEDs for projection may achieve luminance values up to 200-300 Mnit. In this paper we report on the progress made in the development of light engines based on an elongated luminescent concentrator pumped by blue LEDs. This concept has recently been introduced to the market as ColorSpark High Lumen Density LED technology. These sources outperform the maximum brightness of LEDs by multiple factors. In LED front projection, green LEDs are the main limiting factor. With our green modules, we now have achieved peak luminance values of 2 Gnit, enabling LED-based projection systems with over 4000 ANSI lm. Extension of this concept to yellow and red light sources is presented. The light source efficiency has been increased considerably, reaching 45-60 lm/W for green under practical application conditions. The module architecture, beam shaping, and performance characteristics are reviewed, as well as system aspects. The performance increase, spectral range extensions, beam-shaping flexibility, and cost reductions realized with the new module architecture enable a breakthrough in LED-based projection systems and in a wide variety of other high brightness applications.

  1. Vision communications based on LED array and imaging sensor

    Science.gov (United States)

    Yoo, Jong-Ho; Jung, Sung-Yoon

    2012-11-01

    In this paper, we propose a brand new communication concept, called as "vision communication" based on LED array and image sensor. This system consists of LED array as a transmitter and digital device which include image sensor such as CCD and CMOS as receiver. In order to transmit data, the proposed communication scheme simultaneously uses the digital image processing and optical wireless communication scheme. Therefore, the cognitive communication scheme is possible with the help of recognition techniques used in vision system. By increasing data rate, our scheme can use LED array consisting of several multi-spectral LEDs. Because arranged each LED can emit multi-spectral optical signal such as visible, infrared and ultraviolet light, the increase of data rate is possible similar to WDM and MIMO skills used in traditional optical and wireless communications. In addition, this multi-spectral capability also makes it possible to avoid the optical noises in communication environment. In our vision communication scheme, the data packet is composed of Sync. data and information data. Sync. data is used to detect the transmitter area and calibrate the distorted image snapshots obtained by image sensor. By making the optical rate of LED array be same with the frame rate (frames per second) of image sensor, we can decode the information data included in each image snapshot based on image processing and optical wireless communication techniques. Through experiment based on practical test bed system, we confirm the feasibility of the proposed vision communications based on LED array and image sensor.

  2. Spatial layout optimization design of multi-type LEDs lighting source based on photoelectrothermal coupling theory

    Science.gov (United States)

    Xue, Lingyun; Li, Guang; Chen, Qingguang; Rao, Huanle; Xu, Ping

    2018-03-01

    Multiple LED-based spectral synthesis technology has been widely used in the fields of solar simulator, color mixing, and artificial lighting of plant factory and so on. Generally, amounts of LEDs are spatially arranged with compact layout to obtain the high power density output. Mutual thermal spreading among LEDs will produce the coupled thermal effect which will additionally increase the junction temperature of LED. Affected by the Photoelectric thermal coupling effect of LED, the spectrum of LED will shift and luminous efficiency will decrease. Correspondingly, the spectral synthesis result will mismatch. Therefore, thermal management of LED spatial layout plays an important role for multi-LEDs light source system. In the paper, the thermal dissipation network topology model considering the mutual thermal spreading effect among the LEDs is proposed for multi-LEDs system with various types of power. The junction temperature increment cased by the thermal coupling has the great relation with the spatial arrangement. To minimize the thermal coupling effect, an optimized method of LED spatial layout for the specific light source structure is presented and analyzed. The results showed that layout of LED with high-power are arranged in the corner and low-power in the center. Finally, according to this method, it is convenient to determine the spatial layout of LEDs in a system having any kind of light source structure, and has the advantages of being universally applicable to facilitate adjustment.

  3. Visualization of the 3D structures of small organisms via LED-SIM.

    Science.gov (United States)

    Ruan, Yongying; Dan, Dan; Zhang, Mengna; Bai, Ming; Lei, Ming; Yao, Baoli; Yang, Xingke

    2016-01-01

    Innovative new techniques that aid in the visualization of microscopic anatomical structures have improved our understanding of organismal biology significantly. It is often challenging to observe internal 3D structures, despite the use of techniques such as confocal laser scanning microscopy (CLSM), micro-computed tomography (Micro-CT), magnetic resonance imaging (MRI), focused ion beam scanning electron microscopy (FIB-SEM) and others. In the current paper, we assess LED-SIM (DMD-based LED-illumination structured illumination microscopy), which facilitates the acquisition of nano- and micro-3D structures of small organisms in a high-resolution format (500 nm in the XY-plane and 930 nm along the Z-axis). We compare other microstructural imaging techniques (involving conventional optical microscopy, CLSM and Micro-CT) with LED-SIM to assess the quality (e.g. resolution, penetration depth, etc.) of LED-SIM images, as well as to document the potential short-comings of LED-SIM. Based on these results we present an optimized set of protocols to ensure that LED-SIM arthropod and nematode samples with different cuticles or textures are prepared for analysis in an optimal manner. Six arthropod and nematode specimens were tested and shown to be suitable for LED-SIM imaging, which was found to yield high resolution 3D images. Although LED-SIM still must be thoroughly tested before it is widely accepted and the Z-axis resolution still requires improvement, this technique offers distinct high quality 3D images. LED-SIM can be highly effective and may provide high quality 3D images for zoological studies following the guidelines of sample preparation presented in the current paper.

  4. Design of an Oximeter Based on LED-LED Configuration and FPGA Technology

    OpenAIRE

    Stojanovic, Radovan; Karadaglic, Dejan

    2013-01-01

    A fully digital photoplethysmographic (PPG) sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED) for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA) is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (SpO2). The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (SpO2). N-LEDs...

  5. Visual color matching system based on RGB LED light source

    Science.gov (United States)

    Sun, Lei; Huang, Qingmei; Feng, Chen; Li, Wei; Wang, Chaofeng

    2018-01-01

    In order to study the property and performance of LED as RGB primary color light sources on color mixture in visual psychophysical experiments, and to find out the difference between LED light source and traditional light source, a visual color matching experiment system based on LED light sources as RGB primary colors has been built. By simulating traditional experiment of metameric color matching in CIE 1931 RGB color system, it can be used for visual color matching experiments to obtain a set of the spectral tristimulus values which we often call color-matching functions (CMFs). This system consists of three parts: a monochromatic light part using blazed grating, a light mixing part where the summation of 3 LED illuminations are to be visually matched with a monochromatic illumination, and a visual observation part. The three narrow band LEDs used have dominant wavelengths of 640 nm (red), 522 nm (green) and 458 nm (blue) respectively and their intensities can be controlled independently. After the calibration of wavelength and luminance of LED sources with a spectrophotometer, a series of visual color matching experiments have been carried out by 5 observers. The results are compared with those from CIE 1931 RGB color system, and have been used to compute an average locus for the spectral colors in the color triangle, with white at the center. It has been shown that the use of LED is feasible and has the advantages of easy control, good stability and low cost.

  6. LED-based digital hologram reconstruction by compressive sensing

    Science.gov (United States)

    Weng, Jiawen; Yang, Chuping; Qin, Yi; Li, Hai

    2015-10-01

    LED-based digital hologram, considered as low-coherence digital hologram, is confined to in-line holography because the interference fringes could be observed only when the angle between the object and reference wave is small enough. So, phase-shifting technique is usually employed. But it is not fit for dynamic analysis for demanding more than one hologram. A numerical reconstruction method based on compressive sensing theory for single LED-based digital hologram is proposed to achieve dynamic analysis. By this method, the out-of-focus twin image and the coherent noise can be inhibited to some extent. The theory is presented in detail, and experimental result on LED-based digital holography with USAF pattern as test target, is performed to demonstrate the feasibility and validity of the method.

  7. Novel thin-GaN LED structure adopted micro abraded surface to compare with conventional vertical LEDs in ultraviolet light

    Science.gov (United States)

    Chiang, Yen Chih; Lin, Chien Chung; Kuo, Hao Chung

    2015-04-01

    In this study, novel thin-GaN-based ultraviolet light-emitting diodes (NTG-LEDs) were fabricated using wafer bonding, laser lift-off, dry etching, textured surface, and interconnection techniques. Placing PN electrodes on the same side minimized the absorption caused by electrodes in conventional vertical injection light-emitting diodes (V-LEDs) and the current spreading was improved. The light output power (700 mA) of the NTG-LEDs was enhanced by 18.3% compared with that of the V-LEDs, and the external quantum efficiency (EQE) of the NTG-LEDs was also relatively enhanced by 20.0% compared with that of a reference device. When the current operations were 1,500 mA, the enhancements of the light output power and EQE were 27.4% and 27.2%, respectively. Additionally, the efficiency droop was improved by more than 15% at the same current level.

  8. Design of an oximeter based on LED-LED configuration and FPGA technology.

    Science.gov (United States)

    Stojanovic, Radovan; Karadaglic, Dejan

    2013-01-04

    A fully digital photoplethysmographic (PPG) sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED) for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA) is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (S(p)O(2)). The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (S(p)O(2)). N-LEDs configuration is proposed for multichannel S(p)O(2) measurements. The approach resulted in better spectral sensitivity, increased and adjustable resolution, reduced noise, small size, low cost and low power consumption.

  9. Design of an Oximeter Based on LED-LED Configuration and FPGA Technology

    Directory of Open Access Journals (Sweden)

    Radovan Stojanovic

    2013-01-01

    Full Text Available A fully digital photoplethysmographic (PPG sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (SpO2. The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (SpO2. N-LEDs configuration is proposed for multichannel SpO2 measurements. The approach resulted in better spectral sensitivity, increased and adjustable resolution, reduced noise, small size, low cost and low power consumption.

  10. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng

    2013-01-01

    Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

  11. Design of LED projector based on gradient-index lens

    Science.gov (United States)

    Qian, Liyong; Zhu, Xiangbing; Cui, Haitian; Wang, Yuanhang

    2018-01-01

    In this study, a new type of projector light path is designed to eliminate the deficits of existing projection systems, such as complex structure and low collection efficiency. Using a three-color LED array as the lighting source, by means of the special optical properties of a gradient-index lens, the complex structure of the traditional projector is simplified. Traditional components, such as the color wheel, relay lens, and mirror, become unnecessary. In this way, traditional problems, such as low utilization of light energy and loss of light energy, are solved. With the help of Zemax software, the projection lens is optimized. The optimized projection lens, LED, gradient-index lens, and digital micromirror device are imported into Tracepro. The ray tracing results show that both the utilization of light energy and the uniformity are improved significantly.

  12. [Photoelectric parametric test system of LED based on virtual instrument].

    Science.gov (United States)

    Yang, Song-Tao; Wang, Jing; Wang, Li-Dong; Liang, Pei; Dong, Qian-Min

    2014-11-01

    The standardized measuring principle, requirements and implementations of the above parameters of LEDs were researched and analyzed in the present paper. Then a comprehensive test system involved with optics, machinery and computer was designed to accomplish data acquisition, algorithm design and interface design on virtual instrument using NI data acquisition card USB6210. And convincing results of LEDs' parameters, including peak wavelength, width of half-peak wavelength, centroid wavelength, chromaticity coordinates, purity, correlated color temperature and the forward voltage/current, were achieved with good consistency based on the measured spectrum. The system owns simple interface, reliable algorithms and stable results. Respective measurements on five kinds of color of LED result in an average error less than 3%, which show an ideal performance of the system.

  13. A novel LED-based device for occlusal caries detection.

    Science.gov (United States)

    Aktan, Ali Murat; Cebe, Mehmet Ata; Ciftçi, Mehmet Ertuğrul; Sirin Karaarslan, Emine

    2012-11-01

    The aim of this in-vitro study was to compare the performance of laser-based (DIAGNOdent, KaVo, Biberach, Germany) and LED-based (Midwest Caries I.D., DENTSPLY Professional, New York, USA) caries detectors in the detection of occlusal caries in permanent molars. The study consisted of 129 visually sound or non-cavitated pits or fissures in 82 extracted permanent human molar teeth. Two trained examiners used the laser-based and LED-based caries detectors to examine the fissures for caries. The teeth were then sectioned at the surfaces suspected of containing occlusal caries and histologically evaluated using stereomicroscopy as a gold standard. Inter-examiner reliability of the caries detector examination was assessed using Cohen's Kappa statistics. The sensitivity, specificity, and accuracy in diagnosing occlusal caries using the two devices were calculated according to appropriate cut-off scores. Receiver operating characteristic (ROC) curves were also determined to compare the diagnostic performance of the devices in occlusal caries diagnosis. The cut-off level of significance was taken as p = 0.005. Cohen's Kappa showed substantial agreement for the laser-based caries detector (0.74), and almost perfect agreement for the LED-based (0.89) caries detector. The specificity of the laser-based device varied from 0.49 to 0.97 at T1 and T2. Its sensitivity varied from 0.33 to 0.65 at T1 and T2. The specificity of the LED-based device varied from 0.48 to 0.56 at T1 and T2. Its sensitivity varied from 0.65 to 0.84 at T1 and from 0.80 to 0.84 at T2. Taking the limitations of the current study into consideration, the DIAGNOdent laser pen was more accurate in determining when teeth were free of occlusal caries than was the Midwest Caries I.D. LED-based device, although the Midwest Caries I.D. device more often revealed the presence of occlusal caries than did the DIAGNOdent pen.

  14. Luminaries-level structure improvement of LEDs for heat dissipation ...

    Indian Academy of Sciences (India)

    Due to its significant advantages such as high efficiency, long lifetime, low power consump- tion, inconceivable controllability and high ... However, till now LED chip can only convert 20% of the input power into light while the rest 80% is converted ... the middle of computational domain. Turbulence natural convection and ...

  15. A self-calibrating led-based solar test platform

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Sylvester-Hvid, Kristian O.; Jørgensen, Mikkel

    2011-01-01

    A compact platform for testing solar cells is presented. The light source comprises a multi-wavelength high-power LED (light emitting diode) array allowing the homogenous illumination of small laboratory solar cell devices (substrate size 50 × 25 mm) within the 390–940 nm wavelength range......, it is possible to perform all the commonly employed measurements on the solar cell at very high speed without moving the sample. In particular, the LED-based illumination system provides an alternative to light-biased incident photon-to-current efficiency measurement to be performed which we demonstrate. Both...... top and bottom contact is possible and the atmosphere can be controlled around the sample during measurements. The setup was developed for the field of polymer and organic solar cells with particular emphasis on enabling different laboratories to perform measurements in the same manner and obtain...

  16. LED-Based High-Voltage Lines Warning System

    Directory of Open Access Journals (Sweden)

    Eldar MUSA

    2013-04-01

    Full Text Available LED-based system, running with the current of high-voltage lines and converting the current flowing through the line into the light by using a toroid transformer, has been developed. The transformer’s primary winding is constituted by the high voltage power line. Toroidal core consists of two equal parts and the secondary windings are evenly placed on these two parts. The system is mounted on the high-voltage lines as a clamp. The secondary winding ends are connected in series by the connector on the clamp. LEDs are supplied by the voltage at the ends of secondary. Current flowing through highvoltage transmission lines is converted to voltage by the toroidal transformer and the light emitting LEDs are supplied with this voltage. The theory of the conversion of the current flowing through the line into the light is given. The system, running with the current of the line and converting the current into the light, has been developed. System has many application areas such as warning high voltage lines (warning winches to not hinder the high-voltage lines when working under the lines, warning planes to not touch the high-voltage lines, remote measurement of high-voltage line currents, and local illumination of the line area

  17. Novel Carbazole Skeleton-Based Photoinitiators for LED Polymerization and LED Projector 3D Printing

    Directory of Open Access Journals (Sweden)

    Assi Al Mousawi

    2017-12-01

    Full Text Available Radical chemistry is a very convenient way to produce polymer materials. Here, an application of a particular photoinduced radical chemistry is illustrated. Seven new carbazole derivatives Cd1–Cd7 are incorporated and proposed as high performance near-UV photoinitiators for both the free radical polymerization (FRP of (methacrylates and the cationic polymerization (CP of epoxides utilizing Light Emitting Diodes LEDs @405 nm. Excellent polymerization-initiating abilities are found and high final reactive function conversions are obtained. Interestingly, these new derivatives display much better near-UV polymerization-initiating abilities compared to a reference UV absorbing carbazole (CARET 9H-carbazole-9-ethanol demonstrating that the new substituents have good ability to red shift the absorption of the proposed photoinitiators. All the more strikingly, in combination with iodonium salt, Cd1–Cd7 are likewise preferred as cationic photoinitiators over the notable photoinitiator bis(2,4,6-trimethylbenzoylphenylphosphine oxide (BAPO for mild irradiation conditions featuring their remarkable reactivity. In particular their utilization in the preparation of new cationic resins for LED projector 3D printing is envisioned. A full picture of the included photochemical mechanisms is given.

  18. Instructor-led or Learner-led for Elementary Learners to Learn Computer-based Music Composition?

    OpenAIRE

    Ju-Shih Tseng; Ming-Puu Chen

    2010-01-01

    The purpose of the present study was to examine the effects of instructional strategy (instructor-led vs. learner-led) and grade level (third grade vs. fifth grade) on elementary learners’ music composition performance and attitude with the use of a computer-based music composition software. An experimental learning activity was implemented using 5E learning cycle as a pedagogical framework to facilitate learning. A quasi-experimental design was employed with elementary learners participated ...

  19. Frontiers of Crystallography: A Project-Based Research-Led Learning Exercise

    Science.gov (United States)

    Wilson, Chick C.; Parkin, Andrew; Thomas, Lynne H.

    2012-01-01

    A highly interactive research-led learning session for chemistry undergraduates is described, which aims to lead students to an awareness of the applications of crystallography technique through a mentored hands-on crystal structure solution and refinement session. The research-based environment is inherent throughout the 4.5 h program and is…

  20. The characteristics of GaN-based blue LED on Si substrate

    International Nuclear Information System (INIS)

    Xiong Chuanbing; Jiang Fengyi; Fang Wenqing; Wang Li; Mo Chunnan; Liu Hechu

    2007-01-01

    InGaN multiple quantum well (MQW) light-emitting diodes (LEDs), grown by metalorganic chemical vapor deposition (MOCVD) on Si (1 1 1) substrates, were successfully bonded and transferred onto new Si substrate. After chemical etching Si substrate and inductively coupled plasma (ICP) etching buffer layer, vertical structure GaN blue LEDs were fabricated. The characteristics of the lateral structure LEDs (grown on Si substrate) and the vertical structure LEDs (bonded on new Si substrate) have been investigated, and the performance of the vertical structure LEDs have obviously been improved compared to the lateral structure LEDs. The improved performance is due to the smaller tensile stress and series resistance in the vertical LEDs than that in lateral LEDs. The electroluminescence difference between vertical LEDs chips and the vertical LEDs lamps can be explained by the difference in heat dissipation

  1. A novel amblyopia treatment system based on LED light source

    Science.gov (United States)

    Zhang, Xiaoqing; Chen, Qingshan; Wang, Xiaoling

    2011-05-01

    A novel LED (light emitting diode) light source of five different colors (white, red, green, blue and yellow) is adopted instead of conventional incandescent lamps for an amblyopia treatment system and seven training methods for rectifying amblyopia are incorporated so as for achieving an integrated therapy. The LED light source is designed to provide uniform illumination, adjustable light intensity and alterable colors. Experimental tests indicate that the LED light source operates steadily and fulfills the technical demand of amblyopia treatment.

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

    Science.gov (United States)

    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.

  3. Instructor-led or Learner-led for Elementary Learners to Learn Computer-based Music Composition?

    Directory of Open Access Journals (Sweden)

    Ju-Shih Tseng

    2010-03-01

    Full Text Available The purpose of the present study was to examine the effects of instructional strategy (instructor-led vs. learner-led and grade level (third grade vs. fifth grade on elementary learners’ music composition performance and attitude with the use of a computer-based music composition software. An experimental learning activity was implemented using 5E learning cycle as a pedagogical framework to facilitate learning. A quasi-experimental design was employed with elementary learners participated in the experiment. The results revealed that (a fifth grader outperformed third graders in creativity, whereas third graders were extrinsically motivated and perceived that the computer-based music composition software was useful in learning music composition more than fifth graders were and did; and (b learners with instructor-led instructional strategy outperformed learners with learned-led instructional strategy in creativity and craftsmanship and held high extrinsic motivation than learners with learner-led. The implementations and suggestions for future study were discussed in the present study.

  4. A Simulation-Based LED Design Project in Photonics Instruction Based on Industry-University Collaboration

    Science.gov (United States)

    Chang, S. -H.; Chen, M. -L.; Kuo, Y. -K.; Shen, Y. -C.

    2011-01-01

    In response to the growing industrial demand for light-emitting diode (LED) design professionals, based on industry-university collaboration in Taiwan, this paper develops a novel instructional approach: a simulation-based learning course with peer assessment to develop students' professional skills in LED design as required by industry as well as…

  5. [Analysis of color gamut of LCD system based on LED backlight with area-controlling technique].

    Science.gov (United States)

    Li, Fu-Wen; Jin, Wei-Qi; Shao, Xi-Bin; Zhang, Li-Lei; Wan, Li-Fang

    2010-05-01

    Color gamut as a significant performance index for display system describes the color reproduction ability IN real scenes. Liquid crystal display (LCD) is the most popular technology in flat panel display. However, conventional cold cathode fluorescent lamp (CCFL) backlight of LCD can not behave high color gamut compared with cathode ray tube (CRT). The common used method of color gamut measuring for LCD system is introduced at the beginning. According to the inner structure and display principle of LCD system, there are three major factors deciding LCD's color gamut: spectral properties of backlight, transmittance properties of color filters and performance of liquid crystal panel. Instead of conventional backlight CCFL, RGB-LED backlight is used for improving color reproduction of LCD display system. Due to the imperfect match between RGB-LED' s spectra and color filter's transmittance, the color filter would reduce the color gamut of LCD system more or less. Therefore, LCD system based on LED backlight with area-control technique is introduced which modifies backlight control signal according to the input signal After analyzing and calculating the spectra of LED backlight which passes through the color filters using method of colorimetry, the area sizes of color gamut triangles of RGB-LED backlight with area-control and RGB-LED backlight without area-control LCD systems are compared and the relationship between color gamut and varying contrast of liquid crystal panel is analyzed. It is indicated that LED backlight with area-control technique can avoid color saturation dropping and have little effects on the contrast variation of liquid crystal panel. In other words, LED backlight with area-control technique relaxes the requirements of both color filter performance and liquid crystal panel. Thus, it is of importance to improve the color gamut of the current LCD system with area-control LED backlight.

  6. Review: Silicon-based oxynitride and nitride phosphors for white LEDs

    Directory of Open Access Journals (Sweden)

    Rong-Jun Xie and Naoto Hirosaki

    2007-01-01

    Full Text Available As a novel class of inorganic phosphors, oxynitride and nitride luminescent materials have received considerable attention because of their potential applications in solid-state lightings and displays. In this review we focus on recent developments in the preparation, crystal structure, luminescence and applications of silicon-based oxynitride and nitride phosphors for white light-emitting diodes (LEDs. The structures of silicon-based oxynitrides and nitrides (i.e., nitridosilicates, nitridoaluminosilicates, oxonitridosilicates, oxonitridoaluminosilicates, and sialons are generally built up of networks of crosslinking SiN4 tetrahedra. This is anticipated to significantly lower the excited state of the 5d electrons of doped rare-earth elements due to large crystal-field splitting and a strong nephelauxetic effect. This enables the silicon-based oxynitride and nitride phosphors to have a broad excitation band extending from the ultraviolet to visible-light range, and thus strongly absorb blue-to-green light. The structural versatility of oxynitride and nitride phosphors makes it possible to attain all the emission colors of blue, green, yellow, and red; thus, they are suitable for use in white LEDs. This novel class of phosphors has demonstrated its superior suitability for use in white LEDs and can be used in bichromatic or multichromatic LEDs with excellent properties of high luminous efficacy, high chromatic stability, a wide range of white light with adjustable correlated color temperatures (CCTs, and brilliant color-rendering properties.

  7. High Output LED-Based Profile Lighting Fixture

    DEFF Research Database (Denmark)

    Török, Lajos; Beczkowski, Szymon; Munk-Nielsen, Stig

    2011-01-01

    Recent developments in power light emitting diode (LED) industry have made LEDs suitable for being efficiently used in high intensity lighting fixtures instead of the commonly used high intensity discharge (HID) lamps. A high output LEDbased profile-light fixture is presented in this paper...... the grid and delivers the required voltage to the LEDdriver which is a dual interleaved buck converter. Twelve highpower CBT-90 LEDs have been connected in a 4xRGBconfiguration to deliver high output of saturated colors without the need for subtractive color filters. More than 6000 lm of fixture light...

  8. LED Based Optical Wireless Communication System for WBAN

    Directory of Open Access Journals (Sweden)

    ATTIYA BAQAI

    2016-10-01

    Full Text Available In this paper the O-WBANs (Optical Wireless Body Area Networks is presented as an alternative to the radio and microwave BANs which are plagued with issues like interference, power hungry, hazardous and costly spectrum. Various experiments performed in this work demonstrate the feasibility of LED (Light-Emitting Diode based optical systems to be used for BANs. The system cost is kept as low as possible. Mainly the effects on the optical link are observed under ambient light and with different modulation schemes by varying link distance and line of sight in this paper. Experimental results reveal the satisfactory link availability up to the distance of 7 feet (around 2m, the optimum range of WBAN and within the field of view of 30-60º. The low cost solution presented in this paper meets the WBANs data rate requirement for physiological data (i.e. 10-100 kbps. As IR (Infra-Red signals do not provide any interference with the signals generated by the medical equipment of hospitals which is the problem in case of RF or microwave signals, additionally the IR signals are confined within a room hence IR signaling can prove to be potential candidate for WBAN fulfilling its security and limited access requirement.

  9. Optimal colour quality of LED clusters based on memory colours.

    Science.gov (United States)

    Smet, Kevin; Ryckaert, Wouter R; Pointer, Michael R; Deconinck, Geert; Hanselaer, Peter

    2011-03-28

    The spectral power distributions of tri- and tetrachromatic clusters of Light-Emitting-Diodes, composed of simulated and commercially available LEDs, were optimized with a genetic algorithm to maximize the luminous efficacy of radiation and the colour quality as assessed by the memory colour quality metric developed by the authors. The trade-off of the colour quality as assessed by the memory colour metric and the luminous efficacy of radiation was investigated by calculating the Pareto optimal front using the NSGA-II genetic algorithm. Optimal peak wavelengths and spectral widths of the LEDs were derived, and over half of them were found to be close to Thornton's prime colours. The Pareto optimal fronts of real LED clusters were always found to be smaller than those of the simulated clusters. The effect of binning on designing a real LED cluster was investigated and was found to be quite large. Finally, a real LED cluster of commercially available AlGaInP, InGaN and phosphor white LEDs was optimized to obtain a higher score on memory colour quality scale than its corresponding CIE reference illuminant.

  10. Self-aligning LED-based optical link

    Science.gov (United States)

    Shen, Thomas C.; Drost, Robert J.; Rzasa, John R.; Sadler, Brian M.; Davis, Christopher C.

    2016-09-01

    The steady advances in light-emitting diode (LED) technology have motivated the use of LEDs in optical wireless communication (OWC) applications such as indoor local area networks (LANs) and communication between mobile platforms (e.g., robots, vehicles). In contrast to traditional radio frequency (RF) wireless communication, OWC utilizes electromagnetic spectrum that is largely unregulated and unrestricted. OWC communication may be especially useful in RF-denied environments, in which RF communication may be prohibited or undesirable. However, OWC does present some challenges, including the need to maintain alignment between potentially moving nodes. We describe a novel system for link alignment that is composed of a hyperboloidal mirror, camera, and gimbal. The experimental system is able to use the mirror and camera to detect an LED beacon of a neighboring node and estimate its bearing (azimuth and elevation), point the gimbal towards the beacon, and establish an optical link.

  11. Control and Driving Methods for LED Based Intelligent Light Sources

    DEFF Research Database (Denmark)

    Beczkowski, Szymon

    High power light-emitting diodes allow the creation of luminaires capable of generating saturated colour light at very high efficacies. Contrary to traditional light sources like incandescent and high-intensity discharge lamps, where colour is generated using filters, LEDs use additive light mixing......, where the intensity of each primary colour diode has to be adjusted to the needed intensity to generate specified colour. The function of LED driver is to supply the diode with power needed to achieve the desired intensity. Typically, the drivers operate as a current source and the intensity...... of the diode is controlled either by varying the magnitude of the current or by driving the LED with a pulsed current and regulate the width of the pulse. It has been shown previously, that these two methods yield different effects on diode's efficacy and colour point. A hybrid dimming strategy has been...

  12. Examining Young Recreational Male Soccer Players' Experience in Adult- and Peer-Led Structures

    Science.gov (United States)

    Imtiaz, Faizan; Hancock, David J.; Côté, Jean

    2016-01-01

    Purpose: Youth sport has the potential to be one of the healthiest and most beneficial activities in which children can partake. Participation in a combination of adult-led and peer-led sport structures appears to lead to favorable outcomes such as enhanced physical fitness, as well as social and emotional development. The purpose of the present…

  13. Project-Based Learning with an Online Peer Assessment System in a Photonics Instruction for Enhancing LED Design Skills

    Science.gov (United States)

    Chang, Shu-Hsuan; Wu, Tsung-Chih; Kuo, Yen-Kuang; You, Li-Chih

    2012-01-01

    This study proposed a novel instructional approach, a two-stage LED simulation of Project-based learning (PBL) course with online peer assessment (OPA), and explored how to apply OPA to the different structured problems in a PBL course to enhance students' professional skills in LED design as well as meta-cognitive thinking. The participants of…

  14. Design and Fabrication of Multi Quantum well based GaN/InGaN Blue LED

    Science.gov (United States)

    Meel, K.; Mahala, P.; Singh, S.

    2018-03-01

    This paper presents the optimization of the multi-quantum well based Light Emitting Diode (LED) structure. We investigate the electrical and optical properties of the device on several factors like well width, barrier width, the number of quantum wells and then optimize the structure. The device is optimized for a well width and barrier width of 3nm and 6nm respectively, consisting of five quantum wells. Simulations were carried out using Silvaco ATLAS TCAD simulation program (Silvaco International, USA). The optimized structure was grown by MOCVD and fabricated. The I-V characteristic was also measured.

  15. Analysis and Comparison of Magnetic Structures in a Tapped Boost Converter for LED Applications

    DEFF Research Database (Denmark)

    Mira Albert, Maria del Carmen; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    This paper presents an an alysis and comparison of magnetics structures in a tapped boost converter for LED applications. The magnetic structure is a coupled inductor which is analyzed in a conventional wire-wound core as well as in a planar structure for different interleaving winding arrangements...

  16. Growth of monolithic full-color GaN-based LED with intermediate carrier blocking layers

    International Nuclear Information System (INIS)

    El-Ghoroury, Hussein S.; Yeh, Milton; Chen, J. C.; Li, X.; Chuang, Chih-Li

    2016-01-01

    Specially designed intermediate carrier blocking layers (ICBLs) in multi-active regions of III-nitride LEDs were shown to be effective in controlling the carrier injection distribution across the active regions. In principle, the majority of carriers, both holes and electrons, can be guided into targeted quantum wells and recombine to generate light of specific wavelengths at controlled current-densities. Accordingly we proposed and demonstrated a novel monolithic InGaN-based LED to achieve three primary colors of light from one device at selected current densities. This LED structure, which has three different sets of quantum wells separated with ICBLs for three primary red-green-blue (RGB) colors, was grown by metal-organic chemical vapor deposition (MOCVD). Results show that this LED can emit light ranging from 460 to 650 nm to cover the entire visible spectrum. The emission wavelength starts at 650 nm and then decreases to 460 nm or lower as the injection current increases. In addition to three primary colors, many other colors can be obtained by color mixing techniques. To the best of our knowledge, this is the first demonstration of monolithic full-color LED grown by a simple growth technique without using re-growth process.

  17. Differences in the structure of outpatient diabetes care between endocrinologist-led and general physician-led services.

    LENUS (Irish Health Repository)

    O Donnell, Máire

    2013-11-25

    Despite a shift in diabetes care internationally from secondary to primary care, diabetes care in the Republic of Ireland remains very hospital-based. Significant variation in the facilities and resources available to hospitals providing outpatient diabetes care have been reported in the UK. The aim of this study was to ascertain the structure of outpatient diabetes care in public hospitals in the Republic of Ireland and whether differences existed in services provided across hospitals.

  18. Output blue light evaluation for phosphor based smart white LED wafer level packages.

    Science.gov (United States)

    Kolahdouz, Zahra; Rostamian, Ali; Kolahdouz, Mohammadreza; Ma, Teng; van Zeijl, Henk; Zhang, Kouchi

    2016-02-22

    This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The maximum responsivity at 480 nm is matched with the target blue LED illumination. The designed structure have better responsivity compared to simple photodiode structure due to reducing the effect of dead layer formation close to the surface because of implantation. It has also a two-fold increase in the responsivity and quantum efficiency compared to previously similar published sensors.

  19. GaN-based LEDs grown by molecular beam epitaxy

    Science.gov (United States)

    Averbeck, Robert; Graber, A.; Tews, H.; Bernklau, D.; Barnhoefer, Ulrich; Riechert, Henning

    1998-04-01

    We report on the growth of GaN, InGaN and GaN/InGaN/GaN pn- junctions grown on sapphire by RF-plasma assisted MBE. MBE allows us to grow high quality nitrides with growth rates around 1 micrometers /h at relatively low temperatures. Thereby p- type doping with Mg and the incorporation of In in InGaN are greatly facilitated. Device-typical n- and p-type doping levels yield room temperature mobilities of 220 cm2/Vs and 10 cm2/Vs, respectively. InGaN with In contents of more than 40 percent is readily achieved. LEDs fabricated from heterostructures with a 4 nm InGaN layer show bright blue or green electroluminescence depending on the In content. Various effects in the electroluminescence caused by fluctuations in the conduction and valence band will be discussed, the most striking one a reduction in linewidth with increasing temperature.

  20. An underwater optical wireless communication system based on LED source

    Science.gov (United States)

    Rao, Jionghui; Wei, Wei; Wang, Feng; Zhang, Xiaohui

    2011-11-01

    Compared with other communication methods, optical wireless communication (OWC) holds the merits of higher transmitting rate and sufficient secrecy. So it is an efficacious communicating measure for data transmitting between underwater carriers. However, due to the water attenuation and the transmitter & the receiver (TX/RX) collimation, this application is restrained in underwater mobile carriers. A prototype for underwater OWC was developed, in which a high-powered green LED array was used as the light source which partly raveled the TX/RX collimation out. A small pumped-multiple-tube (PMT) was used as the detector to increase the communicating range, and FPGA chips were employed to code and decode the communicating data. The data rate of the prototype approached to 4 Mb/s at 8.4m and 1 Mb/s at 22m where voice and Morse communications were achieved in a scope of 30 degree TX/RX angle.

  1. A UV LED-based Charge Management System for LISA

    Science.gov (United States)

    Conklin, John W.; Chilton, Andrew; Olatunde, Taiwo Janet; Apple, Stephen; Parry, Samantha; Ciani, Giacomo; Wass, Peter; Mueller, Guido

    2018-01-01

    The Laser Interferometer Space Antenna (LISA) will be the first space instrument to observe gravitational waves in the millihertz frequency band. LISA consists of three Sun-orbiting spacecraft that form an equilateral triangle, with each side measuring 2.5 million kilometers in length. Each spacecraft houses two free-floating test masses, which are protected from all disturbing forces so that they follow pure geodesics in spacetime. A drag-free control system commands micronewton thrusters to force the spacecraft to fly in formation with the test masses and laser interferometers measure the minute variations in the distance, or light travel time, between these free-falling test masses caused by gravitational waves. The LISA observatory, with a planned launch in the early 2030s, is led by the European Space Agency with significant contributions from NASA. Recently, NASA has initiated strategic investments in key LISA technologies that will likely become U.S. flight hardware contributions to this ground-breaking mission. One of these payload elements is the Charge Management System (CMS), which controls the electric potential of the test masses relative to their housings to reduce spurious force noise acting on the test masses to below the required level. This talk, presented by University of Florida team that leads the CMS development, will describe this vital U.S. contribution to the LISA mission in the context of the envisioned LISA payload architecture and its in-flight sensitivity to gravitational waves.

  2. Strain analysis of InGaN/GaN multi quantum well LED structures

    Energy Technology Data Exchange (ETDEWEB)

    Sebnem Cetin, S.; Kemal Oeztuerk, M.; Oezcelik, S. [Department of Physics, Science Faculty, Gazi University, Ankara (Turkey); Photonics Application and Research Center, Gazi University, Ankara (Turkey); Oezbay, E. [Nanotechnology Research Center, Department of Physics, Department of Electrical and Electronics Engineering, Bilkent, Ankara (Turkey)

    2012-08-15

    Five period InGaN/GaN multi quantum well (MQW) light emitting diode (LED) structures were grown by a metalorganic chemical vapor deposition (MOCVD) system on c-plane sapphire. The structural characteristics as a strain-stress analysis of hexagonal epilayers MQWs were determined by using nondestructive high resolution x-ray diffraction (HRXRD) in detail. The strain/stress analysis in AlN, GaN, and InGaN thin films with a variation of the In molar fraction in the InGaN well layers was conducted based on the precise measurement of the lattice parameters. The a- and c-lattice parameters of the structures were calculated from the peak positions obtained by rocking the theta axis at the vicinity of the symmetric and asymmetric plane reflection angles, followed by the in-plane and out-of-plane strains. The biaxial and hydrostatic components of the strain were extracted from the obtained a- and c-direction strains values. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Nurse-Led School-Based Child Obesity Prevention

    Science.gov (United States)

    Tucker, Sharon; Lanningham-Foster, Lorraine M.

    2015-01-01

    School-based childhood obesity prevention programs have grown in response to reductions in child physical activity (PA), increased sedentariness, poor diet, and soaring child obesity rates. Multiple systematic reviews indicate school-based obesity prevention/treatment interventions are effective, yet few studies have examined the school nurse role…

  4. Grid converter for LED based intelligent light sources

    DEFF Research Database (Denmark)

    Török, Lajos

    to reduce the size of the magnetic components. A description of different grid regulations was given followed by a set of converter topologies and controllers. Different control techniques were pointed out. Among the listed topologies and control solutions few were selected for further analysis, design...... controllers can be designed. The controller design was interconnected with the hardware design and control platform. Thus two dfferent prototypes were designed and built with two dierent digital controllers and the controller design, analysis and implementation was based on these two case studies. The first...... of the PI controller. All four control loops were implemented in a 16 bitfixed point dsPIC33FJ32GS406 microcontroller driving at the same time 8 PWM channels. Finally a brief analysis was done on the eect of the grid disturbances, especially voltage sags on the digital controller. Dierent grid codes...

  5. Development of Advanced LED Phosphors by Spray-based Processes for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Cabot Corporation

    2007-09-30

    The overarching goal of the project was to develop luminescent materials using aerosol processes for making improved LED devices for solid state lighting. In essence this means improving white light emitting phosphor based LEDs by improvement of the phosphor and phosphor layer. The structure of these types of light sources, displayed in Figure 1, comprises of a blue or UV LED under a phosphor layer that converts the blue or UV light to a broad visible (white) light. Traditionally, this is done with a blue emitting diode combined with a blue absorbing, broadly yellow emitting phosphor such as Y{sub 3}Al{sub 5}O{sub 12}:Ce (YAG). A similar result may be achieved by combining a UV emitting diode and at least three different UV absorbing phosphors: red, green, and blue emitting. These emitted colors mix to make white light. The efficiency of these LEDs is based on the combined efficiency of the LED, phosphor, and the interaction between the two. The Cabot SSL project attempted to improve the over all efficiency of the LED light source be improving the efficiency of the phosphor and the interaction between the LED light and the phosphor. Cabot's spray based process for producing phosphor powders is able to improve the brightness of the powder itself by increasing the activator (the species that emits the light) concentration without adverse quenching effects compared to conventional synthesis. This will allow less phosphor powder to be used, and will decrease the cost of the light source; thus lowering the barrier of entry to the lighting market. Cabot's process also allows for chemical flexibility of the phosphor particles, which may result in tunable emission spectra and so light sources with improved color rendering. Another benefit of Cabot's process is the resulting spherical morphology of the particles. Less light scattering results when spherical particles are used in the phosphor layer (Figure 1) compared to when conventional, irregular shaped

  6. Photoelectric diagnostics of InGaN-based LEDs in static and dynamic modes

    Science.gov (United States)

    Radaev, O. A.; Frolov, I. V.; Sergeev, V. A.

    2017-11-01

    The method and measuring installation for diagnostics of light-emitting heterostructures (HS) with the quantum well (QW) by registration of the photocurrent arising in case of radiation of HS the narrow-band optical radiation of different wavelength in the static and dynamic modes are described. On the example of commercial InGaN-based LEDs it is shown that offset of a maximum of photocurrent spectrum concerning a maximum of electroluminescence spectrum is defined by QW depth. The steepness of photocurrent spectrum on the section corresponding to absorption in QW is defined by structural perfection of heteroboundaries. In case of harmonic modulation of a luminous flux on all probed wave-lengths amplitude of a photocurrent of blue LEDs monotonically falls down with growth of modulation frequency with the steepness 0,2 dB for a decade, and at green LEDs to the frequency of 200 kHz the plateau and then recession with the steepness 8 dB for a decade is watched.

  7. Design for The Indoor Visible Light Communication Application System Based on LED Visible Light

    Directory of Open Access Journals (Sweden)

    Lian Wenyu

    2017-01-01

    Full Text Available This paper designs an indoor visible light communication application system based on LED. The system can modulate the original signal one or more times, move to a specific frequency band, transmit on the power line, in the LED terminal use this module to decode, restore the Ethernet signals. This design is applicable to the simplicity of the LED visible light communication applications, which provide the premise and guarantee for the construction of smart home network.

  8. Enhanced light extraction from GaN-based LEDs with a bottom-up assembled photonic crystal

    International Nuclear Information System (INIS)

    Gong Haibo; Hao Xiaopeng; Wu Yongzhong; Cao Bingqiang; Xia Wei; Xu Xiangang

    2011-01-01

    Highlights: → Polystyrene (PS) microspheres were employed as a template. → A noninvasive photonic crystal was fabricated on the surface of GaN-based LED. → Periodic arrangement of bowl-like holes served as a photonic crystal with gradually changed fill factors. → The electroluminescence intensity of LED with a photonic crystal was significantly enhanced. - Abstract: Photonic crystal (PhC) structure is an efficient tool for light extraction from light-emitting diodes (LEDs). The fabrication of a large area PhC structure on the light output surface of LEDs often involves sophisticated equipments such as nanoimprint lithography machine. In this study a monolayer of polystyrene (PS) microspheres was employed as a template to fabricate a noninvasive photonic crystal of indium tin oxide (ITO) on the surface of GaN-based LED. PS spheres can help to form periodic arrangement of bowl-like holes, a photonic crystal with gradually changed fill factors. Importantly, the electroluminescence intensity of LED with a photonic crystal was significantly enhanced by 1.5 times compared to that of the conventional one under various forward injection currents.

  9. Enhanced light extraction from GaN-based LEDs with a bottom-up assembled photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Gong Haibo [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); School of Materials Science and Engineering, University of Jinan, Jinan, 250022 (China); Hao Xiaopeng, E-mail: xphao@sdu.edu.cn [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); Wu Yongzhong [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); Cao Bingqiang [School of Materials Science and Engineering, University of Jinan, Jinan, 250022 (China); Xia Wei [Shandong Huaguang Optoelectronics Company, Ltd., Jinan, 250101 (China); Xu Xiangang [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); Shandong Huaguang Optoelectronics Company, Ltd., Jinan, 250101 (China)

    2011-08-15

    Highlights: > Polystyrene (PS) microspheres were employed as a template. > A noninvasive photonic crystal was fabricated on the surface of GaN-based LED. > Periodic arrangement of bowl-like holes served as a photonic crystal with gradually changed fill factors. > The electroluminescence intensity of LED with a photonic crystal was significantly enhanced. - Abstract: Photonic crystal (PhC) structure is an efficient tool for light extraction from light-emitting diodes (LEDs). The fabrication of a large area PhC structure on the light output surface of LEDs often involves sophisticated equipments such as nanoimprint lithography machine. In this study a monolayer of polystyrene (PS) microspheres was employed as a template to fabricate a noninvasive photonic crystal of indium tin oxide (ITO) on the surface of GaN-based LED. PS spheres can help to form periodic arrangement of bowl-like holes, a photonic crystal with gradually changed fill factors. Importantly, the electroluminescence intensity of LED with a photonic crystal was significantly enhanced by 1.5 times compared to that of the conventional one under various forward injection currents.

  10. Glare effect for three types of street lamps based on White LEDs

    Science.gov (United States)

    Sun, Ching-Cherng; Jiang, Chong-Jhih; Chen, Yi-Chun; Yang, Tsung-Hsun

    2014-05-01

    This study is aimed to assess the glare effect from LED-based street lamps with three general optical designs, which are cluster LEDs with a single lens, a LED array accompany with a lens array, and a tilted LED array, respectively. Observation conditions were simulated based on various locations and viewing axes. Equivalent luminance calculations were used to reveal the glare levels of the three designs. The age effect for the calculated equivalent luminance was also examined for human eyes of people at the age of 40 or 60. The results demonstrate that among the three design types, a LED array accompany with a lens array causes relatively smaller glare for most viewing conditions.

  11. DMD-based LED-illumination Super-resolution and optical sectioning microscopy

    Science.gov (United States)

    Dan, Dan; Lei, Ming; Yao, Baoli; Wang, Wen; Winterhalder, Martin; Zumbusch, Andreas; Qi, Yujiao; Xia, Liang; Yan, Shaohui; Yang, Yanlong; Gao, Peng; Ye, Tong; Zhao, Wei

    2013-01-01

    Super-resolution three-dimensional (3D) optical microscopy has incomparable advantages over other high-resolution microscopic technologies, such as electron microscopy and atomic force microscopy, in the study of biological molecules, pathways and events in live cells and tissues. We present a novel approach of structured illumination microscopy (SIM) by using a digital micromirror device (DMD) for fringe projection and a low-coherence LED light for illumination. The lateral resolution of 90 nm and the optical sectioning depth of 120 μm were achieved. The maximum acquisition speed for 3D imaging in the optical sectioning mode was 1.6×107 pixels/second, which was mainly limited by the sensitivity and speed of the CCD camera. In contrast to other SIM techniques, the DMD-based LED-illumination SIM is cost-effective, ease of multi-wavelength switchable and speckle-noise-free. The 2D super-resolution and 3D optical sectioning modalities can be easily switched and applied to either fluorescent or non-fluorescent specimens. PMID:23346373

  12. Forward Conduction Mode Controlled Piezoelectric Transformer-Based PFC LED Drive

    DEFF Research Database (Denmark)

    Roedgaard, M. S.; Weirich, M.; Andersen, M. A. E.

    2013-01-01

    priced market. In this paper, a new forward conduction mode (FCM) control method for piezoelectric transformer (PT)-based power converters is proposed. A PT-based LED drive facilitating passive PFC is developed, utilizing and validating the FCM control method. The drive utilizes an inductorless half...... LED drive has been developed, supplied from 230-V 50-Hz ac mains, achieving a power factor of 0.96....

  13. Implementation and Test of a LED-Based Lamp for a Lighthouse

    Directory of Open Access Journals (Sweden)

    Luca Mercatelli

    2014-01-01

    Full Text Available A novel sustainable source was developed for an existing Italian lighthouse, exploiting the light emitting diode (LED technology and the norms evolution. The research work started with the optical design of the device, while this work concerns the realization, installation, and test of the new LED lamp. The lamp recombines multiple separated LEDs, realizing a quasipunctual localized source. After installation in the lighthouse, specific photometric tests verified that the proposed power-saving source satisfied the illumination requirements of the marine signaling norms. The advantages of the LED-based lamp are reduced energy consumption, enhanced efficiency, longer life, decreased faults, slower aging, and lower maintenance costs. The obtained LED signalling device is more durable and reliable. In the future the application of these power-saving long-life sources could be extended to other maritime signaling devices or to other traffic signs.

  14. Precise Temperature Mapping of GaN-Based LEDs by Quantitative Infrared Micro-Thermography

    Directory of Open Access Journals (Sweden)

    Geon Hee Kim

    2012-04-01

    Full Text Available A method of measuring the precise temperature distribution of GaN-based light-emitting diodes (LEDs by quantitative infrared micro-thermography is reported. To reduce the calibration error, the same measuring conditions were used for both calibration and thermal imaging; calibration was conducted on a highly emissive black-painted area on a dummy sapphire wafer loaded near the LED wafer on a thermoelectric cooler mount. We used infrared thermal radiation images of the black-painted area on the dummy wafer and an unbiased LED wafer at two different temperatures to determine the factors that degrade the accuracy of temperature measurement, i.e., the non-uniform response of the instrument, superimposed offset radiation, reflected radiation, and emissivity map of the LED surface. By correcting these factors from the measured infrared thermal radiation images of biased LEDs, we determined a precise absolute temperature image. Consequently, we could observe from where the local self-heat emerges and how it distributes on the emitting area of the LEDs. The experimental results demonstrated that highly localized self-heating and a remarkable temperature gradient, which are detrimental to LED performance and reliability, arise near the p-contact edge of the LED surface at high injection levels owing to the current crowding effect.

  15. Precise Temperature Mapping of GaN-Based LEDs by Quantitative Infrared Micro-Thermography

    Science.gov (United States)

    Chang, Ki Soo; Yang, Sun Choel; Kim, Jae-Young; Kook, Myung Ho; Ryu, Seon Young; Choi, Hae Young; Kim, Geon Hee

    2012-01-01

    A method of measuring the precise temperature distribution of GaN-based light-emitting diodes (LEDs) by quantitative infrared micro-thermography is reported. To reduce the calibration error, the same measuring conditions were used for both calibration and thermal imaging; calibration was conducted on a highly emissive black-painted area on a dummy sapphire wafer loaded near the LED wafer on a thermoelectric cooler mount. We used infrared thermal radiation images of the black-painted area on the dummy wafer and an unbiased LED wafer at two different temperatures to determine the factors that degrade the accuracy of temperature measurement, i.e., the non-uniform response of the instrument, superimposed offset radiation, reflected radiation, and emissivity map of the LED surface. By correcting these factors from the measured infrared thermal radiation images of biased LEDs, we determined a precise absolute temperature image. Consequently, we could observe from where the local self-heat emerges and how it distributes on the emitting area of the LEDs. The experimental results demonstrated that highly localized self-heating and a remarkable temperature gradient, which are detrimental to LED performance and reliability, arise near the p-contact edge of the LED surface at high injection levels owing to the current crowding effect. PMID:22666050

  16. Design of the control system for full-color LED display based on MSP430 MCU

    Science.gov (United States)

    Li, Xue; Xu, Hui-juan; Qin, Ling-ling; Zheng, Long-jiang

    2013-08-01

    The LED display incorporate the micro electronic technique, computer technology and information processing as a whole, it becomes the most preponderant of a new generation of display media with the advantages of bright in color, high dynamic range, high brightness and long operating life, etc. The LED display has been widely used in the bank, securities trading, highway signs, airport and advertising, etc. According to the display color, the LED display screen is divided into monochrome screen, double color display and full color display. With the diversification of the LED display's color and the ceaseless rise of the display demands, the LED display's drive circuit and control technology also get the corresponding progress and development. The earliest monochrome screen just displaying Chinese characters, simple character or digital, so the requirements of the controller are relatively low. With the widely used of the double color LED display, the performance of its controller will also increase. In recent years, the full color LED display with three primary colors of red, green, blue and grayscale display effect has been highly attention with its rich and colorful display effect. Every true color pixel includes three son pixels of red, green, blue, using the space colour mixture to realize the multicolor. The dynamic scanning control system of LED full-color display is designed based on MSP430 microcontroller technology of the low power consumption. The gray control technology of this system used the new method of pulse width modulation (PWM) and 19 games show principle are combining. This method in meet 256 level grayscale display conditions, improves the efficiency of the LED light device, and enhances the administrative levels feels of the image. Drive circuit used 1/8 scanning constant current drive mode, and make full use of the single chip microcomputer I/O mouth resources to complete the control. The system supports text, pictures display of 256 grayscale

  17. In-situ metrology in multiwafer reactors during MOVPE of AIN-based UV-LEDs (Conference Presentation)

    Science.gov (United States)

    Knauer, Arne; Brunner, Frank; Kolbe, Tim; Hagedorn, Sylvia; Kueller, Viola; Weyers, Markus

    2017-02-01

    UV-LEDs are of great interest for applications like disinfection, gas sensing, and phototherapy. The cost sensitive LEDs are commonly grown by MOVPE on transparent AlN/sapphire templates. The large thermal and lattice mismatch between AlN and sapphire generates a very high dislocation density (DD) and causes big challenges in strain management. The threading dislocation density should be reduced to the order of low 108cm-2 for high internal efficiency of the AlGaN based UV-LED structures. The TDD will be reduced mainly by dislocation annihilation during the growth of thick Al(Ga)N layers, which is a challenge in terms of strain management. We present how in-situ reflectometry and curvature measurement (EpiCurveTT(at)LayTec) in commercial multiwafer growth reactors helps to optimize the growth processes concerning growth rates, surface roughening and avoidance of layer cracking on 2inch substrates and enhance the reproducibility of epitaxial growth. The growth of up to 3 μm thick planar AlN templates and up-to 10 μm thick AlN/sapphire templates by epitaxial lateral overgrowth of stripe patterned templates for UV-C LED structures will be highlighted. The implementation of different types of AlN/GaN superlattices for the subsequent growth of up to 5μm thick Al0.5Ga0.5N layer for UVB LED structures will be shown. Correlations to ex-situ measurements like X-ray diffraction and TEM analysis of defects in the LED structures will be shown. Some challenges of in-situ control through very narrow viewports as in Close Coupled Showerhead reactors will be discussed as well as the influence of silicon doping on curvature and dislocation density in Al(Ga)N layers.

  18. Energy-Saving Tunnel Illumination System Based on LED's Intelligent Control

    International Nuclear Information System (INIS)

    Guo Shanshan; Wu Lan; Gu Hanting; Jiang Shuixiu

    2011-01-01

    At present there is a lot of electric energy wastage in tunnel illumination, whose design is based on the maximum brightness outside and the maximum vehicle speed all year round. LED's energy consumption is low, and the control of its brightness is simple and effective. It can be quickly adjusted between 0-100% of its maximum brightness, and will not affect the service life. Therefore, using LED as tunnel's illumination source, we can achieve a good energy saving effect. According to real-time data acquisition of vehicle speed, traffic flow and brightness outside the tunnel, the auto real-time control of tunnel illumination can be achieved. And the system regulated the LED luminance by means of combination of LED power module and intelligent control module. The tunnel information was detected by inspection equipments, which included luminometer, vehicle detector, and received by RTU(Remote Terminal Unit), then synchronously transmitted to PC. After data processing, RTU emitted the dimming signal to the LED driver to adjust the brightness of LED. Despite the relatively high cost of high-power LED lights, the enormous energy-saving effect and the well-behaved controllability is beyond compare to other lighting devices.

  19. Design and radiation tests on a LED based emergency evacuation directional lighting

    CERN Document Server

    Trikoupis, Nikolaos

    2017-01-01

    A LED (Light Emitting Diode) based directional lighting system has been designed to indicate the best evacuation direction for applications like the Large Hadron Collider (LHC) tunnel. The design includes constraints for redundancy required by safety systems and for components selection by radiation effects. Most of the literature for radiation effects on LEDs concern digital communications systems, although some recent reports do exist for visible spectrum power LEDs and the reduction in light output versus dose is coherent with the results presented in this paper. Prototype lighting units were irradiated in CERN’s CHARM facility up to a Total Integrated Dose (TID) of 870 Gy and no failures were observed. This paper describes the basic design, presents field tests and the effects of radiation on the LEDs luminance.

  20. Efficiency and Droop Improvement in GaN-Based High-Voltage Flip Chip LEDs

    Directory of Open Access Journals (Sweden)

    Yen-Chih Chiang

    2014-01-01

    Full Text Available The GaN-based high-voltage flip chip light-emitting diode (HVFC-LED is designed and developed for the purpose of efficiency enhancement. In our design, the distributed Bragg reflector (DBR is deposited at the bonded substrate to increase the light extraction. After the flip chip process, the general current-voltage characteristics between the flip chip sample and the traditional sample are essentially the same. With the help of great thermal conductive silicon substrate and the bottom DBR, the HVFC-LED is able to enhance the power by 37.1% when compared to the traditional high-voltage LEDs. The wall-plug efficiencies of the HVFC-LED also show good droop reduction as high as 9.9% compared to the traditional devices.

  1. Visible light communication based vehicle positioning using LED street light and rolling shutter CMOS sensors

    Science.gov (United States)

    Do, Trong Hop; Yoo, Myungsik

    2018-01-01

    This paper proposes a vehicle positioning system using LED street lights and two rolling shutter CMOS sensor cameras. In this system, identification codes for the LED street lights are transmitted to camera-equipped vehicles through a visible light communication (VLC) channel. Given that the camera parameters are known, the positions of the vehicles are determined based on the geometric relationship between the coordinates of the LEDs in the images and their real world coordinates, which are obtained through the LED identification codes. The main contributions of the paper are twofold. First, the collinear arrangement of the LED street lights makes traditional camera-based positioning algorithms fail to determine the position of the vehicles. In this paper, an algorithm is proposed to fuse data received from the two cameras attached to the vehicles in order to solve the collinearity problem of the LEDs. Second, the rolling shutter mechanism of the CMOS sensors combined with the movement of the vehicles creates image artifacts that may severely degrade the positioning accuracy. This paper also proposes a method to compensate for the rolling shutter artifact, and a high positioning accuracy can be achieved even when the vehicle is moving at high speeds. The performance of the proposed positioning system corresponding to different system parameters is examined by conducting Matlab simulations. Small-scale experiments are also conducted to study the performance of the proposed algorithm in real applications.

  2. Quantification and analysis of color stability based on thermal transient behavior in white LED lamps.

    Science.gov (United States)

    Nisa Khan, M

    2017-09-20

    We present measurement and analysis of color stability over time for two categories of white LED lamps based on their thermal management scheme, which also affects their transient lumen depreciation. We previously reported that lumen depreciation in LED lamps can be minimized by properly designing the heat sink configuration that allows lamps to reach a thermal equilibrium condition quickly. Although it is well known that lumen depreciation degrades color stability of white light since color coordinates vary with total lumen power by definition, quantification and characterization of color shifts based on thermal transient behavior have not been previously reported in literature for LED lamps. Here we provide experimental data and analysis of transient color shifts for two categories of household LED lamps (from a total of six lamps in two categories) and demonstrate that reaching thermal equilibrium more quickly provides better stability for color rendering, color temperature, and less deviation of color coordinates from the Planckian blackbody locus line, which are all very important characterization parameters of color for white light. We report for the first time that a lamp's color degradation from the turn-on time primarily depends on thermal transient behavior of the semiconductor LED chip, which experiences a wavelength shift as well as a decrease in its dominant wavelength peak value with time, which in turn degrades the phosphor conversion. For the first time, we also provide a comprehensive quantitative analysis that differentiates color degradation due to the heat rise in GaN/GaInN LED chips and subsequently the boards these chips are mounted on-from that caused by phosphor heating in a white LED module. Finally, we briefly discuss why there are some inevitable trade-offs between omnidirectionality and color and luminous output stability in current household LED lamps and what will help eliminate these trade-offs in future lamp designs.

  3. Parent Interest in a School-Based, School Nurse-Led Weight Management Program

    Science.gov (United States)

    Kubik, Martha Y.; Lee, Jiwoo

    2014-01-01

    Because one in three children is already overweight or obese, school-based interventions targeting secondary obesity prevention merit consideration. This study assessed parent interest in participating in a school-based, school nurse-led weight management program for young school-aged children. A random sample of parents ("n" = 122) of…

  4. Clinician-led, peer-led, and internet-delivered dissonance-based eating disorder prevention programs: Acute effectiveness of these delivery modalities.

    Science.gov (United States)

    Stice, Eric; Rohde, Paul; Shaw, Heather; Gau, Jeff M

    2017-09-01

    Because independent trials have provided evidence for the efficacy and effectiveness of the dissonance-based Body Project eating disorder prevention program, the present trial tested whether clinicians produce the largest intervention effects, or whether delivery can be task-shifted to less expensive undergraduate peer educators or to Internet delivery without effect size attenuation, focusing on acute effects. In this study, 680 young women (M age = 22.2 years, SD = 7.1) recruited at colleges in 2 states were randomized to clinician-led Body Project groups, peer-led Body Project groups, the Internet-based eBody Project, or an educational video control condition. Participants in all 3 variants of the Body Project intervention showed significantly greater reductions in eating disorder risk factors and symptoms than did educational video controls. Participants in clinician-led and peer-led Body Project groups showed significantly greater reductions in risk factors than did eBody Project participants, but effects for the 2 types of groups were similar. Eating disorder onset over 7-month follow-up was significantly lower for peer-led Body Project group participants versus eBody Project participants (2.2% vs. 8.4%) but did not differ significantly between other conditions. The evidence that all 3 dissonance-based prevention programs outperformed an educational video condition, that both group-based interventions outperformed the Internet-based intervention in risk factor reductions, and that the peer-led groups showed lower eating disorder onset over follow-up than did the Internet-based intervention is novel. These acute-effects data suggest that both group-based interventions produce superior eating disorder prevention effects than does the Internet-based intervention and that delivery can be task-shifted to peer leaders. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  5. Air Base Wing and Air Mobility Wing Consolidating on AMC-LED Joint Bases: A Delphi Study

    Science.gov (United States)

    2014-06-13

    AIR BASE WING AND AIR MOBILITY WING CONSOLIDATION ON AMC-LED JOINT BASES: A DELPHI STUDY GRADUATE RESEARCH PAPER Mason E. MacGarvey... DELPHI STUDY GRADUATE RESEARCH PAPER Presented to the Faculty Graduate School of Engineering Management Air Force Institute of Technology...iv AIR BASE WING AND AIR MOBILITY WING CONSOLIDATION ON AMC-LED JOINT BASES: A DELPHI STUDY Mason E. MacGarvey, BS, MBA

  6. Prognostics-based qualification of high-power white LEDs using Lévy process approach

    Science.gov (United States)

    Yung, Kam-Chuen; Sun, Bo; Jiang, Xiaopeng

    2017-01-01

    Due to their versatility in a variety of applications and the growing market demand, high-power white light-emitting diodes (LEDs) have attracted considerable attention. Reliability qualification testing is an essential part of the product development process to ensure the reliability of a new LED product before its release. However, the widely used IES-TM-21 method does not provide comprehensive reliability information. For more accurate and effective qualification, this paper presents a novel method based on prognostics techniques. Prognostics is an engineering technology predicting the future reliability or determining the remaining useful lifetime (RUL) of a product by assessing the extent of deviation or degradation from its expected normal operating conditions. A Lévy subordinator of a mixed Gamma and compound Poisson process is used to describe the actual degradation process of LEDs characterized by random sporadic small jumps of degradation degree, and the reliability function is derived for qualification with different distribution forms of jump sizes. The IES LM-80 test results reported by different LED vendors are used to develop and validate the qualification methodology. This study will be helpful for LED manufacturers to reduce the total test time and cost required to qualify the reliability of an LED product.

  7. Affording and Constraining Local Moral Orders in Teacher-Led Ability-Based Mathematics Groups

    Science.gov (United States)

    Tait-McCutcheon, Sandi; Shuker, Mary Jane; Higgins, Joanna; Loveridge, Judith

    2015-01-01

    How teachers position themselves and their students can influence the development of afforded or constrained local moral orders in ability-based teacher-led mathematics lessons. Local moral orders are the negotiated discursive practices and interactions of participants in the group. In this article, the developing local moral orders of 12 teachers…

  8. Student-Led Engagement of Journal Article Authors in the Classroom Using Web-Based Videoconferencing

    Science.gov (United States)

    Stockman, Brian J.

    2015-01-01

    The learning environment described here uses Web-based videoconferencing technology to merge the traditional classroom journal article discussion with student-led interviews of journal article authors. Papers that describe recent applications of a given technique are selected, with the author engagement occurring at the end of a three or four week…

  9. Epitaxial Growth of GaN-based LEDs on Simple Sacrificial Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ian Ferguson; Chris Summers

    2009-12-31

    The objective of this project is to produce alternative substrate technologies for GaN-based LEDs by developing an ALD interlayer of Al{sub 2}O{sub 3} on sacrificial substrates such as ZnO and Si. A sacrificial substrate is used for device growth that can easily be removed using a wet chemical etchant leaving only the thin GaN epi-layer. After substrate removal, the GaN LED chip can then be mounted in several different ways to a metal heat sink/reflector and light extraction techniques can then be applied to the chip and compared for performance. Success in this work will lead to high efficiency LED devices with a simple low cost fabrication method and high product yield as stated by DOE goals for its solid state lighting portfolio.

  10. A calibrated UV-LED based light source for water purification and characterisation of photocatalysis.

    Science.gov (United States)

    Sergejevs, A; Clarke, C T; Allsopp, D W E; Marugan, J; Jaroenworaluck, A; Singhapong, W; Manpetch, P; Timmers, R; Casado, C; Bowen, C R

    2017-11-08

    Photocatalysis has a potential to become a cost effective industrial process for water cleaning. One of the most studied photocatalysts is titanium dioxide which, as a wide band gap semiconductor, requires ultraviolet (UV) light for its photoactivation. This is at the wavelengths where the efficiency of present-day light emitting diodes (LEDs) decreases rapidly, which presents a challenge in the use of UV-LEDs for commercially viable photocatalysis. There is also a need for accurate photocatalysis measurement of remediation rates of water-borne contaminants for determining optimum exposure doses in industrial applications. In response to these challenges, this paper describes a UV-LED based photocatalytic test reactor that provides a calibrated adjustable light source and pre-defined test conditions to remove as many sources of uncertainty in photocatalytic analysis as possible and thereby improve data reliability. The test reactor provides a selectable intensity of up to 1.9 kW m -2 at the photocatalyst surface. The comparability of the results is achieved through the use of pre-calibration and control electronics that minimize the largest sources of uncertainty; most notably variations in the intensity and directionality of the UV light emission of LEDs and in LED device heating.

  11. Study and Implementation of White Power-LED Based Indoor Lighting Application for the Healthcare Sector

    Science.gov (United States)

    Chakraborty, A.; Ganguly, R.

    With the current technological growth in the field of device fabrication, white power-LED's are available for solid state lighting applications. This is a paradigm shift from electrical lighting to electronic lighting. The implemented systems are showing some promise by saving a considerable amount of energy as well as providing a good and acceptable illumination level. However, the `useful life' of such devices is an important parameter. If the proper device is not chosen, the desired reliability and performance will not be obtained. In the present work, different parameters associated with reliability of such LED's are studied. Four different varieties of LED's are put to test the `useful life' as per IESNA LM 79 standard. From the results obtained, the proper LED is chosen for further application. Subsequently, lighting design is done for a hospital waiting room (indoor application) with 24 × 7 lighting requirements for replacement of existing CFLs there. The calculations show that although the initial cost is higher for LED based lighting, yet the savings on energy and replacement of the lamp results in a payback time of less than a year.

  12. Computational thermal analysis of cylindrical fin design parameters and a new methodology for defining fin structure in LED automobile headlamp cooling applications

    International Nuclear Information System (INIS)

    Sökmen, Kemal Furkan; Yürüklü, Emrah; Yamankaradeniz, Nurettin

    2016-01-01

    Highlights: • In the study, cooling of LED headlamps in automotive is investigated. • The study is based on free convection cooling of LED module. • Besides free convection, Monte Carlo model is used as radiation model as well. • A new algorithm is presented for designing optimum fin structure. • Suggested algorithm for optimum design is verified by various simulations. - Abstract: In this study, the effects of fin design, fin material, and free and forced convection on junction temperature in automotive headlamp cooling applications of LED lights are researched by using ANSYS CFX 14 software. Furthermore a new methodology is presented for defining the optimum cylindrical fin structure within the given limits. For measuring the performance of methodology, analyses are carried out for various ambient temperatures (25 °C, 50 °C and 80 °C) and different LED power dissipations (0.5 W, 0.75 W, 1 W and 1.25 W). Then, analyses are repeated at different heat transfer coefficients and different fin materials in order to calculate LED junction temperature in order to see if the fin structure proposed by the methodology is appropriate for staying below the given safety temperature limit. As a result, the suggested method has always proposed proper fin structures with optimum characteristics for given LED designs. As another result, for safe junction temperature ranges, it is seen that for all LED power dissipations, adding aluminum or copper plate behind the printed circuit board at low ambient temperatures is sufficient. Also, as the ambient temperature increases, especially in high powered LED lights, addition of aluminum is not sufficient and fin usage becomes essential. High heat transfer coefficient and using copper fin affect the junction temperature positively.

  13. Nurse led, primary care based antiretroviral treatment versus hospital care: a controlled prospective study in Swaziland

    Directory of Open Access Journals (Sweden)

    Bailey Kerry A

    2010-08-01

    Full Text Available Abstract Background Antiretroviral treatment services delivered in hospital settings in Africa increasingly lack capacity to meet demand and are difficult to access by patients. We evaluate the effectiveness of nurse led primary care based antiretroviral treatment by comparison with usual hospital care in a typical rural sub Saharan African setting. Methods We undertook a prospective, controlled evaluation of planned service change in Lubombo, Swaziland. Clinically stable adults with a CD4 count > 100 and on antiretroviral treatment for at least four weeks at the district hospital were assigned to either nurse led primary care based antiretroviral treatment care or usual hospital care. Assignment depended on the location of the nearest primary care clinic. The main outcome measures were clinic attendance and patient experience. Results Those receiving primary care based treatment were less likely to miss an appointment compared with those continuing to receive hospital care (RR 0·37, p p = 0·001. Those receiving primary care based, nurse led care were more likely to be satisfied in the ability of staff to manage their condition (RR 1·23, p = 0·003. There was no significant difference in loss to follow-up or other health related outcomes in modified intention to treat analysis. Multilevel, multivariable regression identified little inter-cluster variation. Conclusions Clinic attendance and patient experience are better with nurse led primary care based antiretroviral treatment care than with hospital care; health related outcomes appear equally good. This evidence supports efforts of the WHO to scale-up universal access to antiretroviral treatment in sub Saharan Africa.

  14. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials

    Energy Technology Data Exchange (ETDEWEB)

    Magalhães Filho, T.R.; Weig, K.M. [Faculdade de Odontologia, Universidade Federal Fluminense, Rua São Paulo 28, CEP 24020-150 Niterói (Brazil); Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Costa, M.F. [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Werneck, M.M. [Engenharia Elétrica (COPPE), Universidade Federal do Rio de Janeiro, CP 68504, CEP: 21941-972 Rio de Janeiro (Brazil); Barthem, R.B. [Instituto de Física, Universidade Federal do Rio de Janeiro, CP 68528, CEP: 21941-972 Rio de Janeiro (Brazil); Costa Neto, C.A., E-mail: celio@metalmat.ufrj.br [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil)

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8 mm diameter and 2 mm thickness were produced and polymerized by 20 s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. - Highlights: • A resin based composite (RBC) was polymerized by three different Light Emitting Diodes. • Each LED had its beam profile visually, wavelength and power analyzed. • The effective polymerization power (EPP) varied from 28% to 52% of the total beam power. • Wavelength seems to be as relevant as power in the light curing process. • Mechanical properties depend on the simultaneous effect of wavelength and power.

  15. An inexpensive Arduino-based LED stimulator system for vision research.

    Science.gov (United States)

    Teikari, Petteri; Najjar, Raymond P; Malkki, Hemi; Knoblauch, Kenneth; Dumortier, Dominique; Gronfier, Claude; Cooper, Howard M

    2012-11-15

    Light emitting diodes (LEDs) are being used increasingly as light sources in life sciences applications such as in vision research, fluorescence microscopy and in brain-computer interfacing. Here we present an inexpensive but effective visual stimulator based on light emitting diodes (LEDs) and open-source Arduino microcontroller prototyping platform. The main design goal of our system was to use off-the-shelf and open-source components as much as possible, and to reduce design complexity allowing use of the system to end-users without advanced electronics skills. The main core of the system is a USB-connected Arduino microcontroller platform designed initially with a specific emphasis on the ease-of-use creating interactive physical computing environments. The pulse-width modulation (PWM) signal of Arduino was used to drive LEDs allowing linear light intensity control. The visual stimulator was demonstrated in applications such as murine pupillometry, rodent models for cognitive research, and heterochromatic flicker photometry in human psychophysics. These examples illustrate some of the possible applications that can be easily implemented and that are advantageous for students, educational purposes and universities with limited resources. The LED stimulator system was developed as an open-source project. Software interface was developed using Python with simplified examples provided for Matlab and LabVIEW. Source code and hardware information are distributed under the GNU General Public Licence (GPL, version 3). Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials.

    Science.gov (United States)

    Magalhães Filho, T R; Weig, K M; Costa, M F; Werneck, M M; Barthem, R B; Costa Neto, C A

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8mm diameter and 2mm thickness were produced and polymerized by 20s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Key Topics in Producing New Ultraviolet Led and Laser Devices Based on Transparent Semiconductor Zinc Oxide

    International Nuclear Information System (INIS)

    Tuezemen, S.

    2004-01-01

    Recently, it has been introduced that ZnO as II-VI semiconductor is promising various technological applications, especially for optoelectronic short wavelength light emitting devices due to its wide and direct band gap profile. The most important advantage of ZnO over the other currently used wide band gap semiconductors such as GaN is that its nearly 3 times higher exciton binding energy (60 meV), which permits efficient excitonic emission at room temperature and above. As-grown ZnO is normally n-type because of the Zn-rich defects such as zinc interstitials (Zn i ) oxygen vacancies (Vo), natively acting as shallow donors and main source of n-type conductivity in as-grown material. Therefore, making p-type ZnO has been more difficult due to unintentional compensation of possible acceptors by these residual donors. In order to develop electro luminescent and laser devices based on the ultraviolet (UV) exciton emission of ZnO, it will be important to fabricate good p-n junctions. Attempts to observe p-type conductivity in ours and our collaborators' laboratories in USA, either by co-doping with N or tuning O pressure have been first successful achievements, resulting in hole concentrations up to 10 1 9 cm - 3 in reactively sputtered thin layers of ZnO. Moreover, in order to produce ZnO based quantum well lasers similar to the previously introduced n-AlGaAs/GaAs/p-AlGaAs structures; we have attempted to grow Zn 1 -xSn x O thin films to enlarge the band gap energy. An increase up to 170 meV has been observed in Zn 1 -xSn x O thin films and this is enough barrier to be able to trap electron-hole pairs in quantum well structures. As a result, two important key issues; p-type conductivity and enhancement of the band gap energy in order to step forward towards the production of electro luminescent UV LEDs and quantum well lasers have been investigated and will be presented in this study

  18. Improvement of interfacial adhesion in vertical GaN-based LEDs by introducing O2 plasma cleaning and intermediate layers

    International Nuclear Information System (INIS)

    Kim, Sunjung

    2010-01-01

    Interfacial adhesion between an indium tin oxide (ITO)/Ni/Ag/Ni/Au p-electrode, and Au and Ni/Au seeds in vertical GaN-based light emitting diodes (LEDs) was enhanced by O 2 plasma cleaning treatment of the Au surface in the p-electrode. However, AES and REELS analyses of the Au surface in the p-electrode detected surface damage to the p-electrode and photoresist (PR) passivation structure from O 2 plasma cleaning. W/Ni and Al/Ni adhesion layers were introduced in the Au seed to increase interfacial adhesion between Au seed and untreated PR passivation. Forward leakage current as low as 0.91 nA at 2 V was observed for the vertical LED with the Al/Ni/Au seed, for which adhesion strength to O 2 plasma-cleaned Au and untreated PR was 141.2 MPa and 62.8 MPa, respectively.

  19. Development of Key Technologies for White Lighting Based on Light-Emitting Diodes (LEDs)

    Energy Technology Data Exchange (ETDEWEB)

    Werner Goetz; Bill Imler; James Kim; Junko Kobayashi; Andrew Kim; Mike Krames; Rick Mann; Gerd Mueller-Mach; Anneli Munkholm; Jonathan Wierer

    2004-03-31

    This program was organized to focus on materials development issues critical to the acceleration of solid-state lighting, and was split into three major thrust areas: (1) study of dislocation density reduction for GaN grown on sapphire using 'cantilever epitaxy', and the impact of dislocation density on the performance of state-of-the-art high-power LEDs; (2) the evaluation of in situ techniques for monitoring gas phase chemistry and the properties of GaN-based layers during metal-organic vapor phase epitaxy (MOCVD), and (3) feasibility for using semiconductor nanoparticles ('quantum dots') for the down-conversion of blue or ultraviolet light to generate white light. The program included a partnership between Lumileds Lighting (epitaxy and device fabrication for high power LEDs) and Sandia National Laboratories (cantilever epitaxy, gas phase chemistry, and quantum dot synthesis). Key findings included: (1) cantilever epitaxy can provide dislocation density reduction comparable to that of more complicated approaches, but all in one epitaxial growth step; however, further improvements are required to realize significant gains in LED performance at high drive currents, (2) in situ tools can provide detailed knowledge about gas phase chemistry, and can be used to monitor and control epitaxial layer composition and temperature to provide improved yields (e.g., a fivefold increase in color targeting is demonstrated for 540nm LEDs), and (3) quantum efficiency for quantum dots is improved and maintained up to 70% in epoxy thin films, but further work is necessary to increase densification (absorption) and robustness before practical application to LEDs.

  20. Assembling and Using an LED-Based Detector to Monitor Absorbance Changes during Acid-Base Titrations

    Science.gov (United States)

    Santos, Willy G.; Cavalheiro, E´der T. G.

    2015-01-01

    A simple photometric assembly based in an LED as a light source and a photodiode as a detector is proposed in order to follow the absorbance changes as a function of the titrant volume added during the course of acid-base titrations in the presence of a suitable visual indicator. The simplicity and low cost of the electronic device allow the…

  1. Nurse-led action research project for expanding nurses′ role in patient education in Iran: Process, structure, and outcomes

    Directory of Open Access Journals (Sweden)

    Parvaneh Khorasani

    2015-01-01

    Full Text Available Background: Patient education is among the lowest met need of patients in Iran; therefore, expansion of that role can result in greater professional accountability. This study aimed to explain the practical science of the process, structure, and outcomes of a nurse-led action research project to expand the nurses′ role in patient education in Iran. Materials and Methods: This study was part of a participatory action research. Daily communications and monthly joint meetings were held from January 2012 to February 2014 for planning and management. These were based on the research protocol, and the conceptual framework included the Mobilizing for Action through Planning and Partnerships process by means of Leadership for Change skills. Data were produced and gathered through participant observations. Administrative data included project records, official documents, artifacts, news, and reports, which were analyzed through qualitative content analysis. Results: A participatory project was established with three groups of participants organized from both academic and clinical fields. These consisted of a "core research support team," "two steering committees," and community representatives of clients and professionals as "feedback groups." A seven-stage process, named the "Nurse Educators: Al-Zahra Role Expansion Action Research" (NEAREAR process, resulted from the project, in which strategic issues were gradually developed and implemented through 32 action plans and quality improvement cycles of action research. Audits and supervision evaluations showed meaningful changes in capacity building components. Conclusions: A nurse-led ad hoc structure with academic-clinical partnerships and strategic management process was suggested as a possible practical model for expanding nurses′ educational role in similar contexts. Implications and practical science introduced in this action research could also be applicable for top managers and health system

  2. Nurse-led action research project for expanding nurses' role in patient education in Iran: Process, structure, and outcomes.

    Science.gov (United States)

    Khorasani, Parvaneh; Rassouli, Maryam; Parvizy, Soroor; Zagheri-Tafreshi, Mansoureh; Nasr-Esfahani, Mahmood

    2015-01-01

    Patient education is among the lowest met need of patients in Iran; therefore, expansion of that role can result in greater professional accountability. This study aimed to explain the practical science of the process, structure, and outcomes of a nurse-led action research project to expand the nurses' role in patient education in Iran. This study was part of a participatory action research. Daily communications and monthly joint meetings were held from January 2012 to February 2014 for planning and management. These were based on the research protocol, and the conceptual framework included the Mobilizing for Action through Planning and Partnerships process by means of Leadership for Change skills. Data were produced and gathered through participant observations. Administrative data included project records, official documents, artifacts, news, and reports, which were analyzed through qualitative content analysis. A participatory project was established with three groups of participants organized from both academic and clinical fields. These consisted of a "core research support team," "two steering committees," and community representatives of clients and professionals as "feedback groups." A seven-stage process, named the "Nurse Educators: Al-Zahra Role Expansion Action Research" (NEAREAR) process, resulted from the project, in which strategic issues were gradually developed and implemented through 32 action plans and quality improvement cycles of action research. Audits and supervision evaluations showed meaningful changes in capacity building components. A nurse-led ad hoc structure with academic-clinical partnerships and strategic management process was suggested as a possible practical model for expanding nurses' educational role in similar contexts. Implications and practical science introduced in this action research could also be applicable for top managers and health system policy makers in a wider range of practice.

  3. Nurse-led action research project for expanding nurses’ role in patient education in Iran: Process, structure, and outcomes

    Science.gov (United States)

    Khorasani, Parvaneh; Rassouli, Maryam; Parvizy, Soroor; Zagheri-Tafreshi, Mansoureh; Nasr-Esfahani, Mahmood

    2015-01-01

    Background: Patient education is among the lowest met need of patients in Iran; therefore, expansion of that role can result in greater professional accountability. This study aimed to explain the practical science of the process, structure, and outcomes of a nurse-led action research project to expand the nurses’ role in patient education in Iran. Materials and Methods: This study was part of a participatory action research. Daily communications and monthly joint meetings were held from January 2012 to February 2014 for planning and management. These were based on the research protocol, and the conceptual framework included the Mobilizing for Action through Planning and Partnerships process by means of Leadership for Change skills. Data were produced and gathered through participant observations. Administrative data included project records, official documents, artifacts, news, and reports, which were analyzed through qualitative content analysis. Results: A participatory project was established with three groups of participants organized from both academic and clinical fields. These consisted of a “core research support team,” “two steering committees,” and community representatives of clients and professionals as “feedback groups.” A seven-stage process, named the “Nurse Educators: Al-Zahra Role Expansion Action Research” (NEAREAR) process, resulted from the project, in which strategic issues were gradually developed and implemented through 32 action plans and quality improvement cycles of action research. Audits and supervision evaluations showed meaningful changes in capacity building components. Conclusions: A nurse-led ad hoc structure with academic–clinical partnerships and strategic management process was suggested as a possible practical model for expanding nurses’ educational role in similar contexts. Implications and practical science introduced in this action research could also be applicable for top managers and health system

  4. DC Grids for Smart LED-Based Lighting: The EDISON Solution

    Directory of Open Access Journals (Sweden)

    Steffen Thielemans

    2017-09-01

    Full Text Available This paper highlights the benefits and possible drawbacks of a DC-based lighting infrastructure for powering Light Emitting Diode (LED-lamps. It also evaluates the efforts needed for integrating the so called smart lighting and other sensor/actuator based control systems, and compares existing and emerging solutions. It reviews and discusses published work in this field with special focus on the intelligent DC-based infrastructure named EDISON that is primarily dedicated to lighting, but is applicable to building automation in general. The EDISON “PowerLAN” consists of a DC-based infrastructure that offers telecommunication abilities and can be applied to lighting retrofitting scenarios for buildings. Its infrastructure allows simple and efficient powering of DC-oriented devices like LED lamps, sensors and microcontrollers, while offering a wired communication channel. This paper motivates the design choices for organizing DC lighting grids and their associated communication possibilities. It also shows how the EDISON based smart lighting solution is evolving today to include new communication technologies and to further integrate other parts of building management solutions through the OneM2M (Machine to Machine service bus.

  5. Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

    Directory of Open Access Journals (Sweden)

    Marco Calciati

    2014-06-01

    Full Text Available Electroluminescence (EL characterization of InGaN/GaN light-emitting diodes (LEDs, coupled with numerical device models of different sophistication, is routinely adopted not only to establish correlations between device efficiency and structural features, but also to make inferences about the loss mechanisms responsible for LED efficiency droop at high driving currents. The limits of this investigative approach are discussed here in a case study based on a comprehensive set of current- and temperature-dependent EL data from blue LEDs with low and high densities of threading dislocations (TDs. First, the effects limiting the applicability of simpler (closed-form and/or one-dimensional classes of models are addressed, like lateral current crowding, vertical carrier distribution nonuniformity, and interband transition broadening. Then, the major sources of uncertainty affecting state-of-the-art numerical device simulation are reviewed and discussed, including (i the approximations in the transport description through the multi-quantum-well active region, (ii the alternative valence band parametrizations proposed to calculate the spontaneous emission rate, (iii the difficulties in defining the Auger coefficients due to inadequacies in the microscopic quantum well description and the possible presence of extra, non-Auger high-current-density recombination mechanisms and/or Auger-induced leakage. In the case of the present LED structures, the application of three-dimensional numerical-simulation-based analysis to the EL data leads to an explanation of efficiency droop in terms of TD-related and Auger-like nonradiative losses, with a C coefficient in the 10−30 cm6/s range at room temperature, close to the larger theoretical calculations reported so far. However, a study of the combined effects of structural and model uncertainties suggests that the C values thus determined could be overestimated by about an order of magnitude. This preliminary

  6. Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

    Energy Technology Data Exchange (ETDEWEB)

    Calciati, Marco; Vallone, Marco; Zhou, Xiangyu; Ghione, Giovanni [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); Goano, Michele, E-mail: michele.goano@polito.it; Bertazzi, Francesco [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); IEIIT-CNR, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); Meneghini, Matteo; Meneghesso, Gaudenzio; Zanoni, Enrico [Dipartimento di Ingegneria dell' Informazione, Università di Padova, Via Gradenigo 6/B, 35131 Padova (Italy); Bellotti, Enrico [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary' s Street, 02215 Boston, MA (United States); Verzellesi, Giovanni [Dipartimento di Scienze e Metodi dell' Ingegneria, Università di Modena e Reggio Emilia, 42122 Reggio Emilia (Italy); Zhu, Dandan; Humphreys, Colin [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-06-15

    Electroluminescence (EL) characterization of InGaN/GaN light-emitting diodes (LEDs), coupled with numerical device models of different sophistication, is routinely adopted not only to establish correlations between device efficiency and structural features, but also to make inferences about the loss mechanisms responsible for LED efficiency droop at high driving currents. The limits of this investigative approach are discussed here in a case study based on a comprehensive set of current- and temperature-dependent EL data from blue LEDs with low and high densities of threading dislocations (TDs). First, the effects limiting the applicability of simpler (closed-form and/or one-dimensional) classes of models are addressed, like lateral current crowding, vertical carrier distribution nonuniformity, and interband transition broadening. Then, the major sources of uncertainty affecting state-of-the-art numerical device simulation are reviewed and discussed, including (i) the approximations in the transport description through the multi-quantum-well active region, (ii) the alternative valence band parametrizations proposed to calculate the spontaneous emission rate, (iii) the difficulties in defining the Auger coefficients due to inadequacies in the microscopic quantum well description and the possible presence of extra, non-Auger high-current-density recombination mechanisms and/or Auger-induced leakage. In the case of the present LED structures, the application of three-dimensional numerical-simulation-based analysis to the EL data leads to an explanation of efficiency droop in terms of TD-related and Auger-like nonradiative losses, with a C coefficient in the 10{sup −30} cm{sup 6}/s range at room temperature, close to the larger theoretical calculations reported so far. However, a study of the combined effects of structural and model uncertainties suggests that the C values thus determined could be overestimated by about an order of magnitude. This preliminary

  7. Peer-led problem-based learning in interprofessional education of health professions students

    Directory of Open Access Journals (Sweden)

    Michael D. Lehrer

    2015-09-01

    Full Text Available Background: The role of peer teachers in interprofessional education has not been extensively studied. This study is designed to determine if peer-teacher-led problem-based seminars can influence medical and pharmacy students’ perceptions of interprofessional education. Methods: Undergraduate medical and pharmacy students participated in one-hour problem-based learning seminars held over the course of 16 weeks. A case–control study design was used to compare perceptions of interprofessional education between students who participated in seminars and students who did not participate in seminars. The validated Interdisciplinary Education Perception Scale (IEPS was used to assess perceptions of interprofessional education and was distributed to medical and pharmacy students at the conclusion of 16 weeks of seminars. A two-tailed t-test was used to determine significance between groups. A survey was also distributed to all students regarding perceived barriers to involvement in interprofessional education training. Results: In total, 97 students responded to IEPS (62 medical, 35 pharmacy. Data showed significantly higher perception of professional cooperation among medical students (p=0.006 and pharmacy students (p=0.02 who attended interprofessional seminars compared to those who did not attend. One hundred and nine students responded to the survey regarding perceived barriers to interprofessional education, with the two most common barriers being: ‘I am not aware of interprofessional education opportunities’ (61.5% and ‘I do not have time to participate’ (52.3%. Conclusion: Based on this data we believe peer-teacher-led problem-based interprofessional seminars can be used to increase medical and pharmacy students’ perceived need for professional cooperation. Currently, major barriers to interprofessional education involvement are awareness and time commitment. Undergraduate health professions education can incorporate student-led

  8. Peer-led problem-based learning in interprofessional education of health professions students.

    Science.gov (United States)

    Lehrer, Michael D; Murray, Samuel; Benzar, Ruth; Stormont, Ryan; Lightfoot, Megan; Hafertepe, Michael; Welch, Gabrielle; Peters, Nicholas; Maio, Anna

    2015-01-01

    The role of peer teachers in interprofessional education has not been extensively studied. This study is designed to determine if peer-teacher-led problem-based seminars can influence medical and pharmacy students' perceptions of interprofessional education. Undergraduate medical and pharmacy students participated in one-hour problem-based learning seminars held over the course of 16 weeks. A case-control study design was used to compare perceptions of interprofessional education between students who participated in seminars and students who did not participate in seminars. The validated Interdisciplinary Education Perception Scale (IEPS) was used to assess perceptions of interprofessional education and was distributed to medical and pharmacy students at the conclusion of 16 weeks of seminars. A two-tailed t-test was used to determine significance between groups. A survey was also distributed to all students regarding perceived barriers to involvement in interprofessional education training. In total, 97 students responded to IEPS (62 medical, 35 pharmacy). Data showed significantly higher perception of professional cooperation among medical students (p=0.006) and pharmacy students (p=0.02) who attended interprofessional seminars compared to those who did not attend. One hundred and nine students responded to the survey regarding perceived barriers to interprofessional education, with the two most common barriers being: 'I am not aware of interprofessional education opportunities' (61.5%) and 'I do not have time to participate' (52.3%). Based on this data we believe peer-teacher-led problem-based interprofessional seminars can be used to increase medical and pharmacy students' perceived need for professional cooperation. Currently, major barriers to interprofessional education involvement are awareness and time commitment. Undergraduate health professions education can incorporate student-led seminars to improve interprofessional education.

  9. Joint structure in high brightness light emitting diode (HB LED) packages

    International Nuclear Information System (INIS)

    Park, Jin-Woo; Yoon, Young-Bok; Shin, Sang-Hyun; Choi, Sang-Hyun

    2006-01-01

    We present the transmission electron microscopy (TEM) analysis of 1.5 μm-thick Au-20Sn solder joint between a high brightness light emitting diode (HB LED) and a Si heat sink. Due to intermetallic compound formation, global Sn depletion occurred in the thin solder, which raised the melting point of the solder and caused local incompleteness of bonding

  10. Interface and transport properties of GaN/graphene junction in GaN-based LEDs

    International Nuclear Information System (INIS)

    Wang Liancheng; Zhang Yiyun; Liu Zhiqiang; Guo Enqing; Yi Xiaoyan; Wang Junxi; Wang Guohong; Li Xiao; Zhu Hongwei

    2012-01-01

    A normalized circular transmission line method pattern with uniform interface area was developed to obtain contact resistances of p-, u-, n-GaN/graphene contacts (p, u and n represent p-type doped, unintentionally doped and n-type doped, respectively) and N-polar u-, n-GaN/graphene contacts in GaN-based LEDs. The resistances of the graphene/GaN contacts were mainly determined by the work function gap and the carrier concentration in GaN. Annealing caused diffusion of metal atoms and significantly influenced the interface transport properties.

  11. Ambient Light An integrative, LED based interaction concept for different levels of automation

    OpenAIRE

    Dziennus, Marc; Kelsch, Johann; Schieben, Anna

    2016-01-01

    In the present paper an innovative approach for the driver-automation interaction based on visual signals is presented. A 360° LED stripe which is installed in the interior of the car communicates to the driver via his peripheral vision (Ambient light). A consistent, color-coded interaction design in the peripheral field of vision is used to guide the driver’s attention and to support him in different level of automation by providing automation-related information. The HMI concept uses situat...

  12. Large area LED package

    Science.gov (United States)

    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.

  13. Nurse led home-based care for people with HIV/AIDS.

    Science.gov (United States)

    Wood, Elizabeth M; Zani, Babalwa; Esterhuizen, Tonya M; Young, Taryn

    2018-03-27

    Home-based care is used in many countries to increase quality of life and limit hospital stay, particularly where public health services are overburdened. Home-based care objectives for HIV/AIDS can include medical care, delivery of antiretroviral treatment and psychosocial support. This review assesses the effects of home-based nursing on morbidity in people infected with HIV/AIDS. The trials studied are in HIV positive adults and children, regardless of sex or setting and all randomised controlled. Home-based care provided by qualified nurses was compared with hospital or health-facility based treatment. The following electronic databases were searched from January 1980 to March 2015: AIDSearch, CINAHL, Cochrane Register of Controlled Trials, EMBASE, MEDLINE and PsycINFO/LIT, with an updated search in November 2016. Two authors independently screened titles and abstracts from the electronic search based on the study design, interventions and types of participant. For all selected abstracts, full text articles were obtained. The final study selection was determined with use of an eligibility form. Data extraction was performed independently from assessment of risk of bias. The results were analysed by narrative synthesis, in order to be able to obtain relevant effect measures plus 95% confidence intervals. Seven studies met the inclusion criteria. The trial size varied from 37 to 238 participants. Only one trial was conducted in children. Five studies were conducted in the USA and two in China. Four studies looked at home-based adherence support and the rest at providing home-based psychosocial support. Reported adherence to antiretroviral drugs improved with nurse-led home-based care but did not affect viral load. Psychiatric nurse support in those with existing mental health conditions improved mental health and depressive symptoms. Home-based psychological support impacted on HIV stigma, worry and physical functioning and in certain cases depressive symptoms

  14. An Easy to Deploy Street Light Control System Based on Wireless Communication and LED Technology

    Directory of Open Access Journals (Sweden)

    Jesús Villadangos

    2013-05-01

    Full Text Available This paper presents an intelligent streetlight management system based on LED lamps, designed to facilitate its deployment in existing facilities. The proposed approach, which is based on wireless communication technologies, will minimize the cost of investment of traditional wired systems, which always need civil engineering for burying of cable underground and consequently are more expensive than if the connection of the different nodes is made over the air. The deployed solution will be aware of their surrounding’s environmental conditions, a fact that will be approached for the system intelligence in order to learn, and later, apply dynamic rules. The knowledge of real time illumination needs, in terms of instant use of the street in which it is installed, will also feed our system, with the objective of providing tangible solutions to reduce energy consumption according to the contextual needs, an exact calculation of energy consumption and reliable mechanisms for preventive maintenance of facilities.

  15. Portable plant chlorophyll fluorimeter based on blue LED rapid induced technology

    Science.gov (United States)

    Zheng, Yibo; Mi, Ting; Zhang, Lei; Zhao, Jun

    2018-01-01

    Fluorimeter is an effective device for detecting chlorophyll a content in plants. In order to realize real-time nondestructive detection of plant blades, a camera based fluorescence instrument based on two color mirrors has been developed. The blue light LED is used as the excitation light source, and the lens is used for shaping and focusing the excitation light to ensure the excitation intensity and uniform illumination of the light source. The device uses a 45 degree two color mirror to separate the chlorophyll a excited light path and the fluorescence receiving light path. Finally, the fluorescent signal is collected by the silicon photocell, and the signal is processed by the circuit to transmit the digital information to the display. Through the analysis of the experimental data, the device has the advantages of small size, easy to carry, fast induction, etc., and can be widely applied in outdoor teaching and field investigation.

  16. Design of the optical structure of a LED light of airfield used on the taxiway centerline of bend

    Science.gov (United States)

    Ma, Xiaodan; Yang, Jianhong; Li, Lei

    2014-07-01

    Along with the continuous renewal of the light source, LED light source could have been used in the lights of airfield already. LED light source in the application will be more energy efficient. This paper designs the optical structure of the taxiway centerline light,which is used on the bend. Osram LT CPDP - KZ - 4 green LED has been chosen to be the light source.Optical components used in the structure, such as the prism, the lens, the scattering pieces, is designed on the basis of the optical design principles. The optical design principle include the edge-ray etendue conservation, conservation of energy and so on. Then, the structure is drawn and simulated. Completing these steps combines with software, such as ProE, Matlab and TracePro. To test the optical structure with Yuanfang GO-2000 distribution photometer. The test results meet the standards of the civil aviation administration's requirements. In order to further reduce energy consumption, and optimize the components on the premise of meeting the requirements of national standards. The paper reduces the input current from 900mA to 400mA by optimizing the components. The method of optimizing is combining the prism with scattering pieces and optimizing the lens surface. The optical structure of the taxiway centerline lights used on the bend after improving is more efficient and meet the requirements of national standards including chromaticity and light intensity.

  17. A method of LED free-form tilted lens rapid modeling based on scheme language

    Science.gov (United States)

    Dai, Yidan

    2017-10-01

    According to nonimaging optical principle and traditional LED free-form surface lens, a new kind of LED free-form tilted lens was designed. And a method of rapid modeling based on Scheme language was proposed. The mesh division method was applied to obtain the corresponding surface configuration according to the character of the light source and the desired energy distribution on the illumination plane. Then 3D modeling software and the Scheme language programming are used to generate lens model respectively. With the help of optical simulation software, a light source with the size of 1mm*1mm*1mm in volume is used in experiment, and the lateral migration distance of illumination area is 0.5m, in which total one million rays are computed. We could acquire the simulated results of both models. The simulated output result shows that the Scheme language can prevent the model deformation problems caused by the process of the model transfer, and the degree of illumination uniformity is reached to 82%, and the offset angle is 26°. Also, the efficiency of modeling process is greatly increased by using Scheme language.

  18. 1Mbps NLOS solar-blind ultraviolet communication system based on UV-LED array

    Science.gov (United States)

    Sun, Zhaotian; Zhang, Lijun; Li, Ping'an; Qin, Yu; Bai, Tingzhu

    2018-01-01

    We proposed and demonstrated a high data rate ultraviolet communication system based on a 266nm UV LED array with 50mW luminous power. The emitting source is driven by a three outputs constant-current control circuit, whose driving speed is up to 2Mbps. At the receiving side, in order to achieve the amplification for high-speed signal, a two-stage differential preamplifier is designed to make I-V conversion. The voltage-current gain is up to 140dB and bandwidth is 1.9MHz. An experiment is conducted to test the performance of the UV communication system. The effects of elevation angles and transmission distance are analyzed. It is shown that the ultraviolet communication system has high data rate of up to 921.6kbps and bit error rate of less than 10-7 in 150m, which can beat the best record created by UV-LED communication system in terms of the transmission rate.

  19. NO2 measurements in Hong Kong using LED based long path differential optical absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    M. O. Wenig

    2012-05-01

    Full Text Available In this study we present the first long term measurements of atmospheric nitrogen dioxide (NO2 using a LED based Long Path Differential Optical Absorption Spectroscopy (LP-DOAS instrument. This instrument is measuring continuously in Hong Kong since December 2009, first in a setup with a 550 m absorption path and then with a 3820 m path at about 30 m to 50 m above street level. The instrument is using a high power blue light LED with peak intensity at 450 nm coupled into the telescope using a Y-fibre bundle. The LP-DOAS instrument measures NO2 levels in the Kowloon Tong and Mongkok district of Hong Kong and we compare the measurement results to mixing ratios reported by monitoring stations operated by the Hong Kong Environmental Protection Department in that area. Hourly averages of coinciding measurements are in reasonable agreement (R = 0.74. Furthermore, we used the long-term data set to validate the Ozone Monitoring Instrument (OMI NO2 data product. Monthly averaged LP-DOAS and OMI measurements correlate well (R = 0.84 when comparing the data for the OMI overpass time. We analyzed weekly patterns in both data sets and found that the LP-DOAS detects a clear weekly cycle with a reduction on weekends during rush hour peaks, whereas OMI is not able to observe this weekly cycle due to its fix overpass time (13:30–14:30 LT – local time.

  20. Assessment of students’ satisfaction with a student-led team-based learning course

    Directory of Open Access Journals (Sweden)

    Justin W. Bouw

    2015-06-01

    Full Text Available Purpose: To date, no studies in the literature have examined student delivery of team-based learning (TBL modules in the classroom. We aimed to assess student perceptions of a student-led TBL elective. Methods: Third-year pharmacy students were assigned topics in teams and developed learning objectives, a 15-minute mini-lecture, and a TBL application exercise and presented them to student colleagues. Students completed a survey upon completion of the course and participated in a focus group discussion to share their views on learning. Results: The majority of students (n=23/30 agreed that creating TBL modules enhanced their understanding of concepts, improved their self-directed learning skills (n=26/30, and improved their comprehension of TBL pedagogy (n=27/30. However, 60% disagreed with incorporating student-generated TBL modules into core curricular classes. Focus group data identified student-perceived barriers to success in the elective, in particular the development of TBL application exercises. Conclusion: This study provides evidence that students positively perceived student-led TBL as encouraging proactive learning from peer-to-peer teaching.

  1. OFDM-based broadband underwater wireless optical communication system using a compact blue LED

    Science.gov (United States)

    Xu, Jing; Kong, Meiwei; Lin, Aobo; Song, Yuhang; Yu, Xiangyu; Qu, Fengzhong; Han, Jun; Deng, Ning

    2016-06-01

    We propose and experimentally demonstrate an IM/DD-OFDM-based underwater wireless optical communication system. We investigate the dependence of its BER performance on the training symbol number as well as LED's bias voltage and driving voltage. With single compact blue LED and a low-cost PIN photodiode, we achieve net bit rates of 225.90 Mb/s at a BER of 1.54×10-3 using 16-QAM and 231.95 Mb/s at a BER of 3.28×10-3 using 32-QAM, respectively, over a 2-m air channel. Over a 2-m underwater channel, we achieve net bit rates of 161.36 Mb/s using 16-QAM, 156.31 Mb/s using 32-QAM, and 127.07 Mb/s using 64-QAM, respectively. The corresponding BERs are 2.5×10-3, 7.42×10-4, and 3.17×10-3, respectively, which are all below the FEC threshold.

  2. Development of LEDs-based microplate reader for bioanalytical assay measurements

    Science.gov (United States)

    Alaruri, Sami D.; Katzlinger, Michael; Schinwald, Bernhard; Kronberger, Georg; Atzler, Joseph

    2013-10-01

    The optical design for an LEDs-based microplate reader that can perform fluorescence intensity (top and bottom), absorbance, luminescence and time-resolved fluorescence measurements is described. The microplate reader is the first microplate reader in the marketplace that incorporates LEDs as excitation light sources. Absorbance measurements over the 0-3.5 optical density range for caffeine solution are presented. Additionally, fluorescence intensity readings collected at 535 and 625 nm from a green and a red RediPlateTM are reported. Furthermore, fluorescence decay lifetime measurements obtained for Eu (europium) and Sm (samarium) standard solutions using 370 nm excitation are presented. The microplate reader detection limits for the fluorescence intensity top, fluorescence intensity bottom, fluorescence polarization and time-resolved fluorescence modes are 1.5 fmol 100 µL-1 fluorescein (384-well plate), 25 fmol 100 µL-1 fluorescein (384-well plate), 5 mP at 10 nM fluorescein (black 384-well plate) and 30 amol 100 µL-1 europium solution (white 384-well plate), respectively.

  3. Student-led tutorials in problem-based learning: educational outcomes and students' perceptions.

    Science.gov (United States)

    Kassab, Salah; Abu-Hijleh, Marwan F; Al-Shboul, Qasim; Hamdy, Hossam

    2005-09-01

    The aim of this study was to examine the effectiveness of using students as tutors in a problem-based learning (PBL) medical curriculum. Ninety-one third-year medical students were divided into ten tutorial groups. The groups were randomly allocated into student-led tutorials (SLT) (five groups, n = 44 students) and faculty-led tutorials (FLT) (five groups, n = 47 students). Outcome measurements included assessment of students' performance in tutorials individually and as a group, end-unit examinations scores, assessment of tutoring skills and identifying students' perceptions about peer tutoring. Student tutors were perceived better in providing feedback and in understanding the difficulties students face in tutorials. Tutorial atmosphere, decision-making and support for the group leader were better in SLT compared with FLT groups. Self-assessment of student performance in SLT was not different from FLT. Student scores in the written and practical examinations were comparable in both groups. However, SLT groups found difficulties in analysis of problems presented in the first tutorial session. We conclude that the impact of peer tutoring on student performance in tutorials, group dynamics, and student achievement in examinations is positive overall. However, student tutors require special training before adopting this approach in PBL programs.

  4. Community-based peer-led diabetes self-management: a randomized trial.

    Science.gov (United States)

    Lorig, Kate; Ritter, Philip L; Villa, Frank J; Armas, Jean

    2009-01-01

    The purpose of this study is to determine the effectiveness of a community-based diabetes self-management program comparing treatment participants to a randomized usual-care control group at 6 months. A total of 345 adults with type 2 diabetes but no criteria for high A1C were randomized to a usual-care control group or 6-week community-based, peer-led diabetes self-management program (DSMP). Randomized participants were compared at 6 months. The DSMP intervention participants were followed for an additional 6 months (12 months total). A1C and body mass index were measured at baseline, 6 months, and 12 months. All other data were collected by self-administered questionnaires. At 6 months, DSMP participants did not demonstrate improvements in A1C as compared with controls. Baseline A1C was much lower than in similar trials. Participants did have significant improvements in depression, symptoms of hypoglycemia, communication with physicians, healthy eating, and reading food labels (P < .01). They also had significant improvements in patient activation and self-efficacy. At 12 months, DSMP intervention participants continued to demonstrate improvements in depression, communication with physicians, healthy eating, patient activation, and self-efficacy (P < .01). There were no significant changes in utilization measures. These findings suggest that people with diabetes without elevated A1C can benefit from a community-based, peer-led diabetes program. Given the large number of people with diabetes and lack of low-cost diabetes education, the DSMP deserves consideration for implementation.

  5. 340 nm pulsed UV LED system for europium-based time-resolved fluorescence detection of immunoassays

    DEFF Research Database (Denmark)

    Rodenko, Olga; Fodgaard, Henrik; Tidemand-Lichtenberg, Peter

    2016-01-01

    We report on the design, development and investigation of an optical system based on UV light emitting diode (LED) excitation at 340 nm for time-resolved fluorescence detection of immunoassays. The system was tested to measure cardiac marker Troponin I with a concentration of 200 ng....../L in immunoassay. The signal-to-noise ratio was comparable to state-of-the-art Xenon flash lamp based unit with equal excitation energy and without overdriving the LED. We performed a comparative study of the flash lamp and the LED based system and discussed temporal, spatial, and spectral features of the LED...... excitation for time-resolved fluorimetry. Optimization of the suggested key parameters of the LED promises significant increase of the signal-to-noise ratio and hence of the sensitivity of immunoassay systems....

  6. Multi-band transmission color filters for multi-color white LEDs based visible light communication

    Science.gov (United States)

    Wang, Qixia; Zhu, Zhendong; Gu, Huarong; Chen, Mengzhu; Tan, Qiaofeng

    2017-11-01

    Light-emitting diodes (LEDs) based visible light communication (VLC) can provide license-free bands, high data rates, and high security levels, which is a promising technique that will be extensively applied in future. Multi-band transmission color filters with enough peak transmittance and suitable bandwidth play a pivotal role for boosting signal-noise-ratio in VLC systems. In this paper, multi-band transmission color filters with bandwidth of dozens nanometers are designed by a simple analytical method. Experiment results of one-dimensional (1D) and two-dimensional (2D) tri-band color filters demonstrate the effectiveness of the multi-band transmission color filters and the corresponding analytical method.

  7. 340nm UV LED excitation in time-resolved fluorescence system for europium-based immunoassays detection

    DEFF Research Database (Denmark)

    Rodenko, Olga; Fodgaard, Henrik; Tidemand-Lichtenberg, Peter

    2017-01-01

    In immunoassay analyzers for in-vitro diagnostics, Xenon flash lamps have been widely used as excitation light sources. Recent advancements in UV LED technology and its advantages over the flash lamps such as smaller footprint, better wall-plug efficiency, narrow emission spectrum......, and no significant afterglow, have made them attractive light sources for gated detection systems. In this paper, we report on the implementation of a 340 nm UV LED based time-resolved fluorescence system based on europium chelate as a fluorescent marker. The system performance was tested with the immunoassay based...... on the cardiac marker, TnI. The same signal-to-noise ratio as for the flash lamp based system was obtained, operating the LED below specified maximum current. The background counts of the system and its main contributors were measured and analyzed. The background of the system of the LED based unit was improved...

  8. Effectiveness of peer-led dissonance-based eating disorder prevention groups: results from two randomized pilot trials.

    Science.gov (United States)

    Stice, Eric; Rohde, Paul; Durant, Shelley; Shaw, Heather; Wade, Emily

    2013-05-01

    The present preliminary trials tested whether undergraduate peer leaders can effectively deliver a dissonance-based eating disorder prevention program, which could facilitate broad dissemination of this efficacious intervention. In Study 1, female undergraduates (N=171) were randomized to peer-led groups, clinician-led groups, or an educational brochure control condition. In Study 2, which improved a design limitation of Study 1 by using completely parallel outcome measures across conditions, female undergraduates (N=148) were randomized to either immediate peer-led groups or a waitlist control condition. In Study 1, participants in peer- and clinician-led groups showed significantly greater pre-post reductions in risk factors and eating disorder symptoms than controls (M d=.64 and .98 respectively), though clinician- versus peer-led groups had higher attendance and competence ratings, and produced stronger effects at posttest (M d=.32) and at 1-year follow-up (M d=.26). In Study 2, participants in peer-led groups showed greater pre-post reductions in all outcomes than waitlist controls (M d=.75). Results provide novel evidence that dissonance-based eating disorder prevention groups led by undergraduate peers are feasible and produce greater reductions in eating disorder risk factors and symptoms than minimal-intervention control conditions, but indicate that effects are smaller for peer- versus clinician-led groups. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. A Practical Solution for 77 K Fluorescence Measurements Based on LED Excitation and CCD Array Detector.

    Directory of Open Access Journals (Sweden)

    Jacob Lamb

    Full Text Available The fluorescence emission spectrum of photosynthetic microorganisms at liquid nitrogen temperature (77 K provides important insights into the organization of the photosynthetic machinery of bacteria and eukaryotes, which cannot be observed at room temperature. Conventionally, to obtain such spectra, a large and costly table-top fluorometer is required. Recently portable, reliable, and largely maintenance-free instruments have become available that can be utilized to accomplish a wide variety of spectroscopy-based measurements in photosynthesis research. In this report, we show how to build such an instrument in order to record 77K fluorescence spectra. This instrument consists of a low power monochromatic light-emitting diode (LED, and a portable CCD array based spectrometer. The optical components are coupled together using a fiber optic cable, and a custom made housing that also supports a dewar flask. We demonstrate that this instrument facilitates the reliable determination of chlorophyll fluorescence emission spectra for the cyanobacterium Synechocystis sp. PCC 6803, and the green alga Chlamydomonas reinhardtii.

  10. Impact of community based nurse-led clinics on patient outcomes, patient satisfaction, patient access and cost effectiveness: A systematic review.

    Science.gov (United States)

    Randall, Sue; Crawford, Tonia; Currie, Jane; River, Jo; Betihavas, Vasiliki

    2017-08-01

    The role and scope of nursing practice has evolved in response to the dynamic needs of individuals, communities, and healthcare services. Health services are now focused on maintaining people in their communities, and keeping them out of hospital where possible. Community based nurse-led clinics are ideally placed to work towards this goal. The initial impetus for these services was to increase patient access to care, to provide a cost-effective and high quality streamlined service. This systematic review aimed to identify the impact of nurse-led clinics in relation to patient outcomes, patient satisfaction, impact on patient access to services, and cost effectiveness. A review of community based nurse-led clinic research in Medline, CINAHL and Embase was undertaken using MeSH terms: Nurse-managed centres, Practice, Patterns, Nurse, Ambulatory Care, keywords: nurse-led clinic, nurse led clinic, community and phrases primary health care and primary care. Papers were appraised using the Joanna Briggs Appraisal criteria. The final review comprised 15 studies with 3965 participants. Most studies explored patient satisfaction which was largely positive towards nurse-led clinics. Patient outcomes reported were typically from self-report, although some papers addressed objective clinical measures; again positive. Access was reported as being increased. Cost-effectiveness was the least reported impact measure with mixed results. Nurse-led clinics have largely shown positive impact on patient outcomes, patient satisfaction, access to care and mixed results on cost-effectiveness. Future research evaluating NLCs needs to adopt a standardised structure to provide rigorous evaluations that can rationalise further efforts to set up community based nurse-led clinical services. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Lumen degradation analysis of LED lamps based on the subsystem isolation method.

    Science.gov (United States)

    Ke, Hong-Liang; Hao, Jian; Tu, Jian-Hui; Miao, Pei-Xian; Wang, Chao-Quan; Cui, Jing-Zhong; Sun, Qiang; Sun, Ren-Tao

    2018-02-01

    The lumen degradation of LED lamps undergoing an accelerated aging test is investigated. The entire LED lamp is divided into three subsystems, namely, driver, lampshade, and LED light source. The parameters of output power [Watts (W)], transmittance (%), and lumen flux (lm) are adopted in the analysis of the degradation of the driver, lampshade, and LED light source, respectively. Two groups of LED lamps are aged under the ambient temperatures of 25°C and 85°C, respectively, with the aging time of 2000 h. The lumen degradation of the lamps is from 3.8% to 4.9% for the group under a temperature of 25°C and from 10.6% to 12.7% for the group under a temperature of 85°C. The LED light source is the most aggressive part of the three subsystems, which accounts for 70.5% of the lumen degradation of the LED lamp on average. The lampshade is the second degradation source, which causes 21.5% of the total amount on average. The driver is the third degradation source, which causes 6.5% under 25°C and 2.8% under 85°C of the total amount on average.

  12. A large-area, LED-based spectral response measurement system for solar PV device characterization

    Science.gov (United States)

    Hamadani, Behrang; Roller, John; Yoon, Howard; Dougherty, Brian

    2012-02-01

    Accurate and reliable measurement of the spectral responsivity (SR) of a solar cell is an important step in evaluating the electrical performance of competing photovoltaic (PV) technologies. We have investigated ways to measure the spectral responsivity, and hence the external quantum efficiency, of solar cells using measurement techniques that employ light emitting diodes (LEDs). Our setup includes one or more plates of compactly-installed, high-powered LEDs each containing up to 32 different LEDs that span the wavelength range of 375 nm to 1200 nm. Each LED plate is placed at the entrance of a tapered, highly reflective light guide for light mixing and large-area projection. Two unique measurement techniques have been investigated at NIST. The first technique consists of an LED sweep algorithm where a pulsed signal is applied to a given LED and the photogenerated current from the device under test is recorded using a lock-in technique. In the second SR technique, 32 variable-frequency, pulsed signals are applied to all LEDs at the same time, while recording the photogenerated current by a spectrum analyzer in the frequency domain. We will describe the uniqueness and advantages offered by each technique in detail and compare the accuracy of the two methods. A scheme for providing light bias and its impact on the SR measurements will be reported.

  13. Automatic detecting method of LED signal lamps on fascia based on color image

    Science.gov (United States)

    Peng, Xiaoling; Hou, Wenguang; Ding, Mingyue

    2009-10-01

    Instrument display panel is one of the most important parts of automobiles. Automatic detection of LED signal lamps is critical to ensure the reliability of automobile systems. In this paper, an automatic detection method was developed which is composed of three parts in the automatic detection: the shape of LED lamps, the color of LED lamps, and defect spots inside the lamps. More than hundreds of fascias were detected with the automatic detection algorithm. The speed of the algorithm is quite fast and satisfied with the real-time request of the system. Further, the detection result was demonstrated to be stable and accurate.

  14. Deep Ultraviolet Light Emitting Diode (LED)-Based Sensing of Sulfur Dioxide.

    Science.gov (United States)

    Michel, Anna P M; Kapit, Jason

    2017-05-01

    With the recent development of deep ultraviolet (DUV) light emitting diodes (LEDs) comes the possibility of targeting absorption bands of several gases, including sulfur dioxide (SO 2 ). SO 2 has strong absorption bands in the 300 nm spectral region. The low cost and small size of DUV LEDs, coupled with their spectral coverage, makes them viable sources for new gas sensors. Here, we demonstrate the capability to use absorption spectroscopy with a balanced detection scheme using a 300 nm DUV LED source for SO 2 detection at concentrations ranging from less than 1 ppm to 50 ppm.

  15. Design method of freeform light distribution lens for LED automotive headlamp based on DMD

    Science.gov (United States)

    Ma, Jianshe; Huang, Jianwei; Su, Ping; Cui, Yao

    2018-01-01

    We propose a new method to design freeform light distribution lens for light-emitting diode (LED) automotive headlamp based on digital micro mirror device (DMD). With the Parallel optical path architecture, the exit pupil of the illuminating system is set in infinity. Thus the principal incident rays of micro lens in DMD is parallel. DMD is made of high speed digital optical reflection array, the function of distribution lens is to distribute the emergent parallel rays from DMD and get a lighting pattern that fully comply with the national regulation GB 25991-2010.We use DLP 4500 to design the light distribution lens, mesh the target plane regulated by the national regulation GB 25991-2010 and correlate the mesh grids with the active mirror array of DLP4500. With the mapping relations and the refraction law, we can build the mathematics model and get the parameters of freeform light distribution lens. Then we import its parameter into the three-dimensional (3D) software CATIA to construct its 3D model. The ray tracing results using Tracepro demonstrate that the Illumination value of target plane is easily adjustable and fully comply with the requirement of the national regulation GB 25991-2010 by adjusting the exit brightness value of DMD. The theoretical optical efficiencies of the light distribution lens designed using this method could be up to 92% without any other auxiliary lens.

  16. A long distance voice transmission system based on the white light LED

    Science.gov (United States)

    Tian, Chunyu; Wei, Chang; Wang, Yulian; Wang, Dachi; Yu, Benli; Xu, Feng

    2017-10-01

    A long distance voice transmission system based on a visible light communication technology (VLCT) is proposed in the paper. Our proposed system includes transmitter, receiver and the voice signal processing of single chip microcomputer. In the compact-sized LED transmitter, we use on-off-keying and not-return-to-zero (OOK-NRZ) to easily realize high speed modulation, and then systematic complexity is reduced. A voice transmission system, which possesses the properties of the low-noise and wide modulation band, is achieved by the design of high efficiency receiving optical path and using filters to reduce noise from the surrounding light. To improve the speed of the signal processing, we use single chip microcomputer to code and decode voice signal. Furthermore, serial peripheral interface (SPI) is adopted to accurately transmit voice signal data. The test results of our proposed system show that the transmission distance of this system is more than100 meters with the maximum data rate of 1.5 Mbit/s and a SNR of 30dB. This system has many advantages, such as simple construction, low cost and strong practicality. Therefore, it has extensive application prospect in the fields of the emergency communication and indoor wireless communication, etc.

  17. Experimental study of porous media flow using hydro-gel beads and LED based PIV

    Science.gov (United States)

    Harshani, H. M. D.; Galindo-Torres, S. A.; Scheuermann, A.; Muhlhaus, H. B.

    2017-01-01

    A novel experimental approach for measuring porous flow characteristics using spherical hydro-gel beads and particle image velocimetry (PIV) technique is presented. A transparent porous medium consisting of hydro-gel beads that are made of a super-absorbent polymer, allows using water as the fluid phase while simultaneously having the same refractive index. As a result, a more adaptable and cost effective refractive index matched (RIM) medium is created. The transparent nature of the porous medium allows optical systems to visualize the flow field by using poly-amide seeding particles (PSP). Low risk light emitting diode (LED) based light was used to illuminate the plane in order to track the seeding particles’ path for the characterization of the flow inside the porous medium. The system was calibrated using a manually measured flow by a flow meter. Velocity profiles were obtained and analysed qualitatively and quantitatively in order to characterise the flow. Results show that this adaptable, low risk experimental set-up can be used for flow measurements in porous medium under low Reynolds numbers. The limitations of using hydro-gel beads are also discussed.

  18. The difference nanocomposite hardness level using LED photoactivation based on curing period variations

    Directory of Open Access Journals (Sweden)

    Hasiana Tatian

    2011-03-01

    Full Text Available Polimerizatian is the critical stage to determine the quality of composites resin, this involves isolated monomer carbon double bonds being converted to an extended network of single bonds. Physical and mechanical properties of composites are influenced by the level of conversion attained during polymerization. An adequate light intensity and light curing time are important to obtain the degree of polymerization. The objective of this study is to evaluate the difference of the hardness nanocomposites which activated by LED LCU based on the variation of curing times. This study is a true experimental research. The samples were made from nanocomposites material with cylinder form of 4 mm in depth, 6 mm in diameter. This samples divided into 3 groups of curing times. Group, I was cured for 20's curing time as a control due to manufactory recommended; Group II was cured for 30's, and Group III was cured for 40's and the hardness (Rebound hardness tester was determined using Rebound scale (RS and converted by Mohs scale (MS. There was a very significant level of hardness rate from each group using ANOVA test. The result of the study concludes that there were the differences on the nanocomposites hardness level cured under different curing times 20, 30 and 40 sec. The longer of curing times, the higher level of hardness.

  19. 3D printed LED based on-capillary detector housing with integrated slit.

    Science.gov (United States)

    Cecil, Farhan; Zhang, Min; Guijt, Rosanne M; Henderson, Alan; Nesterenko, Pavel N; Paull, Brett; Breadmore, Michael C; Macka, Mirek

    2017-05-01

    A 3D printed photometric detector body with integrated slit was fabricated to position a LED and photodiode either side of capillary tubing using a fused deposition modelling (FDM) printer. To make this approach suitable for capillaries down to 50 μm i.d. the dimension of the in-built slit is the critical element of the printed housing. The spatial orientation of the model for printing was found to significantly impact on the resolution of the structures and voids that can be printed. By designing a housing with a slit positioned in the XY plane in parallel with the print direction, the narrowest void (slit) that could be printed was 70 μm. The potential use of the 3D printed slit for photometric detection was characterised using tubing and capillary from 500 down to 50 μm i.d, demonstrating a linear response from 632 to 40 mAU. The effective pathlength and stray light varied from 383 to 22 μm and 3.8% - 50% for 500- 50 μm i.d tubing and capillary. The use of a V-shaped alignment feature allowed for easy and reliable positioning of the tubing inside the detector, as demonstrated by a RSD of 1.9% (n = 10) in peak height when repositioning the tubing between measurements using flow injection analysis (FIA). The performance of the 3D printed housing and 70 μm slit was benchmarked against a commercially available interface using the CE separation of Zn 2+ and Cu 2+ complexes with PAR. The limit of detection with the 3D printed slit was 6.8 and 4.5 μM and is 2.8 and 1.6 μM with the commercial interface. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Ultraviolet-A LED Based on Quantum-disks-in-AlGaN-nanowires - Optimization and Device Reliability

    KAUST Repository

    Janjua, Bilal

    2018-03-16

    Group-III nitride-based ultraviolet (UV) quantum-disks (Qdisks) nanowires (NWs) light-emitting diodes grown on silicon substrates offer a scalable, environment-friendly, compact, and low-cost solution for numerous applications such as solid-state lighting, spectroscopy, and biomedical. However, the internal quantum efficiency, injection efficiency, and extraction efficiency need to be further improved. The focus of this paper encompasses investigations based on structural optimization, device simulation, and device reliability. To optimize a UV-A (320-400 nm) device structure we utilize the self-assembled quantum-disk-NWs with varying quantum-disks thickness to study carrier separation in active-region and implement an improved p-contact-layer to increase output power. By simulation, we found a 100° improvement in the direct recombination rate for samples with thicker Qdisks thickness of 1.2 nm compared to the sample with 0.6 nm-thick Qdisks. Moreover, the sample with graded top Mg-doped AlGaN layer in conjunction with thin Mg-doped GaN layer shows 10° improvement in the output power compared to the samples with thicker top Mg-doped GaN absorbing contact layer. A fitting with ABC model revealed the increase in non-radiative recombination centers in the active region after a soft stress-test. This work aims to shed light on the research efforts required for furthering the UV NWs LED research for practical applications.

  1. The Bluetooth Based LED Control For Arduino Test Platform By Using Mobile APP

    OpenAIRE

    Yi-Jen Mon

    2015-01-01

    Abstract The Bluetooth is a commonly known convenient and famous communication protocol. In this paper it is used to control LED mounted on Arduino test platform by using the APP of mobile phone. At first the control program is completed by Arduino development software environment then the Android APP is installed in mobile phone. Finally by using the Bluetooth of mobile phone the test platform will be connected. The LED can be controlled by APP of mobile phone. The experiment results are dem...

  2. Online learning in paediatrics: a student-led web-based learning modality.

    Science.gov (United States)

    Gill, Peter; Kitney, Lauren; Kozan, Daniel; Lewis, Melanie

    2010-03-01

    undergraduate medical education is shifting away from traditional didactic methods towards a more self-directed learning environment. E-learning has emerged as a vital learning modality that allows students to apply key principles to practical scenarios in a truly personalised approach.  at the University of Alberta, paediatrics is taught longitudinally, with lectures distributed throughout the preclinical curriculum and concentrated in the 8-week paediatric clinical clerkship. As a result, students entering clerkship lack core foundational knowledge and clinical skills. PedsCases (http://www.pedscases.com) is a student-driven interactive website designed to achieve the learning outcomes identified by the competency-based paediatric curriculum. This open-access e-learning tool is a comprehensive peer-reviewed learning resource that incorporates various learning modalities. Material is student generated and peer reviewed by staff paediatricians to ensure validity, accuracy and usefulness. After 17 months, PedsCases contains 216 questions, 19 cases, 11 flashcard-type quizzes, 11 podcasts and two clinical videos, and has had 2148 unique visitors from 73 different countries. PedsCases is one of the top five references returned by Internet search engines for the phrase 'paediatrics for medical students'. PedsCases is a collaborative resource created for and by medical students that provides an opportunity for active self-directed learning while disseminating knowledge in an evidence-based, interactive and clinically relevant fashion. PedsCases encourages students to take an active role in their education and drive medical education initiatives in response to the evolving curriculum. As the focus of medical education shifts towards independent learning, student-led educational tools such as PedsCases have emerged as essential resources for students. © Blackwell Publishing Ltd 2010.

  3. Factors associated with the implementation of community-based peer-led health promotion programs: A scoping review.

    Science.gov (United States)

    Lorthios-Guilledroit, Agathe; Richard, Lucie; Filiatrault, Johanne

    2018-02-03

    Peer education is growing in popularity as a useful health promotion strategy. However, optimal conditions for implementing peer-led health promotion programs (HPPs) remain unclear. This scoping review aimed to describe factors that can influence implementation of peer-led HPPs targeting adult populations. Five databases were searched using the keywords "health promotion/prevention", "implementation", "peers", and related terms. Studies were included if they reported at least one factor associated with the implementation of community-based peer-led HPPs. Fifty-five studies were selected for the analysis. The method known as "best fit framework synthesis" was used to analyze the factors identified in the selected papers. Many factors included in existing implementation conceptual frameworks were deemed applicable to peer-led HPPs. However, other factors related to individuals, programs, and implementation context also emerged from the analysis. Based on this synthesis, an adapted theoretical framework was elaborated, grounded in a complex adaptive system perspective and specifying potential mechanisms through which factors may influence implementation of community-based peer-led HPPs. Further research is needed to test the theoretical framework against empirical data. Findings from this scoping review increase our knowledge of the optimal conditions for implementing peer-led HPPs and thereby maximizing the benefits of such programs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Integrated luminescent chemical microsensors based on GaN LEDs for security applications using smartphones

    Science.gov (United States)

    Orellana, Guillermo; Muñoz, Elias; Gil-Herrera, Luz K.; Muñoz, Pablo; Lopez-Gejo, Juan; Palacio, Carlos

    2012-09-01

    Development of PCB-integrateable microsensors for monitoring chemical species is a goal in areas such as lab-on-a-chip analytical devices, diagnostics medicine and electronics for hand-held instruments where the device size is a major issue. Cellular phones have pervaded the world inhabitants and their usefulness has dramatically increased with the introduction of smartphones due to a combination of amazing processing power in a confined space, geolocalization and manifold telecommunication features. Therefore, a number of physical and chemical sensors that add value to the terminal for health monitoring, personal safety (at home, at work) and, eventually, national security have started to be developed, capitalizing also on the huge number of circulating cell phones. The chemical sensor-enabled "super" smartphone provides a unique (bio)sensing platform for monitoring airborne or waterborne hazardous chemicals or microorganisms for both single user and crowdsourcing security applications. Some of the latest ones are illustrated by a few examples. Moreover, we have recently achieved for the first time (covalent) functionalization of p- and n-GaN semiconductor surfaces with tuneable luminescent indicator dyes of the Ru-polypyridyl family, as a key step in the development of innovative microsensors for smartphone applications. Chemical "sensoring" of GaN-based blue LED chips with those indicators has also been achieved by plasma treatment of their surface, and the micrometer-sized devices have been tested to monitor O2 in the gas phase to show their full functionality. Novel strategies to enhance the sensor sensitivity such as changing the length and nature of the siloxane buffer layer are discussed in this paper.

  5. Improving current spreading of GaN-based LEDs by N-pad current surrounding design

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Chun-Fu [Institute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, No. 1 University Road, Tainan City (China); Su, Yan-Kuin [Institute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, No. 1 University Road, Tainan City (China); Department of Electrical Engineering, Kun-Shan University, Yung-Kang City, Tainan County 710 (China); Lin, Chun-Liang [Department of Electronic Engineering, Kun-Shan University, Yung-Kang City, Tainan County 710 (China)

    2010-07-15

    In this report, the motivation of why we attempt to design current spreading, or current surrounding, is try to provide other current paths, expect to improve the current spreading of LEDs and get lower forward voltage at the same time. Attempt to avoid the trade-off between p -electrode area for uniform current spreading and emitting area for light output of LEDs. Compared to reference LEDs, we can find that the light output intensity of chips with n -pad current surrounding design will decay at higher current injection. This can be attributed to the metal on pitch we design, with better current spreading and much metal area connected to n -pad, so less current crowding effect and less heat-accumulation in chips (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Feasibility of a peer-led, school-based asthma education programme for adolescents in Jordan.

    Science.gov (United States)

    Al-Sheyab, N A; Gallagher, R; Roydhouse, J K; Crisp, J; Shah, S

    2012-05-01

    The Adolescent Asthma Action programme (Triple A) has been used successfully to promote asthma knowledge, awareness and quality of life in adolescents with asthma in Australia. We describe the feasibility and acceptability of an adaptation of this English-language, peer-led, asthma education programme in a girls' high school in Northern Jordan. The pilot was conducted by bilingual health workers. Feasibility, acceptability and adaptability were measured through participation rates, open-ended questionnaires completed by peer leaders, a focus group for junior students and reflective journal notes. The programme was well-received by staff and students, with high levels of participation. The peer-led approach was viewed positively. Students reported that they enjoyed the interactive learning activities and the opportunity to practise English. The students reported increased asthma knowledge and awareness, with students with asthma reporting receiving more support from peers. A peer-led asthma education programme is feasible and acceptable in the Jordanian school context.

  7. Crosstalk reduction in large-scale autostereoscopic 3D-LED display based on black-stripe occupation ratio

    Science.gov (United States)

    Zeng, Xiang-Yao; Zhou, Xiong-Tu; Guo, Tai-Liang; Yang, Lan; Chen, En-Guo; Zhang, Yong-Ai

    2017-04-01

    Autostereoscopic 3D-LED displays using parallax barriers have several advantages. However, conventional designs do not consider the black stripes of regular LED panels. These cause immeasurable crosstalk owing to excess light from adjacent sub-pixels separated by the panels. To reduce the crosstalk in large-scale displays, we design a barrier in which the black-stripe occupation ratio is defined to quantify the crosstalk level in the LED system. A prototype is assembled and analyzed based on a three-in-one pixel LED-chip panel for a dual-viewpoint display. The improved parallax barrier meets the design requirements and achieves a low crosstalk level. Simulation and experiment results verify the effectiveness of the crosstalk-reduced design.

  8. The Bluetooth Based LED Control For Arduino Test Platform By Using Mobile APP

    Directory of Open Access Journals (Sweden)

    Yi-Jen Mon

    2015-06-01

    Full Text Available Abstract The Bluetooth is a commonly known convenient and famous communication protocol. In this paper it is used to control LED mounted on Arduino test platform by using the APP of mobile phone. At first the control program is completed by Arduino development software environment then the Android APP is installed in mobile phone. Finally by using the Bluetooth of mobile phone the test platform will be connected. The LED can be controlled by APP of mobile phone. The experiment results are demonstrated the effective performance.

  9. Miniaturized tool for optogenetics based on an LED and an optical fiber interfaced by a silicon housing.

    Science.gov (United States)

    Schwaerzle, M; Elmlinger, P; Paul, O; Ruther, P

    2014-01-01

    This paper reports on the design, simulation, fabrication and characterization of a tool for optogenetic experiments based on a light emitting diode (LED). A minimized silicon (Si) interface houses the LED and aligns it to an optical fiber. With a Si housing size of 550×500×380 μm(3) and an electrical interconnection of the LED by a highly flexible polyimide (PI) ribbon cable is the system very variable. PI cables and Si housings are fabricated using established microsystem technologies. A 270×220×50 μm(3) bare LED chip is flip-chip-bonded onto the PI cable. The Si housing is adhesively attached to the PI cable, thereby hosting the LED in a recess. An opposite recess guides the optical fiber with a diameter of 125 μm. An aperture in-between restricts the emitted LED light to the fiber core. The optical fiber is adhesively fixed into the Si housing recess. An optical output intensity at the fiber end facet of 1.71 mW/mm(2) was achieved at a duty cycle of 10 % and a driving current of 30 mA.

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

    Science.gov (United States)

    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.

  11. LED lamp

    Science.gov (United States)

    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.

  12. Design bases - Concrete structures

    International Nuclear Information System (INIS)

    Diaz-Llanos Ros, M.

    1993-01-01

    The most suitable title for Section 2 is 'Design Bases', which covers not only calculation but also the following areas: - Structural design concepts. - Project criteria. - Material specifications. These concepts are developed in more detail in the following sections. The numbering in this document is neither complete nor hierarchical since, for easier cross referencing, it corresponds to the paragraphs of Eurocode 2 Part 1 (hereinafter 'EUR-2') which are commented on. (author)

  13. Structured Simulation-Based Training Programs: History and Lessons Learned

    National Research Council Canada - National Science Library

    Shlechter, Theodore

    2000-01-01

    ...) research and development (R&D) efforts on structured simulation-based training (SST). These R&D efforts have led to the development of 30 research reports, 14 conference papers, and over 200 training support packages (TSPs...

  14. Design considerations for AlGaN-based UV LEDs emitting near 235 nm with uniform emission pattern

    Science.gov (United States)

    Lapeyrade, Mickael; Glaab, Johannes; Knauer, Arne; Kuhn, Christian; Enslin, Johannes; Reich, Christoph; Guttmann, Martin; Mehnke, Frank; Wernicke, Tim; Einfeldt, Sven; Weyers, Markus; Kneissl, Michael

    2017-04-01

    The uniformity of emission from deep ultraviolet light emitting diodes (UV LEDs) is investigated. The AlGaN-based heterostructures of the UV LEDs emitting around 235 nm were grown by metalorganic vapor phase epitaxy on epitaxially laterally overgrown AlN/sapphire substrates. The impact of different device designs on the spatial distribution of the electroluminescence for a series of UV LEDs is studied. Due to the relatively high resistivities of n-AlGaN and p-AlGaN layers, ranging from 10 to 0.1 Ω cm as well as specific contact resistances approaching 1 Ω cm2, the emission patterns revealed heavy current crowding at the mesa edges causing a drop of power in the center of the emitting area and an asymmetry towards the side of the bonding pad of the n-contact. Simple analytical models considering the transfer and the current spreading length could only qualitatively explain the observed emission pattern. Using a 3D electro-thermal simulation of the current spreading in the LEDs the experimentally observed emission pattern could also be quantitatively reproduced. Based on these findings the 3D electro-thermal simulation was employed to optimize the contact geometry of the deep UV LEDs in order to achieve a more uniform power distribution.

  15. Sidestream Dark Field (SDF) imaging: a novel stroboscopic LED ring-based imaging modality for clinical assessment of the microcirculation

    NARCIS (Netherlands)

    Goedhart, P. T.; Khalilzada, M.; Bezemer, R.; Merza, J.; Ince, C.

    2007-01-01

    Sidestream Dark Field (SDF) imaging, a stroboscopic LED ring-based imaging modality, is introduced for clinical observation of the microcirculation. SDF imaging is validated by comparison to Orthogonal Polarization Spectral imaging. Nailfold capillary diameters and red blood cell velocities were

  16. Teaching Innovations in Marketing: A Brand-Based Student-Led Inquiry of Marketing Concepts and Practices

    Science.gov (United States)

    Hostetter, Leonard R., Jr.

    2017-01-01

    This teaching innovation is a brand-based student-led inquiry of marketing concepts and practices for an introductory marketing course. During the first week of class, teams of students (or individual students) each select a brand of interest to research and analyze throughout the course. The objective is for students to understand the practical…

  17. Large-signal modulation characteristics of a GaN-based micro-LED for Gbps visible-light communication

    Science.gov (United States)

    Tian, Pengfei; Wu, Zhengyuan; Liu, Xiaoyan; Fang, Zhilai; Zhang, Shuailong; Zhou, Xiaolin; Liu, Kefu; Liu, Ming-Gang; Chen, Shu-Jhih; Lee, Chia-Yu; Cong, Chunxiao; Hu, Laigui; Qiu, Zhi-Jun; Zheng, Lirong; Liu, Ran

    2018-04-01

    The large-signal modulation characteristics of a GaN-based micro-LED have been studied for Gbps visible-light communication. With an increasing signal modulation depth the modulation bandwidth decreases, which matches up with the increase in the sum of the signal rise time and fall time. By simulating the band diagram and the carrier recombination rate of the micro-LED under large-signal modulation, carrier recombination and the carrier sweep-out effect are analyzed and found to be the dominant mechanisms behind the variation of modulation bandwidth. These results give further insight into improving the modulation bandwidth for high-speed visible-light communication.

  18. 3.4 Gbit/s visible optical wireless transmission based on RGB LED.

    Science.gov (United States)

    Cossu, G; Khalid, A M; Choudhury, P; Corsini, R; Ciaramella, E

    2012-12-10

    In this paper, we experimentally realized a gigabit-class indoor visible light communication system using commercially available RGB White LED and exploiting an optimized DMT modulation. We achieved data rate of 1.5 Gbit/s with single channel and 3.4 Gbit/s by implementing WDM transmission at standard illumination levels. In both experiments, the resulting bit error ratios were below the FEC limit. To the best of our knowledge, these values are the highest ever achieved in VLC systems.

  19. Validation of the spectral mismatch correction factor using an LED-based solar simulator

    DEFF Research Database (Denmark)

    Riedel, Nicholas; Santamaria Lancia, Adrian Alejo; Thorsteinsson, Sune

    -halide light sources provide. In this work we will use an EcoSun10L LED module tester from Ecoprogetti to perform short circuit current (ISC) measurements under various class A, B and C spectra. We will apply a spectral mismatch correction to the measured ISC under each test spectrum per IEC 60904-7. In all...... scenarios, a small area mono-Si cell is used the reference cell and a similar mono-Si cell is used as the PV device under test (DUT). Finally, we quantify the variation of the DUT’s measured and spectrally corrected Isc under the class A, B and C test spectra....

  20. Optogenetic activation of neocortical neurons in vivo with a sapphire-based micro-scale LED probe

    Directory of Open Access Journals (Sweden)

    Niall eMcAlinden

    2015-05-01

    Full Text Available Optogenetics has proven to be a revolutionary technology in neuroscience and has advanced continuously over the past decade. However, optical stimulation technologies for in vivo need to be developed to match the advances in genetics and biochemistry that have driven this field. In particular, conventional approaches for in vivo optical illumination have a limitation on the achievable spatio-temporal resolution. Here we utilize a sapphire-based microscale gallium nitride light-emitting diode (µLED probe to activate neocortical neurons in vivo. The probes were designed to contain independently controllable multiple µLEDs, emitting at 450 nm wavelength with an irradiance of up to 2 W/mm2. Monte-Carlo stimulations predicted that optical stimulation using a µLED can modulate neural activity within a localized region. To validate this prediction, we tested this probe in the mouse neocortex that expressed channelrhodopsin-2 (ChR2 and compared the results with optical stimulation through a fiber at the cortical surface. We confirmed that both approaches reliably induced action potentials in cortical neurons and that the µLED probe evoked strong responses in deep neurons. Due to the possibility to integrate many optical stimulation sites onto a single shank, the µLED probe is thus a promising approach to control neurons locally in vivo.

  1. Thermal management for LED applications

    CERN Document Server

    Poppe, András

    2014-01-01

    Thermal Management for LED Applications provides state-of-the-art information on recent developments in thermal management as it relates to LEDs and LED-based systems and their applications. Coverage begins with an overview of the basics of thermal management including thermal design for LEDs, thermal characterization and testing of LEDs, and issues related to failure mechanisms and reliability and performance in harsh environments. Advances and recent developments in thermal management round out the book with discussions on advances in TIMs (thermal interface materials) for LED applications, advances in forced convection cooling of LEDs, and advances in heat sinks for LED assemblies. This book also: Presents a comprehensive overview of the basics of thermal management as it relates to LEDs and LED-based systems Discusses both design and thermal management considerations when manufacturing LEDs and LED-based systems Covers reliability and performance of LEDs in harsh environments Has a hands-on applications a...

  2. Simulation-Based Optimization of Cure Cycle of Large Area Compression Molding for LED Silicone Lens

    Directory of Open Access Journals (Sweden)

    Min-Jae Song

    2015-01-01

    Full Text Available Three-dimensional heat transfer-curing simulation was performed for the curing process by introducing a large area compression molding for simultaneous forming and mass production for the lens and encapsulants in the LED molding process. A dynamic cure kinetics model for the silicone resin was adopted and cure model and analysis result were validated and compared through a temperature measurement experiment for cylinder geometry with cure model. The temperature deviation between each lens cavity could be reduced by implementing a simulation model on the large area compression mold and by optimizing the location of heat source. A two-step cure cycle was constructed to reduce excessive reaction peak at the initial stage and cycle time. An optimum cure cycle that could reduce cycle time by more than 29% compared to a one-step cure cycle by adjusting dwell temperature, heating rate, and dwell time was proposed. It was thus confirmed that an optimization of large area LED lens molding process was possible by using the present experiment and the finite element method.

  3. Prediction of Lumen Output and Chromaticity Shift in LEDs Using Kalman Filter and Extended Kalman Filter Based Models

    Energy Technology Data Exchange (ETDEWEB)

    Lall, Pradeep; Wei, Junchao; Davis, J Lynn

    2014-06-24

    Abstract— Solid-state lighting (SSL) luminaires containing light emitting diodes (LEDs) have the potential of seeing excessive temperatures when being transported across country or being stored in non-climate controlled warehouses. They are also being used in outdoor applications in desert environments that see little or no humidity but will experience extremely high temperatures during the day. This makes it important to increase our understanding of what effects high temperature exposure for a prolonged period of time will have on the usability and survivability of these devices. Traditional light sources “burn out” at end-of-life. For an incandescent bulb, the lamp life is defined by B50 life. However, the LEDs have no filament to “burn”. The LEDs continually degrade and the light output decreases eventually below useful levels causing failure. Presently, the TM-21 test standard is used to predict the L70 life of LEDs from LM-80 test data. Several failure mechanisms may be active in a LED at a single time causing lumen depreciation. The underlying TM-21 Model may not capture the failure physics in presence of multiple failure mechanisms. Correlation of lumen maintenance with underlying physics of degradation at system-level is needed. In this paper, Kalman Filter (KF) and Extended Kalman Filters (EKF) have been used to develop a 70-percent Lumen Maintenance Life Prediction Model for LEDs used in SSL luminaires. Ten-thousand hour LM-80 test data for various LEDs have been used for model development. System state at each future time has been computed based on the state space at preceding time step, system dynamics matrix, control vector, control matrix, measurement matrix, measured vector, process noise and measurement noise. The future state of the lumen depreciation has been estimated based on a second order Kalman Filter model and a Bayesian Framework. Life prediction of L70 life for the LEDs used in SSL luminaires from KF and EKF based models have

  4. Service development of a nurse-led community-based PICC insertion service.

    Science.gov (United States)

    Bedford, Eva; Waterhouse, Dee

    2017-01-26

    Patients receiving intravenous therapy require reliable venous access. Typically patients with poor peripheral access or requiring long-term treatment from an outpatient antibiotic therapy (OPAT) service need to receive secondary care input for safe central line placement, and radiological confirmation of the correct line tip placement where necessary, if treatment is to proceed as planned. Technological developments that enable accurate ultrasound-guided vein selection and electrocardiograph (ECG)-guided central line tip placement have eliminated the need for radiological or fluoroscopic confirmation of correct tip placement for peripherally placed central catheters (PICCs). This article outlines the development of an out-of-hospital nurse-led PICC insertion service using the Sherlock 3CG ® Tip Confirmation System (C.R Bard) to meet the needs of patients requiring long-term intravenous treatment from an OPAT service, and its impact on reducing treatment delays and the need for secondary care intervention.

  5. Measurement of the indium segregation in InGaN based LEDs with single atom sensitivity

    International Nuclear Information System (INIS)

    Jinschek, Joerg; Kisielowski, Christian; Van Dyck, Dirk; Geuens, Philippe

    2003-01-01

    In light emitting diodes (LED) consisting of GaN/InGaN/GaN quantum wells (QWs), the exact indium distribution inside the wells of the active region affects the performance of devices. Indium segregation can take place forming small InGaN clusters of locally varying composition. In the past, we used a local strain analysis from single HRTEM lattice images to determine the In composition inside the InGaN QWs with a resolution of 0.5 nm x 0.3 nm. Truly atomic resolution can be pursued by exploitation of intensity dependencies on the atomic number (Z) of the electron exit-wave (EW). In microscopes with sufficient sensitivity, local variations of amplitude and phase are found to be discrete with sample thickness, which allows for counting the number of atoms in each individual column of ∼0.08 nm diameter. In QW s of ∼17 percent of average indium concentration it is possible to discriminate between pure Ga columns and columns containing 1, 2, 3, or more In atoms because phase changes are discrete and element specific. The preparation of samples with atomically flat surfaces is a limiting factor for the application of the procedure

  6. Scaling-Up Youth-Led Social Justice Efforts through an Online School-Based Social Network.

    Science.gov (United States)

    Kornbluh, Mariah; Neal, Jennifer Watling; Ozer, Emily J

    2016-06-01

    The exploration of social networking sites (SNS) in promoting social change efforts offers great potential within the field of community psychology. Online communities on SNS provide opportunities for bridging across groups, thus fostering the exchange of novel ideas and practices. Currently, there have only been limited efforts to examine SNS within the context of youth-led efforts. To explore the potential of SNS to facilitate the diffusion of social justice efforts between distinct youth groups, we linked three school-based youth-led participatory action research projects involving 54 high school students through a SNS. This study offers an innovative methodological approach and framework, utilizing social network analysis and strategic sampling of key student informants to investigate what individual behaviors and online network features predict student adoption of social change efforts. Findings highlight prospective facilitators and barriers to diffusion processes within a youth-led online network, as well as key constructs that may inform future research. We conclude by providing suggestions for scholars and practitioners interested in examining how SNS can be used to enhance the diffusion of social justice strategies, youth-led engagement efforts, and large-scale civic organizing. © Society for Community Research and Action 2016.

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

    KAUST Repository

    Janjua, Bilal

    2016-08-10

    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.

  8. Fabrication of nano-patterned sapphire substrates and their application to the improvement of the performance of GaN-based LEDs

    International Nuclear Information System (INIS)

    Gao Haiyong; Yan Fawang; Zhang Yang; Li Jinmin; Zeng Yiping; Wang Guohong

    2008-01-01

    Nano-patterned sapphire substrates (NPSSs) were fabricated by a chemical wet etching technology using nano-sized SiO 2 as masks. The NPSS was applied to improve the performance of GaN-based light emitting diodes (LEDs). GaN-based LEDs on NPSSs were grown by metal organic chemical vapour deposition. The characteristics of LEDs grown on NPSSs and conventional planar sapphire substrates were studied. The light output powers of the LEDs fabricated on NPSSs were considerably enhanced compared with that of the conventional LEDs grown on planar sapphire substrates

  9. Robust spectrometer-based methods for characterizing radiant exitance of dental LED light curing units.

    Science.gov (United States)

    Shortall, Adrian C; Felix, Christopher J; Watts, David C

    2015-04-01

    Firstly, to assess light output, from a representative range of dental light curing units (LCUs), using a new portable spectrometer based instrument (checkMARC™) compared with a "gold standard" method. Secondly, to assess possible inconsistency between light output measurements using three different laboratory-grade thermopile instruments. The output of four blue-dental LCUs and four polywave blue-and-violet-LCUs was measured with two spectrometer-based systems: a portable spectrometer instrument and a benchtop Integrating Sphere fiber-coupled spectrometer system. Power output was also recorded with three thermopiles according to ISO 10650-2. Beam profile images were recorded of LCU output to assess for spatial and spectral beam uniformity. Power recorded with the portable spectrometer instrument closely matched the 'gold standard' Integrating Sphere apparatus calibrated according to International Standards. Radiant exitance for the eight LCUs differed significantly between the three thermopiles. Light source to thermopile sensor distance influenced recorded power significantly (pSpectrometer-based methods are capable of overcoming the limitations inherent with thermopile-based measurement techniques. Spectrometer based measurements can fulfill the intention of ISO 10650. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Thermal resistance investigations on new leadframe-based LED packages and boards

    NARCIS (Netherlands)

    Pardo, B.; Gasse, A.; Fargeix, A.; Jakovenko, J.; Werkhoven, R.J.; Perpiñà, X.; Jordà, X.; Vellhevi, M.; Weelden, T. van; Bancken, P.

    2013-01-01

    In Solid State Lighting, thermal management is a key issue. Within the C-SSL consortium, we have developed an advanced leadframe based package to reduce the thermal resistance of the component. Numerical simulations have been implemented using Ansys® software and thermal measurements have been

  11. Broadband Radiometric LED Measurements.

    Science.gov (United States)

    Eppeldauer, G P; Cooksey, C C; Yoon, H W; Hanssen, L M; Podobedov, V B; Vest, R E; Arp, U; Miller, C C

    2016-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

  12. Nursing-led management of side effects of radiation: evidence-based recommendations for practice

    Directory of Open Access Journals (Sweden)

    Poirier P

    2013-03-01

    Full Text Available Patricia PoirierUniversity of Maine School of Nursing, Orono, ME, USAAbstract: It has been estimated that 50%–60% of patients diagnosed with cancer will receive radiation therapy at some point in their treatment. Although radiation therapy can play a significant role in the cure or control of cancer, and the palliation of symptoms, it also has side effects. Side effects of radiation therapy can interfere with patient quality of life and daily functioning. Severe side effects can lead to delays in treatment, potentially affecting the outcome of treatment. All patients receiving radiation therapy are at risk of fatigue and skin reactions in the area of the body being treated. Other side effects of radiation therapy are specific to the part of the body being treated. Radiation therapy to the head and neck area may cause oral mucositis, dryness, and nutritional deficiencies. Radiation therapy to the chest or lung area may lead to difficulty in swallowing and eating. Radiation therapy to the pelvis frequently causes diarrhea. There are many nursing interventions available to manage the side effects of treatment based on best available evidence and expert opinion. Nurses in all settings are essential in helping patients manage the side effects of treatment and maintain their quality of life. The purpose of this review is to provide nurses with evidence-based recommendations and suggestions for managing common acute side effects of radiation therapy.Keywords: evidence-based practice, radiation therapy, side effects, nursing management

  13. High-speed underwater optical wireless communication using a blue GaN-based micro-LED.

    Science.gov (United States)

    Tian, Pengfei; Liu, Xiaoyan; Yi, Suyu; Huang, Yuxin; Zhang, Shuailong; Zhou, Xiaolin; Hu, Laigui; Zheng, Lirong; Liu, Ran

    2017-01-23

    High-speed underwater optical wireless communication (UOWC) was achieved using an 80 μm blue-emitting GaN-based micro-LED. The micro-LED has a peak emission wavelength of ~440 nm and an underwater power attenuation of 1 dB/m in tap water. The -3 dB electrical-to-optical modulation bandwidth of the packaged micro-LED increases with increasing current and saturates at ~160 MHz. At an underwater distance of 0.6 m, 800 Mb/s data rate was achieved with a bit error rate (BER) of 1.3 × 10-3, below the forward error correction (FEC) criteria. And we obtained 100 Mb/s data communication speed with a received light output power of -40 dBm and a BER of 1.9 × 10-3, suggesting that UOWC with extended distance can be achieved. Through reflecting the light emission beam by mirrors within a water tank, we experimentally demonstrated a 200 Mb/s data rate with a BER of 3.0 × 10-6 at an underwater distance of 5.4 m.

  14. The effects of binding type on luminescence LED phosphor based on GGG/Ce3+

    Science.gov (United States)

    Mikhailov, M. M.; Neshchimenko, V. V.; Shavlyuk, V. V.

    2014-12-01

    Luminescence and reflectance spectra of coatings based on gadolinium gallium garnet doped by cerium (GGG/Ce3+) with silicone resin or potassium liquid glass compound were analyzed depending on concentration. It was established that the maximum emissions of the coatings at 75 wt.% compound concentration have luminescence band at 570 nm and absorption band at 470 nm. Both bands were detected by absorption or emission of cerium ions in gadolinium gallium garnet. Ce3+ ion transition into Ce4+ ion was observed upon quantum absorption, and the reverse transition was observed upon quantum emission.

  15. Consumer-led development of novel sea-buckthorn based beverages

    DEFF Research Database (Denmark)

    Geertsen, Julie Leth; Allesen-Holm, Bodil Helene; Giacalone, Davide

    2016-01-01

    In the context of a growing interest toward foods of local origin, this research explored consumer perceptions of novel sea-buckthorn-based beverages (SBBs), developed by combining sea-buckthorn (hippophae rhamnoides L.) berries in combination with other locally sourced ingredients. Specifically...... characteristics were the most important drivers of consumer preferences within this product category. Practical Applications This study offers new insights into consumers’ perception of novel food products of local origin. A key issue with such ingredients is that they have unique sensory properties which...... the products and identified most promising prototypes, and could, therefore, be beneficially applied to support product development efforts among small and medium-sized local producers....

  16. Novel Transparent Phosphor Conversion Matrix with High Thermal Conductivity for Next Generation Phosphor-Converted LED-based Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Bockstaller, Michael [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2017-02-06

    The low thermal conductivity of state-of-the-art polymer encapsulants (k ~ 0.15 Wm-1K-1) limits the efficiency and power density of current phosphor conversion light emitting diodes (pc-LEDs). The technical objective of this project was to demonstrate synthesis and processing schemes for the fabrication of polymer hybrid encapsulants with a thermal conductivity exceeding k = 0.4 Wm-1K-1 for LED applications. The ‘hybrid polymer’ approach encompasses the dispersion of high thermal conductivity particle fillers (zinc oxide, ZnO as well as the alpha-polymorph of alumina, Al2O3) within a polysiloxane matrix (poly(dimethylsiloxane), PDMS as well as poly(phenyl methyl siloxane), PPMS) to increase the thermal conductivity while maintaining optical transparency and photothermal stability at levels consistent with LED applications. To accomplish this goal, a novel synthesis method for the fabrication of nanosized ZnO particles was developed and a novel surface chemistry was established to modify the surface of zinc oxide particle fillers and thus to enable their dispersion in poly(dimethyl siloxane) (PDMS) matrix polymers. Molecular dynamics and Mie simulations were used to optimize ligand structure and to enable the concurrent mixing of particles in PDMS/PPMS embedding media while also minimizing the thermal boundary resistance as well as optical scattering of particle fillers. Using this approach the synthesis of PDMS/ZnO hybrid encapsulants exhibiting a thermal conductivity of 0.64 Wm-1K-1 and optical transparency > 0.7 mm-1 was demonstrated. A forming process based on micromolding was developed to demonstrate the forming of particle filled PDMS into film and lens shapes. Photothermal stability testing revealed stability of the materials for approximately 4000 min when exposed to blue light LED (450 nm, 30 W/cm2). One postgraduate and seven graduate students were supported by the project. The research performed within this project led to fifteen publications in peer

  17. Demonstration of 575-Mb/s downlink and 225-Mb/s uplink bi-directional SCM-WDM visible light communication using RGB LED and phosphor-based LED.

    Science.gov (United States)

    Wang, Yuanquan; Wang, Yiguang; Chi, Nan; Yu, Jianjun; Shang, Huiliang

    2013-01-14

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10(-3) after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

  18. LED-FISH: Fluorescence microscopy based on light emitting diodes for the molecular analysis of Her-2/neu oncogene amplification

    Directory of Open Access Journals (Sweden)

    Vollmer Ekkehard

    2008-12-01

    Full Text Available Abstract Light emitting diodes (LED, which are available as small monochromatic light sources with characteristic features such as maximum illumination power combined with minimum energy consumption and extremely long lifespan have already proved as a highly potential low-cost alternative for specific diagnostic applications in clinical medicine such as tuberculosis fluorescence microscopy. Likewise, the most reliable evaluation of Her-2/neu (c-erbB2 gene amplification, which has been established in the last few years for routine diagnosis in clinical pathology as determinant towards Herceptin-based treatment of patients with breast cancer, is based on fluorescence in situ hybridization (FISH and corresponding high priced fluorescence equipment. In order to test the possibility to utilize the advantages of low-cost LED technology on FISH analysis of c-erbB2 gene expression for routine diagnostic purposes, the applicability of a standard bright field Carl Zeiss Axiostar Plus microscope equipped with a Fraen AFTER* LED Fluorescence Microscope Kit for the detection of Her-2/neu gene signals was compared to an advanced Nikon Eclipse 80i fluorescence microscope in combination with a conventional 100W mercury vapor lamp. Both microscopes were fitted with the same Quicam FAST CCD digital camera to unequivocally compare the quality of the captured images. C-erbB2 gene expression was analyzed in 30 different human tissue samples of primary invasive breast cancer, following formalin fixation and subsequent paraffin-embedding. The Her2/neu gene signals (green were identifiable in the tumor cells in all cases and images of equal quality were captured under almost identical conditions by 480 nm (blue LED module equipped standard Axiostar microscope as compared to conventional fluorescence microscopy. In this first attempt, these monochromatic LED elements proved in principle to be suitable for the detection of Her-2/neu gene expression by FISH. Thus, our own

  19. Effectiveness of composite resin polymerization using light-emitting diodes (LEDs) or halogen-based light-curing units

    OpenAIRE

    Micali,Bianca; Basting,Roberta Tarkany

    2004-01-01

    The clinical performance of composite resins is greatly influenced by the quality of the light-curing unit used. The aim of this study was to compare the efficiency of a commercial light-emitting diode (LED) with that of a halogen-based light-curing unit by means of dye penetration of a micro hybrid composite resin. The composite resin evaluated was Filtek Z250 (3M Dental). The composite was filled into acrylic moulds that were randomly polymerized for 40 seconds by each of the light-emitting...

  20. Comparison of an interactive CD-based and traditional instructor-led Basic Life Support skills training for nurses.

    Science.gov (United States)

    Mardegan, Karen J; Schofield, Margot J; Murphy, Gregory C

    2015-08-01

    Basic Life Support (BLS) is a life-saving and fundamental skill in resuscitation. However, studies have reported limitations in BLS training outcomes for both health professional and lay populations, and noted the resource and time-intensive nature of traditional training approaches. This exploratory study evaluated the effectiveness of an interactive CD-based BLS training programme that included unsupervised manikin practice compared with a traditional instructor-led BLS training programme involving demonstration and supervised practice. A quasi-experimental post-test with follow-up design was used. The sample was comprised of two cohorts: Novice second-year undergraduate Nursing students (n=187) and Practising Nurses (n=107) in their first year of hospital employment. BLS skill outcomes were assessed at one week and again at eight weeks post training. No statistically significant differences were found between the CD and traditional instructor-led BLS training methods in BLS skills of Novice and Practising Nurses at one week and eight weeks post training. However, there was a decrement in skill between one week and eight weeks post-training across both groups and an overall low level of competence. The failure to find a difference between the CD-based BLS programme with unsupervised manikin practice and a resource-intensive traditional instructor-led BLS training programme may indicate equivalence of the programmes or, even study design limitations. It is concerning that competence displayed by trainees from both groups was less than optimal and suggests the need for renewed efforts to develop and evaluate BLS training programmes which can achieve high rates of competence with acceptable skill retention over time. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  1. Reliability based structural design

    NARCIS (Netherlands)

    Vrouwenvelder, A.C.W.M.

    2013-01-01

    According to ISO 2394, structures shall be designed, constructed and maintained in such a way that they are suited for their use during the design working life in an economic way. To fulfil this requirement one needs insight into the risk and reliability under expected and non-expected actions. A

  2. Structured nurse-led follow-up for patients after discharge from the intensive care unit: Prospective quasi-experimental study.

    Science.gov (United States)

    Jónasdóttir, Rannveig J; Jones, Christina; Sigurdsson, Gisli H; Jónsdóttir, Helga

    2018-03-01

    The aim of this study was to describe a structured 3-month nurse-led follow-up of patients after discharge from intensive care and measure its effects on health status. Patients requiring intensive care stay frequently have lengthy and incomplete recovery suggesting need for additional support. The effects of intensive care nurse-led follow-up have not been sufficiently elucidated. A prospective, quasi-experimental study of patients who received structured nurse-led follow-up from intensive care nurses after discharge from intensive care until 3 months afterwards. The control group received usual care. Of 574 patients assessed for eligibility, from November 2012 - May 2015, 168 were assigned to the experimental group (N = 73) and the control group (N = 75). Primary outcome was health status, measured with eight scales of Short Form-36v2, before the intensive care admission and at four time points until 12 months after intensive care. A mixed effect model tested differences between the groups over time. Criteria for Reporting Development and Evaluation of Complex Interventions 2 guideline, guided the reporting of the intervention. The structured nurse-led follow-up did not improve patients' health status compared with usual care (mixed effect model, p = .078-.937). The structured nurse-led follow-up did not reveal an effect on the intensive care patients studied. Further examination of intensive care nurse-led follow-up is needed, taking into account the heterogeneity of the patient population, variations in length of ward stay, patients' health care needs during the first week at home after discharge from general ward and health status before intensive care admission. © 2017 John Wiley & Sons Ltd.

  3. 71-Mbit/s ultraviolet-B LED communication link based on 8-QAM-OFDM modulation.

    Science.gov (United States)

    Sun, Xiaobin; Zhang, Zhenyu; Chaaban, Anas; Ng, Tien Khee; Shen, Chao; Chen, Rui; Yan, Jianchang; Sun, Haiding; Li, Xiaohang; Wang, Junxi; Li, Jinmin; Alouini, Mohamed-Slim; Ooi, Boon S

    2017-09-18

    A demonstration of ultraviolet-B (UVB) communication link is implemented utilizing quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM). The demonstration is based on a 294-nm UVB-light-emitting-diode (UVB-LED) with a full-width at half-maximum (FWHM) of 9 nm and light output power of 190 μW, at 7 V, with a special silica gel lens on top of it. A -3-dB bandwidth of 29 MHz was measured and a high-speed near-solar-blind communication link with a data rate of 71 Mbit/s was achieved using 8-QAM-OFDM at perfect alignment. 23.6 Mbit/s using 2-QAM-OFDM when the angle subtended by the pointing directions of the UVB-LED and photodetector (PD) is 12 degrees, thus establishing a diffuse-line-of-sight (LOS) link. The measured bit-error rate (BER) of 2.8 ×10 -4 and 2.4 ×10 -4 , respectively, are well below the forward error correction (FEC) criterion of 3.8 ×10 -3 . The demonstrated high data-rate OFDM-based UVB communication link paves the way for realizing high-speed non-line-of-sight free-space optical communications.

  4. White LED-based optical wireless link with improved transmission capacity using nonorthogonal multiamplitude phase frequency modulation

    Science.gov (United States)

    Won, Yong-Yuk; Yoon, Sang Min; Seo, Dongsun

    2017-06-01

    A nonorthogonal amplitude, phase, and frequency modulation (APFM) technique that can increase the transmission capacity of an optical wireless link based on white light-emitting diode (LED) is proposed. It is implemented by the simultaneous use of nonorthogonal frequency shift keying (FSK) and quadrature amplitude modulation (QAM). A white LED-based wireless link using a 64-APFM scheme is constructed to experimentally verify the proposed technique, where the 64-APFM scheme is implemented by the combination of nonorthogonal 4-FSK and 16-QAM. Two more bits per symbol are transmitted using the proposed scheme with the same bandwidth of QAM. No intercarrier interference effect is observed at the 0.02-% frequency spacing (0.001 MHz) for the used RF carrier (5 MHz) because the correlation between the received 64-APFM signal and only one carrier at a time is accomplished with the help of digital signal processing. 6-Mbit/s (1-Msymbol/s) data are successfully transmitted through an optical wireless channel with a limited bandwidth of 1 MHz. This indicates that six bits per symbol can be transmitted using the proposed APFM technique at the same physical bandwidth as 16-QAM.

  5. 71-Mbit/s ultraviolet-B LED communication link based on 8-QAM-OFDM modulation

    KAUST Repository

    Sun, Xiaobin

    2017-09-14

    A demonstration of ultraviolet-B (UVB) communication link is implemented utilizing quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM). The demonstration is based on a 294-nm UVB-light-emitting-diode (UVB-LED) with a full-width at half-maximum (FWHM) of 9 nm and light output power of 190 μW, at 7 V, with a special silica gel lens on top of it. A −3-dB bandwidth of 29 MHz was measured and a high-speed near-solar-blind communication link with a data rate of 71 Mbit/s was achieved using 8-QAM-OFDM at perfect alignment. 23.6 Mbit/s using 2-QAM-OFDM when the angle subtended by the pointing directions of the UVB-LED and photodetector (PD) is 12 degrees, thus establishing a diffuse-line-of-sight (LOS) link. The measured bit-error rate (BER) of 2.8 × 10−4 and 2.4 × 10−4, respectively, are well below the forward error correction (FEC) criterion of 3.8 × 10−3. The demonstrated high data-rate OFDM-based UVB communication link paves the way for realizing high-speed non-line-of-sight free-space optical communications.

  6. Development of AlGaN-based deep-ultraviolet (DUV) LEDs focusing on the fluorine resin encapsulation and the prospect of the practical applications

    Science.gov (United States)

    Hirano, Akira; Nagasawa, Yosuke; Ippommatsu, Masamichi; Aosaki, Ko; Honda, Yoshio; Amano, Hiroshi; Akasaki, Isamu

    2016-09-01

    AlGaN-based LEDs are expected to be useful for sterilization, deodorization, photochemical applications such as UV curing and UV printing, medical applications such as phototherapy, and sensing. Today, it has become clear that efficient AlGaN-based LED dies are producible between 355 and 250 nm with an external quantum efficiency (EQE) of 3% on flat sapphire. These dies were realized on flat sapphire without using a special technique, i.e., reduction in threading dislocation density or light extraction enhancement techniques such as the use of a photonic crystal or a patterned sapphire substrate. Despite the limited light extraction efficiency of about 8% owing to light absorption at a thick p-GaN contact layer, high EQEs of approximately 6% has been reproducible between 300 and 280 nm without using special techniques. Moreover, an EQE of 3.9% has been shown at 271 nm, despite the smaller current injection efficiency (CIE). The high EQEs are thought to correspond to the high internal quantum efficiency (IQE), indicating a small room for improving IQE. Accordingly, resin encapsulation on a simple submount is strongly desired. Recently, we have succeeded in demonstrating fluorine resin encapsulation on a ceramic sheet (chip-on-board, COB) that is massproducible. Furthermore, the molecular structure of a resin with a durability of more than 10,000 h is explained in this paper from the photochemical viewpoint. Thus, the key technologies of AlGaN-based DUV-LEDs having an EQE of 10% within a reasonable production cost have been established. The achieved efficiency makes AlGaN-based DUVLEDs comparable to high-pressure mercury lamps.

  7. The characterization of an economic and portable LED-based photoacoustic imaging system to facilitate molecular imaging

    Directory of Open Access Journals (Sweden)

    Ali Hariri

    2018-03-01

    Full Text Available Photoacoustic imaging (PAI is a non-invasive, high-resolution hybrid imaging modality that combines optical excitation and ultrasound detection. PAI can image endogenous chromophores (melanin, hemoglobin, etc. and exogenous contrast agents in different medical applications. However, most current equipment uses sophisticated and complicated OPO lasers with tuning and stability features inconsistent with broad clinical deployment. As the number of applications of PAI in medicine increases, there is an urgent need to make the imaging equipment more compact, portable, and affordable. Here, portable light emitting diode – based photoacoustic imaging (PLED-PAI was introduced and characterized in terms of system specifications, light source characterizations, photoacoustic spatial/temporal resolution, and penetration. The system uses two LED arrays attached to the sides of a conventional ultrasound transducer. The LED pulse repetition rate is tunable between 1 K Hz, 2 K Hz, 3 K Hz, and 4 K Hz. The axial resolution was 0.268 mm, and the lateral resolution was between 0.55 and 0.59 mm. The system could detect optical absorber (pencil lead at a depth of 3.2 cm and the detection limits of indocyanine green (ICG and methylene blue (MB were 9 μM and 0.78 mM. In vivo imaging of labeled human mesenchymal stem cells was achieved to confirm compatibility with small animal imaging. The characterization we report here may have value to other groups evaluating commercially available photoacoustic imaging equipment. Keywords: Portable photoacoustic imaging, LED, Optoacoustic imaging, Molecular imaging

  8. Surface plasmon enhanced LED

    OpenAIRE

    Vučković, Jelena; Lončar, Marko; Painter, Oskar; Scherer, Axel

    2000-01-01

    Summary form only given. We designed and fabricated an LED based on a thin semiconductor membrane (λ/2) with silver mirrors. A large spontaneous emission enhancement and a high modulation speed are obtainable due to the strong localization of the electromagnetic field in the microcavity. The coupling to surface plasmon modes which are subsequently scattered out by means of a grating is used to improve the extraction efficiency of the LED. The bottom mirror is thick and unpatterned. The top mi...

  9. Synthesis, characteristics and luminescent properties of a new Tb(III) ternary complex applied in near UV-based LED

    Science.gov (United States)

    Sun, Naiqun; Li, Liping; Yang, Yamin; Zhang, Aiqin; Jia, Husheng; Liu, Xuguang; Xu, Bingshe

    2015-11-01

    A novel Tb(III) ternary complex, Tb(p-BBA)3UA, was synthesized with 4-benzoylbenzoic acid (p-BBA) as primary ligand and undecylenic acid (UA) as reactive ligand. Tb(III) complex exhibits high thermal stability and wide and strong excitation bands from 310 nm to 400 nm when monitored at 543 nm, which matches well with the 365 nm UV chip. The complex displays Tb(III) characteristic peaks at 488, 543, 584 and 619 nm under the excitation of 365 nm UV-light. The intramolecular energy transfer process was also discussed. Meanwhile, the complex has longer fluorescence lifetime (1.317 ms) and higher quantum yield (44.8%). When used in LED with 365 nm UV chip (power efficiency is 17.3 lm/W), the complex still maintained its qualified luminescent performance. All the results indicate that Tb(p-BBA)3UA can be applied as a green component for fabrication of near UV-based white LED.

  10. Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units

    Directory of Open Access Journals (Sweden)

    Sayed-Mostafa Mousavinasab

    2014-08-01

    Full Text Available Objectives Light-curing of resin-based materials (RBMs increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs of three different RBMs using quartz tungsten halogen (QTH and light-emitting diode (LED units (LCUs. Materials and Methods Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12 during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey, a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE, and a giomer (Beautifil II, Shofu GmbH, was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. Results The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05. Conclusions Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

  11. Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units.

    Science.gov (United States)

    Mousavinasab, Sayed-Mostafa; Khoroushi, Maryam; Moharreri, Mohammadreza; Atai, Mohammad

    2014-08-01

    Light-curing of resin-based materials (RBMs) increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs) of three different RBMs using quartz tungsten halogen (QTH) and light-emitting diode (LED) units (LCUs). Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12) during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey), a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE), and a giomer (Beautifil II, Shofu GmbH), was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05). Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

  12. Practical, reliable and inexpensive assay of lycopene in tomato products based on the combined use of light emitting diode (LED) and the optothermal window

    NARCIS (Netherlands)

    Bicanic, D.D.; Cuypers, R.; Luterotti, S.; Sporec, M.; Zoppi, A.; Vugec, J.

    2008-01-01

    Light emitting diode (LED) combined with the concept of optothermal window (OW) is proposed as a new approach (LED-OW) to detect lycopene in a wide range of tomato-based products (tomato juice, tomato ketchup, tomato passata and tomato puree). Phytonutrient lycopene is a dominant antioxidant in

  13. Degree of conversion and microhardness of TPO-containing resin-based composites cured by polywave and monowave LED units.

    Science.gov (United States)

    Santini, Ario; Miletic, Vesna; Swift, Michael D; Bradley, Mark

    2012-07-01

    To determine the degree of conversion (DC) and Knoop microhardness (KHN) of resin-based composites (RBCs) containing trimethylbenzoyl-diphenylphosphine oxide (TPO) cured by polywave or monowave LED light-curing units (LCUs). Three groups (each n = 5) of Tetric EvoCeram (Ivoclar Vivadent), Vit-l-escence (Ultradent) and Herculite XRV Ultra (Kerr) were prepared in Teflon moulds (5mm in diameter and 2mm thick) and cured with polywave Bluephase(®) G2 (Ivoclar Vivadent), polywave Valo (Ultradent) or monowave Bluephase(®) (Ivoclar Vivadent; control) resulting in 9 groups. DC and KHN were determined using micro-Raman spectroscopy and Knoop microhardness, respectively. High-performance liquid chromatography and nuclear magnetic resonance spectroscopy were used to confirm the presence or absence of TPO in the three uncured materials. Data were statistically analysed using two-way and one-way ANOVA and DC and KHN were correlated using Pearson's correlation (α = 0.05). TPO was confirmed in Tetric EvoCeram and Vit-l-escence but not in Herculite XRV Ultra. All three LCUs produced comparable KHN for Tetric EvoCeram and Herculite XRV Ultra (p > 0.05). Both polywave LCUs resulted in significantly higher KHN for Vit-l-escence and higher DC in Tetric EvoCeram and Vit-l-escence than the monowave Bluephase(®) (p TPO-containing RBCs, but not in Herculite XRV Ultra. DC and KHN were linearly correlated in all three RBCs. Vit-l-escence showed the highest DC and KHN of the three materials tested. The use of polywave LEDs significantly improves both the DC and KHN of materials which contain TPO. This should be taken into account when curing bleached shades of RBCs even if the manufacturers do not indicate the presence of TPO in their materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. A trial-based economic evaluation of 2 nurse-led disease management programs in heart failure.

    Science.gov (United States)

    Postmus, Douwe; Pari, Anees A Abdul; Jaarsma, Tiny; Luttik, Marie Louise; van Veldhuisen, Dirk J; Hillege, Hans L; Buskens, Erik

    2011-12-01

    Although previously conducted meta-analyses suggest that nurse-led disease management programs in heart failure (HF) can improve patient outcomes, uncertainty regarding the cost-effectiveness of such programs remains. To compare the relative merits of 2 variants of a nurse-led disease management program (basic or intensive support by a nurse specialized in the management of patients with HF) against care as usual (routine follow-up by a cardiologist), a trial-based economic evaluation was conducted alongside the COACH study. In terms of costs per life-year, basic support was found to dominate care as usual, whereas the incremental cost-effectiveness ratio between intensive support and basic support was found to be equal to €532,762 per life-year; in terms of costs per quality-adjusted life-year (QALY), basic support was found to dominate both care as usual and intensive support. An assessment of the uncertainty surrounding these findings showed that, at a threshold value of €20,000 per life-year/€20,000 per QALY, basic support was found to have a probability of 69/62% of being optimal against 17/30% and 14/8% for care as usual and intensive support, respectively. The results of our subgroup analysis suggest that a stratified approach based on offering basic support to patients with mild to moderate HF and intensive support to patients with severe HF would be optimal if the willingness-to-pay threshold exceeds €45,345 per life-year/€59,289 per QALY. Although the differences in costs and effects among the 3 study groups were not statistically significant, from a decision-making perspective, basic support still had a relatively large probability of generating the highest health outcomes at the lowest costs. Our results also substantiated that a stratified approach based on offering basic support to patients with mild to moderate HF and intensive support to patients with severe HF could further improve health outcomes at slightly higher costs. Copyright

  15. Perceived barriers and facilitators to Risk Based Monitoring in academic-led clinical trials: a mixed methods study.

    Science.gov (United States)

    Hurley, Caroline; Sinnott, Carol; Clarke, Mike; Kearney, Patricia; Racine, Emmy; Eustace, Joseph; Shiely, Frances

    2017-09-11

    In November 2016, the ICH published a requirement for sponsors to develop a systematic, prioritised, risk-based approach to monitoring clinical trials. This approach is more commonly known as risk-based monitoring (RBM). However, recent evidence suggests that a 'gold standard', validated approach to RBM does not exist and it is unclear how sponsors will introduce RBM into their organisations. A first step needed to inform the implementation of RBM is to explore academic trialists' readiness and ability to perform RBM. The aim of this paper is to identify the attitudes and perceived barriers and facilitators to the implementation of RBM in academic-led clinical trials in Ireland. This is a mixed-methods, explanatory sequential design, with quantitative survey followed by semistructured interviews. Academic clinical researchers (N = 132) working in Ireland were surveyed to examine their use and perceptions of RBM. A purposive sample of survey participants (n = 22) were then interviewed to gain greater insight into the quantitative findings. The survey and interview data were merged to generate a list of perceived barriers and facilitators to RBM implementation, with suggestions for, and solutions to, these issues. Survey response rate was 49% (132/273). Thirteen percent (n = 18) of responders were not familiar with the term risk-based monitoring and less than a quarter of respondents (21%, n = 28) had performed RBM in a clinical trial. Barriers to RBM implementation included lack of RBM knowledge/training, increased costs caused by greater IT demands, increased workload for trial staff and lack of evidence to support RBM as an effective monitoring approach. Facilitators included participants' legal obligation to perform RBM under the new ICH-GCP guidelines, availability of RBM guidance and perception of cost savings by performing RBM in future trials. The results of this study demonstrate a need for training and regulatory-endorsed guidelines to

  16. Specific LED-based red light photo-stimulation procedures improve overall sperm function and reproductive performance of boar ejaculates.

    Science.gov (United States)

    Yeste, Marc; Codony, Francesc; Estrada, Efrén; Lleonart, Miquel; Balasch, Sam; Peña, Alejandro; Bonet, Sergi; Rodríguez-Gil, Joan E

    2016-03-02

    The present study evaluated the effects of exposing liquid-stored boar semen to different red light LED regimens on sperm quality and reproductive performance. Of all of the tested photo-stimulation procedures, the best pattern consisted of 10 min light, 10 min rest and 10 min of further light (10-10-10 pattern). This pattern induced an intense and transient increase in the majority of motility parameters, without modifying sperm viability and acrosome integrity. While incubating non-photo-stimulated sperm at 37 °C for 90 min decreased all sperm quality parameters, this reduction was prevented when the previously-described light procedure was applied. This effect was concomitant with an increase in the percentage of sperm with high mitochondrial membrane potential. When sperm were subjected to 'in vitro' capacitation, photo-stimulation also increased the percentage of sperm with capacitation-like changes in membrane structure. On the other hand, treating commercial semen doses intended for artificial insemination with the 10-10-10 photo-stimulation pattern significantly increased farrowing rates and the number of both total and live-born piglets for parturition. Therefore, our results indicate that a precise photo-stimulation procedure is able to increase the fertilising ability of boar sperm via a mechanism that could be related to mitochondrial function.

  17. A trial-based economic evaluation of 2 nurse-led disease management programs in heart failure

    NARCIS (Netherlands)

    Postmus, Douwe; Pari, Anees A. Abdul; Jaarsma, Tiny; Luttik, Marie Louise; van Veldhuisen, Dirk J.; Hillege, Hans L.; Buskens, Erik

    2011-01-01

    Background Although previously conducted meta-analyses suggest that nurse-led disease management programs in heart failure (HF) can improve patient outcomes, uncertainty regarding the cost-effectiveness of such programs remains. Methods To compare the relative merits of 2 variants of a nurse-led

  18. Has the conduct-based approach to competition law in South Africa led to consistent interpretations of harm to competition?

    Directory of Open Access Journals (Sweden)

    Ryan Hawthorne

    2012-10-01

    Full Text Available The Competition Act and certain recent decisions by the competition authorities are examined here to assess the extent to which South Africa’s conduct-based approach to competition law has led to consistent outcomes in the assessment of effects on competition. This has not been the case in the assessment of anti-competitive effects among customers or resellers when a supplier accused of an anti-competitive action does not compete with its customers. An anti-competitive effect among customers or resellers is treated as anti-competitive when it arises from some form of conduct, such as price discrimination. However, it is not seen as anti-competitive when it arises from a refusal to supply, for example. Possible reasons for South Africa’s conduct-based approach and this inconsistent outcome in the assessment of competition among customers and resellers, including the economic foundations of the relevant approaches and their relationship with competition law in other jurisdictions, are assessed.

  19. Community led total sanitation for community based disaster risk reduction: A case for non-input humanitarian relief

    Directory of Open Access Journals (Sweden)

    Daniel H. Mlenga

    2016-01-01

    Full Text Available Sanitation related diseases have become endemic in southern Africa resulting in increased sanitation and hygiene morbidity and mortality. The region has experienced 318 400 cases of cholera and diarrhoea outbreaks between 2006 and 2012. There is insufficient financing for sanitation and hygiene activities, as people lack basic sanitation services, they engage in open defecation, the primary cause of faecal oral disease transmission. This study investigated Community Led Total Sanitation (CLTS, subsidy free, community based disaster risk reduction approach, for open defecation reduction, in four constituencies in Swaziland. Data collected from households, through a knowledge, attitudes and practices (KAP survey illustrated that with appropriate training, involvement of traditional and community leaders, CLTS minimises open defecation. There is need of participatory rural appraisal through regular community monitoring and feedback meetings, as the disgust generated especially for women and youth, through the meetings, as well as group dynamics, steer the sustained construction and use of sanitation facilities. Lack of coordination between Non-Governmental Organisations (NGOs leads to slow improvement of sanitation coverage, wherein the same communities are promoting CLTS and others are promoting Subsidy Based Sanitation Intervention (SBSI which involves subsidies. It is recommended that there be coordination between partners for harmonisation of messages and an integration of the CLTS and SBSI approaches.

  20. Epitaxial growth and properties of AlGaN-based UV-LEDs on Si(111) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Saengkaew, Phannee

    2010-07-08

    An increasing demand for bright and efficient ultraviolet light emitting diodes (UVLEDs) is generated by numerous applications such as biochemical sensors, purification and sterilization, and solid-state white lighting. Al{sub x}Ga{sub 1-x}N is a promising material to develop UVLEDs due to the direct wide-bandgap material for emission wavelengths in the UV range and the capability of n- and p-type doping. To develop UV-LEDs on Si substrates is very interesting for low-cost UV-light sources since the Si substrate is available at low cost, in large-diameter size enabling the integration with well-known Si electronics. This work presents the first crack-free AlGaN-based UV-LEDs on Si(111) substrates by MOVPE growth. This AlGaN-based UV-LED on Si(111) substrate consists of Al{sub 0.1}Ga{sub 0.9}N:Si layers on LT-AlN/HT-AlN SL buffer layers and an active layer of GaN/Al{sub 0.1}Ga{sub 0.9}N MQWs followed by Mg-doped (GaN/Al{sub 0.1}Ga{sub 0.9}N) superlattices and GaN:Mg cap layers. It yields a {proportional_to}350 nm UV electroluminescence at room temperature and a turn-on voltage in a range of 2.6-3.1 V by current-voltage (I-V) measurements. The novel LT-AlN/HT-AlN superlattice buffer layers efficiently improve the crystalline quality of Al{sub x}Ga{sub 1-x}N layers and compensate a thermal tensile strain in Al{sub x}Ga{sub 1-x}N layers after cooling as observed by in-situ curvature measurements. The dislocation density could be reduced from 8.4 x 10{sup 10} cm{sup -2} in the AlN-based SLs to 1.8 x 10{sup 10} cm{sup -2} in the Al{sub 0.1}Ga{sub 0.9}N layers as determined by cross-sectional transmission electron microscopy (TEM) measurements. Crack-free Al{sub x}Ga{sub 1-x}N layers grown on these LT-AlN/HT-AlN superlattices with 0.05{<=}x{<=} 0.65 are achieved on Si substrates with good crystalline, optical, and electrical properties. The best crystalline quality of Al{sub 0.1}Ga{sub 0.9}N is obtained with {omega}-FWHMs of the (0002) and (10-10) reflections of

  1. Study on method to simulate light propagation on tissue with characteristics of radial-beam LED based on Monte-Carlo method.

    Science.gov (United States)

    Song, Sangha; Elgezua, Inko; Kobayashi, Yo; Fujie, Masakatsu G

    2013-01-01

    In biomedical, Monte-carlo simulation is commonly used for simulation of light diffusion in tissue. But, most of previous studies did not consider a radial beam LED as light source. Therefore, we considered characteristics of a radial beam LED and applied them on MC simulation as light source. In this paper, we consider 3 characteristics of radial beam LED. The first is an initial launch area of photons. The second is an incident angle of a photon at an initial photon launching area. The third is the refraction effect according to contact area between LED and a turbid medium. For the verification of the MC simulation, we compared simulation and experimental results. The average of the correlation coefficient between simulation and experimental results is 0.9954. Through this study, we show an effective method to simulate light diffusion on tissue with characteristics for radial beam LED based on MC simulation.

  2. Plasma-based accelerator structures

    International Nuclear Information System (INIS)

    Schroeder, Carl B.

    1999-01-01

    Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas

  3. Violet-blue LEDs based on p-GaN/n-ZnO nanorods and their stability

    International Nuclear Information System (INIS)

    Jha, Shrawan; Qian, Jin-Cheng; Kutsay, Oleksandr; Kovac, Jaroslav Jr; Luan, Chun-Yan; Zapien, Juan Antonio; Zhang Wenjun; Lee, Shuit-Tong; Bello, Igor

    2011-01-01

    In this paper, we report a fabrication, characterization and stability study of p-GaN/n-ZnO nanorod heterojunction light-emitting devices (LEDs). The LEDs were assembled from arrays of n-ZnO vertical nanorods epitaxially grown on p-GaN. LEDs showed bright electroluminescence in blue (440 nm), although weaker violet (372 nm) and green-yellow (550 nm) spectral components were also observed. The device characteristics are generally stable and reproducible. The LEDs have a low turn-on voltage (∼5 V). The electroluminescence (EL) is intense enough to be noticed by the naked eye, at an injection current as low as ∼ 40 μA (2.1 x 10 -2 A cm -2 at 7 V bias). Analysis of the materials, electrical and EL investigations point to the role of a high quality of p-n nano-heterojunction which facilitates a large rectification ratio (320) and a stable reverse current of 2.8 μA (1.4 x 10 -3 A cm -2 at 5 V). Stability of EL characteristics was investigated in detail. EL intensity showed systematic degradation over a short duration when the LED was bias-stressed at 30 V. At smaller bias (<20 V) LEDs tend to show a stable and repeatable EL characteristic. Thus a simple low temperature solution growth method was successfully exploited to realize nanorod/film heterojunction LED devices with predictable characteristics.

  4. Light Emitting Diode (LED)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  5. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  6. Psychological recovery after intensive care: Outcomes of a long-term quasi-experimental study of structured nurse-led follow-up.

    Science.gov (United States)

    Jónasdóttir, Rannveig J; Jónsdóttir, Helga; Gudmundsdottir, Berglind; Sigurdsson, Gisli H

    2018-02-01

    To compare psychological recovery of patients receiving structured nurse-led follow-up and patients receiving usual care after intensive care discharge. Quasi-experimental study. Single centre, university hospital, mixed intensive care patient population. Symptoms of post-traumatic stress disorder, anxiety and depression measured three and four times over 12 months after intensive care discharge. Disturbing memories of the intensive care stay and psychological reactions (that one's life was in danger, threat to physical integrity, intense fear, helplessness, horror) three months after intensive care. A mixed effect model tested differences between the groups over time and regression model predicted post-traumatic stress at three months. The experimental group had significantly more symptoms of post-traumatic stress and anxiety than the control group over the 12 months. Patients from both groups had severe symptoms of post-traumatic stress. Patients with post-traumatic stress at three months had disturbing memories and psychological reactions. The structured nurse-led follow-up did not improve patients' measured outcomes of psychological recovery after intensive care. Patients with severe symptoms of post-traumatic stress are of concern. Emphasis needs to be placed on disturbing memories of the intensive care stay and psychological reactions when constructing intensive care nurse-led follow-up. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Structural Analysis of Plate Based Tensegrity Structures

    DEFF Research Database (Denmark)

    Hald, Frederik; Kirkegaard, Poul Henning; Damkilde, Lars

    2013-01-01

    Plate tensegrity structures combine tension cables with a cross laminated timber plate and can then form e.g. a roof structure. The topology of plate tensegrity structures is investigated through a parametric investigation. Plate tensegrity structures are investigated, and a method...

  8. A new bismuth-based coordination polymer as an efficient visible light responding photocatalyst under white LED irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ya-Jing; Zheng, Yue-Qing, E-mail: zhengyueqing@nbu.edu.cn; Wang, Jin-Jian; Zhou, Lin-Xia

    2017-02-15

    A new bismuth-based polymer, [Hbpe][Bi(Hpydc){sub 2}(pydc)]·H{sub 2}O (H{sub 2}pydc=pyridine-2,5-dicarboxylic acid, bpe=trans-bis(4-pyridyl) ethylene) has been hydrothermally synthesized. Transient photocurrent response and electrochemical impedance spectroscopy studies indicate that the synthesized polymer with efficient charge separation and transportation can be used as a potential photocatalyst. So we use it for the degradation of rhodamine B (RhB) dye wastewater under visible light. The comparative study on commercial Bi{sub 2}O{sub 3} shows [Hbpe][Bi(Hpydc){sub 2}(pydc)]·H{sub 2}O has the higher photocatalytic performance, with the degradation rate of 97% and 2% within 100 min for [Hbpe][Bi(Hpydc){sub 2}(pydc)]·H{sub 2}O and commercial Bi{sub 2}O{sub 3} respectively. Additionally, the five cycle reproducibility results of [Hbpe][Bi(Hpydc){sub 2}(pydc)]·H{sub 2}O implies that it can be used as a stable photocatalyst. - Graphical abstract: We report a new 1D coordination polymer [Hbpe][Bi(Hpydc){sub 2}(pydc)]·H{sub 2}O by a facile hydrothermal method. The Bi-CP shows good photoelectric property and photocatalytic activity for RhB degradation under visible white LED lamp irradiation. And the stability of the visible-light-responsive bismuth-based coordination polymer has also been examined. - Highlights: • A new Bi(III) coordination polymer is hydrothermally synthesized. • The Bi-CP shows good photoelectric and photocatalytic properties. • Bi-CP shows higher activity than the commercial Bi{sub 2}O{sub 3} for RhB degradation.

  9. Benefits and limitations of an employer-led, structured logbook to promote self-directed learning in the clinical workplace.

    Science.gov (United States)

    Dale, Vicki H M; Pierce, Stephanie E; May, Stephen A

    2013-01-01

    A structured logbook, consisting of a competency log and a learning contract, was designed and implemented as part of a two-week structured work placement for final-year veterinary students to help them become more self-directed in the workplace. The competency log encompassed 48 core skills and, along with the learning contract, was reviewed at the start and end of the placement. To assess their perceptions of the logbook in promoting self-directed learning, students and supervisors were asked to complete a questionnaire pre- and post-placement and to participate in focus groups (students) and interviews (supervisors) after the placement. The study found significant increases pre- to post-placement in students' perceived levels of competence in all 48 skills and their confidence in being self-directed. However, student attitudes toward the logbook significantly decreased in terms of it encouraging supervisors to take a clearly designed role in structuring learning and facilitating alignment of employer and student expectations. Although supervisors were generally positive about the logbook, some had not been able to review it with their students, which affected students' perceptions of the logbook's usefulness. Some supervisors felt they had not received enough training, and most, erroneously, believed the logbook to be an external research initiative rather than having been designed by the head of their own organization. This study demonstrated that a structured logbook may be useful in helping students become more self-directed; however, supervisor support for the logbook is critical. To facilitate this, supervisors require training and support from senior management.

  10. Nurse-led telephone-based follow-up of secondary prevention after acute coronary syndrome: One-year results from the randomized controlled NAILED-ACS trial

    OpenAIRE

    Huber, Daniel; Henriksson, Robin; Jakobsson, Stina; Mooe, Thomas

    2017-01-01

    Background. Secondary prevention after acute coronary syndrome (ACS) could reduce morbidity and mortality, but guideline targets are seldom reached. We hypothesized that nurse-led telephone- based intervention would increase adherence. Methods. The NAILED ACS trial is a prospective, controlled, randomized trial. Patients admitted for ACS at Ostersund hospital, Sweden, were randomized to usual follow-up by a general practitioner or a nurse-led intervention. The intervention comprised telephone...

  11. Comparative experimental and simulation studies of high-power AlGaN-based 353 nm ultraviolet flip-chip and top-emitting LEDs

    Science.gov (United States)

    Liu, Mengling; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Ding, Xinghuo

    2018-03-01

    Experimental and simulation studies of high-power AlGaN-based 353 nm ultraviolet (UV) flip-chip (FC) and top-emitting (TE) light-emitting diodes (LEDs) are performed here. To improve the optical and electrical properties of ultraviolet LEDs, we fabricate high-power FC-UV LEDs with Ta2O5/SiO2 distributed Bragg reflectors (DBRs) and a strip-shaped SiO2 current blocking layer (CBL). The reflectance of fourteen pairs of Ta2O5/SiO2 DBRs is 96.4% at 353 nm. The strip-shaped SiO2 CBL underneath the strip-shaped p-electrode can prevent the current concentrating in regions immediately adjacent to the p-electrode where the overlying opaque p-electrode metal layer absorbs the emitted UV light. Moreover, two-level metallization electrodes are used to improve current spreading. Our numerical results show that FC-UV LED has a more favorable current spreading uniformity than TE-UV LED. The light output power of 353 nm FC-UV LED was 23.22 mW at 350 mA, which is 24.7% higher than that of TE-UV LED.

  12. A randomized controlled trial to assess effectiveness of a nurse-led home-based heart failure management program

    Directory of Open Access Journals (Sweden)

    Mamata Rai

    2017-01-01

    Full Text Available Introduction: The burden of cardiovascular disease is increasing in India. It is a chronic condition, and poor management can increase the risk and frequency of acute episodes resulting in poor quality of life (QOL, frequent hospital admissions, and mortality. Disease management programs can improve medication adherence and patient's QOL. Objective: The aim of this study is to assess the effectiveness of nurse-led home-based heart failure management program (HOME-N. Materials and Methods: This randomized controlled trial was conducted among fifty outpatient heart failure (HF patients visiting a tertiary care hospital. The control group received usual routine care, whereas the experimental group received HOME-N, which included formal health teaching, a HF checklist (Hriday card, telemonitoring of vital parameters (blood pressure, heart rate, and weight weekly through a mobile application named as “Dhadkan” and telephonic follow-up for 3 months. Kansas City Cardiomyopathy Questionnaire (KCCQ and adherence to refills and medications scale were used to assess QOL and drug adherence, respectively, in the study patients. The outcome measures were the QOL, drug compliance, hospitalization, and mortality rate. Results: At baseline, the demographic and morbidity profile, and QOL and drug compliance scores of both groups were comparable. After intervention, the QOL domain score of KCCQ as well as drug compliance improved significantly both within the experimental group (P = 0.001, P = 0.001 and as compared to control group (P = 0.001, P = 0.004, respectively. Conclusion: The HOME-N was significantly effective in improving QOL and drug compliance in HF patients.

  13. Violet-blue LEDs based on p-GaN/n-ZnO nanorods and their stability.

    Science.gov (United States)

    Jha, Shrawan; Qian, Jin-Cheng; Kutsay, Oleksandr; Kovac, Jaroslav; Luan, Chun-Yan; Zapien, Juan Antonio; Zhang, Wenjun; Lee, Shuit-Tong; Bello, Igor

    2011-06-17

    In this paper, we report a fabrication, characterization and stability study of p-GaN/n-ZnO nanorod heterojunction light-emitting devices (LEDs). The LEDs were assembled from arrays of n-ZnO vertical nanorods epitaxially grown on p-GaN. LEDs showed bright electroluminescence in blue (440 nm), although weaker violet (372 nm) and green-yellow (550 nm) spectral components were also observed. The device characteristics are generally stable and reproducible. The LEDs have a low turn-on voltage (∼5 V). The electroluminescence (EL) is intense enough to be noticed by the naked eye, at an injection current as low as ∼ 40 µA (2.1 × 10(-2) A cm(-2) at 7 V bias). Analysis of the materials, electrical and EL investigations point to the role of a high quality of p-n nano-heterojunction which facilitates a large rectification ratio (320) and a stable reverse current of 2.8 µA (1.4 × 10(-3) A cm(-2) at 5 V). Stability of EL characteristics was investigated in detail. EL intensity showed systematic degradation over a short duration when the LED was bias-stressed at 30 V. At smaller bias (devices with predictable characteristics.

  14. 4.5-Gb/s RGB-LED based WDM visible light communication system employing CAP modulation and RLS based adaptive equalization.

    Science.gov (United States)

    Wang, Yiguang; Huang, Xingxing; Tao, Li; Shi, Jianyang; Chi, Nan

    2015-05-18

    Inter-symbol interference (ISI) is one of the key problems that seriously limit transmission data rate in high-speed VLC systems. To eliminate ISI and further improve the system performance, series of equalization schemes have been widely investigated. As an adaptive algorithm commonly used in wireless communication, RLS is also suitable for visible light communication due to its quick convergence and better performance. In this paper, for the first time we experimentally demonstrate a high-speed RGB-LED based WDM VLC system employing carrier-less amplitude and phase (CAP) modulation and recursive least square (RLS) based adaptive equalization. An aggregate data rate of 4.5Gb/s is successfully achieved over 1.5-m indoor free space transmission with the bit error rate (BER) below the 7% forward error correction (FEC) limit of 3.8x10(-3). To the best of our knowledge, this is the highest data rate ever achieved in RGB-LED based VLC systems.

  15. Evaluating Student Motivation in Organic Chemistry Courses: Moving from a Lecture-Based to a Flipped Approach with Peer-Led Team Learning

    Science.gov (United States)

    Liu, Yujuan; Raker, Jeffrey R.; Lewis, Jennifer E.

    2018-01-01

    Academic Motivation Scale-Chemistry (AMS-Chemistry), an instrument based on the self-determination theory, was used to evaluate students' motivation in two organic chemistry courses, where one course was primarily lecture-based and the other implemented flipped classroom and peer-led team learning (Flip-PLTL) pedagogies. Descriptive statistics…

  16. On the application of CaF2:Eu and SrF2:Eu phosphors in LED based phototherapy lamp

    Science.gov (United States)

    Belsare, P. D.; Moharil, S. V.; Joshi, C. P.; Omanwar, S. K.

    2013-06-01

    In the last few years the interest of scientific community has been increased towards solid state lighting based on LEDs because of their superior advantages over the conventional fluorescent lamps. As the GaN based LEDs are easily available efforts of the researchers are now on making the new phosphors which are excitable in the near UV region (360-400nm) for solid state lighting. This paper reports the photoluminescence characteristics of CaF2:Eu and SrF2:Eu phosphor prepared by wet chemical method. The violet emission of these phosphors with near UV excitation can be useful in making a phototherapy lamp based on LEDs for treating various skin diseases like acne vulgaris and hyperbilirubinemia.

  17. Comparison of instructor-led automated external defibrillation training and three alternative DVD-based training methods

    NARCIS (Netherlands)

    de Vries, Wiebe; Turner, Nigel M.; Monsieurs, Koenraad G.; Bierens, Joost J. L. M.; Koster, Rudolph W.

    2010-01-01

    Background: Self-directed BLS-training, using a personal training manikin with video has been shown to be as effective as instructor-led training. This has not previously been investigated for AED-training. Materials and methods: This prospective, randomized study with a non-inferiority design

  18. A Light-Emitting Diode- (LED-) Based Absorption Sensor for Simultaneous Detection of Carbon Monoxide and Carbon Dioxide.

    Science.gov (United States)

    Thurmond, Kyle; Loparo, Zachary; Partridge, William; Vasu, Subith S

    2016-06-01

    A sensor was developed for simultaneous measurements of carbon monoxide (CO) and carbon dioxide (CO2) fluctuations in internal combustion engine exhaust gases. This sensor utilizes low-cost and compact light-emitting diodes (LEDs) that emit in the 3-5 µm wavelength range. An affordable, fast response sensor that can measure these gases has a broad application that can lead to more efficient, fuel-flexible engines and regulation of harmful emissions. Light emission from LEDs is spectrally broader and more spatially divergent when compared to that of lasers, which presented many design challenges. Optical design studies addressed some of the non-ideal characteristics of the LED emissions. Measurements of CO and CO2 were conducted using their fundamental absorption bands centered at 4.7 µm and 4.3 µm, respectively, while a 3.6 µm reference LED was used to account for scattering losses (due to soot, window deposits, etc.) common to the three measurement LEDs. Instrument validation and calibration was performed using a laboratory flow cell and bottled-gas mixtures. The sensor was able to detect CO2 and CO concentration changes as small as 30 ppm and 400 ppm, respectively. Because of the many control and monitor species with infra-red absorption features, which can be measured using the strategy described, this work demonstrates proof of concept for a wider range of fast (250 Hz) and low-cost sensors for gas measurement and process monitoring. © The Author(s) 2016.

  19. Reliability Based Ship Structural Design

    DEFF Research Database (Denmark)

    Dogliani, M.; Østergaard, C.; Parmentier, G.

    1996-01-01

    This paper deals with the development of different methods that allow the reliability-based design of ship structures to be transferred from the area of research to the systematic application in current design. It summarises the achievements of a three-year collaborative research project dealing...... with developments of models of load effects and of structural collapse adopted in reliability formulations which aim at calibrating partial safety factors for ship structural design. New probabilistic models of still-water load effects are developed both for tankers and for containerships. New results are presented...... of non-linear wave induced load effects and the corresponding long-term formulations. Methods to combine linear and non-linear components of wave induced load effects have been developed and checked by alternative methods.These improved models were used for the reliability assessment of the primary hull...

  20. From carbon to light. A new framework for estimating greenhouse gas emissions reductions from replacing fuel-based lighting with LED systems

    Energy Technology Data Exchange (ETDEWEB)

    Mills, E. [Lawrence Berkeley National Laboratory LBNL, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Jacobson, A. [Office of Policy and International Affairs, US Department of Energy, 1000 Independence Avenue SW, Washington, DC 20585 (United States)

    2011-11-15

    There is considerable well-intended, yet wishful anticipation about reducing greenhouse gas emissions by replacing fuel-based lighting in the developing world with grid-independent light-emitting diode (LED) lighting systems. Most estimates gloss over important practical realities that stand to erode a genuinely significant potential. The Clean Development Mechanism (CDM) is the leading system for quantifying the benefits of such projects in developing countries and embodying them in a market-based platform for trading carbon credits. However, compliance with methodologies for highly decentralized, small-scale energy saving projects currently employed in the CDM is viewed by developers of as onerous, time-consuming, and costly. In recognition of the problem, the CDM has recently placed priority on improved methodologies for estimating carbon dioxide reductions from displacement of fuel-based lighting with energy-efficient alternatives. The over-arching aim is to maintain environmental integrity without stifling sustainable emission-reduction projects and programs in the field. This article informs this process by laying out a new framework that shifts the analytical focus from highly costly yet narrow and uncertain baseline estimations to simplified methods based primarily on deemed values that focus on replacement lighting system quality and performance characteristics. The result - many elements of which have been adopted in a new methodology approved by the CDM - is more structured and rigorous than methodologies used for LED projects in the past and yet simpler to implement, i.e., entailing fewer transaction costs. Applying this new framework, we find that some off-grid lighting technologies can be expected to yield little or no emissions reductions, while well-designed ones, using products independently certified to have high quality and durability, can generate significant reductions. Enfolding quality assurance within the proposed framework will help stem

  1. Nurse-led telephone-based follow-up of secondary prevention after acute coronary syndrome: One-year results from the randomized controlled NAILED-ACS trial.

    Science.gov (United States)

    Huber, Daniel; Henriksson, Robin; Jakobsson, Stina; Mooe, Thomas

    2017-01-01

    Secondary prevention after acute coronary syndrome (ACS) could reduce morbidity and mortality, but guideline targets are seldom reached. We hypothesized that nurse-led telephone-based intervention would increase adherence. The NAILED ACS trial is a prospective, controlled, randomized trial. Patients admitted for ACS at Östersund hospital, Sweden, were randomized to usual follow-up by a general practitioner or a nurse-led intervention. The intervention comprised telephone follow-up after 1 month and then yearly with lifestyle counselling and titration of medications until reaching target values for LDL-C (Nurse-led telephone-based secondary prevention was significantly more efficient at improving LDL-C and diastolic BP levels than usual care. The effect of the intervention declined between 1 and 12 months. Further evaluation of the persistence to the intervention is needed.

  2. Marginal seal of composite resin restorations photo activated by L.E.D. and halogen-based light

    OpenAIRE

    Pineda Mejía, Martha Elena; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Terán Casafranca, Liliana Ángela; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Gloria Zevallos, Waldo Ernesto; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Cuadrao Zavaleta, Luis Alberto; Dpto. Acad. Ciencias Básicas. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.

    2014-01-01

    Objective: to compare in vitro the marginal seal degree of composite resin restorations photopolomerized with L.E.D light and conventional halogen light, was the objective of this research.It was used 20 healthy molars recently extracted, in each of them, standardized dimensions class V cavities were prepared in the buccal and palatal aspects. Both cavities were filled with nanoparticles composite resin, Filteck Z350 and Single Bond adhesive (3M). Vestibular restaurations were light cured usi...

  3. Assessing the Performance of LED-Based Flashlights Available in the Kenyan Off-Grid Lighting Market

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Jennifer; Jacobson, Arne; Mills, Evan

    2010-03-02

    Low cost rechargeable flashlights that use LED technology are increasingly available in African markets. While LED technology holds promise to provide affordable, high quality lighting services, the widespread dissemination of low quality products may make it difficult to realize this potential. This study includes performance results for three brands of commonly available LED flashlights that were purchased in Kenya in 2009. The performance of the flashlights was evaluated by testing five units for each of the three brands. The tests included measurements of battery capacity, time required to charge the battery, maximum illuminance at one meter, operation time and lux-hours from a fully charged battery, light distribution, and color rendering. All flashlights tested performed well below the manufacturers? rated specifications; the measured battery capacity was 30-50percent lower than the rated capacity and the time required to fully charge the battery was 6-25percent greater than the rated time requirement. Our analysis further shows that within each brand there is considerable variability in each performance indicator. The five samples within a single brand varied from each other by as much as 22percent for battery capacity measurements, 3.6percent for the number of hours required for a full charge, 23percent for maximum initial lux, 38percent for run time, 11percent for light distribution and by as much as 200percent for color rendering. Results obtained are useful for creating a framework for quality assurance of off-grid LED products and will be valuable for informing consumers, distributors and product manufacturers about product performance.

  4. Cost-effectiveness of a nurse-led internet-based vascular risk factor management programme : Economic evaluation alongside a randomised controlled clinical trial

    NARCIS (Netherlands)

    Greving, J. P.; Kaasjager, H. A H; Vernooij, J.W.P.; Hovens, M. M C; Wierdsma, J.; Grandjean, H. M H; Van Der Graaf, Y.; De Wit, G. A.; Visseren, F. L J

    2015-01-01

    Objective: To assess the cost-effectiveness of an internet-based, nurse-led vascular risk factor management programme in addition to usual care compared with usual care alone in patients with a clinical manifestation of a vascular disease. Design: Cost-effectiveness analysis alongside a randomised

  5. A 2 x 2 imaging MIMO system based on LED Visible Light Communications employing space balanced coding and integrated PIN array reception

    DEFF Research Database (Denmark)

    Li, Jiehui; Xu, Yinfan; Shi, Jianyang

    2016-01-01

    In this paper, we proposed a 2 x 2 imaging Multi-Input Multi-Output (MIMO)-Visible Light Communication (VLC) system by employing Space Balanced Coding (SBC) based on two RGB LEDs and integrated PIN array reception. We experimentally demonstrated 1.4-Gbit/s VLC transmission at a distance of 2.5 m...

  6. Design of a lighting system with high-power LEDs, large area electronics, and light management structure in the LUMENTILE European project

    Science.gov (United States)

    Carraro, L.; Simonetta, M.; Benetti, G.; Tramonte, A.; Capelli, G.; Benedetti, M.; Randone, E. M.; Ylisaukko-oja, A.; Keränen, K.; Facchinetti, T.; Giuliani, G.

    2017-02-01

    LUMENTILE (LUMinous ElectroNic TILE) is a project funded by the European Commission with the goal of developing a luminous tile with novel functionalities, capable of changing its color and interact with the user. Applications include interior/exterior tile for walls and floors covering, high-efficiency luminaries, and advertising under the form of giant video screens. High overall electrical efficiency of the tile is mandatory, as several millions of square meters are foreseen to be installed each year. Demand is for high uniformity of the illumination of the top tile surface, and for high optical extraction efficiency. These features are achieved by smart light management, using a new approach based on light guiding slab and spatially selective light extraction obtained using both diffusion and/or reflection from the top and bottom interfaces of the optical layer. Planar and edge configurations for the RGB LEDs are considered and compared. A square shape with side length from 20cm to 60cm is considered for the tiles. The electronic circuit layout must optimize the electrical efficiency, and be compatible with low-cost roll-to-roll production on flexible substrates. LED heat management is tackled by using dedicated solutions that allow operation in thermally harsh environment. An approach based on OLEDs has also been considered, still needing improvement on emitted power and ruggedness.

  7. Low Level Evidence Suggests That Librarian-Led Instruction in Evidence Based Practice is Effective Regardless of Instructional Model

    Directory of Open Access Journals (Sweden)

    Lindsay J. Alcock

    2017-06-01

    studies which included descriptive statistics and many also included inferential statistics intended to show significance. Differences between groups were assessed with parametric measures in 9 studies and non-parametric measures in 15 studies. Good to high statistical significance on at least 1 measurement was achieved in 23 studies. Given the absence of effect sizes, the level of differences between study groups could not be determined. Conclusion – Numerous pedagogical methods are used in librarian-led instruction in evidence based practice. However, there is a paucity of high level evidence and the literature suggests that no instructional method is demonstrated to be more effective than another.

  8. Program structure-based blocking

    Science.gov (United States)

    Bertolli, Carlo; Eichenberger, Alexandre E.; O'Brien, John K.; Sura, Zehra N.

    2017-09-26

    Embodiments relate to program structure-based blocking. An aspect includes receiving source code corresponding to a computer program by a compiler of a computer system. Another aspect includes determining a prefetching section in the source code by a marking module of the compiler. Yet another aspect includes performing, by a blocking module of the compiler, blocking of instructions located in the prefetching section into instruction blocks, such that the instruction blocks of the prefetching section only contain instructions that are located in the prefetching section.

  9. Evaluation of Uniformity and Glare Improvement with Low Energy Efficiency Losses in Street Lighting LED Luminaires Using Laser-Sintered Polyamide-Based Diffuse Covers

    Directory of Open Access Journals (Sweden)

    Alfonso Gago-Calderón

    2018-04-01

    Full Text Available Energy saving in street lighting is garnering more interest and has become a priority in municipal management. Therefore, LED luminaires are gradually becoming prevalent in our cities. Beyond their energy/economic saving potential, quality in public lighting installations concerns aspects such as uniformity and glare which must be maintained if not improved in any installation renewal project using this technology. The high light intensity generated in a discrete point in LED packages and its directional nature result in significant deficiencies in these last two parameters. To soften these effects, translucent covers are being used as one of the most common solutions with the drawback of significant light intensity losses. The objective of this paper is to evaluate the behavior of LED luminaire’s polyamide-based optical covers manufactured with a laser-sintered process. These are designed to improve glare and uniformity output, to minimize light output reductions, and to be industrially manufactured with no increment of cost for their lighting equipment compared to conventional transparent polycarbonate solutions. A laboratory and field lighting test study has been applied to different covers with the same LED lamp and luminaire to compare the performance of three different solutions built with different polymeric materials and with different light transmission surface textures. The photometric results have been observed and discussed to demonstrate the ability to significantly improve the lighting performance of LED luminaires—illuminance and uniformity levels and discomfort and disability glare indexes— using an improved optic cover.

  10. Reliability-based optimization of engineering structures

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2008-01-01

    The theoretical basis for reliability-based structural optimization within the framework of Bayesian statistical decision theory is briefly described. Reliability-based cost benefit problems are formulated and exemplitied with structural optimization. The basic reliability-based optimization prob...

  11. Vibration-based structural health monitoring of harbor caisson structure

    Science.gov (United States)

    Lee, So-Young; Lee, So-Ra; Kim, Jeong-Tae

    2011-04-01

    This study presents vibration-based structural health monitoring method in foundation-structure interface of harbor caisson structure. In order to achieve the objective, the following approaches are implemented. Firstly, vibration-based response analysis method is selected and structural health monitoring (SHM) technique is designed for harbor caisson structure. Secondly, the performance of designed SHM technique for harbor structure is examined by FE analysis. Finally, the applicability of designed SHM technique for harbor structure is evaluated by dynamic tests on a lab-scaled caisson structure.

  12. Nursing intensive care skills training: a nurse led, short, structured, and practical training program, developed and tested in a resource-limited setting.

    Science.gov (United States)

    De Silva, A Pubudu; Stephens, Tim; Welch, John; Sigera, Chathurani; De Alwis, Sunil; Athapattu, Priyantha; Dharmagunawardene, Dilantha; Olupeliyawa, Asela; de Abrew, Ashwini; Peiris, Lalitha; Siriwardana, Somalatha; Karunathilake, Indika; Dondorp, Arjen; Haniffa, Rashan

    2015-04-01

    To assess the impact of a nurse-led, short, structured training program for intensive care unit (ICU) nurses in a resource-limited setting. A training program using a structured approach to patient assessment and management for ICU nurses was designed and delivered by local nurse tutors in partnership with overseas nurse trainers. The impact of the course was assessed using the following: pre-course and post-course self-assessment, a pre-course and post-course Multiple Choice Questionnaire (MCQ), a post-course Objective Structured Clinical Assessment station, 2 post-course Short Oral Exam (SOE) stations, and post-course feedback questionnaires. In total, 117 ICU nurses were trained. Post-MCQ scores were significantly higher when compared with pre-MCQ (P electrocardiogram analysis). The course was highly rated by participants, with 98% believing that this was a useful experience. Nursing Intensive Care Skills Training was highly rated by participants and was effective in improving the knowledge of the participants. This sustainable short course model may be adaptable to other resource-limited settings. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Sex worker-led structural interventions in India: a case study on addressing violence in HIV prevention through the Ashodaya Samithi collective in Mysore.

    Science.gov (United States)

    Reza-Paul, Sushena; Lorway, Rob; O'Brien, Nadia; Lazarus, Lisa; Jain, Jinendra; Bhagya, M; Fathima Mary, P; Venukumar, K T; Raviprakash, K N; Baer, James; Steen, Richard

    2012-01-01

    Structural interventions have the capacity to improve the outcomes of HIV/AIDS interventions by changing the social, economic, political or environmental factors that determine risk and vulnerability. Marginalized groups face disproportionate barriers to health, and sex workers are among those at highest risk of HIV in India. Evidence in India and globally has shown that sex workers face violence in many forms ranging from verbal, psychological and emotional abuse to economic extortion, physical and sexual violence and this is directly linked to lower levels of condom use and higher levels of sexually transmitted infections (STIs), the most critical determinants of HIV risk. We present here a case study of an intervention that mobilized sex workers to lead an HIV prevention response that addresses violence in their daily lives. This study draws on ethnographic research and project monitoring data from a community-led structural intervention in Mysore, India, implemented by Ashodaya Samithi. Qualitative and quantitative data were used to characterize baseline conditions, community responses and subsequent outcomes related to violence. In 2004, the incidence of reported violence by sex workers was extremely high (> 8 incidents per sex worker, per year) but decreased by 84 per cent over 5 years. Violence by police and anti-social elements, initially most common, decreased substantially after a safe space was established for sex workers to meet and crisis management and advocacy were initiated with different stakeholders. Violence by clients, decreased after working with lodge owners to improve safety. However, initial increases in intimate partner violence were reported, and may be explained by two factors: (i) increased willingness to report such incidents; and (ii) increased violence as a reaction to sex workers' growing empowerment. Trafficking was addressed through the establishment of a self-regulatory board (SRB). The community's progressive response to violence

  14. Solution-Processed CuInS2-Based White QD-LEDs with Mixed Active Layer Architecture.

    Science.gov (United States)

    Wepfer, Svenja; Frohleiks, Julia; Hong, A-Ra; Jang, Ho Seong; Bacher, Gerd; Nannen, Ekaterina

    2017-03-29

    Colloidal quantum dots (QDs) are attractive candidates for future lighting technology. However, in contrast to display applications, the realization of balanced white lighting devices remains conceptually challenging. Here, we demonstrate two-component white light-emitting QD-LEDs with high color rendering indices (CRI) up to 78. The implementation of orange CuInS 2 /ZnS (CIS/ZnS) QDs with a broad emission and high quantum yield together with blue ZnCdSe/ZnS QDs in a mixed approach allowed white light emission with low blue QD content. The devices reveal only a small color drift in a wide operation voltage range. The correlated color temperature (CCT) could be adjusted between 2200 and 7200 K (from warm white to cold white) by changing the volume ratio between orange and blue QDs (1:0.5 and 1:2).

  15. Preparation and Performance of Poly(butyl fumarate-Based Material for Potential Application in LED Encapsulation

    Directory of Open Access Journals (Sweden)

    Liang Wang

    2017-02-01

    Full Text Available A UV-curable poly(butyl fumarate (PBF/poly(propylene fumarate-diacrylate (PPF-DA hybrid material with good performance for LED encapsulation is introduced in the paper. They have been prepared by radical polymerization using PBF and PPF-DA macromers with a UV curing system. PBF and PPF-DA were characterized by Fourier-transform infrared (FT-IR and H-nuclear magnetic resonance (1H NMR. The thermal behavior, optical and mechanical properties of the material were examined by thermogravimetric analysis (TGA, differential scanning calorimetry (DSC, ultraviolet-visible spectroscopy (UV–vis, and a material testing system mechanical testing machine, respectively. The results indicated that the hybrid material has a suitable refractive index (n = 1.537 and high transmittance (99.64% in visible range before/after thermal aging. With the increasing of the double bond ratio from 0.5 to 2, the water absorption ratios of the prepared encapsulation material were 1.22%, 1.87% and 2.88%, respectively. The mechanical property experiments showed that bonding strength was in the range of 1.86–3.40 MPa, tensile-shear strength ranged from 0.84 MPa to 1.57 MPa, and compression strength was in the range of 5.10–27.65 MPa. The cured PBF/PPF-DA hybrid material can be used as a light-emitting diode (LED encapsulant, owing to its suitable refractive index, high transparency, excellent thermal stability, lower water absorption, and good mechanical properties.

  16. Application of the EGM Method to a LED-Based Spotlight: A Constrained Pseudo-Optimization Design Process Based on the Analysis of the Local Entropy Generation Maps

    Directory of Open Access Journals (Sweden)

    Enrico Sciubba

    2011-06-01

    Full Text Available In this paper, the entropy generation minimization (EGM method is applied to an industrial heat transfer problem: the forced convective cooling of a LED-based spotlight. The design specification calls for eighteen diodes arranged on a circular copper plate of 35 mm diameter. Every diode dissipates 3 W and the maximum allowedtemperature of the plate is 80 °C. The cooling relies on the forced convection driven by a jet of air impinging on the plate. An initial complex geometry of plate fins is presented and analyzed with a commercial CFD code that computes the entropy generation rate. A pseudo-optimization process is carried out via a successive series of design modifications based on a careful analysis of the entropy generation maps. One of the advantages of the EGM method is that the rationale behind each step of the design process can be justified on a physical basis. It is found that the best performance is attained when the fins are periodically spaced in the radial direction.

  17. Light out-coupling from LEDs by means of metal nanoparticles; Lichtauskopplung aus LEDs mittels Metallnanoteilchen

    Energy Technology Data Exchange (ETDEWEB)

    Goehler, Tino

    2010-12-17

    The external quantum efficiency of light-emitting diodes (LEDs) based on Al- GaAs/InGaAlP is limited by total internal reflection because of the high refractive index (typically between 3 and 4) of the semiconductor. Metal nanoparticles (MNP) deposited on the surface of the LED can be used as dipole scatterers in order to enhance the emission of the LED. In this thesis, first, single gold nanoparticles of various sizes deposited on such an LED were investigated. A clear enhancement is detected as long as the dipole plasmon resonance of the particle is at a shorter wavelength than the LED emission. If the plasmon resonance coincides with the LED emission or is at a larger wavelength, the enhancement turns into suppression. Numerical simulations indicate that this latter effect is mainly caused by the particle quadrupole resonance producing extra absorption. Arrays of MNPs can be produced by a special mask technique called ''Fischer pattern nanolithography'' and manipulated in shape and size by additional steps. Originally, the MNPs produced by this technique are triangular in shape and turn out to suppress the LED emission. After transformation of the particles to spheres, a clear enhancement was detected. Light that would otherwise remain trapped inside the substrate is coupled out by resonant plasmonic scattering. Investigations on analogous structures on a transparent high-index material (GaP) indicate a stronger coupling between the particles than expected on the basis of literature data. (orig.)

  18. Silicone materials for LED packaging

    Science.gov (United States)

    Bahadur, Maneesh; Norris, Ann W.; Zarisfi, Afrooz; Alger, James S.; Windiate, Christopher C.

    2006-08-01

    Silicone based materials have attracted considerable attention from light emitting diode (LED) manufacturers for use as encapsulants and lenses for many high brightness LED (HB LED) devices. Currently silicones function in two key roles in HB LED devices, (1) as protective lenses and (2) stress relieving encapsulants for wire bond protection. The key attributes of silicones that make them attractive as light path materials for high brightness HB LEDs include their high transparency in the UV-visible region, controlled refractive index (RI), stable thermo-mechanical properties, and tuneable modulus from soft gels to hard resins. This paper will describe recent developments in moldable silicone hard resin materials. Progress on cavity moldable and liquid injection moldable (LIM) silicone compositions for discreet components is described. Also, an example of liquid injection overmolding is presented.

  19. Surface aspects of discolouration in Bisphenol A Polycarbonate (BPA-PC), used as lens in LED-based products

    Science.gov (United States)

    Yazdan Mehr, M.; van Driel, W. D.; Udono, H.; Zhang, G. Q.

    2014-11-01

    The surface-related reactions during discolouration of Bisphenol A Polycarbonate (BPA-PC), used as LED lens plates, under thermal stress are studied. X-ray photoelectron spectroscopy (XPS) has been used to monitor the changes in the surface chemistry of BPA-PC plates over a temperature range of 100-140 °C for a period up to 3000 h. Increasing time under thermal stress is associated with the discolouration, and increase in the yellowing index (YI) of PC plastic lens. The XPS results show that discolouration is associated with oxidation at the surface, finding a significant increase in the signal ratio O1s/C1s in the XPS spectra of degraded specimens. During thermal ageing, the Csbnd H concentration decreases and new oxide features Cdbnd O and Osbnd Cdbnd O form, with the latter being a support for oxidation at the surface being a major reaction during discolouration. Results also show that irradiation with blue light during thermal ageing accelerates the kinetics of discolouration and the increased O1s/C1s ratio in XPS spectra.

  20. Novel wearable-type biometric devices based on skin tissue optics with multispectral LED-photodiode matrix

    Science.gov (United States)

    Jo, Young Chang; Kim, Hae Na; Kang, Jae Hwan; Hong, Hyuck Ki; Choi, Yeon Shik; Jung, Suk Won; Kim, Sung Phil

    2017-04-01

    In this study, we examined the possibility of using a multispectral skin photomatrix (MSP) module as a novel biometric device. The MSP device measures optical patterns of the wrist skin tissue. Optical patterns consist of 2 × 8 photocurrent intensities of photodiode arrays, which are generated by optical transmission and diffuse reflection of photons from LED light sources with variable wavelengths into the wrist skin tissue. Optical patterns detected by the MSP device provide information on both the surface and subsurface characteristics of the human skin tissue. We found that in the 21 subjects we studied, they showed their unique characteristics, as determined using several wavelengths of light. The experimental results show that the best personal identification accuracy can be acquired using a combination of infrared light and yellow light. This novel biometric device, the MSP module, exhibited an excellent false acceptance rate (FAR) of 0.3% and a false rejection rate (FRR) of 0.0%, which are better than those of commercialized biometric devices such as a fingerprint biometric system. From these experimental results, we found that people exhibit unique optical patterns of their inner-wrist skin tissue and this uniqueness could be used for developing novel high-accuracy personal identification devices.

  1. LED-roulette : LED's vervangen balletje

    NARCIS (Netherlands)

    Goossens, P.

    2007-01-01

    Iedereen waagt wel eens een gokje, in een loterij of misschien ook in een casino. Wie droomt er immers niet van om op een gemakkelijke manier rijk te worden? Met de hier beschreven LED-roulette valt weliswaar weinig te winnen, maar het is wel een uitstekende manier om het roulettespel thuis te

  2. An instrument for measurements of BrO with LED-based Cavity-Enhanced Differential Optical Absorption Spectroscopy

    Science.gov (United States)

    Hoch, D. J.; Buxmann, J.; Sihler, H.; Pöhler, D.; Zetzsch, C.; Platt, U.

    2014-01-01

    The chemistry of the troposphere and specifically the global tropospheric ozone budget is affected by reactive halogen species such as bromine monoxide (BrO) or chlorine monoxide (ClO). Especially BrO plays an important role in the processes of ozone destruction, disturbance of NOx and HOx chemistry, oxidation of dimethyl sulfide (DMS), and the deposition of elementary mercury. In the troposphere BrO has been detected in polar regions, at salt lakes, in volcanic plumes, and in the marine boundary layer. For a better understanding of these processes, field measurements as well as reaction chamber studies are performed. In both cases instruments with high spatial resolution and high sensitivity are necessary. A Cavity-Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) instrument with an open path measurement cell was designed and applied. For the first time, a CE-DOAS instrument is presented using an UV LED in the 325-365 nm wavelength range. In laboratory studies, BrO as well as HONO, HCHO, O3, and O4 could be reliably determined at detection limits of 20 ppt for BrO, 9.1 ppb for HCHO, 970 ppt for HONO, and 91 ppb for O3, for five minutes integration time. The best detection limits were achieved for BrO (11 ppt), HCHO (5.1 ppb), HONO (490 ppt), and O3 (59 ppb) for integration times of 81 minutes or less. Comparison with established White system (WS) DOAS and O3 monitor measurements demonstrate the reliability of the instrument.

  3. Self-reported Impacts of LED Lighting Technology Compared to Fuel-based Lighting on Night Market Business Prosperity in Kenya

    Energy Technology Data Exchange (ETDEWEB)

    Johnstone, Peter; Jacobson, Arne; Mills, Evan; Mumbi, Maina

    2009-02-11

    The notion of"productive use" is often invoked in discussions about whether new technologies improve productivity or otherwise enhance commerce in developing-country contexts. It an elusive concept,especially when quantitative measures are sought. Improved and more energy efficient illumination systems for off-gridapplication--the focus of the Lumina Project--provide a case in which a significant productivity benefit can be imagined, given the importance of light to the successful performance of many tasks, and the very low quality of baseline illumination provided by flame-based source. This Research Note summarizes self-reported quantitative and qualitative impacts of switching to LED lighting technology on the prosperity of night-market business owners and operators. The information was gathered in the context of our 2008 market testing field work in Kenya?s Rift Valley Province, which was performed in the towns of Maai Mahiu and Karagita by Arne Jacobson, Kristen Radecsky, Peter Johnstone, Maina Mumbi, and others. Maai Mahiu is a crossroads town; provision of services to travelers and freight carriers is a primary income source for the residents. In contrast, the primary income for Karagita's residents is from work in the large, factory style flower farms on the eastern shores of Lake Naivasha that specialize in producing cut flowers for export to the European market. According to residents, both towns had populations of 6,000 to 8,000 people in June 2008. We focused on quantifying the economics of fuel-based and LED lighting technology in the context of business use by night market vendors and shop keepers. Our research activities with the business owners and operators included baseline measurement of their fuel-based lighting use, an initial survey, offering for sale data logger equipped rechargeable LED lamps, monitoring the adoption of the LED lamps, and a follow-up survey.

  4. Flower-Like Internal Emission Distribution of LEDs with Monolithic Integration of InGaN-based Quantum Wells Emitting Narrow Blue, Green, and Red Spectra.

    Science.gov (United States)

    Lee, Kwanjae; Choi, Ilgyu; Lee, Cheul-Ro; Chung, Tae-Hoon; Kim, Yoon Seok; Jeong, Kwang-Un; Chung, Dong Chul; Kim, Jin Soo

    2017-08-02

    We report a phosphor-free white light-emitting diodes (LED) realized by the monolithic integration of In 0.18 Ga 0.82 N/GaN (438 nm, blue), In 0.26 Ga 0.74 N/GaN (513 nm, green), and In 0.45 Ga 0.55 N/In 0.13 Ga 0.87 N (602 nm, red) quantum wells (QWs) as an active medium. The QWs corresponding to blue and green light were grown using a conventional growth mode. For the red spectral emission, five-stacked In 0.45 Ga 0.55 N/In 0.13 Ga 0.87 N QWs were realized by the so-called Ga-flow-interruption (Ga-FI) technique, wherein the Ga supply was periodically interrupted during the deposition of In 0.3 Ga 0.7 N to form an In 0.45 Ga 0.55 N well. The vertical and lateral distributions of the three different light emissions were investigated by fluorescence microscope (FM) images. The FM image measured at a focal point in the middle of the n-GaN cladding layer for the red-emitting LED shows that light emissions with flower-like patterns with six petals are periodically observed. The chromaticity coordinates of the electroluminescence spectrum for the white LEDs at an injection current of 80 mA are measured to be (0.316, 0.312), which is close to ideal white light. In contrast with phosphor-free white-light-emitting devices based on nanostructures, our white light device exhibits a mixture of three independent wavelengths by monolithically grown InGaN-based QWs, thus demonstrating a more facile technique to obtain white LEDs.

  5. Engaging Key Stakeholders in Climate Change: A Community-Based Project for Youth-Led Participatory Climate Action

    Science.gov (United States)

    Trott, Carlie D.

    Few studies have examined how youth think about, and take action on climate change and far fewer have sought to facilitate their engagement using participatory methods. This dissertation evaluated the impacts of Science, Camera, Action! (SCA), a novel after-school program that combined climate change education with participatory action through photovoice. The specific aims of this study were to: (1) Evaluate the impacts of SCA on youth participants' climate change knowledge, attitudes, and behaviors; (2) Examine how SCA participation served to empower youth agency; and (3) Explore SCA's influence on youths' science engagement. Participants were 55 youths (ages 10 to 12) across three Boys and Girls Club sites in Northern Colorado. SCA's Science component used interactive activities to demonstrate the interrelationships between Earth's changing climate, ecosystems, and sustainable actions within communities. Photovoice, SCA's Camera component, was used to explore youths' climate change perspectives and to identify opportunities for their active engagement. Finally, SCA's Action component aimed to cultivate youth potential as agents of change in their families and communities through the development and implementation of youth-led action projects. Action projects included local policy advocacy, a tree-planting campaign, a photo gallery opening, development of a website, and the establishment of a Boys and Girls Club community garden. To evaluate SCA impacts, a combination of survey and focus group methods were used. Following the program, youth demonstrated increased knowledge of the scientific and social dimensions of the causes and consequences of climate change, as well as its solutions through human action. Though participants expressed a mix of positive (e.g., hope) and negative (e.g., sadness) emotions about climate change, they left the program with an increased sense of respect for nature, an enhanced sense of environmental responsibility, and a greater sense

  6. Effects of Pharmacist-Led Patient Education on Diabetes-Related Knowledge and Medication Adherence: A Home-Based Study

    Science.gov (United States)

    Chow, Ee Pin; Hassali, Mohamed Azmi; Saleem, Fahad; Aljadhey, Hisham

    2016-01-01

    Objective: Patient education is key to the management of acute and chronic conditions. However, the majority of such educational interventions have been reported from health-care settings. In contrast, this study aims to evaluate whether a home-based intervention can result in better understanding about type 2 diabetes mellitus and can increase…

  7. Utilization of the state led public private partnership program "Chiranjeevi Yojana" to promote facility births in Gujarat, India: a cross sectional community based study.

    Science.gov (United States)

    Yasobant, Sandul; Vora, Kranti Suresh; Shewade, Hemant Deepak; Annerstedt, Kristi Sidney; Isaakidis, Petros; Mavalankar, Dileep V; Dholakia, Nishith B; De Costa, Ayesha

    2016-07-15

    "Chiranjeevi Yojana (CY)", a state-led large-scale demand-side financing scheme (DSF) under public-private partnership to increase institutional delivery, has been implemented across Gujarat state, India since 2005. The scheme aims to provide free institutional childbirth services in accredited private health facilities to women from socially disadvantaged groups (eligible women). These services are paid for by the state to the private facility with the intention of service being free to the user. This community-based study estimates CY uptake among eligible women and explores factors associated with non-utilization of the CY program. This was a community-based cross sectional survey of eligible women who gave birth between January and July 2013 in 142 selected villages of three districts in Gujarat. A structured questionnaire was administered by trained research assistant to collect information on socio-demographic details, pregnancy details, details of childbirth and out-of-pocket (OOP) expenses incurred. A multivariable inferential analysis was done to explore the factors associated with non-utilization of the CY program. Out of 2,143 eligible women, 559 (26 %) gave birth under the CY program. A further 436(20 %) delivered at free public facilities, 713(33 %) at private facilities (OOP payment) and 435(20 %) at home. Eligible women who belonged to either scheduled tribe or poor [aOR = 3.1, 95 % CI:2.4 - 3.8] or having no formal education [aOR = 1.6, 95 % CI:1.1, 2.2] and who delivered by C-section [aOR = 2.1,95 % CI: 1.2, 3.8] had higher odds of not utilizing CY program. Of births at CY accredited facilities (n = 924), non-utilization was 40 % (n = 365) mostly because of lack of required official documentation that proved eligibility (72 % of eligible non-users). Women who utilized the CY program overall paid more than women who delivered in the free public facilities. Uptake of the CY among eligible women was low after almost a decade

  8. Development of III-nitride semiconductors by molecular beam epitaxy and cluster beam epitaxy and fabrication of LEDs based on indium gallium nitride MQWs

    Science.gov (United States)

    Chen, Tai-Chou Papo

    The family of III-Nitrides (the binaries InN, GaN, AIN, and their alloys) is one of the most important classes of semiconductor materials. Of the three, Indium Nitride (InN) and Aluminum Nitride (AIN) have been investigated much less than Gallium Nitride (GaN). However, both of these materials are important for optoelectronic infrared and ultraviolet devices. In particular, since InN was found recently to be a narrow gap semiconductor (Eg=0.7eV), its development should extend the applications of nitride semiconductors to the spectral region appropriate to fiber optics communication and photovoltaic applications. Similarly, the development of AIN should lead to deep UV light emitting diodes (LEDs). The first part of this work addresses the evaluation of structural, optical and transport properties of InN films grown by two different deposition methods. In one method, active nitrogen was produced in the form of nitrogen radicals by a radio frequency (RF) plasma-assisted source. In an alternative method, active nitrogen was produced in the form of clusters containing approximately 2000 nitrogen molecules. These clusters were produced by adiabatic expansion from high stagnation pressure through a narrow nozzle into vacuum. The clusters were singly or doubly ionized with positive charge by electron impact and accelerated up to approximately 20 to 25 KV prior to their disintegration on the substrate. Due to the high local temperature produced during the impact of clusters with the substrate, this method is suitable for the deposition of InN at very low temperatures. The films are auto-doped n-type with carrier concentrations varying from 3 x 1018 to 1020 cm-3 and the electron effective mass of these films was determined to be 0.09m0. The majority of the AIN films was grown by the cluster beam epitaxy method and was doped n- and p- type by incorporating silicon (Si) and magnesium (Mg) during the film deposition. All films were grown under Al-rich conditions at relatively

  9. A randomized controlled trial of a peer co-led dissonance-based eating disorder prevention program for gay men.

    Science.gov (United States)

    Brown, Tiffany A; Keel, Pamela K

    2015-11-01

    Gay males have increased risk for eating disorders compared to heterosexual males, establishing a need to develop and empirically evaluate programs to reduce risk for this population. The present study investigated the acceptability and efficacy of a cognitive dissonance-based (DB) intervention (The PRIDE Body Project(©)) in reducing eating disorder risk factors among gay males in a university-based setting. Eighty-seven gay males were randomized to either a 2-session DB intervention (n = 47) or a waitlist control condition (n = 40). Participants completed eating disorder risk factor assessments pre-intervention, post-intervention, and at 4-week follow-up, and those receiving the intervention completed post-treatment acceptability measures. Acceptability ratings were highly favorable. Regarding efficacy, the DB condition was associated with significantly greater decreases in body dissatisfaction, drive for muscularity, self-objectification, partner-objectification, body-ideal internalization, dietary restraint, and bulimic symptoms compared to waitlist control from pre- to post-intervention. Improvements in the DB group were maintained at 4-week follow-up, with the exception of body-ideal internalization. Body-ideal internalization mediated treatment effects on bulimic symptoms. Results support the acceptability and efficacy of The PRIDE Body Project(©) and provide support for theoretical models of eating pathology in gay men. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Dansk LED - Museumsbelysning

    DEFF Research Database (Denmark)

    Poulsen, Peter Behrensdorff; Dam-Hansen, Carsten; Thorseth, Anders

    Projektet har til formål at anvende dansk forskning inden for optik og lys til at realisere innovative energieffektive LED lyssystemer til museumsbranchen.......Projektet har til formål at anvende dansk forskning inden for optik og lys til at realisere innovative energieffektive LED lyssystemer til museumsbranchen....

  11. Semiconductor lasers and herterojunction leds

    CERN Document Server

    Kressel, Henry

    2012-01-01

    Semiconductor Lasers and Heterojunction LEDs presents an introduction to the subject of semiconductor lasers and heterojunction LEDs. The book reviews relevant basic solid-state and electromagnetic principles; the relevant concepts in solid state physics; and the p-n junctions and heterojunctions. The text also describes stimulated emission and gain; the relevant concepts in electromagnetic field theory; and the modes in laser structures. The relation between electrical and optical properties of laser diodes; epitaxial technology; binary III-V compounds; and diode fabrication are also consider

  12. Extracting light out of LEDs

    Science.gov (United States)

    Muschaweck, Julius; Wiesmann, Christopher

    2013-08-01

    `External quantum efficiency', that is, the number of photons generated per electron passing through the p-n junction of an LED is probably the most important number to quantify the performance of an LED chip. Although advances in epitaxy have increased the fraction of radiative recombination to extremely high values, the extraction of the precious photons that are trapped in a high refractive index crystal is still tricky. In this brief tutorial, we look at the physics of light extraction both from a geometrical optics/thermodynamic and a wave optics point of view, discussing both random and deterministic surface structures.

  13. Design and performance of a three-wavelength LED-based total scatter and backscatter integrating nephelometer

    Directory of Open Access Journals (Sweden)

    T. Müller

    2011-06-01

    Full Text Available Integrating nephelometers are instruments that directly measure a value close to the light scattering coefficient of airborne particles. Different models of nephelometers have been used for decades for monitoring and research applications. Now, a series of nephelometers (Ecotech models M9003, Aurora 1000 and Aurora 3000 with newly designed light sources based on light emitting diodes are available. This article reports on the design of these integrating nephelometers and a comparison of the Aurora 3000 to another commercial instrument (TSI model 3563 that uses an incandescent lamp. Both instruments are three-wavelength, total and backscatter integrating nephelometers.

    We present a characterization of the new light source design of the Aurora 3000 and provide parameterizations for its angular sensitivity functions. These parameterizations facilitate to correct for measurement artefacts using Mie-theory. Furthermore, correction factors are provided as a function of the Ångström exponent. Comparison measurements against the TSI 3563 with laboratory generated white particles and ambient air are also shown and discussed. Both instruments agree well within the calibration uncertainties and detection limit for total scattering with differences less than 5 %. Differences for backscattering are higher by up to 11 %. Highest differences were found for the longest wavelengths, where the signal to noise ratio is lowest. Differences at the blue and green wavelengths are less than 4 % and 3 %, respectively, for both total and backscattering.

  14. Comparison of sequence-based and structure-based phylogenetic ...

    Indian Academy of Sciences (India)

    Prakash

    Sequence-based and structure-based phylogeny. 85. J. Biosci. 32(1), January 2007 dispersion is independent of phylogenetic tree construction algorithms. 3. ... two groups only. 3.1 Families with high correlation between sequence- based and structure-based phylogenetic trees. There are 27 families with considerably high ...

  15. Core-shell GaN-ZnO moth-eye nanostructure arrays grown on a-SiO2/Si (1 1 1) as a basis for improved InGaN-based photovoltaics and LEDs

    Science.gov (United States)

    Rogers, D. J.; Sandana, V. E.; Gautier, S.; Moudakir, T.; Abid, M.; Ougazzaden, A.; Teherani, F. Hosseini; Bove, P.; Molinari, M.; Troyon, M.; Peres, M.; Soares, Manuel J.; Neves, A. J.; Monteiro, T.; McGrouther, D.; Chapman, J. N.; Drouhin, H.-J.; McClintock, R.; Razeghi, M.

    2015-06-01

    Self-forming, vertically-aligned, ZnO moth-eye-like nanoarrays were grown by catalyst-free pulsed laser deposition on a-SiO2/Si (1 1 1) substrates. X-Ray Diffraction (XRD) and Cathodoluminescence (CL) studies indicated that nanostructures were highly c-axis oriented wurtzite ZnO with strong near band edge emission. The nanostructures were used as templates for the growth of non-polar GaN by metal organic vapor phase epitaxy. XRD, scanning electron microscopy, energy dispersive X-ray microanalysis and CL revealed ZnO encapsulated with GaN, without evidence of ZnO back-etching. XRD showed compressive epitaxial strain in the GaN, which is conducive to stabilization of the higher indium contents required for more efficient green light emitting diode (LED) and photovoltaic (PV) operation. Angular-dependent specular reflection measurements showed a relative reflectance of less than 1% over the wavelength range of 400-720 nm at all angles up to 60°. The superior black-body performance of this moth-eye-like structure would boost LED light extraction and PV anti-reflection performance compared with existing planar or nanowire LED and PV morphologies. The enhancement in core conductivity, provided by the ZnO, would also improve current distribution and increase the effective junction area compared with nanowire devices based solely on GaN.

  16. Nurse led, home based self help treatment for patients in primary care with chronic fatigue syndrome: randomised controlled trial.

    Science.gov (United States)

    Wearden, Alison J; Dowrick, Christopher; Chew-Graham, Carolyn; Bentall, Richard P; Morriss, Richard K; Peters, Sarah; Riste, Lisa; Richardson, Gerry; Lovell, Karina; Dunn, Graham

    2010-04-23

    To evaluate the effectiveness of home delivered pragmatic rehabilitation-a programme of gradually increasing activity designed collaboratively by the patient and the therapist-and supportive listening-an approach based on non-directive counselling-for patients in primary care with chronic fatigue syndrome/myalgic encephalomyelitis or encephalitis (CFS/ME). Single blind, randomised, controlled trial. 186 general practices across the north west of England between February 2005 and May 2007. 296 patients aged 18 or over with CFS/ME (median illness duration seven years) diagnosed using the Oxford criteria. Participants were randomly allocated to pragmatic rehabilitation, supportive listening, or general practitioner treatment as usual. Both therapies were delivered at home in 10 sessions over 18 weeks by one of three adult specialty general nurses who had received four months' training, including supervised practice, in each of the interventions. GP treatment as usual was unconstrained except that patients were not to be referred for systematic psychological therapies during the treatment period. Main outcome measures The primary clinical outcomes were fatigue and physical functioning at the end of treatment (20 weeks) and 70 weeks from recruitment compared with GP treatment as usual. Lower fatigue scores and higher physical functioning scores denote better outcomes. A total of 257 (87%) of the 296 patients who entered the trial were assessed at 70 weeks, the primary outcome point. Analysis was on an intention to treat basis, with robust treatment effects estimated after adjustment for missing data using probability weights. Immediately after treatment (at 20 weeks), patients allocated to pragmatic rehabilitation (n=95) had significantly improved fatigue (effect estimate -1.18, 95% confidence interval -2.18 to -0.18; P=0.021) but not physical functioning (-0.18, 95% CI -5.88 to +5.52; P=0.950) compared with patients allocated to treatment as usual (n=100). At one year

  17. LED roadway luminaires evaluation.

    Science.gov (United States)

    2012-02-01

    This research explores whether LED roadway luminaire technologies are a viable future solution to providing roadway lighting. Roadway lighting : enhances highway safety and traffic flow during limited lighting conditions. The purpose of this evaluati...

  18. A school-based peer-led smoking prevention intervention with extracurricular activities: the LILT-LdP cluster randomized controlled trial design and study population.

    Science.gov (United States)

    Bosi, Sandra; Gorini, Giuseppe; Tamelli, Marco; Monti, Claudia; Storani, Simone; Carreras, Giulia; Martini, Andrea; Allara, Elias; Angelini, Paola; Faggiano, Fabrizio

    2013-01-01

    Few school programs are effective in preventing adolescents' tobacco smoking initiation. The "Lega contro i Tumori - Luoghi di Prevenzione" is a cluster randomized controlled trial designed to evaluate a school-based peer-led smoking prevention intervention with extracurricular activities for students aged 14-15 years. This paper presents the study design and the baseline characteristics of the study population. Twenty secondary schools located in the Reggio Emilia province took part in the study. Five schools were excluded because they already participated in smoking prevention interventions. The schools were randomized to control or intervention arms. The study population consisted of students attending the first grade. Components of the intervention included 1) the out-of-school "Smoking Prevention Tour" (SPT) at the "Luoghi di Prevenzione" Center, a 4-hour (4 sessions) extracurricular activity; 2) the "Smoke-free Schools" intervention, combining a life-skills-based peer-led intervention at school, an in-depth lesson on one of the SPT sessions, and enforcement surveillance of the school antismoking policy. Tobacco use was studied through a questionnaire administered before and 6 months after the intervention. Eleven high schools and 9 vocational secondary schools took part in the study for a total of 2,476 out of 3,050 eligible students (81.2%). The proportions of respondents in high schools and vocational secondary schools were 90.9% and 64.5%, respectively (P preventing smoking initiation.

  19. Mixed-method exploratory study of general practitioner and nurse perceptions of a new community based nurse-led heart failure service.

    Science.gov (United States)

    MacKenzie, Emma; Smith, Amanda; Angus, Neil; Menzies, Sue; Brulisauer, Franz; Leslie, Stephen J

    2010-01-01

    The treatment of patients with chronic heart failure (CHF) remains sub-optimal. Specialist CHF nurses are proven to improve care and reduce admission but developing such services, especially in remote areas, can be difficult. This study aimed: first, to assess the perceived acceptability and effectiveness of a new community based nurse-led heart failure service by general practitioners (GPs) in an area with a dispersed population; second, to assess the knowledge and learning needs of GPs; and third, to assess perceptions of the use of national guidelines and telehealth on heart failure management. The study was conducted in the Scottish Highlands, a large geographical area in the north of the UK which includes both rural and urban populations. The area has a total population of 240 000, approximately 60% of whom are within 1 hour travel time of the largest urban centre. A postal survey of all GPs (n = 260) and structured email survey of all CHF specialist nurses (n = 3) was performed. All responses were entered into a Microsoft Excel spreadsheet, summarised and subjected to thematic analysis. Differences between GPs in 'rural', 'urban' or both 'urban & rural' was investigated using an F-test for continuous variables and a three-sample test for equality of proportions for nominal data. Questionnaires were returned from 83 GPs (32%) and all three CHF specialist nurses. In this sample there were only a few differences between GPs from 'rural', 'urban' and 'urban & rural'. There also appeared to be little difference in responses between those who had the experience of the CHF nurse service and those who had not. Overall, 32 GPs (39%) wished better, local access to echocardiography, while 63 (76%) wished access to testing for brain natriuretic peptide (BNP). Only 27 GPs (33%) referred all patients with CHF to hospital. A number of GPs stated that this was dependant on individual circumstances and the patient's ability to travel. The GPs were confident to initiate

  20. LED light recycling using double prisms

    Science.gov (United States)

    Ouyang, George; Li, Kenneth

    2013-09-01

    A novel LED recycling scheme using double prisms is presented. Two identical triangular prisms with square bases, one cross-stacked on top of the other, are tight-fit into a mirrored light tunnel. The whole prism/light tunnel assembly is then mounted on top of a square LED source, whose emitting area is the same as that of the base plane of the said prism/light tunnel assembly. Each prism acts as a tapered-down light guide in one dimension, which selectively retro-reflects high angle light along that direction. The outer light tunnel serves as a mirrored wall that folds back any light that escapes outside the two prisms. For a given collection cone angle, the height of the two prisms is optimized using ASAP, a commercial ray-tracing software. Simulation and experimental results show promise in significantly increasing the brightness of the LED sources within the collection cone. Specifically for a 4x recycling ratio a 70% recycling gain in center illuminance has been achieved (i.e., illuminance measured in the forward direction). This scheme has advantages over previous recycling configurations due to its compactness and ease of mounting. For example, compared to Wavien's spherical reflector approach that has been previously published, the current recycling configuration is much smaller in size because instead of fitting a much larger mirrored reflector on top of the LED source, this time we're using a structure that has the same lateral dimensions as those of the LED source itself. Further improvement is also possible if optimization of various system parameters is carried out.

  1. Reliability-Based Optimization in Structural Engineering

    DEFF Research Database (Denmark)

    Enevoldsen, I.; Sørensen, John Dalsgaard

    1994-01-01

    In this paper reliability-based optimization problems in structural engineering are formulated on the basis of the classical decision theory. Several formulations are presented: Reliability-based optimal design of structural systems with component or systems reliability constraints, reliability-b...

  2. Distribution-Based Cluster Structure Selection.

    Science.gov (United States)

    Yu, Zhiwen; Zhu, Xianjun; Wong, Hau-San; You, Jane; Zhang, Jun; Han, Guoqiang

    2017-11-01

    The objective of cluster structure ensemble is to find a unified cluster structure from multiple cluster structures obtained from different datasets. Unfortunately, not all the cluster structures contribute to the unified cluster structure. This paper investigates the problem of how to select the suitable cluster structures in the ensemble which will be summarized to a more representative cluster structure. Specifically, the cluster structure is first represented by a mixture of Gaussian distributions, the parameters of which are estimated using the expectation-maximization algorithm. Then, several distribution-based distance functions are designed to evaluate the similarity between two cluster structures. Based on the similarity comparison results, we propose a new approach, which is referred to as the distribution-based cluster structure ensemble (DCSE) framework, to find the most representative unified cluster structure. We then design a new technique, the distribution-based cluster structure selection strategy (DCSSS), to select a subset of cluster structures. Finally, we propose using a distribution-based normalized hypergraph cut algorithm to generate the final result. In our experiments, a nonparametric test is adopted to evaluate the difference between DCSE and its competitors. We adopt 20 real-world datasets obtained from the University of California, Irvine and knowledge extraction based on evolutionary learning repositories, and a number of cancer gene expression profiles to evaluate the performance of the proposed methods. The experimental results show that: 1) DCSE works well on the real-world datasets and 2) DCSE based on DCSSS can further improve the performance of the algorithm.

  3. Led-sukellusvalaisin

    OpenAIRE

    Saarelainen, Mikko

    2012-01-01

    Opinnäytetyön aiheena on LED ja sen käyttö sukellusvalaisimissa. Työn tarkoitus oli tutkia miten LED toimii ja miten se soveltuu käytettäväksi sukellusvalaisimessa, sekä syventää omaa tietoutta valosta, mitä se on ja miten sitä mitataan. Työssä käydään läpi LEDin ominaisuuksia ja miten se eroaa muista sukellusvalaisimissa käytetyistä lampuista. Työ on toteutettu tutustumalla LEDiin ja valoon käyttämällä erilaisia lähteitä ja päivittämällä nykyinen sukellusvalaisimeni LED-sukellusvalaisime...

  4. [LED lights in dermatology].

    Science.gov (United States)

    Noé, C; Pelletier-Aouizerate, M; Cartier, H

    2017-04-01

    The use in dermatology of light-emitting diodes (LEDs) continues to be surrounded by controversy. This is due mainly to poor knowledge of the physicochemical phases of a wide range of devices that are difficult to compare to one another, and also to divergences between irrefutable published evidence either at the level of in vitro studies or at the cellular level, and discordant clinical results in a variety of different indications: rejuvenation, acne, wound healing, leg ulcers, and cutaneous inflammatory or autoimmune processes. Therapeutic LEDs can emit wavelengths ranging from the ultraviolet, through visible light, to the near infrared (247-1300 nm), but only certain bands have so far demonstrated any real value. We feel certain that if this article remains factual, then readers will have a different, or at least more nuanced, opinion concerning the use of such LED devices in dermatology. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  5. Are nurse-led chemotherapy clinics really nurse-led? An ethnographic study.

    Science.gov (United States)

    Farrell, Carole; Walshe, Catherine; Molassiotis, Alex

    2017-04-01

    The number of patients requiring ambulatory chemotherapy is increasing year on year, creating problems with capacity in outpatient clinics and chemotherapy units. Although nurse-led chemotherapy clinics have been set up to address this, there is a lack of evaluation of their effectiveness. Despite a rapid expansion in the development of nursing roles and responsibilities in oncology, there is little understanding of the operational aspects of nurses' roles in nurse-led clinics. To explore nurses' roles within nurse-led chemotherapy clinics. A focused ethnographic study of nurses' roles in nurse-led chemotherapy clinics, including semi-structured interviews with nurses. Four chemotherapy units/cancer centres in the UK PARTICIPANTS: Purposive sampling was used to select four cancer centres/units in different geographical areas within the UK operating nurse-led chemotherapy clinics. Participants were 13 nurses working within nurse-led chemotherapy clinics at the chosen locations. Non-participant observation of nurse-led chemotherapy clinics, semi-structured interviews with nurse participants, review of clinic protocols and associated documentation. 61 nurse-patient consultations were observed with 13 nurses; of these 13, interviews were conducted with 11 nurses. Despite similarities in clinical skills training and prescribing, there were great disparities between clinics run by chemotherapy nurses and those run by advanced nurse practitioners. This included the number of patients seen within each clinic, operational aspects, nurses' autonomy, scope of practice and clinical decision-making abilities. The differences highlighted four different levels of nurse-led chemotherapy clinics, based on nurses' autonomy and scope of clinical practice. However, this was heavily influenced by medical consultants. Several nurses perceived they were undertaking holistic assessments, however they were using medical models/consultation styles, indicating medicalization of nurses' roles

  6. Development of gallium-nitride-based light-emitting diodes (LEDs) and laser diodes for energy-efficient lighting and displays

    International Nuclear Information System (INIS)

    DenBaars, Steven P.; Feezell, Daniel; Kelchner, Katheryn; Pimputkar, Siddha; Pan, Chi-Chen; Yen, Chia-Chen; Tanaka, Shinichi; Zhao, Yuji; Pfaff, Nathan; Farrell, Robert; Iza, Mike; Keller, Stacia; Mishra, Umesh; Speck, James S.; Nakamura, Shuji

    2013-01-01

    Light-emitting diodes (LEDs) fabricated from gallium nitride (GaN) have led to the realization of high-efficiency white solid-state lighting. Currently, GaN white LEDs exhibit luminous efficacy greater than 150 lm W −1 , and external quantum efficiencies higher than 60%. This has enabled LEDs to compete with traditional lighting technologies, such as incandescent and compact fluorescent (CFL) lighting. Further improvements in materials quality and cost reduction are necessary for widespread adoption of LEDs for lighting. A review of the unique polarization anisotropy in GaN is included for the different crystal orientations. The emphasis on nonpolar and semipolar LEDs highlights high-power violet and blue emitters, and we consider the effects of indium incorporation and well width. Semipolar GaN materials have enabled the development of high-efficiency LEDs in the blue region and recent achievements of green laser diodes at 520 nm

  7. The clinical effectiveness and cost-effectiveness of home-based, nurse-led health promotion for older people: a systematic review.

    Science.gov (United States)

    Tappenden, P; Campbell, F; Rawdin, A; Wong, R; Kalita, N

    2012-01-01

    In older age, reduction in physical function can lead to loss of independence, the need for hospital and long-term nursing or residential home care, and premature death. Home-visiting programmes for older people, carried out by nurses and other health-care professionals (e.g. occupational therapists and physiotherapists), aim to positively affect health and functional status, and may promote independent functioning of older people. The main research question addressed by this assessment is 'What is the clinical effectiveness and cost-effectiveness of home-based, nurse-led health promotion intervention for older people in the UK?' A comprehensive literature search was undertaken across 12 different databases and research registries from the year 2001 onwards (including MEDLINE, MEDLINE in Process & Other Non-Indexed Citations, EMBASE, Science Citation Index Expanded, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, NHS Health Economic Evaluation Database, Health Technology Assessment Database, Database of Abstracts of Reviews of Effects, Cumulative Index to Nursing and Allied Health Literature). Published systematic reviews were also hand searched to identify other trials previously published. Potentially relevant studies were sifted by one reviewer, and inclusion decisions were agreed among the broader research team. The methodological quality of included studies was assessed using the Cochrane Risk of Bias tool. The results of included studies were synthesised using narrative and statistical methods. A separate systematic search was undertaken to identify existing health economic analyses of home-based, nurse-led health promotion programmes. Included studies were critically appraised using a published checklist. Owing to resource constraints, a de novo health economic model was not developed. Eleven studies were included in the systematic review of clinical effectiveness. There was considerable heterogeneity among the

  8. Recycling of metal-organic chemical vapor deposition waste of GaN based power device and LED industry by acidic leaching: Process optimization and kinetics study

    Science.gov (United States)

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon; Park, Jeung-Jin

    2015-05-01

    Recovery of metal values from GaN, a metal-organic chemical vapor deposition (MOCVD) waste of GaN based power device and LED industry is investigated by acidic leaching. Leaching kinetics of gallium rich MOCVD waste is studied and the process is optimized. The gallium rich waste MOCVD dust is characterized by XRD and ICP-AES analysis followed by aqua regia digestion. Different mineral acids are used to find out the best lixiviant for selective leaching of the gallium and indium. Concentrated HCl is relatively better lixiviant having reasonably faster kinetic and better leaching efficiency. Various leaching process parameters like effect of acidity, pulp density, temperature and concentration of catalyst on the leaching efficiency of gallium and indium are investigated. Reasonably, 4 M HCl, a pulp density of 50 g/L, 100 °C and stirring rate of 400 rpm are the effective optimum condition for quantitative leaching of gallium and indium.

  9. Nurse-led telephone-based follow-up of secondary prevention after acute coronary syndrome: One-year results from the randomized controlled NAILED-ACS trial.

    Directory of Open Access Journals (Sweden)

    Daniel Huber

    Full Text Available Secondary prevention after acute coronary syndrome (ACS could reduce morbidity and mortality, but guideline targets are seldom reached. We hypothesized that nurse-led telephone-based intervention would increase adherence.The NAILED ACS trial is a prospective, controlled, randomized trial. Patients admitted for ACS at Östersund hospital, Sweden, were randomized to usual follow-up by a general practitioner or a nurse-led intervention. The intervention comprised telephone follow-up after 1 month and then yearly with lifestyle counselling and titration of medications until reaching target values for LDL-C (<2.5 mmol/L and blood pressure (BP; <140/90 mmHg or set targets were deemed unachievable. This is a 12-month exploratory analysis of the intervention.A total of 768 patients (396 intervention, 372 control completed the 12-month follow-up. After titration at the 1-month follow-up, mean LDL-C was 0.38 mmol/L (95% CI 0.28 to 0.48, p<0.05, mean systolic BP 7 mmHg (95% CI 4.5 to 9.2, p<0.05, and mean diastolic BP 4 mmHg (95% CI 2.4 to 4.1, p<0.05 lower in the intervention group. Target values for LDL-C and systolic BP were met by 94.1% and 91.9% of intervention patients and 68.4% and 65.6% of controls (p<0.05. At 12 months, mean LDL was 0.3 mmol/L (95% CI 0.1 to 0.4, p <0.05, systolic BP 1.5 mmHg (95% CI -1.0 to 4.1, p = 0.24, and mean diastolic BP 2.1 mmHg (95% CI 0.6 to 3.6, p <0.05 lower in the intervention group. Target values for LDL-C and systolic BP were met in 77.7% and 68.9% of intervention patients and 63.2% and 63.7% of controls (p<0.05 and p = 0.125.Nurse-led telephone-based secondary prevention was significantly more efficient at improving LDL-C and diastolic BP levels than usual care. The effect of the intervention declined between 1 and 12 months. Further evaluation of the persistence to the intervention is needed.

  10. Neurocardiology: Structure-Based Function.

    Science.gov (United States)

    Ardell, Jeffrey L; Armour, John Andrew

    2016-09-15

    Cardiac control is mediated via a series of reflex control networks involving somata in the (i) intrinsic cardiac ganglia (heart), (ii) intrathoracic extracardiac ganglia (stellate, middle cervical), (iii) superior cervical ganglia, (iv) spinal cord, (v) brainstem, and (vi) higher centers. Each of these processing centers contains afferent, efferent, and local circuit neurons, which interact locally and in an interdependent fashion with the other levels to coordinate regional cardiac electrical and mechanical indices on a beat-to-beat basis. This control system is optimized to respond to normal physiological stressors (standing, exercise, and temperature); however, it can be catastrophically disrupted by pathological events such as myocardial ischemia. In fact, it is now recognized that autonomic dysregulation is central to the evolution of heart failure and arrhythmias. Autonomic regulation therapy is an emerging modality in the management of acute and chronic cardiac pathologies. Neuromodulation-based approaches that target select nexus points of this hierarchy for cardiac control offer unique opportunities to positively affect therapeutic outcomes via improved efficacy of cardiovascular reflex control. As such, understanding the anatomical and physiological basis for such control is necessary to implement effectively novel neuromodulation therapies. © 2016 American Physiological Society. Compr Physiol 6:1635-1653, 2016. Copyright © 2016 John Wiley & Sons, Inc.

  11. Investigation on strain relaxation distribution in GaN-based μLEDs by Kelvin probe force microscopy and micro-photoluminescence.

    Science.gov (United States)

    Zhan, Jinglin; Chen, Zhizhong; Jiao, Qianqian; Feng, Yulong; Li, Chengcheng; Chen, Yifan; Chen, Yiyong; Jiao, Fei; Kang, Xiangning; Li, Shunfeng; Wang, Qi; Yu, Tongjun; Zhang, Guoyi; Shen, Bo

    2018-03-05

    GaN/InGaN multi-quantum-wells (MQWs) micron light emitting diodes (µLEDs) with the size ranging from 10 to 300 µm are fabricated. Effects of strain relaxation on the performance of µLEDs have been investigated both experimentally and numerically. Kelvin probe force microscopy (KPFM) and micro-photoluminescence (µPL) are used to characterize the strained area on micron pillars. Strain relaxation and reducing polarization field in MQWs almost affects the whole mesa for 10 µm LEDs and about 4% area around the lateral for 300 µm LEDs. It makes a great contribution to high performance for smaller size µLEDs. Moreover, an indirect nanoscale strain measurement for µLEDs are provided.

  12. Reliability based Design of Coastal Structures

    DEFF Research Database (Denmark)

    Burcharth, H. F.

    2003-01-01

    Conventional design practice for coastal structures is deterministic in nature and is based on the concept of a design load which should not exceed the resistance (carrying capacity) of the structure. The design load is usually defined on a probabilistic basis as a characteristic value of the loa...

  13. The £ for lb. Challenge. Evaluation of a novel, workplace-based peer-led weight management programme, 2014-2016.

    Science.gov (United States)

    Bennett, Damien; Owen, Tracy; Bradley, D T

    2017-09-01

    To evaluate the £ for lb. Challenge, a novel country-wide, workplace-based, peer-led weight management programme with participants from a range of private and public organisations in Northern Ireland. Pre- and post-intervention studies. The intervention was workplace-based, led by volunteer co-worker champions and based on the NHS Choices 12-week weight loss guide which incorporates dietary advice, physical activity, behaviour change methods and weekly weight monitoring. It operated from January to April in three consecutive years (2014-16). Overweight and obese adult workers were eligible. Training of peer champions involved two half-day workshops delivered by dieticians and physical activity professionals. Employers and/or participants pledged £1 to charity for every pound of weight lost. Weight was reported at enrolment and at either 12 weeks (2014) or at 12 weekly intervals (2015-16). Changes in weight and % weight, and body mass index were determined for all the participants and for gender and deprivation subgroups. There were 734, 1559 and 1513 eligible participants, and 21, 31 and 35 participating companies in 2014, 2015 and 2016, respectively. Engagement rates were 94% and 96% and completion rates were 70% and 71% in 2015 and 2016, respectively. Mean weight loss was 1.9 kg (2.2%; 2014), 2.5 kg (2.8%; 2015) and 2.4 kg (2.7%; 2016). The proportions losing ≥5% initial bodyweight were 21% (2014), 24% (2015) and 26% (2016). Male participants were more than twice as likely as women to complete the programme (odds ratio: 2.5 [2015]; 2.2 [2016]) and to lose ≥5% bodyweight (odds ratio: 2.5 [2015]; 3.7 [2016]). The £ for lb. Challenge was an effective, low-cost health improvement intervention with meaningful weight loss for many participants, particularly male workers. With high levels of engagement and ownership, and successful collaboration between public health, voluntary bodies, private companies and public organisations, it is a novel workplace-based

  14. LED lamp incorporating remote phosphor with heat dissipation features

    Science.gov (United States)

    Tong, Tao; Letoquin, Ronan; Keller, Bernd; Tarsa, Eric

    2016-11-22

    An LED lamp or bulb is disclosed that comprises a light source, a heat sink structure and a remote planar phosphor carrier having at least one conversion material. The phosphor carrier can be remote to the light sources and mounted to the heat sink so that heat from the phosphor carrier spreads into the heat sink. The phosphor carrier can comprise a thermally conductive transparent material and a phosphor layer, with an LED based light source mounted to the heat sink such that light from the light source passes through the phosphor carrier. At least some of the LED light is converted by the phosphor carrier, with some lamp embodiments emitting a white light combination of LED and phosphor light. The phosphor arranged according to the present invention can operate at lower temperature to thereby operate at greater phosphor conversion efficiency and with reduced heat related damage to the phosphor.

  15. Luminescent ceramics for LED conversion

    Science.gov (United States)

    Raukas, M.; Wei, G.; Bergenek, K.; Kelso, J.; Zink, N.; Zheng, Y.; Hannah, M.; Stough, M.; Wirth, R.; Linkov, A.; Jermann, F.; Eisert, D.

    2011-03-01

    Many LED-based applications would benefit from more efficient and/or high lumen output devices that enable usage in both white and single color illumination schemes. In the present article we briefly review the materials research history leading to optical ceramic converters and discuss their typical characteristics. Recently demonstrated high performance values in terms of efficacy and external quantum efficiency in orange (amber) spectral region are described.

  16. Plant growth with Led lighting systems

    International Nuclear Information System (INIS)

    Campiotti, C.A.; Bernardini, A.; Di Carlo, F.; Scoccianti, M.; Alonzo, G.; Carlino, M.; Dondi, F.; Bibbiani, C.

    2009-01-01

    Leds lighting is highly relevant for the horticultural industry. Compared to other light sources used for plant production, leds have several properties which are potentially useful in relation to horticulture. However, although LEDs technology has raised strong interest in research for extraterrestrial agriculture, current LEDs panel costs are still too high for commercial adoption in greenhouse sector, and their electrical efficacies do not compete with those of high-pressure sodium lamps, but several manufactures are working to address these issues. When LEDs become practical, their ability to based light sources specifically suitable for photosynthesis and other horticulturally relevant plant properties (i.e. low radiated heat; lighting from within the canopy) will render the narrow band spectrum of LEDs of particular interest for providing light to greenhouse horticulture. A general description of LEDs application and their technical characteristics is briefly reported. [it

  17. Internet-based instructor-led mindfulness for work-related rumination, fatigue, and sleep: Assessing facets of mindfulness as mechanisms of change. A randomized waitlist control trial.

    Science.gov (United States)

    Querstret, Dawn; Cropley, Mark; Fife-Schaw, Chris

    2017-04-01

    This study aimed to extend our theoretical understanding of how mindfulness-based interventions exert their positive influence on measures of occupational health. Employing a randomized waitlist control study design, we sought to (a) assess an Internet-based instructor-led mindfulness intervention for its effect on key factors associated with "recovery from work," specifically, work-related rumination, fatigue, and sleep quality; (b) assess different facets of mindfulness (acting with awareness, describing, nonjudging, and nonreacting) as mechanisms of change; and (c) assess whether the effect of the intervention was maintained over time by following up our participants after 3 and 6 months. Participants who completed the mindfulness intervention (n = 60) reported significantly lower levels of work-related rumination and fatigue, and significantly higher levels of sleep quality, when compared with waitlist control participants (n = 58). Effects of the intervention were maintained at 3- and 6-month follow-up with medium to large effect sizes. The effect of the intervention was primarily explained by increased levels of only 1 facet of mindfulness (acting with awareness). This study provides support for online mindfulness interventions to aid recovery from work and furthers our understanding with regard to how mindfulness interventions exert their positive effects. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  18. In silico structure-based design and synthesis of novel anti-RSV compounds

    NARCIS (Netherlands)

    Cancellieri, Michela; Bassetto, Marcella; Widjaja, Ivy; van Kuppeveld, Frank; de Haan, Cornelis A M; Brancale, Andrea; de Haan, C.A.M.

    2015-01-01

    Respiratory syncytial virus (RSV) is the major cause for respiratory tract disease in infants and young children. Currently, no licensed vaccine or a selective antiviral drug against RSV infections are available. Here, we describe a structure-based drug design approach that led to the synthesis of a

  19. Are community-based nurse-led self-management support interventions effective in chronic patients? Results of a systematic review and meta-analysis.

    Directory of Open Access Journals (Sweden)

    Azzurra Massimi

    Full Text Available The expansion of primary care and community-based service delivery systems is intended to meet emerging needs, reduce the costs of hospital-based ambulatory care and prevent avoidable hospital use by the provision of more appropriate care. Great emphasis has been placed on the role of self-management in the complex process of care of patient with long-term conditions. Several studies have determined that nurses, among the health professionals, are more recommended to promote health and deliver preventive programs within the primary care context. The aim of this systematic review and meta-analysis is to assess the efficacy of the nurse-led self-management support versus usual care evaluating patient outcomes in chronic care community programs. Systematic review was carried out in MEDLINE, CINAHL, Scopus and Web of Science including RCTs of nurse-led self-management support interventions performed to improve observer reported outcomes (OROs and patients reported outcomes (PROs, with any method of communication exchange or education in a community setting on patients >18 years of age with a diagnosis of chronic diseases or multi-morbidity. Of the 7,279 papers initially retrieved, 29 met the inclusion criteria. Meta-analyses on systolic (SBP and diastolic (DBP blood pressure reduction (10 studies-3,881 patients and HbA1c reduction (7 studies-2,669 patients were carried-out. The pooled MD were: SBP -3.04 (95% CI -5.01--1.06, DBP -1.42 (95% CI -1.42--0.49 and HbA1c -0.15 (95% CI -0.32-0.01 in favor of the experimental groups. Meta-analyses of subgroups showed, among others, a statistically significant effect if the interventions were delivered to patients with diabetes (SBP or CVD (DBP, if the nurses were specifically trained, if the studies had a sample size higher than 200 patients and if the allocation concealment was not clearly defined. Effects on other OROs and PROs as well as quality of life remain inconclusive.

  20. Module-based structure design of wheeled mobile robot

    Directory of Open Access Journals (Sweden)

    Z. Luo

    2018-02-01

    Full Text Available This paper proposes an innovative and systematic approach for synthesizing mechanical structures of wheeled mobile robots. The principle and terminologies used for the proposed synthesis method are presented by adopting the concept of modular design, isomorphic and non-isomorphic, and set theory with its associated combinatorial mathematics. The modular-based innovative synthesis and design of wheeled robots were conducted at two levels. Firstly at the module level, by creative design and analysing the structures of classic wheeled robots, a wheel module set containing four types of wheel mechanisms, a suspension module set consisting of five types of suspension frames and a chassis module set composed of five types of rigid or articulated chassis were designed and generalized. Secondly at the synthesis level, two kinds of structure synthesis modes, namely the isomorphic-combination mode and the non-isomorphic combination mode were proposed to synthesize mechanical structures of wheeled robots; which led to 241 structures for wheeled mobile robots including 236 novel ones. Further, mathematical models and a software platform were developed to provide appropriate and intuitive tools for simulating and evaluating performance of the wheeled robots that were proposed in this paper. Eventually, physical prototypes of sample wheeled robots/rovers were developed and tested so as to prove and validate the principle and methodology presented in this paper.

  1. The Development of a Nurse-Led Internet-Based Learning and Self-care Program for Cancer Patients With Symptoms of Anxiety and Depression-A Part of U-CARE.

    Science.gov (United States)

    Hauffman, Anna; Alfonsson, Sven; Mattsson, Susanne; Forslund, Marina; Bill-Axelson, Anna; Nygren, Peter; Johansson, Birgitta

    Having access to information about the disease and being encouraged to participate in self-care activities may reduce anxiety and depression symptoms in cancer patients. Internet-based interventions may be one way to support effective self-care strategies to improve emotional well-being and health-related quality of life. The aim of this study was to describe the development and acceptance of an Internet-based program intended to support cancer patients with anxiety and depression symptoms. A structured collaboration between patients, clinicians, and researchers was used to develop a theory- and evidence-based interactive health communication application (IHCA) based on Orem's self-care deficit nursing theory with influences from Bandura's social learning theory and psychoeducation. The result is an IHCA described as a Nurse-led, Internet-based Learning and Self-care program that helps patients to perform self-care using different types of material in interaction with patients and healthcare staff. The acceptance of the program is consistent with the results of similar studies. Collaboration between patients, clinicians, and researchers seems to be a fruitful approach in the development of an IHCA aiming to support cancer patients' self-care strategies. Well-designed intervention studies are needed to evaluate the effects of the IHCA. This article suggests a theoretical foundation for an IHCA and allows researchers and healthcare providers to take part in the discussion regarding format and content of IHCAs.

  2. Protein structure--based drug design.

    Science.gov (United States)

    Whittle, P J; Blundell, T L

    1994-01-01

    Design cycles will undoubtedly play an increasingly important role in drug discovery in the coming years, as the amount of structural information on protein targets continues to rise. However, the traditional method of drug discovery, based upon random screening and systematic modification of leads by medicinal chemistry techniques, will probably not be abandoned completely because it has a potentially important advantage over more structure-based methods--namely, leads identified in this way are unlikely to show a close resemblance to the natural ligand or substrate. They may, therefore, have advantages in terms of patent novelty, selectivity, or pharmacokinetic profile. However, such leads could then serve as the basis for structure-based, rational modification programs, in which their interactions with target receptors are defined (as we have described) and improved molecules are designed. A final important point to be made about structure-based design in drug discovery is that, while it can be of great use in the initial process of identifying ligands with improved affinity and selectivity in vitro, it can usually say very little about other essential aspects of the drug discovery process, e.g. the need to achieve an adequate pharmacokinetic profile and low toxicity in vivo. This observation reminds us that drug design is a multidisciplinary process, involving molecular biologists, biochemists, pharmacologists, organic chemists, crystallographers, and others. In order to be effective, therefore, structure-based design must be properly integrated into the overall discovery effort.

  3. Deslumbramiento en dispositivos led

    OpenAIRE

    Ixtaina, Rubén Pablo; Presso, Matías; Ferreyra, Joaquín

    2012-01-01

    En el presente trabajo se presenta un estudio realizado en el LAL a dispositivos para señalización (semáforos, balizas, barrales lumínicos) con tecnología led. Las mediciones tradicionales de intensidad luminosa se complementaron con el análisis de la luminancia de los dispositivos, evaluada para diversas aperturas angula-res. Los resultados obtenidos marcan un notorio incre-mento en las luminancias puntuales, para valores de emisión globales comparables a los obtenidos en dispo-sitivos conve...

  4. Improved performance of UV-LED by p-AlGaN with graded composition

    KAUST Repository

    Yan, Jianchang

    2010-11-02

    AlGaN-based ultraviolet light emitting diodes (UV-LEDs) on AlN/sapphire template were grown by metal organic chemical vapour deposition. The AlN template was characterized by atomic force microscopy and high resolution X-ray diffraction. Atomic force microscopy image shows that the AlN surface is very flat, while high resolution X-ray diffraction results prove the good crystalline quality of the AlN template. A novel structure UV-LED which has several p-AlGaN layers with graded composition is compared with a common structure UV-LED which has a single p-Al0.5Ga0.5N layer. The forward bias voltage at 20 mA driving current for the novel structure UV-LED is nearly 3 V higher than that of the common structure UV-LED, however, the electroluminescence intensity of the former is over two times higher than that of the latter. The total quantum efficiency of the novel structure UV-LED is more than 50% higher than that of the common structure UV-LED. The improvement is considered to be the result of better holes injection efficiency in the novel structure UV-LED. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Raising awareness on cyber safety: adolescents' experience of a primary healthcare professional-led, school-based, multi-center intervention.

    Science.gov (United States)

    Tsimtsiou, Zoi; Drosos, Evangelos; Drontsos, Anastasios; Haidich, Anna-Bettina; Dantsi, Fotini; Sekeri, Zafiria; Dardavesis, Theodoros; Nanos, Panagiotis; Arvanitidou, Malamatenia

    2017-09-15

    Purpose Although safe Internet use is an emerging public health issue, there is a scarcity of published work describing relevant school-based interventions. The objective of this study was to explore the impact of a health professional-led, school-based intervention in raising awareness on cyber-safety in adolescents, Therefore, the aim of this study was to investigate adolescents' evaluation of this school-based intervention, 6 months after its implementation, as well as the impact of adolescents' school class and gender on their evaluation. Methods A student sample was selected using a multistage stratified random sampling technique, according to the location and school grade level (middle, high school). The students - aged from 12 to 18 years old experienced an interactive presentation in their classrooms on the amount of time spent online, the use of social networks and the available support services. An evaluation tool was completed anonymously and voluntarily 6 months after the intervention. Results Four hundred and sixty-two students (response rate 90.7%, 246 middle, 216 high school) completed the evaluation tool. Younger students, especially the ones in the first year of middle school, scored significantly higher in all six parameters used in the evaluation of this intervention compared with all the older participants: (a) they had kept the presented information on Safeline and Saferinternet websites and the helpline Ypostirizo (70.2% vs. 33.7%, p impact of the intervention on the youngest students underlines the need for raising awareness on cyber-safety and support services, earlier in the students' life.

  6. Effect of a broad-spectrum LED curing light on the Knoop microhardness of four posterior resin based composites at 2, 4 and 6-mm depths.

    Science.gov (United States)

    ALShaafi, Maan M; Haenel, Thomas; Sullivan, Braden; Labrie, Daniel; Alqahtani, Mohammed Q; Price, Richard B

    2016-02-01

    To measure the Knoop microhardness at the bottom of four posterior resin-based composites (RBCs): Tetric EvoCeram Bulk Fill (Ivoclar Vivadent), SureFil SDR flow (DENTSPLY), SonicFill (Kerr), and x-tra fil (Voco). The RBCs were expressed into metal rings that were 2, 4, or 6-mm thick with a 4-mm internal diameter at 30°C. The uncured specimens were covered by a Mylar strip and a Bluephase 20i (Ivoclar Vivadent) polywave(®) LED light-curing unit was used in high power setting for 20s. The specimens were then removed and placed immediately on a Knoop microhardness-testing device and the microhardness was measured at 9 points across top and bottom surfaces of each specimen. Five specimens were made for each condition. As expected, for each RBC there was no significant difference in the microhardness values at the top of the 2, 4 and 6-mm thick specimens. SureFil SDR Flow was the softest resin, but was the only resin that had no significant difference between the KHN values at the bottom of the 2 and 4-mm (Mixed Model ANOVA pcure was evaluated when determining the depth of cure. SureFil SDR Flow was the softest material and, in accordance with manufacturer's instructions, this RBC should be overlaid with a conventional resin. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Data base on structural materials aging properties

    International Nuclear Information System (INIS)

    Oland, C.B.

    1992-01-01

    The US Nuclear Regulatory Commission has initiated a Structural Aging Program at the Oak Ridge National Laboratory to identify potential structural safety issues related to continued service of nuclear power plants and to establish criteria for evaluating and resolving these issues. One of the tasks in this program focuses on the establishment of a Structural Materials Information Center where long-term and environment-dependent properties of concretes and other structural materials are being collected and assembled into a data base. These properties will be used to evaluate the current condition of critical structural components in nuclear power plants and to estimate the future performance of these materials during the continued service period

  8. IPE data base structure and insights

    International Nuclear Information System (INIS)

    Lehner, J.; Youngblood, R.

    1994-01-01

    A data base (the open-quotes IPE Insights Data Baseclose quotes), has been developed that stores data obtained from the Individual Plant Examinations (IPEs) which licensees of nuclear power plants are conducting in response to the Nuclear Regulatory Commission's (NRC) Generic Letter GL88-20. The data base, which is a collection of linked dBase files, stores information about individual plant designs, core damage frequency, and containment performance in a uniform, structured way. This data base can be queried and used as a computational tool to derive insights regarding the plants for which data is stored. This paper sets out the objectives of the IPE Insights Data Base, describes its structure and contents, illustrates sample queries, and discusses possible future uses

  9. Cost analysis of two community-based HIV testing service modalities led by a Non-Governmental Organization in Cape Town, South Africa.

    Science.gov (United States)

    Meehan, Sue-Ann; Beyers, Nulda; Burger, Ronelle

    2017-12-02

    In South Africa, the financing and sustainability of HIV services is a priority. Community-based HIV testing services (CB-HTS) play a vital role in diagnosis and linkage to HIV care for those least likely to utilise government health services. With insufficient estimates of the costs associated with CB-HTS provided by NGOs in South Africa, this cost analysis explored the cost to implement and provide services at two NGO-led CB-HTS modalities and calculated the costs associated with realizing key HIV outputs for each CB-HTS modality. The study took place in a peri-urban area where CB-HTS were provided from a stand-alone centre and mobile service. Using a service provider (NGO) perspective, all inputs were allocated by HTS modality with shared costs apportioned according to client volume or personnel time. We calculated the total cost of each HTS modality and the cost categories (personnel, capital and recurring goods/services) across each HTS modality. Costs were divided into seven pre-determined project components, used to examine cost drivers. HIV outputs were analysed for each HTS modality and the mean cost for each HIV output was calculated per HTS modality. The annual cost of the stand-alone and mobile modalities was $96,616 and $77,764 respectively, with personnel costs accounting for 54% of the total costs at the stand-alone. For project components, overheads and service provision made up the majority of the costs. The mean cost per person tested at stand-alone ($51) was higher than at the mobile ($25). Linkage to care cost at the stand-alone ($1039) was lower than the mobile ($2102). This study provides insight into the cost of an NGO led CB-HTS project providing HIV testing and linkage to care through two CB-HIV testing modalities. The study highlights; (1) the importance of including all applicable costs (including overheads) to ensure an accurate cost estimate that is representative of the full service implementation cost, (2) the direct link between test

  10. Randomized Trial of a Peer-Led, Telephone-Based Empowerment Intervention for Persons With Chronic Spinal Cord Injury Improves Health Self-Management.

    Science.gov (United States)

    Houlihan, Bethlyn Vergo; Brody, Miriam; Everhart-Skeels, Sarah; Pernigotti, Diana; Burnett, Sam; Zazula, Judi; Green, Christa; Hasiotis, Stathis; Belliveau, Timothy; Seetharama, Subramani; Rosenblum, David; Jette, Alan

    2017-06-01

    To evaluate the impact of "My Care My Call" (MCMC), a peer-led, telephone-based health self-management intervention in adults with chronic spinal cord injury (SCI). Single-blinded randomized controlled trial. General community. Convenience sample of adults with SCI (N=84; mean time post-SCI, 9.9y; mean age, 46y; 73.8% men; 44% with paraplegia; 58% white). Trained peer health coaches applied the person-centered health self-management intervention with 42 experimental subjects over 6 months on a tapered call schedule. The 42 control subjects received usual care. Both groups received the MCMC Resource Guide. Primary outcome-health self-management as measured by the Patient Activation Measure (PAM). Secondary outcomes-global ratings of service/resource use, health-related quality of life, and quality of primary care. Intervention participants averaged 12 calls over 6 months (averaging 21.8min each), with distinct variation. At 6 months, intervention participants reported a significantly greater change in PAM scores (6mo: estimate, 7.029; 95% confidence interval, .1018-13.956; P=.0468) compared with controls, with a trend toward significance at 4 months. At 6 months, intervention participants reported a significantly greater decrease in social/role activity limitations (estimate, -.443; P=.0389), greater life satisfaction (estimate, 1.0091; P=.0522), greater services/resources awareness (estimate, 1.678; P=.0253), greater overall service use (estimate, 1.069; P=.0240), and a greater number of services used (estimate, 1.542; P=.0077). Subgroups most impacted by MCMC on PAM change scores included the following: high social support, white persons, men, 1 to 6 years postinjury, and tetraplegic. This trial demonstrates that the MCMC peer-led, health self-management intervention achieved a positive impact on self-management to prevent secondary conditions in adults with SCI. These results warrant a larger, multisite trial of its efficacy and cost-effectiveness. Copyright

  11. Shoot-and-Trap: Use of specific X-ray damage to study structural protein dynamics by temperature-control led cryo-crystallography

    International Nuclear Information System (INIS)

    Colletier, J.P.; Sanson, B.; Weik, M.; Bourgeois, D.; Fournier, D.; Bourgeois, D.; Silman, I.; Sussman, J.L.

    2008-01-01

    Although X-ray crystallography is the most widely used method for macromolecular structure determination, it does not provide dynamical information, and either experimental tricks or complementary experiments must be used to overcome the inherently static nature of crystallographic structures. Here we used specific X-ray damage during temperature-controlled crystallographic experiments at a third-generation synchrotron source to trigger and monitor (Shoot-and-Trap) structural changes putatively involved in an enzymatic reaction. In particular, a non-hydrolyzable substrate analogue of acetylcholinesterase, the 'off-switch' at cholinergic synapses, was radio-cleaved within the buried enzymatic active site. Subsequent product clearance, observed at 150 K but not at 100 K, indicated exit from the active site possibly via a 'backdoor'. The simple strategy described here is, in principle, applicable to any enzyme whose structure in complex with a substrate analogue is available and, therefore, could serve as a standard procedure in kinetic crystallography studies. (authors)

  12. Comparison of sequence-based and structure-based phylogenetic ...

    Indian Academy of Sciences (India)

    Prakash

    pairs of proteins which are inputs into the construction of phylogenetic trees. We find that correlation between the structure-based dissimilarity measures and the sequence-based dissimilarity measures is usually good if the sequence similarity among the homologues is about 30% or more. For protein families with low ...

  13. Tunable photoluminescence properties and energy transfer in oxyapatite-based Ca2Tb8(SiO4)6:Eu3+ phosphors for UV-LEDs

    International Nuclear Information System (INIS)

    Yang, Che-Yuan; Das, Subrata; Lu, Chung-Hsin

    2015-01-01

    New phosphors Ca 2 Tb 8–x Eu x (SiO 4 ) 6 O 2 with color-tunability were synthesized in this work. The Rietveld refinement indicated that the prepared phosphors were crystallized to a hexagonal structure with space group P6 3 /m (no. 176). When Eu 3+ ions were introduced into Ca 2 Tb 8 (SiO 4 ) 6 O 2 , characteristic red–orange emissions of Eu 3+ ions and the green emission of Tb 3+ ions were obtained. Eu 3+ -doped phosphors emitted with enhanced intensity and had broader excitation spectra than the undoped Ca 2 Tb 8 (SiO 4 ) 6 O 2 phosphors. As Eu 3+ content increased, a decline in Tb 3+ emission was observed owing to resonant energy transfer from the 5 D 3 level of Tb 3+ ions to the 5 D 0 level of Eu 3+ ions. Moreover, the transfer of energy from Tb 3+ ions to Eu 3+ ions proceeded via a dipole–dipole interaction, and the critical distance for this energy transfer was calculated to be 7.2 Å. The efficiency of energy transfer in Ca 2 Tb 8−x Eu x (SiO 4 ) 6 O 2 increased from 72% to 87% with an increase in the Eu 3+ concentration, x, from 0.02 to 0.08. The emitted color of Ca 2 Tb 8−x Eu x (SiO 4 ) 6 O 2 was tuned from green to red via controlling the concentration of Eu 3+ ions. Meanwhile, the optimum phosphor system Ca 2 Tb 7.94 Eu 0.6 (SiO 4 ) 6 O 2 exhibited adequate thermal stability even at 200 °C and the corresponding activation energy was calculated to be 0.027 eV. These results suggest that Ca 2 Tb 8 (SiO 4 ) 6 O 2 :Eu 3+ may be potential phosphors for the application in UV LEDs. - Highlights: • New phosphors Ca 2 Tb 8−x Eu x (SiO 4 ) 6 O 2 were synthesized in this work. • The structure of Ca 2 Tb 8−x Eu x (SiO 4 ) 6 O 2 was refined to be P6 3 /m (no. 176). • As Eu 3+ was doped into the host, efficient energy transfer from Tb 3+ to Eu 3+ was observed. • The efficiency of energy transfer increased with the concentration of Eu 3+ . • The emitted color of the present phosphors was tuned from green to red.

  14. Coordinate-based versus structural approaches to brain image analysis.

    Science.gov (United States)

    Mangin, J-F; Rivière, D; Coulon, O; Poupon, C; Cachia, A; Cointepas, Y; Poline, J-B; Le Bihan, D; Régis, J; Papadopoulos-Orfanos, D

    2004-02-01

    A basic issue in neurosciences is to look for possible relationships between brain architecture and cognitive models. The lack of architectural information in magnetic resonance images, however, has led the neuroimaging community to develop brain mapping strategies based on various coordinate systems without accurate architectural content. Therefore, the relationships between architectural and functional brain organizations are difficult to study when analyzing neuroimaging experiments. This paper advocates that the design of new brain image analysis methods inspired by the structural strategies often used in computer vision may provide better ways to address these relationships. The key point underlying this new framework is the conversion of the raw images into structural representations before analysis. These representations are made up of data-driven elementary features like activated clusters, cortical folds or fiber bundles. Two classes of methods are introduced. Inference of structural models via matching across a set of individuals is described first. This inference problem is illustrated by the group analysis of functional statistical parametric maps (SPMs). Then, the matching of new individual data with a priori known structural models is described, using the recognition of the cortical sulci as a prototypical example.

  15. GaN-based flip-chip LEDs with highly reflective ITO/DBR p-type and via hole-based n-type contacts for enhanced current spreading and light extraction

    Science.gov (United States)

    Zhou, Shengjun; Zheng, Chenju; Lv, Jiajiang; Gao, Yilin; Wang, Ruiqing; Liu, Sheng

    2017-07-01

    We demonstrate GaN-based double-layer electrode flip-chip light-emitting diodes (DLE-FCLED) with highly reflective indium-tin oxide (ITO)/distributed bragg reflector (DBR) p-type contact and via hole-based n-type contacts. Transparent thin ITO in combination with TiO2/SiO2 DBR is used for reflective p-type ohmic contact, resulting in a significant reduction in absorption of light by opaque metal electrodes. The finely distributed via hole-based n-type contacts are formed on the n-GaN layer by etching via holes through p-GaN and multiple quantum well (MQW) active layer, leading to reduced lateral current spreading length, and hence alleviated current crowding effect. The forward voltage of the DLE-FCLED is 0.31 V lower than that of the top-emitting LED at 90 mA. The light output power of DLE-FCLED is 15.7% and 80.8% higher than that of top-emitting LED at 90 mA and 300 mA, respectively. Compared to top- emitting LED, the external quantum efficiency (EQE) of DLE-FCLED is enhanced by 15.4% and 132% at 90 mA and 300 mA, respectively. The maximum light output power of the DLE-FCLED obtained at 195.6 A/cm2 is 1.33 times larger than that of the top-emitting LED obtained at 93 A/cm2.

  16. Vibrational Based Inspection of Civil Engineering Structures

    DEFF Research Database (Denmark)

    Rytter, Anders

    and Structural Engineering at the University of Aalborg since the beginning of 1992. Both projects have been supported by the Danish Technical Research Council. Further, the first mentioned project was supported by the Danish Energy Agency. Their financial support is gratefully acknowledged.......The thesis has been written in relation to two different research projects. Firstly, an offshore test programme, Integrated Experimental/Numerical Analysis of the Dynamic behavior of offshore structures, which was performed at the department of Building Technology and Structural Engineering...... at the University of Aalborg from 1988 to 1991. Secondly, a research project, In-Field Vibration Based Inspection of Civil Engineering Structures, which has been performed as a pilot project by the Consulting Engineers Rambøll, Hannemann and Højlund in cooperation with the department of Building Technology...

  17. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    2015-05-29

    May 29, 2015 ... Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the ...

  18. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    Abstract. Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the dominant ...

  19. On the switching speed of SOI LEDs

    NARCIS (Netherlands)

    Schmitz, Jurriaan; de Vries, R.; Salm, Cora; Hoang, T.; Hueting, Raymond Josephus Engelbart; Holleman, J.

    2008-01-01

    Recently, we presented a novel design for a silicon LED in SmartCUT™ SOI wafers. It exhibits a record quantum efficiency for SOI-based silicon LEDs and opens the way to the integration of light emitters in a VLSI process on SOI. In this paper, we present first experimental and modeling results

  20. Influence of variation of electrical parameters values of RGB LEDs on the radiation uniformity of LED displays at minimal luminosity grade

    Directory of Open Access Journals (Sweden)

    Veleschuk V. P.

    2017-06-01

    Full Text Available The emission uniformity of LED chips in the entire range of brightness and colors is the problem in LED displays manufacture process. It was approved that at lowering brightness gradations appearing the radiation nonuniformity between LED chips, and the higher disorders will be seen on the lesser emission levels. The RGB LED chips, observed by us, were based on AlGaInP (red, In0.3Ga0.7N/GaN (green, and In0,2Ga0,8NN/ GaN (blue and had nominal working current 20 mA. Analysis of the current-voltage characteristics and capacitance-voltage characteristics showed the presence of inhomogeneous semiconductor junctions and ohmic contacts in blue LEDs structures that are the source of possible irregularities in the final emission of LED displays. The variation of voltages (at current 10 mA were 2.81—2.98 V for blue structures, and 1.9—2.0 V for red ones. Some of the blue structures had additional parasite current-flow mechanism at low current. Rise time and fall time of electroluminescence pulse of blue structures were measured. The shortest LED pulse time in LED displays is limited by duration of 6—8 ns. The quality of LED displays may be improved by implementating the preliminary control of LED chips in a narrower range of voltage variation at operating currents, or more narrow interval of I—V variation. This additional LEDs sorting will of course reduce the percentage of the total amount of light-emitting diodes, but may improve the image (video, photo quality at translations by using a lower brightness gradations.

  1. FREQUENCY CHARACTERISTICS OF MODERN LED PHOSPHOR MATERIALS

    Directory of Open Access Journals (Sweden)

    Maxim S. Fudin

    2014-11-01

    Full Text Available Frequency characteristics of modern LED phosphor materials have been considered for the purpose of assessing the prospects of phosphor-based LEDs in wireless communication data systems which use optical wavelengths. The measurements have been carried out on the dependence of the emission intensity of single LEDs and LED chip-on-board modules with phosphors based on yttrium-aluminum and lutetium-aluminum garnets (with or without addition of nitridebased phosphors as well as silicate-based phosphors, on the frequency of electric pulses exciting the emission. It was shown that from the point of view of data transmission rate, garnet-based phosphors (including systems with added nitride phosphors are more promising than silicate–based ones. Garnet-based materials can be used in optical communication data systems with bandwidth (without extra modulation applied up to 3 MHz with single–chip LEDs and up to 4.5 MHz with 9- chip LED chip-on-board modules. The results of the work indicate that a significant part of white LEDs used in general lighting systems can be even now used for data transfer, for example, in systems assisting positioning in closed spaces to facilitate people searching necessary rooms or objects

  2. NMR in structure-based drug design.

    Science.gov (United States)

    Carneiro, Marta G; Ab, Eiso; Theisgen, Stephan; Siegal, Gregg

    2017-11-08

    NMR spectroscopy is a powerful technique that can provide valuable structural information for drug discovery endeavors. Here, we discuss the strengths (and limitations) of NMR applications to structure-based drug discovery, highlighting the different levels of resolution and throughput obtainable. Additionally, the emerging field of paramagnetic NMR in drug discovery and recent developments in approaches to speed up and automate protein-observed NMR data collection and analysis are discussed. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  3. Structure Based Predictive Model for Coal Char Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Robert Hurt; Joseph Calo; Robert Essenhigh; Christopher Hadad

    2000-12-30

    This unique collaborative project has taken a very fundamental look at the origin of structure, and combustion reactivity of coal chars. It was a combined experimental and theoretical effort involving three universities and collaborators from universities outside the U.S. and from U.S. National Laboratories and contract research companies. The project goal was to improve our understanding of char structure and behavior by examining the fundamental chemistry of its polyaromatic building blocks. The project team investigated the elementary oxidative attack on polyaromatic systems, and coupled with a study of the assembly processes that convert these polyaromatic clusters to mature carbon materials (or chars). We believe that the work done in this project has defined a powerful new science-based approach to the understanding of char behavior. The work on aromatic oxidation pathways made extensive use of computational chemistry, and was led by Professor Christopher Hadad in the Department of Chemistry at Ohio State University. Laboratory experiments on char structure, properties, and combustion reactivity were carried out at both OSU and Brown, led by Principle Investigators Joseph Calo, Robert Essenhigh, and Robert Hurt. Modeling activities were divided into two parts: first unique models of crystal structure development were formulated by the team at Brown (PI'S Hurt and Calo) with input from Boston University and significant collaboration with Dr. Alan Kerstein at Sandia and with Dr. Zhong-Ying chen at SAIC. Secondly, new combustion models were developed and tested, led by Professor Essenhigh at OSU, Dieter Foertsch (a collaborator at the University of Stuttgart), and Professor Hurt at Brown. One product of this work is the CBK8 model of carbon burnout, which has already found practical use in CFD codes and in other numerical models of pulverized fuel combustion processes, such as EPRI's NOxLOI Predictor. The remainder of the report consists of detailed

  4. Deployable structures for a human lunar base

    Science.gov (United States)

    Gruber, Petra; Häuplik, Sandra; Imhof, Barbara; Özdemir, Kürsad; Waclavicek, Rene; Perino, Maria Antoinetta

    2007-06-01

    The study Lunar exploration architecture—deployable structures for a lunar base was performed within the Alcatel Alenia Space “Lunar Exploration Architecture” study for the European Space Agency. The purpose of the study was to investigate bionic concepts applicable to deployable structures and to interpret the findings for possible implementation concepts. The study aimed at finding innovative solutions for deployment possibilities. Translating folding/unfolding principles from nature, candidate geometries were developed and researched using models, drawings and visualisations. The use of materials, joints between structural elements and construction details were investigated for these conceptual approaches. Reference scenarios were used to identify the technical and environmental conditions, which served as design drivers. Mechanical issues and the investigation of deployment processes narrowed the selection down to six chosen concepts. Their applicability was evaluated at a conceptual stage in relation to the timescale of the mission.

  5. Reliability Based Optimization of Structural Systems

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    1987-01-01

    The optimization problem to design structural systems such that the reliability is satisfactory during the whole lifetime of the structure is considered in this paper. Some of the quantities modelling the loads and the strength of the structure are modelled as random variables. The reliability...... is estimated using first. order reliability methods ( FORM ). The design problem is formulated as the optimization problem to minimize a given cost function such that the reliability of the single elements satisfies given requirements or such that the systems reliability satisfies a given requirement....... For these optimization problems it is described how a sensitivity analysis can be performed. Next, new optimization procedures to solve the optimization problems are presented. Two of these procedures solve the system reliability based optimization problem sequentially using quasi-analytical derivatives. Finally...

  6. GaN-Based Thin Film Vertical Structure Light Emitting Diodes Fabricated by a Modified Laser Lift-off Process and Transferred to Cu

    International Nuclear Information System (INIS)

    Sun Yong-Jian; Yu Tong-Jun; Jia Chuan-Yu; Chen Zhi-Zhong; Tian Peng-Fei; Kang Xiang-Ning; Lian Gui-Jun; Huang Sen; Zhang Guo-Yi

    2010-01-01

    GaN-based thin film vertical structure light-emitting diodes (VS-LEDs) were fabricated by a modified YAG laser lift-off (LLO) process and transferred to Cu substrates. With a comparison of the electrical and optical properties of conventional LEDs on sapphire substrates and of lateral structure thin film LEDs by a KrF LLO process, the vertical structure of LLO LEDs shows obvious superiority. LLO VSLEDs made by modified YAG LLO process show less increase of leakage current than the devices made by conventional KrF LLO process. Furthermore, owing to the well current spreading and less current path, the ideality factors and series resistance of vertical structure LEDs reduce greatly and the efficiency increases more obviously than the lateral structure LEDs, which is also reflected on the relative L-I curves. The output power of vertical structure LEDs is over 3 times greater than that of the lateral structure LLO LEDs within 300mA. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Transient voltage suppressor diode designed for the protection of high-brightness GaN-based LEDs from various electrostatic discharge shocks

    International Nuclear Information System (INIS)

    Bouangeune, Daoheung; Lee, Yeji; Cho, Jaehee; Shim, Kyuhwan; Choi, Cheljong; Choi, Sangsik; Cho, Deokho

    2014-01-01

    Transient voltage suppressor (TVS) diodes were fabricated using low-temperature epitaxy technology and were employed to improve the electrostatic discharge (ESD) strength of GaN light emitting diodes (LEDs). The ESD performance and the protection capability of the TVS diodes were investigated using various ESD simulators of the human body model (HBM), the IEC (International Electrotechnical Commission) 61000-4-2 (IEC), and a transmission line pulse (TLP) analysis. According to the IEC, the manufactured TVS diode could withstand in excess of ±30 kV without any degradation in the I-V characteristics; meanwhile, the GaN LED itself exhibited catastrophic degradation caused by weak ESD power. The GaN LED assembled with the TVS diode had improved ESD robustness from ±3.8 kV to ±8 kV according to the HBM, from ±1.2 kV to > ±30 kV according to the IEC, and from 4.3 A to > ±30 A according to the TLP analysis. Furthermore, its performance was maintained perfect I-V manner with negligible changes in radiant power, leakage current and breakdown voltage up to the limit of the ESD simulators. Namely, the manufactured TVS diodes were effective in the protection of sensitive GaN LEDs from very strong ESD shocks.

  8. A Hybrid Integrated Laboratory and Inquiry-Based Research Experience: Replacing Traditional Laboratory Instruction with a Sustainable Student-Led Research Project

    Science.gov (United States)

    Hartings, Matthew R.; Fox, Douglas M.; Miller, Abigail E.; Muratore, Kathryn E.

    2015-01-01

    The Department of Chemistry at American University has replaced its junior- and senior-level laboratory curriculum with two, two-semester long, student-led research projects as part of the department's American Chemical Society-accredited program. In the first semester of each sequence, a faculty instructor leads the students through a set of…

  9. Base isolation strategies for structures and components

    International Nuclear Information System (INIS)

    Varma, Veto; Reddy, G.R.; Vaze, K.K.; Kushwaha, H.S.

    2003-08-01

    In the present report the effect of laminated rubber bearing (LRB) system on the dynamic response of the structure was studied. A LRB system was designed and tested in the laboratory for its dynamic characteristics. Finite element analysis was also performed and based on this analysis, isolator for PHWR nuclear power plant was designed. Analysis of the building was performed with and without isolator. Comparison of responses was made in terms of frequencies, accelerations and displacements and floor response spectra. (author)

  10. Advances in LEDs for automotive applications

    Science.gov (United States)

    Bhardwaj, Jy; Peddada, Rao; Spinger, Benno

    2016-03-01

    High power LEDs were introduced in automotive headlights in 2006-2007, for example as full LED headlights in the Audi R8 or low beam in Lexus. Since then, LED headlighting has become established in premium and volume automotive segments and beginning to enable new compact form factors such as distributed low beam and new functions such as adaptive driving beam. New generations of highly versatile high power LEDs are emerging to meet these application needs. In this paper, we will detail ongoing advances in LED technology that enable revolutionary styling, performance and adaptive control in automotive headlights. As the standards which govern the necessary lumens on the road are well established, increasing luminance enables not only more design freedom but also headlight cost reduction with space and weight saving through more compact optics. Adaptive headlighting is based on LED pixelation and requires high contrast, high luminance, smaller LEDs with high-packing density for pixelated Matrix Lighting sources. Matrix applications require an extremely tight tolerance on not only the X, Y placement accuracy, but also on the Z height of the LEDs given the precision optics used to image the LEDs onto the road. A new generation of chip scale packaged (CSP) LEDs based on Wafer Level Packaging (WLP) have been developed to meet these needs, offering a form factor less than 20% increase over the LED emitter surface footprint. These miniature LEDs are surface mount devices compatible with automated tools for L2 board direct attach (without the need for an interposer or L1 substrate), meeting the high position accuracy as well as the optical and thermal performance. To illustrate the versatility of the CSP LEDs, we will show the results of, firstly, a reflector-based distributed low beam using multiple individual cavities each with only 20mm height and secondly 3x4 to 3x28 Matrix arrays for adaptive full beam. Also a few key trends in rear lighting and impact on LED light

  11. Structural analysis of a phosphide-based epitaxial structure with a buried oxidized AlAs sacrificial layer

    Science.gov (United States)

    Englhard, M.; Reuters, B.; Baur, J.; Klemp, C.; Zaumseil, P.; Schroeder, T.; Skibitzki, O.

    2017-06-01

    Phosphide-based thin-film light-emitting diodes (TF-LEDs) lattice-matched to GaAs are well established in optoelectronics in the wavelength range between 550 and 650 nm. In this work, we investigate the impact of oxidized AlAs to overlying phosphide-based pseudomorphically grown epitaxial structures. Oxidation of a buried AlAs sacrificial layer allows the separation of the grown TF-LED epitaxy from its substrates and enables an oxidation lift-off process. To evaluate the strain effect of progressing oxidation on the structure of the chip, we perform high-resolution x-ray diffraction analysis on as-grown, mesa-structured, semi-oxidized, and completely laterally oxidized chips. At each state, a pseudomorphic phosphide-based InAlP layer is found. The InAlP layer exhibits a tensile out-of-plane strain of approximately 0.20% and a compressive in-plane strain of approx. -0.19%. Additionally, scanning transmission electron microscopy, energy-dispersive x-ray spectroscopy, and μ-photoluminescence were used for investigation of the boundary zone of the oxidation front of AlAs, the interfaces between phosphide-based semiconductors (InAlP/InGaAlP) and oxidized amorphous AlAs and the light emission of InGaAlP multiple quantum wells.

  12. White LEDs with limit luminous efficacy

    Science.gov (United States)

    Lisitsyn, V. M.; Lukash, V. S.; Stepanov, S. A.; Yangyang, Ju

    2016-01-01

    In most promising widespread gallium nitride based LEDs emission is generated in the blue spectral region with a maximum at about 450 nm which is converted to visible light with the desired spectrum by means of phosphor. The thermal energy in the conversion is determined by the difference in the energies of excitation and emission quanta and the phosphor quantum yield. Heat losses manifest themselves as decrease in the luminous efficacy. LED heating significantly reduces its efficiency and life. In addition, while heating, the emission generation output and the efficiency of the emission conversion decrease. Therefore, the reduction of the energy losses caused by heating is crucial for LED development. In this paper, heat losses in phosphor-converted LEDs (hereinafter chips) during spectrum conversion are estimated. The limit values of the luminous efficacy for white LEDs are evaluated.

  13. White LEDs with limit luminous efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Lisitsyn, V. M.; Stepanov, S. A., E-mail: stepanovsa@tpu.ru; Yangyang, Ju [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Lukash, V. S. [JSC Research Institute of Semiconductor Devices, 99a Krasnoarmeyskaja St., Tomsk, 634050 (Russian Federation)

    2016-01-15

    In most promising widespread gallium nitride based LEDs emission is generated in the blue spectral region with a maximum at about 450 nm which is converted to visible light with the desired spectrum by means of phosphor. The thermal energy in the conversion is determined by the difference in the energies of excitation and emission quanta and the phosphor quantum yield. Heat losses manifest themselves as decrease in the luminous efficacy. LED heating significantly reduces its efficiency and life. In addition, while heating, the emission generation output and the efficiency of the emission conversion decrease. Therefore, the reduction of the energy losses caused by heating is crucial for LED development. In this paper, heat losses in phosphor-converted LEDs (hereinafter chips) during spectrum conversion are estimated. The limit values of the luminous efficacy for white LEDs are evaluated.

  14. Harmonics Monitoring Survey on LED Lamps

    Directory of Open Access Journals (Sweden)

    Abdelrahman Ahmed Akila

    2017-03-01

    Full Text Available Light Emitting Diode (LED lamps are being increasingly used in many applications. These LED lamps operate using a driver, which is a switching device. Hence, LED lamps will be a source of harmonics in the power system. These harmonics if not well treated, may cause severe performance and operational problems. In this paper, harmonics (amplitude and phase angles generated by both LED lamps and conventional fluorescent lamps will be studied practically. Then they will be analyzed and evaluated. Compared to each other harmonics generated by both LED and conventional florescent lamps, self mitigation may occur based on the phase angle of these harmonics. All data will be measured using power analyzer and will be done on a sample of actual lamps.

  15. Protein structure based prediction of catalytic residues

    Science.gov (United States)

    2013-01-01

    Background Worldwide structural genomics projects continue to release new protein structures at an unprecedented pace, so far nearly 6000, but only about 60% of these proteins have any sort of functional annotation. Results We explored a range of features that can be used for the prediction of functional residues given a known three-dimensional structure. These features include various centrality measures of nodes in graphs of interacting residues: closeness, betweenness and page-rank centrality. We also analyzed the distance of functional amino acids to the general center of mass (GCM) of the structure, relative solvent accessibility (RSA), and the use of relative entropy as a measure of sequence conservation. From the selected features, neural networks were trained to identify catalytic residues. We found that using distance to the GCM together with amino acid type provide a good discriminant function, when combined independently with sequence conservation. Using an independent test set of 29 annotated protein structures, the method returned 411 of the initial 9262 residues as the most likely to be involved in function. The output 411 residues contain 70 of the annotated 111 catalytic residues. This represents an approximately 14-fold enrichment of catalytic residues on the entire input set (corresponding to a sensitivity of 63% and a precision of 17%), a performance competitive with that of other state-of-the-art methods. Conclusions We found that several of the graph based measures utilize the same underlying feature of protein structures, which can be simply and more effectively captured with the distance to GCM definition. This also has the added the advantage of simplicity and easy implementation. Meanwhile sequence conservation remains by far the most influential feature in identifying functional residues. We also found that due the rapid changes in size and composition of sequence databases, conservation calculations must be recalibrated for specific

  16. Reagentless, Structure-Switching, Electrochemical Aptamer-Based Sensors.

    Science.gov (United States)

    Schoukroun-Barnes, Lauren R; Macazo, Florika C; Gutierrez, Brenda; Lottermoser, Justine; Liu, Juan; White, Ryan J

    2016-06-12

    The development of structure-switching, electrochemical, aptamer-based sensors over the past ∼10 years has led to a variety of reagentless sensors capable of analytical detection in a range of sample matrices. The crux of this methodology is the coupling of target-induced conformation changes of a redox-labeled aptamer with electrochemical detection of the resulting altered charge transfer rate between the redox molecule and electrode surface. Using aptamer recognition expands the highly sensitive detection ability of electrochemistry to a range of previously inaccessible analytes. In this review, we focus on the methods of sensor fabrication and how sensor signaling is affected by fabrication parameters. We then discuss recent studies addressing the fundamentals of sensor signaling as well as quantitative characterization of the analytical performance of electrochemical aptamer-based sensors. Although the limits of detection of reported electrochemical aptamer-based sensors do not often reach that of gold-standard methods such as enzyme-linked immunosorbent assays, the operational convenience of the sensor platform enables exciting analytical applications that we address. Using illustrative examples, we highlight recent advances in the field that impact important areas of analytical chemistry. Finally, we discuss the challenges and prospects for this class of sensors.

  17. Structure-based inhibitors of tau aggregation

    Science.gov (United States)

    Seidler, P. M.; Boyer, D. R.; Rodriguez, J. A.; Sawaya, M. R.; Cascio, D.; Murray, K.; Gonen, T.; Eisenberg, D. S.

    2018-02-01

    Aggregated tau protein is associated with over 20 neurological disorders, which include Alzheimer's disease. Previous work has shown that tau's sequence segments VQIINK and VQIVYK drive its aggregation, but inhibitors based on the structure of the VQIVYK segment only partially inhibit full-length tau aggregation and are ineffective at inhibiting seeding by full-length fibrils. Here we show that the VQIINK segment is the more powerful driver of tau aggregation. Two structures of this segment determined by the cryo-electron microscopy method micro-electron diffraction explain its dominant influence on tau aggregation. Of practical significance, the structures lead to the design of inhibitors that not only inhibit tau aggregation but also inhibit the ability of exogenous full-length tau fibrils to seed intracellular tau in HEK293 biosensor cells into amyloid. We also raise the possibility that the two VQIINK structures represent amyloid polymorphs of tau that may account for a subset of prion-like strains of tau.

  18. Designing with LED

    OpenAIRE

    Johnson, Amanda

    2018-01-01

    This presentation focuses on the recently adopted changes in the way highway lighting systems are designed, with emphasis on how the approved list of solid state–based luminaires is integrated into the design process. Progress made on the approved list and experiences in developing it will also be shared.

  19. Physician-led team triage based on lean principles may be superior for efficiency and quality? A comparison of three emergency departments with different triage models

    Directory of Open Access Journals (Sweden)

    Burström Lena

    2012-08-01

    Full Text Available Abstract Background The management of emergency departments (EDs principally involves maintaining effective patient flow and care. Different triage models are used today to achieve these two goals. The aim of this study was to compare the performance of different triage models used in three Swedish EDs. Using efficiency and quality indicators, we compared the following triage models: physician-led team triage, nurse first/emergency physician second, and nurse first/junior physician second. Methods All data of patients arriving at the three EDs between 08:00- and 21:00 throughout 2008 were collected and merged into a database. The following efficiency indicators were measured: length of stay (LOS including time to physician, time from physician to discharge, and 4-hour turnover rate. The following quality indicators were measured: rate of patients left before treatment was completed, unscheduled return within 24 and 72 hours, and mortality rate within 7 and 30 days. Results Data from 147,579 patients were analysed. The median length of stay was 158 minutes for physician-led team triage, compared with 243 and 197 minutes for nurse/emergency physician and nurse/junior physician triage, respectively (p  Conclusions Physician-led team triage seemed advantageous, both expressed as efficiency and quality indicators, compared with the two other models.

  20. Integrated aerobic biological-chemical treatment of winery wastewater diluted with urban wastewater. LED-based photocatalysis in the presence of monoperoxysulfate.

    Science.gov (United States)

    Solís, Rafael R; Rivas, Francisco Javier; Ferreira, Leonor C; Pirra, Antonio; Peres, José A

    2018-01-28

    The oxidation of Winery Wastewater (WW) by conventional aerobic biological treatment usually leads to inefficient results due to the presence of organic substances, which are recalcitrant or toxic in conventional procedures. This study explores the combination of biological and chemical processes in order to complete the oxidation of biodegradable and non-biodegradable compounds in two sequential steps. Thus, a biological oxidation of a diluted WW is carried out by using the activated sludge process. Activated sludge was gradually acclimated to the Diluted Winery Wastewater (DWW). Some aspects concerning the biological process were evaluated (kinetics of the oxidation and sedimentation of the sludge produced). The biological treatment of the DWW led to a 40-50% of Chemical Oxygen Demand (COD) removal in 8 h, being necessary the application of an additional process. Different chemical processes combining UVA-LEDs radiation, monoperoxysulfate (MPS) and photocatalysts were applied in order to complete the COD depletion and efficient removal of polyphenols content, poorly oxidized in the previous biological step. From the options tested, the combination of UVA, MPS and a novel LaCoO 3 -TiO 2 composite, with double route of MPS decomposition through heterogeneous catalysis and photocatalysis, led to the best results (95% of polyphenol degradation, and additional 60% of COD removal). Initial MPS concentration and pH effect in this process were assessed.

  1. Heterostructures for Increased Quantum Efficiency in Nitride LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Robert F. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2010-09-30

    Task 1. Development of an advanced LED simulator useful for the design of efficient nitride-based devices. Simulator will contain graphical interface software that can be used to specify the device structure, the material parameters, the operating conditions and the desired output results. Task 2. Theoretical and experimental investigations regarding the influence on the microstructure, defect concentration, mechanical stress and strain and IQE of controlled changes in the chemistry and process route of deposition of the buffer layer underlying the active region of nitride-based blue- and greenemitting LEDs. Task 3. Theoretical and experimental investigations regarding the influence on the physical properties including polarization and IQE of controlled changes in the geometry, chemistry, defect density, and microstructure of components in the active region of nitride-based blue- and green-emitting LEDs. Task 4. Theoretical and experimental investigations regarding the influence on IQE of novel heterostructure designs to funnel carriers into the active region for enhanced recombination efficiency and elimination of diffusion beyond this region. Task 5. Theoretical and experimental investigations regarding the influence of enhanced p-type doping on the chemical, electrical, and microstructural characteristics of the acceptor-doped layers, the hole injection levels at Ohmic contacts, the specific contact resistivity and the IQE of nitride-based blue- and green-emitting LEDs. Development and optical and electrical characterization of reflective Ohmic contacts to n- and p-type GaN films.

  2. Optimization of structure parameters for highly efficient AlGaN based deep ultraviolet light emitting diodes

    Science.gov (United States)

    Mondal, Ramit Kumar; Chatterjee, Vijay; Singh, Sumitra; Islam, Sk Masiul; Pal, Suchandan

    2017-12-01

    The efficiency of any LEDs critically depends on its base structure. In this paper, we have reported the dependence of active layer structure on the performance of AlGaN based deep ultraviolet light emitting diodes (LEDs) having emission wavelength at 265 nm which is very crucial for DNA manipulation of most of the water borne harmful pathogens. Advanced device simulations have been performed for the deep UV-LEDs by using SiLENSE module of the SimuLED software tool. We have optimized the number of quantum well, quantum well thickness, aluminum content in electron blocking layer (EBL) and the aluminum content in the barrier region. We have observed that optimization of structural properties plays a crucial role in improving the internal quantum efficiency leading to improvement of overall efficiency of the LEDs. The internal quantum efficiency of the UVsbnd LED having an emission wavelength of 265 nm reaches up to 55% when the number of quantum well is fixed to five and each well has a thickness in the order of 1.8 nm with aluminum content as 95% and 62% in EBL and barrier region respectively.

  3. An informal school-based, peer-led intervention for prevention of tobacco consumption in adolescence: A cluster randomized trial in rural Gandhinagar

    Directory of Open Access Journals (Sweden)

    Anjali Sunil Kumar Mall

    2017-01-01

    Full Text Available Background: Tobacco use among adolescence is one of the important preventable causes of death as well as a leading public health problem all over the world. The present study was conducted with the objective of studying the effect of peer-led interventions on tobacco use among adolescents. Materials and Methods: Twenty schools were randomly selected and ten schools each were identified as cluster for intervention and control groups. A total of 402 students in intervention group and 422 in control group were studied. Results: About 48% and 41% of adolescents were consuming smokeless tobacco in any form in the intervention and control groups, respectively. Prevalence of consumption of smokeless tobacco was significantly high among boys as compared to girls. Pan masala was the most common form of consumption. After conducting A Stop Smoking in School Trial-like peer-led intervention, a significant reduction in tobacco consumption of any form was observed in the intervention group (48%–36% during the follow-up (Z = 3.2, P < 0.01. A significant reduction in exposure to passive smoking in the intervention group (32%–29% was also observed. All the students smoking initially had stopped smoking at the end of the follow-up in both the groups. Conclusion: It was found that peer-led intervention was effective in reducing the consumption of smokeless tobacco in any form. The rate of reduction was more in the first follow-up as compared to the end of the intervention. Sustained intervention in the form of retraining is needed for the long-term effect.

  4. Tungsten - Yttrium Based Nuclear Structural Materials

    Science.gov (United States)

    Ramana, Chintalapalle; Chessa, Jack; Martinenz, Gustavo

    2013-04-01

    The challenging problem currently facing the nuclear science community in this 21st century is design and development of novel structural materials, which will have an impact on the next-generation nuclear reactors. The materials available at present include reduced activation ferritic/martensitic steels, dispersion strengthened reduced activation ferritic steels, and vanadium- or tungsten-based alloys. These materials exhibit one or more specific problems, which are either intrinsic or caused by reactors. This work is focussed towards tungsten-yttrium (W-Y) based alloys and oxide ceramics, which can be utilized in nuclear applications. The goal is to derive a fundamental scientific understanding of W-Y-based materials. In collaboration with University of Califonia -- Davis, the project is designated to demonstrate the W-Y based alloys, ceramics and composites with enhanced physical, mechanical, thermo-chemical properties and higher radiation resistance. Efforts are focussed on understanding the microstructure, manipulating materials behavior under charged-particle and neutron irradiation, and create a knowledge database of defects, elemental diffusion/segregation, and defect trapping along grain boundaries and interfaces. Preliminary results will be discussed.

  5. Results of Investigations on the Blink Reflex as a Protective Means against Laser and LED Radiation: A Description Based on Fundamental Psychophysical Laws

    International Nuclear Information System (INIS)

    Hans-Dieter Reidenbach

    2006-01-01

    2,650 volunteers have been investigated in blink-reflex studies with various test equipment, where a laser beam or a single element L.E.D. or an array have been used to irradiate the human eye in order to initiate a physiological reaction. In addition 1,196 volunteers took part in aversion response studies. 491 persons out of 2,650, i.e., 18.53 %, showed a blink reflex or lid closure, upon exposure to irradiation from a laser or an L.E.D.. Only 6.19 %, i. e., 74 out of 1,196 volunteers, showed other aversion responses, like gross eye or head movements. The different parameters which are mainly responsible for the respective results concerning the blink reflex will be dealt with and explained, as they have been achieved up to now. In addition some experimentally verified dependencies on fundamental psychophysical laws will be described. Besides the statement that the blink reflex should not be used as a sufficient physiological protective means it can be generally stated that in order to ensure their safety, in spite of the missing blink-reflex and other aversion responses, users of low-power lasers should be instructed to perform active protective reactions, e.g., to close the eyes voluntarily and simultaneously move the head away from the beam in the case of an unintentional exposure or intrabeam viewing. (author)

  6. LED driver for stroboscopic interferometry

    Science.gov (United States)

    Paulin, T.; Heikkinen, V.; Kassamakov, I.; Hæggström, E.

    2012-04-01

    Three different types of white light emitting diodes (LEDs) and three types of single color LEDs were tested as light sources for stroboscopic scanning white light interferometry (SSWLI) for dynamic (MEMS) characterization. Short, intense, light pulses and low duty cycle (DC-10 MHz), and can drive single LEDs at 5A peak current (0.7% duty cycle at 1 MHz). The shortest measured electrical pulses were 6.2 +/- 0.1 ns FDHM. The minimum measured Full Duration at Half Maximum (FDHM) of the optical pulse was 8.4 +/- 0.1 ns using nonphosphor white LED and 32.1 +/- 0.1 ns using white phosphor-converted LED (0.7 % duty cycle at 1 MHz in both cases). The minimum optical pulse FDHM for a single color blue/green LED was 6.4 +/- 0.1 ns. The maximum intensity of these pulses was 630 +/- 40 μW and 540 +/- 30 μW, respectively. All types of white LEDs could be used for stroboscopic SWLI measurements at frequencies up to 2 MHz. For higher frequencies, non-phosphor white LEDs must be used together with a cyan LED to avoid ringing in the SWLI interferogram.

  7. Nobel Prize for blue LEDs

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2015-01-01

    A brief review of lighting technologies is presented. Unavoidable restrictions for incandescent light bulbs caused by the Planck distribution and properties of the human eye are illustrated. The efficiency and luminous efficacy of thermal radiation are calculated for various temperatures; the results clearly show the limitations for thermal radiators. The only way to overcome these limitations is using non-thermal radiators, such as fluorescent lamps and light-emitting diodes (LEDs). Unique advantages of LEDs undoubtedly made a revolution in this field. A crucial element of this progress is the blue LEDs (Nobel Prize 2014). Some experiments with a blue and a green LED are described: (i) the luminescence triggered in a green-yellow phosphor inside a white LED by the blue LED; (ii) radiant spectra and ‘efficiency droop’ in the LEDs; (iii) modulation of the blue LED up to 4 MHz; and (iv) the h/e ratio from the turn-on voltage of the green LED. The experiments are suitable for undergraduate laboratories and usable as classroom demonstrations. (paper)

  8. Nobel Prize for blue LEDs

    Science.gov (United States)

    Kraftmakher, Yaakov

    2015-05-01

    A brief review of lighting technologies is presented. Unavoidable restrictions for incandescent light bulbs caused by the Planck distribution and properties of the human eye are illustrated. The efficiency and luminous efficacy of thermal radiation are calculated for various temperatures; the results clearly show the limitations for thermal radiators. The only way to overcome these limitations is using non-thermal radiators, such as fluorescent lamps and light-emitting diodes (LEDs). Unique advantages of LEDs undoubtedly made a revolution in this field. A crucial element of this progress is the blue LEDs (Nobel Prize 2014). Some experiments with a blue and a green LED are described: (i) the luminescence triggered in a green-yellow phosphor inside a white LED by the blue LED; (ii) radiant spectra and ‘efficiency droop’ in the LEDs; (iii) modulation of the blue LED up to 4 MHz; and (iv) the h/e ratio from the turn-on voltage of the green LED. The experiments are suitable for undergraduate laboratories and usable as classroom demonstrations.

  9. Physician-led team triage based on lean principles may be superior for efficiency and quality? A comparison of three emergency departments with different triage models

    Science.gov (United States)

    2012-01-01

    Background The management of emergency departments (EDs) principally involves maintaining effective patient flow and care. Different triage models are used today to achieve these two goals. The aim of this study was to compare the performance of different triage models used in three Swedish EDs. Using efficiency and quality indicators, we compared the following triage models: physician-led team triage, nurse first/emergency physician second, and nurse first/junior physician second. Methods All data of patients arriving at the three EDs between 08:00- and 21:00 throughout 2008 were collected and merged into a database. The following efficiency indicators were measured: length of stay (LOS) including time to physician, time from physician to discharge, and 4-hour turnover rate. The following quality indicators were measured: rate of patients left before treatment was completed, unscheduled return within 24 and 72 hours, and mortality rate within 7 and 30 days. Results Data from 147,579 patients were analysed. The median length of stay was 158 minutes for physician-led team triage, compared with 243 and 197 minutes for nurse/emergency physician and nurse/junior physician triage, respectively (p triage, 5.3% for nurse/emergency physician, and 9.6% for nurse/junior physician triage (p triage, 1.0%, compared with 2.1%, and 2.5% for nurse/emergency physician, and nurse/junior physician, respectively (p triage and 1.0% for the two other triage models (p triage seemed advantageous, both expressed as efficiency and quality indicators, compared with the two other models. PMID:22905993

  10. 'No blue' LED solution for photolithography room illumination

    DEFF Research Database (Denmark)

    Ou, Haiyan; Corell, Dennis Dan; Dam-Hansen, Carsten

    2010-01-01

    This paper explored the feasibility of using a LED-based bulb as the illumination light source for photolithography room. A no-blue LED was designed, and the prototype was fabricated. The spectral power distribution of both the LED bulb and the yellow fluorescent tube was measured. Based on that,...

  11. Vision based condition assessment of structures

    International Nuclear Information System (INIS)

    Uhl, Tadeusz; Kohut, Piotr; Holak, Krzysztof; Krupinski, Krzysztof

    2011-01-01

    In this paper, a vision-based method for measuring a civil engineering construction's in-plane deflection curves is presented. The displacement field of the analyzed object which results from loads was computed by means of a digital image correlation coefficient. Image registration techniques were introduced to increase the flexibility of the method. The application of homography mapping enabled the deflection field to be computed from two images of the structure, acquired from two different points in space. An automatic shape filter and a corner detector were implemented to calculate the homography mapping between the two views. The developed methodology, created architecture and the capabilities of software tools, as well as experimental results obtained from tests made on a lab set-up and civil engineering constructions, are discussed.

  12. Vision based condition assessment of structures

    Energy Technology Data Exchange (ETDEWEB)

    Uhl, Tadeusz; Kohut, Piotr; Holak, Krzysztof; Krupinski, Krzysztof, E-mail: tuhl@agh.edu.pl, E-mail: pko@agh.edu.pl, E-mail: holak@agh.edu.pl, E-mail: krzysiek.krupinski@wp.pl [Department of Robotics and Mechatronics, AGH-University of Science and Technology, Al.Mickiewicza 30, 30-059 Cracow (Poland)

    2011-07-19

    In this paper, a vision-based method for measuring a civil engineering construction's in-plane deflection curves is presented. The displacement field of the analyzed object which results from loads was computed by means of a digital image correlation coefficient. Image registration techniques were introduced to increase the flexibility of the method. The application of homography mapping enabled the deflection field to be computed from two images of the structure, acquired from two different points in space. An automatic shape filter and a corner detector were implemented to calculate the homography mapping between the two views. The developed methodology, created architecture and the capabilities of software tools, as well as experimental results obtained from tests made on a lab set-up and civil engineering constructions, are discussed.

  13. Structure Based Antibody-Like Peptidomimetics

    Directory of Open Access Journals (Sweden)

    Mark I. Greene

    2012-02-01

    Full Text Available Biologics such as monoclonal antibodies (mAb and soluble receptors represent new classes of therapeutic agents for treatment of several diseases. High affinity and high specificity biologics can be utilized for variety of clinical purposes. Monoclonal antibodies have been used as diagnostic agents when coupled with radionuclide, immune modulatory agents or in the treatment of cancers. Among other limitations of using large molecules for therapy the actual cost of biologics has become an issue. There is an effort among chemists and biologists to reduce the size of biologics which includes monoclonal antibodies and receptors without a reduction of biological efficacy. Single chain antibody, camel antibodies, Fv fragments are examples of this type of deconstructive process. Small high-affinity peptides have been identified using phage screening. Our laboratory used a structure-based approach to develop small-size peptidomimetics from the three-dimensional structure of proteins with immunoglobulin folds as exemplified by CD4 and antibodies. Peptides derived either from the receptor or their cognate ligand mimics the functions of the parental macromolecule. These constrained peptides not only provide a platform for developing small molecule drugs, but also provide insight into the atomic features of protein-protein interactions. A general overview of the reduction of monoclonal antibodies to small exocyclic peptide and its prospects as a useful diagnostic and as a drug in the treatment of cancer are discussed.

  14. Green perovskite light emitting diodes based on the ITO/Al2O3/CsPbBr3 heterojunction structure

    Science.gov (United States)

    Zhuang, Shiwei; Ma, Xue; Hu, Daqiang; Dong, Xin; Zhang, Yuantao; Zhang, Baolin

    2018-03-01

    Perovskite light emitting diodes (PeLEDs) now emerge as a promising new optoelectronic application field for these amazing semiconductors. For the purpose of investigating the device structures and light emission mechanisms of PeLEDs, we have fabricated green PeLEDs based on the ITO/Al2O3/CsPbBr3 heterojunction structure. The emission layer inorganic perovskite CsPbBr3 film with small grain sizes (∼28.9 nm) was prepared using a two-step method. The device exhibits a typical rectification behavior with turn-on voltage of ∼6 V. The EL emission band is narrow with the FWHM of ∼25 nm. The peak EQE of the device was ∼0.09%. The working mechanism of the device is also discussed. The result of the present work provides a feasible innovation idea of PeLEDs fabrication and great potentials for the development of perovskite based LEDs.

  15. New dental applications with LEDs

    DEFF Research Database (Denmark)

    Argyraki, A.; Ou, Yiyu; Petersen, Paul Michael

    Visible and ultraviolet LEDs will in the future give rise to new dental applications. Fluorescence imaging, photodynamic therapy and photoactivated disinfection are important future candidates for diagnostics and treatment in dentistry.......Visible and ultraviolet LEDs will in the future give rise to new dental applications. Fluorescence imaging, photodynamic therapy and photoactivated disinfection are important future candidates for diagnostics and treatment in dentistry....

  16. Structure-Based Algorithms for Microvessel Classification

    KAUST Repository

    Smith, Amy F.

    2015-02-01

    © 2014 The Authors. Microcirculation published by John Wiley & Sons Ltd. Objective: Recent developments in high-resolution imaging techniques have enabled digital reconstruction of three-dimensional sections of microvascular networks down to the capillary scale. To better interpret these large data sets, our goal is to distinguish branching trees of arterioles and venules from capillaries. Methods: Two novel algorithms are presented for classifying vessels in microvascular anatomical data sets without requiring flow information. The algorithms are compared with a classification based on observed flow directions (considered the gold standard), and with an existing resistance-based method that relies only on structural data. Results: The first algorithm, developed for networks with one arteriolar and one venular tree, performs well in identifying arterioles and venules and is robust to parameter changes, but incorrectly labels a significant number of capillaries as arterioles or venules. The second algorithm, developed for networks with multiple inlets and outlets, correctly identifies more arterioles and venules, but is more sensitive to parameter changes. Conclusions: The algorithms presented here can be used to classify microvessels in large microvascular data sets lacking flow information. This provides a basis for analyzing the distinct geometrical properties and modelling the functional behavior of arterioles, capillaries, and venules.

  17. Large Optoelectronic Enhancement of Light-Harvesting Polymers by Chain Confinement and Charge Percolation for LEDs and Photocells Based on Ultrathin Films and CNT Nanocomposites

    Science.gov (United States)

    2010-09-30

    different substrates. This substrate effect diminished when the film t hickness became thicker than ~80 nm. Moreover, films of same thicknesses but...Xie J, Chandrasekhar A, Abraham J, Varadan VK. Smart Materials and Structures 2004;13: 295-8. [13] Karim MR, Lee CJ, Lee MS. Journal of Polymer...Xie, J. N.; Chandrasekhar, A.; Abraham , J.; Varadan, V. K. Smart Materials & Structures 2004, 13, 295. 14. Stauffer, D.; Aharony, A. Introduction to

  18. Cost-effectiveness of a nurse-led telemonitoring intervention based on peak expiratory flow measurements in asthmatics: results of a randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Wouters Emiel FM

    2007-07-01

    Full Text Available Abstract Background Asthma is a chronic lung disease in which recurrent asthma symptoms create a substantial burden to individuals and their families. At the same time the economic burden associated with asthma is considerable. Methods The cost-effectiveness study was part of a single centre prospective randomised controlled trial comparing a nurse-led telemonitoring programme to usual care in a population of asthmatic outpatients. The study included 109 asthmatic outpatients (56 children; 53 adults. The duration of follow-up was 12 months, and measurements were performed at baseline, 4, 8, and 12 months. Patients were asked to transfer their monitor data at least twice daily and by judging the received data and following a stepwise intervention protocol a nurse was able to act as the main caregiver in the intervention group. In both groups the EQ-5D and the SF-6D were used to obtain estimates of health state utilities. One year health care costs, patient and family costs, and productivity losses were calculated. The mean incremental costs were weighted against the mean incremental effect in terms of QALY. Results The study population generally represented mild to moderate asthmatics. No significant differences were found between the groups with regard to the generic quality of life. Overall, the mean health care costs per patient were higher in the intervention group than in the control group. The intervention costs mainly caused the cost difference between the groups. The intervention costs the society € 31,035/QALY gained with regard to adults and with regard to children € 59,071/QALY gained. Conclusion If the outcome is measured by generic quality of life the nurse-led telemonitoring programme is of limited cost-effectiveness in the study population. From the societal perspective the probability of the programme being cost-effective compared to regular care was 85% at a ceiling ratio of € 80,000/QALY gained among the adults and 68

  19. Design of an elliptic spot illumination system in LED-based color filter-liquid-crystal-on-silicon pico projectors for mobile embedded projection.

    Science.gov (United States)

    Chen, Enguo; Yu, Feihong

    2012-06-01

    We present an elliptic spot illumination system for a color filter-liquid-crystal-on-silicon (CF-LCoS) pico projector employing a specifically designed free-form lens and a cylindrical lens to improve on previous designs in terms of optical efficiency while yielding an ultracompact and low-cost optical architecture. The detailed design description of the optical system is thoroughly investigated. Simulation results coincide well with the theoretical calculation. The single 1  mm×1  mm LED chip-powered optical engine, which employs a CF-LCoS panel with a diagonal of 0.28 in and an aspect ratio of 4:3, has an estimated output efficiency over 9.8% (11.8 lm@1 W) and an ANSI 9-point uniformity over 88.5%, with the ultrasmall volume 24  mm×19  mm×7  mm. Compared to the circular spot-illuminated projection system, a total increment of about 23% of system efficiency is available with this improved optical engine. It is believed that there would be a huge market potential to commercialize our design.

  20. An Efficient Nurse Practitioner-Led Community-Based Service Model for Delivering Coordinated Care to Persons With Serious Mental Illness at Risk for Homelessness [Formula: see text].

    Science.gov (United States)

    Baker, Jeannemarie; Travers, Jasmine L; Buschman, Penelope; Merrill, Jacqueline A

    Access to mental health care is a struggle for those with serious mental illness (SMI). About 25% of homeless suffer from SMI, compared with 4.2% of the general population. From 2003 to 2012, St. Paul's Center (SPC) operated a unique model to provide quality care to the homeless and those at risk for homelessness, incarceration, and unnecessary hospitalization because of SMI. Data were available for analysis for the years 2008 to 2010. The SPC was developed, managed, and staffed by board-certified psychiatric/mental health nurse practitioners, offering comprehensive mental health services and coordinated interventions. All clients were housed and none incarcerated. From 2008 to 2010, only 3% of clients were hospitalized, compared with 7.5% of adults with SMI. Clinical, academic, and community partnerships increased value, but Medicaid reimbursement was not available. Mental health provisions in the recently passed 21st Century Cures Act support community mental health specialty treatment. The SPC provides a template for similar nurse practitioner-led models.

  1. A Simplified, Light Emitting Diode (LED Based, Modular System to be Used for the Rapid Evaluation of Fruit and Vegetable Quality: Development and Validation on Dye Solutions

    Directory of Open Access Journals (Sweden)

    Raffaele Civelli

    2015-09-01

    Full Text Available NIR spectroscopy has proven to be one of the most efficient and ready to transfer tools to monitor product’s quality. Portable VIS/NIR instruments are particularly versatile and suitable for field use to monitor the ripening process or quality parameters. The aim of this work is to develop and evaluate a new simplified optoelectronic system for potential measurements on fruit and vegetables directly in the field. The development, characterization and validation of an operative prototype is discussed. LED technology was chosen for the design, and spectral acquisition at four specific wavelengths (630, 690, 750 and 850 nm was proposed. Nevertheless, attention was given to the modularity and versatility of the system. Indeed, the possibility to change the light sources module with other wavelengths allows one to adapt the use of the same device for different foreseeable applications and objectives, e.g., ripeness evaluation, detection of particular diseases and disorders, chemical and physical property prediction, shelf life analysis, as well as for different natures of products (berry, leaf or liquid. Validation tests on blue dye water solutions have shown the capability of the system of discriminating low levels of reflectance, with a repeatability characterized by a standard deviation proportional to the measured intensity and in general limited to 2%–4%.

  2. SDSL-ESR-based protein structure characterization

    NARCIS (Netherlands)

    Strancar, J.; Kavalenka, A.A.; Urbancic, I.; Ljubetic, A.; Hemminga, M.A.

    2010-01-01

    As proteins are key molecules in living cells, knowledge about their structure can provide important insights and applications in science, biotechnology, and medicine. However, many protein structures are still a big challenge for existing high-resolution structure-determination methods, as can be

  3. Reliability-Based Optimization of Structural Elements

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    In this paper structural elements from an optimization point of view are considered, i.e. only the geometry of a structural element is optimized. Reliability modelling of the structural element is discussed both from an element point of view and from a system point of view. The optimization...

  4. Video-based versus Medical Personnel-led Training for the Knowledge on Condom Use, Partner Notification and Sexually Transmitted Infections in Rural Communities in Thailand: A Randomized Comparison Pilot Study

    Directory of Open Access Journals (Sweden)

    Nut Kittipongphat

    2017-09-01

    Full Text Available Objective: To compare the knowledge regarding partner notification (PN, condom use (CU and sexually transmitted infections (STIs after video-based or medical personnel-led training. Methods: From December 2016 to January 2017, we conducted an opened-label randomized study in four communities (20 participants/ community in Bangsaphannoi district, Prachuabkirikhan province. In each community, the participants were randomly allocated into Group A (medical personnel-led training or Group B (video-based training. Both trainings covered similar contents which included knowledge about STIs (5 minutes; how to safely notify their partners (10 minutes and techniques of correct condom use (10 minutes. Participants’ knowledge was assessed by five one-best questions for each topic before and after the training. Comparison of scores within group and between groups was done by using Wilcoxon rank sum test and Wilcoxon signed rank test. P <0.05 was considered statistically significant. Results: From 160 eligible participants, 148 could complete the study (74 in Group A and 74 in Group B. Between two groups, there was no difference of participants’ characteristics, including age, education, employment, sex debut, STIs and number of partners. Both training techniques significantly improved participants’ knowledge and there was no difference between them. The lowest median score and least improvement of knowledge were found in PN. Conclusion: At the community level, both video-based training and medical personnel-led training improve the knowledge on PN, CU and STIs with comparable results.

  5. Home blood pressure monitoring with nurse-led telephone support among patients with hypertension and a history of stroke: a community-based randomized controlled trial.

    Science.gov (United States)

    Kerry, Sally M; Markus, Hugh S; Khong, Teck K; Cloud, Geoffrey C; Tulloch, Jenny; Coster, Denise; Ibison, Judith; Oakeshott, Pippa

    2013-01-08

    Adequate control of blood pressure reduces the risk of recurrent stroke. We conducted a randomized controlled study to determine whether home blood pressure monitoring with nurse-led telephone support would reduce blood pressure in patients with hypertension and a history of stroke. We recruited 381 participants (mean age 72 years) from outpatient and inpatient stroke clinics between Mar. 1, 2007, and Aug. 31, 2009. Nearly half (45%, 170) of the participants had some disability due to stroke. Participants were visited at home for a baseline assessment and randomly allocated to home blood pressure monitoring (n = 187) or usual care (n = 194). Those in the intervention group were given a monitor, brief training and telephone support. Participants who had home blood pressure readings consistently over target (target < 130/80 mm Hg) were advised to consult their family physician. The main outcome measure was a fall in systolic blood pressure after 12 months, measured by an independent researcher unaware of group allocation. Despite more patients in the intervention group than in the control group having changes to antihypertensive treatment during the trial period (60.1% [98/163] v. 47.6% [78/164], p = 0.02), the fall in systolic blood pressure from baseline did not differ significantly between the groups (adjusted mean difference 0.3 mm Hg, 95% confidence interval -3.6 to 4.2 mm Hg). Subgroup analysis showed significant interaction with disability due to stroke (p = 0.03 at 6 months) and baseline blood pressure (p = 0.03 at 12 months). Overall, home monitoring did not improve blood pressure control in patients with hypertension and a history of stroke. It was associated with a fall in systolic pressure in patients who had uncontrolled blood pressure at baseline and those without disability due to stroke. ClinicalTrials.gov registration NCT00514800.

  6. Light pipes for LED measurements

    Science.gov (United States)

    Floyd, S. R.; Thomas, E. F., Jr.

    1976-01-01

    Light pipe directly couples LED optical output to single detector. Small area detector measures total optical output of diode. Technique eliminates thermal measurement problems and channels optical output to remote detector.

  7. Practical lighting design with LEDs

    CERN Document Server

    Lenk, Ron

    2016-01-01

    The second edition of Practical Lighting Design with LEDs has been revised and updated to provide the most current information for developing light-emitting diodes products. The authors, noted authorities in the field, offer a review of the most relevant topics including optical performance, materials, thermal design, and modeling and measurement. Comprehensive in scope, the text covers all the information needed to design LEDs into end products.

  8. Structure based alignment and clustering of proteins (STRALCP)

    Science.gov (United States)

    Zemla, Adam T.; Zhou, Carol E.; Smith, Jason R.; Lam, Marisa W.

    2013-06-18

    Disclosed are computational methods of clustering a set of protein structures based on local and pair-wise global similarity values. Pair-wise local and global similarity values are generated based on pair-wise structural alignments for each protein in the set of protein structures. Initially, the protein structures are clustered based on pair-wise local similarity values. The protein structures are then clustered based on pair-wise global similarity values. For each given cluster both a representative structure and spans of conserved residues are identified. The representative protein structure is used to assign newly-solved protein structures to a group. The spans are used to characterize conservation and assign a "structural footprint" to the cluster.

  9. Effectiveness of composite resin polymerization using light-emitting diodes (LEDs or halogen-based light-curing units Efetividade de polimerização de uma resina composta fotopolimerizada por diodos emissores de luz (LEDs ou luz halógena

    Directory of Open Access Journals (Sweden)

    Bianca Micali

    2004-09-01

    Full Text Available The clinical performance of composite resins is greatly influenced by the quality of the light-curing unit used. The aim of this study was to compare the efficiency of a commercial light-emitting diode (LED with that of a halogen-based light-curing unit by means of dye penetration of a micro hybrid composite resin. The composite resin evaluated was Filtek Z250 (3M Dental. The composite was filled into acrylic moulds that were randomly polymerized for 40 seconds by each of the light-emitting systems: light-emitting diode Ultraled (Dabi Atlante or halogen light Degulux (Degussa Hüls curing units. Immediately after polymerization, each specimen was individually immersed in 1 ml of 2% methylene blue solution at 37°C ± 2°C. After 24 hours, the specimens were rinsed under running distilled water for 1 minute and stored at 37°C ± 2°C at relative humidity for 24 hours. The composite resins were removed from the moulds and individually triturated before being immersed in new test tubes containing 1 ml of absolute alcohol for 24 hours. The solutions were filtered and centrifuged for 3 minutes at 4,000 rpm and the supernatant was used to determine absorbance in a spectrophotometer at 590 nm. To verify the differences between groups polymerized by LED or halogen light t-test was applied. No significant differences were found between composite resins light-cured by LED or halogen light-curing unit (p > 0.05. The commercially LED-based light-curing unit is as effective to polymerize hybrid composite resins as the halogen-based unit.A longevidade clínica das resinas compostas é grandemente influenciada pela qualidade do aparelho fotopolimerizador utilizado. O objetivo deste trabalho foi comparar a eficácia de um aparelho fotopolimerizador de diodos emissores de luz e a de um de luz halógena através do grau de penetração de um corante em uma resina composta micro-híbrida. A resina composta utilizada (Filtek Z250/3M Dental foi inserida em matrizes

  10. The Effect of Instructional Method on Cardiopulmonary Resuscitation Skill Performance: A Comparison Between Instructor-Led Basic Life Support and Computer-Based Basic Life Support With Voice-Activated Manikin.

    Science.gov (United States)

    Wilson-Sands, Cathy; Brahn, Pamela; Graves, Kristal

    2015-01-01

    Validating participants' ability to correctly perform cardiopulmonary resuscitation (CPR) skills during basic life support courses can be a challenge for nursing professional development specialists. This study compares two methods of basic life support training, instructor-led and computer-based learning with voice-activated manikins, to identify if one method is more effective for performance of CPR skills. The findings suggest that a computer-based learning course with voice-activated manikins is a more effective method of training for improved CPR performance.

  11. Reliability-Based Design of Coastal Structures

    DEFF Research Database (Denmark)

    Burcharth, H. F.

    1997-01-01

    is a combination of material presented in the following references: Burcharth, H.F. (1992) Reliability evaluation of a structure at sea. Proceedings of the Short Course on Design and Reliability of Coastal Structures. Venice, Scuola di S. Giovanni Evangelista, 1992. 23rd International Conference on Coastal...

  12. Examination of a Nurse-led Community-based Education and Coaching Intervention for Coronary Heart Disease High-risk Individuals in China

    Directory of Open Access Journals (Sweden)

    Yan-Jin Huang, RN, PhD

    2017-09-01

    Conclusion: A 6-month community-based intervention in a CHD high-risk population improved disease-related risk factors, depression, and HRQoL. Results provide preliminary evidence for primary prevention of cardiovascular disease risk in a community high-risk population.

  13. Photoreceptor spectral sensitivity of the compound eyes of black soldier fly (Hermetia illucens) informing the design of LED-based illumination to enhance indoor reproduction

    NARCIS (Netherlands)

    Oonincx, D.G.A.B.; Volk, N.; Diehl, J.J.E.; Loon, van J.J.A.; Belušič, G.

    2016-01-01

    Mating in the black soldier fly (BSF) is a visually mediated behaviour that under natural conditions occurs in full sunlight. Artificial light conditions promoting mating by BSF were designed based on the spectral characteristics of the compound eye retina. Electrophysiological measurements

  14. Advanced Cardiac Resuscitation Evaluation (ACRE: A randomised single-blind controlled trial of peer-led vs. expert-led advanced resuscitation training

    Directory of Open Access Journals (Sweden)

    Hughes Thomas C

    2010-01-01

    Full Text Available Abstract Background Advanced resuscitation skills training is an important and enjoyable part of medical training, but requires small group instruction to ensure active participation of all students. Increases in student numbers have made this increasingly difficult to achieve. Methods A single-blind randomised controlled trial of peer-led vs. expert-led resuscitation training was performed using a group of sixth-year medical students as peer instructors. The expert instructors were a senior and a middle grade doctor, and a nurse who is an Advanced Life Support (ALS Instructor. A power calculation showed that the trial would have a greater than 90% chance of rejecting the null hypothesis (that expert-led groups performed 20% better than peer-led groups if that were the true situation. Secondary outcome measures were the proportion of High Pass grades in each groups and safety incidents. The peer instructors designed and delivered their own course material. To ensure safety, the peer-led groups used modified defibrillators that could deliver only low-energy shocks. Blinded assessment was conducted using an Objective Structured Clinical Examination (OSCE. The checklist items were based on International Liaison Committee on Resuscitation (ILCOR guidelines using Ebel standard-setting methods that emphasised patient and staff safety and clinical effectiveness. The results were analysed using Exact methods, chi-squared and t-test. Results A total of 132 students were randomised: 58 into the expert-led group, 74 into the peer-led group. 57/58 (98% of students from the expert-led group achieved a Pass compared to 72/74 (97% from the peer-led group: Exact statistics confirmed that it was very unlikely (p = 0.0001 that the expert-led group was 20% better than the peer-led group. There were no safety incidents, and High Pass grades were achieved by 64 (49% of students: 33/58 (57% from the expert-led group, 31/74 (42% from the peer-led group. Exact

  15. Zernike polynomials for photometric characterization of LEDs

    International Nuclear Information System (INIS)

    Velázquez, J L; Ferrero, A; Pons, A; Campos, J; Hernanz, M L

    2016-01-01

    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. (paper)

  16. White LED phosphors: the next step

    Science.gov (United States)

    Yamamoto, Hajime

    2010-02-01

    Application of white LEDs is extended toward high-output light sources, e.g. for automotive headlights, and better spectral matching with optical filters for LCD backlighting. To meet such new demands, phosphor materials have been investigated with focus on their luminescence spectra, temperature characteristics and reliability. The conventional yellow phosphor based on Y3Al5O12:Ce3+ has excellent performance as a single phosphor combined with a blue LED. More recently developed nitrido- or oxonitrido-silicates activated with Eu2+ are also promising materials showing green to red luminescence depending on a composition and high thermal and chemical stability. And yet, demands for specific application have been made clear and strong. This paper reviews the present status and challenging goals of phosphors in the next stage further to make progress in white LEDs.

  17. Affordable underwater wireless optical communication using LEDs

    Science.gov (United States)

    Pilipenko, Vladimir; Arnon, Shlomi

    2013-09-01

    In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

  18. Optoelectronic Devices Based on Novel Semiconductor Structures

    National Research Council Canada - National Science Library

    Ding, Yujie

    1999-01-01

    .... We have implemented several new schemes for efficiently generating blue and green light. We have grown and characterized several structures towards optically-pumped three- and four-level intersubband lasers...

  19. Modal Based Fatigue Monitoring of Steel Structures

    DEFF Research Database (Denmark)

    Graugaard-Jensen, J.; Brincker, Rune; Hjelm, H. P.

    2005-01-01

    In this paper it is shown how the accumulated fatigue in steel structures can be estimated with high accuracy by continuously measuring the accelerations in a few points of the structure. First step is to obtain a good estimate of the mode shapes by performing a natural input modal analysis. The so...... the damage forecasted by commonly accepted design rules. This points to possibilities of significantly increasing the fatigue lives of structures by performing continuous monitoring....... obtained mode shapes are then used to calibrate a Finite Element model of the structure and to obtain the modal coordinates of the active modes by inverting the mode shape matrix. If the number of active modes is smaller than the number of measurement points, then the problem is solved by regression...

  20. Structure-based drug design of a highly potent CDK1,2,4,6 inhibitor with novel macrocyclic quinoxalin-2-one structure.

    Science.gov (United States)

    Kawanishi, Nobuhiko; Sugimoto, Tetsuya; Shibata, Jun; Nakamura, Kaori; Masutani, Kouta; Ikuta, Mari; Hirai, Hiroshi

    2006-10-01

    The design of a novel series of cyclin-dependent kinase (CDK) inhibitors containing a macrocyclic quinoxaline-2-one is reported. Structure-based drug design and optimization from the starting point of diarylurea 2, which we previously reported as a moderate CDK1,2,4,6 inhibitor [J. Biol.Chem.2001, 276, 27548], led to the discovery of potent CDK1,2,4,6 inhibitor that were suitable for iv administration for in vivo study.

  1. ‘We are a community [but] that takes a certain amount of energy’: Exploring shared visions, social action, and resilience in place-based community-led energy initiatives

    International Nuclear Information System (INIS)

    Parkhill, K.A.; Shirani, F.; Butler, C.; Henwood, K.L.; Groves, C.; Pidgeon, N.F.

    2015-01-01

    Highlights: • We engage with conceptual characteristics of 3 community-led energy case studies. • We examine data from interviews to explore the issues community energy groups face. • Shared visions, social action and social resilience are important to community energy. • Creating and maintaining shared visions, social action and social resilience is extremely challenging. - Abstract: In UK energy policy, community-led energy initiatives are increasingly being imbued with transformative power to facilitate low carbon transitions. The ways that such expectations for communities are manifesting in practice remains, however, relatively poorly understood. In particular, key conceptual developments in unpacking what constitutes ‘community’ that highlight the significance of ‘place’ along with important characteristics, such as shared visions, collective social action, and resilience, have yet to be comprehensively explored in the context of community-led energy initiatives. This paper uses an interpretive stance to engage with these conceptual ideas about community and provides insights into the nature of community and its meaning for developing energy-related initiatives and realising the wider goals of energy policy. The paper draws on data from in-depth qualitative, longitudinal interviews undertaken in two residential communities and one purely workplace-based community, which are engaged in community energy initiatives. We argue that there are difficulties and ambiguities in creating shared visions, achieving social action, and developing resilience that are related to the specificities of community in place, but that all three characteristics are likely to be important for the making of sustainable places

  2. Distributed Prognostics Based on Structural Model Decomposition

    Data.gov (United States)

    National Aeronautics and Space Administration — Within systems health management, prognostics focuses on predicting the remaining useful life of a system. In the model-based prognostics paradigm, physics-based...

  3. Reliability based Robustness of Timber Structures through NDT Data Updating

    DEFF Research Database (Denmark)

    Sousa, Hélder S.; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning

    2011-01-01

    This work presents a framework for reliability-based assessment of timber structures / members using data gathered from non-destructive test results. These results are used for modeling an update of the mechanical characteristics of timber, using Bayesian methods. Results gathered from ultrasound...... of the structure, thus, being possible to evaluate reliability based in time dependent factors, as well to categorize that structure in terms of robustness. For exemplification of the underlined concepts, three different types of structures are studied....

  4. Sustaining Nurse-Led Task-Shifting Strategies for Hypertension Control: A Concept Mapping Study to Inform Evidence-Based Practice.

    Science.gov (United States)

    Blackstone, Sarah; Iwelunmor, Juliet; Plange-Rhule, Jacob; Gyamfi, Joyce; Quakyi, Nana Kofi; Ntim, Micheal; Ogedegbe, Gbenga

    2017-10-01

    The use of task-shifting is an increasingly widespread delivery approach for health interventions targeting prevention, treatment, and control of hypertension in adults living in sub-Saharan Africa (SSA). Addressing a gap in the literature, this research examined the sustainability of an ongoing task-shifting strategy for hypertension (TASSH) from the perspectives of community health nurses (CHNs) implementing the program. We used concept-mapping, a mixed-methods participatory approach to understand CHNs' perceptions of barriers and enablers to sustaining a task-shifting program. Participants responded to focal prompts, eliciting statements regarding perceived barriers and enablers to sustaining TASSH, and then rated these ideas based on importance to the research questions and feasibility to address. Twenty-eight community health nurses (21 women, 7 men) from the Ashanti region of Ghana completed the concept-mapping process. Factors influencing sustainability were grouped into five categories: Limited Drug Supply, Financial Support, Provision of Primary Health Care, Personnel Training, and Patient-Provider Communication. The limited supply of antihypertensive medication was considered by CHNs as the most important item to address, while providing training for intervention personnel was considered most feasible to address. This study's findings highlight the importance of examining nurses' perceptions of factors likely to influence the sustainability of evidence-based, task-shifting interventions. Nurses' perceptions can guide the widespread uptake and dissemination of these interventions in resource-limited settings. © 2017 Sigma Theta Tau International.

  5. Control of two-dimensional growth of AlN and high Al-content AlGaN-based MQWs for deep-UV LEDs

    Directory of Open Access Journals (Sweden)

    Weihuang Yang

    2013-05-01

    Full Text Available Dense and atomically flat AlN film with root-mean-square roughness value of 0.32 nm was grown on sapphire substrate at a relatively lower temperature by using a three-step epitaxy technique. On the basis of this AlN template, AlGaN-based multiple quantum wells (MQWs with atomically flat hetero-interfaces were epitaxially grown to suppress nonradiative recombination by introducing In as a surfactant during simultaneous source supply. As a result, single intense- and narrow-peaked photoluminescence was obtained from the MQWs. Finally, the deep ultraviolet light emitting diodes with well-behaved I-V characteristic and strong electroluminescence in the range of 256–312 nm were fabricated successfully.

  6. Multicenter randomized trial of centralized nurse-led telephone-based care coordination to improve outcomes after surgical resection for colorectal cancer: the CONNECT intervention.

    Science.gov (United States)

    Young, Jane M; Butow, Phyllis N; Walsh, Jennifer; Durcinoska, Ivana; Dobbins, Timothy A; Rodwell, Laura; Harrison, James D; White, Kate; Gilmore, Andrew; Hodge, Bruce; Hicks, Henry; Smith, Stephen; O'Connor, Geoff; Byrne, Christopher M; Meagher, Alan P; Jancewicz, Stephen; Sutherland, Andrew; Ctercteko, Grahame; Pathma-Nathan, Nimalan; Curtin, Austin; Townend, David; Abraham, Ned S; Longfield, Greg; Rangiah, David; Young, Christopher J; Eyers, Anthony; Lee, Peter; Fisher, Dean; Solomon, Michael J

    2013-10-01

    To investigate the effectiveness of a centralized, nurse-delivered telephone-based service to improve care coordination and patient-reported outcomes after surgery for colorectal cancer. Patients with a newly diagnosed colorectal cancer were randomly assigned to the CONNECT intervention or usual care. Intervention-group patients received standardized calls from the centrally based nurse 3 and 10 days and 1, 3, and 6 months after discharge from hospital. Unmet supportive care needs, experience of care coordination, unplanned readmissions, emergency department presentations, distress, and quality of life (QOL) were assessed by questionnaire at 1, 3, and 6 months. Of 775 patients treated at 23 public and private hospitals in Australia, 387 were randomly assigned to the intervention group and 369 to the control group. There were no significant differences between groups in unmet supportive care needs, but these were consistently low in both groups at both follow-up time points. There were no differences between the groups in emergency department presentations (10.8% v 13.8%; P = .2) or unplanned hospital readmissions (8.6% v 10.5%; P = .4) at 1 month. By 6 months, 25.6% of intervention-group patients had reported an unplanned readmission compared with 27.9% of controls (P = .5). There were no significant differences in experience of care coordination, distress, or QOL between groups at any follow-up time point. This trial failed to demonstrate substantial benefit of a centralized system to provide standardized, telephone follow-up for postoperative patients with colorectal cancer. Future interventions could investigate a more tailored approach.

  7. White LED motorcycle headlamp design

    Science.gov (United States)

    Sun, Wen-Shing

    2015-09-01

    The motorcycle headlamp is composed of a white LED module, an elliptical reflector, a parabolic reflector and a toric lens. We use non-sequential ray to improve the optical efficiency of the compound reflectors. Using the toric lens can meet ECE_113 regulation and obtain a good uniformity.

  8. UV-LED photopolymerised monoliths

    Czech Academy of Sciences Publication Activity Database

    Abele, S.; Nie, F.; Foret, František; Paull, B.; Macka, M.

    2008-01-01

    Roč. 133, č. 7 (2008), s. 864-866 ISSN 0003-2654 R&D Projects: GA AV ČR KAN400310651 Institutional research plan: CEZ:AV0Z40310501 Keywords : photopolymerisation * UV-LED * polymethacrylate monolith Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.761, year: 2008

  9. Architecture-Led Safety Process

    Science.gov (United States)

    2016-12-01

    Contents Acknowledgments iv Abstract v 1 Introduction 1 2 Architecture -Led Processes and ALSA 2 3 ALSA Practices 5 3.1 Example System 8 4 Identify... Architecture Models 13 5 Identify Operational Hazards and Hazard Contributors 15 5.1 System Partitioning 15 5.2 Operational Context as a Control

  10. Testing of a simplified LED based vis/NIR system for rapid ripeness evaluation of white grape (Vitis vinifera L.) for Franciacorta wine.

    Science.gov (United States)

    Giovenzana, Valentina; Civelli, Raffaele; Beghi, Roberto; Oberti, Roberto; Guidetti, Riccardo

    2015-11-01

    The aim of this work was to test a simplified optical prototype for a rapid estimation of the ripening parameters of white grape for Franciacorta wine directly in field. Spectral acquisition based on reflectance at four wavelengths (630, 690, 750 and 850 nm) was proposed. The integration of a simple processing algorithm in the microcontroller software would allow to visualize real time values of spectral reflectance. Non-destructive analyses were carried out on 95 grape bunches for a total of 475 berries. Samplings were performed weekly during the last ripening stages. Optical measurements were carried out both using the simplified system and a portable commercial vis/NIR spectrophotometer, as reference instrument for performance comparison. Chemometric analyses were performed in order to extract the maximum useful information from optical data. Principal component analysis (PCA) was performed for a preliminary evaluation of the data. Correlations between the optical data matrix and ripening parameters (total soluble solids content, SSC; titratable acidity, TA) were carried out using partial least square (PLS) regression for spectra and using multiple linear regression (MLR) for data from the simplified device. Classification analysis were also performed with the aim of discriminate ripe and unripe samples. PCA, MLR and classification analyses show the effectiveness of the simplified system in separating samples among different sampling dates and in discriminating ripe from unripe samples. Finally, simple equations for SSC and TA prediction were calculated. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Structuring AHP-based maintenance policy selection

    NARCIS (Netherlands)

    Goossens, Adriaan; Basten, Robertus Johannes Ida; Hummel, J. Marjan; van der Wegen, Leonardus L.M.

    2015-01-01

    We aim to structure the maintenance policy selection process for ships, using the Analytic Hierarchy Process (AHP). Maintenance is an important contributor to reach the intended life-time of capital technical assets, and it is gaining increasing interest and relevance. A maintenance policy is a

  12. Base connections for signal/sign structures.

    Science.gov (United States)

    2012-02-01

    The Atlantic hurricane season of 2004 brought with it a series of four major hurricanes that made landfall across : Florida within a six-week period. During this time, a number of cantilever sign structures along the state interstate system : failed....

  13. Nitride-based Quantum-Confined Structures for Ultraviolet-Visible Optical Devices on Silicon Substrates

    KAUST Repository

    Janjua, Bilal

    2017-04-01

    III–V nitride quantum-confined structures embedded in nanowires (NWs), also known as quantum-disks-in-nanowires (Qdisks-in-NWs), have recently emerged as a new class of nanoscale materials exhibiting outstanding properties for optoelectronic devices and systems. It is promising for circumventing the technology limitation of existing planar epitaxy devices, which are bounded by the lattice-, crystal-structure-, and thermal- matching conditions. This work presents significant advances in the growth of good quality GaN, InGaN and AlGaN Qdisks-in-NWs based on careful optimization of the growth parameters, coupled with a meticulous layer structure and active region design. The NWs were grown, catalyst-free, using plasma assisted molecular beam epitaxy (PAMBE) on silicon (Si) substrates. A 2-step growth scheme was developed to achieve high areal density, dislocation free and vertically aligned NWs on Ti/Si substrates. Numerical modeling of the NWs structures, using the nextnano3 software, showed reduced polarization fields, and, in the presence of Qdisks, exhibited improved quantum-confinement; thus contributing to high carrier radiative-recombination rates. As a result, based on the growth and device structure optimization, the technologically challenging orange and yellow NWs light emitting devices (LEDs) targeting the ‘green-yellow’ gap were demonstrated on scalable, foundry compatible, and low-cost Ti coated Si substrates. The NWs work was also extended to LEDs emitting in the ultraviolet (UV) range with niche applications in environmental cleaning, UV-curing, medicine, and lighting. In this work, we used a Ti (100 nm) interlayer and Qdisks to achieve good quality AlGaN based UV-A (320 - 400 nm) device. To address the issue of UV-absorbing polymer, used in the planarization process, we developed a pendeo-epitaxy technique, for achieving an ultra-thin coalescence of the top p-GaN contact layer, for a self-planarized Qdisks-in-NWs UV-B (280 – 320 nm) LED grown

  14. Availability of volunteer-led home-based care system and baseline factors as predictors of clinical outcomes in HIV-infected patients in rural Zambia.

    Directory of Open Access Journals (Sweden)

    Christopher B Estopinal

    Full Text Available We assessed the impact of home-based care (HBC for HIV+ patients, comparing outcomes between two groups of Zambians receiving antiretroviral therapy (ART who lived in villages with and without HBC teams.We conducted a retrospective cohort study using medical charts from Macha Mission Hospital, a hospital providing HIV care in Zambia's rural Southern Province. Date of birth, date of ART initiation, place of residence, sex, body mass index (BMI, CD4+ cell count, and hemoglobin (Hgb were abstracted. Logistic regression was used to test our hypothesis that HBC was associated with treatment outcomes.Of 655 patients, 523 (80% were eligible and included in the study. There were 428 patients (82% with favorable outcomes (alive and on ART and 95 patients (18% with unfavorable outcomes (died, lost to follow-up, or stopped treatment. A minority of the 523 eligible patients (n = 84, 16% lived in villages with HBC available. Living in a village with HBC was not significantly associated with treatment outcomes; 80% of patients in a village with HBC had favorable outcomes, compared to 82% of patients in a village without HBC (P = 0.6 by χ(2. In bivariable analysis, lower BMI (P<0.001, low CD4+ cell count (P = 0.02, low Hgb concentration (P = 0.02, and older age at ART initiation (P = 0.047 were associated with unfavorable outcomes. In multivariable analysis, low BMI remained associated with unfavorable outcomes (P<0.001.We did not find that living in a village with HBC available was associated with improved treatment outcomes. We speculate that the ART clinic's rigorous treatment preparation before ART initiation and continuous adherence counseling during ART create a motivated group of patients whose outcomes did not improve with additional HBC support. An alternative explanation is that the quality of the HBC program is suboptimal.

  15. A Novel Structure for MEMS Based Varactors

    Directory of Open Access Journals (Sweden)

    Ebrahim Abbaspour-Sani

    2006-08-01

    Full Text Available A novel structure with electro-mechanically tunable capacitor for RF application is presented. The suspended electrodes are designed in such a way that both are electrostaticaly displaceable. This double plate moveability feature of the capacitor increases the tuning range. In this structure, there is no need for cantilever beams, which introduce considerable series resistance to the capacitor and decrease the quality factor. Therefore, our proposed varactor achieves better Q in a smaller area. The simulated one pF capacitor shows a Q of 40 at 1 GHz and a tuning range of 42%. Pull-in voltage is 3.6 V, which is a reasonable value for submicron CMOS technologies.

  16. LED lamp power management system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A. M.

    2013-03-19

    An LED lamp power management system and method including an LED lamp having an LED controller 58; a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 reduces power loss in one of the channel switch 62 and the shunt switch 68 when LED lamp electronics power loss (P.sub.loss) exceeds an LED lamp electronics power loss limit (P.sub.lim); and each of the channel switches 62 receives a channel switch control signal 63 from the LED controller 58 and each of the shunt switches 68 receives a shunt switch control signal 69 from the LED controller 58.

  17. LED lamp color control system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A.M.

    2013-02-05

    An LED lamp color control system and method including an LED lamp having an LED controller 58; and a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 determines whether the LED source 80 is in a feedback controllable range, stores measured optical flux for the LED source 80 when the LED source 80 is in the feedback controllable range, and bypasses storing the measured optical flux when the LED source 80 is not in the feedback controllable range.

  18. Uniform LED illuminator for miniature displays

    Science.gov (United States)

    Medvedev, Vladimir; Pelka, David G.; Parkyn, William A.

    1998-10-01

    The Total Internally Reflecting (TIR) lens is a faceted structure composed of prismatic elements that collect a source's light over a much larger angular range than a conventional Fresnel lens. It has been successfully applied to the efficient collimation of light from incandescent and fluorescent lamps, and from light-emitting diodes (LEDs). A novel LED-powered collimating backlight is presented here, for uniformly illuminating 0.25'-diagonal miniature liquid- crystal displays, which are a burgeoning market for pagers, cellular phones, digital cameras, camcorders, and virtual- reality displays. The backlight lens consists of a central dual-asphere refracting section and an outer TIR section, properly curved with a curved exit face.

  19. CSTutor: A Sketch-Based Tool for Visualizing Data Structures

    Science.gov (United States)

    Buchanan, Sarah; Laviola, Joseph J., Jr.

    2014-01-01

    We present CSTutor, a sketch-based interface designed to help students understand data structures, specifically Linked Lists, Binary Search Trees, AVL Trees, and Heaps. CSTutor creates an environment that seamlessly combines a user's sketched diagram and code. In each of these data structure modes, the user can naturally sketch a data structure on…

  20. The effectiveness and safety of topical PhotoActif phosphatidylcholine-based anti-cellulite gel and LED (red and near-infrared) light on Grade II-III thigh cellulite: a randomized, double-blinded study.

    Science.gov (United States)

    Sasaki, Gordon H; Oberg, Kerby; Tucker, Barbara; Gaston, Margaret

    2007-06-01

    Cellulite of the upper lateral and posterior thighs and lower buttocks represents a common, physiological and unwanted condition whose etiologies and effective management are subjects of continued debate. The purpose of this controlled, double-blinded study is to evaluate the efficacy and safety of a novel phosphatidylcholine-based, cosmeceutical anti-cellulite gel combined with a light-emitting diode (LED) array at the wavelengths of red (660 nm) and near-infrared (950 nm), designed to counter the possible mechanisms that purportedly accentuate the presence of thigh cellulite. Nine healthy female volunteers with Grade II-III thigh cellulite were randomly treated twice daily with an active gel on one thigh and a placebo gel on the control thigh for 3 months. Twice weekly, each thigh was exposed for a 15-minute treatment with LED light for a total of 24 treatments. At 0, 6, and 12 weeks of the study the following clinical determinants were obtained: standardized digital photography, height and weight measurements, standardized thigh circumference tape measurements, pinch testing, body mass index (kg/m2), body fat analysis (Futrex-5500/XL near-infrared analyzer), and digital high-resolution ultrasound imaging of the dermal-adiposal border. In selected patients, full-thickness biopsies of the placebo and active-treated sites were obtained. At 18 months, repeat standardized digital photography, height and weight measurements, and body mass index measurements were obtained. At the end of 3 months, eight of nine thighs treated with the phosphatidylcholine-based, anti-cellulite gel and LED treatments were downgraded to a lower cellulite grade by clinical examination, digital photography, and pinch test assessment. Digital ultrasound at the dermal-adiposal interface demonstrated not only a statistically significant reduction of immediate hypodermal depth, but also less echo-like intrusions into the dermal layer. Three of six biopsies from thighs treated for 3 months with

  1. Celebrity-led development organisations

    DEFF Research Database (Denmark)

    Budabin, Alexandra Cosima; Rasmussen, Louise Mubanda; Richey, Lisa Ann

    2017-01-01

    The past decade has seen a frontier open up in international development engagement with the entrance of new actors such as celebrity-led organisations. We explore how such organisations earn legitimacy with a focus on Madonna’s Raising Malawi and Ben Affleck’s Eastern Congo Initiative. The study...... draws from organisational materials, interviews, mainstream news coverage, and the texts of the celebrities themselves to investigate the construction of authenticity, credibility, and accountability. We find these organisations earn legitimacy and flourish rapidly amid supportive elite networks...... for funding, endorsements, and expertise. We argue that the ways in which celebrity-led organisations establish themselves as legitimate development actors illustrate broader dynamics of the machinery of development....

  2. Strengthening of Concrete Structures with cement based bonded composites

    DEFF Research Database (Denmark)

    Täljsten, Björn; Blanksvärd, Thomas

    2008-01-01

    Due to demands on higher loads, degradation, re-construction etc. there is a constant need for repair or strengthening of existing concrete structures. Many varying methods exist to strengthen concrete structures, one such commonly used technique utilizes surface epoxy bonded FRPs (Fibre Reinforced...... with improved working environment and better compatibility to the base concrete structure. This study gives an overview of different cement based systems, all with very promising results for structural upgrading. Studied parameters are structural retrofit for bending, shear and confinement. It is concluded...

  3. MOVPE and characterization of GaN-based structures on alternative substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dikme, Y.

    2006-06-20

    This study involves growth experiments of GaN-based layer structures on silicon (Si), lithium aluminate (LiAlO{sub 2}) and the composite substrate SiCOI. Substrate specific preparation and growth procedures were developed. Because of the different lattice constants and thermal expansion coefficients between GaN and the substrate materials and because of the high depositions temperatures (>1000 C) complex interlayers are required to create a crossover from the substrate to the GaN layer and to prevent substrate/layer bowing and cracks developing in the epitaxial layers. Crystallographic, thermal and electronic properties of these materials were investigated and the developed layers were used as buffer layers for electronic and opto electronic devices. On Si AlN/GaN distributed Bragg reflectors (DBR), InGaN/GaN multiple quantum well (MQW) and AlGaN/GaN HEMT (high electron mobility transistor) were demonstrated. The transistor structures showed high power densities, which were comparable to industrially fabricated devices. As well as the reflection of a certain wavelength region, the DBR layers additionally showed positive influence on succeeding GaN top layer optical properties. For the first time laser emission of an optically pumped InGaN/GaN MQW on Si was demonstrated with low excitation density and a high operating temperature. GaN-based structures were deposited on LiAlO2 in the m-plane crystal orientation; that do not exhibit polarization mechanisms in growth direction. For the deposition of coalesced GaN films a seal-coating of the LiAlO{sub 2} surface was developed and finally LED structures were grown on these substrates. For the first time electroluminescence of LED structures on LiAlO{sub 2} was achieved. The growth on the composite substrate SiCOI was initiated with an HT AlN layer and it was demonstrated that SiCOI is comparable to a bulk SiC substrate for the GaN-based epitaxy. The developed and investigated layer structure served as buffer for the

  4. Structural Bases of Postresuscitative Heart Failure

    Directory of Open Access Journals (Sweden)

    V. T. Dolgikh

    2005-01-01

    Full Text Available An experiment on 106 non-inbred male albino rats undergone 4-minute clinical death from acute blood loss has revealed that the first three days after resuscitation are marked by a concomitance of vascular disorders and cardiomyocytic dystrophic changes, the leading role being played by sludge, stasis, thrombosis, increased vascular permeability, perivascular edema, and hemorrhages. Cardiomyocytic destruction (various contractures, block-like myofibrillolysis, myocytoly-sis is a structural basis of postresuscitative heart failure. Three days later the heart displayed concomitant processes of recovery and damage. Three types of cardiac morphological changes have been identified in relation to the ratio of these processes.

  5. Structure-based bayesian sparse reconstruction

    KAUST Repository

    Quadeer, Ahmed Abdul

    2012-12-01

    Sparse signal reconstruction algorithms have attracted research attention due to their wide applications in various fields. In this paper, we present a simple Bayesian approach that utilizes the sparsity constraint and a priori statistical information (Gaussian or otherwise) to obtain near optimal estimates. In addition, we make use of the rich structure of the sensing matrix encountered in many signal processing applications to develop a fast sparse recovery algorithm. The computational complexity of the proposed algorithm is very low compared with the widely used convex relaxation methods as well as greedy matching pursuit techniques, especially at high sparsity. © 1991-2012 IEEE.

  6. Automotive LED lamp lighted appearance

    Science.gov (United States)

    Conn, Lawrence G.; Bennett, Larry R.

    2001-05-01

    The automotive optical engineer has an entirely new set of rules to follow for a 'smooth lighted appearance' with the introduction of LEDs into the automotive signal lighting market. To move away from the 'polka-dot' appearance long associated with the usage of LEDs as the light source for automotive lighting, and give the consumer a smooth lighted appearance to his lamp, there are several optical parameters that must be observed. The number and type of LEDs used, the size of the optical elements used, the spacing of the optical elements, plus many other factors all play a critical role and must be considered in the solution to the 'smooth lighted appearance' in an automotive signal lamp. The 'smooth lighted appearance' in an automotive signal lamp has long been a difficult problem to which there is more than one solution. The most visually pleasing and effective solution is not always the most easily obtainable solution since photometry requirements and smooth lighted appearance can be diametric goals. Subsequently the most cost effective and the easily 'doable' solution may not give the ultimate in aesthetically pleasing results for the consumer. Therefore, it is the purpose and intent of this paper to outline the parameters that need to be considered to obtain a 'smooth lighted appearance' for an automotive signal lamp, and to clarify the methods and 'tools' that are required to meet this goal.

  7. Benefits of Risk Based Inspection Planning for Offshore Structures

    DEFF Research Database (Denmark)

    Straub, D.M.; Goyet, J.; Sørensen, John Dalsgaard

    2006-01-01

    The economical benefits of applying risk-based inspection planning (RBI) for offshore structures subject to fatigue are evaluated based on experiences from past industrial projects. To this end, the factors influencing the cost of inspection, repair and failure of structures are discussed......, the financial benefit of RBI is assessed....

  8. Base pairing in RNA structures: A computational analysis of ...

    Indian Academy of Sciences (India)

    The base pairing patterns in RNA structures are more versatile and completely different as compared to DNA. We present here results of ab-initio studies of structures and interaction energies of eight selected RNA base pairs reported in literature. Interaction energies, including BSSE correction, of hydrogen added crystal ...

  9. [Structuralization of digestive endoscopy report based on NLP].

    Science.gov (United States)

    Kong, Xiao-feng; Li, Ying; Li, Hao-min; Lu, Xu-dong

    2008-09-01

    This paper presents a method based on NLP to realize structuralization of digestive endoscopy reports. The method is taking advantage of existing NLP's processing technologies and introducing minimal standard terminology (MST) to transform a narrative gastroscopy report into the structuralization report based on MST, whose accuracy rate is 92.3%.

  10. Base pairing in RNA structures: A computational analysis

    Indian Academy of Sciences (India)

    The base pairing patterns in RNA structures are more versatile and completely different as compared to DNA. We present here results of ab-initio studies of structures and interaction energies of eight selected RNA base pairs reported in literature. Interaction energies, including BSSE correction, of hydrogen added crystal ...

  11. Sustainable LED Fluorescent Light Replacement Technology

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2011-09-30

    Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life: Environmental Impact Review – Designs are comparable

  12. Lampu Pintar Berbasis LED Dengan Multi Sensor

    OpenAIRE

    Ramdan, Ade; Prajitno, Dicky Rianto; Herlan, Herlan; Gojali, Elli Ahmad

    2013-01-01

    In this paper, we propose a LED-based smart lamp prototype that integrated with sensor. The smart lamp use information of people and lighting confirmation, to turn on or turn off the lamp automatically. In addition, the sensor calculates and balances flash and ambient light exposure to decrease the light, so that can make energy efficiently in use. PIR (Passive Infrared Receiver) and Ultrasonic sensor is preferred to detect people condition in one place and LDR (Light Dependent Resistant) is ...

  13. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    pounds [2,3] renewed great interest in the study of high-temperature superconductivity. Fe-based systems are significantly different from the cuprates. The parent compounds in cuprates are antiferromagnetic Mott insulators, where the insulating property arises due to strong electron correlation compared to the width of their ...

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

    Science.gov (United States)

    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.

  15. Study on luminescence and thermal stability of blue-emitting Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}phosphor for application in InGaN-based LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Zhang, Zhi-Ming [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wu, Zhan-Chao, E-mail: wuzhan_chao@163.com [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wang, Fang-Fang [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Li, Zhen-Jiang, E-mail: zjli126@126.com [State Key Laboratory Base of Eco-chemical Engineering, College of Sino-German Science and Technology, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, Shandong (China)

    2017-07-15

    Highlights: • A blue phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} was prepared at low temperature of 800 °C. • The broad excitation band of the phosphor matches well with NUV LED chips. • The phosphor shows high color purity and good color stability. • A bright blue-emitting LED was fabricated with this phosphor on an InGaN chip. - Abstract: A series of blue-emitting phosphors Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} were synthesized by traditional high temperature solid-state reaction method. The micro-morphology and photoluminescence properties of the phosphors were investigated. The Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors exhibit broad excitation spectra ranging from 250 to 420 nm, and an intense asymmetric blue emission band peaking at 435 nm. Two different Eu{sup 2+} emission centers in Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were confirmed via their fluorescence properties. The concentration quenching mechanism, fluorescence lifetime and thermal stability of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were studied in detail. The thermal stability can be improved obviously by anion substitution. The CIE chromaticity coordinates of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors with different Eu{sup 2+}-doped concentrations were calculated. A blue light-emitting diode was fabricated by combination of a 370 nm InGaN chip and the prepared phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}. The present work suggests that Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} is a potential phosphor applied in InGaN-based LEDs.

  16. Crystalline Structure of Starch Based Nano Composites

    OpenAIRE

    Farid Amidi Fazli; Afshin Babazadeh; Farnaz Amidi Fazli

    2015-01-01

    In contrast with literal meaning of nano, researchers have been achieved mega adventures in this area and every day more nanomaterials are being introduced to the market. After long time application of fossil-based plastics, nowadays accumulation of their waste seems to be a big problem to the environment. On the other hand, mankind has more attention to safety and living environment. Replacing common plastic packaging materials with degradable ones that degrade faster an...

  17. Protocol for the PINCER trial: a cluster randomised trial comparing the effectiveness of a pharmacist-led IT-based intervention with simple feedback in reducing rates of clinically important errors in medicines management in general practices

    Directory of Open Access Journals (Sweden)

    Murray Scott A

    2009-05-01

    Full Text Available Abstract Background Medication errors are an important cause of morbidity and mortality in primary care. The aims of this study are to determine the effectiveness, cost effectiveness and acceptability of a pharmacist-led information-technology-based complex intervention compared with simple feedback in reducing proportions of patients at risk from potentially hazardous prescribing and medicines management in general (family practice. Methods Research subject group: "At-risk" patients registered with computerised general practices in two geographical regions in England. Design: Parallel group pragmatic cluster randomised trial. Interventions: Practices will be randomised to either: (i Computer-generated feedback; or (ii Pharmacist-led intervention comprising of computer-generated feedback, educational outreach and dedicated support. Primary outcome measures: The proportion of patients in each practice at six and 12 months post intervention: - with a computer-recorded history of peptic ulcer being prescribed non-selective non-steroidal anti-inflammatory drugs - with a computer-recorded diagnosis of asthma being prescribed beta-blockers - aged 75 years and older receiving long-term prescriptions for angiotensin converting enzyme inhibitors or loop diuretics without a recorded assessment of renal function and electrolytes in the preceding 15 months. Secondary outcome measures; These relate to a number of other examples of potentially hazardous prescribing and medicines management. Economic analysis: An economic evaluation will be done of the cost per error avoided, from the perspective of the UK National Health Service (NHS, comparing the pharmacist-led intervention with simple feedback. Qualitative analysis: A qualitative study will be conducted to explore the views and experiences of health care professionals and NHS managers concerning the interventions, and investigate possible reasons why the interventions prove effective, or conversely prove

  18. How HIV-1 entry mechanism and broadly neutralizing antibodies guide structure-based vaccine design.

    Science.gov (United States)

    Pancera, Marie; Changela, Anita; Kwong, Peter D

    2017-05-01

    An HIV-1 vaccine that elicits broadly neutralizing antibodies (bNAbs) remains to be developed. Here, we review how knowledge of bNAbs and HIV-1 entry mechanism is guiding the structure-based design of vaccine immunogens and immunization regimens. Isolation of bNAbs from HIV-1-infected donors has led to an unprecedented understanding of the sites of vulnerability that these antibodies target on the HIV-1 envelope (Env) as well as of the immunological pathways that these antibody lineages follow to develop broad and potent neutralization. Sites of vulnerability, however, reside in the context of diverse Env conformations required for HIV-1 entry, including a prefusion-closed state, a single-CD4-bound intermediate, a three-CD4-bound intermediate, a prehairpin intermediate and postfusion states, and it is not always clear which structural state optimally presents a particular site of vulnerability in the vaccine context. Furthermore, detailed knowledge of immunological pathways has led to debate among vaccine developers as to how much of the natural antibody-developmental pathway immunogens should mimic, ranging from only the recognized epitope to multiple antigens from the antibody-virus coevolution process. A plethora of information on bNAbs is guiding HIV-1-vaccine development. We highlight consideration of the appropriate structural context from the HIV-1-entry mechanism and extraordinary progress with replicating template B-cell ontogenies.

  19. Measuring progress towards a primary care-led NHS.

    Science.gov (United States)

    Miller, P; Craig, N; Scott, A; Walker, A; Hanlon, P

    1999-07-01

    The push towards a 'primary care-led' National Health Service (NHS) has far-reaching implications for the future structure of the NHS. The policy involves both a growing emphasis on the role of primary care practitioners in the commissioning of health services, and a change from hospital to primary and community settings for a range of services and procedures. Although the terminology has changed, this emphasis remains in the recent Scottish Health Service White Paper and its English counterpart. To consider three questions in relation to this policy goal. First, does the evidence base support the changes? Secondly, what is the scale of the changes that have occurred? Thirdly, what are the barriers to the development of a primary care-led NHS? Programme budgets were compiled to assess changes over time in the balance of NHS resource allocation with respect to primary and secondary care. Total NHS revenue expenditure for the 15 Scottish health boards was grouped into four blocks or 'programmes': primary care, secondary care, community services, and a residual. The study period was 1991/2 to 1995/6. Expenditure data were supplied by the Scottish Office. Ambiguity of definitions and the absence of good data cause methodological difficulties in evaluating the scale and the appropriateness of the shift. The data that are available suggest that, at the aggregate level, there have been changes over time in the balance of resource allocation between care settings: relative investment into primary care has increased. It would appear that this investment is relatively small and from growth money rather than a 'shift' from secondary care. In addition, the impact of GP-led commissioning is variable but limited. General practitioners' (GPs') attitudes to the policy suggest that progress towards a primary care-led NHS will continue to be patchy. The limited shift to date, alongside evidence of ambivalent attitudes to the shift on the part of GPs, suggest that this is a policy

  20. Characteristics of white LED transmission through a smoke screen

    Science.gov (United States)

    Zheng, Yunfei; Yang, Aiying; Feng, Lihui; Guo, Peng

    2018-01-01

    The characteristics of white LED transmission through a smoke screen is critical for visible light communication through a smoke screen. Based on the Mie scattering theory, the Monte Carlo transmission model is established. Based on the probability density function, the white LED sampling model is established according to the measured spectrum of a white LED and the distribution angle of the lambert model. The sampling model of smoke screen particle diameter is also established according to its distribution. We simulate numerically the influence the smoke thickness, the smoke concentration and the angle of irradiance of white LED on transmittance of the white LED. We construct a white LED smoke transmission experiment system. The measured result on the light transmittance and the smoke concentration agreed with the simulated result, and demonstrated the validity of simulation model for visible light transmission channel through a smoke screen.

  1. A structural informatics approach to mine kinase knowledge bases.

    Science.gov (United States)

    Brooijmans, Natasja; Mobilio, Dominick; Walker, Gary; Nilakantan, Ramaswamy; Denny, Rajiah A; Feyfant, Eric; Diller, David; Bikker, Jack; Humblet, Christine

    2010-03-01

    In this paper, we describe a combination of structural informatics approaches developed to mine data extracted from existing structure knowledge bases (Protein Data Bank and the GVK database) with a focus on kinase ATP-binding site data. In contrast to existing systems that retrieve and analyze protein structures, our techniques are centered on a database of ligand-bound geometries in relation to residues lining the binding site and transparent access to ligand-based SAR data. We illustrate the systems in the context of the Abelson kinase and related inhibitor structures. 2009 Elsevier Ltd. All rights reserved.

  2. EVALUATING THE CULTURE-LED REGENERATION

    Directory of Open Access Journals (Sweden)

    D'Angelo Francesca

    2010-12-01

    Full Text Available The aim of the paper is to propose a new approach to urban planning, evaluating the culture-led regeneration processes. In the last few years, the cultural turn in urban planning played a central role in the urban studies. In this way we try to elaborate a more robust perspective interpreting the complex phenomenology emerging from the culture-led regeneration processes. Within the concept of complexity we discuss about the metabolic process that are the processes necessary to transform energy, material and information in goods and service functional to the complex urban system life. The approach that will be employed is the MuSIASEM that is based on several novel concept and an innovative methods never applied in this research field.

  3. Optical design of a LED searchlight system

    Science.gov (United States)

    Gong, Chen; Xu, Haiping; Liang, Jinhua; Liu, Yunfei; Yuan, Zengquan

    2018-01-01

    A 1200m visible searchlight system is designed based on photometry and application of geometric optics. To generate intensity distribution of this relatively powerful light beam we propose to use a high power LED and several refractive optical elements, which are composed of two plane-convex lenses and a conventional Fresnel lens. Two plane-convex lenses enable refraction of the side rays from the LED to the front direction which incident on the Fresnel lens. Fresnel lens, in its turn, concentrate the light flux and provide a nearly collimated beam to meet the requirement of forming a well-illuminated area across the road in the far field. Simulation data shows that this searchlight allow generating an appropriate illumination distribution for the long range requirements. A proof-of-concept prototype producing acceptable illuminance is developed.

  4. Distributed dimming control for LED lighting.

    Science.gov (United States)

    Lee, Sang Hyun; Kwon, Jae Kyun

    2013-11-04

    This paper presents a distributed energy-saving lighting strategy for the arrangements of a lighting network consisting of a group of light-emitting diode (LED) lamps and users. LED lamps have a dimming support feature to meet the illuminance requirements imposed by individual users. Both groups interact with each other via visible light communication (VLC) or other wireless communication features. This work aims to identify a configuration of lamps leading to the maximal energy saving in adaptive and distributed ways. To this end, a distributed assignment strategy is developed based on a message-passing framework where only local interactions among lamps and users are allowed for calculations and exchanges of the information on their status. The simulation results show that the proposed algorithm outperforms other distributed algorithms in a range of indoor lighting configurations.

  5. Interior LED Lighting Technology. Navy Energy Technology Validation (Techval) Program

    Science.gov (United States)

    2015-09-01

    evaluated using the Illumination Engineering Societies’ (IES) TM-21 manual. The TM- 21 manual provides a standardized method for evaluating when an LED...the equipment. The Cree luminaires installed in this study are rated for 75,000 hours of service, based on calculation methods that extrapolated...should be replaced with LED lamps. • Replace MR-16 lamps with LED lamps since this type of fixture is used to provide accent lighting and is

  6. Photochemical selectivity in guanine–cytosine base-pair structures

    Science.gov (United States)

    Abo-Riziq, Ali; Grace, Louis; Nir, Eyal; Kabelac, Martin; Hobza, Pavel; de Vries, Mattanjah S.

    2005-01-01

    Prebiotic chemistry presumably took place before formation of an oxygen-rich atmosphere and thus under conditions of intense short wavelength UV irradiation. Therefore, the UV photochemical stability of the molecular building blocks of life may have been an important selective factor in determining the eventual chemical makeup of critical biomolecules. To investigate the role of UV irradiation in base-pairing we have studied guanine (G) and cytosine (C) base pairs in the absence of the RNA backbone. We distinguished base-pair structures by IR–UV hole-burning spectroscopy as well as by high-level correlated ab initio calculations. The Watson–Crick structure exhibits broad UV absorption, in stark contrast to other GC structures and other base-pair structures. This broad absorption may be explained by a rapid internal conversion that makes this specific base pair arrangement uniquely photochemically stable. PMID:15618394

  7. Evaluating Functional and Structural Condition Based Maintenances of Airfield Pavements

    Directory of Open Access Journals (Sweden)

    Tarefder R.

    2013-01-01

    Full Text Available This study evaluates airfield pavements’ functional- and structural-condition to determine the most economical maintenance method. As a part of the analysis, Pavement Condition Index (PCI for several runways, taxiways, and aprons has been determined by MicroPAVER. Structural evaluation of airport pavements has been performed by Falling Weight Deflectometer (FWD test. Evaluation of Layer Moduli and Overlay Design (ELMOD also determines the required overlay thickness based on the E-values, i.e. FWD data analysis. Damage analysis determines the time of repeated overlay application. In addition, functional parameters have been included to determine the time of functional maintenance. Maintenance and rehabilitation alternatives have been selected to develop different program strategies. Life Cycle Cost Analysis (LCCA has been performed to determine the maintenance cost. Structural condition based maintenance cost is compared to functional condition based maintenance cost. Comparison shows that structural condition based approach yields cheaper maintenance strategies than functional condition based maintenance approach.

  8. Structural Health Monitoring Based on Combined Structural Global and Local Frequencies

    Directory of Open Access Journals (Sweden)

    Jilin Hou

    2014-01-01

    Full Text Available This paper presents a parameter estimation method for Structural Health Monitoring based on the combined measured structural global frequencies and structural local frequencies. First, the global test is experimented to obtain the low order modes which can reflect the global information of the structure. Secondly, the mass is added on the member of structure to increase the local dynamic characteristic and to make the member have local primary frequency, which belongs to structural local frequency and is sensitive to local parameters. Then the parameters of the structure can be optimized accurately using the combined structural global frequencies and structural local frequencies. The effectiveness and accuracy of the proposed method are verified by the experiment of a space truss.

  9. Technology Analysis of Global Smart Light Emitting Diode (LED Development Using Patent Data

    Directory of Open Access Journals (Sweden)

    Sangsung Park

    2017-08-01

    Full Text Available Technological developments related to smart light emitting diode (LED systems have progressed rapidly in recent years. In this paper, patent documents related to smart LED technology are collected and analyzed to understand the technology development of smart LED systems. Most previous studies of the technology were dependent on the knowledge and experience of domain experts, using techniques such as Delphi surveys or technology road-mapping. These approaches may be subjective and lack robustness, because the results can vary according to the selected expert groups. We therefore propose a new technology analysis methodology based on statistical modeling to obtain objective and relatively stable results. The proposed method consists of visualization based on Bayesian networks and a linear count model to analyze patent documents related to smart LED technology. Combining these results, a global hierarchical technology structure is created that can enhance the sustainability in smart LED system technology. In order to show how this methodology could be applied to real-world problems, we carry out a case study on the technology analysis of smart LED systems.

  10. Performance-based shape optimization of continuum structures

    International Nuclear Information System (INIS)

    Liang Qingquan

    2010-01-01

    This paper presents a performance-based optimization (PBO) method for optimal shape design of continuum structures with stiffness constraints. Performance-based design concepts are incorporated in the shape optimization theory to achieve optimal designs. In the PBO method, the traditional shape optimization problem of minimizing the weight of a continuum structure with displacement or mean compliance constraints is transformed to the problem of maximizing the performance of the structure. The optimal shape of a continuum structure is obtained by gradually eliminating inefficient finite elements from the structure until its performance is maximized. Performance indices are employed to monitor the performance of optimized shapes in an optimization process. Performance-based optimality criteria are incorporated in the PBO method to identify the optimum from the optimization process. The PBO method is used to produce optimal shapes of plane stress continuum structures and plates in bending. Benchmark numerical results are provided to demonstrate the effectiveness of the PBO method for generating the maximum stiffness shape design of continuum structures. It is shown that the PBO method developed overcomes the limitations of traditional shape optimization methods in optimal design of continuum structures. Performance-based optimality criteria presented can be incorporated in any shape and topology optimization methods to obtain optimal designs of continuum structures.

  11. Base pairing in RNA structures: A computational analysis of ...

    Indian Academy of Sciences (India)

    WINTEC

    PDB files using RASMOL18 software. Hydrogen atoms were added to these base pairs using MOLDEN19 software. The sugar portions attached to base pairs in. RNA structures were removed, and C1′ atoms were respectively replaced by hydrogen atoms during model building. The change in base pair geometry on re-.

  12. The Latent Structure of Secure Base Script Knowledge

    Science.gov (United States)

    Waters, Theodore E. A.; Fraley, R. Chris; Groh, Ashley M.; Steele, Ryan D.; Vaughn, Brian E.; Bost, Kelly K.; Veríssimo, Manuela; Coppola, Gabrielle; Roisman, Glenn I.

    2015-01-01

    There is increasing evidence that attachment representations abstracted from childhood experiences with primary caregivers are organized as a cognitive script describing secure base use and support (i.e., the "secure base script"). To date, however, the latent structure of secure base script knowledge has gone unexamined--this despite…

  13. A data base for aging of structural materials

    International Nuclear Information System (INIS)

    Oland, C.B.; Naus, D.J.; Jerath, S.

    1993-01-01

    The U.S. Nuclear Regulatory Commission (USNRC) initiated a Structural Aging (SAG) Program at the Oak Ridge National Laboratory (ORNL). The objective of the program is to provide assistance in identifying potential structural safety issues and to establish acceptance criteria for use in nuclear power plant evaluations for continued service. One of the main parts of the program focuses on the development of a Structural Materials Information Center where long-term and environment-dependent material properties are being collected and assembled into a data base. This data base is presented in two complementary formats. The Structural Materials Handbook is an expandable, hard-copy reference document that contains the complete data base for each material. The Structural Materials Electronic Data Base is accessible using an IBM-compatible personal computer. This paper presents an overview of the Structural Materials Information Center and briefly describes the features of the handbook and the electronic data base. In addition, a proposed method for using the data base to establish current property values for materials in existing concrete structures and to estimate the future performance of these materials is also presented. (author)

  14. A data base for aging of structural materials

    International Nuclear Information System (INIS)

    Oland, C.B.; Naus, D.J.; Jerath, S.

    1993-01-01

    USNRC initiated a Structural Aging (SAG) Program ORNL. The objective of the program is to provide assistance in identifying potential structural safety issues and to establish acceptance criteria for use in nuclear power plant evaluations for continued service. One main part focuses on the development of a Structural Materials Information Center where long-term and environment-dependent material properties are being collected and assembled into a data base. This data base is presented in two complementary formats. The Structural Materials Handbook is an expandable, hard-copy reference document that contains the complete data base for each material. The Structural Materials Electronic Data Base is accessible using an IBM-compatible personal computer. This paper presents an overview of the Structural Materials Information Center and briefly describes the features of the handbook and the electronic data base. In addition, a proposed method for using the data base to establish current property values for materials in existing concrete structures and to estimate the future performance of these materials is also presented

  15. Polylactide based nanocomposites: Processing, structure and performance relationship

    Science.gov (United States)

    Karami, Shahir

    The application of biodegradable polymers has been offered to the packing industry wishing to overcome the environmental consequence of employing the petroleum-based polymers. Furthermore, the unstable oil market urged the industry to look for the substitution of the renewable resources. Polylactide is known as the most popular biodegradable polymer developed on a large scale. Nevertheless, the growing contribution of polylactide to packing industry is somewhat restricted owing to its inherent brittleness and weak barrier properties. Therefore, the main objective of this thesis was defined to build a fundamental relationship between processing parameters and solid-state microstructure to improve the performance of polylactide. Polylactide nanocomposites were prepared through a multi-step melt compounding process. Dispersion of organically modified layered nanoparticles was detected by the WAXS and TEM characterizations, demonstrating the formation of intercalated nanocomposites. Relaxation spectrum exhibited the restricted dynamics of fraction of amorphous phase confined in polymer-particle interphase through dynamic rheological measurements. The fraction of rigid amorphous chains was estimated using TMDSC and DMA. This increased with nanoparticle content, levelling off upon the aggregation of nanoparticles. The annealing-induced molecular ordering was detected by FR-IR, increasing the rigid amorphous fraction. Cold crystallization was investigated during non-isothermal process using TMDSC. Crystallization kinetic was studied through the evaluation of Avrami parameters in isothermal process at the temperature range of Tg+30°C to Tg+70°C. The crystallization rate depressed with the nanoparticle content due to the enhanced fraction of rigid amorphous chains, as well as, the topological constraints derived from the formation of network structure. Nevertheless, the nanoparticles acted as heterogeneous nucleating sites upon devitrification of the rigid amorphous

  16. Low-Cost Illumination-Grade LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Epler, John [Philips Lumileds Lighting Company LLC, San Jose, CA (United States)

    2013-08-31

    Solid State Lighting is a cost-effective, energy-conserving technology serving a rapidly expand- ing multi-billion dollar market. This program was designed to accelerate this lighting revolution by reducing the manufacturing cost of Illumination-Grade LEDs. The technical strategy was to investigate growth substrate alternatives to standard planar sapphire, select the most effective and compatible option, and demonstrate a significant increase in Lumen/$ with a marketable LED. The most obvious alternate substrate, silicon, was extensively studied in the first two years of the program. The superior thermal and mechanical properties of Si were expected to improve wavelength uniformity and hence color yield in the manufacture of high-power illumination- grade LEDs. However, improvements in efficiency and epitaxy uniformity on standard c-plane sapphire diminished the advantages of switching to Si. Furthermore, the cost of sapphire decreased significantly and the cost of processing Si devices using our thin film process was higher than expected. We concluded that GaN on Si was a viable technology but not a practical option for Philips Lumileds. Therefore in 2012 and 2013, we sought and received amendments which broadened the scope to include other substrates and extended the time of execution. Proprietary engineered substrates, off-axis (non-c-plane) sapphire, and c-plane patterned sapphire substrates (PSS) were all investigated in the final 18 months of this program. Excellent epitaxy quality was achieved on all three candidates; however we eliminated engineered substrates and non-c-plane sapphire because of their higher combined cost of substrate, device fabrication and packaging. Ultimately, by fabricating a flip-chip (FC) LED based upon c-plane PSS we attained a 42% reduction in LED manufacturing cost relative to our LUXEON Rebel product (Q1-2012). Combined with a flux gain from 85 to 102 Lm, the LUXEON Q delivered a 210% increase in Lm/$ over this time period. The

  17. Enhanced light extraction of InGaN LEDs with photonic crystals grown on p-GaN using selective-area epitaxy and nanospherical-lens photolithography

    International Nuclear Information System (INIS)

    Zhao Linghui; Wei Tongbo; Wang Junxi; Zeng Yiping; Li Jinmin; Yan Qingfeng

    2013-01-01

    We report a new method for the fabrication of two-dimensional photonic crystal (PhC) hole arrays to improve the light extraction of GaN-based light-emitting diodes (LEDs). The PhC structures were realized using nanospherical-lens photolithography and the selective-area epitaxy method, which ensured the electrical properties of the LEDs through leaving the p-GaN damage-free. At a current of 350 mA, the light output power of LEDs with PhC hole arrays of 450 nm and 600 nm in diameter with the same lattice period of 900 nm were enhanced by 49.3% and 72.2%, respectively, compared to LEDs without a PhC. Furthermore, the LEDs with PhC hole structures showed an obviously smaller divergent angle compared with conventional LEDs, which is consistent with the results of finite-difference time-domain simulation. (semiconductor devices)

  18. Practical lighting design with LEDs

    CERN Document Server

    Lenk, Ron

    2011-01-01

    "This book covers all of the information needed to design LEDs into end-products. It is a practical guide, primarily explaning how things are done by practicing engineers. Equations are used only for practical calculations, and are kept to the level of high-school algebra. There are numerous drawings and schematics showing how things such as measurements are actually made, and showing curcuits that actually work. There are practical notes and examples embedded in the text that give pointers and how-to guides on many of the book's topics. After reading each chapter of the book, readers will have the knowledge to implement practical designs. This book will be kept as a reference tool for years to come"--

  19. Development of a Structure-Based Turbulence Model

    National Research Council Canada - National Science Library

    Reynolds, W

    2000-01-01

    Work in the current period was aimed at the construction of extensions of the structure-based Particle Representation and one-point models to flows with slow or moderate mean deformations and wall proximity effects...

  20. Global stability-based design optimization of truss structures using ...

    Indian Academy of Sciences (India)

    objective optimization; island models; genetic algorithm; arc-length method. ... Furthermore, a pure pareto-ranking based multi-objective optimization model is employed for the design optimization of the truss structure with multiple objectives.

  1. Protein structure-based design of anti-protozoal drugs

    Directory of Open Access Journals (Sweden)

    Verlinde Christophe L. M. J.

    2002-01-01

    Full Text Available The repertory of drugs to fight protozoal diseases such as malaria, Chagas' disease, leishmaniasis, and African trypanosomiasis is woefully inadequate. Now, genome sequencing and structural genomics projects are quickly elucidating new drug targets, providing incredible opportunities for medicinal chemists. Here, we illustrate the power of structure-based drug design in this process by our efforts to selectively block trypanosomal glycolysis.

  2. Polarity classification using structure-based vector representations of text

    NARCIS (Netherlands)

    Hogenboom, Alexander; Frasincar, Flavius; de Jong, Franciska M.G.; Kaymak, Uzay

    The exploitation of structural aspects of content is becoming increasingly popular in rule-based polarity classification systems. Such systems typically weight the sentiment conveyed by text segments in accordance with these segments' roles in the structure of a text, as identified by deep

  3. RNA structural motif recognition based on least-squares distance.

    Science.gov (United States)

    Shen, Ying; Wong, Hau-San; Zhang, Shaohong; Zhang, Lin

    2013-09-01

    RNA structural motifs are recurrent structural elements occurring in RNA molecules. RNA structural motif recognition aims to find RNA substructures that are similar to a query motif, and it is important for RNA structure analysis and RNA function prediction. In view of this, we propose a new method known as RNA Structural Motif Recognition based on Least-Squares distance (LS-RSMR) to effectively recognize RNA structural motifs. A test set consisting of five types of RNA structural motifs occurring in Escherichia coli ribosomal RNA is compiled by us. Experiments are conducted for recognizing these five types of motifs. The experimental results fully reveal the superiority of the proposed LS-RSMR compared with four other state-of-the-art methods.

  4. Probability based high temperature engineering creep and structural fire resistance

    CERN Document Server

    Razdolsky, Leo

    2017-01-01

    This volume on structural fire resistance is for aerospace, structural, and fire prevention engineers; architects, and educators. It bridges the gap between prescriptive- and performance-based methods and simplifies very complex and comprehensive computer analyses to the point that the structural fire resistance and high temperature creep deformations will have a simple, approximate analytical expression that can be used in structural analysis and design. The book emphasizes methods of the theory of engineering creep (stress-strain diagrams) and mathematical operations quite distinct from those of solid mechanics absent high-temperature creep deformations, in particular the classical theory of elasticity and structural engineering. Dr. Razdolsky’s previous books focused on methods of computing the ultimate structural design load to the different fire scenarios. The current work is devoted to the computing of the estimated ultimate resistance of the structure taking into account the effect of high temperatur...

  5. UV LED lighting for automated crystal centring

    International Nuclear Information System (INIS)

    Chavas, Leonard M. G.; Yamada, Yusuke; Hiraki, Masahiko; Igarashi, Noriyuki; Matsugaki, Naohiro; Wakatsuki, Soichi

    2011-01-01

    A low-cost light-emitting diode (LED) UV source has been developed for facilitating macromolecular sample centring in the X-ray beam. A direct outcome of the exponential growth of macromolecular crystallography is the continuously increasing demand for synchrotron beam time, both from academic and industrial users. As more and more projects entail screening a profusion of sample crystals, fully automated procedures at every level of the experiments are being implemented at all synchrotron facilities. One of the major obstacles to achieving such automation lies in the sample recognition and centring in the X-ray beam. The capacity of UV light to specifically react with aromatic residues present in proteins or with DNA base pairs is at the basis of UV-assisted crystal centring. Although very efficient, a well known side effect of illuminating biological samples with strong UV sources is the damage induced on the irradiated samples. In the present study the effectiveness of a softer UV light for crystal centring by taking advantage of low-power light-emitting diode (LED) sources has been investigated. The use of UV LEDs represents a low-cost solution for crystal centring with high specificity

  6. Microstructure and structural phase transitions in iron-based superconductors

    International Nuclear Information System (INIS)

    Wang Zhen; Cai Yao; Yang Huai-Xin; Tian Huan-Fang; Wang Zhi-Wei; Ma Chao; Chen Zhen; Li Jian-Qi

    2013-01-01

    Crystal structures and microstructural features, such as structural phase transitions, defect structures, and chemical and structural inhomogeneities, are known to have profound effects on the physical properties of superconducting materials. Recently, many studies on the structural properties of Fe-based high-T c superconductors have been published. This review article will mainly focus on the typical microstructural features in samples that have been well characterized by physical measurements. (i) Certain common structural features are discussed, in particular, the crystal structural features for different superconducting families, the local structural distortions in the Fe 2 Pn 2 (Pn = P As, Sb) or Fe 2 Ch 2 (Ch = S, Se, Te) blocks, and the structural transformations in the 122 system. (ii) In FeTe(Se) (11 family), the superconductivity, chemical and structural inhomogeneities are investigated and discussed in correlation with superconductivity. (iii) In the K 0.8 Fe 1.6+x Se 2 system, we focus on the typical compounds with emphasis on the Fe-vacancy order and phase separations. The microstructural features in other superconducting materials are also briefly discussed. (topical review - iron-based high temperature superconductors)

  7. Competing in the Global LED Industry: The Case of Taiwan

    Directory of Open Access Journals (Sweden)

    Yu-Shan Su

    2014-01-01

    Full Text Available Light-emitting diode (LED is a very essential application for energy-savings nowadays. The revenue of the Taiwan LED components industry is ranked top one in the world, followed by that of Japan and South Korea. Based on the advantage of their electronics industry, Taiwanese LED companies create a unique model to compete with the international firms. Large international LED companies achieve economies of scale by vertically integrating their operations. Taiwanese LED companies specialize and achieve an optimal efficiency by vertically disintegrating across the upstream, midstream, and downstream sectors in the value chains. Taiwanese LED companies create economies of scale and economies of scope through a complete industrial value chain.

  8. Monte carlo analysis of multicolour LED light engine

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Jepsen, Jørgen

    2015-01-01

    A new Monte Carlo simulation as a tool for analysing colour feedback systems is presented here to analyse the colour uncertainties and achievable stability in a multicolour dynamic LED system. The Monte Carlo analysis presented here is based on an experimental investigation of a multicolour LED...

  9. Assessment of community led total sanitation uptake in rural Kenya ...

    African Journals Online (AJOL)

    Background: Community Led Total Sanitation (CLTS) is an innovative community led drive to set up pit latrines in rural Kenya with an aim of promoting sustainable sanitation through behaviour change. It's a behaviour change approach based on social capital that triggers households to build pit latrines without subsidy.

  10. Luminous flux and colour maintenance investigation of integrated LED lamps

    DEFF Research Database (Denmark)

    Corell, Dennis Dan; Thorseth, Anders; Dam-Hansen, Carsten

    2014-01-01

    This article will present an investigation of the luminous flux and colour maintenance of white LED based retrofit lamps. The study includes 23 different types of integrated LED lamps, covering 18 directional and 5 non-directional. Luminous flux and colour data for operation up to 20000 h has been...

  11. Protein structure prediction provides comparable performance to crystallographic structures in docking-based virtual screening.

    Science.gov (United States)

    Du, Hongying; Brender, Jeffrey R; Zhang, Jian; Zhang, Yang

    2015-01-01

    Structure based virtual screening has largely been limited to protein targets for which either an experimental structure is available or a strongly homologous template exists so that a high-resolution model can be constructed. The performance of state of the art protein structure predictions in virtual screening in systems where only weakly homologous templates are available is largely untested. Using the challenging DUD database of structural decoys, we show here that even using templates with only weak sequence homology (identity) structural models can be constructed by I-TASSER which achieve comparable enrichment rates to using the experimental bound crystal structure in the majority of the cases studied. For 65% of the targets, the I-TASSER models, which are constructed essentially in the apo conformations, reached 70% of the virtual screening performance of using the holo-crystal structures. A correlation was observed between the success of I-TASSER in modeling the global fold and local structures in the binding pockets of the proteins versus the relative success in virtual screening. The virtual screening performance can be further improved by the recognition of chemical features of the ligand compounds. These results suggest that the combination of structure-based docking and advanced protein structure modeling methods should be a valuable approach to the large-scale drug screening and discovery studies, especially for the proteins lacking crystallographic structures. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Current NMR Techniques for Structure-Based Drug Discovery.

    Science.gov (United States)

    Sugiki, Toshihiko; Furuita, Kyoko; Fujiwara, Toshimichi; Kojima, Chojiro

    2018-01-12

    A variety of nuclear magnetic resonance (NMR) applications have been developed for structure-based drug discovery (SBDD). NMR provides many advantages over other methods, such as the ability to directly observe chemical compounds and target biomolecules, and to be used for ligand-based and protein-based approaches. NMR can also provide important information about the interactions in a protein-ligand complex, such as structure, dynamics, and affinity, even when the interaction is too weak to be detected by ELISA or fluorescence resonance energy transfer (FRET)-based high-throughput screening (HTS) or to be crystalized. In this study, we reviewed current NMR techniques. We focused on recent progress in NMR measurement and sample preparation techniques that have expanded the potential of NMR-based SBDD, such as fluorine NMR ( 19 F-NMR) screening, structure modeling of weak complexes, and site-specific isotope labeling of challenging targets.

  13. Neighboring Structure Visualization on a Grid-based Layout.

    Science.gov (United States)

    Marcou, G; Horvath, D; Varnek, A

    2017-10-01

    Here, we describe an algorithm to visualize chemical structures on a grid-based layout in such a way that similar structures are neighboring. It is based on structure reordering with the help of the Hilbert Schmidt Independence Criterion, representing an empirical estimate of the Hilbert-Schmidt norm of the cross-covariance operator. The method can be applied to any layout of bi- or three-dimensional shape. The approach is demonstrated on a set of dopamine D5 ligands visualized on squared, disk and spherical layouts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Structure of 2,4-Diaminopyrimidine - Theobromine Alternate Base Pairs

    Science.gov (United States)

    Gengeliczki, Zsolt; Callahan, Michael P.; Kabelac, Martin; Rijs, Anouk M.; deVries, Mattanjah S.

    2011-01-01

    We report the structure of clusters of 2,4-diaminopyrimidine with 3,7-dimethylxanthine (theobromine) in the gas phase determined by IR-UV double resonance spectroscopy in both the near-IR and mid-IR regions in combination with ab initio computations. These clusters represent potential alternate nucleobase pairs, geometrically equivalent to guanine-cytosine. We have found the four lowest energy structures, which include the Watson-Crick base pairing motif. This Watson-Crick structure has not been observed by resonant two-photon ionization (R2PI) in the gas phase for the canonical DNA base pairs.

  15. Data base on avian mortality on man-made structures

    Energy Technology Data Exchange (ETDEWEB)

    Dailey, N. S.

    1978-01-01

    A computerized data base concerning avian mortality on man-made structures is available for searching at the Ecological Sciences Information Center of the Information Center Complex, Information Division, Oak Ridge National Laboratory. This data base, which contains entries from the available literature, provides information on avian mortality from either collision into or electrocution on man-made structures. Primary emphasis has been placed on avian collision with obstacles such as television and radio towers, airport ceilometers, transmission lines, and cooling towers. Other structures included in the studies are fences, glass walls and windows, lighthouses, telegraph and telephone wires, buildings, monuments, smokestacks, and water towers.

  16. Reliability-Based Structural Optimization of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten; Sørensen, John Dalsgaard

    2014-01-01

    More and more wave energy converter (WEC) concepts are reaching prototype level. Once the prototype level is reached, the next step in order to further decrease the levelized cost of energy (LCOE) is optimizing the overall system with a focus on structural and maintenance (inspection) costs...... objectives and will be located at different locations, as well as receive various subsidies. These points should be accounted for when performing structural optimizations of WECs. An illustrative example on the gravity-based foundation of the Wavestar device is performed showing how structural design can...... be optimized taking target reliability levels and different structural failure modes due to extreme loads into account....

  17. A School-Based, Peer-Led, Social Marketing Intervention To Engage Spanish Adolescents in a Healthy Lifestyle ("We Are Cool"-Som la Pera Study): A Parallel-Cluster Randomized Controlled Study.

    Science.gov (United States)

    Aceves-Martins, Magaly; Llauradó, Elisabet; Tarro, Lucia; Moriña, David; Papell-Garcia, Ignasi; Prades-Tena, Jordi; Kettner-Høeberg, Helle; Puiggròs, Francesc; Arola, Lluís; Davies, Amy; Giralt, Montse; Solà, Rosa

    2017-08-01

    Encouraging adolescents to adopt healthy lifestyles can be challenging. The aim of the "Som la Pera" study was to engage adolescents by applying new strategies to increase both their fruit and vegetable consumption and their physical activity (PA) while reducing their sedentary behavior. In disadvantaged neighborhoods of Reus (Spain), two high schools were randomly assigned to the intervention (n = 170 adolescents 13- to 16-year-olds) and two were assigned to the control group (n = 223 adolescents 13- to 16-year-olds). The intervention, which lasted 12 months and spanned 2 academic years (2013-2015), used social marketing (SM) to improve healthy choices. The peer-led strategy involved 5 adolescents who designed and implemented 10 activities as challenges for their 165 school-aged peers. The control group received no intervention. To assess self-reported lifestyles in both groups, the Health Behavior in School-Aged Children Survey was used at baseline and end of study. After 12 months, intervention adolescents showed an increase of 28.9% in ≥1 fruit/day (p < 0.01) and of 18.5% in ≥6 hours/week of PA (p < 0.01) compared with controls. Additionally, intervention group males had an increase of 28.8% in ≥1 vegetable/day (p < 0.01) and of 15.6% in ≤2 hours/day of sedentary activity (p = 0.01) compared with controls. A school-based, peer-led, SM intervention developed by adolescents attending high schools in low-income neighborhoods effectively improved the healthy choices of their school-aged peers, leading to increased fruit consumption and PA in adolescents of both genders. Furthermore, adolescent males were more sensitive to improvements in healthy choices, showing increased vegetable consumption and decreased sedentary behavior.

  18. Double-Exposure Optical Sectioning Structured Illumination Microscopy Based on Hilbert Transform Reconstruction

    Science.gov (United States)

    Zhou, Xing; Lei, Ming; Dan, Dan; Yao, Baoli; Qian, Jia; Yan, Shaohui; Yang, Yanlong; Min, Junwei; Peng, Tong; Ye, Tong; Chen, Guangde

    2015-01-01

    Structured illumination microscopy (SIM) with axially optical sectioning capability has found widespread applications in three-dimensional live cell imaging in recent years, since it combines high sensitivity, short image acquisition time, and high spatial resolution. To obtain one sectioned slice, three raw images with a fixed phase-shift, normally 2π/3, are generally required. In this paper, we report a data processing algorithm based on the one-dimensional Hilbert transform, which needs only two raw images with arbitrary phase-shift for each single slice. The proposed algorithm is different from the previous two-dimensional Hilbert spiral transform algorithm in theory. The presented algorithm has the advantages of simpler data processing procedure, faster computation speed and better reconstructed image quality. The validity of the scheme is verified by imaging biological samples in our developed DMD-based LED-illumination SIM system. PMID:25799234

  19. Buurtzorg: nurse-led community care.

    Science.gov (United States)

    Monsen, Karen A; de Blok, Jos

    2013-01-01

    Buurtzorg is a nurse-led, nurse-run organization of self-managed teams that provide home care to patients in their neighborhoods. Championing humanity over bureaucracy, autonomous teams work with primary care providers, community supports, and family resources to bring patients to optimal functioning as quickly as possible. The award-winning organization grew out of a common sense approach based on principles of trust, autonomy, creativity, simplicity, and collaboration. These organizational principles translate into highly effective and efficient care, satisfied patients, and enthusiastic nurses. The model is being replicated worldwide, with teams starting in Minnesota, Sweden, Japan, and other countries.

  20. Development of Local-Economic-Development Small and Medium Industries (Led-Sme In East Java

    Directory of Open Access Journals (Sweden)

    Rachmad Hidayat

    2013-04-01

    Full Text Available This paper presents the effects of Indonesian government’s developmental efforts of assistance and training performed  on the growth of LED-SME business units and business performance. Both parameters of the government’s assistance and training were used to analyze the impact to the  growth and performance of business unit. To achieve a comprehensive result, samples acquired in this research were about 190 entrepreneurs and managers of LED-SME from East Java. Based on the parameters above, there are five hypotheses made to prove the relationship of the assistance and training to the growth and performance of business units. The structural equation modeling (SEM was carried out to test the hypotheses. The results have shown that the government’s developmental efforts through both assistance and training for the LED-SME were capable on increasing growth and performance of business units. On the other hand, government’s developmental efforts through only trainings were incapable of directly affecting growth of LED-SME business units and performance. To improve the business unit and performance, the government needs to implement developmental principles of LED-SME with the basis of utilizing local natural resources and also the communities of LED-SME as main suppliers for their local markets. In addition, preservation and development of local cultural and traditional arts also need to be the government’s main concern. 

  1. Auger coefficient in GaInN-based laser structures

    Energy Technology Data Exchange (ETDEWEB)

    Draeger, Alexander Daniel; Netzel, Carsten; Brendel, Moritz; Joenen, Holger; Rossow, Uwe; Hangleiter, Andreas [Institut fuer Angewandte Physik, TU Braunschweig (Germany)

    2010-07-01

    Todays GaInN-based light emitting devices such as LEDs and laser diodes show excellent properties in terms of quantum efficiency or threshold current in the violet-blue spectral region. With increasing wavelength towards the green this performance decreases strongly. In particular at longer wavelengths, the quantum efficiency decreases for higher current densities, called the efficiency droop. This phenomenon is still subject to intensive research and different mechanisms such as Auger recombination, losses due to dislocations and carrier escape have been named as possible explanations. We combine optical gain measurements using the variable stripe length technique with model calculations of the optical gain spectra to derive the carrier lifetime. From the dependence of the inverse effective lifetime on carrier density we determine the recombination coefficients for radiative, nonradiative and Auger recombination. The Auger coefficients we obtained are about 1-2 x 10{sup -31} cm{sup 6}/s for GaInN quantum wells with 2.5eVLED droop. Nevertheless, Auger recombination seems to contribute to laser threshold.

  2. Gradient-based optimization in nonlinear structural dynamics

    DEFF Research Database (Denmark)

    Dou, Suguang

    , frequency stabilization, and disk resonator gyroscope. For advanced design of these structures, it is of considerable value to extend current optimization in linear structural dynamics into nonlinear structural dynamics. In this thesis, we present a framework for modelling, analysis, characterization......The intrinsic nonlinearity of mechanical structures can give rise to rich nonlinear dynamics. Recently, nonlinear dynamics of micro-mechanical structures have contributed to developing new Micro-Electro-Mechanical Systems (MEMS), for example, atomic force microscope, passive frequency divider...... coefficients are calculated directly from a nonlinear finite element model. Based on the analysis and the characterization, a new class of optimization problems is studied. In the optimization, design sensitivity analysis is performed by using the adjoint method which is suitable for large-scale structural...

  3. LEDs light up the world

    Energy Technology Data Exchange (ETDEWEB)

    Mather, N.

    2004-06-30

    A lighting system using light-emitting diodes, and privately financed by a Canadian engineering professor at the University of Calgary, has been set up in a village in Nepal in 2000. Since then, through the efforts of the 'Light Up The World' Foundation, established by Dr. Irvine-Halliday, projects have lit up thousands of homes in the Philippines, India, Afghanistan, the Galapagos Islands, Mexico, Sri Lanka, and Angola. Although the goal of the project is primarily to provide lighting for reading and writing for school-children, the project has been the source of many other advantages; creation of enterprise, increased employment, enhanced income, gender equality, and improvements in health and safety among them. Since LED lamps in most cases replace kerosene lamps, the system also has significant environmental benefits. The system as originally envisioned creates electricity by pedal-powered generator, or by solar panels connected to a battery, depending on what is available at each home. Each home is connected to the power supply and supplied with low-energy diode lamps. The lights are extremely efficient and many homes can be equipped with them using less energy than it takes to power a single 100-watt light bulb. 5 photos.

  4. The discovery and structure-activity relationships of pyrano[3,4-b]indole based inhibitors of hepatitis C virus NS5B polymerase.

    Science.gov (United States)

    LaPorte, Matthew G; Draper, Tandy L; Miller, Lori E; Blackledge, Charles W; Leister, Lara K; Amparo, Eugene; Hussey, Alison R; Young, Dorothy C; Chunduru, Srinivas K; Benetatos, Christopher A; Rhodes, Gerry; Gopalsamy, Ariamala; Herbertz, Torsten; Burns, Christopher J; Condon, Stephen M

    2010-05-01

    We describe the structure-activity relationship of the C1-group of pyrano[3,4-b]indole based inhibitors of HCV NS5B polymerase. Further exploration of the allosteric binding site led to the discovery of the significantly more potent compound 12. 2010 Elsevier Ltd. All rights reserved.

  5. Effect of high current density to defect generation of blue LED and its characterization with transmission electron microscope

    Science.gov (United States)

    Gunawan, R.; Sugiarti, E.; Isnaeni; Purawiardi, R. I.; Widodo, H.; Muslimin, A. N.; Yuliasari; Ronaldus, C. E.; Prastomo, N.; Hastuty, S.

    2018-03-01

    The optical, electrical and structural characteristics of InGaN-based blue light-emitting diodes (LEDs) were investigated to identify the degradation of LED before and after current injection. The sample was injected by high current of 200 A/cm2 for 5 and 20 minutes. It was observed that injection of current shifts light intensity and wavelength characteristics that indicated defect generation. Transmission Electron Microscopy (TEM) characterization was carried out in order to clarify the structure degradation caused by defect in active layer which consisted of 14 quantum well with thickness of about 5 nm and confined with barrier layer with thickness of about 12 nm. TEM results showed pre-existing defect in LED before injection with high current. Furthermore, discontinue and edge defect was found in dark spot region of LED after injection with high current.

  6. General enumeration of RNA secondary structures based on new ...

    African Journals Online (AJOL)

    Crick base pairs between AU and GC. Based on the new representation, this paper also computes the number of various types of constrained secondary structures taking the minimum stack length 1 and minimum size m for each bonding loop as ...

  7. Towards Computerized Adaptive Assessment Based on Structured Tasks

    NARCIS (Netherlands)

    Tvarožek, Jozef; Kravcik, Milos; Bieliková, Mária

    2008-01-01

    Tvarožek, J., Kravčík, M., & Bieliková, M. (2008). Towards Computerized Adaptive Assessment Based on Structured Tasks. In W. Nejdl et al. (Eds.), Adaptive Hypermedia and Adaptive Web-Based Systems (pp. 224-234). Springer Berlin / Heidelberg.

  8. Structural analysis of the central Columbia Plateau utilizing radar, digital topography, and magnetic data bases

    International Nuclear Information System (INIS)

    Thiessen, R.L.; Eliason, J.R.; Johnson, L.K.; Brougher, C.W.

    1991-08-01

    Interest in the Hanford site (Washington) as a nuclear production, power, and waste disposal site has led to generation of a vast quantity of geophysical and remote sensing data sets of the central Columbia Plateau. To data, these various studies, including at least 13 independent magnetic linear and image lineament studies, have not been adequately correlated. Therefore, these studies provide a unique opportunity to compare and contrast the viability of the different geophysical and remote sensing techniques. The geology of the central Columbia Plateau is characterized by subdued topography and limited outcrop, with most of the exposure concentrated in localized folded/faulted mountains (the Yakima folds) and along river canyons. In order to efficiently compare lineament data bases, we have written an automated computer routine that correlated lineaments that are within a user specified distance of each other. The angle between their trends has to be less than an input maximum separation angle. If more than two lineament maps exist for the area, the analyst may also specify the minimum number of times each structure must be seen. The lineament correlation routine was applied to data bases of all aeromagnetic linears as well as lineaments seen on radar and a digital elevation model DEM image. Geologic structures align with a set of three-dimensional planar structures identified with our Geologic Spatial Analysis (GSA) system. The GSA analysis is based upon computer automated detection of valley bottoms as defined by a DEM

  9. Structure-based classification and ontology in chemistry

    Directory of Open Access Journals (Sweden)

    Hastings Janna

    2012-04-01

    Full Text Available Abstract Background Recent years have seen an explosion in the availability of data in the chemistry domain. With this information explosion, however, retrieving relevant results from the available information, and organising those results, become even harder problems. Computational processing is essential to filter and organise the available resources so as to better facilitate the work of scientists. Ontologies encode expert domain knowledge in a hierarchically organised machine-processable format. One such ontology for the chemical domain is ChEBI. ChEBI provides a classification of chemicals based on their structural features and a role or activity-based classification. An example of a structure-based class is 'pentacyclic compound' (compounds containing five-ring structures, while an example of a role-based class is 'analgesic', since many different chemicals can act as analgesics without sharing structural features. Structure-based classification in chemistry exploits elegant regularities and symmetries in the underlying chemical domain. As yet, there has been neither a systematic analysis of the types of structural classification in use in chemistry nor a comparison to the capabilities of available technologies. Results We analyze the different categories of structural classes in chemistry, presenting a list of patterns for features found in class definitions. We compare these patterns of class definition to tools which allow for automation of hierarchy construction within cheminformatics and within logic-based ontology technology, going into detail in the latter case with respect to the expressive capabilities of the Web Ontology Language and recent extensions for modelling structured objects. Finally we discuss the relationships and interactions between cheminformatics approaches and logic-based approaches. Conclusion Systems that perform intelligent reasoning tasks on chemistry data require a diverse set of underlying computational

  10. Structure-based druggability assessment of the mammalian structural proteome with inclusion of light protein flexibility.

    Directory of Open Access Journals (Sweden)

    Kathryn A Loving

    2014-07-01

    Full Text Available Advances reported over the last few years and the increasing availability of protein crystal structure data have greatly improved structure-based druggability approaches. However, in practice, nearly all druggability estimation methods are applied to protein crystal structures as rigid proteins, with protein flexibility often not directly addressed. The inclusion of protein flexibility is important in correctly identifying the druggability of pockets that would be missed by methods based solely on the rigid crystal structure. These include cryptic pockets and flexible pockets often found at protein-protein interaction interfaces. Here, we apply an approach that uses protein modeling in concert with druggability estimation to account for light protein backbone movement and protein side-chain flexibility in protein binding sites. We assess the advantages and limitations of this approach on widely-used protein druggability sets. Applying the approach to all mammalian protein crystal structures in the PDB results in identification of 69 proteins with potential druggable cryptic pockets.

  11. Performance based investigations of structural systems under fire

    DEFF Research Database (Denmark)

    Gentili, Filippo; Crosti, Chiara; Giuliani, Luisa

    2010-01-01

    Prescriptive measures and procedures developed over the past here are mostly aimed at preventing structural failures of single elements for the time required for the evacuation. The response to fire and fire effects of the structural system as a whole remains often unknown and the survival of the...... structures are presented and discussed, with particular attention to methodological aspects. The effects of different assumptions in the modeling and in the definition of the collapse are highlighted, as critical aspects of a performance-based investigation....... these kinds of events, the mitigation of possible collapse induced by fire should be achieved. In this respect, a performance-based investigation of the structure aimed at highlight fire effects and fire-induced collapse mechanisms becomes of interest. In the paper collapse mechanisms of some simple...

  12. Self-assembly of boron-based supramolecular structures

    OpenAIRE

    Christinat, Nicolas

    2008-01-01

    This work describes the synthesis and characterization of boronic acid-based supramolecular structures. Macrocycles, dendritic structures, polymers, rotaxanes, and cages were assembled using four types of reversible reactions. The key point of the strategy is the parallel utilization of two –or more– of these reactions. Initially, aryl and alkylboronic acids were condensed with dihydroxypyridine ligands to give tetrameric or pentameric macrocycles, in which four or five boronate esters are co...

  13. Structure-Based Simulations Reveal Concerted Dynamics of GPCR Activation

    OpenAIRE

    Leioatts, Nicholas; Suresh, Pooja; Romo, Tod D.; Grossfield, Alan

    2014-01-01

    G protein-coupled receptors (GPCRs) are a vital class of proteins that transduce biological signals across the cell membrane. However, their allosteric activation mechanism is not fully understood; crystal structures of active and inactive receptors have been reported, but the functional pathway between these two states remains elusive. Here, we employ structure-based (Gō-like) models to simulate activation of two GPCRs, rhodopsin and the β2 adrenergic receptor (β2AR). We used data-derived re...

  14. Excellent color rendering indexes of multi-package white LEDs.

    Science.gov (United States)

    Oh, Ji Hye; Yang, Su Ji; Sung, Yeon-Goog; Do, Y R

    2012-08-27

    This study introduces multi-package white light-emitting diodes (LEDs) system with the ability to realize high luminous efficacy and an excellent color rendering index (CRI, R a) using the R B,M A B,M G B,M C B (R B,M A B,M G B,M denoted as a long-pass dichroic filter (LPDF)-capped, monochromatic red, amber and green phosphor converted-LED (pc-LED) pumped by a blue LED chip, and C B denoted as a cyan and blue mixed pc-LED pumped by a blue LED) system. The luminous efficacy and color rendering index (CRI) of multi-package white LED systems are compared while changing the concentration of the cyan phosphor used in the paste of a cyan-blue LED package and the driving current of individual LEDs in multi-package white LEDs at correlated color temperatures (CCTs) ranging from 6,500 K (cold white) to 2,700 K (warm white) using a set of eight CCTs as specified by the American National Standards Institute (ANSI) standard number C78.377-2008. A R B,M A B,M G B,M C B white LED system provides high luminous efficacy (≥ 96 lm/W) and a color rendering index (≥ 91) encompassing the complete CCT range. We also compare the optical properties of the R B,M A B,M G B,M C B system with those of the R B,M A B,M G B,M B and RAGB (red, amber, green, and blue semiconductor-type narrow-spectrum-band LEDs) systems. It can be expected that the cyan color added to a blue LED in multi-package white LEDs based on LPDF-capped, phosphor-converted monochromatic LEDs will meet the needs of the high-quality, highly efficient, full-color white LED lighting market in the near future.

  15. Smartphone based hemispherical photography for canopy structure measurement

    Science.gov (United States)

    Wan, Xuefen; Cui, Jian; Jiang, Xueqin; Zhang, Jingwen; Yang, Yi; Zheng, Tao

    2018-01-01

    The canopy is the most direct and active interface layer of the interaction between plant and environment, and has important influence on energy exchange, biodiversity, ecosystem matter and climate change. The measurement about canopy structure of plant is an important foundation to analyze the pattern, process and operation mechanism of forest ecosystem. Through the study of canopy structure of plant, solar radiation, ambient wind speed, air temperature and humidity, soil evaporation, soil temperature and other forest environmental climate characteristics can be evaluated. Because of its accuracy and effectiveness, canopy structure measurement based on hemispherical photography has been widely studied. However, the traditional method of canopy structure hemispherical photogrammetry based on SLR camera and fisheye lens. This method is expensive and difficult to be used in some low-cost occasions. In recent years, smartphone technology has been developing rapidly. The smartphone not only has excellent image acquisition ability, but also has the considerable computational processing ability. In addition, the gyroscope and positioning function on the smartphone will also help to measure the structure of the canopy. In this paper, we present a smartphone based hemispherical photography system. The system consists of smart phones, low-cost fisheye lenses and PMMA adapters. We designed an Android based App to obtain the canopy hemisphere images through low-cost fisheye lenses and provide horizontal collimation information. In addition, the App will add the acquisition location tag obtained by GPS and auxiliary positioning method in hemisphere image information after the canopy structure hemisphere image acquisition. The system was tested in the urban forest after it was completed. The test results show that the smartphone based hemispherical photography system can effectively collect the high-resolution canopy structure image of the plant.

  16. Hard and soft acids and bases: structure and process.

    Science.gov (United States)

    Reed, James L

    2012-07-05

    Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.

  17. Assessment of Performance-based Requirements for Structural Design

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    2005-01-01

    The paper presents how actions can be assessed for a performance-based structural fire safety design from the first formulations in the building program to the final derivations of the fire load to be applied for each structural member. In order to indicate what is of importance for the assessment...... of the requirements, a couple of simple analyses of structural response are made. The examples are chosen deliberately to show the difference between a traditional design based on standard fire resistance and a performance-based approach. A methodology is developed for a decision on the safety level...... and for a detailed assessment of the requirements. The design requirements to be used for a factory producing elements for industrial housing for unknown costumers are discussed, and a fully developed fire is recommended as a common requirement for domestic houses, hotels, offices, schools and hospitals. In addition...

  18. A Tensor-Based Structural Damage Identification and Severity Assessment

    Science.gov (United States)

    Anaissi, Ali; Makki Alamdari, Mehrisadat; Rakotoarivelo, Thierry; Khoa, Nguyen Lu Dang

    2018-01-01

    Early damage detection is critical for a large set of global ageing infrastructure. Structural Health Monitoring systems provide a sensor-based quantitative and objective approach to continuously monitor these structures, as opposed to traditional engineering visual inspection. Analysing these sensed data is one of the major Structural Health Monitoring (SHM) challenges. This paper presents a novel algorithm to detect and assess damage in structures such as bridges. This method applies tensor analysis for data fusion and feature extraction, and further uses one-class support vector machine on this feature to detect anomalies, i.e., structural damage. To evaluate this approach, we collected acceleration data from a sensor-based SHM system, which we deployed on a real bridge and on a laboratory specimen. The results show that our tensor method outperforms a state-of-the-art approach using the wavelet energy spectrum of the measured data. In the specimen case, our approach succeeded in detecting 92.5% of induced damage cases, as opposed to 61.1% for the wavelet-based approach. While our method was applied to bridges, its algorithm and computation can be used on other structures or sensor-data analysis problems, which involve large series of correlated data from multiple sensors. PMID:29301314

  19. Synthesis, Crystal Structure, and Luminescence Properties of Tunable Red-Emitting Nitride Solid Solutions (Ca1-xSrx)16Si17N34:Eu2+for White LEDs.

    Science.gov (United States)

    Chen, Hang; Ding, Jianyan; Ding, Xin; Wang, Xicheng; Cao, Yaxin; Zhao, Zhengyan; Wang, Yuhua

    2017-09-18

    A series of nitride solid solutions (Ca 1-x Sr x ) 16 Si 17 N 34 :0.03Eu 2+ were successfully synthesized through the conventional solid-state method. The electronic crystal structure and photoluminescence characteristics were studied in detail. The excitation in the near-ultraviolet and blue regions of the samples shows a broad band in the 250-550 nm range, which can match well with the n-UV and blue lighting-emitting diode chips. Partial substitution of Ca 2+ by Sr 2+ results in a redshift emission, and the impacts of Sr content on the luminescence were researched in detail. Under 410 nm excitation, the phosphor exhibited tunable red emission from 616 to 653 nm by changing the concentration of Sr 2+ . Based on the crystal data, the emission can be fitted into three distinguished Gaussian components, which are attributed to the different Eu 2+ luminescence centers occupied in three disparate Ca 2+ (Sr 2+ ) lattice sites. The temperature quenching property of the phosphor was also investigated, and the good thermal stability of the phosphors was analyzed through the activation energy for thermal quenching. And the obtained CCT values from 2642 to 2817 K are suitable for a warm white light region. All the results indicated that the phosphors have possible application in the warm white light-emitting diodes.

  20. Optical-based smart structures for tamper-indicating applications

    International Nuclear Information System (INIS)

    Sliva, P.; Anheier, N.C.; Simmons, K.L.; Undem, H.A.

    1996-11-01

    This report is a compilation of several related projects performed from 1991 through 1996 concerning the design, construction, and application of optical-based smart structure to tamper-indicating and sensing secure containers. Due to several influences, the projects were carried through to varying degrees of completion. Cancellation of the overall project at the client level motivated the authors to gather all of the technology and ideas about smart structures developed during these several projects, whether completed or just conceptualized, into one document. Although each section individually discusses a specific project, the overall document is written chronologically with each successive section showing how increased smart structure complexity was integrated into the container

  1. Hybrid structures based on quantum dots and graphene nanobelts

    Science.gov (United States)

    Reznik, I. A.; Gromova, Yu. A.; Zlatov, A. S.; Baranov, M. A.; Orlova, A. O.; Moshkalev, S. A.; Maslov, V. G.; Baranov, A. V.; Fedorov, A. V.

    2017-01-01

    Luminescence and photoelectric properties of hybrid structures based on CdSe/ZnS quantum dots (QDs) and multilayer graphene have been investigated. A correlation between the luminescence quantum yield of QDs and their photoelectric properties in hybrid structures is established. It is shown that a decrease in the QD luminescence quantum yield due to adsorption of 1-(2-pyridylazo)-2-naphtol azo dye molecules onto the QD surface and a photoinduced increase in the QD luminescence quantum yield are accompanied by a symbate change in the hybrid structure photoconductivity.

  2. Tunable reflecting terahertz filter based on chirped metamaterial structure

    Science.gov (United States)

    Yang, Jing; Gong, Cheng; Sun, Lu; Chen, Ping; Lin, Lie; Liu, Weiwei

    2016-01-01

    Tunable reflecting terahertz bandstop filter based on chirped metamaterial structure is demonstrated by numerical simulation. In the metamaterial, the metal bars are concatenated to silicon bars with different lengths. By varying the conductivity of the silicon bars, the reflectivity, central frequency and bandwidth of the metamaterial could be tuned. Light illumination could be introduced to change the conductivity of the silicon bars. Numerical simulations also show that the chirped metamaterial structure is insensitive to the incident angle and polarization-dependent. The proposed chirped metamaterial structure can be operated as a tunable bandstop filter whose modulation depth, bandwidth, shape factor and center frequency can be controlled by light pumping. PMID:27941833

  3. Integrated Reliability-Based Optimal Design of Structures

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1987-01-01

    the reliability decreases with time it is often necessary to design an inspection and repair programme. For example the reliability of offshore steel structures decreases with time due to corrosion and development of fatigue cracks. Until now most inspection and repair strategies are based on experience rather......In conventional optimal design of structural systems the weight or the initial cost of the structure is usually used as objective function. Further, the constraints require that the stresses and/or strains at some critical points have to be less than some given values. Finally, all variables...

  4. Secure data structures based on multi-party computation

    DEFF Research Database (Denmark)

    Toft, Tomas

    2011-01-01

    This work considers data structures based on multi-party computation (MPC) primitives: structuring secret (e.g. secret shared and potentially unknown) data such that it can both be queried and updated efficiently. Implementing an oblivious RAM (ORAM) using MPC allows any existing data structure t...... shown that any information theoretically secure ORAM with n memory locations requires at least log n random bits per read/write to hide the access pattern. In contrast, the present construction achieves security with a completely deterministic access pattern....

  5. Peer-led and professional-led group interventions for people with co-occurring disorders: a qualitative study.

    Science.gov (United States)

    Pallaveshi, Luljeta; Balachandra, Krishna; Subramanian, Priya; Rudnick, Abraham

    2014-05-01

    This pilot study evaluated the experience of people with co-occurring disorders (mental illness and addiction) in relation to peer-led and professional-led group interventions. The study used a qualitative (phenomenological) approach to evaluate the experience of a convenience sample of 6 individuals with co-occurring disorders who participated in up to 8 sessions each of both peer-led and professional-led group interventions (with a similar rate of attendance in both groups). The semi-structured interview data were coded and thematically analyzed. We found 5 themes within and across the 2 interventions. In both groups, participants experienced a positive environment and personal growth, and learned, albeit different things. They were more comfortable in the peer-led group and acquired more knowledge and skills in the professional-led group. Offering both peer-led and professional-led group interventions to people with co-occurring disorders may be better than offering either alone.

  6. Fokusgruppeinterview som led i en evalueringsproces

    DEFF Research Database (Denmark)

    Andersen-Mølgaard, Hanna; Harrit, Ole

    2006-01-01

    Teoretiske begrundelser og perspektiver, responsiv-konstruktivistisk evaluering, fokusgruppeinterview som led i BIKVAmodellen, eksempler, vurdering og perspektivering......Teoretiske begrundelser og perspektiver, responsiv-konstruktivistisk evaluering, fokusgruppeinterview som led i BIKVAmodellen, eksempler, vurdering og perspektivering...

  7. Evaluation of LED vehicular and pedestrian modules.

    Science.gov (United States)

    2009-04-01

    This study was conducted to verify the compliance of vehicular and pedestrian LED traffic signal modules with the Institute : of Transportation Engineers specifications; and to assess drivers preferences of the LED modules. Four vehicular modules ...

  8. LED belichting tijdens het voortrekken van lelie

    NARCIS (Netherlands)

    Kok, B.J.; Wildschut, J.

    2010-01-01

    De laatste jaren staat het gebruik van LED-lampen in de tuinbouw in de belangstelling. Uit vele onderzoeken is al gebleken dat LED-lampen op dit moment nog geen alternatief zijn voor de SON-T lampen. Het grote voordeel van LED-lampen is dat ze monochromatisch licht van alle mogelijke golflengtes

  9. ‘No Blue’ White LED

    DEFF Research Database (Denmark)

    Ou, Haiyan; Corell, Dennis Dan; Dam-Hansen, Carsten

    2010-01-01

    This paper explored the feasibility of making a white LED light source by color mixing method without using the blue color. This ‘no blue’ white LED has potential applications in photolithography room illumination, medical treatment and biophotonics research. A no-blue LED was designed, and the p...

  10. Next generation DNA led technologies

    CERN Document Server

    Jyothsna, G; Kashyap, Amita

    2016-01-01

    This brief highlights advances in DNA technologies and their wider applications. DNA is the source of life and has been studied since a generation, but very little is known as yet. Several sophisticated technologies of the current era have laid their foundations on the principle of DNA based mechanisms. DNA based technologies are bringing a new revolution of Advanced Science and Technology. Forensic Investigation, Medical Diagnosis, Paternity Disputes, Individual Identity, Health insurance, Motor Insurance have incorporated the DNA testing and profiling technologies for settling the issues.

  11. Stochastic collocation-based finite element of structural nonlinear dynamics with application in composite structures

    Directory of Open Access Journals (Sweden)

    Sepahvand K.

    2016-01-01

    Full Text Available Stochastic analysis of structures having nonlinearity by means of sampling methods leads to expensive cost in term of computational time. In contrast, non-sampling methods based on the spectral representation of uncertainty are very efficient with comparable accurate results. In this pa- per, the application of spectral methods to nonlinear dynamics of structures with random parameters is investigated. The impact of the parameter randomness on structural responses has been consid- ered. To this end, uncertain parameters and the structure responses are represented using the gPC expansions with unknown deterministic coefficients and random orthogonal polynomial basis. The deterministic finite element model of the structure is used as black-box and it is executed on a set of random collocation points. As the sample structure responses are estimated, a nonlinear optimization process is employed to calculate the unknown coefficients. The method has this main advantage that can be used for complicated nonlinear structural dynamic problems for which the deterministic FEM model has been already developed. Furthermore, it is very time efficient in comparison with sampling methods, as MC simulations. The application of the method is applied to the nonlinear transient analysis of composite beam structures including uncertain quadratic random damping. The results show that the proposed method can capture the large range of uncertainty in input parameters as well as in structural dynamic responses while it is too time-efficient.

  12. Structure-Based Alignment and Consensus Secondary Structures for Three HIV-Related RNA Genomes.

    Science.gov (United States)

    Lavender, Christopher A; Gorelick, Robert J; Weeks, Kevin M

    2015-05-01

    HIV and related primate lentiviruses possess single-stranded RNA genomes. Multiple regions of these genomes participate in critical steps in the viral replication cycle, and the functions of many RNA elements are dependent on the formation of defined structures. The structures of these elements are still not fully understood, and additional functional elements likely exist that have not been identified. In this work, we compared three full-length HIV-related viral genomes: HIV-1NL4-3, SIVcpz, and SIVmac (the latter two strains are progenitors for all HIV-1 and HIV-2 strains, respectively). Model-free RNA structure comparisons were performed using whole-genome structure information experimentally derived from nucleotide-resolution SHAPE reactivities. Consensus secondary structures were constructed for strongly correlated regions by taking into account both SHAPE probing structural data and nucleotide covariation information from structure-based alignments. In these consensus models, all known functional RNA elements were recapitulated with high accuracy. In addition, we identified multiple previously unannotated structural elements in the HIV-1 genome likely to function in translation, splicing and other replication cycle processes; these are compelling targets for future functional analyses. The structure-informed alignment strategy developed here will be broadly useful for efficient RNA motif discovery.

  13. Teacher led school-based surveillance can allow accurate tracking of emerging infectious diseases - evidence from serial cross-sectional surveys of febrile respiratory illness during the H1N1 2009 influenza pandemic in Singapore

    Directory of Open Access Journals (Sweden)

    Soh Shu E

    2012-12-01

    Full Text Available Abstract Background Schools are important foci of influenza transmission and potential targets for surveillance and interventions. We compared several school-based influenza monitoring systems with clinic-based influenza-like illness (ILI surveillance, and assessed the variation in illness rates between and within schools. Methods During the initial wave of pandemic H1N1 (pdmH1N1 infections from June to Sept 2009 in Singapore, we collected data on nation-wide laboratory confirmed cases (Sch-LCC and daily temperature monitoring (Sch-DTM, and teacher-led febrile respiratory illness reporting in 6 sentinel schools (Sch-FRI. Comparisons were made against age-stratified clinic-based influenza-like illness (ILI data from 23 primary care clinics (GP-ILI and proportions of ILI testing positive for pdmH1N1 (Lab-ILI by computing the fraction of cumulative incidence occurring by epidemiological week 30 (when GP-ILI incidence peaked; and cumulative incidence rates between school-based indicators and sero-epidemiological pdmH1N1 incidence (estimated from changes in prevalence of A/California/7/2009 H1N1 hemagglutination inhibition titers ≥ 40 between pre-epidemic and post-epidemic sera. Variation in Sch-FRI rates in the 6 schools was also investigated through a Bayesian hierarchical model. Results By week 30, for primary and secondary school children respectively, 63% and 79% of incidence for Sch-LCC had occurred, compared with 50% and 52% for GP-ILI data, and 48% and 53% for Sch-FRI. There were 1,187 notified cases and 7,588 episodes in the Sch-LCC and Sch-DTM systems; given school enrollment of 485,723 children, this represented 0.24 cases and 1.6 episodes per 100 children respectively. Mean Sch-FRI rate was 28.8 per 100 children (95% CI: 27.7 to 29.9 in the 6 schools. We estimate from serology that 41.8% (95% CI: 30.2% to 55.9% of primary and 43.2% (95% CI: 28.2% to 60.8% of secondary school-aged children were infected. Sch-FRI rates were similar across

  14. Teacher led school-based surveillance can allow accurate tracking of emerging infectious diseases - evidence from serial cross-sectional surveys of febrile respiratory illness during the H1N1 2009 influenza pandemic in Singapore.

    Science.gov (United States)

    Soh, Shu E; Cook, Alex R; Chen, Mark I C; Lee, Vernon J; Cutter, Jeffery L; Chow, Vincent T K; Tee, Nancy W S; Lin, Raymond T P; Lim, Wei-Yen; Barr, Ian G; Lin, Cui; Phoon, Meng Chee; Ang, Li Wei; Sethi, Sunil K; Chong, Chia Yin; Goh, Lee Gan; Goh, Denise L M; Tambyah, Paul A; Thoon, Koh Cheng; Leo, Yee Sin; Saw, Seang Mei

    2012-12-04

    Schools are important foci of influenza transmission and potential targets for surveillance and interventions. We compared several school-based influenza monitoring systems with clinic-based influenza-like illness (ILI) surveillance, and assessed the variation in illness rates between and within schools. During the initial wave of pandemic H1N1 (pdmH1N1) infections from June to Sept 2009 in Singapore, we collected data on nation-wide laboratory confirmed cases (Sch-LCC) and daily temperature monitoring (Sch-DTM), and teacher-led febrile respiratory illness reporting in 6 sentinel schools (Sch-FRI). Comparisons were made against age-stratified clinic-based influenza-like illness (ILI) data from 23 primary care clinics (GP-ILI) and proportions of ILI testing positive for pdmH1N1 (Lab-ILI) by computing the fraction of cumulative incidence occurring by epidemiological week 30 (when GP-ILI incidence peaked); and cumulative incidence rates between school-based indicators and sero-epidemiological pdmH1N1 incidence (estimated from changes in prevalence of A/California/7/2009 H1N1 hemagglutination inhibition titers ≥ 40 between pre-epidemic and post-epidemic sera). Variation in Sch-FRI rates in the 6 schools was also investigated through a Bayesian hierarchical model. By week 30, for primary and secondary school children respectively, 63% and 79% of incidence for Sch-LCC had occurred, compared with 50% and 52% for GP-ILI data, and 48% and 53% for Sch-FRI. There were 1,187 notified cases and 7,588 episodes in the Sch-LCC and Sch-DTM systems; given school enrollment of 485,723 children, this represented 0.24 cases and 1.6 episodes per 100 children respectively. Mean Sch-FRI rate was 28.8 per 100 children (95% CI: 27.7 to 29.9) in the 6 schools. We estimate from serology that 41.8% (95% CI: 30.2% to 55.9%) of primary and 43.2% (95% CI: 28.2% to 60.8%) of secondary school-aged children were infected. Sch-FRI rates were similar across the 6 schools (23 to 34 episodes per 100

  15. UV LED lighting for automated crystal centring.

    Science.gov (United States)

    Chavas, Leonard M G; Yamada, Yusuke; Hiraki, Masahiko; Igarashi, Noriyuki; Matsugaki, Naohiro; Wakatsuki, Soichi

    2011-01-01

    A direct outcome of the exponential growth of macromolecular crystallography is the continuously increasing demand for synchrotron beam time, both from academic and industrial users. As more and more projects entail screening a profusion of sample crystals, fully automated procedures at every level of the experiments are being implemented at all synchrotron facilities. One of the major obstacles to achieving such automation lies in the sample recognition and centring in the X-ray beam. The capacity of UV light to specifically react with aromatic residues present in proteins or with DNA base pairs is at the basis of UV-assisted crystal centring. Although very efficient, a well known side effect of illuminating biological samples with strong UV sources is the damage induced on the irradiated samples. In the present study the effectiveness of a softer UV light for crystal centring by taking advantage of low-power light-emitting diode (LED) sources has been investigated. The use of UV LEDs represents a low-cost solution for crystal centring with high specificity.

  16. Tunable, omnidirectional structural color on reflection based on metal-SiOx-metal structure

    Science.gov (United States)

    Yang, Chenying; Mao, Kening; Shen, Weidong; Fang, Bo; Fang, Xu; Zhang, Xing; Zhang, Yueguang; Liu, Xu

    2016-12-01

    An omnidirectional structural color based on the metal-SiOx-metal stack structure is proposed, which can present the same perceived color for a broad range of incidence angles. The tunable structural color can be obtained with adjustable intermediate dielectric layer by simply adjusting the deposition condition, especially the oxygen flow rate during the deposition processes. The resonance condition can be satisfied across the whole visible light region with this special dielectric. The strong absorption caused by the resonance within the metal-SiOx-metal structure accounts for the efficient spectral filtering feature, and the constant phase shift within the dielectric layer leads to angle insensitivity of this color filter. This simple color tuning method for omnidirectional structural colors can have a great potential in various applications such as displaying, imaging, colorful decoration, anti-counterfeiting and so forth.

  17. Strain Concentration at Structural Discontinuities and Its Prediction Based on Characteristics of Compliance Change in Structures

    Science.gov (United States)

    Kasahara, Naoto

    Elevated temperature structural design codes pay attention to strain concentration at structural discontinuities due to creep and plasticity, since it causes an increase in creep-fatigue damage of materials. One of the difficulties in predicting strain concentration is its dependence on the magnitude of loading, the constitutive equations, and the duration of loading. In this study, the author investigated the fundamental mechanism of strain concentration and its main factors. The results revealed that strain concentration is caused by strain redistribution between elastic and inelastic regions, which can be quantified by the characteristics of structural compliance. The characteristics of structural compliance are controlled by elastic region in structures and are insensitive to constitutive equations. It means that inelastic analysis can be easily applied to obtain compliance characteristics. By utilizing this fact, a simplified inelastic analysis method was proposed based on the characteristics of compliance change for the prediction of strain concentration.

  18. Structural parameter study on polymer-based ultrasonic motor

    Science.gov (United States)

    Wu, Jiang; Mizuno, Yosuke; Nakamura, Kentaro

    2017-11-01

    Our previous study has shown that traveling-wave rotary ultrasonic motors using polymer-based vibrators can work in the same way as conventional motors with metal-based vibrators. It is feasible to enhance the performance, particularly output torques, of polymer-based motors by adjusting several key dimensions of their vibrators. In this study, poly phenylene sulfide, a functional polymer exhibiting low attenuation at ultrasonic frequency, is selected as the vibrating body, which is activated with a piezoelectric ceramic element bonded on its back surface. The optimal thicknesses of the polymer-based motors are higher than those of metal-based motors. When the same voltages were applied, the maximum torques and output powers available with the polymer-based motors were lower than the values of the metal-based motors with the same structures. The reasons for the lower torque were explained on the basis of vibration modes. First, the force factors of the polymer-based vibrators are lower than those of metal-based vibrators owing to the great difference in the mechanical constants between polymers and piezoelectric ceramics. Subsequently, though the force factors of polymer-based vibrators can be slightly enhanced by increasing their thicknesses, the unavoidable radial vibrations become higher and cause undesirable friction loss, which reduces the output torques. Though the polymer-based motors have rotation speeds comparable to those of metal-based motors, their output power are lower due to the low electromechanical coupling factors of the polymer-based vibrators.

  19. Proposed Doctrine Based Structure of the Armored Reconnaissance Squadron

    Science.gov (United States)

    2017-06-09

    the literature reviewed, specifically in professional Canadian Army publications such as the Army Journal and the Armour Bulletin, where one would...expect to find capability based discourse; there is a lack of proposed structure based on capability, task or equipment. The Armour Bulletin serves...Lieutenant Joe and De Silva, Lieutenant Jon. 2014. “RCD Lessons Learned During Exercise MAPLE RESOLVE 1401.” Armour Bulletin: 27-29. Childs, Major Dale

  20. Structural bases of GM1 gangliosidosis and Morquio B disease.

    Science.gov (United States)

    Morita, Mizuki; Saito, Seiji; Ikeda, Kazuyoshi; Ohno, Kazuki; Sugawara, Kanako; Suzuki, Toshihiro; Togawa, Tadayasu; Sakuraba, Hitoshi

    2009-09-01

    Allelic mutations of the lysosomal beta-galactosidase gene cause heterogeneous clinical phenotypes, such as GM1 gangliosidosis and Morquio B disease, the former being further classified into three variants, namely infantile, juvenile and adult forms; and heterogeneous biochemical phenotypes were shown in these forms. We tried to elucidate the bases of these diseases from a structural viewpoint. We first constructed a three-dimensional structural model of human beta-galactosidase by means of homology modeling. The human beta-galactosidase consists of three domains, such as, a TIM barrel fold domain, which functions as a catalytic domain, and two galactose-binding domain-like fold domains. We then constructed structural models of representative mutant beta-galactosidase proteins (G123R, R201C, I51T and Y83H) and predicted the structural change associated with each phenotype by calculating the number of affected atoms, determining the root-mean-square deviation and the solvent-accessible surface area, and by color imaging. The results show that there is a good correlation between the structural changes caused by amino-acid substitutions in the beta-galactosidase molecule, as well as biochemical and clinical phenotypes in these representative cases. Protein structural study is useful for elucidating the bases of these diseases.

  1. Tamper indicating and sensing optical-based smart structures

    International Nuclear Information System (INIS)

    Sliva, P.; Anheier, N.C.; Gordon, N.R.; Simmons, K.L.; Stahl, K.A.; Undem, H.A.

    1995-05-01

    This paper has presented an overview of the type of optical-based structures that can be designed and constructed. These smart structures are capable of responding to their environment. The examples given represent a modest sampling of the complexity that can be achieved in both design and practice. Tamper-indicating containers and smart, sensing windows demonstrate just a few of the applications. We have shown that optical-based smart structures can be made multifunctional with the sensing built in. The next generation smart structure will combine the sensing functionality of these optical-based smart structures with other sensors such as piezoelectrics and electro-rheological fluids to not only be able to respond to the environment, but to adapt to it as well. An example of functionality in this regime would be a piezosensor that senses pressure changes (e.g., shock waves), which then causes an electro-rheological fluid to change viscosity. A fiber sensor located in or near the electro-rheological fluid senses the stiffness change and sends a signal through a feedback loop back to the piezosensor for additional adjustments to the electro-rheological fluid

  2. Classification of the Pospiviroidae based on their structural hallmarks.

    Directory of Open Access Journals (Sweden)

    Tamara Giguère

    Full Text Available The simplest known plant pathogens are the viroids. Because of their non-coding single-stranded circular RNA genome, they depend on both their sequence and their structure for both a successful infection and their replication. In the recent years, important progress in the elucidation of their structures was achieved using an adaptation of the selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE protocol in order to probe viroid structures in solution. Previously, SHAPE has been adapted to elucidate the structures of all of the members of the family Avsunviroidae, as well as those of a few members of the family Pospiviroidae. In this study, with the goal of providing an entire compendium of the secondary structures of the various viroid species, a total of thirteen new Pospiviroidae members were probed in solution using the SHAPE protocol. More specifically, the secondary structures of eleven species for which the genus was previously known were initially elucidated. At this point, considering all of the SHAPE elucidated secondary structures, a classification system for viroids in their respective genera was proposed. On the basis of the structural classification reported here, the probings of both the Grapevine latent viroid and the Dahlia latent viroid provide sound arguments for the determination of their respective genera, which appear to be Apscaviroid and Hostuviroid, respectively. More importantly, this study provides the complete repertoire of the secondary structures, mapped in solution, of all of the accepted viroid species reported thus far. In addition, a classification scheme based on structural hallmarks, an important tool for many biological studies, is proposed.

  3. Structural Topology Optimization Based on the Smoothed Finite Element Method

    Directory of Open Access Journals (Sweden)

    Vahid Shobeiri

    Full Text Available Abstract In this paper, the smoothed finite element method, incorporated with the level set method, is employed to carry out the topology optimization of continuum structures. The structural compliance is minimized subject to a constraint on the weight of material used. The cell-based smoothed finite element method is employed to improve the accuracy and stability of the standard finite element method. Several numerical examples are presented to prove the validity and utility of the proposed method. The obtained results are compared with those obtained by several standard finite element-based examples in order to access the applicability and effectiveness of the proposed method. The common numerical instabilities of the structural topology optimization problems such as checkerboard pattern and mesh dependency are studied in the examples.

  4. Biomedical application of hierarchically built structures based on metal oxides

    Science.gov (United States)

    Korovin, M. S.; Fomenko, A. N.

    2017-12-01

    Nowadays, the use of hierarchically built structures in biology and medicine arouses much interest. The aim of this work is to review and summarize the available literature data about hierarchically organized structures in biomedical application. Nanoparticles can serve as an example of such structures. Medicine holds a special place among various application methods of similar systems. Special attention is paid to inorganic nanoparticles based on different metal oxides and hydroxides, such as iron, zinc, copper, and aluminum. Our investigations show that low-dimensional nanostructures based on aluminum oxides and hydroxides have an inhibitory effect on tumor cells and possess an antimicrobial activity. At the same time, it is obvious that the large-scale use of nanoparticles by humans needs to thoroughly study their properties. Special attention should be paid to the study of nanoparticle interaction with living biological objects. The numerous data show that there is no clear understanding of interaction mechanisms between nanoparticles and various cell types.

  5. Reliability analysis of offshore structures using OMA based fatigue stresses

    DEFF Research Database (Denmark)

    Silva Nabuco, Bruna; Aissani, Amina; Glindtvad Tarpø, Marius

    2017-01-01

    points of the structure, the stress history can be calculated in any arbitrary point of the structure. The accuracy of the estimated actual stress is analyzed by experimental tests on a scale model where the obtained stresses are compared to strain gauges measurements. After evaluating the fatigue...... affect the accuracy of the performance evaluation. It can be mentioned mainly the uncertainties related to the materials, the uncertainty on Miner’s rule and the uncertainty on the SN curve but most importantly is the uncertainty on the stress ranges induced by the wave loading. In this paper, the mainly...... focus is on the uncertainty observed on the different stresses used to predict the damage. This uncertainty can be reduced by Modal Based Fatigue Monitoring which is a technique based on continuously measuring of the accelerations in few points of the structure with the use of accelerometers known...

  6. A new entropy based method for computing software structural complexity

    CERN Document Server

    Roca, J L

    2002-01-01

    In this paper a new methodology for the evaluation of software structural complexity is described. It is based on the entropy evaluation of the random uniform response function associated with the so called software characteristic function SCF. The behavior of the SCF with the different software structures and their relationship with the number of inherent errors is investigated. It is also investigated how the entropy concept can be used to evaluate the complexity of a software structure considering the SCF as a canonical representation of the graph associated with the control flow diagram. The functions, parameters and algorithms that allow to carry out this evaluation are also introduced. After this analytic phase follows the experimental phase, verifying the consistency of the proposed metric and their boundary conditions. The conclusion is that the degree of software structural complexity can be measured as the entropy of the random uniform response function of the SCF. That entropy is in direct relation...

  7. Inelastic Structural Control Based on MBC and FAM

    Directory of Open Access Journals (Sweden)

    Li Gang

    2011-01-01

    Full Text Available A complex structure has the characters of many degrees of freedom and intricate shape, especially inelastic behavior under strong external loadings. It is hard to apply the structural control technology to it. In this paper, a new method that combines the Market-Based Control (MBC strategy and Force Analogy Method (FAM is presented to analyze the inelastic behavior of structure with magnetorheological dampers. The MBC is used to reduce the structural vibration response, and FAM is proposed to perform the inelastic analysis. A numerical example is used to compare the control effect of the new method and LQR algorithm, which show the accuracy and efficiency of the proposed computational method.

  8. A fingerprint based metric for measuring similarities of crystalline structures

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Li; Fuhrer, Tobias; Schaefer, Bastian; Grauzinyte, Migle; Goedecker, Stefan, E-mail: stefan.goedecker@unibas.ch [Department of Physics, Universität Basel, Klingelbergstr. 82, 4056 Basel (Switzerland); Amsler, Maximilian [Department of Physics, Universität Basel, Klingelbergstr. 82, 4056 Basel (Switzerland); Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Faraji, Somayeh; Rostami, Samare; Ghasemi, S. Alireza [Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Zanjan (Iran, Islamic Republic of); Sadeghi, Ali [Physics Department, Shahid Beheshti University, G. C., Evin, 19839 Tehran (Iran, Islamic Republic of); Wolverton, Chris [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

    2016-01-21

    Measuring similarities/dissimilarities between atomic structures is important for the exploration of potential energy landscapes. However, the cell vectors together with the coordinates of the atoms, which are generally used to describe periodic systems, are quantities not directly suitable as fingerprints to distinguish structures. Based on a characterization of the local environment of all atoms in a cell, we introduce crystal fingerprints that can be calculated easily and define configurational distances between crystalline structures that satisfy the mathematical properties of a metric. This distance between two configurations is a measure of their similarity/dissimilarity and it allows in particular to distinguish structures. The new method can be a useful tool within various energy landscape exploration schemes, such as minima hopping, random search, swarm intelligence algorithms, and high-throughput screenings.

  9. A fingerprint based metric for measuring similarities of crystalline structures

    Science.gov (United States)

    Zhu, Li; Amsler, Maximilian; Fuhrer, Tobias; Schaefer, Bastian; Faraji, Somayeh; Rostami, Samare; Ghasemi, S. Alireza; Sadeghi, Ali; Grauzinyte, Migle; Wolverton, Chris; Goedecker, Stefan

    2016-01-01

    Measuring similarities/dissimilarities between atomic structures is important for the exploration of potential energy landscapes. However, the cell vectors together with the coordinates of the atoms, which are generally used to describe periodic systems, are quantities not directly suitable as fingerprints to distinguish structures. Based on a characterization of the local environment of all atoms in a cell, we introduce crystal fingerprints that can be calculated easily and define configurational distances between crystalline structures that satisfy the mathematical properties of a metric. This distance between two configurations is a measure of their similarity/dissimilarity and it allows in particular to distinguish structures. The new method can be a useful tool within various energy landscape exploration schemes, such as minima hopping, random search, swarm intelligence algorithms, and high-throughput screenings.

  10. A fingerprint based metric for measuring similarities of crystalline structures

    International Nuclear Information System (INIS)

    Zhu, Li; Fuhrer, Tobias; Schaefer, Bastian; Grauzinyte, Migle; Goedecker, Stefan; Amsler, Maximilian; Faraji, Somayeh; Rostami, Samare; Ghasemi, S. Alireza; Sadeghi, Ali; Wolverton, Chris

    2016-01-01

    Measuring similarities/dissimilarities between atomic structures is important for the exploration of potential energy landscapes. However, the cell vectors together with the coordinates of the atoms, which are generally used to describe periodic systems, are quantities not directly suitable as fingerprints to distinguish structures. Based on a characterization of the local environment of all atoms in a cell, we introduce crystal fingerprints that can be calculated easily and define configurational distances between crystalline structures that satisfy the mathematical properties of a metric. This distance between two configurations is a measure of their similarity/dissimilarity and it allows in particular to distinguish structures. The new method can be a useful tool within various energy landscape exploration schemes, such as minima hopping, random search, swarm intelligence algorithms, and high-throughput screenings

  11. Modern earthquake engineering offshore and land-based structures

    CERN Document Server

    Jia, Junbo

    2017-01-01

    This book addresses applications of earthquake engineering for both offshore and land-based structures. It is self-contained as a reference work and covers a wide range of topics, including topics related to engineering seismology, geotechnical earthquake engineering, structural engineering, as well as special contents dedicated to design philosophy, determination of ground motions, shock waves, tsunamis, earthquake damage, seismic response of offshore and arctic structures, spatial varied ground motions, simplified and advanced seismic analysis methods, sudden subsidence of offshore platforms, tank liquid impacts during earthquakes, seismic resistance of non-structural elements, and various types of mitigation measures, etc. The target readership includes professionals in offshore and civil engineering, officials and regulators, as well as researchers and students in this field.

  12. Global stability-based design optimization of truss structures using ...

    Indian Academy of Sciences (India)

    Furthermore, a pure pareto-ranking based multi-objective optimization model is employed for the design optimization of the truss structure with multiple objectives. The computational performance of the optimization model is increased by implementing an island model into its evolutionary search mechanism. The proposed ...

  13. Reliability-Based Inspection Planning for Structural Systems

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    1993-01-01

    A general model for reliability-based optimal inspection and repair strategies for structural systems is described. The total expected costs in the design lifetime is minimized with the number of inspections, the inspection times and efforts as decision variables. The equivalence of this model wi...

  14. Discrete Discriminant analysis based on tree-structured graphical models

    DEFF Research Database (Denmark)

    Perez de la Cruz, Gonzalo; Eslava, Guillermina

    The purpose of this paper is to illustrate the potential use of discriminant analysis based on tree{structured graphical models for discrete variables. This is done by comparing its empirical performance using estimated error rates for real and simulated data. The results show that discriminant...

  15. Bending-active reciprocal structures based on equilateral polyhedral geometries

    DEFF Research Database (Denmark)

    Popovic Larsen, Olga; BRANCART, Stijn; DE TEMMERMAN, Niels

    2017-01-01

    the principle by developing a design methodology based on polyhedral shapes. As this work is part of a research on transformable, rapidly assembled structures, the focus lies on simplicity of the connections, uniformity of the components and reconfigurability. This paper discusses the development of a kit...

  16. Electronic structure of Fe- vs. Ru-based dye molecules

    DEFF Research Database (Denmark)

    Johnson, Phillip S.; Cook, Peter L.; Zegkinoglou, Ioannis

    2013-01-01

    In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe- and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold, octah...

  17. Internal Structure of DISCOVER: A Performance-based Assessment.

    Science.gov (United States)

    Sarouphim, Ketty M.

    2000-01-01

    A study involving 257 Navajo and Mexican-American elementary students investigated the internal structure of the DISCOVER assessment, a performance-based assessment grounded in Gardner's theory of multiple intelligence. Results showed low interrating correlations among the five assessment activities, indicating students gifted in one intelligence…

  18. Structure and properties of compositions based on petroleum sulfonic acids

    Energy Technology Data Exchange (ETDEWEB)

    Tutorskii, I.A.; Sultanova, A.S.; Belkina, E.V.; Fomin, A.G. [Lomonosov Academy of Fine Chemical Technology, Moscow (Russian Federation)

    1995-03-01

    Colloidal characteristics of compositions based on petroleum sulfonic acids were studied. Neutralized heavy oil residue exhibits surface-active properties and contains an ultradisperse filler. Analysis of the compositions by size-exclusion-chromatography shows deep structural changes in the heavy acid residue upon neutralization with calcium carbonate.

  19. An improved AODV routing protocol based on tower structure

    Directory of Open Access Journals (Sweden)

    Li Yong Qiang

    2016-01-01

    Full Text Available The paper proposed a new routing protocol(IAODV based on tower structure in the Ad Hoc network for the problem which Location Routing Protocol need hardware and Complex algorithm. By the simulation, The complexity of the new routing protocol is reduced without reducing the performance of the network.

  20. Gigascale Silicon Photonic Transmitters Integrating HBT-based Carrier-injection Electroabsorption Modulator Structures

    Science.gov (United States)

    Fu, Enjin

    injection modulators and light-emitting diodes (LED) with drive voltage requirements below 1.5V. Measurement results show an optical link based on a 70MHz red LED work well at 300Mbps by using the pre-emphasis driver module. A traveling wave electrode (TWE) modulator structure is presented, including a novel design methodology to address process limitations imposed by a commercial silicon fabrication technology. Results from 3D full wave EM simulation demonstrate the application of the design methodology to achieve specifications, including phase velocity matching, insertion loss, and impedance matching. Results show the HBT-based TWE-EAM system has the bandwidth higher than 60GHz.